1 <!doctype linuxdoc system> <!-- -*- text-mode -*- -->
4 <title>ca65 Users Guide
5 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
6 <date>2000-07-19, 2000-11-29, 2001-10-02, 2005-09-08
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 --forget-inc-paths Forget include search paths
116 --help Help (this text)
117 --ignore-case Ignore case of symbols
118 --include-dir dir Set an include directory search path
119 --large-alignment Don't warn about large alignments
120 --listing name Create a listing file if assembly was ok
121 --list-bytes n Maximum number of bytes per listing line
122 --macpack-dir dir Set a macro package directory
123 --memory-model model Set the memory model
124 --pagelength n Set the page length for the listing
125 --relax-checks Relax some checks (see docs)
126 --smart Enable smart mode
127 --target sys Set the target system
128 --verbose Increase verbosity
129 --version Print the assembler version
130 ---------------------------------------------------------------------------
134 <sect1>Command line options in detail<p>
136 Here is a description of all the command line options:
140 <label id="option--bin-include-dir">
141 <tag><tt>--bin-include-dir dir</tt></tag>
143 Name a directory which is searched for binary include files. The option
144 may be used more than once to specify more than one directory to search. The
145 current directory is always searched first before considering any
146 additional directories. See also the section about <ref id="search-paths"
147 name="search paths">.
150 <label id="option--cpu">
151 <tag><tt>--cpu type</tt></tag>
153 Set the default for the CPU type. The option takes a parameter, which
156 6502, 65SC02, 65C02, 65816, sunplus, sweet16, HuC6280
158 The sunplus cpu is not available in the freeware version, because the
159 instruction set is "proprietary and confidential".
162 <label id="option-create-dep">
163 <tag><tt>--create-dep name</tt></tag>
165 Tells the assembler to generate a file containing the dependency list for
166 the assembled module in makefile syntax. The output is written to a file
167 with the given name. The output does not include files passed via debug
168 information to the assembler.
171 <label id="option-create-full-dep">
172 <tag><tt>--create-full-dep name</tt></tag>
174 Tells the assembler to generate a file containing the dependency list for
175 the assembled module in makefile syntax. The output is written to a file
176 with the given name. The output does include files passed via debug
177 information to the assembler.
180 <tag><tt>-d, --debug</tt></tag>
182 Enables debug mode, something that should not be needed for mere
186 <label id="option--feature">
187 <tag><tt>--feature name</tt></tag>
189 Enable an emulation feature. This is identical as using <tt/.FEATURE/
190 in the source with two exceptions: Feature names must be lower case, and
191 each feature must be specified by using an extra <tt/--feature/ option,
192 comma separated lists are not allowed.
194 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
195 command for a list of emulation features.
198 <label id="option--forget-inc-paths">
199 <tag><tt>--forget-inc-paths</tt></tag>
201 Forget the builtin include paths. This is most useful when building
202 customized assembler modules, in which case the standard header files should
206 <label id="option-g">
207 <tag><tt>-g, --debug-info</tt></tag>
209 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
210 used, the assembler will add a section to the object file that contains
211 all symbols (including local ones) together with the symbol values and
212 source file positions. The linker will put these additional symbols into
213 the VICE label file, so even local symbols can be seen in the VICE
217 <label id="option-h">
218 <tag><tt>-h, --help</tt></tag>
220 Print the short option summary shown above.
223 <label id="option-i">
224 <tag><tt>-i, --ignore-case</tt></tag>
226 This option makes the assembler case insensitive on identifiers and labels.
227 This option will override the default, but may itself be overridden by the
228 <tt><ref id=".CASE" name=".CASE"></tt> control command.
231 <label id="option-l">
232 <tag><tt>-l name, --listing name</tt></tag>
234 Generate an assembler listing with the given name. A listing file will
235 never be generated in case of assembly errors.
238 <label id="option--large-alignment">
239 <tag><tt>--large-alignment</tt></tag>
241 Disable warnings about a large combined alignment. See the discussion of the
242 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
245 <label id="option--list-bytes">
246 <tag><tt>--list-bytes n</tt></tag>
248 Set the maximum number of bytes printed in the listing for one line of
249 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
250 for more information. The value zero can be used to encode an unlimited
251 number of printed bytes.
254 <label id="option--macpack-dir">
255 <tag><tt>--macpack-dir dir</tt></tag>
257 This options allows to specify a directory containing macro files that are
258 used instead of the builtin images when a <tt><ref id=".MACPACK"
259 name=".MACPACK"></tt> directive is encountered. If <tt>--macpack-dir</tt>
260 was specified, a <tt>.mac</tt> extension is added to the package name and
261 the resulting file is loaded from the given directory. This is most useful
262 when debugging the builtin macro packages.
265 <label id="option-mm">
266 <tag><tt>-mm model, --memory-model model</tt></tag>
268 Define the default memory model. Possible model specifiers are near, far and
272 <label id="option-o">
273 <tag><tt>-o name</tt></tag>
275 The default output name is the name of the input file with the extension
276 replaced by ".o". If you don't like that, you may give another name with
277 the -o option. The output file will be placed in the same directory as
278 the source file, or, if -o is given, the full path in this name is used.
281 <label id="option--pagelength">
282 <tag><tt>--pagelength n</tt></tag>
284 sets the length of a listing page in lines. See the <tt><ref
285 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
288 <label id="option--relax-checks">
289 <tag><tt>--relax-checks</tt></tag>
291 Relax some checks done by the assembler. This will allow code that is an
292 error in most cases and flagged as such by the assembler, but can be valid
293 in special situations.
297 <item>Short branches between two different segments.
298 <item>Byte sized address loads where the address is not a zeropage address.
302 <label id="option-s">
303 <tag><tt>-s, --smart-mode</tt></tag>
305 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
306 pseudo instruction) the assembler will track usage of the <tt/REP/ and
307 <tt/SEP/ instructions in 65816 mode and update the operand sizes
308 accordingly. If the operand of such an instruction cannot be evaluated by
309 the assembler (for example, because the operand is an imported symbol), a
312 Beware: Since the assembler cannot trace the execution flow this may
313 lead to false results in some cases. If in doubt, use the .ixx and .axx
314 instructions to tell the assembler about the current settings. Smart
315 mode is off by default.
318 <label id="option-t">
319 <tag><tt>-t sys, --target sys</tt></tag>
321 Set the target system. This will enable translation of character strings and
322 character constants into the character set of the target platform. The
323 default for the target system is "none", which means that no translation
324 will take place. The assembler supports the same target systems as the
325 compiler, see there for a list.
327 Depending on the target, the default CPU type is also set. This can be
328 overriden by using the <tt/<ref id="option--cpu" name="--cpu">/ option.
331 <label id="option-v">
332 <tag><tt>-v, --verbose</tt></tag>
334 Increase the assembler verbosity. Usually only needed for debugging
335 purposes. You may use this option more than one time for even more
339 <label id="option-D">
340 <tag><tt>-D</tt></tag>
342 This option allows you to define symbols on the command line. Without a
343 value, the symbol is defined with the value zero. When giving a value,
344 you may use the '$' prefix for hexadecimal symbols. Please note
345 that for some operating systems, '$' has a special meaning, so
346 you may have to quote the expression.
349 <label id="option-I">
350 <tag><tt>-I dir, --include-dir dir</tt></tag>
352 Name a directory which is searched for include files. The option may be
353 used more than once to specify more than one directory to search. The
354 current directory is always searched first before considering any
355 additional directories. See also the section about <ref id="search-paths"
356 name="search paths">.
359 <label id="option-U">
360 <tag><tt>-U, --auto-import</tt></tag>
362 Mark symbols that are not defined in the sources as imported symbols. This
363 should be used with care since it delays error messages about typos and such
364 until the linker is run. The compiler uses the equivalent of this switch
365 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
366 symbols for the runtime library. However, the compiler is supposed to
367 generate code that runs through the assembler without problems, something
368 which is not always true for assembler programmers.
371 <label id="option-V">
372 <tag><tt>-V, --version</tt></tag>
374 Print the version number of the assembler. If you send any suggestions
375 or bugfixes, please include the version number.
378 <label id="option-W">
379 <tag><tt>-Wn</tt></tag>
381 Set the warning level for the assembler. Using -W2 the assembler will
382 even warn about such things like unused imported symbols. The default
383 warning level is 1, and it would probably be silly to set it to
391 <sect>Search paths<label id="search-paths"><p>
393 Normal include files are searched in the following places:
396 <item>The current directory.
397 <item>A compiled-in directory, which is often <tt>/usr/lib/cc65/asminc</tt>
399 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
400 <item>A subdirectory named <tt/asminc/ of the directory defined in the
401 environment variable <tt/CC65_HOME/, if it is defined.
402 <item>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
406 Binary include files are searched in the following places:
409 <item>The current directory.
410 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
411 name="--bin-include-dir">/ option on the command line.
416 <sect>Input format<p>
418 <sect1>Assembler syntax<p>
420 The assembler accepts the standard 6502/65816 assembler syntax. One line may
421 contain a label (which is identified by a colon), and, in addition to the
422 label, an assembler mnemonic, a macro, or a control command (see section <ref
423 id="control-commands" name="Control Commands"> for supported control
424 commands). Alternatively, the line may contain a symbol definition using
425 the '=' token. Everything after a semicolon is handled as a comment (that is,
428 Here are some examples for valid input lines:
431 Label: ; A label and a comment
432 lda #$20 ; A 6502 instruction plus comment
433 L1: ldx #$20 ; Same with label
434 L2: .byte "Hello world" ; Label plus control command
435 mymac $20 ; Macro expansion
436 MySym = 3*L1 ; Symbol definition
437 MaSym = Label ; Another symbol
440 The assembler accepts
443 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
444 <tt><ref id=".P02" name=".P02"></tt> command was given).
445 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
446 <ref id="6502X-mode" name="6502X mode">.
447 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
448 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
449 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
450 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
451 <item>all valid 65618 mnemonics when in 65816 mode (after the
452 <tt><ref id=".P816" name=".P816"></tt> command was given).
