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">
9 ca65 is a powerful macro assembler for the 6502, 65C02, and 65816 CPUs. It is
10 used as a companion assembler for the cc65 crosscompiler, but it may also be
11 used as a standalone product.
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
22 compiler, originally developed by John R. Dunning. I had some problems with
23 ra65 and the copyright does not permit some things which I wanted to be
24 possible, so I decided to write a completely new assembler/linker/archiver
25 suite for the cc65 compiler. ca65 is part of this suite.
27 Some parts of the assembler (code generation and some routines for symbol
28 table handling) are taken from an older crossassembler named a816 written
29 by me a long time ago.
32 <sect1>Design criteria<p>
34 Here's a list of the design criteria, that I considered important for the
39 <item> The assembler must support macros. Macros are not essential, but they
40 make some things easier, especially when you use the assembler in the
41 backend of a compiler.
42 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
43 thinking about a 65816 backend for the C compiler, and even my old
44 a816 assembler had support for these CPUs, so this wasn't really a
46 <item> The assembler must produce relocatable code. This is necessary for the
47 compiler support, and it is more convenient.
48 <item> Conditional assembly must be supported. This is a must for bigger
49 projects written in assembler (like Elite128).
50 <item> The assembler must support segments, and it must support more than
51 three segments (this is the count, most other assemblers support).
52 Having more than one code segments helps developing code for systems
53 with a divided ROM area (like the C64).
54 <item> The linker must be able to resolve arbitrary expressions. It should
55 be able to get things like
62 <item> True lexical nesting for symbols. This is very convenient for larger
64 <item> "Cheap" local symbols without lexical nesting for those quick, late
66 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
67 introduced the concept into the object file format use by the new cc65
69 <item> The assembler will be a one pass assembler. There was no real need for
70 this decision, but I've written several multipass assemblers, and it
71 started to get boring. A one pass assembler needs much more elaborated
72 data structures, and because of that it's much more fun:-)
73 <item> Non-GPLed code that may be used in any project without restrictions or
74 fear of "GPL infecting" other code.
82 <sect1>Command line option overview<p>
84 The assembler accepts the following options:
87 ---------------------------------------------------------------------------
88 Usage: ca65 [options] file
90 -D name[=value] Define a symbol
91 -I dir Set an include directory search path
92 -U Mark unresolved symbols as import
93 -V Print the assembler version
94 -W n Set warning level n
96 -g Add debug info to object file
98 -i Ignore case of symbols
99 -l name Create a listing file if assembly was ok
100 -mm model Set the memory model
101 -o name Name the output file
103 -t sys Set the target system
104 -v Increase verbosity
107 --auto-import Mark unresolved symbols as import
108 --bin-include-dir dir Set a search path for binary includes
109 --cpu type Set cpu type
110 --create-dep name Create a make dependency file
111 --create-full-dep name Create a full make dependency file
113 --debug-info Add debug info to object file
114 --feature name Set an emulation feature
115 --help Help (this text)
116 --ignore-case Ignore case of symbols
117 --include-dir dir Set an include directory search path
118 --large-alignment Don't warn about large alignments
119 --listing name Create a listing file if assembly was ok
120 --list-bytes n Maximum number of bytes per listing line
121 --memory-model model Set the memory model
122 --pagelength n Set the page length for the listing
123 --relax-checks Relax some checks (see docs)
124 --smart Enable smart mode
125 --target sys Set the target system
126 --verbose Increase verbosity
127 --version Print the assembler version
128 ---------------------------------------------------------------------------
132 <sect1>Command line options in detail<p>
134 Here is a description of all the command line options:
138 <label id="option--bin-include-dir">
139 <tag><tt>--bin-include-dir dir</tt></tag>
141 Name a directory which is searched for binary include files. The option
142 may be used more than once to specify more than one directory to search. The
143 current directory is always searched first before considering any
144 additional directories. See also the section about <ref id="search-paths"
145 name="search paths">.
148 <label id="option--cpu">
149 <tag><tt>--cpu type</tt></tag>
151 Set the default for the CPU type. The option takes a parameter, which
154 6502, 6502X, 65SC02, 65C02, 65816, sweet16, HuC6280, 4510
157 <label id="option-create-dep">
158 <tag><tt>--create-dep name</tt></tag>
160 Tells the assembler to generate a file containing the dependency list for
161 the assembled module in makefile syntax. The output is written to a file
162 with the given name. The output does not include files passed via debug
163 information to the assembler.
166 <label id="option-create-full-dep">
167 <tag><tt>--create-full-dep name</tt></tag>
169 Tells the assembler to generate a file containing the dependency list for
170 the assembled module in makefile syntax. The output is written to a file
171 with the given name. The output does include files passed via debug
172 information to the assembler.
175 <tag><tt>-d, --debug</tt></tag>
177 Enables debug mode, something that should not be needed for mere
181 <label id="option--feature">
182 <tag><tt>--feature name</tt></tag>
184 Enable an emulation feature. This is identical as using <tt/.FEATURE/
185 in the source with two exceptions: Feature names must be lower case, and
186 each feature must be specified by using an extra <tt/--feature/ option,
187 comma separated lists are not allowed.
189 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
190 command for a list of emulation features.
193 <label id="option-g">
194 <tag><tt>-g, --debug-info</tt></tag>
196 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
197 used, the assembler will add a section to the object file that contains
198 all symbols (including local ones) together with the symbol values and
199 source file positions. The linker will put these additional symbols into
200 the VICE label file, so even local symbols can be seen in the VICE
204 <label id="option-h">
205 <tag><tt>-h, --help</tt></tag>
207 Print the short option summary shown above.
210 <label id="option-i">
211 <tag><tt>-i, --ignore-case</tt></tag>
213 This option makes the assembler case insensitive on identifiers and labels.
214 This option will override the default, but may itself be overridden by the
215 <tt><ref id=".CASE" name=".CASE"></tt> control command.
218 <label id="option-l">
219 <tag><tt>-l name, --listing name</tt></tag>
221 Generate an assembler listing with the given name. A listing file will
222 never be generated in case of assembly errors.
225 <label id="option--large-alignment">
226 <tag><tt>--large-alignment</tt></tag>
228 Disable warnings about a large combined alignment. See the discussion of the
229 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
232 <label id="option--list-bytes">
233 <tag><tt>--list-bytes n</tt></tag>
235 Set the maximum number of bytes printed in the listing for one line of
236 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
237 for more information. The value zero can be used to encode an unlimited
238 number of printed bytes.
241 <label id="option-mm">
242 <tag><tt>-mm model, --memory-model model</tt></tag>
244 Define the default memory model. Possible model specifiers are near, far and
248 <label id="option-o">
249 <tag><tt>-o name</tt></tag>
251 The default output name is the name of the input file with the extension
252 replaced by ".o". If you don't like that, you may give another name with
253 the -o option. The output file will be placed in the same directory as
254 the source file, or, if -o is given, the full path in this name is used.
257 <label id="option--pagelength">
258 <tag><tt>--pagelength n</tt></tag>
260 sets the length of a listing page in lines. See the <tt><ref
261 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
264 <label id="option--relax-checks">
265 <tag><tt>--relax-checks</tt></tag>
267 Relax some checks done by the assembler. This will allow code that is an
268 error in most cases and flagged as such by the assembler, but can be valid
269 in special situations.
273 <item>Short branches between two different segments.
274 <item>Byte sized address loads where the address is not a zeropage address.
278 <label id="option-s">
279 <tag><tt>-s, --smart-mode</tt></tag>
281 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
282 pseudo instruction) the assembler will track usage of the <tt/REP/ and
283 <tt/SEP/ instructions in 65816 mode and update the operand sizes
284 accordingly. If the operand of such an instruction cannot be evaluated by
285 the assembler (for example, because the operand is an imported symbol), a
288 Beware: Since the assembler cannot trace the execution flow this may
289 lead to false results in some cases. If in doubt, use the .ixx and .axx
290 instructions to tell the assembler about the current settings. Smart
291 mode is off by default.
294 <label id="option-t">
295 <tag><tt>-t sys, --target sys</tt></tag>
297 Set the target system. This will enable translation of character strings and
298 character constants into the character set of the target platform. The
299 default for the target system is "none", which means that no translation
300 will take place. The assembler supports the same target systems as the
301 compiler, see there for a list.
303 Depending on the target, the default CPU type is also set. This can be
304 overriden by using the <tt/<ref id="option--cpu" name="--cpu">/ option.
307 <label id="option-v">
308 <tag><tt>-v, --verbose</tt></tag>
310 Increase the assembler verbosity. Usually only needed for debugging
311 purposes. You may use this option more than one time for even more
315 <label id="option-D">
316 <tag><tt>-D</tt></tag>
318 This option allows you to define symbols on the command line. Without a
319 value, the symbol is defined with the value zero. When giving a value,
320 you may use the '$' prefix for hexadecimal symbols. Please note
321 that for some operating systems, '$' has a special meaning, so
322 you may have to quote the expression.
325 <label id="option-I">
326 <tag><tt>-I dir, --include-dir dir</tt></tag>
328 Name a directory which is searched for include files. The option may be
329 used more than once to specify more than one directory to search. The
330 current directory is always searched first before considering any
331 additional directories. See also the section about <ref id="search-paths"
332 name="search paths">.
335 <label id="option-U">
336 <tag><tt>-U, --auto-import</tt></tag>
338 Mark symbols that are not defined in the sources as imported symbols. This
339 should be used with care since it delays error messages about typos and such
340 until the linker is run. The compiler uses the equivalent of this switch
341 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
342 symbols for the runtime library. However, the compiler is supposed to
343 generate code that runs through the assembler without problems, something
344 which is not always true for assembler programmers.
347 <label id="option-V">
348 <tag><tt>-V, --version</tt></tag>
350 Print the version number of the assembler. If you send any suggestions
351 or bugfixes, please include the version number.
354 <label id="option-W">
355 <tag><tt>-Wn</tt></tag>
357 Set the warning level for the assembler. Using -W2 the assembler will
358 even warn about such things like unused imported symbols. The default
359 warning level is 1, and it would probably be silly to set it to
367 <sect>Search paths<label id="search-paths"><p>
369 Normal include files are searched in the following places:
372 <item>The current file's directory.
373 <item>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
375 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
376 <item>A subdirectory named <tt/asminc/ of the directory defined in the
377 environment variable <tt/CC65_HOME/, if it is defined.
378 <item>An optionally compiled-in directory.
381 Binary include files are searched in the following places:
384 <item>The current file's directory.
385 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
386 name="--bin-include-dir">/ option on the command line.
391 <sect>Input format<p>
393 <sect1>Assembler syntax<p>
395 The assembler accepts the standard 6502/65816 assembler syntax. One line may
396 contain a label (which is identified by a colon), and, in addition to the
397 label, an assembler mnemonic, a macro, or a control command (see section <ref
398 id="control-commands" name="Control Commands"> for supported control
399 commands). Alternatively, the line may contain a symbol definition using
400 the '=' token. Everything after a semicolon is handled as a comment (that is,
403 Here are some examples for valid input lines:
406 Label: ; A label and a comment
407 lda #$20 ; A 6502 instruction plus comment
408 L1: ldx #$20 ; Same with label
409 L2: .byte "Hello world" ; Label plus control command
410 mymac $20 ; Macro expansion
411 MySym = 3*L1 ; Symbol definition
412 MaSym = Label ; Another symbol
415 The assembler accepts
418 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
419 <tt><ref id=".P02" name=".P02"></tt> command was given).
420 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
421 <ref id="6502X-mode" name="6502X mode">.
422 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
423 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
424 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
425 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
426 <item>all valid 65816 mnemonics when in 65816 mode (after the
427 <tt><ref id=".P816" name=".P816"></tt> command was given).
428 <item>all valid 4510 mnemonics when in 4510 mode (after the
429 <tt><ref id=".P4510" name=".P4510"></tt> command was given).
435 In 65816 mode, several aliases are accepted, in addition to the official
439 <item><tt>CPA</tt> is an alias for <tt>CMP</tt>
440 <item><tt>DEA</tt> is an alias for <tt>DEC A</tt>
441 <item><tt>INA</tt> is an alias for <tt>INC A</tt>
442 <item><tt>SWA</tt> is an alias for <tt>XBA</tt>
443 <item><tt>TAD</tt> is an alias for <tt>TCD</tt>
444 <item><tt>TAS</tt> is an alias for <tt>TCS</tt>
445 <item><tt>TDA</tt> is an alias for <tt>TDC</tt>
446 <item><tt>TSA</tt> is an alias for <tt>TSC</tt>
450 <sect1>6502X mode<label id="6502X-mode"><p>
452 6502X mode is an extension to the normal 6502 mode. In this mode, several
453 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
454 these instructions are illegal, there are no official mnemonics for them. The
455 unofficial ones are taken from <url
456 url="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
457 ones marked as "stable" are supported. The following table uses information
458 from the mentioned web page, for more information, see there.
461 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
462 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
463 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
464 <item><tt>AXS: X:=A and X-#{imm};</tt>
465 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
466 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
467 <item><tt>LAS: A,X,S:={adr} and S;</tt>
468 <item><tt>LAX: A,X:={adr};</tt>
469 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
470 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
471 <item><tt>SAX: {adr}:=A and X;</tt>
472 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
473 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
479 The 4510 is a microcontroller that is the core of the Commodore C65 aka C64DX.
480 It contains among other functions a slightly modified 65CE02/4502 CPU, to allow
481 address mapping for 20 bits of address space (1 megabyte addressable area).
