1 <!doctype linuxdoc system> <!-- -*- text-mode -*- -->
4 <title>ca65 Users Guide
5 <author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
6 <url url="mailto:greg.king5@verizon.net" name="Greg King">
10 ca65 is a powerful macro assembler for the 6502, 65C02, and 65816 CPUs. It is
11 used as a companion assembler for the cc65 crosscompiler, but it may also be
12 used as a standalone product.
15 <!-- Table of contents -->
18 <!-- Begin the document -->
22 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
23 compiler, originally developed by John R. Dunning. I had some problems with
24 ra65 and the copyright does not permit some things which I wanted to be
25 possible, so I decided to write a completely new assembler/linker/archiver
26 suite for the cc65 compiler. ca65 is part of this suite.
28 Some parts of the assembler (code generation and some routines for symbol
29 table handling) are taken from an older crossassembler named a816 written
30 by me a long time ago.
33 <sect1>Design criteria<p>
35 Here's a list of the design criteria, that I considered important for the
40 <item> The assembler must support macros. Macros are not essential, but they
41 make some things easier, especially when you use the assembler in the
42 backend of a compiler.
43 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
44 thinking about a 65816 backend for the C compiler, and even my old
45 a816 assembler had support for these CPUs, so this wasn't really a
47 <item> The assembler must produce relocatable code. This is necessary for the
48 compiler support, and it is more convenient.
49 <item> Conditional assembly must be supported. This is a must for bigger
50 projects written in assembler (like Elite128).
51 <item> The assembler must support segments, and it must support more than
52 three segments (this is the count, most other assemblers support).
53 Having more than one code segments helps developing code for systems
54 with a divided ROM area (like the C64).
55 <item> The linker must be able to resolve arbitrary expressions. It should
56 be able to get things like
63 <item> True lexical nesting for symbols. This is very convenient for larger
65 <item> "Cheap" local symbols without lexical nesting for those quick, late
67 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
68 introduced the concept into the object file format use by the new cc65
70 <item> The assembler will be a one pass assembler. There was no real need for
71 this decision, but I've written several multipass assemblers, and it
72 started to get boring. A one pass assembler needs much more elaborated
73 data structures, and because of that it's much more fun:-)
74 <item> Non-GPLed code that may be used in any project without restrictions or
75 fear of "GPL infecting" other code.
83 <sect1>Command line option overview<p>
85 The assembler accepts the following options:
88 ---------------------------------------------------------------------------
89 Usage: ca65 [options] file
91 -D name[=value] Define a symbol
92 -I dir Set an include directory search path
93 -U Mark unresolved symbols as import
94 -V Print the assembler version
95 -W n Set warning level n
97 -g Add debug info to object file
99 -i Ignore case of symbols
100 -l name Create a listing file if assembly was ok
101 -mm model Set the memory model
102 -o name Name the output file
104 -t sys Set the target system
105 -v Increase verbosity
108 --auto-import Mark unresolved symbols as import
109 --bin-include-dir dir Set a search path for binary includes
110 --cpu type Set cpu type
111 --create-dep name Create a make dependency file
112 --create-full-dep name Create a full make dependency file
114 --debug-info Add debug info to object file
115 --feature name Set an emulation feature
116 --help Help (this text)
117 --ignore-case Ignore case of symbols
118 --include-dir dir Set an include directory search path
119 --large-alignment Don't warn about large alignments
120 --listing name Create a listing file if assembly was ok
121 --list-bytes n Maximum number of bytes per listing line
122 --memory-model model Set the memory model
123 --pagelength n Set the page length for the listing
124 --relax-checks Relax some checks (see docs)
125 --smart Enable smart mode
126 --target sys Set the target system
127 --verbose Increase verbosity
128 --version Print the assembler version
129 ---------------------------------------------------------------------------
133 <sect1>Command line options in detail<p>
135 Here is a description of all the command line options:
139 <label id="option--bin-include-dir">
140 <tag><tt>--bin-include-dir dir</tt></tag>
142 Name a directory which is searched for binary include files. The option
143 may be used more than once to specify more than one directory to search. The
144 current directory is always searched first before considering any
145 additional directories. See also the section about <ref id="search-paths"
146 name="search paths">.
149 <label id="option--cpu">
150 <tag><tt>--cpu type</tt></tag>
152 Set the default for the CPU type. The option takes a parameter, which
155 6502, 6502X, 65SC02, 65C02, 65816, sweet16, HuC6280, 4510
158 <label id="option-create-dep">
159 <tag><tt>--create-dep name</tt></tag>
161 Tells the assembler to generate a file containing the dependency list for
162 the assembled module in makefile syntax. The output is written to a file
163 with the given name. The output does not include files passed via debug
164 information to the assembler.
167 <label id="option-create-full-dep">
168 <tag><tt>--create-full-dep name</tt></tag>
170 Tells the assembler to generate a file containing the dependency list for
171 the assembled module in makefile syntax. The output is written to a file
172 with the given name. The output does include files passed via debug
173 information to the assembler.
176 <tag><tt>-d, --debug</tt></tag>
178 Enables debug mode, something that should not be needed for mere
182 <label id="option--feature">
183 <tag><tt>--feature name</tt></tag>
185 Enable an emulation feature. This is identical as using <tt/.FEATURE/
186 in the source with two exceptions: Feature names must be lower case, and
187 each feature must be specified by using an extra <tt/--feature/ option,
188 comma separated lists are not allowed.
190 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
191 command for a list of emulation features.
194 <label id="option-g">
195 <tag><tt>-g, --debug-info</tt></tag>
197 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
198 used, the assembler will add a section to the object file that contains
199 all symbols (including local ones) together with the symbol values and
200 source file positions. The linker will put these additional symbols into
201 the VICE label file, so even local symbols can be seen in the VICE
205 <label id="option-h">
206 <tag><tt>-h, --help</tt></tag>
208 Print the short option summary shown above.
211 <label id="option-i">
212 <tag><tt>-i, --ignore-case</tt></tag>
214 This option makes the assembler case insensitive on identifiers and labels.
215 This option will override the default, but may itself be overridden by the
216 <tt><ref id=".CASE" name=".CASE"></tt> control command.
219 <label id="option-l">
220 <tag><tt>-l name, --listing name</tt></tag>
222 Generate an assembler listing with the given name. A listing file will
223 never be generated in case of assembly errors.
226 <label id="option--large-alignment">
227 <tag><tt>--large-alignment</tt></tag>
229 Disable warnings about a large combined alignment. See the discussion of the
230 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
233 <label id="option--list-bytes">
234 <tag><tt>--list-bytes n</tt></tag>
236 Set the maximum number of bytes printed in the listing for one line of
237 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
238 for more information. The value zero can be used to encode an unlimited
239 number of printed bytes.
242 <label id="option-mm">
243 <tag><tt>-mm model, --memory-model model</tt></tag>
245 Define the default memory model. Possible model specifiers are near, far and
249 <label id="option-o">
250 <tag><tt>-o name</tt></tag>
252 The default output name is the name of the input file with the extension
253 replaced by ".o". If you don't like that, you may give another name with
254 the -o option. The output file will be placed in the same directory as
255 the source file, or, if -o is given, the full path in this name is used.
258 <label id="option--pagelength">
259 <tag><tt>--pagelength n</tt></tag>
261 sets the length of a listing page in lines. See the <tt><ref
262 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
265 <label id="option--relax-checks">
266 <tag><tt>--relax-checks</tt></tag>
268 Relax some checks done by the assembler. This will allow code that is an
269 error in most cases and flagged as such by the assembler, but can be valid
270 in special situations.
274 <item>Short branches between two different segments.
275 <item>Byte sized address loads where the address is not a zeropage address.
279 <label id="option-s">
280 <tag><tt>-s, --smart-mode</tt></tag>
282 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
283 pseudo instruction) the assembler will track usage of the <tt/REP/ and
284 <tt/SEP/ instructions in 65816 mode and update the operand sizes
285 accordingly. If the operand of such an instruction cannot be evaluated by
286 the assembler (for example, because the operand is an imported symbol), a
289 Beware: Since the assembler cannot trace the execution flow this may
290 lead to false results in some cases. If in doubt, use the .ixx and .axx
291 instructions to tell the assembler about the current settings. Smart
292 mode is off by default.
295 <label id="option-t">
296 <tag><tt>-t sys, --target sys</tt></tag>
298 Set the target system. This will enable translation of character strings and
299 character constants into the character set of the target platform. The
300 default for the target system is "none", which means that no translation
301 will take place. The assembler supports the same target systems as the
302 compiler, see there for a list.
304 Depending on the target, the default CPU type is also set. This can be
305 overriden by using the <tt/<ref id="option--cpu" name="--cpu">/ option.
308 <label id="option-v">
309 <tag><tt>-v, --verbose</tt></tag>
311 Increase the assembler verbosity. Usually only needed for debugging
312 purposes. You may use this option more than one time for even more
316 <label id="option-D">
317 <tag><tt>-D</tt></tag>
319 This option allows you to define symbols on the command line. Without a
320 value, the symbol is defined with the value zero. When giving a value,
321 you may use the '$' prefix for hexadecimal symbols. Please note
322 that for some operating systems, '$' has a special meaning, so
323 you may have to quote the expression.
326 <label id="option-I">
327 <tag><tt>-I dir, --include-dir dir</tt></tag>
329 Name a directory which is searched for include files. The option may be
330 used more than once to specify more than one directory to search. The
331 current directory is always searched first before considering any
332 additional directories. See also the section about <ref id="search-paths"
333 name="search paths">.
336 <label id="option-U">
337 <tag><tt>-U, --auto-import</tt></tag>
339 Mark symbols that are not defined in the sources as imported symbols. This
340 should be used with care since it delays error messages about typos and such
341 until the linker is run. The compiler uses the equivalent of this switch
342 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
343 symbols for the runtime library. However, the compiler is supposed to
344 generate code that runs through the assembler without problems, something
345 which is not always true for assembler programmers.
348 <label id="option-V">
349 <tag><tt>-V, --version</tt></tag>
351 Print the version number of the assembler. If you send any suggestions
352 or bugfixes, please include the version number.
355 <label id="option-W">
356 <tag><tt>-Wn</tt></tag>
358 Set the warning level for the assembler. Using -W2 the assembler will
359 even warn about such things like unused imported symbols. The default
360 warning level is 1, and it would probably be silly to set it to
368 <sect>Search paths<label id="search-paths"><p>
370 Normal include files are searched in the following places:
373 <item>The current file's directory.
374 <item>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
376 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
377 <item>A subdirectory named <tt/asminc/ of the directory defined in the
378 environment variable <tt/CC65_HOME/, if it is defined.
379 <item>An optionally compiled-in directory.
382 Binary include files are searched in the following places:
385 <item>The current file's directory.
386 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
387 name="--bin-include-dir">/ option on the command line.
392 <sect>Input format<p>
394 <sect1>Assembler syntax<p>
396 The assembler accepts the standard 6502/65816 assembler syntax. One line may
397 contain a label (which is identified by a colon), and, in addition to the
398 label, an assembler mnemonic, a macro, or a control command (see section <ref
399 id="control-commands" name="Control Commands"> for supported control
400 commands). Alternatively, the line may contain a symbol definition using
401 the '=' token. Everything after a semicolon is handled as a comment (that is,
404 Here are some examples for valid input lines:
407 Label: ; A label and a comment
408 lda #$20 ; A 6502 instruction plus comment
409 L1: ldx #$20 ; Same with label
410 L2: .byte "Hello world" ; Label plus control command
411 mymac $20 ; Macro expansion
412 MySym = 3*L1 ; Symbol definition
413 MaSym = Label ; Another symbol
416 The assembler accepts
419 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
420 <tt><ref id=".P02" name=".P02"></tt> command was given).
421 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
422 <ref id="6502X-mode" name="6502X mode">.
423 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
424 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
425 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
426 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
427 <item>all valid 65816 mnemonics when in 65816 mode (after the
428 <tt><ref id=".P816" name=".P816"></tt> command was given).
429 <item>all valid 4510 mnemonics when in 4510 mode (after the
430 <tt><ref id=".P4510" name=".P4510"></tt> command was given).
436 In 65816 mode, several aliases are accepted, in addition to the official
440 <item><tt>CPA</tt> is an alias for <tt>CMP</tt>
441 <item><tt>DEA</tt> is an alias for <tt>DEC A</tt>
442 <item><tt>INA</tt> is an alias for <tt>INC A</tt>
443 <item><tt>SWA</tt> is an alias for <tt>XBA</tt>
444 <item><tt>TAD</tt> is an alias for <tt>TCD</tt>
445 <item><tt>TAS</tt> is an alias for <tt>TCS</tt>
446 <item><tt>TDA</tt> is an alias for <tt>TDC</tt>
447 <item><tt>TSA</tt> is an alias for <tt>TSC</tt>
451 <sect1>6502X mode<label id="6502X-mode"><p>
453 6502X mode is an extension to the normal 6502 mode. In this mode, several
454 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
455 these instructions are illegal, there are no official mnemonics for them. The
456 unofficial ones are taken from <url
457 url="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
458 ones marked as "stable" are supported. The following table uses information
459 from the mentioned web page, for more information, see there.
462 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
463 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
464 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
465 <item><tt>AXS: X:=A and X-#{imm};</tt>
466 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
467 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
468 <item><tt>LAS: A,X,S:={adr} and S;</tt>
469 <item><tt>LAX: A,X:={adr};</tt>
470 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
471 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
472 <item><tt>SAX: {adr}:=A and X;</tt>
473 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
474 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
480 The 4510 is a microcontroller that is the core of the Commodore C65 aka C64DX.
481 It contains among other functions a slightly modified 65CE02/4502 CPU, to allow
482 address mapping for 20 bits of address space (1 megabyte addressable area).