453 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
454 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
460 In 65816 mode several aliases are accepted in addition to the official
464 BGE is an alias for BCS
465 BLT is an alias for BCC
466 CPA is an alias for CMP
467 DEA is an alias for DEC A
468 INA is an alias for INC A
469 SWA is an alias for XBA
470 TAD is an alias for TCD
471 TAS is an alias for TCS
472 TDA is an alias for TDC
473 TSA is an alias for TSC
478 <sect1>6502X mode<label id="6502X-mode"><p>
480 6502X mode is an extension to the normal 6502 mode. In this mode, several
481 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
482 these instructions are illegal, there are no official mnemonics for them. The
483 unofficial ones are taken from <htmlurl
484 url="http://www.oxyron.de/html/opcodes02.html"
485 name="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
486 ones marked as "stable" are supported. The following table uses information
487 from the mentioned web page, for more information, see there.
490 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
491 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
492 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
493 <item><tt>AXS: X:=A and X-#{imm};</tt>
494 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
495 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
496 <item><tt>LAS: A,X,S:={adr} and S;</tt>
497 <item><tt>LAX: A,X:={adr};</tt>
498 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
499 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
500 <item><tt>SAX: {adr}:=A and X;</tt>
501 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
502 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
507 <sect1>sweet16 mode<label id="sweet16-mode"><p>
509 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
510 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
511 generate code for this pseudo CPU when switched into sweet16 mode. The
512 following is special in sweet16 mode:
516 <item>The '@' character denotes indirect addressing and is no longer available
517 for cheap local labels. If you need cheap local labels, you will have to
518 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
519 name=".LOCALCHAR">/ command.
521 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
522 these identifiers are reserved words.
526 Please note that the assembler does neither supply the interpreter needed for
527 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
528 nor does it call the interpreter. All this must be done by your program. Apple
529 ][ programmers do probably know how to use sweet16 mode.
531 For more information about SWEET 16, see
532 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
533 name="http://www.6502.org/source/interpreters/sweet16.htm">.
536 <sect1>Number format<p>
538 For literal values, the assembler accepts the widely used number formats: A
539 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
540 denotes a binary value, and a bare number is interpreted as a decimal. There
541 are currently no octal values and no floats.
544 <sect1>Conditional assembly<p>
546 Please note that when using the conditional directives (<tt/.IF/ and friends),
547 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
548 that are not assembled. The reason for this behaviour is that the assembler
549 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
550 conversion of the input stream into tokens still takes place. As a consequence
551 conditional assembly directives may <bf/not/ be used to prevent normal text
552 (used as a comment or similar) from being assembled. <p>
558 <sect1>Expression evaluation<p>
560 All expressions are evaluated with (at least) 32 bit precision. An
561 expression may contain constant values and any combination of internal and
562 external symbols. Expressions that cannot be evaluated at assembly time
563 are stored inside the object file for evaluation by the linker.
564 Expressions referencing imported symbols must always be evaluated by the
568 <sect1>Size of an expression result<p>
570 Sometimes, the assembler must know about the size of the value that is the
571 result of an expression. This is usually the case, if a decision has to be
572 made, to generate a zero page or an absolute memory references. In this
573 case, the assembler has to make some assumptions about the result of an
577 <item> If the result of an expression is constant, the actual value is
578 checked to see if it's a byte sized expression or not.
579 <item> If the expression is explicitly casted to a byte sized expression by
580 one of the '>', '<' or '^' operators, it is a byte expression.
581 <item> If this is not the case, and the expression contains a symbol,
582 explicitly declared as zero page symbol (by one of the .importzp or
583 .exportzp instructions), then the whole expression is assumed to be
585 <item> If the expression contains symbols that are not defined, and these
586 symbols are local symbols, the enclosing scopes are searched for a
587 symbol with the same name. If one exists and this symbol is defined,
588 its attributes are used to determine the result size.
589 <item> In all other cases the expression is assumed to be word sized.
592 Note: If the assembler is not able to evaluate the expression at assembly
593 time, the linker will evaluate it and check for range errors as soon as
597 <sect1>Boolean expressions<p>
599 In the context of a boolean expression, any non zero value is evaluated as
600 true, any other value to false. The result of a boolean expression is 1 if
601 it's true, and zero if it's false. There are boolean operators with extreme
602 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
603 operators are shortcut operators. That is, if the result of the expression is
604 already known, after evaluating the left hand side, the right hand side is
608 <sect1>Constant expressions<p>
610 Sometimes an expression must evaluate to a constant without looking at any
611 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
612 that decides if parts of the code are assembled or not. An expression used in
613 the <tt/.IF/ command cannot reference a symbol defined later, because the
614 decision about the <tt/.IF/ must be made at the point when it is read. If the
615 expression used in such a context contains only constant numerical values,
616 there is no problem. When unresolvable symbols are involved it may get harder
617 for the assembler to determine if the expression is actually constant, and it
618 is even possible to create expressions that aren't recognized as constant.
619 Simplifying the expressions will often help.
621 In cases where the result of the expression is not needed immediately, the
622 assembler will delay evaluation until all input is read, at which point all
623 symbols are known. So using arbitrary complex constant expressions is no
624 problem in most cases.
628 <sect1>Available operators<label id="operators"><p>
632 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
633 | Built-in string functions| 0@
635 | Built-in pseudo-variables| 1@
636 | Built-in pseudo-functions| 1@
637 +| Unary positive| 1@
638 -| Unary negative| 1@
640 .BITNOT| Unary bitwise not| 1@
642 .LOBYTE| Unary low-byte operator| 1@
644 .HIBYTE| Unary high-byte operator| 1@
646 .BANKBYTE| Unary bank-byte operator| 1@
648 *| Multiplication| 2@
650 .MOD| Modulo operator| 2@
652 .BITAND| Bitwise and| 2@
654 .BITXOR| Binary bitwise xor| 2@
656 .SHL| Shift-left operator| 2@
658 .SHR| Shift-right operator| 2@
660 +| Binary addition| 3@
661 -| Binary subtraction| 3@
663 .BITOR| Bitwise or| 3@
665 = | Compare operator (equal)| 4@
666 <>| Compare operator (not equal)| 4@
667 <| Compare operator (less)| 4@
668 >| Compare operator (greater)| 4@
669 <=| Compare operator (less or equal)| 4@
670 >=| Compare operator (greater or equal)| 4@
673 .AND| Boolean and| 5@
674 .XOR| Boolean xor| 5@
676 ||<newline>
680 .NOT| Boolean not| 7@<hline>
682 <caption>Available operators, sorted by precedence
685 To force a specific order of evaluation, parentheses may be used, as usual.
689 <sect>Symbols and labels<p>
691 A symbol or label is an identifier that starts with a letter and is followed
692 by letters and digits. Depending on some features enabled (see
693 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
694 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
695 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
696 other characters may be present. Use of identifiers consisting of a single
697 character will not work in all cases, because some of these identifiers are
698 reserved keywords (for example "A" is not a valid identifier for a label,
699 because it is the keyword for the accumulator).
701 The assembler allows you to use symbols instead of naked values to make
702 the source more readable. There are a lot of different ways to define and
703 use symbols and labels, giving a lot of flexibility.
705 <sect1>Numeric constants<p>
707 Numeric constants are defined using the equal sign or the label assignment
708 operator. After doing
714 may use the symbol "two" in every place where a number is expected, and it is
715 evaluated to the value 2 in this context. The label assignment operator is
716 almost identical, but causes the symbol to be marked as a label, so it may be
717 handled differently in a debugger:
723 The right side can of course be an expression:
730 <label id="variables">
731 <sect1>Numeric variables<p>
733 Within macros and other control structures (<tt><ref id=".REPEAT"
734 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
735 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
736 symbol that may get assigned a different value later:
740 lda #four ; Loads 4 into A
742 lda #four ; Loads 3 into A
745 Since the value of the symbol can change later, it must be possible to
746 evaluate it when used (no delayed evaluation as with normal symbols). So the
747 expression used as the value must be constant.
749 Following is an example for a macro that generates a different label each time
750 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
751 and a numeric variable named <tt>lcount</tt>.
754 .lcount .set 0 ; Initialize the counter
757 .ident (.sprintf ("L%04X", lcount)):
758 lcount .set lcount + 1
763 <sect1>Standard labels<p>
765 A label is defined by writing the name of the label at the start of the line
766 (before any instruction mnemonic, macro or pseudo directive), followed by a
767 colon. This will declare a symbol with the given name and the value of the
768 current program counter.
771 <sect1>Local labels and symbols<p>
773 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
774 create regions of code where the names of labels and symbols are local to this
775 region. They are not known outside of this region and cannot be accessed from
776 there. Such regions may be nested like PROCEDUREs in Pascal.
778 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
779 directive for more information.
782 <sect1>Cheap local labels<p>
784 Cheap local labels are defined like standard labels, but the name of the
785 label must begin with a special symbol (usually '@', but this can be
786 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
789 Cheap local labels are visible only between two non cheap labels. As soon as a
790 standard symbol is encountered (this may also be a local symbol if inside a
791 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
792 cheap local symbol goes out of scope.
794 You may use cheap local labels as an easy way to reuse common label
795 names like "Loop". Here is an example:
798 Clear: lda #$00 ; Global label
800 @Loop: sta Mem,y ; Local label
804 Sub: ... ; New global label
805 bne @Loop ; ERROR: Unknown identifier!
808 <sect1>Unnamed labels<p>
810 If you really want to write messy code, there are also unnamed labels. These
811 labels do not have a name (you guessed that already, didn't you?). A colon is
812 used to mark the absence of the name.
814 Unnamed labels may be accessed by using the colon plus several minus or plus
815 characters as a label designator. Using the '-' characters will create a back
816 reference (use the n'th label backwards), using '+' will create a forward
817 reference (use the n'th label in forward direction). An example will help to
840 As you can see from the example, unnamed labels will make even short
841 sections of code hard to understand, because you have to count labels
842 to find branch targets (this is the reason why I for my part do
843 prefer the "cheap" local labels). Nevertheless, unnamed labels are
844 convenient in some situations, so it's your decision.
846 <bf/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
847 unnamed ones, so scopes don't have an effect on unnamed labels.