482 As compared to the description of the CPU in the
483 <url url="http://www.zimmers.net/anonftp/pub/cbm/c65/c65manualupdated.txt.gz"
484 name="C65 System Specification">
485 <url url="https://raw.githubusercontent.com/MEGA65/c65-specifications/master/c65manualupdated.txt"
486 name="(updated version)"> uses these changes:
488 <item><tt>LDA (d,SP),Y</tt> may also be written as <tt>LDA (d,S),Y</tt>
489 (matching the 65816 notataion).
490 <item>All branch instruction allow now 16 bit offsets. To use a 16 bit
491 branch you have to prefix these with an "L" (e.g. "<tt>LBNE</tt>" instead of
492 "<tt>BNE</tt>"). This might change at a later implementation of the assembler.
494 For more information about the Commodore C65/C64DX and the 4510 CPU, see
495 <url url="http://www.zimmers.net/anonftp/pub/cbm/c65/"> and
496 <url url="https://en.wikipedia.org/wiki/Commodore_65" name="Wikipedia">.
499 <sect1>sweet16 mode<label id="sweet16-mode"><p>
501 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
502 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
503 generate code for this pseudo CPU when switched into sweet16 mode. The
504 following is special in sweet16 mode:
508 <item>The '@' character denotes indirect addressing and is no longer available
509 for cheap local labels. If you need cheap local labels, you will have to
510 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
511 name=".LOCALCHAR">/ command.
513 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
514 these identifiers are reserved words.
518 Please note that the assembler does neither supply the interpreter needed for
519 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
520 nor does it call the interpreter. All this must be done by your program. Apple
521 ][ programmers do probably know how to use sweet16 mode.
523 For more information about SWEET 16, see
524 <url url="http://www.6502.org/source/interpreters/sweet16.htm">.
527 <sect1>Number format<p>
529 For literal values, the assembler accepts the widely used number formats: A
530 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
531 denotes a binary value, and a bare number is interpreted as a decimal. There
532 are currently no octal values and no floats.
535 <sect1>Conditional assembly<p>
537 Please note that when using the conditional directives (<tt/.IF/ and friends),
538 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
539 that are not assembled. The reason for this behaviour is that the assembler
540 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
541 conversion of the input stream into tokens still takes place. As a consequence
542 conditional assembly directives may <bf/not/ be used to prevent normal text
543 (used as a comment or similar) from being assembled. <p>
549 <sect1>Expression evaluation<p>
551 All expressions are evaluated with (at least) 32 bit precision. An
552 expression may contain constant values and any combination of internal and
553 external symbols. Expressions that cannot be evaluated at assembly time
554 are stored inside the object file for evaluation by the linker.
555 Expressions referencing imported symbols must always be evaluated by the
559 <sect1>Size of an expression result<p>
561 Sometimes, the assembler must know about the size of the value that is the
562 result of an expression. This is usually the case, if a decision has to be
563 made, to generate a zero page or an absolute memory references. In this
564 case, the assembler has to make some assumptions about the result of an
568 <item> If the result of an expression is constant, the actual value is
569 checked to see if it's a byte sized expression or not.
570 <item> If the expression is explicitly casted to a byte sized expression by
571 one of the '>', '<' or '^' operators, it is a byte expression.
572 <item> If this is not the case, and the expression contains a symbol,
573 explicitly declared as zero page symbol (by one of the .importzp or
574 .exportzp instructions), then the whole expression is assumed to be
576 <item> If the expression contains symbols that are not defined, and these
577 symbols are local symbols, the enclosing scopes are searched for a
578 symbol with the same name. If one exists and this symbol is defined,
579 its attributes are used to determine the result size.
580 <item> In all other cases the expression is assumed to be word sized.
583 Note: If the assembler is not able to evaluate the expression at assembly
584 time, the linker will evaluate it and check for range errors as soon as
588 <sect1>Boolean expressions<p>
590 In the context of a boolean expression, any non zero value is evaluated as
591 true, any other value to false. The result of a boolean expression is 1 if
592 it's true, and zero if it's false. There are boolean operators with extreme
593 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
594 operators are shortcut operators. That is, if the result of the expression is
595 already known, after evaluating the left hand side, the right hand side is
599 <sect1>Constant expressions<p>
601 Sometimes an expression must evaluate to a constant without looking at any
602 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
603 that decides if parts of the code are assembled or not. An expression used in
604 the <tt/.IF/ command cannot reference a symbol defined later, because the
605 decision about the <tt/.IF/ must be made at the point when it is read. If the
606 expression used in such a context contains only constant numerical values,
607 there is no problem. When unresolvable symbols are involved it may get harder
608 for the assembler to determine if the expression is actually constant, and it
609 is even possible to create expressions that aren't recognized as constant.
610 Simplifying the expressions will often help.
612 In cases where the result of the expression is not needed immediately, the
613 assembler will delay evaluation until all input is read, at which point all
614 symbols are known. So using arbitrary complex constant expressions is no
615 problem in most cases.
619 <sect1>Available operators<label id="operators"><p>
623 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
624 | Built-in string functions| 0@
626 | Built-in pseudo-variables| 1@
627 | Built-in pseudo-functions| 1@
628 +| Unary positive| 1@
629 -| Unary negative| 1@
631 .BITNOT| Unary bitwise not| 1@
633 .LOBYTE| Unary low-byte operator| 1@
635 .HIBYTE| Unary high-byte operator| 1@
637 .BANKBYTE| Unary bank-byte operator| 1@
639 *| Multiplication| 2@
641 .MOD| Modulo operator| 2@
643 .BITAND| Bitwise and| 2@
645 .BITXOR| Binary bitwise xor| 2@
647 .SHL| Shift-left operator| 2@
649 .SHR| Shift-right operator| 2@
651 +| Binary addition| 3@
652 -| Binary subtraction| 3@
654 .BITOR| Bitwise or| 3@
656 = | Compare operator (equal)| 4@
657 <>| Compare operator (not equal)| 4@
658 <| Compare operator (less)| 4@
659 >| Compare operator (greater)| 4@
660 <=| Compare operator (less or equal)| 4@
661 >=| Compare operator (greater or equal)| 4@
664 .AND| Boolean and| 5@
665 .XOR| Boolean xor| 5@
667 ||<newline>
671 .NOT| Boolean not| 7@<hline>
673 <caption>Available operators, sorted by precedence
676 To force a specific order of evaluation, parentheses may be used, as usual.
680 <sect>Symbols and labels<p>
682 A symbol or label is an identifier that starts with a letter and is followed
683 by letters and digits. Depending on some features enabled (see
684 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
685 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
686 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
687 other characters may be present. Use of identifiers consisting of a single
688 character will not work in all cases, because some of these identifiers are
689 reserved keywords (for example "A" is not a valid identifier for a label,
690 because it is the keyword for the accumulator).
692 The assembler allows you to use symbols instead of naked values to make
693 the source more readable. There are a lot of different ways to define and
694 use symbols and labels, giving a lot of flexibility.
696 <sect1>Numeric constants<p>
698 Numeric constants are defined using the equal sign or the label assignment
699 operator. After doing
705 may use the symbol "two" in every place where a number is expected, and it is
706 evaluated to the value 2 in this context. The label assignment operator is
707 almost identical, but causes the symbol to be marked as a label, so it may be
708 handled differently in a debugger:
714 The right side can of course be an expression:
721 <label id="variables">
722 <sect1>Numeric variables<p>
724 Within macros and other control structures (<tt><ref id=".REPEAT"
725 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
726 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
727 symbol that may get assigned a different value later:
731 lda #four ; Loads 4 into A
733 lda #four ; Loads 3 into A
736 Since the value of the symbol can change later, it must be possible to
737 evaluate it when used (no delayed evaluation as with normal symbols). So the
738 expression used as the value must be constant.
740 Following is an example for a macro that generates a different label each time
741 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
742 and a numeric variable named <tt>lcount</tt>.
745 .lcount .set 0 ; Initialize the counter
748 .ident (.sprintf ("L%04X", lcount)):
749 lcount .set lcount + 1
754 <sect1>Standard labels<p>
756 A label is defined by writing the name of the label at the start of the line
757 (before any instruction mnemonic, macro or pseudo directive), followed by a
758 colon. This will declare a symbol with the given name and the value of the
759 current program counter.
762 <sect1>Local labels and symbols<p>
764 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
765 create regions of code where the names of labels and symbols are local to this
766 region. They are not known outside of this region and cannot be accessed from
767 there. Such regions may be nested like PROCEDUREs in Pascal.
769 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
770 directive for more information.
773 <sect1>Cheap local labels<p>
775 Cheap local labels are defined like standard labels, but the name of the
776 label must begin with a special symbol (usually '@', but this can be
777 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
780 Cheap local labels are visible only between two non cheap labels. As soon as a
781 standard symbol is encountered (this may also be a local symbol if inside a
782 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
783 cheap local symbol goes out of scope.
785 You may use cheap local labels as an easy way to reuse common label
786 names like "Loop". Here is an example:
789 Clear: lda #$00 ; Global label
791 @Loop: sta Mem,y ; Local label
795 Sub: ... ; New global label
796 bne @Loop ; ERROR: Unknown identifier!
799 <sect1>Unnamed labels<p>
801 If you really want to write messy code, there are also unnamed labels. These
802 labels do not have a name (you guessed that already, didn't you?). A colon is
803 used to mark the absence of the name.
805 Unnamed labels may be accessed by using the colon plus several minus or plus
806 characters as a label designator. Using the '-' characters will create a back
807 reference (use the n'th label backwards), using '+' will create a forward
808 reference (use the n'th label in forward direction). An example will help to
831 As you can see from the example, unnamed labels will make even short
832 sections of code hard to understand, because you have to count labels
833 to find branch targets (this is the reason why I for my part do
834 prefer the "cheap" local labels). Nevertheless, unnamed labels are
835 convenient in some situations, so it's your decision.
837 <em/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
838 unnamed ones, so scopes don't have an effect on unnamed labels.
842 <sect1>Using macros to define labels and constants<p>
844 While there are drawbacks with this approach, it may be handy in a few rare
845 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
846 to define symbols or constants that may be used elsewhere. One of the
847 advantages is that you can use it to define string constants (this is not
848 possible with the other symbol types).
850 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
851 so the names do not adhere to scoping, diagnostics may be misleading, there
852 are no symbols to look up in the map file, and there is no debug info.
853 Especially the first problem in the list can lead to very nasty programming
854 errors. Because of these problems, the general advice is, <bf/NOT/ do use
855 <tt/.DEFINE/ if you don't have to.
861 .DEFINE version "SOS V2.3"
863 four = two * two ; Ok
866 .PROC ; Start local scope
867 two = 3 ; Will give "2 = 3" - invalid!
872 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
874 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
875 id="option-g" name="-g"> is given on the command line), global, local and
876 cheap local labels are written to the object file and will be available in the
877 symbol file via the linker. Unnamed labels are not written to the object file,
878 because they don't have a name which would allow to access them.
882 <sect>Scopes<label id="scopes"><p>
884 ca65 implements several sorts of scopes for symbols.
886 <sect1>Global scope<p>
888 All (non cheap local) symbols that are declared outside of any nested scopes
892 <sect1>Cheap locals<p>
894 A special scope is the scope for cheap local symbols. It lasts from one non
895 local symbol to the next one, without any provisions made by the programmer.
896 All other scopes differ in usage but use the same concept internally.
899 <sect1>Generic nested scopes<p>
901 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
902 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
903 The scope can have a name, in which case it is accessible from the outside by
904 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
905 have a name, all symbols created within the scope are local to the scope, and
906 aren't accessible from the outside.
908 A nested scope can access symbols from the local or from enclosing scopes by
909 name without using explicit scope names. In some cases there may be
910 ambiguities, for example if there is a reference to a local symbol that is not
911 yet defined, but a symbol with the same name exists in outer scopes:
923 In the example above, the <tt/lda/ instruction will load the value 3 into the
924 accumulator, because <tt/foo/ is redefined in the scope. However:
936 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
937 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
938 absolute mode is used instead. In fact, the assembler will not use absolute
939 mode by default, but it will search through the enclosing scopes for a symbol
940 with the given name. If one is found, the address size of this symbol is used.
941 This may lead to errors:
953 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
954 instruction, it will search for an already defined symbol <tt/foo/. It will
955 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
956 zeropage symbol. So the assembler will use zeropage addressing mode. If
957 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
958 the address in the <tt/lda/ instruction already translated, but since the new
959 value needs absolute addressing mode, this fails, and an error message "Range
962 Of course the most simple solution for the problem is to move the definition
963 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
964 rare cases when this cannot be done. In these cases, you can use one of the
965 address size override operators:
977 This will cause the <tt/lda/ instruction to be translated using absolute
978 addressing mode, which means changing the symbol reference later does not
982 <sect1>Nested procedures<p>
984 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
985 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
986 name, and a it will introduce a symbol with this name in the enclosing scope.
995 is actually the same as
1004 This is the reason why a procedure must have a name. If you want a scope
1005 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
1007 <em/Note:/ As you can see from the example above, scopes and symbols live in
1008 different namespaces. There can be a symbol named <tt/foo/ and a scope named
1009 <tt/foo/ without any conflicts (but see the section titled <ref
1010 id="scopesearch" name=""Scope search order"">).
