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 65618 mnemonics when in 65816 mode (after the
428 <tt><ref id=".P816" name=".P816"></tt> command was given).
434 In 65816 mode, several aliases are accepted, in addition to the official
438 <item><tt>CPA</tt> is an alias for <tt>CMP</tt>
439 <item><tt>DEA</tt> is an alias for <tt>DEC A</tt>
440 <item><tt>INA</tt> is an alias for <tt>INC A</tt>
441 <item><tt>SWA</tt> is an alias for <tt>XBA</tt>
442 <item><tt>TAD</tt> is an alias for <tt>TCD</tt>
443 <item><tt>TAS</tt> is an alias for <tt>TCS</tt>
444 <item><tt>TDA</tt> is an alias for <tt>TDC</tt>
445 <item><tt>TSA</tt> is an alias for <tt>TSC</tt>
449 <sect1>6502X mode<label id="6502X-mode"><p>
451 6502X mode is an extension to the normal 6502 mode. In this mode, several
452 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
453 these instructions are illegal, there are no official mnemonics for them. The
454 unofficial ones are taken from <url
455 url="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
456 ones marked as "stable" are supported. The following table uses information
457 from the mentioned web page, for more information, see there.
460 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
461 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
462 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
463 <item><tt>AXS: X:=A and X-#{imm};</tt>
464 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
465 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
466 <item><tt>LAS: A,X,S:={adr} and S;</tt>
467 <item><tt>LAX: A,X:={adr};</tt>
468 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
469 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
470 <item><tt>SAX: {adr}:=A and X;</tt>
471 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
472 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
478 The 4510 is a microcontroller that is the core of the Commodore C65 aka C64DX.
479 It contains among other functions a slightly modified 65CE02/4502 CPU, to allow
480 address mapping for 20 bits of address space (1 megabyte addressable area).
481 As compared to the description of the CPU in the
482 <url url="http://www.zimmers.net/anonftp/pub/cbm/c65/c65manualupdated.txt.gz"
483 name="C65 System Specification">
484 <url url="https://raw.githubusercontent.com/MEGA65/c65-specifications/master/c65manualupdated.txt"
485 name="(updated version)"> uses these changes:
487 <item><tt>LDA (d,SP),Y</tt> may also be written as <tt>LDA (d,S),Y</tt>
488 (matching the 65816 notataion).
489 <item>All branch instruction allow now 16 bit offsets. To use a 16 bit
490 branch you have to prefix these with an "L" (e.g. "<tt>LBNE</tt>" instead of
491 "<tt>BNE</tt>"). This might change at a later implementation of the assembler.
493 For more information about the Commodore C65/C64DX and the 4510 CPU, see
494 <url url="http://www.zimmers.net/anonftp/pub/cbm/c65/"> and
495 <url url="https://en.wikipedia.org/wiki/Commodore_65" name="Wikipedia">.
498 <sect1>sweet16 mode<label id="sweet16-mode"><p>
500 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
501 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
502 generate code for this pseudo CPU when switched into sweet16 mode. The
503 following is special in sweet16 mode:
507 <item>The '@' character denotes indirect addressing and is no longer available
508 for cheap local labels. If you need cheap local labels, you will have to
509 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
510 name=".LOCALCHAR">/ command.
512 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
513 these identifiers are reserved words.
517 Please note that the assembler does neither supply the interpreter needed for
518 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
519 nor does it call the interpreter. All this must be done by your program. Apple
520 ][ programmers do probably know how to use sweet16 mode.
522 For more information about SWEET 16, see
523 <url url="http://www.6502.org/source/interpreters/sweet16.htm">.
526 <sect1>Number format<p>
528 For literal values, the assembler accepts the widely used number formats: A
529 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
530 denotes a binary value, and a bare number is interpreted as a decimal. There
531 are currently no octal values and no floats.
534 <sect1>Conditional assembly<p>
536 Please note that when using the conditional directives (<tt/.IF/ and friends),
537 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
538 that are not assembled. The reason for this behaviour is that the assembler
539 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
540 conversion of the input stream into tokens still takes place. As a consequence
541 conditional assembly directives may <bf/not/ be used to prevent normal text
542 (used as a comment or similar) from being assembled. <p>
548 <sect1>Expression evaluation<p>
550 All expressions are evaluated with (at least) 32 bit precision. An
551 expression may contain constant values and any combination of internal and
552 external symbols. Expressions that cannot be evaluated at assembly time
553 are stored inside the object file for evaluation by the linker.
554 Expressions referencing imported symbols must always be evaluated by the
558 <sect1>Size of an expression result<p>
560 Sometimes, the assembler must know about the size of the value that is the
561 result of an expression. This is usually the case, if a decision has to be
562 made, to generate a zero page or an absolute memory references. In this
563 case, the assembler has to make some assumptions about the result of an
567 <item> If the result of an expression is constant, the actual value is
568 checked to see if it's a byte sized expression or not.
569 <item> If the expression is explicitly casted to a byte sized expression by
570 one of the '>', '<' or '^' operators, it is a byte expression.
571 <item> If this is not the case, and the expression contains a symbol,
572 explicitly declared as zero page symbol (by one of the .importzp or
573 .exportzp instructions), then the whole expression is assumed to be
575 <item> If the expression contains symbols that are not defined, and these
576 symbols are local symbols, the enclosing scopes are searched for a
577 symbol with the same name. If one exists and this symbol is defined,
578 its attributes are used to determine the result size.
579 <item> In all other cases the expression is assumed to be word sized.
582 Note: If the assembler is not able to evaluate the expression at assembly
583 time, the linker will evaluate it and check for range errors as soon as
587 <sect1>Boolean expressions<p>
589 In the context of a boolean expression, any non zero value is evaluated as
590 true, any other value to false. The result of a boolean expression is 1 if
591 it's true, and zero if it's false. There are boolean operators with extreme
592 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
593 operators are shortcut operators. That is, if the result of the expression is
594 already known, after evaluating the left hand side, the right hand side is
598 <sect1>Constant expressions<p>
600 Sometimes an expression must evaluate to a constant without looking at any
601 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
602 that decides if parts of the code are assembled or not. An expression used in
603 the <tt/.IF/ command cannot reference a symbol defined later, because the
604 decision about the <tt/.IF/ must be made at the point when it is read. If the
605 expression used in such a context contains only constant numerical values,
606 there is no problem. When unresolvable symbols are involved it may get harder
607 for the assembler to determine if the expression is actually constant, and it
608 is even possible to create expressions that aren't recognized as constant.
609 Simplifying the expressions will often help.
611 In cases where the result of the expression is not needed immediately, the
612 assembler will delay evaluation until all input is read, at which point all
613 symbols are known. So using arbitrary complex constant expressions is no
614 problem in most cases.
618 <sect1>Available operators<label id="operators"><p>
622 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
623 | Built-in string functions| 0@
625 | Built-in pseudo-variables| 1@
626 | Built-in pseudo-functions| 1@
627 +| Unary positive| 1@
628 -| Unary negative| 1@
630 .BITNOT| Unary bitwise not| 1@
632 .LOBYTE| Unary low-byte operator| 1@
634 .HIBYTE| Unary high-byte operator| 1@
636 .BANKBYTE| Unary bank-byte operator| 1@
638 *| Multiplication| 2@
640 .MOD| Modulo operator| 2@
642 .BITAND| Bitwise and| 2@
644 .BITXOR| Binary bitwise xor| 2@
646 .SHL| Shift-left operator| 2@
648 .SHR| Shift-right operator| 2@
650 +| Binary addition| 3@
651 -| Binary subtraction| 3@
653 .BITOR| Bitwise or| 3@
655 = | Compare operator (equal)| 4@
656 <>| Compare operator (not equal)| 4@
657 <| Compare operator (less)| 4@
658 >| Compare operator (greater)| 4@
659 <=| Compare operator (less or equal)| 4@
660 >=| Compare operator (greater or equal)| 4@
663 .AND| Boolean and| 5@
664 .XOR| Boolean xor| 5@
666 ||<newline>
670 .NOT| Boolean not| 7@<hline>
672 <caption>Available operators, sorted by precedence
675 To force a specific order of evaluation, parentheses may be used, as usual.
679 <sect>Symbols and labels<p>
681 A symbol or label is an identifier that starts with a letter and is followed
682 by letters and digits. Depending on some features enabled (see
683 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
684 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
685 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
686 other characters may be present. Use of identifiers consisting of a single
687 character will not work in all cases, because some of these identifiers are
688 reserved keywords (for example "A" is not a valid identifier for a label,
689 because it is the keyword for the accumulator).
691 The assembler allows you to use symbols instead of naked values to make
692 the source more readable. There are a lot of different ways to define and
693 use symbols and labels, giving a lot of flexibility.
695 <sect1>Numeric constants<p>
697 Numeric constants are defined using the equal sign or the label assignment
698 operator. After doing
704 may use the symbol "two" in every place where a number is expected, and it is
705 evaluated to the value 2 in this context. The label assignment operator is
706 almost identical, but causes the symbol to be marked as a label, so it may be
707 handled differently in a debugger:
713 The right side can of course be an expression:
720 <label id="variables">
721 <sect1>Numeric variables<p>
723 Within macros and other control structures (<tt><ref id=".REPEAT"
724 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
725 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
726 symbol that may get assigned a different value later:
730 lda #four ; Loads 4 into A
732 lda #four ; Loads 3 into A
735 Since the value of the symbol can change later, it must be possible to
736 evaluate it when used (no delayed evaluation as with normal symbols). So the
737 expression used as the value must be constant.
739 Following is an example for a macro that generates a different label each time
740 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
741 and a numeric variable named <tt>lcount</tt>.
744 .lcount .set 0 ; Initialize the counter
747 .ident (.sprintf ("L%04X", lcount)):
748 lcount .set lcount + 1
753 <sect1>Standard labels<p>
755 A label is defined by writing the name of the label at the start of the line
756 (before any instruction mnemonic, macro or pseudo directive), followed by a
757 colon. This will declare a symbol with the given name and the value of the
758 current program counter.
761 <sect1>Local labels and symbols<p>
763 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
764 create regions of code where the names of labels and symbols are local to this
765 region. They are not known outside of this region and cannot be accessed from
766 there. Such regions may be nested like PROCEDUREs in Pascal.
768 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
769 directive for more information.
772 <sect1>Cheap local labels<p>
774 Cheap local labels are defined like standard labels, but the name of the
775 label must begin with a special symbol (usually '@', but this can be
776 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
779 Cheap local labels are visible only between two non cheap labels. As soon as a
780 standard symbol is encountered (this may also be a local symbol if inside a
781 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
782 cheap local symbol goes out of scope.
784 You may use cheap local labels as an easy way to reuse common label
785 names like "Loop". Here is an example:
788 Clear: lda #$00 ; Global label
790 @Loop: sta Mem,y ; Local label
794 Sub: ... ; New global label
795 bne @Loop ; ERROR: Unknown identifier!
798 <sect1>Unnamed labels<p>
800 If you really want to write messy code, there are also unnamed labels. These
801 labels do not have a name (you guessed that already, didn't you?). A colon is
802 used to mark the absence of the name.
804 Unnamed labels may be accessed by using the colon plus several minus or plus
805 characters as a label designator. Using the '-' characters will create a back
806 reference (use the n'th label backwards), using '+' will create a forward
807 reference (use the n'th label in forward direction). An example will help to
830 As you can see from the example, unnamed labels will make even short
831 sections of code hard to understand, because you have to count labels
832 to find branch targets (this is the reason why I for my part do
833 prefer the "cheap" local labels). Nevertheless, unnamed labels are
834 convenient in some situations, so it's your decision.
836 <em/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
837 unnamed ones, so scopes don't have an effect on unnamed labels.