483 As compared to the description of the CPU in the
484 <url url="http://www.zimmers.net/anonftp/pub/cbm/c65/c65manualupdated.txt.gz"
485 name="C65 System Specification">
486 <url url="https://raw.githubusercontent.com/MEGA65/c65-specifications/master/c65manualupdated.txt"
487 name="(updated version)"> uses these changes:
489 <item><tt>LDA (d,SP),Y</tt> may also be written as <tt>LDA (d,S),Y</tt>
490 (matching the 65816 notataion).
491 <item>All branch instruction allow now 16 bit offsets. To use a 16 bit
492 branch you have to prefix these with an "L" (e.g. "<tt>LBNE</tt>" instead of
493 "<tt>BNE</tt>"). This might change at a later implementation of the assembler.
495 For more information about the Commodore C65/C64DX and the 4510 CPU, see
496 <url url="http://www.zimmers.net/anonftp/pub/cbm/c65/"> and
497 <url url="https://en.wikipedia.org/wiki/Commodore_65" name="Wikipedia">.
500 <sect1>sweet16 mode<label id="sweet16-mode"><p>
502 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
503 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
504 generate code for this pseudo CPU when switched into sweet16 mode. The
505 following is special in sweet16 mode:
509 <item>The '@' character denotes indirect addressing and is no longer available
510 for cheap local labels. If you need cheap local labels, you will have to
511 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
512 name=".LOCALCHAR">/ command.
514 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
515 these identifiers are reserved words.
519 Please note that the assembler does neither supply the interpreter needed for
520 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
521 nor does it call the interpreter. All this must be done by your program. Apple
522 ][ programmers do probably know how to use sweet16 mode.
524 For more information about SWEET 16, see
525 <url url="http://www.6502.org/source/interpreters/sweet16.htm">.
528 <sect1>Number format<p>
530 For literal values, the assembler accepts the widely used number formats: A
531 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
532 denotes a binary value, and a bare number is interpreted as a decimal. There
533 are currently no octal values and no floats.
536 <sect1>Conditional assembly<p>
538 Please note that when using the conditional directives (<tt/.IF/ and friends),
539 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
540 that are not assembled. The reason for this behaviour is that the assembler
541 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
542 conversion of the input stream into tokens still takes place. As a consequence
543 conditional assembly directives may <bf/not/ be used to prevent normal text
544 (used as a comment or similar) from being assembled. <p>
550 <sect1>Expression evaluation<p>
552 All expressions are evaluated with (at least) 32 bit precision. An
553 expression may contain constant values and any combination of internal and
554 external symbols. Expressions that cannot be evaluated at assembly time
555 are stored inside the object file for evaluation by the linker.
556 Expressions referencing imported symbols must always be evaluated by the
560 <sect1>Size of an expression result<p>
562 Sometimes, the assembler must know about the size of the value that is the
563 result of an expression. This is usually the case, if a decision has to be
564 made, to generate a zero page or an absolute memory references. In this
565 case, the assembler has to make some assumptions about the result of an
569 <item> If the result of an expression is constant, the actual value is
570 checked to see if it's a byte sized expression or not.
571 <item> If the expression is explicitly casted to a byte sized expression by
572 one of the '>', '<' or '^' operators, it is a byte expression.
573 <item> If this is not the case, and the expression contains a symbol,
574 explicitly declared as zero page symbol (by one of the .importzp or
575 .exportzp instructions), then the whole expression is assumed to be
577 <item> If the expression contains symbols that are not defined, and these
578 symbols are local symbols, the enclosing scopes are searched for a
579 symbol with the same name. If one exists and this symbol is defined,
580 its attributes are used to determine the result size.
581 <item> In all other cases the expression is assumed to be word sized.
584 Note: If the assembler is not able to evaluate the expression at assembly
585 time, the linker will evaluate it and check for range errors as soon as
589 <sect1>Boolean expressions<p>
591 In the context of a boolean expression, any non zero value is evaluated as
592 true, any other value to false. The result of a boolean expression is 1 if
593 it's true, and zero if it's false. There are boolean operators with extreme
594 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
595 operators are shortcut operators. That is, if the result of the expression is
596 already known, after evaluating the left hand side, the right hand side is
600 <sect1>Constant expressions<p>
602 Sometimes an expression must evaluate to a constant without looking at any
603 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
604 that decides if parts of the code are assembled or not. An expression used in
605 the <tt/.IF/ command cannot reference a symbol defined later, because the
606 decision about the <tt/.IF/ must be made at the point when it is read. If the
607 expression used in such a context contains only constant numerical values,
608 there is no problem. When unresolvable symbols are involved it may get harder
609 for the assembler to determine if the expression is actually constant, and it
610 is even possible to create expressions that aren't recognized as constant.
611 Simplifying the expressions will often help.
613 In cases where the result of the expression is not needed immediately, the
614 assembler will delay evaluation until all input is read, at which point all
615 symbols are known. So using arbitrary complex constant expressions is no
616 problem in most cases.
620 <sect1>Available operators<label id="operators"><p>
624 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
625 | Built-in string functions| 0@
627 | Built-in pseudo-variables| 1@
628 | Built-in pseudo-functions| 1@
629 +| Unary positive| 1@
630 -| Unary negative| 1@
632 .BITNOT| Unary bitwise not| 1@
634 .LOBYTE| Unary low-byte operator| 1@
636 .HIBYTE| Unary high-byte operator| 1@
638 .BANKBYTE| Unary bank-byte operator| 1@
640 *| Multiplication| 2@
642 .MOD| Modulo operator| 2@
644 .BITAND| Bitwise and| 2@
646 .BITXOR| Binary bitwise xor| 2@
648 .SHL| Shift-left operator| 2@
650 .SHR| Shift-right operator| 2@
652 +| Binary addition| 3@
653 -| Binary subtraction| 3@
655 .BITOR| Bitwise or| 3@
657 = | Compare operator (equal)| 4@
658 <>| Compare operator (not equal)| 4@
659 <| Compare operator (less)| 4@
660 >| Compare operator (greater)| 4@
661 <=| Compare operator (less or equal)| 4@
662 >=| Compare operator (greater or equal)| 4@
665 .AND| Boolean and| 5@
666 .XOR| Boolean xor| 5@
668 ||<newline>
672 .NOT| Boolean not| 7@<hline>
674 <caption>Available operators, sorted by precedence
677 To force a specific order of evaluation, parentheses may be used, as usual.
681 <sect>Symbols and labels<p>
683 A symbol or label is an identifier that starts with a letter and is followed
684 by letters and digits. Depending on some features enabled (see
685 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
686 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
687 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
688 other characters may be present. Use of identifiers consisting of a single
689 character will not work in all cases, because some of these identifiers are
690 reserved keywords (for example "A" is not a valid identifier for a label,
691 because it is the keyword for the accumulator).
693 The assembler allows you to use symbols instead of naked values to make
694 the source more readable. There are a lot of different ways to define and
695 use symbols and labels, giving a lot of flexibility.
697 <sect1>Numeric constants<p>
699 Numeric constants are defined using the equal sign or the label assignment
700 operator. After doing
706 may use the symbol "two" in every place where a number is expected, and it is
707 evaluated to the value 2 in this context. The label assignment operator is
708 almost identical, but causes the symbol to be marked as a label, so it may be
709 handled differently in a debugger:
715 The right side can of course be an expression:
722 <label id="variables">
723 <sect1>Numeric variables<p>
725 Within macros and other control structures (<tt><ref id=".REPEAT"
726 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
727 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
728 symbol that may get assigned a different value later:
732 lda #four ; Loads 4 into A
734 lda #four ; Loads 3 into A
737 Since the value of the symbol can change later, it must be possible to
738 evaluate it when used (no delayed evaluation as with normal symbols). So the
739 expression used as the value must be constant.
741 Following is an example for a macro that generates a different label each time
742 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
743 and a numeric variable named <tt>lcount</tt>.
746 .lcount .set 0 ; Initialize the counter
749 .ident (.sprintf ("L%04X", lcount)):
750 lcount .set lcount + 1
755 <sect1>Standard labels<p>
757 A label is defined by writing the name of the label at the start of the line
758 (before any instruction mnemonic, macro or pseudo directive), followed by a
759 colon. This will declare a symbol with the given name and the value of the
760 current program counter.
763 <sect1>Local labels and symbols<p>
765 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
766 create regions of code where the names of labels and symbols are local to this
767 region. They are not known outside of this region and cannot be accessed from
768 there. Such regions may be nested like PROCEDUREs in Pascal.
770 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
771 directive for more information.
774 <sect1>Cheap local labels<p>
776 Cheap local labels are defined like standard labels, but the name of the
777 label must begin with a special symbol (usually '@', but this can be
778 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
781 Cheap local labels are visible only between two non cheap labels. As soon as a
782 standard symbol is encountered (this may also be a local symbol if inside a
783 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
784 cheap local symbol goes out of scope.
786 You may use cheap local labels as an easy way to reuse common label
787 names like "Loop". Here is an example:
790 Clear: lda #$00 ; Global label
792 @Loop: sta Mem,y ; Local label
796 Sub: ... ; New global label
797 bne @Loop ; ERROR: Unknown identifier!
800 <sect1>Unnamed labels<p>
802 If you really want to write messy code, there are also unnamed labels. These
803 labels do not have a name (you guessed that already, didn't you?). A colon is
804 used to mark the absence of the name.
806 Unnamed labels may be accessed by using the colon plus several minus or plus
807 characters as a label designator. Using the '-' characters will create a back
808 reference (use the n'th label backwards), using '+' will create a forward
809 reference (use the n'th label in forward direction). An example will help to
832 As you can see from the example, unnamed labels will make even short
833 sections of code hard to understand, because you have to count labels
834 to find branch targets (this is the reason why I for my part do
835 prefer the "cheap" local labels). Nevertheless, unnamed labels are
836 convenient in some situations, so it's your decision.
838 <em/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
839 unnamed ones, so scopes don't have an effect on unnamed labels.
843 <sect1>Using macros to define labels and constants<p>
845 While there are drawbacks with this approach, it may be handy in a few rare
846 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
847 to define symbols or constants that may be used elsewhere. One of the
848 advantages is that you can use it to define string constants (this is not
849 possible with the other symbol types).
851 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
852 so the names do not adhere to scoping, diagnostics may be misleading, there
853 are no symbols to look up in the map file, and there is no debug info.
854 Especially the first problem in the list can lead to very nasty programming
855 errors. Because of these problems, the general advice is, <bf/NOT/ do use
856 <tt/.DEFINE/ if you don't have to.
862 .DEFINE version "SOS V2.3"
864 four = two * two ; Ok
867 .PROC ; Start local scope
868 two = 3 ; Will give "2 = 3" - invalid!
873 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
875 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
876 id="option-g" name="-g"> is given on the command line), global, local and
877 cheap local labels are written to the object file and will be available in the
878 symbol file via the linker. Unnamed labels are not written to the object file,
879 because they don't have a name which would allow to access them.
883 <sect>Scopes<label id="scopes"><p>
885 ca65 implements several sorts of scopes for symbols.
887 <sect1>Global scope<p>
889 All (non cheap local) symbols that are declared outside of any nested scopes
893 <sect1>Cheap locals<p>
895 A special scope is the scope for cheap local symbols. It lasts from one non
896 local symbol to the next one, without any provisions made by the programmer.
897 All other scopes differ in usage but use the same concept internally.
900 <sect1>Generic nested scopes<p>
902 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
903 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
904 The scope can have a name, in which case it is accessible from the outside by
905 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
906 have a name, all symbols created within the scope are local to the scope, and
907 aren't accessible from the outside.
909 A nested scope can access symbols from the local or from enclosing scopes by
910 name without using explicit scope names. In some cases there may be
911 ambiguities, for example if there is a reference to a local symbol that is not
912 yet defined, but a symbol with the same name exists in outer scopes:
924 In the example above, the <tt/lda/ instruction will load the value 3 into the
925 accumulator, because <tt/foo/ is redefined in the scope. However:
937 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
938 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
939 absolute mode is used instead. In fact, the assembler will not use absolute
940 mode by default, but it will search through the enclosing scopes for a symbol
941 with the given name. If one is found, the address size of this symbol is used.
942 This may lead to errors:
954 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
955 instruction, it will search for an already defined symbol <tt/foo/. It will
956 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
957 zeropage symbol. So the assembler will use zeropage addressing mode. If
958 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
959 the address in the <tt/lda/ instruction already translated, but since the new
960 value needs absolute addressing mode, this fails, and an error message "Range
963 Of course the most simple solution for the problem is to move the definition
964 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
965 rare cases when this cannot be done. In these cases, you can use one of the
966 address size override operators:
978 This will cause the <tt/lda/ instruction to be translated using absolute
979 addressing mode, which means changing the symbol reference later does not
983 <sect1>Nested procedures<p>
985 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
986 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
987 name, and a it will introduce a symbol with this name in the enclosing scope.
996 is actually the same as
1005 This is the reason why a procedure must have a name. If you want a scope
1006 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
1008 <em/Note:/ As you can see from the example above, scopes and symbols live in
1009 different namespaces. There can be a symbol named <tt/foo/ and a scope named
1010 <tt/foo/ without any conflicts (but see the section titled <ref
1011 id="scopesearch" name=""Scope search order"">).