1013 <sect1>Structs, unions and enums<p>
1015 Structs, unions and enums are explained in a <ref id="structs" name="separate
1016 section">, I do only cover them here, because if they are declared with a
1017 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
1018 name=".SCOPE">/. However, when no name is specified, the behaviour is
1019 different: In this case, no new scope will be opened, symbols declared within
1020 a struct, union, or enum declaration will then be added to the enclosing scope
1024 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1026 Accessing symbols from other scopes is possible by using an explicit scope
1027 specification, provided that the scope where the symbol lives in has a name.
1028 The namespace token (<tt/::/) is used to access other scopes:
1036 lda foo::bar ; Access foo in scope bar
1039 The only way to deny access to a scope from the outside is to declare a scope
1040 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1042 A special syntax is used to specify the global scope: If a symbol or scope is
1043 preceded by the namespace token, the global scope is searched:
1050 lda #::bar ; Access the global bar (which is 3)
1055 <sect1>Scope search order<label id="scopesearch"><p>
1057 The assembler searches for a scope in a similar way as for a symbol. First, it
1058 looks in the current scope, and then it walks up the enclosing scopes until
1061 However, one important thing to note when using explicit scope syntax is, that
1062 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1063 used without a preceding definition. This means that in the following
1072 lda #foo::bar ; Will load 3, not 2!
1079 the reference to the scope <tt/foo/ will use the global scope, and not the
1080 local one, because the local one is not visible at the point where it is
1083 Things get more complex if a complete chain of scopes is specified:
1094 lda #outer::inner::bar ; 1
1106 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1107 assembler will first search in the local scope for a scope named <tt/outer/.
1108 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1109 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1110 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1111 this scope, the assembler looks for a symbol named <tt/bar/.
1113 Please note that once the anchor scope is found, all following scopes
1114 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1115 assembler will search the scope tree only for the first scope (if it is not
1116 anchored in the root scope). Starting from there on, there is no flexibility,
1117 so if the scope named <tt/outer/ found by the assembler does not contain a
1118 scope named <tt/inner/, this would be an error, even if such a pair does exist
1119 (one level up in global scope).
1121 Ambiguities that may be introduced by this search algorithm may be removed by
1122 anchoring the scope specification in the global scope. In the example above,
1123 if you want to access the "other" symbol <tt/bar/, you would have to write:
1134 lda #::outer::inner::bar ; 2
1147 <sect>Address sizes and memory models<label id="address-sizes"><p>
1149 <sect1>Address sizes<p>
1151 ca65 assigns each segment and each symbol an address size. This is true, even
1152 if the symbol is not used as an address. You may also think of a value range
1153 of the symbol instead of an address size.
1155 Possible address sizes are:
1158 <item>Zeropage or direct (8 bits)
1159 <item>Absolute (16 bits)
1161 <item>Long (32 bits)
1164 Since the assembler uses default address sizes for the segments and symbols,
1165 it is usually not necessary to override the default behaviour. In cases, where
1166 it is necessary, the following keywords may be used to specify address sizes:
1169 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1170 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1171 <item>FAR for far addressing (24 bits).
1172 <item>LONG or DWORD for long addressing (32 bits).
1176 <sect1>Address sizes of segments<p>
1178 The assembler assigns an address size to each segment. Since the
1179 representation of a label within this segment is "segment start + offset",
1180 labels will inherit the address size of the segment they are declared in.
1182 The address size of a segment may be changed, by using an optional address
1183 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1184 an explanation on how this is done.
1187 <sect1>Address sizes of symbols<p>
1192 <sect1>Memory models<p>
1194 The default address size of a segment depends on the memory model used. Since
1195 labels inherit the address size from the segment they are declared in,
1196 changing the memory model is an easy way to change the address size of many
1202 <sect>Pseudo variables<label id="pseudo-variables"><p>
1204 Pseudo variables are readable in all cases, and in some special cases also
1207 <sect1><tt>*</tt><p>
1209 Reading this pseudo variable will return the program counter at the start
1210 of the current input line.
1212 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1213 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1214 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1217 <sect1><tt>.ASIZE</tt><label id=".ASIZE"><p>
1219 Reading this pseudo variable will return the current size of the
1220 Accumulator in bits.
1222 For the 65816 instruction set .ASIZE will return either 8 or 16, depending
1223 on the current size of the operand in immediate accu addressing mode.
1225 For all other CPU instruction sets, .ASIZE will always return 8.
1230 ; Reverse Subtract with Accumulator
1243 See also: <tt><ref id=".ISIZE" name=".ISIZE"></tt>
1246 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1248 Reading this pseudo variable will give a constant integer value that
1249 tells which CPU is currently enabled. It can also tell which instruction
1250 set the CPU is able to translate. The value read from the pseudo variable
1251 should be further examined by using one of the constants defined by the
1252 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1254 It may be used to replace the .IFPxx pseudo instructions or to construct
1255 even more complex expressions.
1261 .if (.cpu .bitand CPU_ISET_65816)
1273 <sect1><tt>.ISIZE</tt><label id=".ISIZE"><p>
1275 Reading this pseudo variable will return the current size of the Index
1278 For the 65816 instruction set .ISIZE will return either 8 or 16, depending
1279 on the current size of the operand in immediate index addressing mode.
1281 For all other CPU instruction sets, .ISIZE will always return 8.
1283 See also: <tt><ref id=".ASIZE" name=".ASIZE"></tt>
1286 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1288 This builtin pseudo variable is only available in macros. It is replaced by
1289 the actual number of parameters that were given in the macro invocation.
1294 .macro foo arg1, arg2, arg3
1295 .if .paramcount <> 3
1296 .error "Too few parameters for macro foo"
1302 See section <ref id="macros" name="Macros">.
1305 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1307 Reading this pseudo variable will give a constant integer value that
1308 represents the current time in POSIX standard (as seconds since the
1311 It may be used to encode the time of translation somewhere in the created
1317 .dword .time ; Place time here
1321 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1323 Reading this pseudo variable will give the assembler version according to
1324 the following formula:
1326 VER_MAJOR*$100 + VER_MINOR*$10
1328 It may be used to encode the assembler version or check the assembler for
1329 special features not available with older versions.
1333 Version 2.14 of the assembler will return $2E0 as numerical constant when
1334 reading the pseudo variable <tt/.VERSION/.
1338 <sect>Pseudo functions<label id="pseudo-functions"><p>
1340 Pseudo functions expect their arguments in parenthesis, and they have a result,
1341 either a string or an expression.
1344 <sect1><tt>.ADDRSIZE</tt><label id=".ADDRSIZE"><p>
1346 The <tt/.ADDRSIZE/ function is used to return the interal address size
1347 associated with a symbol. This can be helpful in macros when knowing the address
1348 size of symbol can help with custom instructions.
1354 .if .ADDRSIZE(foo) = 1
1355 ;do custom command based on zeropage addressing:
1357 .elseif .ADDRSIZE(foo) = 2
1358 ;do custom command based on absolute addressing:
1361 .elseif .ADDRSIZE(foo) = 0
1362 ; no address size defined for this symbol:
1363 .out .sprintf("Error, address size unknown for symbol %s", .string(foo))
1368 This command is new and must be enabled with the <tt/.FEATURE addrsize/ command.
1370 See: <tt><ref id=".FEATURE" name=".FEATURE"></tt>
1373 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1375 The <tt/.BANK/ function is used to support systems with banked memory. The
1376 argument is an expression with exactly one segment reference - usually a
1377 label. The function result is the value of the <tt/bank/ attribute assigned
1378 to the run memory area of the segment. Please see the linker documentation
1379 for more information about memory areas and their attributes.
1381 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1382 containing specific data is available.
1384 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1385 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1386 name=".LOBYTE"></tt> or similar functions to address just part of it.
1388 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1389 an expression containing <tt/.BANK/ can never be used where a constant known
1390 result is expected (for example with <tt/.RES/).
1407 .byte <.BANK (banked_func_1)
1410 .byte <.BANK (banked_func_2)
1416 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1418 The function returns the bank byte (that is, bits 16-23) of its argument.
1419 It works identical to the '^' operator.
1421 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1422 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1425 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1427 Builtin function. The function evaluates its argument in braces and yields
1428 "false" if the argument is non blank (there is an argument), and "true" if
1429 there is no argument. The token list that makes up the function argument
1430 may optionally be enclosed in curly braces. This allows the inclusion of
1431 tokens that would otherwise terminate the list (the closing right
1432 parenthesis). The curly braces are not considered part of the list, a list
1433 just consisting of curly braces is considered to be empty.
1435 As an example, the <tt/.IFBLANK/ statement may be replaced by
1443 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1445 Builtin string function. The function allows to concatenate a list of string
1446 constants separated by commas. The result is a string constant that is the
1447 concatenation of all arguments. This function is most useful in macros and
1448 when used together with the <tt/.STRING/ builtin function. The function may
1449 be used in any case where a string constant is expected.
1454 .include .concat ("myheader", ".", "inc")
1457 This is the same as the command
1460 .include "myheader.inc"
1464 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1466 Builtin function. The function evaluates its argument in braces and
1467 yields "true" if the argument is a constant expression (that is, an
1468 expression that yields a constant value at assembly time) and "false"
1469 otherwise. As an example, the .IFCONST statement may be replaced by
1476 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1478 The function returns the high byte (that is, bits 8-15) of its argument.
1479 It works identical to the '>' operator.
1481 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1482 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1485 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1487 The function returns the high word (that is, bits 16-31) of its argument.
1489 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1492 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1494 The function expects a string as its argument, and converts this argument
1495 into an identifier. If the string starts with the current <tt/<ref
1496 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1497 identifier, otherwise it will be converted into a normal identifier.
1502 .macro makelabel arg1, arg2
1503 .ident (.concat (arg1, arg2)):
1506 makelabel "foo", "bar"
1508 .word foobar ; Valid label
1512 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1514 Builtin function. Extracts the left part of a given token list.
1519 .LEFT (<int expr>, <token list>)
1522 The first integer expression gives the number of tokens to extract from
1523 the token list. The second argument is the token list itself. The token
1524 list may optionally be enclosed into curly braces. This allows the
1525 inclusion of tokens that would otherwise terminate the list (the closing
1526 right paren in the given case).
1530 To check in a macro if the given argument has a '#' as first token
1531 (immediate addressing mode), use something like this:
1536 .if (.match (.left (1, {arg}), #))
1538 ; ldax called with immediate operand
1546 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1547 name=".RIGHT"></tt> builtin functions.
1550 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1552 The function returns the low byte (that is, bits 0-7) of its argument.
1553 It works identical to the '<' operator.
1555 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1556 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1559 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1561 The function returns the low word (that is, bits 0-15) of its argument.
1563 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1566 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1568 Builtin function. Matches two token lists against each other. This is
1569 most useful within macros, since macros are not stored as strings, but
1575 .MATCH(<token list #1>, <token list #2>)
1578 Both token list may contain arbitrary tokens with the exception of the
1579 terminator token (comma resp. right parenthesis) and
1586 The token lists may optionally be enclosed into curly braces. This allows
1587 the inclusion of tokens that would otherwise terminate the list (the closing
1588 right paren in the given case). Often a macro parameter is used for any of
1591 Please note that the function does only compare tokens, not token
1592 attributes. So any number is equal to any other number, regardless of the
1593 actual value. The same is true for strings. If you need to compare tokens
1594 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1595 name=".XMATCH"></tt> function.
1599 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1600 while honoring the sign bit. The builtin processor instructions will allow
1601 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1602 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1603 to check for this and print and error for invalid calls.
1608 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1609 .error "Syntax error"
1612 cmp #$80 ; Bit 7 into carry
1613 lsr a ; Shift carry into bit 7
1618 The macro will only accept no arguments, or one argument that must be the
1619 reserved keyword "A".
1621 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1624 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1626 Builtin function. The result is the larger of two values.
1631 .MAX (<value #1>, <value #2>)
1637 ; Reserve space for the larger of two data blocks
1638 savearea: .res .max (.sizeof (foo), .sizeof (bar))
1641 See: <tt><ref id=".MIN" name=".MIN"></tt>
1644 <sect1><tt>.MID</tt><label id=".MID"><p>
1646 Builtin function. Takes a starting index, a count and a token list as
1647 arguments. Will return part of the token list.
1652 .MID (<int expr>, <int expr>, <token list>)
1655 The first integer expression gives the starting token in the list (the first
1656 token has index 0). The second integer expression gives the number of tokens
1657 to extract from the token list. The third argument is the token list itself.
1658 The token list may optionally be enclosed into curly braces. This allows the
1659 inclusion of tokens that would otherwise terminate the list (the closing
1660 right paren in the given case).
1664 To check in a macro if the given argument has a '<tt/#/' as first token
1665 (immediate addressing mode), use something like this:
1670 .if (.match (.mid (0, 1, {arg}), #))
1672 ; ldax called with immediate operand
1680 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1681 name=".RIGHT"></tt> builtin functions.
1684 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1686 Builtin function. The result is the smaller of two values.
1691 .MIN (<value #1>, <value #2>)
1697 ; Reserve space for some data, but 256 bytes maximum
1698 savearea: .res .min (.sizeof (foo), 256)
1701 See: <tt><ref id=".MAX" name=".MAX"></tt>
1704 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1706 Builtin function. The function expects an identifier as argument in braces.
1707 The argument is evaluated, and the function yields "true" if the identifier
1708 is a symbol that has already been referenced somewhere in the source file up
1709 to the current position. Otherwise the function yields false. As an example,
1710 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1716 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1719 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1721 Builtin function. Extracts the right part of a given token list.