851 <sect1>Using macros to define labels and constants<p>
853 While there are drawbacks with this approach, it may be handy in a few rare
854 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
855 to define symbols or constants that may be used elsewhere. One of the
856 advantages is that you can use it to define string constants (this is not
857 possible with the other symbol types).
859 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
860 so the names do not adhere to scoping, diagnostics may be misleading, there
861 are no symbols to look up in the map file, and there is no debug info.
862 Especially the first problem in the list can lead to very nasty programming
863 errors. Because of these problems, the general advice is, <bf/NOT/ do use
864 <tt/.DEFINE/ if you don't have to.
870 .DEFINE version "SOS V2.3"
872 four = two * two ; Ok
875 .PROC ; Start local scope
876 two = 3 ; Will give "2 = 3" - invalid!
881 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
883 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
884 id="option-g" name="-g"> is given on the command line), global, local and
885 cheap local labels are written to the object file and will be available in the
886 symbol file via the linker. Unnamed labels are not written to the object file,
887 because they don't have a name which would allow to access them.
891 <sect>Scopes<label id="scopes"><p>
893 ca65 implements several sorts of scopes for symbols.
895 <sect1>Global scope<p>
897 All (non cheap local) symbols that are declared outside of any nested scopes
901 <sect1>Cheap locals<p>
903 A special scope is the scope for cheap local symbols. It lasts from one non
904 local symbol to the next one, without any provisions made by the programmer.
905 All other scopes differ in usage but use the same concept internally.
908 <sect1>Generic nested scopes<p>
910 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
911 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
912 The scope can have a name, in which case it is accessible from the outside by
913 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
914 have a name, all symbols created within the scope are local to the scope, and
915 aren't accessible from the outside.
917 A nested scope can access symbols from the local or from enclosing scopes by
918 name without using explicit scope names. In some cases there may be
919 ambiguities, for example if there is a reference to a local symbol that is not
920 yet defined, but a symbol with the same name exists in outer scopes:
932 In the example above, the <tt/lda/ instruction will load the value 3 into the
933 accumulator, because <tt/foo/ is redefined in the scope. However:
945 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
946 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
947 absolute mode is used instead. In fact, the assembler will not use absolute
948 mode by default, but it will search through the enclosing scopes for a symbol
949 with the given name. If one is found, the address size of this symbol is used.
950 This may lead to errors:
962 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
963 instruction, it will search for an already defined symbol <tt/foo/. It will
964 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
965 zeropage symbol. So the assembler will use zeropage addressing mode. If
966 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
967 the address in the <tt/lda/ instruction already translated, but since the new
968 value needs absolute addressing mode, this fails, and an error message "Range
971 Of course the most simple solution for the problem is to move the definition
972 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
973 rare cases when this cannot be done. In these cases, you can use one of the
974 address size override operators:
986 This will cause the <tt/lda/ instruction to be translated using absolute
987 addressing mode, which means changing the symbol reference later does not
991 <sect1>Nested procedures<p>
993 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
994 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
995 name, and a it will introduce a symbol with this name in the enclosing scope.
1004 is actually the same as
1013 This is the reason why a procedure must have a name. If you want a scope
1014 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
1016 <bf/Note:/ As you can see from the example above, scopes and symbols live in
1017 different namespaces. There can be a symbol named <tt/foo/ and a scope named
1018 <tt/foo/ without any conflicts (but see the section titled <ref
1019 id="scopesearch" name=""Scope search order"">).
1022 <sect1>Structs, unions and enums<p>
1024 Structs, unions and enums are explained in a <ref id="structs" name="separate
1025 section">, I do only cover them here, because if they are declared with a
1026 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
1027 name=".SCOPE">/. However, when no name is specified, the behaviour is
1028 different: In this case, no new scope will be opened, symbols declared within
1029 a struct, union, or enum declaration will then be added to the enclosing scope
1033 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1035 Accessing symbols from other scopes is possible by using an explicit scope
1036 specification, provided that the scope where the symbol lives in has a name.
1037 The namespace token (<tt/::/) is used to access other scopes:
1045 lda foo::bar ; Access foo in scope bar
1048 The only way to deny access to a scope from the outside is to declare a scope
1049 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1051 A special syntax is used to specify the global scope: If a symbol or scope is
1052 preceded by the namespace token, the global scope is searched:
1059 lda #::bar ; Access the global bar (which is 3)
1064 <sect1>Scope search order<label id="scopesearch"><p>
1066 The assembler searches for a scope in a similar way as for a symbol. First, it
1067 looks in the current scope, and then it walks up the enclosing scopes until
1070 However, one important thing to note when using explicit scope syntax is, that
1071 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1072 used without a preceding definition. This means that in the following
1081 lda #foo::bar ; Will load 3, not 2!
1088 the reference to the scope <tt/foo/ will use the global scope, and not the
1089 local one, because the local one is not visible at the point where it is
1092 Things get more complex if a complete chain of scopes is specified:
1103 lda #outer::inner::bar ; 1
1115 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1116 assembler will first search in the local scope for a scope named <tt/outer/.
1117 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1118 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1119 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1120 this scope, the assembler looks for a symbol named <tt/bar/.
1122 Please note that once the anchor scope is found, all following scopes
1123 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1124 assembler will search the scope tree only for the first scope (if it is not
1125 anchored in the root scope). Starting from there on, there is no flexibility,
1126 so if the scope named <tt/outer/ found by the assembler does not contain a
1127 scope named <tt/inner/, this would be an error, even if such a pair does exist
1128 (one level up in global scope).
1130 Ambiguities that may be introduced by this search algorithm may be removed by
1131 anchoring the scope specification in the global scope. In the example above,
1132 if you want to access the "other" symbol <tt/bar/, you would have to write:
1143 lda #::outer::inner::bar ; 2
1156 <sect>Address sizes and memory models<label id="address-sizes"><p>
1158 <sect1>Address sizes<p>
1160 ca65 assigns each segment and each symbol an address size. This is true, even
1161 if the symbol is not used as an address. You may also think of a value range
1162 of the symbol instead of an address size.
1164 Possible address sizes are:
1167 <item>Zeropage or direct (8 bits)
1168 <item>Absolute (16 bits)
1170 <item>Long (32 bits)
1173 Since the assembler uses default address sizes for the segments and symbols,
1174 it is usually not necessary to override the default behaviour. In cases, where
1175 it is necessary, the following keywords may be used to specify address sizes:
1178 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1179 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1180 <item>FAR for far addressing (24 bits).
1181 <item>LONG or DWORD for long addressing (32 bits).
1185 <sect1>Address sizes of segments<p>
1187 The assembler assigns an address size to each segment. Since the
1188 representation of a label within this segment is "segment start + offset",
1189 labels will inherit the address size of the segment they are declared in.
1191 The address size of a segment may be changed, by using an optional address
1192 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1193 an explanation on how this is done.
1196 <sect1>Address sizes of symbols<p>
1201 <sect1>Memory models<p>
1203 The default address size of a segment depends on the memory model used. Since
1204 labels inherit the address size from the segment they are declared in,
1205 changing the memory model is an easy way to change the address size of many
1211 <sect>Pseudo variables<label id="pseudo-variables"><p>
1213 Pseudo variables are readable in all cases, and in some special cases also
1216 <sect1><tt>*</tt><p>
1218 Reading this pseudo variable will return the program counter at the start
1219 of the current input line.
1221 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1222 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1223 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1226 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1228 Reading this pseudo variable will give a constant integer value that
1229 tells which CPU is currently enabled. It can also tell which instruction
1230 set the CPU is able to translate. The value read from the pseudo variable
1231 should be further examined by using one of the constants defined by the
1232 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1234 It may be used to replace the .IFPxx pseudo instructions or to construct
1235 even more complex expressions.
1241 .if (.cpu .bitand CPU_ISET_65816)
1253 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1255 This builtin pseudo variable is only available in macros. It is replaced by
1256 the actual number of parameters that were given in the macro invocation.
1261 .macro foo arg1, arg2, arg3
1262 .if .paramcount <> 3
1263 .error "Too few parameters for macro foo"
1269 See section <ref id="macros" name="Macros">.
1272 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1274 Reading this pseudo variable will give a constant integer value that
1275 represents the current time in POSIX standard (as seconds since the
1278 It may be used to encode the time of translation somewhere in the created
1284 .dword .time ; Place time here
1288 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1290 Reading this pseudo variable will give the assembler version according to
1291 the following formula:
1293 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1295 It may be used to encode the assembler version or check the assembler for
1296 special features not available with older versions.
1300 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1301 reading the pseudo variable <tt/.VERSION/.
1305 <sect>Pseudo functions<label id="pseudo-functions"><p>
1307 Pseudo functions expect their arguments in parenthesis, and they have a result,
1308 either a string or an expression.
1311 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1313 The <tt/.BANK/ function is used to support systems with banked memory. The
1314 argument is an expression with exactly one segment reference - usually a
1315 label. The function result is the value of the <tt/bank/ attribute assigned
1316 to the run memory area of the segment. Please see the linker documentation
1317 for more information about memory areas and their attributes.
1319 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1320 containing specific data is available.
1322 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1323 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1324 name=".LOBYTE"></tt> or similar functions to address just part of it.
1326 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1327 an expression containing <tt/.BANK/ can never be used where a constant known
1328 result is expected (for example with <tt/.RES/).
1345 .byte <.BANK (banked_func_1)
1348 .byte <.BANK (banked_func_2)
1354 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1356 The function returns the bank byte (that is, bits 16-23) of its argument.
1357 It works identical to the '^' operator.
1359 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1360 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1363 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1365 Builtin function. The function evaluates its argument in braces and yields
1366 "false" if the argument is non blank (there is an argument), and "true" if
1367 there is no argument. The token list that makes up the function argument
1368 may optionally be enclosed in curly braces. This allows the inclusion of
1369 tokens that would otherwise terminate the list (the closing right
1370 parenthesis). The curly braces are not considered part of the list, a list
1371 just consisting of curly braces is considered to be empty.