841 <sect1>Using macros to define labels and constants<p>
843 While there are drawbacks with this approach, it may be handy in a few rare
844 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
845 to define symbols or constants that may be used elsewhere. One of the
846 advantages is that you can use it to define string constants (this is not
847 possible with the other symbol types).
849 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
850 so the names do not adhere to scoping, diagnostics may be misleading, there
851 are no symbols to look up in the map file, and there is no debug info.
852 Especially the first problem in the list can lead to very nasty programming
853 errors. Because of these problems, the general advice is, <bf/NOT/ do use
854 <tt/.DEFINE/ if you don't have to.
860 .DEFINE version "SOS V2.3"
862 four = two * two ; Ok
865 .PROC ; Start local scope
866 two = 3 ; Will give "2 = 3" - invalid!
871 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
873 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
874 id="option-g" name="-g"> is given on the command line), global, local and
875 cheap local labels are written to the object file and will be available in the
876 symbol file via the linker. Unnamed labels are not written to the object file,
877 because they don't have a name which would allow to access them.
881 <sect>Scopes<label id="scopes"><p>
883 ca65 implements several sorts of scopes for symbols.
885 <sect1>Global scope<p>
887 All (non cheap local) symbols that are declared outside of any nested scopes
891 <sect1>Cheap locals<p>
893 A special scope is the scope for cheap local symbols. It lasts from one non
894 local symbol to the next one, without any provisions made by the programmer.
895 All other scopes differ in usage but use the same concept internally.
898 <sect1>Generic nested scopes<p>
900 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
901 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
902 The scope can have a name, in which case it is accessible from the outside by
903 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
904 have a name, all symbols created within the scope are local to the scope, and
905 aren't accessible from the outside.
907 A nested scope can access symbols from the local or from enclosing scopes by
908 name without using explicit scope names. In some cases there may be
909 ambiguities, for example if there is a reference to a local symbol that is not
910 yet defined, but a symbol with the same name exists in outer scopes:
922 In the example above, the <tt/lda/ instruction will load the value 3 into the
923 accumulator, because <tt/foo/ is redefined in the scope. However:
935 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
936 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
937 absolute mode is used instead. In fact, the assembler will not use absolute
938 mode by default, but it will search through the enclosing scopes for a symbol
939 with the given name. If one is found, the address size of this symbol is used.
940 This may lead to errors:
952 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
953 instruction, it will search for an already defined symbol <tt/foo/. It will
954 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
955 zeropage symbol. So the assembler will use zeropage addressing mode. If
956 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
957 the address in the <tt/lda/ instruction already translated, but since the new
958 value needs absolute addressing mode, this fails, and an error message "Range
961 Of course the most simple solution for the problem is to move the definition
962 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
963 rare cases when this cannot be done. In these cases, you can use one of the
964 address size override operators:
976 This will cause the <tt/lda/ instruction to be translated using absolute
977 addressing mode, which means changing the symbol reference later does not
981 <sect1>Nested procedures<p>
983 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
984 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
985 name, and a it will introduce a symbol with this name in the enclosing scope.
994 is actually the same as
1003 This is the reason why a procedure must have a name. If you want a scope
1004 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
1006 <em/Note:/ As you can see from the example above, scopes and symbols live in
1007 different namespaces. There can be a symbol named <tt/foo/ and a scope named
1008 <tt/foo/ without any conflicts (but see the section titled <ref
1009 id="scopesearch" name=""Scope search order"">).
1012 <sect1>Structs, unions and enums<p>
1014 Structs, unions and enums are explained in a <ref id="structs" name="separate
1015 section">, I do only cover them here, because if they are declared with a
1016 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
1017 name=".SCOPE">/. However, when no name is specified, the behaviour is
1018 different: In this case, no new scope will be opened, symbols declared within
1019 a struct, union, or enum declaration will then be added to the enclosing scope
1023 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1025 Accessing symbols from other scopes is possible by using an explicit scope
1026 specification, provided that the scope where the symbol lives in has a name.
1027 The namespace token (<tt/::/) is used to access other scopes:
1035 lda foo::bar ; Access foo in scope bar
1038 The only way to deny access to a scope from the outside is to declare a scope
1039 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1041 A special syntax is used to specify the global scope: If a symbol or scope is
1042 preceded by the namespace token, the global scope is searched:
1049 lda #::bar ; Access the global bar (which is 3)
1054 <sect1>Scope search order<label id="scopesearch"><p>
1056 The assembler searches for a scope in a similar way as for a symbol. First, it
1057 looks in the current scope, and then it walks up the enclosing scopes until
1060 However, one important thing to note when using explicit scope syntax is, that
1061 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1062 used without a preceding definition. This means that in the following
1071 lda #foo::bar ; Will load 3, not 2!
1078 the reference to the scope <tt/foo/ will use the global scope, and not the
1079 local one, because the local one is not visible at the point where it is
1082 Things get more complex if a complete chain of scopes is specified:
1093 lda #outer::inner::bar ; 1
1105 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1106 assembler will first search in the local scope for a scope named <tt/outer/.
1107 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1108 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1109 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1110 this scope, the assembler looks for a symbol named <tt/bar/.
1112 Please note that once the anchor scope is found, all following scopes
1113 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1114 assembler will search the scope tree only for the first scope (if it is not
1115 anchored in the root scope). Starting from there on, there is no flexibility,
1116 so if the scope named <tt/outer/ found by the assembler does not contain a
1117 scope named <tt/inner/, this would be an error, even if such a pair does exist
1118 (one level up in global scope).
1120 Ambiguities that may be introduced by this search algorithm may be removed by
1121 anchoring the scope specification in the global scope. In the example above,
1122 if you want to access the "other" symbol <tt/bar/, you would have to write:
1133 lda #::outer::inner::bar ; 2
1146 <sect>Address sizes and memory models<label id="address-sizes"><p>
1148 <sect1>Address sizes<p>
1150 ca65 assigns each segment and each symbol an address size. This is true, even
1151 if the symbol is not used as an address. You may also think of a value range
1152 of the symbol instead of an address size.
1154 Possible address sizes are:
1157 <item>Zeropage or direct (8 bits)
1158 <item>Absolute (16 bits)
1160 <item>Long (32 bits)
1163 Since the assembler uses default address sizes for the segments and symbols,
1164 it is usually not necessary to override the default behaviour. In cases, where
1165 it is necessary, the following keywords may be used to specify address sizes:
1168 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1169 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1170 <item>FAR for far addressing (24 bits).
1171 <item>LONG or DWORD for long addressing (32 bits).
1175 <sect1>Address sizes of segments<p>
1177 The assembler assigns an address size to each segment. Since the
1178 representation of a label within this segment is "segment start + offset",
1179 labels will inherit the address size of the segment they are declared in.
1181 The address size of a segment may be changed, by using an optional address
1182 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1183 an explanation on how this is done.
1186 <sect1>Address sizes of symbols<p>
1191 <sect1>Memory models<p>
1193 The default address size of a segment depends on the memory model used. Since
1194 labels inherit the address size from the segment they are declared in,
1195 changing the memory model is an easy way to change the address size of many
1201 <sect>Pseudo variables<label id="pseudo-variables"><p>
1203 Pseudo variables are readable in all cases, and in some special cases also
1206 <sect1><tt>*</tt><p>
1208 Reading this pseudo variable will return the program counter at the start
1209 of the current input line.
1211 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1212 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1213 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1216 <sect1><tt>.ASIZE</tt><label id=".ASIZE"><p>
1218 Reading this pseudo variable will return the current size of the
1219 Accumulator in bits.
1221 For the 65816 instruction set .ASIZE will return either 8 or 16, depending
1222 on the current size of the operand in immediate accu addressing mode.
1224 For all other CPU instruction sets, .ASIZE will always return 8.
1229 ; Reverse Subtract with Accumulator
1242 See also: <tt><ref id=".ISIZE" name=".ISIZE"></tt>
1245 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1247 Reading this pseudo variable will give a constant integer value that
1248 tells which CPU is currently enabled. It can also tell which instruction
1249 set the CPU is able to translate. The value read from the pseudo variable
1250 should be further examined by using one of the constants defined by the
1251 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1253 It may be used to replace the .IFPxx pseudo instructions or to construct
1254 even more complex expressions.
1260 .if (.cpu .bitand CPU_ISET_65816)
1272 <sect1><tt>.ISIZE</tt><label id=".ISIZE"><p>
1274 Reading this pseudo variable will return the current size of the Index
1277 For the 65816 instruction set .ISIZE will return either 8 or 16, depending
1278 on the current size of the operand in immediate index addressing mode.
1280 For all other CPU instruction sets, .ISIZE will always return 8.
1282 See also: <tt><ref id=".ASIZE" name=".ASIZE"></tt>
1285 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1287 This builtin pseudo variable is only available in macros. It is replaced by
1288 the actual number of parameters that were given in the macro invocation.
1293 .macro foo arg1, arg2, arg3
1294 .if .paramcount <> 3
1295 .error "Too few parameters for macro foo"
1301 See section <ref id="macros" name="Macros">.
1304 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1306 Reading this pseudo variable will give a constant integer value that
1307 represents the current time in POSIX standard (as seconds since the
1310 It may be used to encode the time of translation somewhere in the created
1316 .dword .time ; Place time here
1320 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1322 Reading this pseudo variable will give the assembler version according to
1323 the following formula:
1325 VER_MAJOR*$100 + VER_MINOR*$10
1327 It may be used to encode the assembler version or check the assembler for
1328 special features not available with older versions.
1332 Version 2.14 of the assembler will return $2E0 as numerical constant when
1333 reading the pseudo variable <tt/.VERSION/.
1337 <sect>Pseudo functions<label id="pseudo-functions"><p>
1339 Pseudo functions expect their arguments in parenthesis, and they have a result,
1340 either a string or an expression.
1343 <sect1><tt>.ADDRSIZE</tt><label id=".ADDRSIZE"><p>
1345 The <tt/.ADDRSIZE/ function is used to return the interal address size
1346 associated with a symbol. This can be helpful in macros when knowing the address
1347 size of symbol can help with custom instructions.
1353 .if .ADDRSIZE(foo) = 1
1354 ;do custom command based on zeropage addressing:
1356 .elseif .ADDRSIZE(foo) = 2
1357 ;do custom command based on absolute addressing:
1360 .elseif .ADDRSIZE(foo) = 0
1361 ; no address size defined for this symbol:
1362 .out .sprintf("Error, address size unknown for symbol %s", .string(foo))
1367 This command is new and must be enabled with the <tt/.FEATURE addrsize/ command.
1369 See: <tt><ref id=".FEATURE" name=".FEATURE"></tt>
1372 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1374 The <tt/.BANK/ function is used to support systems with banked memory. The
1375 argument is an expression with exactly one segment reference - usually a
1376 label. The function result is the value of the <tt/bank/ attribute assigned
1377 to the run memory area of the segment. Please see the linker documentation
1378 for more information about memory areas and their attributes.
1380 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1381 containing specific data is available.
1383 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1384 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1385 name=".LOBYTE"></tt> or similar functions to address just part of it.
1387 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1388 an expression containing <tt/.BANK/ can never be used where a constant known
1389 result is expected (for example with <tt/.RES/).
1406 .byte <.BANK (banked_func_1)
1409 .byte <.BANK (banked_func_2)
1415 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1417 The function returns the bank byte (that is, bits 16-23) of its argument.
1418 It works identical to the '^' operator.
1420 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1421 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1424 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1426 Builtin function. The function evaluates its argument in braces and yields
1427 "false" if the argument is non blank (there is an argument), and "true" if
1428 there is no argument. The token list that makes up the function argument
1429 may optionally be enclosed in curly braces. This allows the inclusion of
1430 tokens that would otherwise terminate the list (the closing right
1431 parenthesis). The curly braces are not considered part of the list, a list
1432 just consisting of curly braces is considered to be empty.