1726 .RIGHT (<int expr>, <token list>)
1729 The first integer expression gives the number of tokens to extract from the
1730 token list. The second argument is the token list itself. The token list
1731 may optionally be enclosed into curly braces. This allows the inclusion of
1732 tokens that would otherwise terminate the list (the closing right paren in
1735 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1736 name=".MID"></tt> builtin functions.
1739 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1741 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1742 argument can be a struct/union, a struct member, a procedure, or a label. In
1743 case of a procedure or label, its size is defined by the amount of data
1744 placed in the segment where the label is relative to. If a line of code
1745 switches segments (for example in a macro) data placed in other segments
1746 does not count for the size.
1748 Please note that a symbol or scope must exist, before it is used together with
1749 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1750 A scope has preference over a symbol with the same name, so if the last part
1751 of a name represents both, a scope and a symbol, the scope is chosen over the
1754 After the following code:
1757 .struct Point ; Struct size = 4
1762 P: .tag Point ; Declare a point
1763 @P: .tag Point ; Declare another point
1775 .data ; Segment switch!!!
1781 <tag><tt/.sizeof(Point)/</tag>
1782 will have the value 4, because this is the size of struct <tt/Point/.
1784 <tag><tt/.sizeof(Point::xcoord)/</tag>
1785 will have the value 2, because this is the size of the member <tt/xcoord/
1786 in struct <tt/Point/.
1788 <tag><tt/.sizeof(P)/</tag>
1789 will have the value 4, this is the size of the data declared on the same
1790 source line as the label <tt/P/, which is in the same segment that <tt/P/
1793 <tag><tt/.sizeof(@P)/</tag>
1794 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1795 does also work for cheap local symbols.
1797 <tag><tt/.sizeof(Code)/</tag>
1798 will have the value 3, since this is amount of data emitted into the code
1799 segment, the segment that was active when <tt/Code/ was entered. Note that
1800 this value includes the amount of data emitted in child scopes (in this
1801 case <tt/Code::Inner/).
1803 <tag><tt/.sizeof(Code::Inner)/</tag>
1804 will have the value 1 as expected.
1806 <tag><tt/.sizeof(Data)/</tag>
1807 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1808 the segment is switched after entry, this data is emitted into another
1813 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1815 Builtin function. The function accepts a string and an index as
1816 arguments and returns the value of the character at the given position
1817 as an integer value. The index is zero based.
1823 ; Check if the argument string starts with '#'
1824 .if (.strat (Arg, 0) = '#')
1831 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1833 Builtin function. It expects a format string as first argument. The number
1834 and type of the following arguments depend on the format string. The format
1835 string is similar to the one of the C <tt/printf/ function. Missing things
1836 are: Length modifiers, variable width.
1838 The result of the function is a string.
1845 ; Generate an identifier:
1846 .ident (.sprintf ("%s%03d", "label", num)):
1850 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1852 Builtin function. The function accepts an argument in braces and converts
1853 this argument into a string constant. The argument may be an identifier, or
1854 a constant numeric value.
1856 Since you can use a string in the first place, the use of the function may
1857 not be obvious. However, it is useful in macros, or more complex setups.
1862 ; Emulate other assemblers:
1864 .segment .string(name)
1869 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1871 Builtin function. The function accepts a string argument in braces and
1872 evaluates to the length of the string.
1876 The following macro encodes a string as a pascal style string with
1877 a leading length byte.
1881 .byte .strlen(Arg), Arg
1886 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1888 Builtin function. The function accepts a token list in braces. The function
1889 result is the number of tokens given as argument. The token list may
1890 optionally be enclosed into curly braces which are not considered part of
1891 the list and not counted. Enclosement in curly braces allows the inclusion
1892 of tokens that would otherwise terminate the list (the closing right paren
1897 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1898 with the normal 6502 instructions). To translate it into two separate 8 bit
1899 load instructions, the '#' token has to get stripped from the argument:
1903 .if (.match (.mid (0, 1, {arg}), #))
1904 ; ldax called with immediate operand
1905 lda #<(.right (.tcount ({arg})-1, {arg}))
1906 ldx #>(.right (.tcount ({arg})-1, {arg}))
1914 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1916 Builtin function. Matches two token lists against each other. This is
1917 most useful within macros, since macros are not stored as strings, but
1923 .XMATCH(<token list #1>, <token list #2>)
1926 Both token list may contain arbitrary tokens with the exception of the
1927 terminator token (comma resp. right parenthesis) and
1934 The token lists may optionally be enclosed into curly braces. This allows
1935 the inclusion of tokens that would otherwise terminate the list (the closing
1936 right paren in the given case). Often a macro parameter is used for any of
1939 The function compares tokens <em/and/ token values. If you need a function
1940 that just compares the type of tokens, have a look at the <tt><ref
1941 id=".MATCH" name=".MATCH"></tt> function.
1943 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1947 <sect>Control commands<label id="control-commands"><p>
1949 Here's a list of all control commands and a description, what they do:
1952 <sect1><tt>.A16</tt><label id=".A16"><p>
1954 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1956 Note: This command will not emit any code, it will tell the assembler to
1957 create 16 bit operands for immediate accumulator addressing mode.
1959 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1962 <sect1><tt>.A8</tt><label id=".A8"><p>
1964 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1966 Note: This command will not emit any code, it will tell the assembler to
1967 create 8 bit operands for immediate accu addressing mode.
1969 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1972 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1974 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1975 may be used for better readability if the data words are address values. In
1976 65816 mode, the address is forced to be 16 bit wide to fit into the current
1977 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1978 must be followed by a sequence of (not necessarily constant) expressions.
1983 .addr $0D00, $AF13, _Clear
1986 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1990 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1992 Align data to a given boundary. The command expects a constant integer
1993 argument in the range 1 ... 65536, plus an optional second argument
1994 in byte range. If there is a second argument, it is used as fill value,
1995 otherwise the value defined in the linker configuration file is used
1996 (the default for this value is zero).
1998 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1999 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
2000 number of bytes, since that would break address calculations within the
2001 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
2002 of the alignment, because that allows the number of fill bytes to be
2003 calculated in advance by the assembler. You are therefore required to
2004 specify a matching alignment for the segment in the linker config. The
2005 linker will output a warning if the alignment of the segment is less than
2006 what is necessary to have a correct alignment in the object file.
2014 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
2015 commands with different arguments. To allow the assembler to calculate the
2016 number of fill bytes in advance, the alignment of the segment must be a
2017 multiple of each of the alignment factors. This may result in unexpectedly
2018 large alignments for the segment within the module.
2029 For the assembler to be able to align correctly, the segment must be aligned
2030 to the least common multiple of 15 and 18 which is 90. The assembler will
2031 calculate this automatically and will mark the segment with this value.
2033 Unfortunately, the combined alignment may get rather large without the user
2034 knowing about it, wasting space in the final executable. If we add another
2035 alignment to the example above
2046 the assembler will force a segment alignment to the least common multiple of
2047 15, 18 and 251 - which is 22590. To protect the user against errors, the
2048 assembler will issue a warning when the combined alignment exceeds 256. The
2049 command line option <tt><ref id="option--large-alignment"
2050 name="--large-alignment"></tt> will disable this warning.
2052 Please note that with alignments that are a power of two (which were the
2053 only alignments possible in older versions of the assembler), the problem is
2054 less severe, because the least common multiple of powers to the same base is
2055 always the larger one.
2059 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
2061 Define a string with a trailing zero.
2066 Msg: .asciiz "Hello world"
2069 This will put the string "Hello world" followed by a binary zero into
2070 the current segment. There may be more strings separated by commas, but
2071 the binary zero is only appended once (after the last one).
2074 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2076 Add an assertion. The command is followed by an expression, an action
2077 specifier, and an optional message that is output in case the assertion
2078 fails. If no message was given, the string "Assertion failed" is used. The
2079 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2080 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2081 assembler if possible, and in any case, it's also passed to the linker in
2082 the object file (if one is generated). The linker will then evaluate the
2083 expression when segment placement has been done.
2088 .assert * = $8000, error, "Code not at $8000"
2091 The example assertion will check that the current location is at $8000,
2092 when the output file is written, and abort with an error if this is not
2093 the case. More complex expressions are possible. The action specifier
2094 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2095 an error message. In the latter case, generation of the output file is
2096 suppressed in both the assembler and linker.
2099 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2101 Is followed by a plus or a minus character. When switched on (using a
2102 +), undefined symbols are automatically marked as import instead of
2103 giving errors. When switched off (which is the default so this does not
2104 make much sense), this does not happen and an error message is
2105 displayed. The state of the autoimport flag is evaluated when the
2106 complete source was translated, before outputting actual code, so it is
2107 <em/not/ possible to switch this feature on or off for separate sections
2108 of code. The last setting is used for all symbols.
2110 You should probably not use this switch because it delays error
2111 messages about undefined symbols until the link stage. The cc65
2112 compiler (which is supposed to produce correct assembler code in all
2113 circumstances, something which is not true for most assembler
2114 programmers) will insert this command to avoid importing each and every
2115 routine from the runtime library.
2120 .autoimport + ; Switch on auto import
2123 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2125 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2126 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2127 the operator '^' prepended to each expression in its list.
2132 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2134 TableLookupLo: .lobytes MyTable
2135 TableLookupHi: .hibytes MyTable
2136 TableLookupBank: .bankbytes MyTable
2139 which is equivalent to
2142 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2143 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2144 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2147 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2148 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2149 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2152 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2154 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2155 so this is a shortcut for
2161 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2164 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2166 Define byte sized data. Must be followed by a sequence of (byte ranged)
2167 expressions or strings.
2173 .byt "world", $0D, $00
2177 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2179 Switch on or off case sensitivity on identifiers. The default is off
2180 (that is, identifiers are case sensitive), but may be changed by the
2181 -i switch on the command line.
2182 The command must be followed by a '+' or '-' character to switch the
2183 option on or off respectively.
2188 .case - ; Identifiers are not case sensitive
2192 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2194 Apply a custom mapping for characters. The command is followed by two
2195 numbers. The first one is the index of the source character (range 0..255);
2196 the second one is the mapping (range 0..255). The mapping applies to all
2197 character and string constants <em/when/ they generate output; and, overrides
2198 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2199 command line switch.
2203 .charmap $41, $61 ; Map 'A' to 'a'
2207 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2209 Switch to the CODE segment. The name of the CODE segment is always
2210 "CODE", so this is a shortcut for
2216 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2219 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2221 Export a symbol and mark it in a special way. The linker is able to build
2222 tables of all such symbols. This may be used to automatically create a list
2223 of functions needed to initialize linked library modules.
2225 Note: The linker has a feature to build a table of marked routines, but it
2226 is your code that must call these routines, so just declaring a symbol with
2227 <tt/.CONDES/ does nothing by itself.
2229 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2230 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2231 is implied by <tt/.CONDES/.
2233 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2234 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2235 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2236 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2237 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2238 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2239 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2241 After the type, an optional priority may be specified. Higher numeric values
2242 mean higher priority. If no priority is given, the default priority of 7 is
2243 used. Be careful when assigning priorities to your own module constructors
2244 so they won't interfere with the ones in the cc65 library.
2249 .condes ModuleInit, constructor
2250 .condes ModInit, 0, 16
2253 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2254 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2255 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2256 name="Module constructors/destructors"> explaining the feature in more
2260 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2262 Export a symbol and mark it as a module constructor. This may be used
2263 together with the linker to build a table of constructor subroutines that
2264 are called by the startup code.
2266 Note: The linker has a feature to build a table of marked routines, but it
2267 is your code that must call these routines, so just declaring a symbol as
2268 constructor does nothing by itself.
2270 A constructor is always exported as an absolute (16 bit) symbol. You don't
2271 need to use an additional <tt/.export/ statement, this is implied by
2272 <tt/.constructor/. It may have an optional priority that is separated by a
2273 comma. Higher numeric values mean a higher priority. If no priority is
2274 given, the default priority of 7 is used. Be careful when assigning
2275 priorities to your own module constructors so they won't interfere with the
2276 ones in the cc65 library.
2281 .constructor ModuleInit
2282 .constructor ModInit, 16
2285 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2286 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2287 <ref id="condes" name="Module constructors/destructors"> explaining the
2288 feature in more detail.
2291 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2293 Switch to the DATA segment. The name of the DATA segment is always
2294 "DATA", so this is a shortcut for
2300 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2303 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2305 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2306 create word sized data in native 65XX format). Must be followed by a
2307 sequence of (word ranged) expressions.
2315 This will emit the bytes
2321 into the current segment in that order.
2324 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2326 Switch on or off debug info generation. The default is off (that is,
2327 the object file will not contain debug infos), but may be changed by the
2328 -g switch on the command line.
2329 The command must be followed by a '+' or '-' character to switch the
2330 option on or off respectively.
2335 .debuginfo + ; Generate debug info
2339 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2341 Start a define style macro definition. The command is followed by an
2342 identifier (the macro name) and optionally by a list of formal arguments
2345 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2346 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2349 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2350 section <ref id="macros" name="Macros">.
2353 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2355 Delete a classic macro (defined with <tt><ref id=".MACRO"
2356 name=".MACRO"></tt>) . The command is followed by the name of an
2357 existing macro. Its definition will be deleted together with the name.
2358 If necessary, another macro with this name may be defined later.
2360 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2361 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2362 <tt><ref id=".MACRO" name=".MACRO"></tt>
2364 See also section <ref id="macros" name="Macros">.
2367 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2369 Builtin function. The function expects an identifier as argument in braces.