1014 <sect1>Structs, unions and enums<p>
1016 Structs, unions and enums are explained in a <ref id="structs" name="separate
1017 section">, I do only cover them here, because if they are declared with a
1018 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
1019 name=".SCOPE">/. However, when no name is specified, the behaviour is
1020 different: In this case, no new scope will be opened, symbols declared within
1021 a struct, union, or enum declaration will then be added to the enclosing scope
1025 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1027 Accessing symbols from other scopes is possible by using an explicit scope
1028 specification, provided that the scope where the symbol lives in has a name.
1029 The namespace token (<tt/::/) is used to access other scopes:
1037 lda foo::bar ; Access foo in scope bar
1040 The only way to deny access to a scope from the outside is to declare a scope
1041 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1043 A special syntax is used to specify the global scope: If a symbol or scope is
1044 preceded by the namespace token, the global scope is searched:
1051 lda #::bar ; Access the global bar (which is 3)
1056 <sect1>Scope search order<label id="scopesearch"><p>
1058 The assembler searches for a scope in a similar way as for a symbol. First, it
1059 looks in the current scope, and then it walks up the enclosing scopes until
1062 However, one important thing to note when using explicit scope syntax is, that
1063 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1064 used without a preceding definition. This means that in the following
1073 lda #foo::bar ; Will load 3, not 2!
1080 the reference to the scope <tt/foo/ will use the global scope, and not the
1081 local one, because the local one is not visible at the point where it is
1084 Things get more complex if a complete chain of scopes is specified:
1095 lda #outer::inner::bar ; 1
1107 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1108 assembler will first search in the local scope for a scope named <tt/outer/.
1109 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1110 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1111 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1112 this scope, the assembler looks for a symbol named <tt/bar/.
1114 Please note that once the anchor scope is found, all following scopes
1115 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1116 assembler will search the scope tree only for the first scope (if it is not
1117 anchored in the root scope). Starting from there on, there is no flexibility,
1118 so if the scope named <tt/outer/ found by the assembler does not contain a
1119 scope named <tt/inner/, this would be an error, even if such a pair does exist
1120 (one level up in global scope).
1122 Ambiguities that may be introduced by this search algorithm may be removed by
1123 anchoring the scope specification in the global scope. In the example above,
1124 if you want to access the "other" symbol <tt/bar/, you would have to write:
1135 lda #::outer::inner::bar ; 2
1148 <sect>Address sizes and memory models<label id="address-sizes"><p>
1150 <sect1>Address sizes<p>
1152 ca65 assigns each segment and each symbol an address size. This is true, even
1153 if the symbol is not used as an address. You may also think of a value range
1154 of the symbol instead of an address size.
1156 Possible address sizes are:
1159 <item>Zeropage or direct (8 bits)
1160 <item>Absolute (16 bits)
1162 <item>Long (32 bits)
1165 Since the assembler uses default address sizes for the segments and symbols,
1166 it is usually not necessary to override the default behaviour. In cases, where
1167 it is necessary, the following keywords may be used to specify address sizes:
1170 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1171 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1172 <item>FAR for far addressing (24 bits).
1173 <item>LONG or DWORD for long addressing (32 bits).
1177 <sect1>Address sizes of segments<p>
1179 The assembler assigns an address size to each segment. Since the
1180 representation of a label within this segment is "segment start + offset",
1181 labels will inherit the address size of the segment they are declared in.
1183 The address size of a segment may be changed, by using an optional address
1184 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1185 an explanation on how this is done.
1188 <sect1>Address sizes of symbols<p>
1193 <sect1>Memory models<p>
1195 The default address size of a segment depends on the memory model used. Since
1196 labels inherit the address size from the segment they are declared in,
1197 changing the memory model is an easy way to change the address size of many
1203 <sect>Pseudo variables<label id="pseudo-variables"><p>
1205 Pseudo variables are readable in all cases, and in some special cases also
1208 <sect1><tt>*</tt><p>
1210 Reading this pseudo variable will return the program counter at the start
1211 of the current input line.
1213 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1214 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1215 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1218 <sect1><tt>.ASIZE</tt><label id=".ASIZE"><p>
1220 Reading this pseudo variable will return the current size of the
1221 Accumulator in bits.
1223 For the 65816 instruction set .ASIZE will return either 8 or 16, depending
1224 on the current size of the operand in immediate accu addressing mode.
1226 For all other CPU instruction sets, .ASIZE will always return 8.
1231 ; Reverse Subtract with Accumulator
1244 See also: <tt><ref id=".ISIZE" name=".ISIZE"></tt>
1247 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1249 Reading this pseudo variable will give a constant integer value that
1250 tells which CPU is currently enabled. It can also tell which instruction
1251 set the CPU is able to translate. The value read from the pseudo variable
1252 should be further examined by using one of the constants defined by the
1253 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1255 It may be used to replace the .IFPxx pseudo instructions or to construct
1256 even more complex expressions.
1262 .if (.cpu .bitand CPU_ISET_65816)
1274 <sect1><tt>.ISIZE</tt><label id=".ISIZE"><p>
1276 Reading this pseudo variable will return the current size of the Index
1279 For the 65816 instruction set .ISIZE will return either 8 or 16, depending
1280 on the current size of the operand in immediate index addressing mode.
1282 For all other CPU instruction sets, .ISIZE will always return 8.
1284 See also: <tt><ref id=".ASIZE" name=".ASIZE"></tt>
1287 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1289 This builtin pseudo variable is only available in macros. It is replaced by
1290 the actual number of parameters that were given in the macro invocation.
1295 .macro foo arg1, arg2, arg3
1296 .if .paramcount <> 3
1297 .error "Too few parameters for macro foo"
1303 See section <ref id="macros" name="Macros">.
1306 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1308 Reading this pseudo variable will give a constant integer value that
1309 represents the current time in POSIX standard (as seconds since the
1312 It may be used to encode the time of translation somewhere in the created
1318 .dword .time ; Place time here
1322 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1324 Reading this pseudo variable will give the assembler version according to
1325 the following formula:
1327 VER_MAJOR*$100 + VER_MINOR*$10
1329 It may be used to encode the assembler version or check the assembler for
1330 special features not available with older versions.
1334 Version 2.14 of the assembler will return $2E0 as numerical constant when
1335 reading the pseudo variable <tt/.VERSION/.
1339 <sect>Pseudo functions<label id="pseudo-functions"><p>
1341 Pseudo functions expect their arguments in parenthesis, and they have a result,
1342 either a string or an expression.
1345 <sect1><tt>.ADDRSIZE</tt><label id=".ADDRSIZE"><p>
1347 The <tt/.ADDRSIZE/ function is used to return the interal address size
1348 associated with a symbol. This can be helpful in macros when knowing the address
1349 size of symbol can help with custom instructions.
1355 .if .ADDRSIZE(foo) = 1
1356 ;do custom command based on zeropage addressing:
1358 .elseif .ADDRSIZE(foo) = 2
1359 ;do custom command based on absolute addressing:
1362 .elseif .ADDRSIZE(foo) = 0
1363 ; no address size defined for this symbol:
1364 .out .sprintf("Error, address size unknown for symbol %s", .string(foo))
1369 This command is new and must be enabled with the <tt/.FEATURE addrsize/ command.
1371 See: <tt><ref id=".FEATURE" name=".FEATURE"></tt>
1374 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1376 The <tt/.BANK/ function is used to support systems with banked memory. The
1377 argument is an expression with exactly one segment reference - usually a
1378 label. The function result is the value of the <tt/bank/ attribute assigned
1379 to the run memory area of the segment. Please see the linker documentation
1380 for more information about memory areas and their attributes.
1382 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1383 containing specific data is available.
1385 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1386 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1387 name=".LOBYTE"></tt> or similar functions to address just part of it.
1389 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1390 an expression containing <tt/.BANK/ can never be used where a constant known
1391 result is expected (for example with <tt/.RES/).
1408 .byte <.BANK (banked_func_1)
1411 .byte <.BANK (banked_func_2)
1417 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1419 The function returns the bank byte (that is, bits 16-23) of its argument.
1420 It works identical to the '^' operator.
1422 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1423 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1426 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1428 Builtin function. The function evaluates its argument in braces and yields
1429 "false" if the argument is non blank (there is an argument), and "true" if
1430 there is no argument. The token list that makes up the function argument
1431 may optionally be enclosed in curly braces. This allows the inclusion of
1432 tokens that would otherwise terminate the list (the closing right
1433 parenthesis). The curly braces are not considered part of the list, a list
1434 just consisting of curly braces is considered to be empty.
1436 As an example, the <tt/.IFBLANK/ statement may be replaced by
1444 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1446 Builtin string function. The function allows to concatenate a list of string
1447 constants separated by commas. The result is a string constant that is the
1448 concatenation of all arguments. This function is most useful in macros and
1449 when used together with the <tt/.STRING/ builtin function. The function may
1450 be used in any case where a string constant is expected.
1455 .include .concat ("myheader", ".", "inc")
1458 This is the same as the command
1461 .include "myheader.inc"
1465 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1467 Builtin function. The function evaluates its argument in braces and
1468 yields "true" if the argument is a constant expression (that is, an
1469 expression that yields a constant value at assembly time) and "false"
1470 otherwise. As an example, the .IFCONST statement may be replaced by
1477 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1479 The function returns the high byte (that is, bits 8-15) of its argument.
1480 It works identical to the '>' operator.
1482 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1483 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1486 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1488 The function returns the high word (that is, bits 16-31) of its argument.
1490 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1493 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1495 The function expects a string as its argument, and converts this argument
1496 into an identifier. If the string starts with the current <tt/<ref
1497 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1498 identifier, otherwise it will be converted into a normal identifier.
1503 .macro makelabel arg1, arg2
1504 .ident (.concat (arg1, arg2)):
1507 makelabel "foo", "bar"
1509 .word foobar ; Valid label
1513 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1515 Builtin function. Extracts the left part of a given token list.
1520 .LEFT (<int expr>, <token list>)
1523 The first integer expression gives the number of tokens to extract from
1524 the token list. The second argument is the token list itself. The token
1525 list may optionally be enclosed into curly braces. This allows the
1526 inclusion of tokens that would otherwise terminate the list (the closing
1527 right paren in the given case).
1531 To check in a macro if the given argument has a '#' as first token
1532 (immediate addressing mode), use something like this:
1537 .if (.match (.left (1, {arg}), #))
1539 ; ldax called with immediate operand
1547 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1548 name=".RIGHT"></tt> builtin functions.
1551 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1553 The function returns the low byte (that is, bits 0-7) of its argument.
1554 It works identical to the '<' operator.
1556 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1557 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1560 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1562 The function returns the low word (that is, bits 0-15) of its argument.
1564 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1567 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1569 Builtin function. Matches two token lists against each other. This is
1570 most useful within macros, since macros are not stored as strings, but
1576 .MATCH(<token list #1>, <token list #2>)
1579 Both token list may contain arbitrary tokens with the exception of the
1580 terminator token (comma resp. right parenthesis) and
1587 The token lists may optionally be enclosed into curly braces. This allows
1588 the inclusion of tokens that would otherwise terminate the list (the closing
1589 right paren in the given case). Often a macro parameter is used for any of
1592 Please note that the function does only compare tokens, not token
1593 attributes. So any number is equal to any other number, regardless of the
1594 actual value. The same is true for strings. If you need to compare tokens
1595 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1596 name=".XMATCH"></tt> function.
1600 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1601 while honoring the sign bit. The builtin processor instructions will allow
1602 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1603 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1604 to check for this and print and error for invalid calls.
1609 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1610 .error "Syntax error"
1613 cmp #$80 ; Bit 7 into carry
1614 lsr a ; Shift carry into bit 7
1619 The macro will only accept no arguments, or one argument that must be the
1620 reserved keyword "A".
1622 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1625 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1627 Builtin function. The result is the larger of two values.
1632 .MAX (<value #1>, <value #2>)
1638 ; Reserve space for the larger of two data blocks
1639 savearea: .res .max (.sizeof (foo), .sizeof (bar))
1642 See: <tt><ref id=".MIN" name=".MIN"></tt>
1645 <sect1><tt>.MID</tt><label id=".MID"><p>
1647 Builtin function. Takes a starting index, a count and a token list as
1648 arguments. Will return part of the token list.
1653 .MID (<int expr>, <int expr>, <token list>)
1656 The first integer expression gives the starting token in the list (the first
1657 token has index 0). The second integer expression gives the number of tokens
1658 to extract from the token list. The third argument is the token list itself.
1659 The token list may optionally be enclosed into curly braces. This allows the
1660 inclusion of tokens that would otherwise terminate the list (the closing
1661 right paren in the given case).
1665 To check in a macro if the given argument has a '<tt/#/' as first token
1666 (immediate addressing mode), use something like this:
1671 .if (.match (.mid (0, 1, {arg}), #))
1673 ; ldax called with immediate operand
1681 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1682 name=".RIGHT"></tt> builtin functions.
1685 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1687 Builtin function. The result is the smaller of two values.
1692 .MIN (<value #1>, <value #2>)
1698 ; Reserve space for some data, but 256 bytes maximum
1699 savearea: .res .min (.sizeof (foo), 256)
1702 See: <tt><ref id=".MAX" name=".MAX"></tt>
1705 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1707 Builtin function. The function expects an identifier as argument in braces.