1434 As an example, the <tt/.IFBLANK/ statement may be replaced by
1442 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1444 Builtin string function. The function allows to concatenate a list of string
1445 constants separated by commas. The result is a string constant that is the
1446 concatenation of all arguments. This function is most useful in macros and
1447 when used together with the <tt/.STRING/ builtin function. The function may
1448 be used in any case where a string constant is expected.
1453 .include .concat ("myheader", ".", "inc")
1456 This is the same as the command
1459 .include "myheader.inc"
1463 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1465 Builtin function. The function evaluates its argument in braces and
1466 yields "true" if the argument is a constant expression (that is, an
1467 expression that yields a constant value at assembly time) and "false"
1468 otherwise. As an example, the .IFCONST statement may be replaced by
1475 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1477 The function returns the high byte (that is, bits 8-15) of its argument.
1478 It works identical to the '>' operator.
1480 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1481 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1484 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1486 The function returns the high word (that is, bits 16-31) of its argument.
1488 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1491 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1493 The function expects a string as its argument, and converts this argument
1494 into an identifier. If the string starts with the current <tt/<ref
1495 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1496 identifier, otherwise it will be converted into a normal identifier.
1501 .macro makelabel arg1, arg2
1502 .ident (.concat (arg1, arg2)):
1505 makelabel "foo", "bar"
1507 .word foobar ; Valid label
1511 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1513 Builtin function. Extracts the left part of a given token list.
1518 .LEFT (<int expr>, <token list>)
1521 The first integer expression gives the number of tokens to extract from
1522 the token list. The second argument is the token list itself. The token
1523 list may optionally be enclosed into curly braces. This allows the
1524 inclusion of tokens that would otherwise terminate the list (the closing
1525 right paren in the given case).
1529 To check in a macro if the given argument has a '#' as first token
1530 (immediate addressing mode), use something like this:
1535 .if (.match (.left (1, {arg}), #))
1537 ; ldax called with immediate operand
1545 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1546 name=".RIGHT"></tt> builtin functions.
1549 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1551 The function returns the low byte (that is, bits 0-7) of its argument.
1552 It works identical to the '<' operator.
1554 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1555 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1558 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1560 The function returns the low word (that is, bits 0-15) of its argument.
1562 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1565 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1567 Builtin function. Matches two token lists against each other. This is
1568 most useful within macros, since macros are not stored as strings, but
1574 .MATCH(<token list #1>, <token list #2>)
1577 Both token list may contain arbitrary tokens with the exception of the
1578 terminator token (comma resp. right parenthesis) and
1585 The token lists may optionally be enclosed into curly braces. This allows
1586 the inclusion of tokens that would otherwise terminate the list (the closing
1587 right paren in the given case). Often a macro parameter is used for any of
1590 Please note that the function does only compare tokens, not token
1591 attributes. So any number is equal to any other number, regardless of the
1592 actual value. The same is true for strings. If you need to compare tokens
1593 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1594 name=".XMATCH"></tt> function.
1598 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1599 while honoring the sign bit. The builtin processor instructions will allow
1600 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1601 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1602 to check for this and print and error for invalid calls.
1607 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1608 .error "Syntax error"
1611 cmp #$80 ; Bit 7 into carry
1612 lsr a ; Shift carry into bit 7
1617 The macro will only accept no arguments, or one argument that must be the
1618 reserved keyword "A".
1620 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1623 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1625 Builtin function. The result is the larger of two values.
1630 .MAX (<value #1>, <value #2>)
1636 ; Reserve space for the larger of two data blocks
1637 savearea: .max (.sizeof (foo), .sizeof (bar))
1640 See: <tt><ref id=".MIN" name=".MIN"></tt>
1643 <sect1><tt>.MID</tt><label id=".MID"><p>
1645 Builtin function. Takes a starting index, a count and a token list as
1646 arguments. Will return part of the token list.
1651 .MID (<int expr>, <int expr>, <token list>)
1654 The first integer expression gives the starting token in the list (the first
1655 token has index 0). The second integer expression gives the number of tokens
1656 to extract from the token list. The third argument is the token list itself.
1657 The token list may optionally be enclosed into curly braces. This allows the
1658 inclusion of tokens that would otherwise terminate the list (the closing
1659 right paren in the given case).
1663 To check in a macro if the given argument has a '<tt/#/' as first token
1664 (immediate addressing mode), use something like this:
1669 .if (.match (.mid (0, 1, {arg}), #))
1671 ; ldax called with immediate operand
1679 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1680 name=".RIGHT"></tt> builtin functions.
1683 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1685 Builtin function. The result is the smaller of two values.
1690 .MIN (<value #1>, <value #2>)
1696 ; Reserve space for some data, but 256 bytes minimum
1697 savearea: .min (.sizeof (foo), 256)
1700 See: <tt><ref id=".MAX" name=".MAX"></tt>
1703 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1705 Builtin function. The function expects an identifier as argument in braces.
1706 The argument is evaluated, and the function yields "true" if the identifier
1707 is a symbol that has already been referenced somewhere in the source file up
1708 to the current position. Otherwise the function yields false. As an example,
1709 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1715 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1718 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1720 Builtin function. Extracts the right part of a given token list.
1725 .RIGHT (<int expr>, <token list>)
1728 The first integer expression gives the number of tokens to extract from the
1729 token list. The second argument is the token list itself. The token list
1730 may optionally be enclosed into curly braces. This allows the inclusion of
1731 tokens that would otherwise terminate the list (the closing right paren in
1734 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1735 name=".MID"></tt> builtin functions.
1738 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1740 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1741 argument can be a struct/union, a struct member, a procedure, or a label. In
1742 case of a procedure or label, its size is defined by the amount of data
1743 placed in the segment where the label is relative to. If a line of code
1744 switches segments (for example in a macro) data placed in other segments
1745 does not count for the size.
1747 Please note that a symbol or scope must exist, before it is used together with
1748 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1749 A scope has preference over a symbol with the same name, so if the last part
1750 of a name represents both, a scope and a symbol, the scope is chosen over the
1753 After the following code:
1756 .struct Point ; Struct size = 4
1761 P: .tag Point ; Declare a point
1762 @P: .tag Point ; Declare another point
1774 .data ; Segment switch!!!
1780 <tag><tt/.sizeof(Point)/</tag>
1781 will have the value 4, because this is the size of struct <tt/Point/.
1783 <tag><tt/.sizeof(Point::xcoord)/</tag>
1784 will have the value 2, because this is the size of the member <tt/xcoord/
1785 in struct <tt/Point/.
1787 <tag><tt/.sizeof(P)/</tag>
1788 will have the value 4, this is the size of the data declared on the same
1789 source line as the label <tt/P/, which is in the same segment that <tt/P/
1792 <tag><tt/.sizeof(@P)/</tag>
1793 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1794 does also work for cheap local symbols.
1796 <tag><tt/.sizeof(Code)/</tag>
1797 will have the value 3, since this is amount of data emitted into the code
1798 segment, the segment that was active when <tt/Code/ was entered. Note that
1799 this value includes the amount of data emitted in child scopes (in this
1800 case <tt/Code::Inner/).
1802 <tag><tt/.sizeof(Code::Inner)/</tag>
1803 will have the value 1 as expected.
1805 <tag><tt/.sizeof(Data)/</tag>
1806 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1807 the segment is switched after entry, this data is emitted into another
1812 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1814 Builtin function. The function accepts a string and an index as
1815 arguments and returns the value of the character at the given position
1816 as an integer value. The index is zero based.
1822 ; Check if the argument string starts with '#'
1823 .if (.strat (Arg, 0) = '#')
1830 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1832 Builtin function. It expects a format string as first argument. The number
1833 and type of the following arguments depend on the format string. The format
1834 string is similar to the one of the C <tt/printf/ function. Missing things
1835 are: Length modifiers, variable width.
1837 The result of the function is a string.
1844 ; Generate an identifier:
1845 .ident (.sprintf ("%s%03d", "label", num)):
1849 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1851 Builtin function. The function accepts an argument in braces and converts
1852 this argument into a string constant. The argument may be an identifier, or
1853 a constant numeric value.
1855 Since you can use a string in the first place, the use of the function may
1856 not be obvious. However, it is useful in macros, or more complex setups.
1861 ; Emulate other assemblers:
1863 .segment .string(name)
1868 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1870 Builtin function. The function accepts a string argument in braces and
1871 evaluates to the length of the string.
1875 The following macro encodes a string as a pascal style string with
1876 a leading length byte.
1880 .byte .strlen(Arg), Arg
1885 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1887 Builtin function. The function accepts a token list in braces. The function
1888 result is the number of tokens given as argument. The token list may
1889 optionally be enclosed into curly braces which are not considered part of
1890 the list and not counted. Enclosement in curly braces allows the inclusion
1891 of tokens that would otherwise terminate the list (the closing right paren
1896 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1897 with the normal 6502 instructions). To translate it into two separate 8 bit
1898 load instructions, the '#' token has to get stripped from the argument:
1902 .if (.match (.mid (0, 1, {arg}), #))
1903 ; ldax called with immediate operand
1904 lda #<(.right (.tcount ({arg})-1, {arg}))
1905 ldx #>(.right (.tcount ({arg})-1, {arg}))
1913 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1915 Builtin function. Matches two token lists against each other. This is
1916 most useful within macros, since macros are not stored as strings, but
1922 .XMATCH(<token list #1>, <token list #2>)
1925 Both token list may contain arbitrary tokens with the exception of the
1926 terminator token (comma resp. right parenthesis) and
1933 The token lists may optionally be enclosed into curly braces. This allows
1934 the inclusion of tokens that would otherwise terminate the list (the closing
1935 right paren in the given case). Often a macro parameter is used for any of
1938 The function compares tokens <em/and/ token values. If you need a function
1939 that just compares the type of tokens, have a look at the <tt><ref
1940 id=".MATCH" name=".MATCH"></tt> function.
1942 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1946 <sect>Control commands<label id="control-commands"><p>
1948 Here's a list of all control commands and a description, what they do:
1951 <sect1><tt>.A16</tt><label id=".A16"><p>
1953 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1955 Note: This command will not emit any code, it will tell the assembler to
1956 create 16 bit operands for immediate accumulator addressing mode.
1958 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1961 <sect1><tt>.A8</tt><label id=".A8"><p>
1963 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1965 Note: This command will not emit any code, it will tell the assembler to
1966 create 8 bit operands for immediate accu addressing mode.
1968 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1971 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1973 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1974 may be used for better readability if the data words are address values. In
1975 65816 mode, the address is forced to be 16 bit wide to fit into the current
1976 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1977 must be followed by a sequence of (not necessarily constant) expressions.
1982 .addr $0D00, $AF13, _Clear
1985 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1989 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1991 Align data to a given boundary. The command expects a constant integer
1992 argument in the range 1 ... 65536, plus an optional second argument
1993 in byte range. If there is a second argument, it is used as fill value,
1994 otherwise the value defined in the linker configuration file is used
1995 (the default for this value is zero).
1997 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1998 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1999 number of bytes, since that would break address calculations within the
2000 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
2001 of the alignment, because that allows the number of fill bytes to be
2002 calculated in advance by the assembler. You are therefore required to
2003 specify a matching alignment for the segment in the linker config. The
2004 linker will output a warning if the alignment of the segment is less than
2005 what is necessary to have a correct alignment in the object file.
2013 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
2014 commands with different arguments. To allow the assembler to calculate the
2015 number of fill bytes in advance, the alignment of the segment must be a
2016 multiple of each of the alignment factors. This may result in unexpectedly
2017 large alignments for the segment within the module.