2370 The argument is evaluated, and the function yields "true" if the identifier
2371 is a symbol that is already defined somewhere in the source file up to the
2372 current position. Otherwise the function yields false. As an example, the
2373 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2380 <sect1><tt>.DEFINEDMACRO</tt><label id=".DEFINEDMACRO"><p>
2382 Builtin function. The function expects an identifier as argument in braces.
2383 The argument is evaluated, and the function yields "true" if the identifier
2384 has already been defined as the name of a macro. Otherwise the function yields
2393 .if .definedmacro(add)
2402 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2404 Export a symbol and mark it as a module destructor. This may be used
2405 together with the linker to build a table of destructor subroutines that
2406 are called by the startup code.
2408 Note: The linker has a feature to build a table of marked routines, but it
2409 is your code that must call these routines, so just declaring a symbol as
2410 constructor does nothing by itself.
2412 A destructor is always exported as an absolute (16 bit) symbol. You don't
2413 need to use an additional <tt/.export/ statement, this is implied by
2414 <tt/.destructor/. It may have an optional priority that is separated by a
2415 comma. Higher numerical values mean a higher priority. If no priority is
2416 given, the default priority of 7 is used. Be careful when assigning
2417 priorities to your own module destructors so they won't interfere with the
2418 ones in the cc65 library.
2423 .destructor ModuleDone
2424 .destructor ModDone, 16
2427 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2428 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2429 section <ref id="condes" name="Module constructors/destructors"> explaining
2430 the feature in more detail.
2433 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2435 Define dword sized data (4 bytes) Must be followed by a sequence of
2441 .dword $12344512, $12FA489
2445 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2447 Conditional assembly: Reverse the current condition.
2450 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2452 Conditional assembly: Reverse current condition and test a new one.
2455 <sect1><tt>.END</tt><label id=".END"><p>
2457 Forced end of assembly. Assembly stops at this point, even if the command
2458 is read from an include file.
2461 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2463 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2466 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2468 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2469 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2472 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2474 Marks the end of a macro definition.
2476 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2477 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2478 <tt><ref id=".MACRO" name=".MACRO"></tt>
2480 See also section <ref id="macros" name="Macros">.
2483 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2485 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2488 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2490 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2493 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2495 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2498 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2500 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2501 command and the separate section named <ref id="structs" name=""Structs
2505 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2507 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2508 command and the separate section named <ref id="structs" name=""Structs
2512 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2514 Start an enumeration. This directive is very similar to the C <tt/enum/
2515 keyword. If a name is given, a new scope is created for the enumeration,
2516 otherwise the enumeration members are placed in the enclosing scope.
2518 In the enumeration body, symbols are declared. The first symbol has a value
2519 of zero, and each following symbol will get the value of the preceding plus
2520 one. This behaviour may be overridden by an explicit assignment. Two symbols
2521 may have the same value.
2533 Above example will create a new scope named <tt/errorcodes/ with three
2534 symbols in it that get the values 0, 1 and 2 respectively. Another way
2535 to write this would have been:
2545 Please note that explicit scoping must be used to access the identifiers:
2548 .word errorcodes::no_error
2551 A more complex example:
2560 EWOULDBLOCK = EAGAIN
2564 In this example, the enumeration does not have a name, which means that the
2565 members will be visible in the enclosing scope and can be used in this scope
2566 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2567 The value for the following members is incremented by one, so <tt/EOK/ would
2568 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2569 override for the value using an already defined symbol.
2572 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2574 Force an assembly error. The assembler will output an error message
2575 preceded by "User error". Assembly is continued but no object file will
2578 This command may be used to check for initial conditions that must be
2579 set before assembling a source file.
2589 .error "Must define foo or bar!"
2593 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2594 <tt><ref id=".OUT" name=".OUT"></tt>,
2595 <tt><ref id=".WARNING" name=".WARNING"></tt>
2598 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2600 Abort a macro expansion immediately. This command is often useful in
2603 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2604 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2605 <tt><ref id=".MACRO" name=".MACRO"></tt>
2607 See also section <ref id="macros" name="Macros">.
2610 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2612 Make symbols accessible from other modules. Must be followed by a comma
2613 separated list of symbols to export, with each one optionally followed by an
2614 address specification and (also optional) an assignment. Using an additional
2615 assignment in the export statement allows to define and export a symbol in
2616 one statement. The default is to export the symbol with the address size it
2617 actually has. The assembler will issue a warning, if the symbol is exported
2618 with an address size smaller than the actual address size.
2625 .export foobar: far = foo * bar
2626 .export baz := foobar, zap: far = baz - bar
2629 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2632 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2635 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2637 Make symbols accessible from other modules. Must be followed by a comma
2638 separated list of symbols to export. The exported symbols are explicitly
2639 marked as zero page symbols. An assignment may be included in the
2640 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2647 .exportzp baz := $02
2650 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2653 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2655 Define far (24 bit) address data. The command must be followed by a
2656 sequence of (not necessarily constant) expressions.
2661 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2664 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2667 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2669 Force an assembly error and terminate assembly. The assembler will output an
2670 error message preceded by "User error" and will terminate assembly
2673 This command may be used to check for initial conditions that must be
2674 set before assembling a source file.
2684 .fatal "Must define foo or bar!"
2688 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2689 <tt><ref id=".OUT" name=".OUT"></tt>,
2690 <tt><ref id=".WARNING" name=".WARNING"></tt>
2693 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2695 This directive may be used to enable one or more compatibility features
2696 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2697 possible, it may be useful when porting sources written for other
2698 assemblers. There is no way to switch a feature off, once you have
2699 enabled it, so using
2705 will enable the feature until end of assembly is reached.
2707 The following features are available:
2711 <tag><tt>addrsize</tt><label id="addrsize"></tag>
2713 Enables the .ADDRSIZE pseudo function. This function is experimental and not enabled by default.
2715 See also: <tt><ref id=".ADDRSIZE" name=".ADDRSIZE"></tt>
2717 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2719 Accept the at character (`@') as a valid character in identifiers. The
2720 at character is not allowed to start an identifier, even with this
2723 <tag><tt>bracket_as_indirect</tt><label id="bracket_as_indirect"></tag>
2725 Use <tt>[]</tt> instead of <tt>()</tt> for the indirect addressing modes.
2735 <em/Note:/ This should not be used in 65186 mode because it conflicts with
2736 the 65816 instruction syntax for far addressing. See the section covering
2737 <tt/<ref id="address-sizes" name="address sizes">/ for more information.
2739 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2741 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2742 comment terminators. Note that C comments may not be nested. There's also a
2743 pitfall when using C like comments: All statements must be terminated by
2744 "end-of-line". Using C like comments, it is possible to hide the newline,
2745 which results in error messages. See the following non working example:
2748 lda #$00 /* This comment hides the newline
2752 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2754 Accept the dollar sign (`$') as a valid character in identifiers. The
2755 dollar character is not allowed to start an identifier, even with this
2758 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2760 The dollar sign may be used as an alias for the star (`*'), which
2761 gives the value of the current PC in expressions.
2762 Note: Assignment to the pseudo variable is not allowed.
2764 <tag><tt>force_range</tt><label id="force_range"></tag>
2766 Force expressions into their valid range for immediate addressing and
2767 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2768 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2769 since it will completely disable error checks.
2771 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2773 Allow labels without a trailing colon. These labels are only accepted,
2774 if they start at the beginning of a line (no leading white space).
2776 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2778 Accept the dot (`.') as the first character of an identifier. This may be
2779 used for example to create macro names that start with a dot emulating
2780 control directives of other assemblers. Note however, that none of the
2781 reserved keywords built into the assembler, that starts with a dot, may be
2782 overridden. When using this feature, you may also get into trouble if
2783 later versions of the assembler define new keywords starting with a dot.
2785 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2787 Accept single quotes as well as double quotes as terminators for char
2790 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2792 Accept single quotes as well as double quotes as terminators for string
2795 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2797 Accept single quoted character constants where the terminating quote is
2802 <em/Note:/ This does not work in conjunction with <tt/.FEATURE
2803 loose_string_term/, since in this case the input would be ambiguous.
2805 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2807 This feature makes relocatable/absolute mode local to the current segment.
2808 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2809 effect will only enable absolute mode for the current segment. Dito for
2810 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2812 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2814 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2815 is enabled). Such an assignment is handled identical to the <tt><ref
2816 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2817 removing the lines with the assignments may also be an option when porting
2818 code written for older assemblers).
2820 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2822 Allow the use of instructions names as names for macros and symbols. This
2823 makes it possible to "overload" instructions by defining a macro with the
2824 same name. This does also make it possible to introduce hard to find errors
2825 in your code, so be careful!
2827 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2829 Allow underlines within numeric constants. These may be used for grouping
2830 the digits of numbers for easier reading.
2833 .feature underline_in_numbers
2834 .word %1100001110100101
2835 .word %1100_0011_1010_0101 ; Identical but easier to read
2840 It is also possible to specify features on the command line using the
2841 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2842 This is useful when translating sources written for older assemblers, when
2843 you don't want to change the source code.
2845 As an example, to translate sources written for Andre Fachats xa65
2846 assembler, the features
2849 labels_without_colons, pc_assignment, loose_char_term
2852 may be helpful. They do not make ca65 completely compatible, so you may not
2853 be able to translate the sources without changes, even when enabling these
2854 features. However, I have found several sources that translate without
2855 problems when enabling these features on the command line.
2858 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2860 Insert an option string into the object file. There are two forms of
2861 this command, one specifies the option by a keyword, the second
2862 specifies it as a number. Since usage of the second one needs knowledge
2863 of the internal encoding, its use is not recommended and I will only
2864 describe the first form here.
2866 The command is followed by one of the keywords
2874 a comma and a string. The option is written into the object file
2875 together with the string value. This is currently unidirectional and
2876 there is no way to actually use these options once they are in the
2882 .fileopt comment, "Code stolen from my brother"
2883 .fileopt compiler, "BASIC 2.0"
2884 .fopt author, "J. R. User"
2888 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2890 Import an absolute symbol from another module. The command is followed by a
2891 comma separated list of symbols to import. The command is similar to <tt>
2892 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2893 written to the generated object file, even if the symbol is never referenced
2894 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2895 references for unused symbols).
2900 .forceimport needthisone, needthistoo
2903 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2906 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2908 Declare symbols as global. Must be followed by a comma separated list of
2909 symbols to declare. Symbols from the list, that are defined somewhere in the
2910 source, are exported, all others are imported. Additional <tt><ref
2911 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2912 name=".EXPORT"></tt> commands for the same symbol are allowed.
2921 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2923 Declare symbols as global. Must be followed by a comma separated list of
2924 symbols to declare. Symbols from the list, that are defined somewhere in the
2925 source, are exported, all others are imported. Additional <tt><ref
2926 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2927 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2928 in the list are explicitly marked as zero page symbols.
2936 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2938 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2939 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2940 the operator '>' prepended to each expression in its list.
2945 .lobytes $1234, $2345, $3456, $4567
2946 .hibytes $fedc, $edcb, $dcba, $cba9
2949 which is equivalent to
2952 .byte $34, $45, $56, $67
2953 .byte $fe, $ed, $dc, $cb
2959 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2961 TableLookupLo: .lobytes MyTable
2962 TableLookupHi: .hibytes MyTable
2965 which is equivalent to
2968 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2969 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2972 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2973 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2974 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2977 <sect1><tt>.I16</tt><label id=".I16"><p>
2979 Valid only in 65816 mode. Switch the index registers to 16 bit.
2981 Note: This command will not emit any code, it will tell the assembler to
2982 create 16 bit operands for immediate operands.
2984 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2985 name=".SMART"></tt> commands.
2988 <sect1><tt>.I8</tt><label id=".I8"><p>
2990 Valid only in 65816 mode. Switch the index registers to 8 bit.
2992 Note: This command will not emit any code, it will tell the assembler to
2993 create 8 bit operands for immediate operands.
2995 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2996 name=".SMART"></tt> commands.
2999 <sect1><tt>.IF</tt><label id=".IF"><p>
3001 Conditional assembly: Evaluate an expression and switch assembler output
3002 on or off depending on the expression. The expression must be a constant
3003 expression, that is, all operands must be defined.
3005 A expression value of zero evaluates to FALSE, any other value evaluates
3009 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
3011 Conditional assembly: Check if there are any remaining tokens in this line,
3012 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
3013 condition is not true, further lines are not assembled until an <tt><ref
3014 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3015 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3017 This command is often used to check if a macro parameter was given. Since an
3018 empty macro parameter will evaluate to nothing, the condition will evaluate
3019 to TRUE if an empty parameter was given.
3033 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3036 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
3038 Conditional assembly: Evaluate an expression and switch assembler output
3039 on or off depending on the constness of the expression.
3041 A const expression evaluates to to TRUE, a non const expression (one
3042 containing an imported or currently undefined symbol) evaluates to
3045 See also: <tt><ref id=".CONST" name=".CONST"></tt>
3048 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
3050 Conditional assembly: Check if a symbol is defined. Must be followed by
3051 a symbol name. The condition is true if the the given symbol is already
3052 defined, and false otherwise.
3054 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3057 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
3059 Conditional assembly: Check if there are any remaining tokens in this line,
3060 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
3061 condition is not true, further lines are not assembled until an <tt><ref
3062 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3063 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3065 This command is often used to check if a macro parameter was given.