1708 The argument is evaluated, and the function yields "true" if the identifier
1709 is a symbol that has already been referenced somewhere in the source file up
1710 to the current position. Otherwise the function yields false. As an example,
1711 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1717 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1720 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1722 Builtin function. Extracts the right part of a given token list.
1727 .RIGHT (<int expr>, <token list>)
1730 The first integer expression gives the number of tokens to extract from the
1731 token list. The second argument is the token list itself. The token list
1732 may optionally be enclosed into curly braces. This allows the inclusion of
1733 tokens that would otherwise terminate the list (the closing right paren in
1736 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1737 name=".MID"></tt> builtin functions.
1740 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1742 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1743 argument can be a struct/union, a struct member, a procedure, or a label. In
1744 case of a procedure or label, its size is defined by the amount of data
1745 placed in the segment where the label is relative to. If a line of code
1746 switches segments (for example in a macro) data placed in other segments
1747 does not count for the size.
1749 Please note that a symbol or scope must exist, before it is used together with
1750 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1751 A scope has preference over a symbol with the same name, so if the last part
1752 of a name represents both, a scope and a symbol, the scope is chosen over the
1755 After the following code:
1758 .struct Point ; Struct size = 4
1763 P: .tag Point ; Declare a point
1764 @P: .tag Point ; Declare another point
1776 .data ; Segment switch!!!
1782 <tag><tt/.sizeof(Point)/</tag>
1783 will have the value 4, because this is the size of struct <tt/Point/.
1785 <tag><tt/.sizeof(Point::xcoord)/</tag>
1786 will have the value 2, because this is the size of the member <tt/xcoord/
1787 in struct <tt/Point/.
1789 <tag><tt/.sizeof(P)/</tag>
1790 will have the value 4, this is the size of the data declared on the same
1791 source line as the label <tt/P/, which is in the same segment that <tt/P/
1794 <tag><tt/.sizeof(@P)/</tag>
1795 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1796 does also work for cheap local symbols.
1798 <tag><tt/.sizeof(Code)/</tag>
1799 will have the value 3, since this is amount of data emitted into the code
1800 segment, the segment that was active when <tt/Code/ was entered. Note that
1801 this value includes the amount of data emitted in child scopes (in this
1802 case <tt/Code::Inner/).
1804 <tag><tt/.sizeof(Code::Inner)/</tag>
1805 will have the value 1 as expected.
1807 <tag><tt/.sizeof(Data)/</tag>
1808 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1809 the segment is switched after entry, this data is emitted into another
1814 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1816 Builtin function. The function accepts a string and an index as
1817 arguments and returns the value of the character at the given position
1818 as an integer value. The index is zero based.
1824 ; Check if the argument string starts with '#'
1825 .if (.strat (Arg, 0) = '#')
1832 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1834 Builtin function. It expects a format string as first argument. The number
1835 and type of the following arguments depend on the format string. The format
1836 string is similar to the one of the C <tt/printf/ function. Missing things
1837 are: Length modifiers, variable width.
1839 The result of the function is a string.
1846 ; Generate an identifier:
1847 .ident (.sprintf ("%s%03d", "label", num)):
1851 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1853 Builtin function. The function accepts an argument in braces and converts
1854 this argument into a string constant. The argument may be an identifier, or
1855 a constant numeric value.
1857 Since you can use a string in the first place, the use of the function may
1858 not be obvious. However, it is useful in macros, or more complex setups.
1863 ; Emulate other assemblers:
1865 .segment .string(name)
1870 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1872 Builtin function. The function accepts a string argument in braces and
1873 evaluates to the length of the string.
1877 The following macro encodes a string as a pascal style string with
1878 a leading length byte.
1882 .byte .strlen(Arg), Arg
1887 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1889 Builtin function. The function accepts a token list in braces. The function
1890 result is the number of tokens given as argument. The token list may
1891 optionally be enclosed into curly braces which are not considered part of
1892 the list and not counted. Enclosement in curly braces allows the inclusion
1893 of tokens that would otherwise terminate the list (the closing right paren
1898 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1899 with the normal 6502 instructions). To translate it into two separate 8 bit
1900 load instructions, the '#' token has to get stripped from the argument:
1904 .if (.match (.mid (0, 1, {arg}), #))
1905 ; ldax called with immediate operand
1906 lda #<(.right (.tcount ({arg})-1, {arg}))
1907 ldx #>(.right (.tcount ({arg})-1, {arg}))
1915 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1917 Builtin function. Matches two token lists against each other. This is
1918 most useful within macros, since macros are not stored as strings, but
1924 .XMATCH(<token list #1>, <token list #2>)
1927 Both token list may contain arbitrary tokens with the exception of the
1928 terminator token (comma resp. right parenthesis) and
1935 The token lists may optionally be enclosed into curly braces. This allows
1936 the inclusion of tokens that would otherwise terminate the list (the closing
1937 right paren in the given case). Often a macro parameter is used for any of
1940 The function compares tokens <em/and/ token values. If you need a function
1941 that just compares the type of tokens, have a look at the <tt><ref
1942 id=".MATCH" name=".MATCH"></tt> function.
1944 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1948 <sect>Control commands<label id="control-commands"><p>
1950 Here's a list of all control commands and a description, what they do:
1953 <sect1><tt>.A16</tt><label id=".A16"><p>
1955 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1957 Note: This command will not emit any code, it will tell the assembler to
1958 create 16 bit operands for immediate accumulator addressing mode.
1960 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1963 <sect1><tt>.A8</tt><label id=".A8"><p>
1965 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1967 Note: This command will not emit any code, it will tell the assembler to
1968 create 8 bit operands for immediate accu addressing mode.
1970 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1973 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1975 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1976 may be used for better readability if the data words are address values. In
1977 65816 mode, the address is forced to be 16 bit wide to fit into the current
1978 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1979 must be followed by a sequence of (not necessarily constant) expressions.
1984 .addr $0D00, $AF13, _Clear
1987 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1991 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1993 Align data to a given boundary. The command expects a constant integer
1994 argument in the range 1 ... 65536, plus an optional second argument
1995 in byte range. If there is a second argument, it is used as fill value,
1996 otherwise the value defined in the linker configuration file is used
1997 (the default for this value is zero).
1999 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
2000 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
2001 number of bytes, since that would break address calculations within the
2002 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
2003 of the alignment, because that allows the number of fill bytes to be
2004 calculated in advance by the assembler. You are therefore required to
2005 specify a matching alignment for the segment in the linker config. The
2006 linker will output a warning if the alignment of the segment is less than
2007 what is necessary to have a correct alignment in the object file.
2015 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
2016 commands with different arguments. To allow the assembler to calculate the
2017 number of fill bytes in advance, the alignment of the segment must be a
2018 multiple of each of the alignment factors. This may result in unexpectedly
2019 large alignments for the segment within the module.
2030 For the assembler to be able to align correctly, the segment must be aligned
2031 to the least common multiple of 15 and 18 which is 90. The assembler will
2032 calculate this automatically and will mark the segment with this value.
2034 Unfortunately, the combined alignment may get rather large without the user
2035 knowing about it, wasting space in the final executable. If we add another
2036 alignment to the example above
2047 the assembler will force a segment alignment to the least common multiple of
2048 15, 18 and 251 - which is 22590. To protect the user against errors, the
2049 assembler will issue a warning when the combined alignment exceeds 256. The
2050 command line option <tt><ref id="option--large-alignment"
2051 name="--large-alignment"></tt> will disable this warning.
2053 Please note that with alignments that are a power of two (which were the
2054 only alignments possible in older versions of the assembler), the problem is
2055 less severe, because the least common multiple of powers to the same base is
2056 always the larger one.
2060 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
2062 Define a string with a trailing zero.
2067 Msg: .asciiz "Hello world"
2070 This will put the string "Hello world" followed by a binary zero into
2071 the current segment. There may be more strings separated by commas, but
2072 the binary zero is only appended once (after the last one).
2075 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2077 Add an assertion. The command is followed by an expression, an action
2078 specifier, and an optional message that is output in case the assertion
2079 fails. If no message was given, the string "Assertion failed" is used. The
2080 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2081 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2082 assembler if possible, and in any case, it's also passed to the linker in
2083 the object file (if one is generated). The linker will then evaluate the
2084 expression when segment placement has been done.
2089 .assert * = $8000, error, "Code not at $8000"
2092 The example assertion will check that the current location is at $8000,
2093 when the output file is written, and abort with an error if this is not
2094 the case. More complex expressions are possible. The action specifier
2095 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2096 an error message. In the latter case, generation of the output file is
2097 suppressed in both the assembler and linker.
2100 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2102 Is followed by a plus or a minus character. When switched on (using a
2103 +), undefined symbols are automatically marked as import instead of
2104 giving errors. When switched off (which is the default so this does not
2105 make much sense), this does not happen and an error message is
2106 displayed. The state of the autoimport flag is evaluated when the
2107 complete source was translated, before outputting actual code, so it is
2108 <em/not/ possible to switch this feature on or off for separate sections
2109 of code. The last setting is used for all symbols.
2111 You should probably not use this switch because it delays error
2112 messages about undefined symbols until the link stage. The cc65
2113 compiler (which is supposed to produce correct assembler code in all
2114 circumstances, something which is not true for most assembler
2115 programmers) will insert this command to avoid importing each and every
2116 routine from the runtime library.
2121 .autoimport + ; Switch on auto import
2124 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2126 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2127 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2128 the operator '^' prepended to each expression in its list.
2133 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2135 TableLookupLo: .lobytes MyTable
2136 TableLookupHi: .hibytes MyTable
2137 TableLookupBank: .bankbytes MyTable
2140 which is equivalent to
2143 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2144 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2145 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2148 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2149 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2150 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2153 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2155 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2156 so this is a shortcut for
2162 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2165 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2167 Define byte sized data. Must be followed by a sequence of (byte ranged)
2168 expressions or strings.
2174 .byt "world", $0D, $00
2178 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2180 Switch on or off case sensitivity on identifiers. The default is off
2181 (that is, identifiers are case sensitive), but may be changed by the
2182 -i switch on the command line.
2183 The command must be followed by a '+' or '-' character to switch the
2184 option on or off respectively.
2189 .case - ; Identifiers are not case sensitive
2193 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2195 Apply a custom mapping for characters. The command is followed by two
2196 numbers. The first one is the index of the source character (range 0..255);
2197 the second one is the mapping (range 0..255). The mapping applies to all
2198 character and string constants <em/when/ they generate output; and, overrides
2199 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2200 command line switch.
2204 .charmap $41, $61 ; Map 'A' to 'a'
2208 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2210 Switch to the CODE segment. The name of the CODE segment is always
2211 "CODE", so this is a shortcut for
2217 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2220 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2222 Export a symbol and mark it in a special way. The linker is able to build
2223 tables of all such symbols. This may be used to automatically create a list
2224 of functions needed to initialize linked library modules.
2226 Note: The linker has a feature to build a table of marked routines, but it
2227 is your code that must call these routines, so just declaring a symbol with
2228 <tt/.CONDES/ does nothing by itself.
2230 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2231 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2232 is implied by <tt/.CONDES/.
2234 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2235 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2236 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2237 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2238 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2239 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2240 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2242 After the type, an optional priority may be specified. Higher numeric values
2243 mean higher priority. If no priority is given, the default priority of 7 is
2244 used. Be careful when assigning priorities to your own module constructors
2245 so they won't interfere with the ones in the cc65 library.
2250 .condes ModuleInit, constructor
2251 .condes ModInit, 0, 16
2254 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2255 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2256 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2257 name="Module constructors/destructors"> explaining the feature in more
2261 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2263 Export a symbol and mark it as a module constructor. This may be used
2264 together with the linker to build a table of constructor subroutines that
2265 are called by the startup code.
2267 Note: The linker has a feature to build a table of marked routines, but it
2268 is your code that must call these routines, so just declaring a symbol as
2269 constructor does nothing by itself.
2271 A constructor is always exported as an absolute (16 bit) symbol. You don't
2272 need to use an additional <tt/.export/ statement, this is implied by
2273 <tt/.constructor/. It may have an optional priority that is separated by a
2274 comma. Higher numeric values mean a higher priority. If no priority is
2275 given, the default priority of 7 is used. Be careful when assigning
2276 priorities to your own module constructors so they won't interfere with the
2277 ones in the cc65 library.
2282 .constructor ModuleInit
2283 .constructor ModInit, 16
2286 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2287 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2288 <ref id="condes" name="Module constructors/destructors"> explaining the
2289 feature in more detail.
2292 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2294 Switch to the DATA segment. The name of the DATA segment is always
2295 "DATA", so this is a shortcut for
2301 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2304 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2306 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2307 create word sized data in native 65XX format). Must be followed by a
2308 sequence of (word ranged) expressions.
2316 This will emit the bytes
2322 into the current segment in that order.
2325 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2327 Switch on or off debug info generation. The default is off (that is,
2328 the object file will not contain debug infos), but may be changed by the
2329 -g switch on the command line.
2330 The command must be followed by a '+' or '-' character to switch the
2331 option on or off respectively.
2336 .debuginfo + ; Generate debug info
2340 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2342 Start a define style macro definition. The command is followed by an
2343 identifier (the macro name) and optionally by a list of formal arguments
2346 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2347 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2350 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2351 section <ref id="macros" name="Macros">.
2354 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2356 Delete a classic macro (defined with <tt><ref id=".MACRO"
2357 name=".MACRO"></tt>) . The command is followed by the name of an
2358 existing macro. Its definition will be deleted together with the name.