2028 For the assembler to be able to align correctly, the segment must be aligned
2029 to the least common multiple of 15 and 18 which is 90. The assembler will
2030 calculate this automatically and will mark the segment with this value.
2032 Unfortunately, the combined alignment may get rather large without the user
2033 knowing about it, wasting space in the final executable. If we add another
2034 alignment to the example above
2045 the assembler will force a segment alignment to the least common multiple of
2046 15, 18 and 251 - which is 22590. To protect the user against errors, the
2047 assembler will issue a warning when the combined alignment exceeds 256. The
2048 command line option <tt><ref id="option--large-alignment"
2049 name="--large-alignment"></tt> will disable this warning.
2051 Please note that with alignments that are a power of two (which were the
2052 only alignments possible in older versions of the assembler), the problem is
2053 less severe, because the least common multiple of powers to the same base is
2054 always the larger one.
2058 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
2060 Define a string with a trailing zero.
2065 Msg: .asciiz "Hello world"
2068 This will put the string "Hello world" followed by a binary zero into
2069 the current segment. There may be more strings separated by commas, but
2070 the binary zero is only appended once (after the last one).
2073 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2075 Add an assertion. The command is followed by an expression, an action
2076 specifier, and an optional message that is output in case the assertion
2077 fails. If no message was given, the string "Assertion failed" is used. The
2078 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2079 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2080 assembler if possible, and in any case, it's also passed to the linker in
2081 the object file (if one is generated). The linker will then evaluate the
2082 expression when segment placement has been done.
2087 .assert * = $8000, error, "Code not at $8000"
2090 The example assertion will check that the current location is at $8000,
2091 when the output file is written, and abort with an error if this is not
2092 the case. More complex expressions are possible. The action specifier
2093 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2094 an error message. In the latter case, generation of the output file is
2095 suppressed in both the assembler and linker.
2098 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2100 Is followed by a plus or a minus character. When switched on (using a
2101 +), undefined symbols are automatically marked as import instead of
2102 giving errors. When switched off (which is the default so this does not
2103 make much sense), this does not happen and an error message is
2104 displayed. The state of the autoimport flag is evaluated when the
2105 complete source was translated, before outputting actual code, so it is
2106 <em/not/ possible to switch this feature on or off for separate sections
2107 of code. The last setting is used for all symbols.
2109 You should probably not use this switch because it delays error
2110 messages about undefined symbols until the link stage. The cc65
2111 compiler (which is supposed to produce correct assembler code in all
2112 circumstances, something which is not true for most assembler
2113 programmers) will insert this command to avoid importing each and every
2114 routine from the runtime library.
2119 .autoimport + ; Switch on auto import
2122 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2124 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2125 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2126 the operator '^' prepended to each expression in its list.
2131 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2133 TableLookupLo: .lobytes MyTable
2134 TableLookupHi: .hibytes MyTable
2135 TableLookupBank: .bankbytes MyTable
2138 which is equivalent to
2141 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2142 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2143 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2146 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2147 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2148 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2151 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2153 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2154 so this is a shortcut for
2160 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2163 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2165 Define byte sized data. Must be followed by a sequence of (byte ranged)
2166 expressions or strings.
2172 .byt "world", $0D, $00
2176 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2178 Switch on or off case sensitivity on identifiers. The default is off
2179 (that is, identifiers are case sensitive), but may be changed by the
2180 -i switch on the command line.
2181 The command must be followed by a '+' or '-' character to switch the
2182 option on or off respectively.
2187 .case - ; Identifiers are not case sensitive
2191 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2193 Apply a custom mapping for characters. The command is followed by two
2194 numbers. The first one is the index of the source character (range 0..255);
2195 the second one is the mapping (range 0..255). The mapping applies to all
2196 character and string constants <em/when/ they generate output; and, overrides
2197 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2198 command line switch.
2202 .charmap $41, $61 ; Map 'A' to 'a'
2206 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2208 Switch to the CODE segment. The name of the CODE segment is always
2209 "CODE", so this is a shortcut for
2215 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2218 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2220 Export a symbol and mark it in a special way. The linker is able to build
2221 tables of all such symbols. This may be used to automatically create a list
2222 of functions needed to initialize linked library modules.
2224 Note: The linker has a feature to build a table of marked routines, but it
2225 is your code that must call these routines, so just declaring a symbol with
2226 <tt/.CONDES/ does nothing by itself.
2228 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2229 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2230 is implied by <tt/.CONDES/.
2232 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2233 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2234 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2235 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2236 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2237 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2238 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2240 After the type, an optional priority may be specified. Higher numeric values
2241 mean higher priority. If no priority is given, the default priority of 7 is
2242 used. Be careful when assigning priorities to your own module constructors
2243 so they won't interfere with the ones in the cc65 library.
2248 .condes ModuleInit, constructor
2249 .condes ModInit, 0, 16
2252 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2253 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2254 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2255 name="Module constructors/destructors"> explaining the feature in more
2259 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2261 Export a symbol and mark it as a module constructor. This may be used
2262 together with the linker to build a table of constructor subroutines that
2263 are called by the startup code.
2265 Note: The linker has a feature to build a table of marked routines, but it
2266 is your code that must call these routines, so just declaring a symbol as
2267 constructor does nothing by itself.
2269 A constructor is always exported as an absolute (16 bit) symbol. You don't
2270 need to use an additional <tt/.export/ statement, this is implied by
2271 <tt/.constructor/. It may have an optional priority that is separated by a
2272 comma. Higher numeric values mean a higher priority. If no priority is
2273 given, the default priority of 7 is used. Be careful when assigning
2274 priorities to your own module constructors so they won't interfere with the
2275 ones in the cc65 library.
2280 .constructor ModuleInit
2281 .constructor ModInit, 16
2284 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2285 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2286 <ref id="condes" name="Module constructors/destructors"> explaining the
2287 feature in more detail.
2290 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2292 Switch to the DATA segment. The name of the DATA segment is always
2293 "DATA", so this is a shortcut for
2299 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2302 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2304 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2305 create word sized data in native 65XX format). Must be followed by a
2306 sequence of (word ranged) expressions.
2314 This will emit the bytes
2320 into the current segment in that order.
2323 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2325 Switch on or off debug info generation. The default is off (that is,
2326 the object file will not contain debug infos), but may be changed by the
2327 -g switch on the command line.
2328 The command must be followed by a '+' or '-' character to switch the
2329 option on or off respectively.
2334 .debuginfo + ; Generate debug info
2338 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2340 Start a define style macro definition. The command is followed by an
2341 identifier (the macro name) and optionally by a list of formal arguments
2344 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2345 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2348 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2349 section <ref id="macros" name="Macros">.
2352 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2354 Delete a classic macro (defined with <tt><ref id=".MACRO"
2355 name=".MACRO"></tt>) . The command is followed by the name of an
2356 existing macro. Its definition will be deleted together with the name.
2357 If necessary, another macro with this name may be defined later.
2359 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2360 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2361 <tt><ref id=".MACRO" name=".MACRO"></tt>
2363 See also section <ref id="macros" name="Macros">.
2366 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2368 Builtin function. The function expects an identifier as argument in braces.
2369 The argument is evaluated, and the function yields "true" if the identifier
2370 is a symbol that is already defined somewhere in the source file up to the
2371 current position. Otherwise the function yields false. As an example, the
2372 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2379 <sect1><tt>.DEFINEDMACRO</tt><label id=".DEFINEDMACRO"><p>
2381 Builtin function. The function expects an identifier as argument in braces.
2382 The argument is evaluated, and the function yields "true" if the identifier
2383 has already been defined as the name of a macro. Otherwise the function yields
2392 .if .definedmacro(add)
2401 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2403 Export a symbol and mark it as a module destructor. This may be used
2404 together with the linker to build a table of destructor subroutines that
2405 are called by the startup code.
2407 Note: The linker has a feature to build a table of marked routines, but it
2408 is your code that must call these routines, so just declaring a symbol as
2409 constructor does nothing by itself.
2411 A destructor is always exported as an absolute (16 bit) symbol. You don't
2412 need to use an additional <tt/.export/ statement, this is implied by
2413 <tt/.destructor/. It may have an optional priority that is separated by a
2414 comma. Higher numerical values mean a higher priority. If no priority is
2415 given, the default priority of 7 is used. Be careful when assigning
2416 priorities to your own module destructors so they won't interfere with the
2417 ones in the cc65 library.
2422 .destructor ModuleDone
2423 .destructor ModDone, 16
2426 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2427 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2428 section <ref id="condes" name="Module constructors/destructors"> explaining
2429 the feature in more detail.
2432 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2434 Define dword sized data (4 bytes) Must be followed by a sequence of
2440 .dword $12344512, $12FA489
2444 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2446 Conditional assembly: Reverse the current condition.
2449 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2451 Conditional assembly: Reverse current condition and test a new one.
2454 <sect1><tt>.END</tt><label id=".END"><p>
2456 Forced end of assembly. Assembly stops at this point, even if the command
2457 is read from an include file.
2460 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2462 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2465 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2467 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2468 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2471 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2473 Marks the end of a macro definition.
2475 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2476 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2477 <tt><ref id=".MACRO" name=".MACRO"></tt>
2479 See also section <ref id="macros" name="Macros">.
2482 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2484 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2487 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2489 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2492 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2494 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2497 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2499 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2500 command and the separate section named <ref id="structs" name=""Structs
2504 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2506 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2507 command and the separate section named <ref id="structs" name=""Structs
2511 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2513 Start an enumeration. This directive is very similar to the C <tt/enum/
2514 keyword. If a name is given, a new scope is created for the enumeration,
2515 otherwise the enumeration members are placed in the enclosing scope.
2517 In the enumeration body, symbols are declared. The first symbol has a value
2518 of zero, and each following symbol will get the value of the preceding plus
2519 one. This behaviour may be overridden by an explicit assignment. Two symbols
2520 may have the same value.
2532 Above example will create a new scope named <tt/errorcodes/ with three
2533 symbols in it that get the values 0, 1 and 2 respectively. Another way
2534 to write this would have been:
2544 Please note that explicit scoping must be used to access the identifiers:
2547 .word errorcodes::no_error
2550 A more complex example:
2559 EWOULDBLOCK = EAGAIN
2563 In this example, the enumeration does not have a name, which means that the
2564 members will be visible in the enclosing scope and can be used in this scope
2565 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2566 The value for the following members is incremented by one, so <tt/EOK/ would
2567 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2568 override for the value using an already defined symbol.
2571 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2573 Force an assembly error. The assembler will output an error message
2574 preceded by "User error". Assembly is continued but no object file will
2577 This command may be used to check for initial conditions that must be
2578 set before assembling a source file.
2588 .error "Must define foo or bar!"
2592 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2593 <tt><ref id=".OUT" name=".OUT"></tt>,
2594 <tt><ref id=".WARNING" name=".WARNING"></tt>
2597 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2599 Abort a macro expansion immediately. This command is often useful in
2602 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2603 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2604 <tt><ref id=".MACRO" name=".MACRO"></tt>
2606 See also section <ref id="macros" name="Macros">.
2609 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2611 Make symbols accessible from other modules. Must be followed by a comma
2612 separated list of symbols to export, with each one optionally followed by an
2613 address specification and (also optional) an assignment. Using an additional
2614 assignment in the export statement allows to define and export a symbol in
2615 one statement. The default is to export the symbol with the address size it
2616 actually has. The assembler will issue a warning, if the symbol is exported
2617 with an address size smaller than the actual address size.