3066 Since an empty macro parameter will evaluate to nothing, the condition
3067 will evaluate to FALSE if an empty parameter was given.
3080 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3083 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
3085 Conditional assembly: Check if a symbol is defined. Must be followed by
3086 a symbol name. The condition is true if the the given symbol is not
3087 defined, and false otherwise.
3089 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3092 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
3094 Conditional assembly: Check if a symbol is referenced. Must be followed
3095 by a symbol name. The condition is true if if the the given symbol was
3096 not referenced before, and false otherwise.
3098 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3101 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
3103 Conditional assembly: Check if the assembler is currently in 6502 mode
3104 (see <tt><ref id=".P02" name=".P02"></tt> command).
3107 <sect1><tt>.IFP4510</tt><label id=".IFP4510"><p>
3109 Conditional assembly: Check if the assembler is currently in 4510 mode
3110 (see <tt><ref id=".P4510" name=".P4510"></tt> command).
3113 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
3115 Conditional assembly: Check if the assembler is currently in 65816 mode
3116 (see <tt><ref id=".P816" name=".P816"></tt> command).
3119 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
3121 Conditional assembly: Check if the assembler is currently in 65C02 mode
3122 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3125 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3127 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3128 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3131 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3133 Conditional assembly: Check if a symbol is referenced. Must be followed
3134 by a symbol name. The condition is true if if the the given symbol was
3135 referenced before, and false otherwise.
3137 This command may be used to build subroutine libraries in include files
3138 (you may use separate object modules for this purpose too).
3143 .ifref ToHex ; If someone used this subroutine
3144 ToHex: tay ; Define subroutine
3150 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3153 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3155 Import a symbol from another module. The command is followed by a comma
3156 separated list of symbols to import, with each one optionally followed by
3157 an address specification.
3163 .import bar: zeropage
3166 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3169 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3171 Import a symbol from another module. The command is followed by a comma
3172 separated list of symbols to import. The symbols are explicitly imported
3173 as zero page symbols (that is, symbols with values in byte range).
3181 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3184 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3186 Include a file as binary data. The command expects a string argument
3187 that is the name of a file to include literally in the current segment.
3188 In addition to that, a start offset and a size value may be specified,
3189 separated by commas. If no size is specified, all of the file from the
3190 start offset to end-of-file is used. If no start position is specified
3191 either, zero is assumed (which means that the whole file is inserted).
3196 ; Include whole file
3197 .incbin "sprites.dat"
3199 ; Include file starting at offset 256
3200 .incbin "music.dat", $100
3202 ; Read 100 bytes starting at offset 200
3203 .incbin "graphics.dat", 200, 100
3207 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3209 Include another file. Include files may be nested up to a depth of 16.
3218 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3220 Export a symbol and mark it as an interruptor. This may be used together
3221 with the linker to build a table of interruptor subroutines that are called
3224 Note: The linker has a feature to build a table of marked routines, but it
3225 is your code that must call these routines, so just declaring a symbol as
3226 interruptor does nothing by itself.
3228 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3229 need to use an additional <tt/.export/ statement, this is implied by
3230 <tt/.interruptor/. It may have an optional priority that is separated by a
3231 comma. Higher numeric values mean a higher priority. If no priority is
3232 given, the default priority of 7 is used. Be careful when assigning
3233 priorities to your own module constructors so they won't interfere with the
3234 ones in the cc65 library.
3239 .interruptor IrqHandler
3240 .interruptor Handler, 16
3243 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3244 section <ref id="condes" name="Module constructors/destructors"> explaining
3245 the feature in more detail.
3248 <sect1><tt>.ISMNEM, .ISMNEMONIC</tt><label id=".ISMNEMONIC"><p>
3250 Builtin function. The function expects an identifier as argument in braces.
3251 The argument is evaluated, and the function yields "true" if the identifier
3252 is defined as an instruction mnemonic that is recognized by the assembler.
3256 .if .not .ismnemonic(ina)
3265 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3267 Switch on or off line continuations using the backslash character
3268 before a newline. The option is off by default.
3269 Note: Line continuations do not work in a comment. A backslash at the
3270 end of a comment is treated as part of the comment and does not trigger
3272 The command must be followed by a '+' or '-' character to switch the
3273 option on or off respectively.
3278 .linecont + ; Allow line continuations
3281 #$20 ; This is legal now
3285 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3287 Enable output to the listing. The command must be followed by a boolean
3288 switch ("on", "off", "+" or "-") and will enable or disable listing
3290 The option has no effect if the listing is not enabled by the command line
3291 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3292 to the listing file, if the counter is greater than zero, and suppressed if
3293 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3299 .list on ; Enable listing output
3303 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3305 Set, how many bytes are shown in the listing for one source line. The
3306 default is 12, so the listing will show only the first 12 bytes for any
3307 source line that generates more than 12 bytes of code or data.
3308 The directive needs an argument, which is either "unlimited", or an
3309 integer constant in the range 4..255.
3314 .listbytes unlimited ; List all bytes
3315 .listbytes 12 ; List the first 12 bytes
3316 .incbin "data.bin" ; Include large binary file
3320 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3322 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3323 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3324 the operator '<' prepended to each expression in its list.
3329 .lobytes $1234, $2345, $3456, $4567
3330 .hibytes $fedc, $edcb, $dcba, $cba9
3333 which is equivalent to
3336 .byte $34, $45, $56, $67
3337 .byte $fe, $ed, $dc, $cb
3343 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3345 TableLookupLo: .lobytes MyTable
3346 TableLookupHi: .hibytes MyTable
3349 which is equivalent to
3352 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3353 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3356 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3357 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3358 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3361 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3363 This command may only be used inside a macro definition. It declares a
3364 list of identifiers as local to the macro expansion.
3366 A problem when using macros are labels: Since they don't change their name,
3367 you get a "duplicate symbol" error if the macro is expanded the second time.
3368 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3369 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3372 Some other assemblers start a new lexical block inside a macro expansion.
3373 This has some drawbacks however, since that will not allow <em/any/ symbol
3374 to be visible outside a macro, a feature that is sometimes useful. The
3375 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3376 to address the problem.
3378 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3382 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3384 Defines the character that start "cheap" local labels. You may use one
3385 of '@' and '?' as start character. The default is '@'.
3387 Cheap local labels are labels that are visible only between two non
3388 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3389 using explicit lexical nesting.
3396 Clear: lda #$00 ; Global label
3397 ?Loop: sta Mem,y ; Local label
3401 Sub: ... ; New global label
3402 bne ?Loop ; ERROR: Unknown identifier!
3406 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3408 Insert a predefined macro package. The command is followed by an
3409 identifier specifying the macro package to insert. Available macro
3413 atari Defines the scrcode macro.
3414 cbm Defines the scrcode macro.
3415 cpu Defines constants for the .CPU variable.
3416 generic Defines generic macroes like add, sub, and blt.
3417 longbranch Defines conditional long-jump macroes.
3420 Including a macro package twice, or including a macro package that
3421 redefines already existing macros will lead to an error.
3426 .macpack longbranch ; Include macro package
3428 cmp #$20 ; Set condition codes
3429 jne Label ; Jump long on condition
3432 Macro packages are explained in more detail in section <ref
3433 id="macropackages" name="Macro packages">.
3436 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3438 Start a classic macro definition. The command is followed by an identifier
3439 (the macro name) and optionally by a comma separated list of identifiers
3440 that are macro parameters. A macro definition is terminated by <tt><ref
3441 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3446 .macro ldax arg ; Define macro ldax
3451 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3452 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3453 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3455 See also section <ref id="macros" name="Macros">.
3458 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3460 Start a section of absolute code. The command is followed by a constant
3461 expression that gives the new PC counter location for which the code is
3462 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3465 By default, absolute/relocatable mode is global (valid even when switching
3466 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3467 it can be made segment local.
3469 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3470 code at a specific address is the job of the linker, not the assembler, so
3471 there is usually no reason to assemble code to a specific address.
3476 .org $7FF ; Emit code starting at $7FF
3480 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3482 Output a string to the console without producing an error. This command
3483 is similar to <tt/.ERROR/, however, it does not force an assembler error
3484 that prevents the creation of an object file.
3489 .out "This code was written by the codebuster(tm)"
3492 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3493 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3494 <tt><ref id=".WARNING" name=".WARNING"></tt>
3497 <sect1><tt>.P02</tt><label id=".P02"><p>
3499 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3500 instructions. This is the default if not overridden by the
3501 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3503 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3504 name=".PSC02"></tt>, <tt><ref id=".P816" name=".P816"></tt> and
3505 <tt><ref id=".P4510" name=".P4510"></tt>
3508 <sect1><tt>.P4510</tt><label id=".P4510"><p>
3510 Enable the 4510 instruction set. This is a superset of the 65C02 and
3511 6502 instruction sets.
3513 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3514 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt> and
3515 <tt><ref id=".P816" name=".P816"></tt>
3518 <sect1><tt>.P816</tt><label id=".P816"><p>
3520 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3521 6502 instruction sets.
3523 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3524 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt> and
3525 <tt><ref id=".P4510" name=".P4510"></tt>
3528 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3530 Set the page length for the listing. Must be followed by an integer
3531 constant. The value may be "unlimited", or in the range 32 to 127. The
3532 statement has no effect if no listing is generated. The default value is -1
3533 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3534 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3535 after assembly is complete, you cannot use multiple line lengths with one
3536 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3541 .pagelength 66 ; Use 66 lines per listing page
3543 .pagelength unlimited ; Unlimited page length
3547 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3549 Enable the 65C02 instructions set. This instruction set includes all
3550 6502 and 65SC02 instructions.
3552 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3553 name=".PSC02"></tt>, <tt><ref id=".P816" name=".P816"></tt> and
3554 <tt><ref id=".P4510" name=".P4510"></tt>
3557 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3559 Pop the last CPU setting from the stack, and activate it.
3561 This command will switch back to the CPU that was last pushed onto the CPU
3562 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3563 remove this entry from the stack.
3565 The assembler will print an error message if the CPU stack is empty when
3566 this command is issued.
3568 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3569 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3572 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3574 Pop the last pushed segment from the stack, and set it.
3576 This command will switch back to the segment that was last pushed onto the
3577 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3578 command, and remove this entry from the stack.
3580 The assembler will print an error message if the segment stack is empty
3581 when this command is issued.
3583 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3586 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3588 Start a nested lexical level with the given name and adds a symbol with this
3589 name to the enclosing scope. All new symbols from now on are in the local
3590 lexical level and are accessible from outside only via <ref id="scopesyntax"
3591 name="explicit scope specification">. Symbols defined outside this local
3592 level may be accessed as long as their names are not used for new symbols
3593 inside the level. Symbols names in other lexical levels do not clash, so you
3594 may use the same names for identifiers. The lexical level ends when the
3595 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3596 may be nested up to a depth of 16 (this is an artificial limit to protect
3597 against errors in the source).
3599 Note: Macro names are always in the global level and in a separate name
3600 space. There is no special reason for this, it's just that I've never
3601 had any need for local macro definitions.
3606 .proc Clear ; Define Clear subroutine, start new level
3608 L1: sta Mem,y ; L1 is local and does not cause a
3609 ; duplicate symbol error if used in other
3612 bne L1 ; Reference local symbol
3614 .endproc ; Leave lexical level
3617 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3621 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3623 Enable the 65SC02 instructions set. This instruction set includes all
3626 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3627 name=".PC02"></tt>, <tt><ref id=".P816" name=".P816"></tt> and
3628 <tt><ref id=".P4510" name=".P4510"></tt>
3631 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3633 Push the currently active CPU onto a stack. The stack has a size of 8
3636 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3637 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3638 later, without knowledge of the current CPU setting.
3640 The assembler will print an error message if the CPU stack is already full,
3641 when this command is issued.
3643 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3644 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3647 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3649 Push the currently active segment onto a stack. The entries on the stack
3650 include the name of the segment and the segment type. The stack has a size
3653 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3654 to switch to another segment and to restore the old segment later, without
3655 even knowing the name and type of the current segment.
3657 The assembler will print an error message if the segment stack is already
3658 full, when this command is issued.
3660 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3663 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3665 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3666 name=".ORG"></tt> command.
3669 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3671 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3672 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3673 a constant expression that tells how many times the commands in the body
3674 should get repeated. Optionally, a comma and an identifier may be specified.
3675 If this identifier is found in the body of the repeat statement, it is
3676 replaced by the current repeat count (starting with zero for the first time
3677 the body is repeated).
3679 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3680 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3681 level will be used, not the one from the outer level.
3685 The following macro will emit a string that is "encrypted" in that all
3686 characters of the string are XORed by the value $55.
3690 .repeat .strlen(Arg), I
3691 .byte .strat(Arg, I) ^ $55
3696 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3699 <sect1><tt>.RES</tt><label id=".RES"><p>
3701 Reserve storage. The command is followed by one or two constant
3702 expressions. The first one is mandatory and defines, how many bytes of
3703 storage should be defined. The second, optional expression must by a
3704 constant byte value that will be used as value of the data. If there
3705 is no fill value given, the linker will use the value defined in the
3706 linker configuration file (default: zero).
3711 ; Reserve 12 bytes of memory with value $AA
3716 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3718 Switch to the RODATA segment. The name of the RODATA segment is always
3719 "RODATA", so this is a shortcut for
3725 The RODATA segment is a segment that is used by the compiler for
3726 readonly data like string constants.