1373 As an example, the <tt/.IFBLANK/ statement may be replaced by
1381 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1383 Builtin string function. The function allows to concatenate a list of string
1384 constants separated by commas. The result is a string constant that is the
1385 concatenation of all arguments. This function is most useful in macros and
1386 when used together with the <tt/.STRING/ builtin function. The function may
1387 be used in any case where a string constant is expected.
1392 .include .concat ("myheader", ".", "inc")
1395 This is the same as the command
1398 .include "myheader.inc"
1402 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1404 Builtin function. The function evaluates its argument in braces and
1405 yields "true" if the argument is a constant expression (that is, an
1406 expression that yields a constant value at assembly time) and "false"
1407 otherwise. As an example, the .IFCONST statement may be replaced by
1414 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1416 The function returns the high byte (that is, bits 8-15) of its argument.
1417 It works identical to the '>' operator.
1419 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1420 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1423 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1425 The function returns the high word (that is, bits 16-31) of its argument.
1427 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1430 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1432 The function expects a string as its argument, and converts this argument
1433 into an identifier. If the string starts with the current <tt/<ref
1434 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1435 identifier, otherwise it will be converted into a normal identifier.
1440 .macro makelabel arg1, arg2
1441 .ident (.concat (arg1, arg2)):
1444 makelabel "foo", "bar"
1446 .word foobar ; Valid label
1450 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1452 Builtin function. Extracts the left part of a given token list.
1457 .LEFT (<int expr>, <token list>)
1460 The first integer expression gives the number of tokens to extract from
1461 the token list. The second argument is the token list itself. The token
1462 list may optionally be enclosed into curly braces. This allows the
1463 inclusion of tokens that would otherwise terminate the list (the closing
1464 right paren in the given case).
1468 To check in a macro if the given argument has a '#' as first token
1469 (immediate addressing mode), use something like this:
1474 .if (.match (.left (1, {arg}), #))
1476 ; ldax called with immediate operand
1484 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1485 name=".RIGHT"></tt> builtin functions.
1488 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1490 The function returns the low byte (that is, bits 0-7) of its argument.
1491 It works identical to the '<' operator.
1493 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1494 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1497 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1499 The function returns the low word (that is, bits 0-15) of its argument.
1501 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1504 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1506 Builtin function. Matches two token lists against each other. This is
1507 most useful within macros, since macros are not stored as strings, but
1513 .MATCH(<token list #1>, <token list #2>)
1516 Both token list may contain arbitrary tokens with the exception of the
1517 terminator token (comma resp. right parenthesis) and
1524 The token lists may optionally be enclosed into curly braces. This allows
1525 the inclusion of tokens that would otherwise terminate the list (the closing
1526 right paren in the given case). Often a macro parameter is used for any of
1529 Please note that the function does only compare tokens, not token
1530 attributes. So any number is equal to any other number, regardless of the
1531 actual value. The same is true for strings. If you need to compare tokens
1532 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1533 name=".XMATCH"></tt> function.
1537 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1538 while honoring the sign bit. The builtin processor instructions will allow
1539 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1540 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1541 to check for this and print and error for invalid calls.
1546 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1547 .error "Syntax error"
1550 cmp #$80 ; Bit 7 into carry
1551 lsr a ; Shift carry into bit 7
1556 The macro will only accept no arguments, or one argument that must be the
1557 reserved keyword "A".
1559 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1562 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1564 Builtin function. The result is the larger of two values.
1569 .MAX (<value #1>, <value #2>)
1575 ; Reserve space for the larger of two data blocks
1576 savearea: .max (.sizeof (foo), .sizeof (bar))
1579 See: <tt><ref id=".MIN" name=".MIN"></tt>
1582 <sect1><tt>.MID</tt><label id=".MID"><p>
1584 Builtin function. Takes a starting index, a count and a token list as
1585 arguments. Will return part of the token list.
1590 .MID (<int expr>, <int expr>, <token list>)
1593 The first integer expression gives the starting token in the list (the first
1594 token has index 0). The second integer expression gives the number of tokens
1595 to extract from the token list. The third argument is the token list itself.
1596 The token list may optionally be enclosed into curly braces. This allows the
1597 inclusion of tokens that would otherwise terminate the list (the closing
1598 right paren in the given case).
1602 To check in a macro if the given argument has a '<tt/#/' as first token
1603 (immediate addressing mode), use something like this:
1608 .if (.match (.mid (0, 1, {arg}), #))
1610 ; ldax called with immediate operand
1618 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1619 name=".RIGHT"></tt> builtin functions.
1622 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1624 Builtin function. The result is the smaller of two values.
1629 .MIN (<value #1>, <value #2>)
1635 ; Reserve space for some data, but 256 bytes minimum
1636 savearea: .min (.sizeof (foo), 256)
1639 See: <tt><ref id=".MAX" name=".MAX"></tt>
1642 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1644 Builtin function. The function expects an identifier as argument in braces.
1645 The argument is evaluated, and the function yields "true" if the identifier
1646 is a symbol that has already been referenced somewhere in the source file up
1647 to the current position. Otherwise the function yields false. As an example,
1648 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1654 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1657 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1659 Builtin function. Extracts the right part of a given token list.
1664 .RIGHT (<int expr>, <token list>)
1667 The first integer expression gives the number of tokens to extract from the
1668 token list. The second argument is the token list itself. The token list
1669 may optionally be enclosed into curly braces. This allows the inclusion of
1670 tokens that would otherwise terminate the list (the closing right paren in
1673 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1674 name=".MID"></tt> builtin functions.
1677 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1679 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1680 argument can be a struct/union, a struct member, a procedure, or a label. In
1681 case of a procedure or label, its size is defined by the amount of data
1682 placed in the segment where the label is relative to. If a line of code
1683 switches segments (for example in a macro) data placed in other segments
1684 does not count for the size.
1686 Please note that a symbol or scope must exist, before it is used together with
1687 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1688 A scope has preference over a symbol with the same name, so if the last part
1689 of a name represents both, a scope and a symbol, the scope is chosen over the
1692 After the following code:
1695 .struct Point ; Struct size = 4
1700 P: .tag Point ; Declare a point
1701 @P: .tag Point ; Declare another point
1713 .data ; Segment switch!!!
1719 <tag><tt/.sizeof(Point)/</tag>
1720 will have the value 4, because this is the size of struct <tt/Point/.
1722 <tag><tt/.sizeof(Point::xcoord)/</tag>
1723 will have the value 2, because this is the size of the member <tt/xcoord/
1724 in struct <tt/Point/.
1726 <tag><tt/.sizeof(P)/</tag>
1727 will have the value 4, this is the size of the data declared on the same
1728 source line as the label <tt/P/, which is in the same segment that <tt/P/
1731 <tag><tt/.sizeof(@P)/</tag>
1732 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1733 does also work for cheap local symbols.
1735 <tag><tt/.sizeof(Code)/</tag>
1736 will have the value 3, since this is amount of data emitted into the code
1737 segment, the segment that was active when <tt/Code/ was entered. Note that
1738 this value includes the amount of data emitted in child scopes (in this
1739 case <tt/Code::Inner/).
1741 <tag><tt/.sizeof(Code::Inner)/</tag>
1742 will have the value 1 as expected.
1744 <tag><tt/.sizeof(Data)/</tag>
1745 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1746 the segment is switched after entry, this data is emitted into another
1751 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1753 Builtin function. The function accepts a string and an index as
1754 arguments and returns the value of the character at the given position
1755 as an integer value. The index is zero based.
1761 ; Check if the argument string starts with '#'
1762 .if (.strat (Arg, 0) = '#')
1769 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1771 Builtin function. It expects a format string as first argument. The number
1772 and type of the following arguments depend on the format string. The format
1773 string is similar to the one of the C <tt/printf/ function. Missing things
1774 are: Length modifiers, variable width.
1776 The result of the function is a string.
1783 ; Generate an identifier:
1784 .ident (.sprintf ("%s%03d", "label", num)):
1788 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1790 Builtin function. The function accepts an argument in braces and converts
1791 this argument into a string constant. The argument may be an identifier, or
1792 a constant numeric value.
1794 Since you can use a string in the first place, the use of the function may
1795 not be obvious. However, it is useful in macros, or more complex setups.
1800 ; Emulate other assemblers:
1802 .segment .string(name)
1807 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1809 Builtin function. The function accepts a string argument in braces and
1810 evaluates to the length of the string.
1814 The following macro encodes a string as a pascal style string with
1815 a leading length byte.
1819 .byte .strlen(Arg), Arg
1824 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1826 Builtin function. The function accepts a token list in braces. The function
1827 result is the number of tokens given as argument. The token list may
1828 optionally be enclosed into curly braces which are not considered part of
1829 the list and not counted. Enclosement in curly braces allows the inclusion
1830 of tokens that would otherwise terminate the list (the closing right paren
1835 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1836 with the normal 6502 instructions). To translate it into two separate 8 bit
1837 load instructions, the '#' token has to get stripped from the argument:
1841 .if (.match (.mid (0, 1, {arg}), #))
1842 ; ldax called with immediate operand
1843 lda #<(.right (.tcount ({arg})-1, {arg}))
1844 ldx #>(.right (.tcount ({arg})-1, {arg}))
1852 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1854 Builtin function. Matches two token lists against each other. This is
1855 most useful within macros, since macros are not stored as strings, but
1861 .XMATCH(<token list #1>, <token list #2>)
1864 Both token list may contain arbitrary tokens with the exception of the
1865 terminator token (comma resp. right parenthesis) and
1872 The token lists may optionally be enclosed into curly braces. This allows
1873 the inclusion of tokens that would otherwise terminate the list (the closing
1874 right paren in the given case). Often a macro parameter is used for any of
1877 The function compares tokens <em/and/ token values. If you need a function
1878 that just compares the type of tokens, have a look at the <tt><ref
1879 id=".MATCH" name=".MATCH"></tt> function.
1881 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1885 <sect>Control commands<label id="control-commands"><p>
1887 Here's a list of all control commands and a description, what they do:
1890 <sect1><tt>.A16</tt><label id=".A16"><p>
1892 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1894 Note: This command will not emit any code, it will tell the assembler to
1895 create 16 bit operands for immediate accumulator addressing mode.