2624 .export foobar: far = foo * bar
2625 .export baz := foobar, zap: far = baz - bar
2628 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2631 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2634 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2636 Make symbols accessible from other modules. Must be followed by a comma
2637 separated list of symbols to export. The exported symbols are explicitly
2638 marked as zero page symbols. An assignment may be included in the
2639 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2646 .exportzp baz := $02
2649 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2652 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2654 Define far (24 bit) address data. The command must be followed by a
2655 sequence of (not necessarily constant) expressions.
2660 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2663 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2666 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2668 Force an assembly error and terminate assembly. The assembler will output an
2669 error message preceded by "User error" and will terminate assembly
2672 This command may be used to check for initial conditions that must be
2673 set before assembling a source file.
2683 .fatal "Must define foo or bar!"
2687 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2688 <tt><ref id=".OUT" name=".OUT"></tt>,
2689 <tt><ref id=".WARNING" name=".WARNING"></tt>
2692 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2694 This directive may be used to enable one or more compatibility features
2695 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2696 possible, it may be useful when porting sources written for other
2697 assemblers. There is no way to switch a feature off, once you have
2698 enabled it, so using
2704 will enable the feature until end of assembly is reached.
2706 The following features are available:
2710 <tag><tt>addrsize</tt><label id="addrsize"></tag>
2712 Enables the .ADDRSIZE pseudo function. This function is experimental and not enabled by default.
2714 See also: <tt><ref id=".ADDRSIZE" name=".ADDRSIZE"></tt>
2716 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2718 Accept the at character (`@') as a valid character in identifiers. The
2719 at character is not allowed to start an identifier, even with this
2722 <tag><tt>bracket_as_indirect</tt><label id="bracket_as_indirect"></tag>
2724 Use <tt>[]</tt> instead of <tt>()</tt> for the indirect addressing modes.
2734 <em/Note:/ This should not be used in 65186 mode because it conflicts with
2735 the 65816 instruction syntax for far addressing. See the section covering
2736 <tt/<ref id="address-sizes" name="address sizes">/ for more information.
2738 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2740 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2741 comment terminators. Note that C comments may not be nested. There's also a
2742 pitfall when using C like comments: All statements must be terminated by
2743 "end-of-line". Using C like comments, it is possible to hide the newline,
2744 which results in error messages. See the following non working example:
2747 lda #$00 /* This comment hides the newline
2751 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2753 Accept the dollar sign (`$') as a valid character in identifiers. The
2754 dollar character is not allowed to start an identifier, even with this
2757 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2759 The dollar sign may be used as an alias for the star (`*'), which
2760 gives the value of the current PC in expressions.
2761 Note: Assignment to the pseudo variable is not allowed.
2763 <tag><tt>force_range</tt><label id="force_range"></tag>
2765 Force expressions into their valid range for immediate addressing and
2766 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2767 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2768 since it will completely disable error checks.
2770 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2772 Allow labels without a trailing colon. These labels are only accepted,
2773 if they start at the beginning of a line (no leading white space).
2775 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2777 Accept the dot (`.') as the first character of an identifier. This may be
2778 used for example to create macro names that start with a dot emulating
2779 control directives of other assemblers. Note however, that none of the
2780 reserved keywords built into the assembler, that starts with a dot, may be
2781 overridden. When using this feature, you may also get into trouble if
2782 later versions of the assembler define new keywords starting with a dot.
2784 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2786 Accept single quotes as well as double quotes as terminators for char
2789 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2791 Accept single quotes as well as double quotes as terminators for string
2794 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2796 Accept single quoted character constants where the terminating quote is
2801 <em/Note:/ This does not work in conjunction with <tt/.FEATURE
2802 loose_string_term/, since in this case the input would be ambiguous.
2804 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2806 This feature makes relocatable/absolute mode local to the current segment.
2807 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2808 effect will only enable absolute mode for the current segment. Dito for
2809 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2811 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2813 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2814 is enabled). Such an assignment is handled identical to the <tt><ref
2815 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2816 removing the lines with the assignments may also be an option when porting
2817 code written for older assemblers).
2819 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2821 Allow the use of instructions names as names for macros and symbols. This
2822 makes it possible to "overload" instructions by defining a macro with the
2823 same name. This does also make it possible to introduce hard to find errors
2824 in your code, so be careful!
2826 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2828 Allow underlines within numeric constants. These may be used for grouping
2829 the digits of numbers for easier reading.
2832 .feature underline_in_numbers
2833 .word %1100001110100101
2834 .word %1100_0011_1010_0101 ; Identical but easier to read
2839 It is also possible to specify features on the command line using the
2840 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2841 This is useful when translating sources written for older assemblers, when
2842 you don't want to change the source code.
2844 As an example, to translate sources written for Andre Fachats xa65
2845 assembler, the features
2848 labels_without_colons, pc_assignment, loose_char_term
2851 may be helpful. They do not make ca65 completely compatible, so you may not
2852 be able to translate the sources without changes, even when enabling these
2853 features. However, I have found several sources that translate without
2854 problems when enabling these features on the command line.
2857 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2859 Insert an option string into the object file. There are two forms of
2860 this command, one specifies the option by a keyword, the second
2861 specifies it as a number. Since usage of the second one needs knowledge
2862 of the internal encoding, its use is not recommended and I will only
2863 describe the first form here.
2865 The command is followed by one of the keywords
2873 a comma and a string. The option is written into the object file
2874 together with the string value. This is currently unidirectional and
2875 there is no way to actually use these options once they are in the
2881 .fileopt comment, "Code stolen from my brother"
2882 .fileopt compiler, "BASIC 2.0"
2883 .fopt author, "J. R. User"
2887 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2889 Import an absolute symbol from another module. The command is followed by a
2890 comma separated list of symbols to import. The command is similar to <tt>
2891 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2892 written to the generated object file, even if the symbol is never referenced
2893 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2894 references for unused symbols).
2899 .forceimport needthisone, needthistoo
2902 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2905 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2907 Declare symbols as global. Must be followed by a comma separated list of
2908 symbols to declare. Symbols from the list, that are defined somewhere in the
2909 source, are exported, all others are imported. Additional <tt><ref
2910 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2911 name=".EXPORT"></tt> commands for the same symbol are allowed.
2920 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2922 Declare symbols as global. Must be followed by a comma separated list of
2923 symbols to declare. Symbols from the list, that are defined somewhere in the
2924 source, are exported, all others are imported. Additional <tt><ref
2925 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2926 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2927 in the list are explicitly marked as zero page symbols.
2935 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2937 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2938 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2939 the operator '>' prepended to each expression in its list.
2944 .lobytes $1234, $2345, $3456, $4567
2945 .hibytes $fedc, $edcb, $dcba, $cba9
2948 which is equivalent to
2951 .byte $34, $45, $56, $67
2952 .byte $fe, $ed, $dc, $cb
2958 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2960 TableLookupLo: .lobytes MyTable
2961 TableLookupHi: .hibytes MyTable
2964 which is equivalent to
2967 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2968 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2971 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2972 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2973 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2976 <sect1><tt>.I16</tt><label id=".I16"><p>
2978 Valid only in 65816 mode. Switch the index registers to 16 bit.
2980 Note: This command will not emit any code, it will tell the assembler to
2981 create 16 bit operands for immediate operands.
2983 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2984 name=".SMART"></tt> commands.
2987 <sect1><tt>.I8</tt><label id=".I8"><p>
2989 Valid only in 65816 mode. Switch the index registers to 8 bit.
2991 Note: This command will not emit any code, it will tell the assembler to
2992 create 8 bit operands for immediate operands.
2994 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2995 name=".SMART"></tt> commands.
2998 <sect1><tt>.IF</tt><label id=".IF"><p>
3000 Conditional assembly: Evaluate an expression and switch assembler output
3001 on or off depending on the expression. The expression must be a constant
3002 expression, that is, all operands must be defined.
3004 A expression value of zero evaluates to FALSE, any other value evaluates
3008 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
3010 Conditional assembly: Check if there are any remaining tokens in this line,
3011 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
3012 condition is not true, further lines are not assembled until an <tt><ref
3013 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3014 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3016 This command is often used to check if a macro parameter was given. Since an
3017 empty macro parameter will evaluate to nothing, the condition will evaluate
3018 to TRUE if an empty parameter was given.
3032 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3035 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
3037 Conditional assembly: Evaluate an expression and switch assembler output
3038 on or off depending on the constness of the expression.
3040 A const expression evaluates to to TRUE, a non const expression (one
3041 containing an imported or currently undefined symbol) evaluates to
3044 See also: <tt><ref id=".CONST" name=".CONST"></tt>
3047 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
3049 Conditional assembly: Check if a symbol is defined. Must be followed by
3050 a symbol name. The condition is true if the the given symbol is already
3051 defined, and false otherwise.
3053 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3056 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
3058 Conditional assembly: Check if there are any remaining tokens in this line,
3059 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
3060 condition is not true, further lines are not assembled until an <tt><ref
3061 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3062 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3064 This command is often used to check if a macro parameter was given.
3065 Since an empty macro parameter will evaluate to nothing, the condition
3066 will evaluate to FALSE if an empty parameter was given.
3079 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3082 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
3084 Conditional assembly: Check if a symbol is defined. Must be followed by
3085 a symbol name. The condition is true if the the given symbol is not
3086 defined, and false otherwise.
3088 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3091 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
3093 Conditional assembly: Check if a symbol is referenced. Must be followed
3094 by a symbol name. The condition is true if if the the given symbol was
3095 not referenced before, and false otherwise.
3097 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3100 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
3102 Conditional assembly: Check if the assembler is currently in 6502 mode
3103 (see <tt><ref id=".P02" name=".P02"></tt> command).
3106 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
3108 Conditional assembly: Check if the assembler is currently in 65816 mode
3109 (see <tt><ref id=".P816" name=".P816"></tt> command).
3112 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
3114 Conditional assembly: Check if the assembler is currently in 65C02 mode
3115 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3118 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3120 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3121 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3124 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3126 Conditional assembly: Check if a symbol is referenced. Must be followed
3127 by a symbol name. The condition is true if if the the given symbol was
3128 referenced before, and false otherwise.
3130 This command may be used to build subroutine libraries in include files
3131 (you may use separate object modules for this purpose too).
3136 .ifref ToHex ; If someone used this subroutine
3137 ToHex: tay ; Define subroutine
3143 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3146 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3148 Import a symbol from another module. The command is followed by a comma
3149 separated list of symbols to import, with each one optionally followed by
3150 an address specification.
3156 .import bar: zeropage
3159 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3162 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3164 Import a symbol from another module. The command is followed by a comma
3165 separated list of symbols to import. The symbols are explicitly imported
3166 as zero page symbols (that is, symbols with values in byte range).
3174 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3177 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3179 Include a file as binary data. The command expects a string argument
3180 that is the name of a file to include literally in the current segment.
3181 In addition to that, a start offset and a size value may be specified,
3182 separated by commas. If no size is specified, all of the file from the
3183 start offset to end-of-file is used. If no start position is specified
3184 either, zero is assumed (which means that the whole file is inserted).
3189 ; Include whole file
3190 .incbin "sprites.dat"
3192 ; Include file starting at offset 256
3193 .incbin "music.dat", $100
3195 ; Read 100 bytes starting at offset 200
3196 .incbin "graphics.dat", 200, 100
3200 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3202 Include another file. Include files may be nested up to a depth of 16.
3211 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3213 Export a symbol and mark it as an interruptor. This may be used together
3214 with the linker to build a table of interruptor subroutines that are called
3217 Note: The linker has a feature to build a table of marked routines, but it
3218 is your code that must call these routines, so just declaring a symbol as
3219 interruptor does nothing by itself.