3728 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3731 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3733 Start a nested lexical level with the given name. All new symbols from now
3734 on are in the local lexical level and are accessible from outside only via
3735 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3736 outside this local level may be accessed as long as their names are not used
3737 for new symbols inside the level. Symbols names in other lexical levels do
3738 not clash, so you may use the same names for identifiers. The lexical level
3739 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3740 read. Lexical levels may be nested up to a depth of 16 (this is an
3741 artificial limit to protect against errors in the source).
3743 Note: Macro names are always in the global level and in a separate name
3744 space. There is no special reason for this, it's just that I've never
3745 had any need for local macro definitions.
3750 .scope Error ; Start new scope named Error
3752 File = 1 ; File error
3753 Parse = 2 ; Parse error
3754 .endscope ; Close lexical level
3757 lda #Error::File ; Use symbol from scope Error
3760 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3764 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3766 Switch to another segment. Code and data is always emitted into a
3767 segment, that is, a named section of data. The default segment is
3768 "CODE". There may be up to 254 different segments per object file
3769 (and up to 65534 per executable). There are shortcut commands for
3770 the most common segments ("ZEROPAGE", "CODE", "RODATA", "DATA", and "BSS").
3772 The command is followed by a string containing the segment name (there are
3773 some constraints for the name - as a rule of thumb use only those segment
3774 names that would also be valid identifiers). There may also be an optional
3775 address size separated by a colon. See the section covering <tt/<ref
3776 id="address-sizes" name="address sizes">/ for more information.
3778 The default address size for a segment depends on the memory model specified
3779 on the command line. The default is "absolute", which means that you don't
3780 have to use an address size modifier in most cases.
3782 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3783 That is, the segment will reside somewhere in core memory outside the zero
3784 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3785 page and direct (short) addressing is possible for data in this segment.
3787 Beware: Only labels in a segment with the zeropage attribute are marked
3788 as reachable by short addressing. The `*' (PC counter) operator will
3789 work as in other segments and will create absolute variable values.
3791 Please note that a segment cannot have two different address sizes. A
3792 segment specified as zeropage cannot be declared as being absolute later.
3797 .segment "ROM2" ; Switch to ROM2 segment
3798 .segment "ZP2": zeropage ; New direct segment
3799 .segment "ZP2" ; Ok, will use last attribute
3800 .segment "ZP2": absolute ; Error, redecl mismatch
3803 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3804 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt>, <tt><ref
3805 id=".RODATA" name=".RODATA"></tt>, and <tt><ref id=".ZEROPAGE"
3806 name=".ZEROPAGE"></tt>
3809 <sect1><tt>.SET</tt><label id=".SET"><p>
3811 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3812 name="Numeric variables"> for a full description.
3815 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3817 Switch the CPU instruction set. The command is followed by a string that
3818 specifies the CPU. Possible values are those that can also be supplied to
3819 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3820 namely: 6502, 6502X, 65SC02, 65C02, 65816, 4510 and HuC6280.
3822 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3823 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3824 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3825 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3826 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3827 <tt><ref id=".P02" name=".P02"></tt>,
3828 <tt><ref id=".P816" name=".P816"></tt>,
3829 <tt><ref id=".P4510" name=".P4510"></tt>,
3830 <tt><ref id=".PC02" name=".PC02"></tt>,
3831 <tt><ref id=".PSC02" name=".PSC02"></tt>
3834 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3836 Switch on or off smart mode. The command must be followed by a '+' or '-'
3837 character to switch the option on or off respectively. The default is off
3838 (that is, the assembler doesn't try to be smart), but this default may be
3839 changed by the -s switch on the command line.
3841 In smart mode the assembler will do the following:
3844 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3845 and update the operand sizes accordingly. If the operand of such an
3846 instruction cannot be evaluated by the assembler (for example, because
3847 the operand is an imported symbol), a warning is issued. Beware: Since
3848 the assembler cannot trace the execution flow this may lead to false
3849 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3850 instructions to tell the assembler about the current settings.
3851 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3852 used within a procedure declared as <tt/far/, or if the procedure has
3853 no explicit address specification, but it is <tt/far/ because of the
3861 .smart - ; Stop being smart
3864 See: <tt><ref id=".A16" name=".A16"></tt>,
3865 <tt><ref id=".A8" name=".A8"></tt>,
3866 <tt><ref id=".I16" name=".I16"></tt>,
3867 <tt><ref id=".I8" name=".I8"></tt>
3870 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3872 Starts a struct definition. Structs are covered in a separate section named
3873 <ref id="structs" name=""Structs and unions"">.
3875 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3876 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3877 <tt><ref id=".UNION" name=".UNION"></tt>
3880 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3882 Allocate space for a struct or union.
3893 .tag Point ; Allocate 4 bytes
3897 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3899 Delete a define style macro definition. The command is followed by an
3900 identifier which specifies the name of the macro to delete. Macro
3901 replacement is switched of when reading the token following the command
3902 (otherwise the macro name would be replaced by its replacement list).
3904 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3905 section <ref id="macros" name="Macros">.
3908 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3910 Starts a union definition. Unions are covered in a separate section named
3911 <ref id="structs" name=""Structs and unions"">.
3913 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3914 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3915 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3918 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3920 Force an assembly warning. The assembler will output a warning message
3921 preceded by "User warning". This warning will always be output, even if
3922 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3923 command line option.
3925 This command may be used to output possible problems when assembling
3934 .warning "Forward jump in jne, cannot optimize!"
3944 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3945 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3946 <tt><ref id=".OUT" name=".OUT"></tt>
3949 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3951 Define word sized data. Must be followed by a sequence of (word ranged,
3952 but not necessarily constant) expressions.
3957 .word $0D00, $AF13, _Clear
3961 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3963 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3964 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3968 .segment "ZEROPAGE": zeropage
3971 Because of the "zeropage" attribute, labels declared in this segment are
3972 addressed using direct addressing mode if possible. You <em/must/ instruct
3973 the linker to place this segment somewhere in the address range 0..$FF
3974 otherwise you will get errors.
3976 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3980 <sect>Macros<label id="macros"><p>
3983 <sect1>Introduction<p>
3985 Macros may be thought of as "parametrized super instructions". Macros are
3986 sequences of tokens that have a name. If that name is used in the source
3987 file, the macro is "expanded", that is, it is replaced by the tokens that
3988 were specified when the macro was defined.
3991 <sect1>Macros without parameters<p>
3993 In its simplest form, a macro does not have parameters. Here's an
3997 .macro asr ; Arithmetic shift right
3998 cmp #$80 ; Put bit 7 into carry
3999 ror ; Rotate right with carry
4003 The macro above consists of two real instructions, that are inserted into
4004 the code, whenever the macro is expanded. Macro expansion is simply done
4005 by using the name, like this:
4014 <sect1>Parametrized macros<p>
4016 When using macro parameters, macros can be even more useful:
4030 When calling the macro, you may give a parameter, and each occurrence of
4031 the name "addr" in the macro definition will be replaced by the given
4050 A macro may have more than one parameter, in this case, the parameters
4051 are separated by commas. You are free to give less parameters than the
4052 macro actually takes in the definition. You may also leave intermediate
4053 parameters empty. Empty parameters are replaced by empty space (that is,
4054 they are removed when the macro is expanded). If you have a look at our
4055 macro definition above, you will see, that replacing the "addr" parameter
4056 by nothing will lead to wrong code in most lines. To help you, writing
4057 macros with a variable parameter list, there are some control commands:
4059 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
4060 returns true, if there are any tokens on the remainder of the line. Since
4061 empty parameters are replaced by nothing, this may be used to test if a given
4062 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
4065 Look at this example:
4068 .macro ldaxy a, x, y
4081 That macro may be called as follows:
4084 ldaxy 1, 2, 3 ; Load all three registers
4086 ldaxy 1, , 3 ; Load only a and y
4088 ldaxy , , 3 ; Load y only
4091 There's another helper command for determining which macro parameters are
4092 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>. That command is
4093 replaced by the parameter count given, <em/including/ explicitly empty
4097 ldaxy 1 ; .PARAMCOUNT = 1
4098 ldaxy 1,,3 ; .PARAMCOUNT = 3
4099 ldaxy 1,2 ; .PARAMCOUNT = 2
4100 ldaxy 1, ; .PARAMCOUNT = 2
4101 ldaxy 1,2,3 ; .PARAMCOUNT = 3
4104 Macro parameters may optionally be enclosed into curly braces. This allows the
4105 inclusion of tokens that would otherwise terminate the parameter (the comma in
4106 case of a macro parameter).
4109 .macro foo arg1, arg2
4113 foo ($00,x) ; Two parameters passed
4114 foo {($00,x)} ; One parameter passed
4117 In the first case, the macro is called with two parameters: '<tt/($00/'
4118 and '<tt/x)/'. The comma is not passed to the macro, because it is part of the
4119 calling sequence, not the parameters.
4121 In the second case, '<tt/($00,x)/' is passed to the macro; this time,
4122 including the comma.
4125 <sect1>Detecting parameter types<p>
4127 Sometimes it is nice to write a macro that acts differently depending on the
4128 type of the argument supplied. An example would be a macro that loads a 16 bit
4129 value from either an immediate operand, or from memory. The <tt/<ref
4130 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
4131 functions will allow you to do exactly this:
4135 .if (.match (.left (1, {arg}), #))
4137 lda #<(.right (.tcount ({arg})-1, {arg}))
4138 ldx #>(.right (.tcount ({arg})-1, {arg}))
4140 ; assume absolute or zero page
4147 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4148 check if its argument begins with a hash mark. If so, two immediate loads are
4149 emitted, Otherwise a load from an absolute zero page memory location is
4150 assumed. Please note how the curly braces are used to enclose parameters to
4151 pseudo functions handling token lists. This is necessary, because the token
4152 lists may include commas or parens, which would be treated by the assembler
4155 The macro can be used as
4160 ldax #$1234 ; X=$12, A=$34
4162 ldax foo ; X=$56, A=$78
4166 <sect1>Recursive macros<p>
4168 Macros may be used recursively:
4171 .macro push r1, r2, r3
4180 There's also a special macro command to help with writing recursive macros:
4181 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>. That command will stop macro
4182 expansion immediately:
4185 .macro push r1, r2, r3, r4, r5, r6, r7
4187 ; First parameter is empty
4193 push r2, r3, r4, r5, r6, r7
4197 When expanding that macro, the expansion will push all given parameters
4198 until an empty one is encountered. The macro may be called like this:
4201 push $20, $21, $32 ; Push 3 ZP locations
4202 push $21 ; Push one ZP location
4206 <sect1>Local symbols inside macros<p>
4208 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4209 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4210 Have a look at the inc16 macro above. Here is it again:
4224 If you have a closer look at the code, you will notice, that it could be
4225 written more efficiently, like this:
4236 But imagine what happens, if you use this macro twice? Since the label "Skip"
4237 has the same name both times, you get a "duplicate symbol" error. Without a
4238 way to circumvent this problem, macros are not as useful, as they could be.
4239 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4240 It declares one or more symbols as local to the macro expansion. The names of
4241 local variables are replaced by a unique name in each separate macro
4242 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4246 .local Skip ; Make Skip a local symbol
4250 Skip: ; Not visible outside
4254 Another solution is of course to start a new lexical block inside the macro
4255 that hides any labels:
4269 <sect1>C style macros<p>
4271 Starting with version 2.5 of the assembler, there is a second macro type
4272 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4273 similar to the classic macro type described above, but behaviour is sometimes
4278 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4279 span more than a line. You may use line continuation (see <tt><ref
4280 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4281 more than one line for increased readability, but the macro itself
4282 may not contain an end-of-line token.
4284 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4285 the name space with classic macros, but they are detected and replaced
4286 at the scanner level. While classic macros may be used in every place,
4287 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4288 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4289 they are more versatile in some situations.
4291 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4292 parameters. While classic macros may have empty parameters, this is
4293 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4294 For this macro type, the number of actual parameters must match
4295 exactly the number of formal parameters.
4297 To make this possible, formal parameters are enclosed in braces when
4298 defining the macro. If there are no parameters, the empty braces may
4301 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4302 contain end-of-line tokens, there are things that cannot be done. They
4303 may not contain several processor instructions for example. So, while
4304 some things may be done with both macro types, each type has special
4305 usages. The types complement each other.
4307 <item> Parentheses work differently from C macros.
4308 The common practice of wrapping C macros in parentheses may cause
4309 unintended problems here, such as accidentally implying an
4310 indirect addressing mode. While the definition of a macro requires
4311 parentheses around its argument list, when invoked they should not be
4316 Let's look at a few examples to make the advantages and disadvantages
4319 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4320 following <tt/.DEFINE/:
4325 foo EQU $1234 ; This is accepted now
4328 You may use the directive to define string constants used elsewhere:
4331 ; Define the version number
4332 .define VERSION "12.3a"
4338 Macros with parameters may also be useful:
4341 .define DEBUG(message) .out message
4343 DEBUG "Assembling include file #3"
4346 Note that, while formal parameters have to be placed in parentheses,
4347 the actual argument used when invoking the macro should not be.
4348 The invoked arguments are separated by commas only, if parentheses are
4349 used by accident they will become part of the replaced token.