1897 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1900 <sect1><tt>.A8</tt><label id=".A8"><p>
1902 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1904 Note: This command will not emit any code, it will tell the assembler to
1905 create 8 bit operands for immediate accu addressing mode.
1907 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1910 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1912 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1913 may be used for better readability if the data words are address values. In
1914 65816 mode, the address is forced to be 16 bit wide to fit into the current
1915 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1916 must be followed by a sequence of (not necessarily constant) expressions.
1921 .addr $0D00, $AF13, _Clear
1924 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1928 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1930 Align data to a given boundary. The command expects a constant integer
1931 argument in the range 1 ... 65536, plus an optional second argument
1932 in byte range. If there is a second argument, it is used as fill value,
1933 otherwise the value defined in the linker configuration file is used
1934 (the default for this value is zero).
1936 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1937 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1938 number of bytes, since that would break address calculations within the
1939 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1940 of the alignment, because that allows the number of fill bytes to be
1941 calculated in advance by the assembler. You are therefore required to
1942 specify a matching alignment for the segment in the linker config. The
1943 linker will output a warning if the alignment of the segment is less than
1944 what is necessary to have a correct alignment in the object file.
1952 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1953 commands with different arguments. To allow the assembler to calculate the
1954 number of fill bytes in advance, the alignment of the segment must be a
1955 multiple of each of the alignment factors. This may result in unexpectedly
1956 large alignments for the segment within the module.
1967 For the assembler to be able to align correctly, the segment must be aligned
1968 to the least common multiple of 15 and 18 which is 90. The assembler will
1969 calculate this automatically and will mark the segment with this value.
1971 Unfortunately, the combined alignment may get rather large without the user
1972 knowing about it, wasting space in the final executable. If we add another
1973 alignment to the example above
1984 the assembler will force a segment alignment to the least common multiple of
1985 15, 18 and 251 - which is 22590. To protect the user against errors, the
1986 assembler will issue a warning when the combined alignment exceeds 256. The
1987 command line option <tt><ref id="option--large-alignment"
1988 name="--large-alignment"></tt> will disable this warning.
1990 Please note that with alignments that are a power of two (which were the
1991 only alignments possible in older versions of the assembler), the problem is
1992 less severe, because the least common multiple of powers to the same base is
1993 always the larger one.
1997 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1999 Define a string with a trailing zero.
2004 Msg: .asciiz "Hello world"
2007 This will put the string "Hello world" followed by a binary zero into
2008 the current segment. There may be more strings separated by commas, but
2009 the binary zero is only appended once (after the last one).
2012 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2014 Add an assertion. The command is followed by an expression, an action
2015 specifier, and an optional message that is output in case the assertion
2016 fails. If no message was given, the string "Assertion failed" is used. The
2017 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2018 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2019 assembler if possible, and in any case, it's also passed to the linker in
2020 the object file (if one is generated). The linker will then evaluate the
2021 expression when segment placement has been done.
2026 .assert * = $8000, error, "Code not at $8000"
2029 The example assertion will check that the current location is at $8000,
2030 when the output file is written, and abort with an error if this is not
2031 the case. More complex expressions are possible. The action specifier
2032 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2033 an error message. In the latter case, generation of the output file is
2034 suppressed in both the assembler and linker.
2037 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2039 Is followed by a plus or a minus character. When switched on (using a
2040 +), undefined symbols are automatically marked as import instead of
2041 giving errors. When switched off (which is the default so this does not
2042 make much sense), this does not happen and an error message is
2043 displayed. The state of the autoimport flag is evaluated when the
2044 complete source was translated, before outputting actual code, so it is
2045 <em/not/ possible to switch this feature on or off for separate sections
2046 of code. The last setting is used for all symbols.
2048 You should probably not use this switch because it delays error
2049 messages about undefined symbols until the link stage. The cc65
2050 compiler (which is supposed to produce correct assembler code in all
2051 circumstances, something which is not true for most assembler
2052 programmers) will insert this command to avoid importing each and every
2053 routine from the runtime library.
2058 .autoimport + ; Switch on auto import
2061 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2063 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2064 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2065 the operator '^' prepended to each expression in its list.
2070 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2072 TableLookupLo: .lobytes MyTable
2073 TableLookupHi: .hibytes MyTable
2074 TableLookupBank: .bankbytes MyTable
2077 which is equivalent to
2080 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2081 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2082 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2085 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2086 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2087 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2090 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2092 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2093 so this is a shortcut for
2099 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2102 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2104 Define byte sized data. Must be followed by a sequence of (byte ranged)
2105 expressions or strings.
2111 .byt "world", $0D, $00
2115 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2117 Switch on or off case sensitivity on identifiers. The default is off
2118 (that is, identifiers are case sensitive), but may be changed by the
2119 -i switch on the command line.
2120 The command must be followed by a '+' or '-' character to switch the
2121 option on or off respectively.
2126 .case - ; Identifiers are not case sensitive
2130 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2132 Apply a custom mapping for characters. The command is followed by two
2133 numbers. The first one is the index of the source character (range 1..255),
2134 the second one is the mapping (range 0..255). The mapping applies to all
2135 character and string constants when they generate output, and overrides a
2136 mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2137 command line switch.
2142 .charmap $41, $61 ; Map 'A' to 'a'
2146 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2148 Switch to the CODE segment. The name of the CODE segment is always
2149 "CODE", so this is a shortcut for
2155 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2158 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2160 Export a symbol and mark it in a special way. The linker is able to build
2161 tables of all such symbols. This may be used to automatically create a list
2162 of functions needed to initialize linked library modules.
2164 Note: The linker has a feature to build a table of marked routines, but it
2165 is your code that must call these routines, so just declaring a symbol with
2166 <tt/.CONDES/ does nothing by itself.
2168 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2169 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2170 is implied by <tt/.CONDES/.
2172 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2173 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2174 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2175 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2176 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2177 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2178 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2180 After the type, an optional priority may be specified. Higher numeric values
2181 mean higher priority. If no priority is given, the default priority of 7 is
2182 used. Be careful when assigning priorities to your own module constructors
2183 so they won't interfere with the ones in the cc65 library.
2188 .condes ModuleInit, constructor
2189 .condes ModInit, 0, 16
2192 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2193 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2194 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2195 name="Module constructors/destructors"> explaining the feature in more
2199 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2201 Export a symbol and mark it as a module constructor. This may be used
2202 together with the linker to build a table of constructor subroutines that
2203 are called by the startup code.
2205 Note: The linker has a feature to build a table of marked routines, but it
2206 is your code that must call these routines, so just declaring a symbol as
2207 constructor does nothing by itself.
2209 A constructor is always exported as an absolute (16 bit) symbol. You don't
2210 need to use an additional <tt/.export/ statement, this is implied by
2211 <tt/.constructor/. It may have an optional priority that is separated by a
2212 comma. Higher numeric values mean a higher priority. If no priority is
2213 given, the default priority of 7 is used. Be careful when assigning
2214 priorities to your own module constructors so they won't interfere with the
2215 ones in the cc65 library.
2220 .constructor ModuleInit
2221 .constructor ModInit, 16
2224 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2225 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2226 <ref id="condes" name="Module constructors/destructors"> explaining the
2227 feature in more detail.
2230 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2232 Switch to the DATA segment. The name of the DATA segment is always
2233 "DATA", so this is a shortcut for
2239 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2242 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2244 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2245 create word sized data in native 65XX format). Must be followed by a
2246 sequence of (word ranged) expressions.
2254 This will emit the bytes
2260 into the current segment in that order.
2263 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2265 Switch on or off debug info generation. The default is off (that is,
2266 the object file will not contain debug infos), but may be changed by the
2267 -g switch on the command line.
2268 The command must be followed by a '+' or '-' character to switch the
2269 option on or off respectively.
2274 .debuginfo + ; Generate debug info
2278 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2280 Start a define style macro definition. The command is followed by an
2281 identifier (the macro name) and optionally by a list of formal arguments
2284 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2285 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2288 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2289 section <ref id="macros" name="Macros">.
2292 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2294 Delete a classic macro (defined with <tt><ref id=".MACRO"
2295 name=".MACRO"></tt>) . The command is followed by the name of an
2296 existing macro. Its definition will be deleted together with the name.
2297 If necessary, another macro with this name may be defined later.
2299 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2300 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2301 <tt><ref id=".MACRO" name=".MACRO"></tt>
2303 See also section <ref id="macros" name="Macros">.
2306 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2308 Builtin function. The function expects an identifier as argument in braces.
2309 The argument is evaluated, and the function yields "true" if the identifier
2310 is a symbol that is already defined somewhere in the source file up to the
2311 current position. Otherwise the function yields false. As an example, the
2312 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2319 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2321 Export a symbol and mark it as a module destructor. This may be used
2322 together with the linker to build a table of destructor subroutines that
2323 are called by the startup code.
2325 Note: The linker has a feature to build a table of marked routines, but it
2326 is your code that must call these routines, so just declaring a symbol as
2327 constructor does nothing by itself.
2329 A destructor is always exported as an absolute (16 bit) symbol. You don't
2330 need to use an additional <tt/.export/ statement, this is implied by
2331 <tt/.destructor/. It may have an optional priority that is separated by a
2332 comma. Higher numerical values mean a higher priority. If no priority is
2333 given, the default priority of 7 is used. Be careful when assigning
2334 priorities to your own module destructors so they won't interfere with the
2335 ones in the cc65 library.
2340 .destructor ModuleDone
2341 .destructor ModDone, 16
2344 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2345 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2346 section <ref id="condes" name="Module constructors/destructors"> explaining
2347 the feature in more detail.
2350 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2352 Define dword sized data (4 bytes) Must be followed by a sequence of
2358 .dword $12344512, $12FA489
2362 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2364 Conditional assembly: Reverse the current condition.
2367 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2369 Conditional assembly: Reverse current condition and test a new one.
2372 <sect1><tt>.END</tt><label id=".END"><p>
2374 Forced end of assembly. Assembly stops at this point, even if the command
2375 is read from an include file.
2378 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2380 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2383 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2385 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2386 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2389 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2391 Marks the end of a macro definition.