3221 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3222 need to use an additional <tt/.export/ statement, this is implied by
3223 <tt/.interruptor/. It may have an optional priority that is separated by a
3224 comma. Higher numeric values mean a higher priority. If no priority is
3225 given, the default priority of 7 is used. Be careful when assigning
3226 priorities to your own module constructors so they won't interfere with the
3227 ones in the cc65 library.
3232 .interruptor IrqHandler
3233 .interruptor Handler, 16
3236 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3237 section <ref id="condes" name="Module constructors/destructors"> explaining
3238 the feature in more detail.
3241 <sect1><tt>.ISMNEM, .ISMNEMONIC</tt><label id=".ISMNEMONIC"><p>
3243 Builtin function. The function expects an identifier as argument in braces.
3244 The argument is evaluated, and the function yields "true" if the identifier
3245 is defined as an instruction mnemonic that is recognized by the assembler.
3249 .if .not .ismnemonic(ina)
3258 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3260 Switch on or off line continuations using the backslash character
3261 before a newline. The option is off by default.
3262 Note: Line continuations do not work in a comment. A backslash at the
3263 end of a comment is treated as part of the comment and does not trigger
3265 The command must be followed by a '+' or '-' character to switch the
3266 option on or off respectively.
3271 .linecont + ; Allow line continuations
3274 #$20 ; This is legal now
3278 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3280 Enable output to the listing. The command must be followed by a boolean
3281 switch ("on", "off", "+" or "-") and will enable or disable listing
3283 The option has no effect if the listing is not enabled by the command line
3284 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3285 to the listing file, if the counter is greater than zero, and suppressed if
3286 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3292 .list on ; Enable listing output
3296 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3298 Set, how many bytes are shown in the listing for one source line. The
3299 default is 12, so the listing will show only the first 12 bytes for any
3300 source line that generates more than 12 bytes of code or data.
3301 The directive needs an argument, which is either "unlimited", or an
3302 integer constant in the range 4..255.
3307 .listbytes unlimited ; List all bytes
3308 .listbytes 12 ; List the first 12 bytes
3309 .incbin "data.bin" ; Include large binary file
3313 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3315 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3316 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3317 the operator '<' prepended to each expression in its list.
3322 .lobytes $1234, $2345, $3456, $4567
3323 .hibytes $fedc, $edcb, $dcba, $cba9
3326 which is equivalent to
3329 .byte $34, $45, $56, $67
3330 .byte $fe, $ed, $dc, $cb
3336 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3338 TableLookupLo: .lobytes MyTable
3339 TableLookupHi: .hibytes MyTable
3342 which is equivalent to
3345 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3346 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3349 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3350 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3351 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3354 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3356 This command may only be used inside a macro definition. It declares a
3357 list of identifiers as local to the macro expansion.
3359 A problem when using macros are labels: Since they don't change their name,
3360 you get a "duplicate symbol" error if the macro is expanded the second time.
3361 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3362 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3365 Some other assemblers start a new lexical block inside a macro expansion.
3366 This has some drawbacks however, since that will not allow <em/any/ symbol
3367 to be visible outside a macro, a feature that is sometimes useful. The
3368 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3369 to address the problem.
3371 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3375 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3377 Defines the character that start "cheap" local labels. You may use one
3378 of '@' and '?' as start character. The default is '@'.
3380 Cheap local labels are labels that are visible only between two non
3381 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3382 using explicit lexical nesting.
3389 Clear: lda #$00 ; Global label
3390 ?Loop: sta Mem,y ; Local label
3394 Sub: ... ; New global label
3395 bne ?Loop ; ERROR: Unknown identifier!
3399 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3401 Insert a predefined macro package. The command is followed by an
3402 identifier specifying the macro package to insert. Available macro
3406 atari Defines the scrcode macro.
3407 cbm Defines the scrcode macro.
3408 cpu Defines constants for the .CPU variable.
3409 generic Defines generic macroes like add, sub, and blt.
3410 longbranch Defines conditional long-jump macroes.
3413 Including a macro package twice, or including a macro package that
3414 redefines already existing macros will lead to an error.
3419 .macpack longbranch ; Include macro package
3421 cmp #$20 ; Set condition codes
3422 jne Label ; Jump long on condition
3425 Macro packages are explained in more detail in section <ref
3426 id="macropackages" name="Macro packages">.
3429 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3431 Start a classic macro definition. The command is followed by an identifier
3432 (the macro name) and optionally by a comma separated list of identifiers
3433 that are macro parameters. A macro definition is terminated by <tt><ref
3434 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3439 .macro ldax arg ; Define macro ldax
3444 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3445 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3446 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3448 See also section <ref id="macros" name="Macros">.
3451 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3453 Start a section of absolute code. The command is followed by a constant
3454 expression that gives the new PC counter location for which the code is
3455 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3458 By default, absolute/relocatable mode is global (valid even when switching
3459 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3460 it can be made segment local.
3462 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3463 code at a specific address is the job of the linker, not the assembler, so
3464 there is usually no reason to assemble code to a specific address.
3469 .org $7FF ; Emit code starting at $7FF
3473 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3475 Output a string to the console without producing an error. This command
3476 is similar to <tt/.ERROR/, however, it does not force an assembler error
3477 that prevents the creation of an object file.
3482 .out "This code was written by the codebuster(tm)"
3485 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3486 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3487 <tt><ref id=".WARNING" name=".WARNING"></tt>
3490 <sect1><tt>.P02</tt><label id=".P02"><p>
3492 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3493 instructions. This is the default if not overridden by the
3494 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3496 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3497 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3500 <sect1><tt>.P816</tt><label id=".P816"><p>
3502 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3503 6502 instruction sets.
3505 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3506 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3509 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3511 Set the page length for the listing. Must be followed by an integer
3512 constant. The value may be "unlimited", or in the range 32 to 127. The
3513 statement has no effect if no listing is generated. The default value is -1
3514 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3515 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3516 after assembly is complete, you cannot use multiple line lengths with one
3517 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3522 .pagelength 66 ; Use 66 lines per listing page
3524 .pagelength unlimited ; Unlimited page length
3528 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3530 Enable the 65C02 instructions set. This instruction set includes all
3531 6502 and 65SC02 instructions.
3533 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3534 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3537 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3539 Pop the last CPU setting from the stack, and activate it.
3541 This command will switch back to the CPU that was last pushed onto the CPU
3542 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3543 remove this entry from the stack.
3545 The assembler will print an error message if the CPU stack is empty when
3546 this command is issued.
3548 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3549 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3552 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3554 Pop the last pushed segment from the stack, and set it.
3556 This command will switch back to the segment that was last pushed onto the
3557 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3558 command, and remove this entry from the stack.
3560 The assembler will print an error message if the segment stack is empty
3561 when this command is issued.
3563 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3566 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3568 Start a nested lexical level with the given name and adds a symbol with this
3569 name to the enclosing scope. All new symbols from now on are in the local
3570 lexical level and are accessible from outside only via <ref id="scopesyntax"
3571 name="explicit scope specification">. Symbols defined outside this local
3572 level may be accessed as long as their names are not used for new symbols
3573 inside the level. Symbols names in other lexical levels do not clash, so you
3574 may use the same names for identifiers. The lexical level ends when the
3575 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3576 may be nested up to a depth of 16 (this is an artificial limit to protect
3577 against errors in the source).
3579 Note: Macro names are always in the global level and in a separate name
3580 space. There is no special reason for this, it's just that I've never
3581 had any need for local macro definitions.
3586 .proc Clear ; Define Clear subroutine, start new level
3588 L1: sta Mem,y ; L1 is local and does not cause a
3589 ; duplicate symbol error if used in other
3592 bne L1 ; Reference local symbol
3594 .endproc ; Leave lexical level
3597 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3601 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3603 Enable the 65SC02 instructions set. This instruction set includes all
3606 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3607 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3610 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3612 Push the currently active CPU onto a stack. The stack has a size of 8
3615 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3616 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3617 later, without knowledge of the current CPU setting.
3619 The assembler will print an error message if the CPU stack is already full,
3620 when this command is issued.
3622 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3623 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3626 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3628 Push the currently active segment onto a stack. The entries on the stack
3629 include the name of the segment and the segment type. The stack has a size
3632 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3633 to switch to another segment and to restore the old segment later, without
3634 even knowing the name and type of the current segment.
3636 The assembler will print an error message if the segment stack is already
3637 full, when this command is issued.
3639 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3642 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3644 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3645 name=".ORG"></tt> command.
3648 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3650 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3651 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3652 a constant expression that tells how many times the commands in the body
3653 should get repeated. Optionally, a comma and an identifier may be specified.
3654 If this identifier is found in the body of the repeat statement, it is
3655 replaced by the current repeat count (starting with zero for the first time
3656 the body is repeated).
3658 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3659 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3660 level will be used, not the one from the outer level.
3664 The following macro will emit a string that is "encrypted" in that all
3665 characters of the string are XORed by the value $55.
3669 .repeat .strlen(Arg), I
3670 .byte .strat(Arg, I) ^ $55
3675 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3678 <sect1><tt>.RES</tt><label id=".RES"><p>
3680 Reserve storage. The command is followed by one or two constant
3681 expressions. The first one is mandatory and defines, how many bytes of
3682 storage should be defined. The second, optional expression must by a
3683 constant byte value that will be used as value of the data. If there
3684 is no fill value given, the linker will use the value defined in the
3685 linker configuration file (default: zero).
3690 ; Reserve 12 bytes of memory with value $AA
3695 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3697 Switch to the RODATA segment. The name of the RODATA segment is always
3698 "RODATA", so this is a shortcut for
3704 The RODATA segment is a segment that is used by the compiler for
3705 readonly data like string constants.
3707 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3710 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3712 Start a nested lexical level with the given name. All new symbols from now
3713 on are in the local lexical level and are accessible from outside only via
3714 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3715 outside this local level may be accessed as long as their names are not used
3716 for new symbols inside the level. Symbols names in other lexical levels do
3717 not clash, so you may use the same names for identifiers. The lexical level
3718 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3719 read. Lexical levels may be nested up to a depth of 16 (this is an
3720 artificial limit to protect against errors in the source).
3722 Note: Macro names are always in the global level and in a separate name
3723 space. There is no special reason for this, it's just that I've never
3724 had any need for local macro definitions.
3729 .scope Error ; Start new scope named Error
3731 File = 1 ; File error
3732 Parse = 2 ; Parse error
3733 .endscope ; Close lexical level
3736 lda #Error::File ; Use symbol from scope Error
3739 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3743 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3745 Switch to another segment. Code and data is always emitted into a
3746 segment, that is, a named section of data. The default segment is
3747 "CODE". There may be up to 254 different segments per object file
3748 (and up to 65534 per executable). There are shortcut commands for
3749 the most common segments ("ZEROPAGE", "CODE", "RODATA", "DATA", and "BSS").
3751 The command is followed by a string containing the segment name (there are
3752 some constraints for the name - as a rule of thumb use only those segment
3753 names that would also be valid identifiers). There may also be an optional
3754 address size separated by a colon. See the section covering <tt/<ref
3755 id="address-sizes" name="address sizes">/ for more information.
3757 The default address size for a segment depends on the memory model specified
3758 on the command line. The default is "absolute", which means that you don't
3759 have to use an address size modifier in most cases.
3761 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3762 That is, the segment will reside somewhere in core memory outside the zero
3763 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3764 page and direct (short) addressing is possible for data in this segment.
3766 Beware: Only labels in a segment with the zeropage attribute are marked
3767 as reachable by short addressing. The `*' (PC counter) operator will
3768 work as in other segments and will create absolute variable values.
3770 Please note that a segment cannot have two different address sizes. A
3771 segment specified as zeropage cannot be declared as being absolute later.