4351 If you wish to have an expression follow the macro invocation, the
4352 last parameter can be enclosed in curly braces {} to indicate the end of that
4358 .define COMBINE(ta,tb,tc) ta+tb*10+tc*100
4360 .word COMBINE 5,6,7 ; 5+6*10+7*100 = 765
4361 .word COMBINE(5,6,7) ; (5+6*10+7)*100 = 7200 ; incorrect use of parentheses
4362 .word COMBINE 5,6,7+1 ; 5+6*10+7+1*100 = 172
4363 .word COMBINE 5,6,{7}+1 ; 5+6*10+7*100+1 = 766 ; {} encloses the argument
4364 .word COMBINE 5,6-2,7 ; 5+6-2*10+7*100 = 691
4365 .word COMBINE 5,(6-2),7 ; 5+(6-2)*10+7*100 = 745
4366 .word COMBINE 5,6,7+COMBINE 0,1,2 ; 5+6*10+7+0+1*10+2*100*100 = 20082
4367 .word COMBINE 5,6,{7}+COMBINE 0,1,2 ; 5+6*10+7*100+0+1*10+2*100 = 975
4370 With C macros it is common to enclose the results in parentheses to
4371 prevent unintended interactions with the text of the arguments, but
4372 additional care must be taken in this assembly context where parentheses
4373 may alter the meaning of a statement. In particular, indirect addressing modes
4374 may be accidentally implied:
4377 .define DUO(ta,tb) (ta+(tb*10))
4379 lda DUO(5,4), Y ; LDA (indirect), Y
4380 lda 0+DUO(5,4), Y ; LDA absolute indexed, Y
4384 <sect1>Characters in macros<p>
4386 When using the <ref id="option-t" name="-t"> option, characters are translated
4387 into the target character set of the specific machine. However, this happens
4388 as late as possible. This means that strings are translated if they are part
4389 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4390 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4391 used as part of an expression.
4393 This behaviour is very intuitive outside of macros but may be confusing when
4394 doing more complex macros. If you compare characters against numeric values,
4395 be sure to take the translation into account.
4398 <sect1>Deleting macros<p>
4400 Macros can be deleted. This will not work if the macro that should be deleted
4401 is currently expanded as in the following non-working example:
4405 .delmacro notworking
4408 notworking ; Will not work
4411 The commands to delete classic and define style macros differ. Classic macros
4412 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4413 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4414 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4422 .byte value ; Emit one byte with value 1
4423 mac ; Emit another byte with value 2
4428 .byte value ; Error: Unknown identifier
4429 mac ; Error: Missing ":"
4432 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4433 the name of such a macro is replaced by its replacement list on a very low
4434 level. To get the actual name, macro replacement has to be switched off when
4435 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4436 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4437 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4438 different commands increases flexibility.
4442 <sect>Macro packages<label id="macropackages"><p>
4444 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4445 macro packages may be included with just one command. Available macro packages
4449 <sect1><tt>.MACPACK generic</tt><p>
4451 This macro package defines macroes that are useful in almost any program.
4452 Currently defined macroes are:
4455 .macro add Arg ; add without carry
4460 .macro sub Arg ; subtract without borrow
4465 .macro bge Arg ; branch on greater-than or equal
4469 .macro blt Arg ; branch on less-than
4473 .macro bgt Arg ; branch on greater-than
4480 .macro ble Arg ; branch on less-than or equal
4485 .macro bnz Arg ; branch on not zero
4489 .macro bze Arg ; branch on zero
4495 <sect1><tt>.MACPACK longbranch</tt><p>
4497 This macro package defines long conditional jumps. They are named like the
4498 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4499 definition for the "<tt/jeq/" macro, the other macros are built using the same
4504 .if .def(Target) .and ((*+2)-(Target) <= 127)
4513 All macros expand to a short branch, if the label is already defined (back
4514 jump) and is reachable with a short jump. Otherwise the macro expands to a
4515 conditional branch with the branch condition inverted, followed by an absolute
4516 jump to the actual branch target.
4518 The package defines the following macros:
4521 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4526 <sect1><tt>.MACPACK apple2</tt><p>
4528 This macro package defines a macro named <tt/scrcode/. It takes a string
4529 as argument and places this string into memory translated into screen codes.
4532 <sect1><tt>.MACPACK atari</tt><p>
4534 This macro package defines a macro named <tt/scrcode/. It takes a string
4535 as argument and places this string into memory translated into screen codes.
4538 <sect1><tt>.MACPACK cbm</tt><p>
4540 This macro package defines a macro named <tt/scrcode/. It takes a string
4541 as argument and places this string into memory translated into screen codes.
4544 <sect1><tt>.MACPACK cpu</tt><p>
4546 This macro package does not define any macros but constants used to examine
4547 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4548 each supported CPU a constant similar to
4560 is defined. These constants may be used to determine the exact type of the
4561 currently enabled CPU. In addition to that, for each CPU instruction set,
4562 another constant is defined:
4574 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4575 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4576 currently enabled CPU supports a specific instruction set. For example the
4577 65C02 supports all instructions of the 65SC02 CPU, so it has the
4578 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4582 .if (.cpu .bitand CPU_ISET_65SC02)
4590 it is possible to determine if the
4596 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4597 CPUs (the latter two are upwards compatible to the 65SC02).
4600 <sect1><tt>.MACPACK module</tt><p>
4602 This macro package defines a macro named <tt/module_header/. It takes an
4603 identifier as argument and is used to define the header of a module both
4604 in the dynamic and static variant.
4608 <sect>Predefined constants<label id="predefined-constants"><p>
4610 For better orthogonality, the assembler defines similar symbols as the
4611 compiler, depending on the target system selected:
4614 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4615 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4616 <item><tt/__ATARI2600__/ - Target system is <tt/atari2600/
4617 <item><tt/__ATARI5200__/ - Target system is <tt/atari5200/
4618 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4619 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4620 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4621 <item><tt/__BBC__/ - Target system is <tt/bbc/
4622 <item><tt/__C128__/ - Target system is <tt/c128/
4623 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4624 <item><tt/__C64__/ - Target system is <tt/c64/
4625 <item><tt/__CBM__/ - Target is a Commodore system
4626 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4627 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4628 <item><tt/__GEOS__/ - Target is a GEOS system
4629 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4630 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4631 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4632 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4633 <item><tt/__NES__/ - Target system is <tt/nes/
4634 <item><tt/__OSIC1P__/ - Target system is <tt/osic1p/
4635 <item><tt/__PET__/ - Target system is <tt/pet/
4636 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4637 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4638 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4639 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4640 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4644 <sect>Structs and unions<label id="structs"><p>
4646 <sect1>Structs and unions Overview<p>
4648 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4649 are to some degree comparable to their C counterparts. Both have a list of
4650 members. Each member allocates storage and may optionally have a name, which,
4651 in case of a struct, is the offset from the beginning and, in case of a union,
4655 <sect1>Declaration<p>
4657 Here is an example for a very simple struct with two members and a total size
4667 A union shares the total space between all its members, its size is the same
4668 as that of the largest member. The offset of all members relative to the union
4678 A struct or union must not necessarily have a name. If it is anonymous, no
4679 local scope is opened, the identifiers used to name the members are placed
4680 into the current scope instead.
4682 A struct may contain unnamed members and definitions of local structs. The
4683 storage allocators may contain a multiplier, as in the example below:
4688 .word 2 ; Allocate two words
4695 <sect1>The <tt/.TAG/ keyword<p>
4697 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4698 for an already defined struct or unions within another struct:
4712 Space for a struct or union may be allocated using the <ref id=".TAG"
4713 name=".TAG"> directive.
4719 Currently, members are just offsets from the start of the struct or union. To
4720 access a field of a struct, the member offset has to be added to the address
4721 of the struct itself:
4724 lda C+Circle::Radius ; Load circle radius into A
4727 This may change in a future version of the assembler.
4730 <sect1>Limitations<p>
4732 Structs and unions are currently implemented as nested symbol tables (in fact,
4733 they were a by-product of the improved scoping rules). Currently, the
4734 assembler has no idea of types. This means that the <ref id=".TAG"
4735 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4736 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4737 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4738 this structure accessible by using the '::' operator.
4742 <sect>Module constructors/destructors<label id="condes"><p>
4744 <em>Note:</em> This section applies mostly to C programs, so the explanation
4745 below uses examples from the C libraries. However, the feature may also be
4746 useful for assembler programs.
4749 <sect1>Module constructors/destructors Overview<p>
4751 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4752 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4753 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4754 special way. The linker is able to generate tables with all functions of a
4755 specific type. Such a table will <em>only</em> include symbols from object
4756 files that are linked into a specific executable. This may be used to add
4757 initialization and cleanup code for library modules, or a table of interrupt
4760 The C heap functions are an example where module initialization code is used.
4761 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4762 variables that contain the start and the end of the heap, pointers to the free
4763 list and so on. Since the end of the heap depends on the size and start of the
4764 stack, it must be initialized at runtime. However, initializing these
4765 variables for programs that do not use the heap are a waste of time and
4768 So the central module defines a function that contains initialization code and
4769 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4770 this module is added to an executable by the linker, the initialization
4771 function will be placed into the table of constructors by the linker. The C
4772 startup code will call all constructors before <tt/main/ and all destructors
4773 after <tt/main/, so without any further work, the heap initialization code is
4774 called once the module is linked in.
4776 While it would be possible to add explicit calls to initialization functions
4777 in the startup code, the new approach has several advantages:
4781 If a module is not included, the initialization code is not linked in and not
4782 called. So you don't pay for things you don't need.
4785 Adding another library that needs initialization does not mean that the
4786 startup code has to be changed. Before we had module constructors and
4787 destructors, the startup code for all systems had to be adjusted to call the
4788 new initialization code.
4791 The feature saves memory: Each additional initialization function needs just
4792 two bytes in the table (a pointer to the function).
4797 <sect1>Calling order<p>
4799 The symbols are sorted in increasing priority order by the linker when using
4800 one of the builtin linker configurations, so the functions with lower
4801 priorities come first and are followed by those with higher priorities. The C
4802 library runtime subroutine that walks over the function tables calls the
4803 functions starting from the top of the table - which means that functions with
4804 a high priority are called first.
4806 So when using the C runtime, functions are called with high priority functions
4807 first, followed by low priority functions.
4812 When using these special symbols, please take care of the following:
4817 The linker will only generate function tables, it will not generate code to
4818 call these functions. If you're using the feature in some other than the
4819 existing C environments, you have to write code to call all functions in a
4820 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4821 in the C runtime for an example on how to do this.
4824 The linker will only add addresses of functions that are in modules linked to
4825 the executable. This means that you have to be careful where to place the
4826 condes functions. If initialization or an irq handler is needed for a group of
4827 functions, be sure to place the function into a module that is linked in
4828 regardless of which function is called by the user.
4831 The linker will generate the tables only when requested to do so by the
4832 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4833 be requested separately.
4836 Constructors and destructors may have priorities. These priorities determine
4837 the order of the functions in the table. If your initialization or cleanup code
4838 does depend on other initialization or cleanup code, you have to choose the
4839 priority for the functions accordingly.
4842 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4843 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4844 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4845 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4846 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4847 (interruptor). The linker generates a separate table for each type on request.
4852 <sect>Porting sources from other assemblers<p>
4854 Sometimes it is necessary to port code written for older assemblers to ca65.
4855 In some cases, this can be done without any changes to the source code by
4856 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4857 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4860 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4861 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4862 done by the linker. Most other assemblers generate absolute code, placement is
4863 done within the assembler and there is no external linker.
4865 In general it is not a good idea to write new code using the emulation
4866 features of the assembler, but there may be situations where even this rule is
4871 You need to use some of the ca65 emulation features to simulate the behaviour
4872 of such simple assemblers.
4875 <item>Prepare your sourcecode like this:
4878 ; if you want TASS style labels without colons
4879 .feature labels_without_colons
4881 ; if you want TASS style character constants
4882 ; ("a" instead of the default 'a')
4883 .feature loose_char_term
4885 .word *+2 ; the cbm load address
4890 notice that the two emulation features are mostly useful for porting
4891 sources originally written in/for TASS, they are not needed for the
4892 actual "simple assembler operation" and are not recommended if you are
4893 writing new code from scratch.
4895 <item>Replace all program counter assignments (which are not possible in ca65
4896 by default, and the respective emulation feature works different from what
4897 you'd expect) by another way to skip to memory locations, for example the
4898 <tt><ref id=".RES" name=".RES"></tt> directive.
4902 .res $2000-* ; reserve memory up to $2000
4905 Please note that other than the original TASS, ca65 can never move the program
4906 counter backwards - think of it as if you are assembling to disk with TASS.
4908 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4909 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4910 of <tt/.goto/, everything involving loops must be replaced by
4911 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4913 <item>To assemble code to a different address than it is executed at, use the
4914 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4915 <tt/.offs/-constructs.
4922 .reloc ; back to normal
4925 <item>Then assemble like this:
4928 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4931 Note that you need to use the actual start address minus two, since two bytes
4932 are used for the cbm load address.
4939 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4940 Bassewitz. For usage of the binaries and/or sources the following
4941 conditions do apply:
4943 This software is provided 'as-is', without any expressed or implied
4944 warranty. In no event will the authors be held liable for any damages
4945 arising from the use of this software.
4947 Permission is granted to anyone to use this software for any purpose,
4948 including commercial applications, and to alter it and redistribute it
4949 freely, subject to the following restrictions:
4952 <item> The origin of this software must not be misrepresented; you must not
4953 claim that you wrote the original software. If you use this software
4954 in a product, an acknowledgment in the product documentation would be
4955 appreciated but is not required.
4956 <item> Altered source versions must be plainly marked as such, and must not
4957 be misrepresented as being the original software.
4958 <item> This notice may not be removed or altered from any source