2359 If necessary, another macro with this name may be defined later.
2361 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2362 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2363 <tt><ref id=".MACRO" name=".MACRO"></tt>
2365 See also section <ref id="macros" name="Macros">.
2368 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2370 Builtin function. The function expects an identifier as argument in braces.
2371 The argument is evaluated, and the function yields "true" if the identifier
2372 is a symbol that is already defined somewhere in the source file up to the
2373 current position. Otherwise the function yields false. As an example, the
2374 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2381 <sect1><tt>.DEFINEDMACRO</tt><label id=".DEFINEDMACRO"><p>
2383 Builtin function. The function expects an identifier as argument in braces.
2384 The argument is evaluated, and the function yields "true" if the identifier
2385 has already been defined as the name of a macro. Otherwise the function yields
2394 .if .definedmacro(add)
2403 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2405 Export a symbol and mark it as a module destructor. This may be used
2406 together with the linker to build a table of destructor subroutines that
2407 are called by the startup code.
2409 Note: The linker has a feature to build a table of marked routines, but it
2410 is your code that must call these routines, so just declaring a symbol as
2411 constructor does nothing by itself.
2413 A destructor is always exported as an absolute (16 bit) symbol. You don't
2414 need to use an additional <tt/.export/ statement, this is implied by
2415 <tt/.destructor/. It may have an optional priority that is separated by a
2416 comma. Higher numerical values mean a higher priority. If no priority is
2417 given, the default priority of 7 is used. Be careful when assigning
2418 priorities to your own module destructors so they won't interfere with the
2419 ones in the cc65 library.
2424 .destructor ModuleDone
2425 .destructor ModDone, 16
2428 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2429 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2430 section <ref id="condes" name="Module constructors/destructors"> explaining
2431 the feature in more detail.
2434 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2436 Define dword sized data (4 bytes) Must be followed by a sequence of
2442 .dword $12344512, $12FA489
2446 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2448 Conditional assembly: Reverse the current condition.
2451 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2453 Conditional assembly: Reverse current condition and test a new one.
2456 <sect1><tt>.END</tt><label id=".END"><p>
2458 Forced end of assembly. Assembly stops at this point, even if the command
2459 is read from an include file.
2462 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2464 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2467 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2469 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2470 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2473 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2475 Marks the end of a macro definition.
2477 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2478 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2479 <tt><ref id=".MACRO" name=".MACRO"></tt>
2481 See also section <ref id="macros" name="Macros">.
2484 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2486 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2489 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2491 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2494 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2496 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2499 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2501 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2502 command and the separate section named <ref id="structs" name=""Structs
2506 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2508 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2509 command and the separate section named <ref id="structs" name=""Structs
2513 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2515 Start an enumeration. This directive is very similar to the C <tt/enum/
2516 keyword. If a name is given, a new scope is created for the enumeration,
2517 otherwise the enumeration members are placed in the enclosing scope.
2519 In the enumeration body, symbols are declared. The first symbol has a value
2520 of zero, and each following symbol will get the value of the preceding plus
2521 one. This behaviour may be overridden by an explicit assignment. Two symbols
2522 may have the same value.
2534 Above example will create a new scope named <tt/errorcodes/ with three
2535 symbols in it that get the values 0, 1 and 2 respectively. Another way
2536 to write this would have been:
2546 Please note that explicit scoping must be used to access the identifiers:
2549 .word errorcodes::no_error
2552 A more complex example:
2561 EWOULDBLOCK = EAGAIN
2565 In this example, the enumeration does not have a name, which means that the
2566 members will be visible in the enclosing scope and can be used in this scope
2567 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2568 The value for the following members is incremented by one, so <tt/EOK/ would
2569 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2570 override for the value using an already defined symbol.
2573 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2575 Force an assembly error. The assembler will output an error message
2576 preceded by "User error". Assembly is continued but no object file will
2579 This command may be used to check for initial conditions that must be
2580 set before assembling a source file.
2590 .error "Must define foo or bar!"
2594 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2595 <tt><ref id=".OUT" name=".OUT"></tt>,
2596 <tt><ref id=".WARNING" name=".WARNING"></tt>
2599 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2601 Abort a macro expansion immediately. This command is often useful in
2604 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2605 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2606 <tt><ref id=".MACRO" name=".MACRO"></tt>
2608 See also section <ref id="macros" name="Macros">.
2611 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2613 Make symbols accessible from other modules. Must be followed by a comma
2614 separated list of symbols to export, with each one optionally followed by an
2615 address specification and (also optional) an assignment. Using an additional
2616 assignment in the export statement allows to define and export a symbol in
2617 one statement. The default is to export the symbol with the address size it
2618 actually has. The assembler will issue a warning, if the symbol is exported
2619 with an address size smaller than the actual address size.
2626 .export foobar: far = foo * bar
2627 .export baz := foobar, zap: far = baz - bar
2630 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2633 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2636 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2638 Make symbols accessible from other modules. Must be followed by a comma
2639 separated list of symbols to export. The exported symbols are explicitly
2640 marked as zero page symbols. An assignment may be included in the
2641 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2648 .exportzp baz := $02
2651 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2654 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2656 Define far (24 bit) address data. The command must be followed by a
2657 sequence of (not necessarily constant) expressions.
2662 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2665 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2668 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2670 Force an assembly error and terminate assembly. The assembler will output an
2671 error message preceded by "User error" and will terminate assembly
2674 This command may be used to check for initial conditions that must be
2675 set before assembling a source file.
2685 .fatal "Must define foo or bar!"
2689 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2690 <tt><ref id=".OUT" name=".OUT"></tt>,
2691 <tt><ref id=".WARNING" name=".WARNING"></tt>
2694 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2696 This directive may be used to enable one or more compatibility features
2697 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2698 possible, it may be useful when porting sources written for other
2699 assemblers. There is no way to switch a feature off, once you have
2700 enabled it, so using
2706 will enable the feature until end of assembly is reached.
2708 The following features are available:
2712 <tag><tt>addrsize</tt><label id="addrsize"></tag>
2714 Enables the .ADDRSIZE pseudo function. This function is experimental and not enabled by default.
2716 See also: <tt><ref id=".ADDRSIZE" name=".ADDRSIZE"></tt>
2718 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2720 Accept the at character (`@') as a valid character in identifiers. The
2721 at character is not allowed to start an identifier, even with this
2724 <tag><tt>bracket_as_indirect</tt><label id="bracket_as_indirect"></tag>
2726 Use <tt>[]</tt> instead of <tt>()</tt> for the indirect addressing modes.
2736 <em/Note:/ This should not be used in 65186 mode because it conflicts with
2737 the 65816 instruction syntax for far addressing. See the section covering
2738 <tt/<ref id="address-sizes" name="address sizes">/ for more information.
2740 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2742 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2743 comment terminators. Note that C comments may not be nested. There's also a
2744 pitfall when using C like comments: All statements must be terminated by
2745 "end-of-line". Using C like comments, it is possible to hide the newline,
2746 which results in error messages. See the following non working example:
2749 lda #$00 /* This comment hides the newline
2753 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2755 Accept the dollar sign (`$') as a valid character in identifiers. The
2756 dollar character is not allowed to start an identifier, even with this
2759 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2761 The dollar sign may be used as an alias for the star (`*'), which
2762 gives the value of the current PC in expressions.
2763 Note: Assignment to the pseudo variable is not allowed.
2765 <tag><tt>force_range</tt><label id="force_range"></tag>
2767 Force expressions into their valid range for immediate addressing and
2768 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2769 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2770 since it will completely disable error checks.
2772 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2774 Allow labels without a trailing colon. These labels are only accepted,
2775 if they start at the beginning of a line (no leading white space).
2777 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2779 Accept the dot (`.') as the first character of an identifier. This may be
2780 used for example to create macro names that start with a dot emulating
2781 control directives of other assemblers. Note however, that none of the
2782 reserved keywords built into the assembler, that starts with a dot, may be
2783 overridden. When using this feature, you may also get into trouble if
2784 later versions of the assembler define new keywords starting with a dot.
2786 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2788 Accept single quotes as well as double quotes as terminators for char
2791 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2793 Accept single quotes as well as double quotes as terminators for string
2796 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2798 Accept single quoted character constants where the terminating quote is
2803 <em/Note:/ This does not work in conjunction with <tt/.FEATURE
2804 loose_string_term/, since in this case the input would be ambiguous.
2806 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2808 This feature makes relocatable/absolute mode local to the current segment.
2809 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2810 effect will only enable absolute mode for the current segment. Dito for
2811 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2813 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2815 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2816 is enabled). Such an assignment is handled identical to the <tt><ref
2817 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2818 removing the lines with the assignments may also be an option when porting
2819 code written for older assemblers).
2821 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2823 Allow the use of instructions names as names for macros and symbols. This
2824 makes it possible to "overload" instructions by defining a macro with the
2825 same name. This does also make it possible to introduce hard to find errors
2826 in your code, so be careful!
2828 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2830 Allow underlines within numeric constants. These may be used for grouping
2831 the digits of numbers for easier reading.
2834 .feature underline_in_numbers
2835 .word %1100001110100101
2836 .word %1100_0011_1010_0101 ; Identical but easier to read
2841 It is also possible to specify features on the command line using the
2842 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2843 This is useful when translating sources written for older assemblers, when
2844 you don't want to change the source code.
2846 As an example, to translate sources written for Andre Fachats xa65
2847 assembler, the features
2850 labels_without_colons, pc_assignment, loose_char_term
2853 may be helpful. They do not make ca65 completely compatible, so you may not
2854 be able to translate the sources without changes, even when enabling these
2855 features. However, I have found several sources that translate without
2856 problems when enabling these features on the command line.
2859 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2861 Insert an option string into the object file. There are two forms of
2862 this command, one specifies the option by a keyword, the second
2863 specifies it as a number. Since usage of the second one needs knowledge
2864 of the internal encoding, its use is not recommended and I will only
2865 describe the first form here.
2867 The command is followed by one of the keywords
2875 a comma and a string. The option is written into the object file
2876 together with the string value. This is currently unidirectional and
2877 there is no way to actually use these options once they are in the
2883 .fileopt comment, "Code stolen from my brother"
2884 .fileopt compiler, "BASIC 2.0"
2885 .fopt author, "J. R. User"
2889 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2891 Import an absolute symbol from another module. The command is followed by a
2892 comma separated list of symbols to import. The command is similar to <tt>
2893 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2894 written to the generated object file, even if the symbol is never referenced
2895 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2896 references for unused symbols).
2901 .forceimport needthisone, needthistoo
2904 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2907 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2909 Declare symbols as global. Must be followed by a comma separated list of
2910 symbols to declare. Symbols from the list, that are defined somewhere in the
2911 source, are exported, all others are imported. Additional <tt><ref
2912 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2913 name=".EXPORT"></tt> commands for the same symbol are allowed.
2922 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2924 Declare symbols as global. Must be followed by a comma separated list of
2925 symbols to declare. Symbols from the list, that are defined somewhere in the
2926 source, are exported, all others are imported. Additional <tt><ref
2927 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2928 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2929 in the list are explicitly marked as zero page symbols.
2937 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2939 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2940 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2941 the operator '>' prepended to each expression in its list.
2946 .lobytes $1234, $2345, $3456, $4567
2947 .hibytes $fedc, $edcb, $dcba, $cba9
2950 which is equivalent to
2953 .byte $34, $45, $56, $67
2954 .byte $fe, $ed, $dc, $cb
2960 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2962 TableLookupLo: .lobytes MyTable
2963 TableLookupHi: .hibytes MyTable
2966 which is equivalent to
2969 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2970 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2973 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2974 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2975 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2978 <sect1><tt>.I16</tt><label id=".I16"><p>
2980 Valid only in 65816 mode. Switch the index registers to 16 bit.
2982 Note: This command will not emit any code, it will tell the assembler to
2983 create 16 bit operands for immediate operands.
2985 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2986 name=".SMART"></tt> commands.
2989 <sect1><tt>.I8</tt><label id=".I8"><p>
2991 Valid only in 65816 mode. Switch the index registers to 8 bit.
2993 Note: This command will not emit any code, it will tell the assembler to
2994 create 8 bit operands for immediate operands.
2996 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2997 name=".SMART"></tt> commands.
3000 <sect1><tt>.IF</tt><label id=".IF"><p>
3002 Conditional assembly: Evaluate an expression and switch assembler output
3003 on or off depending on the expression. The expression must be a constant
3004 expression, that is, all operands must be defined.
3006 A expression value of zero evaluates to FALSE, any other value evaluates
3010 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
3012 Conditional assembly: Check if there are any remaining tokens in this line,
3013 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
3014 condition is not true, further lines are not assembled until an <tt><ref
3015 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3016 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3018 This command is often used to check if a macro parameter was given. Since an
3019 empty macro parameter will evaluate to nothing, the condition will evaluate
3020 to TRUE if an empty parameter was given.
3034 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3037 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
3039 Conditional assembly: Evaluate an expression and switch assembler output
3040 on or off depending on the constness of the expression.
3042 A const expression evaluates to to TRUE, a non const expression (one
3043 containing an imported or currently undefined symbol) evaluates to
3046 See also: <tt><ref id=".CONST" name=".CONST"></tt>
3049 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
3051 Conditional assembly: Check if a symbol is defined. Must be followed by
3052 a symbol name. The condition is true if the the given symbol is already
3053 defined, and false otherwise.
3055 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3058 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
3060 Conditional assembly: Check if there are any remaining tokens in this line,
3061 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
3062 condition is not true, further lines are not assembled until an <tt><ref
3063 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3064 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3066 This command is often used to check if a macro parameter was given.