2393 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2394 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2395 <tt><ref id=".MACRO" name=".MACRO"></tt>
2397 See also section <ref id="macros" name="Macros">.
2400 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2402 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2405 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2407 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2410 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2412 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2415 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2417 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2418 command and the separate section named <ref id="structs" name=""Structs
2422 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2424 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2425 command and the separate section named <ref id="structs" name=""Structs
2429 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2431 Start an enumeration. This directive is very similar to the C <tt/enum/
2432 keyword. If a name is given, a new scope is created for the enumeration,
2433 otherwise the enumeration members are placed in the enclosing scope.
2435 In the enumeration body, symbols are declared. The first symbol has a value
2436 of zero, and each following symbol will get the value of the preceding plus
2437 one. This behaviour may be overridden by an explicit assignment. Two symbols
2438 may have the same value.
2450 Above example will create a new scope named <tt/errorcodes/ with three
2451 symbols in it that get the values 0, 1 and 2 respectively. Another way
2452 to write this would have been:
2462 Please note that explicit scoping must be used to access the identifiers:
2465 .word errorcodes::no_error
2468 A more complex example:
2477 EWOULDBLOCK = EAGAIN
2481 In this example, the enumeration does not have a name, which means that the
2482 members will be visible in the enclosing scope and can be used in this scope
2483 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2484 The value for the following members is incremented by one, so <tt/EOK/ would
2485 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2486 override for the value using an already defined symbol.
2489 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2491 Force an assembly error. The assembler will output an error message
2492 preceded by "User error". Assembly is continued but no object file will
2495 This command may be used to check for initial conditions that must be
2496 set before assembling a source file.
2506 .error "Must define foo or bar!"
2510 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2511 <tt><ref id=".OUT" name=".OUT"></tt>,
2512 <tt><ref id=".WARNING" name=".WARNING"></tt>
2515 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2517 Abort a macro expansion immediately. This command is often useful in
2520 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2521 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2522 <tt><ref id=".MACRO" name=".MACRO"></tt>
2524 See also section <ref id="macros" name="Macros">.
2527 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2529 Make symbols accessible from other modules. Must be followed by a comma
2530 separated list of symbols to export, with each one optionally followed by an
2531 address specification and (also optional) an assignment. Using an additional
2532 assignment in the export statement allows to define and export a symbol in
2533 one statement. The default is to export the symbol with the address size it
2534 actually has. The assembler will issue a warning, if the symbol is exported
2535 with an address size smaller than the actual address size.
2542 .export foobar: far = foo * bar
2543 .export baz := foobar, zap: far = baz - bar
2546 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2549 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2552 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2554 Make symbols accessible from other modules. Must be followed by a comma
2555 separated list of symbols to export. The exported symbols are explicitly
2556 marked as zero page symbols. An assignment may be included in the
2557 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2564 .exportzp baz := $02
2567 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2570 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2572 Define far (24 bit) address data. The command must be followed by a
2573 sequence of (not necessarily constant) expressions.
2578 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2581 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2584 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2586 Force an assembly error and terminate assembly. The assembler will output an
2587 error message preceded by "User error" and will terminate assembly
2590 This command may be used to check for initial conditions that must be
2591 set before assembling a source file.
2601 .fatal "Must define foo or bar!"
2605 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2606 <tt><ref id=".OUT" name=".OUT"></tt>,
2607 <tt><ref id=".WARNING" name=".WARNING"></tt>
2610 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2612 This directive may be used to enable one or more compatibility features
2613 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2614 possible, it may be useful when porting sources written for other
2615 assemblers. There is no way to switch a feature off, once you have
2616 enabled it, so using
2622 will enable the feature until end of assembly is reached.
2624 The following features are available:
2628 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2630 Accept the at character (`@') as a valid character in identifiers. The
2631 at character is not allowed to start an identifier, even with this
2634 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2636 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2637 comment terminators. Note that C comments may not be nested. There's also a
2638 pitfall when using C like comments: All statements must be terminated by
2639 "end-of-line". Using C like comments, it is possible to hide the newline,
2640 which results in error messages. See the following non working example:
2643 lda #$00 /* This comment hides the newline
2647 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2649 Accept the dollar sign (`$') as a valid character in identifiers. The
2650 dollar character is not allowed to start an identifier, even with this
2653 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2655 The dollar sign may be used as an alias for the star (`*'), which
2656 gives the value of the current PC in expressions.
2657 Note: Assignment to the pseudo variable is not allowed.
2659 <tag><tt>force_range</tt><label id="force_range"></tag>
2661 Force expressions into their valid range for immediate addressing and
2662 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2663 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2664 since it will completely disable error checks.
2666 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2668 Allow labels without a trailing colon. These labels are only accepted,
2669 if they start at the beginning of a line (no leading white space).
2671 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2673 Accept the dot (`.') as the first character of an identifier. This may be
2674 used for example to create macro names that start with a dot emulating
2675 control directives of other assemblers. Note however, that none of the
2676 reserved keywords built into the assembler, that starts with a dot, may be
2677 overridden. When using this feature, you may also get into trouble if
2678 later versions of the assembler define new keywords starting with a dot.
2680 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2682 Accept single quotes as well as double quotes as terminators for char
2685 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2687 Accept single quotes as well as double quotes as terminators for string
2690 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2692 Accept single quoted character constants where the terminating quote is
2697 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2698 loose_string_term/, since in this case the input would be ambiguous.
2700 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2702 This feature makes relocatable/absolute mode local to the current segment.
2703 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2704 effect will only enable absolute mode for the current segment. Dito for
2705 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2707 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2709 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2710 is enabled). Such an assignment is handled identical to the <tt><ref
2711 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2712 removing the lines with the assignments may also be an option when porting
2713 code written for older assemblers).
2715 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2717 Allow the use of instructions names as names for macros and symbols. This
2718 makes it possible to "overload" instructions by defining a macro with the
2719 same name. This does also make it possible to introduce hard to find errors
2720 in your code, so be careful!
2722 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2724 Allow underlines within numeric constants. These may be used for grouping
2725 the digits of numbers for easier reading.
2728 .feature underline_in_numbers
2729 .word %1100001110100101
2730 .word %1100_0011_1010_0101 ; Identical but easier to read
2735 It is also possible to specify features on the command line using the
2736 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2737 This is useful when translating sources written for older assemblers, when
2738 you don't want to change the source code.
2740 As an example, to translate sources written for Andre Fachats xa65
2741 assembler, the features
2744 labels_without_colons, pc_assignment, loose_char_term
2747 may be helpful. They do not make ca65 completely compatible, so you may not
2748 be able to translate the sources without changes, even when enabling these
2749 features. However, I have found several sources that translate without
2750 problems when enabling these features on the command line.
2753 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2755 Insert an option string into the object file. There are two forms of
2756 this command, one specifies the option by a keyword, the second
2757 specifies it as a number. Since usage of the second one needs knowledge
2758 of the internal encoding, its use is not recommended and I will only
2759 describe the first form here.
2761 The command is followed by one of the keywords
2769 a comma and a string. The option is written into the object file
2770 together with the string value. This is currently unidirectional and
2771 there is no way to actually use these options once they are in the
2777 .fileopt comment, "Code stolen from my brother"
2778 .fileopt compiler, "BASIC 2.0"
2779 .fopt author, "J. R. User"
2783 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2785 Import an absolute symbol from another module. The command is followed by a
2786 comma separated list of symbols to import. The command is similar to <tt>
2787 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2788 written to the generated object file, even if the symbol is never referenced
2789 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2790 references for unused symbols).
2795 .forceimport needthisone, needthistoo
2798 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2801 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2803 Declare symbols as global. Must be followed by a comma separated list of
2804 symbols to declare. Symbols from the list, that are defined somewhere in the
2805 source, are exported, all others are imported. Additional <tt><ref
2806 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2807 name=".EXPORT"></tt> commands for the same symbol are allowed.
2816 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2818 Declare symbols as global. Must be followed by a comma separated list of
2819 symbols to declare. Symbols from the list, that are defined somewhere in the
2820 source, are exported, all others are imported. Additional <tt><ref
2821 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2822 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2823 in the list are explicitly marked as zero page symbols.
2831 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2833 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2834 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2835 the operator '>' prepended to each expression in its list.
2840 .lobytes $1234, $2345, $3456, $4567
2841 .hibytes $fedc, $edcb, $dcba, $cba9
2844 which is equivalent to
2847 .byte $34, $45, $56, $67
2848 .byte $fe, $ed, $dc, $cb
2854 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2856 TableLookupLo: .lobytes MyTable
2857 TableLookupHi: .hibytes MyTable
2860 which is equivalent to
2863 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2864 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2867 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2868 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2869 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2872 <sect1><tt>.I16</tt><label id=".I16"><p>
2874 Valid only in 65816 mode. Switch the index registers to 16 bit.
2876 Note: This command will not emit any code, it will tell the assembler to
2877 create 16 bit operands for immediate operands.
2879 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2880 name=".SMART"></tt> commands.
2883 <sect1><tt>.I8</tt><label id=".I8"><p>
2885 Valid only in 65816 mode. Switch the index registers to 8 bit.
2887 Note: This command will not emit any code, it will tell the assembler to
2888 create 8 bit operands for immediate operands.
2890 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2891 name=".SMART"></tt> commands.
2894 <sect1><tt>.IF</tt><label id=".IF"><p>
2896 Conditional assembly: Evaluate an expression and switch assembler output
2897 on or off depending on the expression. The expression must be a constant
2898 expression, that is, all operands must be defined.
2900 A expression value of zero evaluates to FALSE, any other value evaluates
2904 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2906 Conditional assembly: Check if there are any remaining tokens in this line,
2907 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2908 condition is not true, further lines are not assembled until an <tt><ref
2909 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2910 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2912 This command is often used to check if a macro parameter was given. Since an
2913 empty macro parameter will evaluate to nothing, the condition will evaluate
2914 to TRUE if an empty parameter was given.
2928 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2931 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2933 Conditional assembly: Evaluate an expression and switch assembler output
2934 on or off depending on the constness of the expression.