3776 .segment "ROM2" ; Switch to ROM2 segment
3777 .segment "ZP2": zeropage ; New direct segment
3778 .segment "ZP2" ; Ok, will use last attribute
3779 .segment "ZP2": absolute ; Error, redecl mismatch
3782 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3783 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt>, <tt><ref
3784 id=".RODATA" name=".RODATA"></tt>, and <tt><ref id=".ZEROPAGE"
3785 name=".ZEROPAGE"></tt>
3788 <sect1><tt>.SET</tt><label id=".SET"><p>
3790 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3791 name="Numeric variables"> for a full description.
3794 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3796 Switch the CPU instruction set. The command is followed by a string that
3797 specifies the CPU. Possible values are those that can also be supplied to
3798 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3799 namely: 6502, 6502X, 65SC02, 65C02, 65816 and HuC6280.
3801 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3802 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3803 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3804 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3805 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3806 <tt><ref id=".P02" name=".P02"></tt>,
3807 <tt><ref id=".P816" name=".P816"></tt>,
3808 <tt><ref id=".PC02" name=".PC02"></tt>,
3809 <tt><ref id=".PSC02" name=".PSC02"></tt>
3812 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3814 Switch on or off smart mode. The command must be followed by a '+' or '-'
3815 character to switch the option on or off respectively. The default is off
3816 (that is, the assembler doesn't try to be smart), but this default may be
3817 changed by the -s switch on the command line.
3819 In smart mode the assembler will do the following:
3822 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3823 and update the operand sizes accordingly. If the operand of such an
3824 instruction cannot be evaluated by the assembler (for example, because
3825 the operand is an imported symbol), a warning is issued. Beware: Since
3826 the assembler cannot trace the execution flow this may lead to false
3827 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3828 instructions to tell the assembler about the current settings.
3829 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3830 used within a procedure declared as <tt/far/, or if the procedure has
3831 no explicit address specification, but it is <tt/far/ because of the
3839 .smart - ; Stop being smart
3842 See: <tt><ref id=".A16" name=".A16"></tt>,
3843 <tt><ref id=".A8" name=".A8"></tt>,
3844 <tt><ref id=".I16" name=".I16"></tt>,
3845 <tt><ref id=".I8" name=".I8"></tt>
3848 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3850 Starts a struct definition. Structs are covered in a separate section named
3851 <ref id="structs" name=""Structs and unions"">.
3853 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3854 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3855 <tt><ref id=".UNION" name=".UNION"></tt>
3858 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3860 Allocate space for a struct or union.
3871 .tag Point ; Allocate 4 bytes
3875 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3877 Delete a define style macro definition. The command is followed by an
3878 identifier which specifies the name of the macro to delete. Macro
3879 replacement is switched of when reading the token following the command
3880 (otherwise the macro name would be replaced by its replacement list).
3882 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3883 section <ref id="macros" name="Macros">.
3886 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3888 Starts a union definition. Unions are covered in a separate section named
3889 <ref id="structs" name=""Structs and unions"">.
3891 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3892 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3893 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3896 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3898 Force an assembly warning. The assembler will output a warning message
3899 preceded by "User warning". This warning will always be output, even if
3900 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3901 command line option.
3903 This command may be used to output possible problems when assembling
3912 .warning "Forward jump in jne, cannot optimize!"
3922 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3923 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3924 <tt><ref id=".OUT" name=".OUT"></tt>
3927 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3929 Define word sized data. Must be followed by a sequence of (word ranged,
3930 but not necessarily constant) expressions.
3935 .word $0D00, $AF13, _Clear
3939 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3941 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3942 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3946 .segment "ZEROPAGE": zeropage
3949 Because of the "zeropage" attribute, labels declared in this segment are
3950 addressed using direct addressing mode if possible. You <em/must/ instruct
3951 the linker to place this segment somewhere in the address range 0..$FF
3952 otherwise you will get errors.
3954 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3958 <sect>Macros<label id="macros"><p>
3961 <sect1>Introduction<p>
3963 Macros may be thought of as "parametrized super instructions". Macros are
3964 sequences of tokens that have a name. If that name is used in the source
3965 file, the macro is "expanded", that is, it is replaced by the tokens that
3966 were specified when the macro was defined.
3969 <sect1>Macros without parameters<p>
3971 In its simplest form, a macro does not have parameters. Here's an
3975 .macro asr ; Arithmetic shift right
3976 cmp #$80 ; Put bit 7 into carry
3977 ror ; Rotate right with carry
3981 The macro above consists of two real instructions, that are inserted into
3982 the code, whenever the macro is expanded. Macro expansion is simply done
3983 by using the name, like this:
3992 <sect1>Parametrized macros<p>
3994 When using macro parameters, macros can be even more useful:
4008 When calling the macro, you may give a parameter, and each occurrence of
4009 the name "addr" in the macro definition will be replaced by the given
4028 A macro may have more than one parameter, in this case, the parameters
4029 are separated by commas. You are free to give less parameters than the
4030 macro actually takes in the definition. You may also leave intermediate
4031 parameters empty. Empty parameters are replaced by empty space (that is,
4032 they are removed when the macro is expanded). If you have a look at our
4033 macro definition above, you will see, that replacing the "addr" parameter
4034 by nothing will lead to wrong code in most lines. To help you, writing
4035 macros with a variable parameter list, there are some control commands:
4037 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
4038 returns true, if there are any tokens on the remainder of the line. Since
4039 empty parameters are replaced by nothing, this may be used to test if a given
4040 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
4043 Look at this example:
4046 .macro ldaxy a, x, y
4059 That macro may be called as follows:
4062 ldaxy 1, 2, 3 ; Load all three registers
4064 ldaxy 1, , 3 ; Load only a and y
4066 ldaxy , , 3 ; Load y only
4069 There's another helper command for determining which macro parameters are
4070 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>. That command is
4071 replaced by the parameter count given, <em/including/ explicitly empty
4075 ldaxy 1 ; .PARAMCOUNT = 1
4076 ldaxy 1,,3 ; .PARAMCOUNT = 3
4077 ldaxy 1,2 ; .PARAMCOUNT = 2
4078 ldaxy 1, ; .PARAMCOUNT = 2
4079 ldaxy 1,2,3 ; .PARAMCOUNT = 3
4082 Macro parameters may optionally be enclosed into curly braces. This allows the
4083 inclusion of tokens that would otherwise terminate the parameter (the comma in
4084 case of a macro parameter).
4087 .macro foo arg1, arg2
4091 foo ($00,x) ; Two parameters passed
4092 foo {($00,x)} ; One parameter passed
4095 In the first case, the macro is called with two parameters: '<tt/($00/'
4096 and '<tt/x)/'. The comma is not passed to the macro, because it is part of the
4097 calling sequence, not the parameters.
4099 In the second case, '<tt/($00,x)/' is passed to the macro; this time,
4100 including the comma.
4103 <sect1>Detecting parameter types<p>
4105 Sometimes it is nice to write a macro that acts differently depending on the
4106 type of the argument supplied. An example would be a macro that loads a 16 bit
4107 value from either an immediate operand, or from memory. The <tt/<ref
4108 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
4109 functions will allow you to do exactly this:
4113 .if (.match (.left (1, {arg}), #))
4115 lda #<(.right (.tcount ({arg})-1, {arg}))
4116 ldx #>(.right (.tcount ({arg})-1, {arg}))
4118 ; assume absolute or zero page
4125 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4126 check if its argument begins with a hash mark. If so, two immediate loads are
4127 emitted, Otherwise a load from an absolute zero page memory location is
4128 assumed. Please note how the curly braces are used to enclose parameters to
4129 pseudo functions handling token lists. This is necessary, because the token
4130 lists may include commas or parens, which would be treated by the assembler
4133 The macro can be used as
4138 ldax #$1234 ; X=$12, A=$34
4140 ldax foo ; X=$56, A=$78
4144 <sect1>Recursive macros<p>
4146 Macros may be used recursively:
4149 .macro push r1, r2, r3
4158 There's also a special macro command to help with writing recursive macros:
4159 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>. That command will stop macro
4160 expansion immediately:
4163 .macro push r1, r2, r3, r4, r5, r6, r7
4165 ; First parameter is empty
4171 push r2, r3, r4, r5, r6, r7
4175 When expanding that macro, the expansion will push all given parameters
4176 until an empty one is encountered. The macro may be called like this:
4179 push $20, $21, $32 ; Push 3 ZP locations
4180 push $21 ; Push one ZP location
4184 <sect1>Local symbols inside macros<p>
4186 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4187 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4188 Have a look at the inc16 macro above. Here is it again:
4202 If you have a closer look at the code, you will notice, that it could be
4203 written more efficiently, like this:
4214 But imagine what happens, if you use this macro twice? Since the label "Skip"
4215 has the same name both times, you get a "duplicate symbol" error. Without a
4216 way to circumvent this problem, macros are not as useful, as they could be.
4217 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4218 It declares one or more symbols as local to the macro expansion. The names of
4219 local variables are replaced by a unique name in each separate macro
4220 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4224 .local Skip ; Make Skip a local symbol
4228 Skip: ; Not visible outside
4232 Another solution is of course to start a new lexical block inside the macro
4233 that hides any labels:
4247 <sect1>C style macros<p>
4249 Starting with version 2.5 of the assembler, there is a second macro type
4250 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4251 similar to the classic macro type described above, but behaviour is sometimes
4256 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4257 span more than a line. You may use line continuation (see <tt><ref
4258 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4259 more than one line for increased readability, but the macro itself
4260 may not contain an end-of-line token.
4262 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4263 the name space with classic macros, but they are detected and replaced
4264 at the scanner level. While classic macros may be used in every place,
4265 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4266 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4267 they are more versatile in some situations.
4269 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4270 parameters. While classic macros may have empty parameters, this is
4271 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4272 For this macro type, the number of actual parameters must match
4273 exactly the number of formal parameters.
4275 To make this possible, formal parameters are enclosed in braces when
4276 defining the macro. If there are no parameters, the empty braces may
4279 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4280 contain end-of-line tokens, there are things that cannot be done. They
4281 may not contain several processor instructions for example. So, while
4282 some things may be done with both macro types, each type has special
4283 usages. The types complement each other.
4285 <item> Parentheses work differently from C macros.
4286 The common practice of wrapping C macros in parentheses may cause
4287 unintended problems here, such as accidentally implying an
4288 indirect addressing mode. While the definition of a macro requires
4289 parentheses around its argument list, when invoked they should not be included.
4293 Let's look at a few examples to make the advantages and disadvantages
4296 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4297 following <tt/.DEFINE/:
4302 foo EQU $1234 ; This is accepted now
4305 You may use the directive to define string constants used elsewhere:
4308 ; Define the version number
4309 .define VERSION "12.3a"
4315 Macros with parameters may also be useful:
4318 .define DEBUG(message) .out message
4320 DEBUG "Assembling include file #3"
4323 Note that, while formal parameters have to be placed in braces,
4324 the actual parameters used when invoking the macro should not use braces.
4325 The invoked parameters are separated by commas only, if parentheses are
4326 used by accident they will become part of the replaced token:
4329 .define COMBINE(ta,tb,tc) ta+tb*10+tc*100
4331 COMBINE 5,6,7 ; 5+6*10+7*100 = 765 correct
4332 COMBINE(5,6,7) ; (5+6*10+7)*100 = 7200 incorrect!
4335 <sect1>Characters in macros<p>
4337 When using the <ref id="option-t" name="-t"> option, characters are translated
4338 into the target character set of the specific machine. However, this happens
4339 as late as possible. This means that strings are translated if they are part
4340 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4341 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4342 used as part of an expression.
4344 This behaviour is very intuitive outside of macros but may be confusing when
4345 doing more complex macros. If you compare characters against numeric values,
4346 be sure to take the translation into account.