3067 Since an empty macro parameter will evaluate to nothing, the condition
3068 will evaluate to FALSE if an empty parameter was given.
3081 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3084 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
3086 Conditional assembly: Check if a symbol is defined. Must be followed by
3087 a symbol name. The condition is true if the the given symbol is not
3088 defined, and false otherwise.
3090 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3093 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
3095 Conditional assembly: Check if a symbol is referenced. Must be followed
3096 by a symbol name. The condition is true if if the the given symbol was
3097 not referenced before, and false otherwise.
3099 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3102 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
3104 Conditional assembly: Check if the assembler is currently in 6502 mode
3105 (see <tt><ref id=".P02" name=".P02"></tt> command).
3108 <sect1><tt>.IFP4510</tt><label id=".IFP4510"><p>
3110 Conditional assembly: Check if the assembler is currently in 4510 mode
3111 (see <tt><ref id=".P4510" name=".P4510"></tt> command).
3114 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
3116 Conditional assembly: Check if the assembler is currently in 65816 mode
3117 (see <tt><ref id=".P816" name=".P816"></tt> command).
3120 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
3122 Conditional assembly: Check if the assembler is currently in 65C02 mode
3123 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3126 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3128 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3129 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3132 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3134 Conditional assembly: Check if a symbol is referenced. Must be followed
3135 by a symbol name. The condition is true if if the the given symbol was
3136 referenced before, and false otherwise.
3138 This command may be used to build subroutine libraries in include files
3139 (you may use separate object modules for this purpose too).
3144 .ifref ToHex ; If someone used this subroutine
3145 ToHex: tay ; Define subroutine
3151 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3154 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3156 Import a symbol from another module. The command is followed by a comma
3157 separated list of symbols to import, with each one optionally followed by
3158 an address specification.
3164 .import bar: zeropage
3167 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3170 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3172 Import a symbol from another module. The command is followed by a comma
3173 separated list of symbols to import. The symbols are explicitly imported
3174 as zero page symbols (that is, symbols with values in byte range).
3182 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3185 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3187 Include a file as binary data. The command expects a string argument
3188 that is the name of a file to include literally in the current segment.
3189 In addition to that, a start offset and a size value may be specified,
3190 separated by commas. If no size is specified, all of the file from the
3191 start offset to end-of-file is used. If no start position is specified
3192 either, zero is assumed (which means that the whole file is inserted).
3197 ; Include whole file
3198 .incbin "sprites.dat"
3200 ; Include file starting at offset 256
3201 .incbin "music.dat", $100
3203 ; Read 100 bytes starting at offset 200
3204 .incbin "graphics.dat", 200, 100
3208 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3210 Include another file. Include files may be nested up to a depth of 16.
3219 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3221 Export a symbol and mark it as an interruptor. This may be used together
3222 with the linker to build a table of interruptor subroutines that are called
3225 Note: The linker has a feature to build a table of marked routines, but it
3226 is your code that must call these routines, so just declaring a symbol as
3227 interruptor does nothing by itself.
3229 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3230 need to use an additional <tt/.export/ statement, this is implied by
3231 <tt/.interruptor/. It may have an optional priority that is separated by a
3232 comma. Higher numeric values mean a higher priority. If no priority is
3233 given, the default priority of 7 is used. Be careful when assigning
3234 priorities to your own module constructors so they won't interfere with the
3235 ones in the cc65 library.
3240 .interruptor IrqHandler
3241 .interruptor Handler, 16
3244 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3245 section <ref id="condes" name="Module constructors/destructors"> explaining
3246 the feature in more detail.
3249 <sect1><tt>.ISMNEM, .ISMNEMONIC</tt><label id=".ISMNEMONIC"><p>
3251 Builtin function. The function expects an identifier as argument in braces.
3252 The argument is evaluated, and the function yields "true" if the identifier
3253 is defined as an instruction mnemonic that is recognized by the assembler.
3257 .if .not .ismnemonic(ina)
3266 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3268 Switch on or off line continuations using the backslash character
3269 before a newline. The option is off by default.
3270 Note: Line continuations do not work in a comment. A backslash at the
3271 end of a comment is treated as part of the comment and does not trigger
3273 The command must be followed by a '+' or '-' character to switch the
3274 option on or off respectively.
3279 .linecont + ; Allow line continuations
3282 #$20 ; This is legal now
3286 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3288 Enable output to the listing. The command must be followed by a boolean
3289 switch ("on", "off", "+" or "-") and will enable or disable listing
3291 The option has no effect if the listing is not enabled by the command line
3292 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3293 to the listing file, if the counter is greater than zero, and suppressed if
3294 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3300 .list on ; Enable listing output
3304 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3306 Set, how many bytes are shown in the listing for one source line. The
3307 default is 12, so the listing will show only the first 12 bytes for any
3308 source line that generates more than 12 bytes of code or data.
3309 The directive needs an argument, which is either "unlimited", or an
3310 integer constant in the range 4..255.
3315 .listbytes unlimited ; List all bytes
3316 .listbytes 12 ; List the first 12 bytes
3317 .incbin "data.bin" ; Include large binary file
3321 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3323 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3324 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3325 the operator '<' prepended to each expression in its list.
3330 .lobytes $1234, $2345, $3456, $4567
3331 .hibytes $fedc, $edcb, $dcba, $cba9
3334 which is equivalent to
3337 .byte $34, $45, $56, $67
3338 .byte $fe, $ed, $dc, $cb
3344 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3346 TableLookupLo: .lobytes MyTable
3347 TableLookupHi: .hibytes MyTable
3350 which is equivalent to
3353 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3354 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3357 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3358 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3359 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3362 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3364 This command may only be used inside a macro definition. It declares a
3365 list of identifiers as local to the macro expansion.
3367 A problem when using macros are labels: Since they don't change their name,
3368 you get a "duplicate symbol" error if the macro is expanded the second time.
3369 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3370 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3373 Some other assemblers start a new lexical block inside a macro expansion.
3374 This has some drawbacks however, since that will not allow <em/any/ symbol
3375 to be visible outside a macro, a feature that is sometimes useful. The
3376 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3377 to address the problem.
3379 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3383 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3385 Defines the character that start "cheap" local labels. You may use one
3386 of '@' and '?' as start character. The default is '@'.
3388 Cheap local labels are labels that are visible only between two non
3389 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3390 using explicit lexical nesting.
3397 Clear: lda #$00 ; Global label
3398 ?Loop: sta Mem,y ; Local label
3402 Sub: ... ; New global label
3403 bne ?Loop ; ERROR: Unknown identifier!
3407 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3409 Insert a predefined macro package. The command is followed by an
3410 identifier specifying the macro package to insert. Available macro
3414 atari Defines the scrcode macro.
3415 cbm Defines the scrcode macro.
3416 cpu Defines constants for the .CPU variable.
3417 generic Defines generic macroes like add, sub, and blt.
3418 longbranch Defines conditional long-jump macroes.
3421 Including a macro package twice, or including a macro package that
3422 redefines already existing macros will lead to an error.
3427 .macpack longbranch ; Include macro package
3429 cmp #$20 ; Set condition codes
3430 jne Label ; Jump long on condition
3433 Macro packages are explained in more detail in section <ref
3434 id="macropackages" name="Macro packages">.
3437 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3439 Start a classic macro definition. The command is followed by an identifier
3440 (the macro name) and optionally by a comma separated list of identifiers
3441 that are macro parameters. A macro definition is terminated by <tt><ref
3442 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3447 .macro ldax arg ; Define macro ldax
3452 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3453 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3454 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3456 See also section <ref id="macros" name="Macros">.
3459 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3461 Start a section of absolute code. The command is followed by a constant
3462 expression that gives the new PC counter location for which the code is
3463 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3466 By default, absolute/relocatable mode is global (valid even when switching
3467 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3468 it can be made segment local.
3470 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3471 code at a specific address is the job of the linker, not the assembler, so
3472 there is usually no reason to assemble code to a specific address.
3477 .org $7FF ; Emit code starting at $7FF
3481 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3483 Output a string to the console without producing an error. This command
3484 is similar to <tt/.ERROR/, however, it does not force an assembler error
3485 that prevents the creation of an object file.
3490 .out "This code was written by the codebuster(tm)"
3493 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3494 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3495 <tt><ref id=".WARNING" name=".WARNING"></tt>
3498 <sect1><tt>.P02</tt><label id=".P02"><p>
3500 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3501 instructions. This is the default if not overridden by the
3502 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3504 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3505 name=".PSC02"></tt>, <tt><ref id=".P816" name=".P816"></tt> and
3506 <tt><ref id=".P4510" name=".P4510"></tt>
3509 <sect1><tt>.P4510</tt><label id=".P4510"><p>
3511 Enable the 4510 instruction set. This is a superset of the 65C02 and
3512 6502 instruction sets.
3514 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3515 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt> and
3516 <tt><ref id=".P816" name=".P816"></tt>
3519 <sect1><tt>.P816</tt><label id=".P816"><p>
3521 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3522 6502 instruction sets.
3524 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3525 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt> and
3526 <tt><ref id=".P4510" name=".P4510"></tt>
3529 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3531 Set the page length for the listing. Must be followed by an integer
3532 constant. The value may be "unlimited", or in the range 32 to 127. The
3533 statement has no effect if no listing is generated. The default value is -1
3534 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3535 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3536 after assembly is complete, you cannot use multiple line lengths with one
3537 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3542 .pagelength 66 ; Use 66 lines per listing page
3544 .pagelength unlimited ; Unlimited page length
3548 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3550 Enable the 65C02 instructions set. This instruction set includes all
3551 6502 and 65SC02 instructions.
3553 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3554 name=".PSC02"></tt>, <tt><ref id=".P816" name=".P816"></tt> and
3555 <tt><ref id=".P4510" name=".P4510"></tt>
3558 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3560 Pop the last CPU setting from the stack, and activate it.
3562 This command will switch back to the CPU that was last pushed onto the CPU
3563 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3564 remove this entry from the stack.
3566 The assembler will print an error message if the CPU stack is empty when
3567 this command is issued.
3569 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3570 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3573 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3575 Pop the last pushed segment from the stack, and set it.
3577 This command will switch back to the segment that was last pushed onto the
3578 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3579 command, and remove this entry from the stack.
3581 The assembler will print an error message if the segment stack is empty
3582 when this command is issued.
3584 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3587 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3589 Start a nested lexical level with the given name and adds a symbol with this
3590 name to the enclosing scope. All new symbols from now on are in the local
3591 lexical level and are accessible from outside only via <ref id="scopesyntax"
3592 name="explicit scope specification">. Symbols defined outside this local
3593 level may be accessed as long as their names are not used for new symbols
3594 inside the level. Symbols names in other lexical levels do not clash, so you
3595 may use the same names for identifiers. The lexical level ends when the
3596 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3597 may be nested up to a depth of 16 (this is an artificial limit to protect
3598 against errors in the source).
3600 Note: Macro names are always in the global level and in a separate name
3601 space. There is no special reason for this, it's just that I've never
3602 had any need for local macro definitions.
3607 .proc Clear ; Define Clear subroutine, start new level
3609 L1: sta Mem,y ; L1 is local and does not cause a
3610 ; duplicate symbol error if used in other
3613 bne L1 ; Reference local symbol
3615 .endproc ; Leave lexical level
3618 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3622 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3624 Enable the 65SC02 instructions set. This instruction set includes all
3627 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3628 name=".PC02"></tt>, <tt><ref id=".P816" name=".P816"></tt> and
3629 <tt><ref id=".P4510" name=".P4510"></tt>
3632 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3634 Push the currently active CPU onto a stack. The stack has a size of 8
3637 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3638 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3639 later, without knowledge of the current CPU setting.
3641 The assembler will print an error message if the CPU stack is already full,
3642 when this command is issued.
3644 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3645 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3648 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3650 Push the currently active segment onto a stack. The entries on the stack
3651 include the name of the segment and the segment type. The stack has a size
3654 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3655 to switch to another segment and to restore the old segment later, without
3656 even knowing the name and type of the current segment.
3658 The assembler will print an error message if the segment stack is already
3659 full, when this command is issued.
3661 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3664 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3666 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3667 name=".ORG"></tt> command.
3670 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3672 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3673 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3674 a constant expression that tells how many times the commands in the body
3675 should get repeated. Optionally, a comma and an identifier may be specified.
3676 If this identifier is found in the body of the repeat statement, it is
3677 replaced by the current repeat count (starting with zero for the first time
3678 the body is repeated).
3680 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3681 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3682 level will be used, not the one from the outer level.
3686 The following macro will emit a string that is "encrypted" in that all
3687 characters of the string are XORed by the value $55.
3691 .repeat .strlen(Arg), I
3692 .byte .strat(Arg, I) ^ $55
3697 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3700 <sect1><tt>.RES</tt><label id=".RES"><p>
3702 Reserve storage. The command is followed by one or two constant
3703 expressions. The first one is mandatory and defines, how many bytes of
3704 storage should be defined. The second, optional expression must by a
3705 constant byte value that will be used as value of the data. If there
3706 is no fill value given, the linker will use the value defined in the
3707 linker configuration file (default: zero).
3712 ; Reserve 12 bytes of memory with value $AA
3717 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3719 Switch to the RODATA segment. The name of the RODATA segment is always
3720 "RODATA", so this is a shortcut for
3726 The RODATA segment is a segment that is used by the compiler for
3727 readonly data like string constants.