2936 A const expression evaluates to to TRUE, a non const expression (one
2937 containing an imported or currently undefined symbol) evaluates to
2940 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2943 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2945 Conditional assembly: Check if a symbol is defined. Must be followed by
2946 a symbol name. The condition is true if the the given symbol is already
2947 defined, and false otherwise.
2949 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2952 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2954 Conditional assembly: Check if there are any remaining tokens in this line,
2955 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2956 condition is not true, further lines are not assembled until an <tt><ref
2957 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2958 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2960 This command is often used to check if a macro parameter was given.
2961 Since an empty macro parameter will evaluate to nothing, the condition
2962 will evaluate to FALSE if an empty parameter was given.
2975 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2978 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2980 Conditional assembly: Check if a symbol is defined. Must be followed by
2981 a symbol name. The condition is true if the the given symbol is not
2982 defined, and false otherwise.
2984 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2987 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2989 Conditional assembly: Check if a symbol is referenced. Must be followed
2990 by a symbol name. The condition is true if if the the given symbol was
2991 not referenced before, and false otherwise.
2993 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2996 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2998 Conditional assembly: Check if the assembler is currently in 6502 mode
2999 (see <tt><ref id=".P02" name=".P02"></tt> command).
3002 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
3004 Conditional assembly: Check if the assembler is currently in 65816 mode
3005 (see <tt><ref id=".P816" name=".P816"></tt> command).
3008 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
3010 Conditional assembly: Check if the assembler is currently in 65C02 mode
3011 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3014 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3016 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3017 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3020 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3022 Conditional assembly: Check if a symbol is referenced. Must be followed
3023 by a symbol name. The condition is true if if the the given symbol was
3024 referenced before, and false otherwise.
3026 This command may be used to build subroutine libraries in include files
3027 (you may use separate object modules for this purpose too).
3032 .ifref ToHex ; If someone used this subroutine
3033 ToHex: tay ; Define subroutine
3039 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3042 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3044 Import a symbol from another module. The command is followed by a comma
3045 separated list of symbols to import, with each one optionally followed by
3046 an address specification.
3052 .import bar: zeropage
3055 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3058 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3060 Import a symbol from another module. The command is followed by a comma
3061 separated list of symbols to import. The symbols are explicitly imported
3062 as zero page symbols (that is, symbols with values in byte range).
3070 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3073 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3075 Include a file as binary data. The command expects a string argument
3076 that is the name of a file to include literally in the current segment.
3077 In addition to that, a start offset and a size value may be specified,
3078 separated by commas. If no size is specified, all of the file from the
3079 start offset to end-of-file is used. If no start position is specified
3080 either, zero is assumed (which means that the whole file is inserted).
3085 ; Include whole file
3086 .incbin "sprites.dat"
3088 ; Include file starting at offset 256
3089 .incbin "music.dat", $100
3091 ; Read 100 bytes starting at offset 200
3092 .incbin "graphics.dat", 200, 100
3096 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3098 Include another file. Include files may be nested up to a depth of 16.
3107 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3109 Export a symbol and mark it as an interruptor. This may be used together
3110 with the linker to build a table of interruptor subroutines that are called
3113 Note: The linker has a feature to build a table of marked routines, but it
3114 is your code that must call these routines, so just declaring a symbol as
3115 interruptor does nothing by itself.
3117 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3118 need to use an additional <tt/.export/ statement, this is implied by
3119 <tt/.interruptor/. It may have an optional priority that is separated by a
3120 comma. Higher numeric values mean a higher priority. If no priority is
3121 given, the default priority of 7 is used. Be careful when assigning
3122 priorities to your own module constructors so they won't interfere with the
3123 ones in the cc65 library.
3128 .interruptor IrqHandler
3129 .interruptor Handler, 16
3132 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3133 section <ref id="condes" name="Module constructors/destructors"> explaining
3134 the feature in more detail.
3137 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3139 Switch on or off line continuations using the backslash character
3140 before a newline. The option is off by default.
3141 Note: Line continuations do not work in a comment. A backslash at the
3142 end of a comment is treated as part of the comment and does not trigger
3144 The command must be followed by a '+' or '-' character to switch the
3145 option on or off respectively.
3150 .linecont + ; Allow line continuations
3153 #$20 ; This is legal now
3157 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3159 Enable output to the listing. The command must be followed by a boolean
3160 switch ("on", "off", "+" or "-") and will enable or disable listing
3162 The option has no effect if the listing is not enabled by the command line
3163 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3164 to the listing file, if the counter is greater than zero, and suppressed if
3165 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3171 .list on ; Enable listing output
3175 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3177 Set, how many bytes are shown in the listing for one source line. The
3178 default is 12, so the listing will show only the first 12 bytes for any
3179 source line that generates more than 12 bytes of code or data.
3180 The directive needs an argument, which is either "unlimited", or an
3181 integer constant in the range 4..255.
3186 .listbytes unlimited ; List all bytes
3187 .listbytes 12 ; List the first 12 bytes
3188 .incbin "data.bin" ; Include large binary file
3192 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3194 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3195 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3196 the operator '<' prepended to each expression in its list.
3201 .lobytes $1234, $2345, $3456, $4567
3202 .hibytes $fedc, $edcb, $dcba, $cba9
3205 which is equivalent to
3208 .byte $34, $45, $56, $67
3209 .byte $fe, $ed, $dc, $cb
3215 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3217 TableLookupLo: .lobytes MyTable
3218 TableLookupHi: .hibytes MyTable
3221 which is equivalent to
3224 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3225 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3228 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3229 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3230 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3233 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3235 This command may only be used inside a macro definition. It declares a
3236 list of identifiers as local to the macro expansion.
3238 A problem when using macros are labels: Since they don't change their name,
3239 you get a "duplicate symbol" error if the macro is expanded the second time.
3240 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3241 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3244 Some other assemblers start a new lexical block inside a macro expansion.
3245 This has some drawbacks however, since that will not allow <em/any/ symbol
3246 to be visible outside a macro, a feature that is sometimes useful. The
3247 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3248 to address the problem.
3250 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3254 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3256 Defines the character that start "cheap" local labels. You may use one
3257 of '@' and '?' as start character. The default is '@'.
3259 Cheap local labels are labels that are visible only between two non
3260 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3261 using explicit lexical nesting.
3268 Clear: lda #$00 ; Global label
3269 ?Loop: sta Mem,y ; Local label
3273 Sub: ... ; New global label
3274 bne ?Loop ; ERROR: Unknown identifier!
3278 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3280 Insert a predefined macro package. The command is followed by an
3281 identifier specifying the macro package to insert. Available macro
3285 atari Defines the scrcode macro.
3286 cbm Defines the scrcode macro.
3287 cpu Defines constants for the .CPU variable.
3288 generic Defines generic macros like add and sub.
3289 longbranch Defines conditional long jump macros.
3292 Including a macro package twice, or including a macro package that
3293 redefines already existing macros will lead to an error.
3298 .macpack longbranch ; Include macro package
3300 cmp #$20 ; Set condition codes
3301 jne Label ; Jump long on condition
3304 Macro packages are explained in more detail in section <ref
3305 id="macropackages" name="Macro packages">.
3308 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3310 Start a classic macro definition. The command is followed by an identifier
3311 (the macro name) and optionally by a comma separated list of identifiers
3312 that are macro parameters. A macro definition is terminated by <tt><ref
3313 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3318 .macro ldax arg ; Define macro ldax
3323 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3324 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3325 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3327 See also section <ref id="macros" name="Macros">.
3330 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3332 Start a section of absolute code. The command is followed by a constant
3333 expression that gives the new PC counter location for which the code is
3334 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3337 By default, absolute/relocatable mode is global (valid even when switching
3338 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3339 it can be made segment local.
3341 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3342 code at a specific address is the job of the linker, not the assembler, so
3343 there is usually no reason to assemble code to a specific address.
3348 .org $7FF ; Emit code starting at $7FF
3352 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3354 Output a string to the console without producing an error. This command
3355 is similar to <tt/.ERROR/, however, it does not force an assembler error
3356 that prevents the creation of an object file.
3361 .out "This code was written by the codebuster(tm)"
3364 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3365 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3366 <tt><ref id=".WARNING" name=".WARNING"></tt>
3369 <sect1><tt>.P02</tt><label id=".P02"><p>
3371 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3372 instructions. This is the default if not overridden by the
3373 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3375 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3376 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3379 <sect1><tt>.P816</tt><label id=".P816"><p>
3381 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3382 6502 instruction sets.
3384 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3385 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3388 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3390 Set the page length for the listing. Must be followed by an integer
3391 constant. The value may be "unlimited", or in the range 32 to 127. The
3392 statement has no effect if no listing is generated. The default value is -1
3393 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3394 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3395 after assembly is complete, you cannot use multiple line lengths with one
3396 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3401 .pagelength 66 ; Use 66 lines per listing page
3403 .pagelength unlimited ; Unlimited page length
3407 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3409 Enable the 65C02 instructions set. This instruction set includes all
3410 6502 and 65SC02 instructions.
3412 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3413 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3416 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3418 Pop the last CPU setting from the stack, and activate it.
3420 This command will switch back to the CPU that was last pushed onto the CPU
3421 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3422 remove this entry from the stack.
3424 The assembler will print an error message if the CPU stack is empty when
3425 this command is issued.
3427 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3428 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3431 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3433 Pop the last pushed segment from the stack, and set it.
3435 This command will switch back to the segment that was last pushed onto the
3436 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3437 command, and remove this entry from the stack.
3439 The assembler will print an error message if the segment stack is empty
3440 when this command is issued.
3442 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3445 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3447 Start a nested lexical level with the given name and adds a symbol with this
3448 name to the enclosing scope. All new symbols from now on are in the local
3449 lexical level and are accessible from outside only via <ref id="scopesyntax"
3450 name="explicit scope specification">. Symbols defined outside this local
3451 level may be accessed as long as their names are not used for new symbols
3452 inside the level. Symbols names in other lexical levels do not clash, so you
3453 may use the same names for identifiers. The lexical level ends when the
3454 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3455 may be nested up to a depth of 16 (this is an artificial limit to protect
3456 against errors in the source).