4349 <sect1>Deleting macros<p>
4351 Macros can be deleted. This will not work if the macro that should be deleted
4352 is currently expanded as in the following non-working example:
4356 .delmacro notworking
4359 notworking ; Will not work
4362 The commands to delete classic and define style macros differ. Classic macros
4363 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4364 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4365 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4373 .byte value ; Emit one byte with value 1
4374 mac ; Emit another byte with value 2
4379 .byte value ; Error: Unknown identifier
4380 mac ; Error: Missing ":"
4383 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4384 the name of such a macro is replaced by its replacement list on a very low
4385 level. To get the actual name, macro replacement has to be switched off when
4386 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4387 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4388 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4389 different commands increases flexibility.
4393 <sect>Macro packages<label id="macropackages"><p>
4395 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4396 macro packages may be included with just one command. Available macro packages
4400 <sect1><tt>.MACPACK generic</tt><p>
4402 This macro package defines macroes that are useful in almost any program.
4403 Currently defined macroes are:
4406 .macro add Arg ; add without carry
4411 .macro sub Arg ; subtract without borrow
4416 .macro bge Arg ; branch on greater-than or equal
4420 .macro blt Arg ; branch on less-than
4424 .macro bgt Arg ; branch on greater-than
4431 .macro ble Arg ; branch on less-than or equal
4436 .macro bnz Arg ; branch on not zero
4440 .macro bze Arg ; branch on zero
4446 <sect1><tt>.MACPACK longbranch</tt><p>
4448 This macro package defines long conditional jumps. They are named like the
4449 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4450 definition for the "<tt/jeq/" macro, the other macros are built using the same
4455 .if .def(Target) .and ((*+2)-(Target) <= 127)
4464 All macros expand to a short branch, if the label is already defined (back
4465 jump) and is reachable with a short jump. Otherwise the macro expands to a
4466 conditional branch with the branch condition inverted, followed by an absolute
4467 jump to the actual branch target.
4469 The package defines the following macros:
4472 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4477 <sect1><tt>.MACPACK apple2</tt><p>
4479 This macro package defines a macro named <tt/scrcode/. It takes a string
4480 as argument and places this string into memory translated into screen codes.
4483 <sect1><tt>.MACPACK atari</tt><p>
4485 This macro package defines a macro named <tt/scrcode/. It takes a string
4486 as argument and places this string into memory translated into screen codes.
4489 <sect1><tt>.MACPACK cbm</tt><p>
4491 This macro package defines a macro named <tt/scrcode/. It takes a string
4492 as argument and places this string into memory translated into screen codes.
4495 <sect1><tt>.MACPACK cpu</tt><p>
4497 This macro package does not define any macros but constants used to examine
4498 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4499 each supported CPU a constant similar to
4510 is defined. These constants may be used to determine the exact type of the
4511 currently enabled CPU. In addition to that, for each CPU instruction set,
4512 another constant is defined:
4523 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4524 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4525 currently enabled CPU supports a specific instruction set. For example the
4526 65C02 supports all instructions of the 65SC02 CPU, so it has the
4527 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4531 .if (.cpu .bitand CPU_ISET_65SC02)
4539 it is possible to determine if the
4545 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4546 CPUs (the latter two are upwards compatible to the 65SC02).
4549 <sect1><tt>.MACPACK module</tt><p>
4551 This macro package defines a macro named <tt/module_header/. It takes an
4552 identifier as argument and is used to define the header of a module both
4553 in the dynamic and static variant.
4557 <sect>Predefined constants<label id="predefined-constants"><p>
4559 For better orthogonality, the assembler defines similar symbols as the
4560 compiler, depending on the target system selected:
4563 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4564 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4565 <item><tt/__ATARI5200__/ - Target system is <tt/atari5200/
4566 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4567 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4568 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4569 <item><tt/__BBC__/ - Target system is <tt/bbc/
4570 <item><tt/__C128__/ - Target system is <tt/c128/
4571 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4572 <item><tt/__C64__/ - Target system is <tt/c64/
4573 <item><tt/__CBM__/ - Target is a Commodore system
4574 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4575 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4576 <item><tt/__GEOS__/ - Target is a GEOS system
4577 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4578 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4579 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4580 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4581 <item><tt/__NES__/ - Target system is <tt/nes/
4582 <item><tt/__OSIC1P__/ - Target system is <tt/osic1p/
4583 <item><tt/__PET__/ - Target system is <tt/pet/
4584 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4585 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4586 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4587 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4588 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4592 <sect>Structs and unions<label id="structs"><p>
4594 <sect1>Structs and unions Overview<p>
4596 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4597 are to some degree comparable to their C counterparts. Both have a list of
4598 members. Each member allocates storage and may optionally have a name, which,
4599 in case of a struct, is the offset from the beginning and, in case of a union,
4603 <sect1>Declaration<p>
4605 Here is an example for a very simple struct with two members and a total size
4615 A union shares the total space between all its members, its size is the same
4616 as that of the largest member. The offset of all members relative to the union
4626 A struct or union must not necessarily have a name. If it is anonymous, no
4627 local scope is opened, the identifiers used to name the members are placed
4628 into the current scope instead.
4630 A struct may contain unnamed members and definitions of local structs. The
4631 storage allocators may contain a multiplier, as in the example below:
4636 .word 2 ; Allocate two words
4643 <sect1>The <tt/.TAG/ keyword<p>
4645 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4646 for an already defined struct or unions within another struct:
4660 Space for a struct or union may be allocated using the <ref id=".TAG"
4661 name=".TAG"> directive.
4667 Currently, members are just offsets from the start of the struct or union. To
4668 access a field of a struct, the member offset has to be added to the address
4669 of the struct itself:
4672 lda C+Circle::Radius ; Load circle radius into A
4675 This may change in a future version of the assembler.
4678 <sect1>Limitations<p>
4680 Structs and unions are currently implemented as nested symbol tables (in fact,
4681 they were a by-product of the improved scoping rules). Currently, the
4682 assembler has no idea of types. This means that the <ref id=".TAG"
4683 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4684 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4685 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4686 this structure accessible by using the '::' operator.
4690 <sect>Module constructors/destructors<label id="condes"><p>
4692 <em>Note:</em> This section applies mostly to C programs, so the explanation
4693 below uses examples from the C libraries. However, the feature may also be
4694 useful for assembler programs.
4697 <sect1>Module constructors/destructors Overview<p>
4699 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4700 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4701 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4702 special way. The linker is able to generate tables with all functions of a
4703 specific type. Such a table will <em>only</em> include symbols from object
4704 files that are linked into a specific executable. This may be used to add
4705 initialization and cleanup code for library modules, or a table of interrupt
4708 The C heap functions are an example where module initialization code is used.
4709 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4710 variables that contain the start and the end of the heap, pointers to the free
4711 list and so on. Since the end of the heap depends on the size and start of the
4712 stack, it must be initialized at runtime. However, initializing these
4713 variables for programs that do not use the heap are a waste of time and
4716 So the central module defines a function that contains initialization code and
4717 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4718 this module is added to an executable by the linker, the initialization
4719 function will be placed into the table of constructors by the linker. The C
4720 startup code will call all constructors before <tt/main/ and all destructors
4721 after <tt/main/, so without any further work, the heap initialization code is
4722 called once the module is linked in.
4724 While it would be possible to add explicit calls to initialization functions
4725 in the startup code, the new approach has several advantages:
4729 If a module is not included, the initialization code is not linked in and not
4730 called. So you don't pay for things you don't need.
4733 Adding another library that needs initialization does not mean that the
4734 startup code has to be changed. Before we had module constructors and
4735 destructors, the startup code for all systems had to be adjusted to call the
4736 new initialization code.
4739 The feature saves memory: Each additional initialization function needs just
4740 two bytes in the table (a pointer to the function).
4745 <sect1>Calling order<p>
4747 The symbols are sorted in increasing priority order by the linker when using
4748 one of the builtin linker configurations, so the functions with lower
4749 priorities come first and are followed by those with higher priorities. The C
4750 library runtime subroutine that walks over the function tables calls the
4751 functions starting from the top of the table - which means that functions with
4752 a high priority are called first.
4754 So when using the C runtime, functions are called with high priority functions
4755 first, followed by low priority functions.
4760 When using these special symbols, please take care of the following:
4765 The linker will only generate function tables, it will not generate code to
4766 call these functions. If you're using the feature in some other than the
4767 existing C environments, you have to write code to call all functions in a
4768 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4769 in the C runtime for an example on how to do this.
4772 The linker will only add addresses of functions that are in modules linked to
4773 the executable. This means that you have to be careful where to place the
4774 condes functions. If initialization or an irq handler is needed for a group of
4775 functions, be sure to place the function into a module that is linked in
4776 regardless of which function is called by the user.
4779 The linker will generate the tables only when requested to do so by the
4780 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4781 be requested separately.
4784 Constructors and destructors may have priorities. These priorities determine
4785 the order of the functions in the table. If your initialization or cleanup code
4786 does depend on other initialization or cleanup code, you have to choose the
4787 priority for the functions accordingly.
4790 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4791 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4792 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4793 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4794 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4795 (interruptor). The linker generates a separate table for each type on request.
4800 <sect>Porting sources from other assemblers<p>
4802 Sometimes it is necessary to port code written for older assemblers to ca65.
4803 In some cases, this can be done without any changes to the source code by
4804 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4805 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4808 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4809 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4810 done by the linker. Most other assemblers generate absolute code, placement is
4811 done within the assembler and there is no external linker.
4813 In general it is not a good idea to write new code using the emulation
4814 features of the assembler, but there may be situations where even this rule is
4819 You need to use some of the ca65 emulation features to simulate the behaviour
4820 of such simple assemblers.
4823 <item>Prepare your sourcecode like this:
4826 ; if you want TASS style labels without colons
4827 .feature labels_without_colons
4829 ; if you want TASS style character constants
4830 ; ("a" instead of the default 'a')
4831 .feature loose_char_term
4833 .word *+2 ; the cbm load address
4838 notice that the two emulation features are mostly useful for porting
4839 sources originally written in/for TASS, they are not needed for the
4840 actual "simple assembler operation" and are not recommended if you are
4841 writing new code from scratch.
4843 <item>Replace all program counter assignments (which are not possible in ca65
4844 by default, and the respective emulation feature works different from what
4845 you'd expect) by another way to skip to memory locations, for example the
4846 <tt><ref id=".RES" name=".RES"></tt> directive.
4850 .res $2000-* ; reserve memory up to $2000
4853 Please note that other than the original TASS, ca65 can never move the program
4854 counter backwards - think of it as if you are assembling to disk with TASS.
4856 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4857 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4858 of <tt/.goto/, everything involving loops must be replaced by
4859 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4861 <item>To assemble code to a different address than it is executed at, use the
4862 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4863 <tt/.offs/-constructs.
4870 .reloc ; back to normal
4873 <item>Then assemble like this:
4876 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4879 Note that you need to use the actual start address minus two, since two bytes
4880 are used for the cbm load address.
4887 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4888 Bassewitz. For usage of the binaries and/or sources the following
4889 conditions do apply:
4891 This software is provided 'as-is', without any expressed or implied
4892 warranty. In no event will the authors be held liable for any damages
4893 arising from the use of this software.
4895 Permission is granted to anyone to use this software for any purpose,
4896 including commercial applications, and to alter it and redistribute it
4897 freely, subject to the following restrictions:
4900 <item> The origin of this software must not be misrepresented; you must not
4901 claim that you wrote the original software. If you use this software
4902 in a product, an acknowledgment in the product documentation would be
4903 appreciated but is not required.
4904 <item> Altered source versions must be plainly marked as such, and must not
4905 be misrepresented as being the original software.
4906 <item> This notice may not be removed or altered from any source