3729 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3732 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3734 Start a nested lexical level with the given name. All new symbols from now
3735 on are in the local lexical level and are accessible from outside only via
3736 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3737 outside this local level may be accessed as long as their names are not used
3738 for new symbols inside the level. Symbols names in other lexical levels do
3739 not clash, so you may use the same names for identifiers. The lexical level
3740 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3741 read. Lexical levels may be nested up to a depth of 16 (this is an
3742 artificial limit to protect against errors in the source).
3744 Note: Macro names are always in the global level and in a separate name
3745 space. There is no special reason for this, it's just that I've never
3746 had any need for local macro definitions.
3751 .scope Error ; Start new scope named Error
3753 File = 1 ; File error
3754 Parse = 2 ; Parse error
3755 .endscope ; Close lexical level
3758 lda #Error::File ; Use symbol from scope Error
3761 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3765 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3767 Switch to another segment. Code and data is always emitted into a
3768 segment, that is, a named section of data. The default segment is
3769 "CODE". There may be up to 254 different segments per object file
3770 (and up to 65534 per executable). There are shortcut commands for
3771 the most common segments ("ZEROPAGE", "CODE", "RODATA", "DATA", and "BSS").
3773 The command is followed by a string containing the segment name (there are
3774 some constraints for the name - as a rule of thumb use only those segment
3775 names that would also be valid identifiers). There may also be an optional
3776 address size separated by a colon. See the section covering <tt/<ref
3777 id="address-sizes" name="address sizes">/ for more information.
3779 The default address size for a segment depends on the memory model specified
3780 on the command line. The default is "absolute", which means that you don't
3781 have to use an address size modifier in most cases.
3783 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3784 That is, the segment will reside somewhere in core memory outside the zero
3785 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3786 page and direct (short) addressing is possible for data in this segment.
3788 Beware: Only labels in a segment with the zeropage attribute are marked
3789 as reachable by short addressing. The `*' (PC counter) operator will
3790 work as in other segments and will create absolute variable values.
3792 Please note that a segment cannot have two different address sizes. A
3793 segment specified as zeropage cannot be declared as being absolute later.
3798 .segment "ROM2" ; Switch to ROM2 segment
3799 .segment "ZP2": zeropage ; New direct segment
3800 .segment "ZP2" ; Ok, will use last attribute
3801 .segment "ZP2": absolute ; Error, redecl mismatch
3804 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3805 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt>, <tt><ref
3806 id=".RODATA" name=".RODATA"></tt>, and <tt><ref id=".ZEROPAGE"
3807 name=".ZEROPAGE"></tt>
3810 <sect1><tt>.SET</tt><label id=".SET"><p>
3812 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3813 name="Numeric variables"> for a full description.
3816 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3818 Switch the CPU instruction set. The command is followed by a string that
3819 specifies the CPU. Possible values are those that can also be supplied to
3820 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3821 namely: 6502, 6502X, 65SC02, 65C02, 65816, 4510 and HuC6280.
3823 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3824 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3825 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3826 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3827 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3828 <tt><ref id=".P02" name=".P02"></tt>,
3829 <tt><ref id=".P816" name=".P816"></tt>,
3830 <tt><ref id=".P4510" name=".P4510"></tt>,
3831 <tt><ref id=".PC02" name=".PC02"></tt>,
3832 <tt><ref id=".PSC02" name=".PSC02"></tt>
3835 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3837 Switch on or off smart mode. The command must be followed by a '+' or '-'
3838 character to switch the option on or off respectively. The default is off
3839 (that is, the assembler doesn't try to be smart), but this default may be
3840 changed by the -s switch on the command line.
3842 In smart mode the assembler will do the following:
3845 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3846 and update the operand sizes accordingly. If the operand of such an
3847 instruction cannot be evaluated by the assembler (for example, because
3848 the operand is an imported symbol), a warning is issued. Beware: Since
3849 the assembler cannot trace the execution flow this may lead to false
3850 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3851 instructions to tell the assembler about the current settings.
3852 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3853 used within a procedure declared as <tt/far/, or if the procedure has
3854 no explicit address specification, but it is <tt/far/ because of the
3862 .smart - ; Stop being smart
3865 See: <tt><ref id=".A16" name=".A16"></tt>,
3866 <tt><ref id=".A8" name=".A8"></tt>,
3867 <tt><ref id=".I16" name=".I16"></tt>,
3868 <tt><ref id=".I8" name=".I8"></tt>
3871 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3873 Starts a struct definition. Structs are covered in a separate section named
3874 <ref id="structs" name=""Structs and unions"">.
3876 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3877 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3878 <tt><ref id=".UNION" name=".UNION"></tt>
3881 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3883 Allocate space for a struct or union.
3894 .tag Point ; Allocate 4 bytes
3898 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3900 Delete a define style macro definition. The command is followed by an
3901 identifier which specifies the name of the macro to delete. Macro
3902 replacement is switched of when reading the token following the command
3903 (otherwise the macro name would be replaced by its replacement list).
3905 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3906 section <ref id="macros" name="Macros">.
3909 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3911 Starts a union definition. Unions are covered in a separate section named
3912 <ref id="structs" name=""Structs and unions"">.
3914 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3915 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3916 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3919 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3921 Force an assembly warning. The assembler will output a warning message
3922 preceded by "User warning". This warning will always be output, even if
3923 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3924 command line option.
3926 This command may be used to output possible problems when assembling
3935 .warning "Forward jump in jne, cannot optimize!"
3945 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3946 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3947 <tt><ref id=".OUT" name=".OUT"></tt>
3950 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3952 Define word sized data. Must be followed by a sequence of (word ranged,
3953 but not necessarily constant) expressions.
3958 .word $0D00, $AF13, _Clear
3962 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3964 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3965 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3969 .segment "ZEROPAGE": zeropage
3972 Because of the "zeropage" attribute, labels declared in this segment are
3973 addressed using direct addressing mode if possible. You <em/must/ instruct
3974 the linker to place this segment somewhere in the address range 0..$FF
3975 otherwise you will get errors.
3977 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3981 <sect>Macros<label id="macros"><p>
3984 <sect1>Introduction<p>
3986 Macros may be thought of as "parametrized super instructions". Macros are
3987 sequences of tokens that have a name. If that name is used in the source
3988 file, the macro is "expanded", that is, it is replaced by the tokens that
3989 were specified when the macro was defined.
3992 <sect1>Macros without parameters<p>
3994 In its simplest form, a macro does not have parameters. Here's an
3998 .macro asr ; Arithmetic shift right
3999 cmp #$80 ; Put bit 7 into carry
4000 ror ; Rotate right with carry
4004 The macro above consists of two real instructions, that are inserted into
4005 the code, whenever the macro is expanded. Macro expansion is simply done
4006 by using the name, like this:
4015 <sect1>Parametrized macros<p>
4017 When using macro parameters, macros can be even more useful:
4031 When calling the macro, you may give a parameter, and each occurrence of
4032 the name "addr" in the macro definition will be replaced by the given
4051 A macro may have more than one parameter, in this case, the parameters
4052 are separated by commas. You are free to give less parameters than the
4053 macro actually takes in the definition. You may also leave intermediate
4054 parameters empty. Empty parameters are replaced by empty space (that is,
4055 they are removed when the macro is expanded). If you have a look at our
4056 macro definition above, you will see, that replacing the "addr" parameter
4057 by nothing will lead to wrong code in most lines. To help you, writing
4058 macros with a variable parameter list, there are some control commands:
4060 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
4061 returns true, if there are any tokens on the remainder of the line. Since
4062 empty parameters are replaced by nothing, this may be used to test if a given
4063 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
4066 Look at this example:
4069 .macro ldaxy a, x, y
4082 That macro may be called as follows:
4085 ldaxy 1, 2, 3 ; Load all three registers
4087 ldaxy 1, , 3 ; Load only a and y
4089 ldaxy , , 3 ; Load y only
4092 There's another helper command for determining which macro parameters are
4093 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>. That command is
4094 replaced by the parameter count given, <em/including/ explicitly empty
4098 ldaxy 1 ; .PARAMCOUNT = 1
4099 ldaxy 1,,3 ; .PARAMCOUNT = 3
4100 ldaxy 1,2 ; .PARAMCOUNT = 2
4101 ldaxy 1, ; .PARAMCOUNT = 2
4102 ldaxy 1,2,3 ; .PARAMCOUNT = 3
4105 Macro parameters may optionally be enclosed into curly braces. This allows the
4106 inclusion of tokens that would otherwise terminate the parameter (the comma in
4107 case of a macro parameter).
4110 .macro foo arg1, arg2
4114 foo ($00,x) ; Two parameters passed
4115 foo {($00,x)} ; One parameter passed
4118 In the first case, the macro is called with two parameters: '<tt/($00/'
4119 and '<tt/x)/'. The comma is not passed to the macro, because it is part of the
4120 calling sequence, not the parameters.
4122 In the second case, '<tt/($00,x)/' is passed to the macro; this time,
4123 including the comma.
4126 <sect1>Detecting parameter types<p>
4128 Sometimes it is nice to write a macro that acts differently depending on the
4129 type of the argument supplied. An example would be a macro that loads a 16 bit
4130 value from either an immediate operand, or from memory. The <tt/<ref
4131 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
4132 functions will allow you to do exactly this:
4136 .if (.match (.left (1, {arg}), #))
4138 lda #<(.right (.tcount ({arg})-1, {arg}))
4139 ldx #>(.right (.tcount ({arg})-1, {arg}))
4141 ; assume absolute or zero page
4148 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4149 check if its argument begins with a hash mark. If so, two immediate loads are
4150 emitted, Otherwise a load from an absolute zero page memory location is
4151 assumed. Please note how the curly braces are used to enclose parameters to
4152 pseudo functions handling token lists. This is necessary, because the token
4153 lists may include commas or parens, which would be treated by the assembler
4156 The macro can be used as
4161 ldax #$1234 ; X=$12, A=$34
4163 ldax foo ; X=$56, A=$78
4167 <sect1>Recursive macros<p>
4169 Macros may be used recursively:
4172 .macro push r1, r2, r3
4181 There's also a special macro command to help with writing recursive macros:
4182 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>. That command will stop macro
4183 expansion immediately:
4186 .macro push r1, r2, r3, r4, r5, r6, r7
4188 ; First parameter is empty
4194 push r2, r3, r4, r5, r6, r7
4198 When expanding that macro, the expansion will push all given parameters
4199 until an empty one is encountered. The macro may be called like this:
4202 push $20, $21, $32 ; Push 3 ZP locations
4203 push $21 ; Push one ZP location
4207 <sect1>Local symbols inside macros<p>
4209 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4210 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4211 Have a look at the inc16 macro above. Here is it again:
4225 If you have a closer look at the code, you will notice, that it could be
4226 written more efficiently, like this:
4237 But imagine what happens, if you use this macro twice? Since the label "Skip"
4238 has the same name both times, you get a "duplicate symbol" error. Without a
4239 way to circumvent this problem, macros are not as useful, as they could be.
4240 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4241 It declares one or more symbols as local to the macro expansion. The names of
4242 local variables are replaced by a unique name in each separate macro
4243 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4247 .local Skip ; Make Skip a local symbol
4251 Skip: ; Not visible outside
4255 Another solution is of course to start a new lexical block inside the macro
4256 that hides any labels:
4270 <sect1>C style macros<p>
4272 Starting with version 2.5 of the assembler, there is a second macro type
4273 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4274 similar to the classic macro type described above, but behaviour is sometimes
4279 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4280 span more than a line. You may use line continuation (see <tt><ref
4281 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4282 more than one line for increased readability, but the macro itself
4283 may not contain an end-of-line token.
4285 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4286 the name space with classic macros, but they are detected and replaced
4287 at the scanner level. While classic macros may be used in every place,
4288 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4289 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4290 they are more versatile in some situations.
4292 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4293 parameters. While classic macros may have empty parameters, this is
4294 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4295 For this macro type, the number of actual parameters must match
4296 exactly the number of formal parameters.
4298 To make this possible, formal parameters are enclosed in braces when
4299 defining the macro. If there are no parameters, the empty braces may
4302 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4303 contain end-of-line tokens, there are things that cannot be done. They
4304 may not contain several processor instructions for example. So, while
4305 some things may be done with both macro types, each type has special
4306 usages. The types complement each other.
4308 <item> Parentheses work differently from C macros.
4309 The common practice of wrapping C macros in parentheses may cause
4310 unintended problems here, such as accidentally implying an
4311 indirect addressing mode. While the definition of a macro requires
4312 parentheses around its argument list, when invoked they should not be
4317 Let's look at a few examples to make the advantages and disadvantages
4320 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4321 following <tt/.DEFINE/:
4326 foo EQU $1234 ; This is accepted now
4329 You may use the directive to define string constants used elsewhere:
4332 ; Define the version number
4333 .define VERSION "12.3a"
4339 Macros with parameters may also be useful:
4342 .define DEBUG(message) .out message
4344 DEBUG "Assembling include file #3"
4347 Note that, while formal parameters have to be placed in parentheses,
4348 the actual argument used when invoking the macro should not be.
4349 The invoked arguments are separated by commas only, if parentheses are
4350 used by accident they will become part of the replaced token.
4352 If you wish to have an expression follow the macro invocation, the
4353 last parameter can be enclosed in curly braces {} to indicate the end of that
4359 .define COMBINE(ta,tb,tc) ta+tb*10+tc*100
4361 .word COMBINE 5,6,7 ; 5+6*10+7*100 = 765
4362 .word COMBINE(5,6,7) ; (5+6*10+7)*100 = 7200 ; incorrect use of parentheses
4363 .word COMBINE 5,6,7+1 ; 5+6*10+7+1*100 = 172
4364 .word COMBINE 5,6,{7}+1 ; 5+6*10+7*100+1 = 766 ; {} encloses the argument
4365 .word COMBINE 5,6-2,7 ; 5+6-2*10+7*100 = 691
4366 .word COMBINE 5,(6-2),7 ; 5+(6-2)*10+7*100 = 745
4367 .word COMBINE 5,6,7+COMBINE 0,1,2 ; 5+6*10+7+0+1*10+2*100*100 = 20082
4368 .word COMBINE 5,6,{7}+COMBINE 0,1,2 ; 5+6*10+7*100+0+1*10+2*100 = 975
4371 With C macros it is common to enclose the results in parentheses to
4372 prevent unintended interactions with the text of the arguments, but
4373 additional care must be taken in this assembly context where parentheses
4374 may alter the meaning of a statement. In particular, indirect addressing modes
4375 may be accidentally implied:
4378 .define DUO(ta,tb) (ta+(tb*10))
4380 lda DUO(5,4), Y ; LDA (indirect), Y
4381 lda 0+DUO(5,4), Y ; LDA absolute indexed, Y
4385 <sect1>Characters in macros<p>
4387 When using the <ref id="option-t" name="-t"> option, characters are translated
4388 into the target character set of the specific machine. However, this happens
4389 as late as possible. This means that strings are translated if they are part
4390 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4391 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4392 used as part of an expression.
4394 This behaviour is very intuitive outside of macros but may be confusing when
4395 doing more complex macros. If you compare characters against numeric values,
4396 be sure to take the translation into account.
4399 <sect1>Deleting macros<p>
4401 Macros can be deleted. This will not work if the macro that should be deleted
4402 is currently expanded as in the following non-working example:
4406 .delmacro notworking
4409 notworking ; Will not work
4412 The commands to delete classic and define style macros differ. Classic macros
4413 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4414 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4415 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4423 .byte value ; Emit one byte with value 1
4424 mac ; Emit another byte with value 2
4429 .byte value ; Error: Unknown identifier
4430 mac ; Error: Missing ":"
4433 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4434 the name of such a macro is replaced by its replacement list on a very low
4435 level. To get the actual name, macro replacement has to be switched off when
4436 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4437 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4438 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4439 different commands increases flexibility.
4443 <sect>Macro packages<label id="macropackages"><p>
4445 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4446 macro packages may be included with just one command. Available macro packages
4450 <sect1><tt>.MACPACK generic</tt><p>
4452 This macro package defines macroes that are useful in almost any program.
4453 Currently defined macroes are:
4456 .macro add Arg ; add without carry
4461 .macro sub Arg ; subtract without borrow
4466 .macro bge Arg ; branch on greater-than or equal
4470 .macro blt Arg ; branch on less-than
4474 .macro bgt Arg ; branch on greater-than
4481 .macro ble Arg ; branch on less-than or equal
4486 .macro bnz Arg ; branch on not zero
4490 .macro bze Arg ; branch on zero
4496 <sect1><tt>.MACPACK longbranch</tt><p>
4498 This macro package defines long conditional jumps. They are named like the
4499 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4500 definition for the "<tt/jeq/" macro, the other macros are built using the same
4505 .if .def(Target) .and ((*+2)-(Target) <= 127)
4514 All macros expand to a short branch, if the label is already defined (back
4515 jump) and is reachable with a short jump. Otherwise the macro expands to a
4516 conditional branch with the branch condition inverted, followed by an absolute
4517 jump to the actual branch target.
4519 The package defines the following macros:
4522 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4527 <sect1><tt>.MACPACK apple2</tt><p>
4529 This macro package defines a macro named <tt/scrcode/. It takes a string
4530 as argument and places this string into memory translated into screen codes.
4533 <sect1><tt>.MACPACK atari</tt><p>
4535 This macro package defines a macro named <tt/scrcode/. It takes a string
4536 as argument and places this string into memory translated into screen codes.
4539 <sect1><tt>.MACPACK cbm</tt><p>
4541 This macro package defines a macro named <tt/scrcode/. It takes a string
4542 as argument and places this string into memory translated into screen codes.
4545 <sect1><tt>.MACPACK cpu</tt><p>
4547 This macro package does not define any macros but constants used to examine
4548 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4549 each supported CPU a constant similar to
4561 is defined. These constants may be used to determine the exact type of the
4562 currently enabled CPU. In addition to that, for each CPU instruction set,
4563 another constant is defined:
4575 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4576 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4577 currently enabled CPU supports a specific instruction set. For example the
4578 65C02 supports all instructions of the 65SC02 CPU, so it has the
4579 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4583 .if (.cpu .bitand CPU_ISET_65SC02)
4591 it is possible to determine if the
4597 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4598 CPUs (the latter two are upwards compatible to the 65SC02).
4601 <sect1><tt>.MACPACK module</tt><p>
4603 This macro package defines a macro named <tt/module_header/. It takes an
4604 identifier as argument and is used to define the header of a module both
4605 in the dynamic and static variant.
4609 <sect>Predefined constants<label id="predefined-constants"><p>
4611 For better orthogonality, the assembler defines similar symbols as the
4612 compiler, depending on the target system selected:
4615 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4616 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4617 <item><tt/__ATARI2600__/ - Target system is <tt/atari2600/
4618 <item><tt/__ATARI5200__/ - Target system is <tt/atari5200/
4619 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4620 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4621 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4622 <item><tt/__BBC__/ - Target system is <tt/bbc/
4623 <item><tt/__C128__/ - Target system is <tt/c128/
4624 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4625 <item><tt/__C64__/ - Target system is <tt/c64/
4626 <item><tt/__CBM__/ - Target is a Commodore system
4627 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4628 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4629 <item><tt/__GEOS__/ - Target is a GEOS system
4630 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4631 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4632 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4633 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4634 <item><tt/__NES__/ - Target system is <tt/nes/
4635 <item><tt/__OSIC1P__/ - Target system is <tt/osic1p/
4636 <item><tt/__PET__/ - Target system is <tt/pet/
4637 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4638 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4639 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4640 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4641 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4645 <sect>Structs and unions<label id="structs"><p>
4647 <sect1>Structs and unions Overview<p>
4649 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4650 are to some degree comparable to their C counterparts. Both have a list of
4651 members. Each member allocates storage and may optionally have a name, which,
4652 in case of a struct, is the offset from the beginning and, in case of a union,
4656 <sect1>Declaration<p>
4658 Here is an example for a very simple struct with two members and a total size
4668 A union shares the total space between all its members, its size is the same
4669 as that of the largest member. The offset of all members relative to the union
4679 A struct or union must not necessarily have a name. If it is anonymous, no
4680 local scope is opened, the identifiers used to name the members are placed
4681 into the current scope instead.
4683 A struct may contain unnamed members and definitions of local structs. The
4684 storage allocators may contain a multiplier, as in the example below:
4689 .word 2 ; Allocate two words
4696 <sect1>The <tt/.TAG/ keyword<p>
4698 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4699 for an already defined struct or unions within another struct:
4713 Space for a struct or union may be allocated using the <ref id=".TAG"
4714 name=".TAG"> directive.
4720 Currently, members are just offsets from the start of the struct or union. To
4721 access a field of a struct, the member offset has to be added to the address
4722 of the struct itself:
4725 lda C+Circle::Radius ; Load circle radius into A
4728 This may change in a future version of the assembler.
4731 <sect1>Limitations<p>
4733 Structs and unions are currently implemented as nested symbol tables (in fact,
4734 they were a by-product of the improved scoping rules). Currently, the
4735 assembler has no idea of types. This means that the <ref id=".TAG"
4736 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4737 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4738 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4739 this structure accessible by using the '::' operator.
4743 <sect>Module constructors/destructors<label id="condes"><p>
4745 <em>Note:</em> This section applies mostly to C programs, so the explanation
4746 below uses examples from the C libraries. However, the feature may also be
4747 useful for assembler programs.
4750 <sect1>Module constructors/destructors Overview<p>
4752 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4753 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4754 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4755 special way. The linker is able to generate tables with all functions of a
4756 specific type. Such a table will <em>only</em> include symbols from object
4757 files that are linked into a specific executable. This may be used to add
4758 initialization and cleanup code for library modules, or a table of interrupt
4761 The C heap functions are an example where module initialization code is used.
4762 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4763 variables that contain the start and the end of the heap, pointers to the free
4764 list and so on. Since the end of the heap depends on the size and start of the
4765 stack, it must be initialized at runtime. However, initializing these
4766 variables for programs that do not use the heap are a waste of time and
4769 So the central module defines a function that contains initialization code and
4770 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4771 this module is added to an executable by the linker, the initialization
4772 function will be placed into the table of constructors by the linker. The C
4773 startup code will call all constructors before <tt/main/ and all destructors
4774 after <tt/main/, so without any further work, the heap initialization code is
4775 called once the module is linked in.
4777 While it would be possible to add explicit calls to initialization functions
4778 in the startup code, the new approach has several advantages:
4782 If a module is not included, the initialization code is not linked in and not
4783 called. So you don't pay for things you don't need.
4786 Adding another library that needs initialization does not mean that the
4787 startup code has to be changed. Before we had module constructors and
4788 destructors, the startup code for all systems had to be adjusted to call the
4789 new initialization code.
4792 The feature saves memory: Each additional initialization function needs just
4793 two bytes in the table (a pointer to the function).
4798 <sect1>Calling order<p>
4800 The symbols are sorted in increasing priority order by the linker when using
4801 one of the builtin linker configurations, so the functions with lower
4802 priorities come first and are followed by those with higher priorities. The C
4803 library runtime subroutine that walks over the function tables calls the
4804 functions starting from the top of the table - which means that functions with
4805 a high priority are called first.
4807 So when using the C runtime, functions are called with high priority functions
4808 first, followed by low priority functions.
4813 When using these special symbols, please take care of the following:
4818 The linker will only generate function tables, it will not generate code to
4819 call these functions. If you're using the feature in some other than the
4820 existing C environments, you have to write code to call all functions in a
4821 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4822 in the C runtime for an example on how to do this.
4825 The linker will only add addresses of functions that are in modules linked to
4826 the executable. This means that you have to be careful where to place the
4827 condes functions. If initialization or an irq handler is needed for a group of
4828 functions, be sure to place the function into a module that is linked in
4829 regardless of which function is called by the user.
4832 The linker will generate the tables only when requested to do so by the
4833 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4834 be requested separately.
4837 Constructors and destructors may have priorities. These priorities determine
4838 the order of the functions in the table. If your initialization or cleanup code
4839 does depend on other initialization or cleanup code, you have to choose the
4840 priority for the functions accordingly.
4843 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4844 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4845 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4846 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4847 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4848 (interruptor). The linker generates a separate table for each type on request.
4853 <sect>Porting sources from other assemblers<p>
4855 Sometimes it is necessary to port code written for older assemblers to ca65.
4856 In some cases, this can be done without any changes to the source code by
4857 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4858 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4861 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4862 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4863 done by the linker. Most other assemblers generate absolute code, placement is
4864 done within the assembler and there is no external linker.
4866 In general it is not a good idea to write new code using the emulation
4867 features of the assembler, but there may be situations where even this rule is
4872 You need to use some of the ca65 emulation features to simulate the behaviour
4873 of such simple assemblers.
4876 <item>Prepare your sourcecode like this:
4879 ; if you want TASS style labels without colons
4880 .feature labels_without_colons
4882 ; if you want TASS style character constants
4883 ; ("a" instead of the default 'a')
4884 .feature loose_char_term
4886 .word *+2 ; the cbm load address
4891 notice that the two emulation features are mostly useful for porting
4892 sources originally written in/for TASS, they are not needed for the
4893 actual "simple assembler operation" and are not recommended if you are
4894 writing new code from scratch.
4896 <item>Replace all program counter assignments (which are not possible in ca65
4897 by default, and the respective emulation feature works different from what
4898 you'd expect) by another way to skip to memory locations, for example the
4899 <tt><ref id=".RES" name=".RES"></tt> directive.
4903 .res $2000-* ; reserve memory up to $2000
4906 Please note that other than the original TASS, ca65 can never move the program
4907 counter backwards - think of it as if you are assembling to disk with TASS.
4909 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4910 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4911 of <tt/.goto/, everything involving loops must be replaced by
4912 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4914 <item>To assemble code to a different address than it is executed at, use the
4915 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4916 <tt/.offs/-constructs.
4923 .reloc ; back to normal
4926 <item>Then assemble like this:
4929 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4932 Note that you need to use the actual start address minus two, since two bytes
4933 are used for the cbm load address.
4940 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4941 Bassewitz. For usage of the binaries and/or sources the following
4942 conditions do apply:
4944 This software is provided 'as-is', without any expressed or implied
4945 warranty. In no event will the authors be held liable for any damages
4946 arising from the use of this software.
4948 Permission is granted to anyone to use this software for any purpose,
4949 including commercial applications, and to alter it and redistribute it
4950 freely, subject to the following restrictions:
4953 <item> The origin of this software must not be misrepresented; you must not
4954 claim that you wrote the original software. If you use this software
4955 in a product, an acknowledgment in the product documentation would be
4956 appreciated but is not required.
4957 <item> Altered source versions must be plainly marked as such, and must not
4958 be misrepresented as being the original software.
4959 <item> This notice may not be removed or altered from any source