3458 Note: Macro names are always in the global level and in a separate name
3459 space. There is no special reason for this, it's just that I've never
3460 had any need for local macro definitions.
3465 .proc Clear ; Define Clear subroutine, start new level
3467 L1: sta Mem,y ; L1 is local and does not cause a
3468 ; duplicate symbol error if used in other
3471 bne L1 ; Reference local symbol
3473 .endproc ; Leave lexical level
3476 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3480 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3482 Enable the 65SC02 instructions set. This instruction set includes all
3485 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3486 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3489 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3491 Push the currently active CPU onto a stack. The stack has a size of 8
3494 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3495 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3496 later, without knowledge of the current CPU setting.
3498 The assembler will print an error message if the CPU stack is already full,
3499 when this command is issued.
3501 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3502 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3505 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3507 Push the currently active segment onto a stack. The entries on the stack
3508 include the name of the segment and the segment type. The stack has a size
3511 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3512 to switch to another segment and to restore the old segment later, without
3513 even knowing the name and type of the current segment.
3515 The assembler will print an error message if the segment stack is already
3516 full, when this command is issued.
3518 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3521 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3523 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3524 name=".ORG"></tt> command.
3527 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3529 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3530 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3531 a constant expression that tells how many times the commands in the body
3532 should get repeated. Optionally, a comma and an identifier may be specified.
3533 If this identifier is found in the body of the repeat statement, it is
3534 replaced by the current repeat count (starting with zero for the first time
3535 the body is repeated).
3537 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3538 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3539 level will be used, not the one from the outer level.
3543 The following macro will emit a string that is "encrypted" in that all
3544 characters of the string are XORed by the value $55.
3548 .repeat .strlen(Arg), I
3549 .byte .strat(Arg, I) ^ $55
3554 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3557 <sect1><tt>.RES</tt><label id=".RES"><p>
3559 Reserve storage. The command is followed by one or two constant
3560 expressions. The first one is mandatory and defines, how many bytes of
3561 storage should be defined. The second, optional expression must by a
3562 constant byte value that will be used as value of the data. If there
3563 is no fill value given, the linker will use the value defined in the
3564 linker configuration file (default: zero).
3569 ; Reserve 12 bytes of memory with value $AA
3574 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3576 Switch to the RODATA segment. The name of the RODATA segment is always
3577 "RODATA", so this is a shortcut for
3583 The RODATA segment is a segment that is used by the compiler for
3584 readonly data like string constants.
3586 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3589 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3591 Start a nested lexical level with the given name. All new symbols from now
3592 on are in the local lexical level and are accessible from outside only via
3593 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3594 outside this local level may be accessed as long as their names are not used
3595 for new symbols inside the level. Symbols names in other lexical levels do
3596 not clash, so you may use the same names for identifiers. The lexical level
3597 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3598 read. Lexical levels may be nested up to a depth of 16 (this is an
3599 artificial limit to protect against errors in the source).
3601 Note: Macro names are always in the global level and in a separate name
3602 space. There is no special reason for this, it's just that I've never
3603 had any need for local macro definitions.
3608 .scope Error ; Start new scope named Error
3610 File = 1 ; File error
3611 Parse = 2 ; Parse error
3612 .endscope ; Close lexical level
3615 lda #Error::File ; Use symbol from scope Error
3618 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3622 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3624 Switch to another segment. Code and data is always emitted into a
3625 segment, that is, a named section of data. The default segment is
3626 "CODE". There may be up to 254 different segments per object file
3627 (and up to 65534 per executable). There are shortcut commands for
3628 the most common segments ("CODE", "DATA" and "BSS").
3630 The command is followed by a string containing the segment name (there are
3631 some constraints for the name - as a rule of thumb use only those segment
3632 names that would also be valid identifiers). There may also be an optional
3633 address size separated by a colon. See the section covering <tt/<ref
3634 id="address-sizes" name="address sizes">/ for more information.
3636 The default address size for a segment depends on the memory model specified
3637 on the command line. The default is "absolute", which means that you don't
3638 have to use an address size modifier in most cases.
3640 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3641 That is, the segment will reside somewhere in core memory outside the zero
3642 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3643 page and direct (short) addressing is possible for data in this segment.
3645 Beware: Only labels in a segment with the zeropage attribute are marked
3646 as reachable by short addressing. The `*' (PC counter) operator will
3647 work as in other segments and will create absolute variable values.
3649 Please note that a segment cannot have two different address sizes. A
3650 segment specified as zeropage cannot be declared as being absolute later.
3655 .segment "ROM2" ; Switch to ROM2 segment
3656 .segment "ZP2": zeropage ; New direct segment
3657 .segment "ZP2" ; Ok, will use last attribute
3658 .segment "ZP2": absolute ; Error, redecl mismatch
3661 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3662 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3663 id=".RODATA" name=".RODATA"></tt>
3666 <sect1><tt>.SET</tt><label id=".SET"><p>
3668 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3669 name="Numeric variables"> for a full description.
3672 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3674 Switch the CPU instruction set. The command is followed by a string that
3675 specifies the CPU. Possible values are those that can also be supplied to
3676 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3677 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3678 note that support for the sunplus CPU is not available in the freeware
3679 version, because the instruction set of the sunplus CPU is "proprietary
3682 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3683 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3684 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3685 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3686 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3687 <tt><ref id=".P02" name=".P02"></tt>,
3688 <tt><ref id=".P816" name=".P816"></tt>,
3689 <tt><ref id=".PC02" name=".PC02"></tt>,
3690 <tt><ref id=".PSC02" name=".PSC02"></tt>
3693 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3695 Switch on or off smart mode. The command must be followed by a '+' or '-'
3696 character to switch the option on or off respectively. The default is off
3697 (that is, the assembler doesn't try to be smart), but this default may be
3698 changed by the -s switch on the command line.
3700 In smart mode the assembler will do the following:
3703 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3704 and update the operand sizes accordingly. If the operand of such an
3705 instruction cannot be evaluated by the assembler (for example, because
3706 the operand is an imported symbol), a warning is issued. Beware: Since
3707 the assembler cannot trace the execution flow this may lead to false
3708 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3709 instructions to tell the assembler about the current settings.
3710 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3711 used within a procedure declared as <tt/far/, or if the procedure has
3712 no explicit address specification, but it is <tt/far/ because of the
3720 .smart - ; Stop being smart
3723 See: <tt><ref id=".A16" name=".A16"></tt>,
3724 <tt><ref id=".A8" name=".A8"></tt>,
3725 <tt><ref id=".I16" name=".I16"></tt>,
3726 <tt><ref id=".I8" name=".I8"></tt>
3729 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3731 Starts a struct definition. Structs are covered in a separate section named
3732 <ref id="structs" name=""Structs and unions"">.
3734 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3735 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3736 <tt><ref id=".UNION" name=".UNION"></tt>
3739 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3741 Enable the SunPlus instructions set. This command will not work in the
3742 freeware version of the assembler, because the instruction set is
3743 "proprietary and confidential".
3745 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3746 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3747 <tt><ref id=".P816" name=".P816"></tt>
3750 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3752 Allocate space for a struct or union.
3763 .tag Point ; Allocate 4 bytes
3767 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3769 Delete a define style macro definition. The command is followed by an
3770 identifier which specifies the name of the macro to delete. Macro
3771 replacement is switched of when reading the token following the command
3772 (otherwise the macro name would be replaced by its replacement list).
3774 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3775 section <ref id="macros" name="Macros">.
3778 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3780 Starts a union definition. Unions are covered in a separate section named
3781 <ref id="structs" name=""Structs and unions"">.
3783 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3784 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3785 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3788 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3790 Force an assembly warning. The assembler will output a warning message
3791 preceded by "User warning". This warning will always be output, even if
3792 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3793 command line option.
3795 This command may be used to output possible problems when assembling
3804 .warning "Forward jump in jne, cannot optimize!"
3814 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3815 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3816 <tt><ref id=".OUT" name=".OUT"></tt>
3819 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3821 Define word sized data. Must be followed by a sequence of (word ranged,
3822 but not necessarily constant) expressions.
3827 .word $0D00, $AF13, _Clear
3831 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3833 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3834 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3838 .segment "ZEROPAGE", zeropage
3841 Because of the "zeropage" attribute, labels declared in this segment are
3842 addressed using direct addressing mode if possible. You <em/must/ instruct
3843 the linker to place this segment somewhere in the address range 0..$FF
3844 otherwise you will get errors.
3846 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3850 <sect>Macros<label id="macros"><p>
3853 <sect1>Introduction<p>
3855 Macros may be thought of as "parametrized super instructions". Macros are
3856 sequences of tokens that have a name. If that name is used in the source
3857 file, the macro is "expanded", that is, it is replaced by the tokens that
3858 were specified when the macro was defined.
3861 <sect1>Macros without parameters<p>
3863 In its simplest form, a macro does not have parameters. Here's an
3867 .macro asr ; Arithmetic shift right
3868 cmp #$80 ; Put bit 7 into carry
3869 ror ; Rotate right with carry
3873 The macro above consists of two real instructions, that are inserted into
3874 the code, whenever the macro is expanded. Macro expansion is simply done
3875 by using the name, like this:
3884 <sect1>Parametrized macros<p>
3886 When using macro parameters, macros can be even more useful:
3900 When calling the macro, you may give a parameter, and each occurrence of
3901 the name "addr" in the macro definition will be replaced by the given
3920 A macro may have more than one parameter, in this case, the parameters
3921 are separated by commas. You are free to give less parameters than the
3922 macro actually takes in the definition. You may also leave intermediate
3923 parameters empty. Empty parameters are replaced by empty space (that is,
3924 they are removed when the macro is expanded). If you have a look at our
3925 macro definition above, you will see, that replacing the "addr" parameter
3926 by nothing will lead to wrong code in most lines. To help you, writing
3927 macros with a variable parameter list, there are some control commands:
3929 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3930 returns true, if there are any tokens on the remainder of the line. Since
3931 empty parameters are replaced by nothing, this may be used to test if a given
3932 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3935 Look at this example:
3938 .macro ldaxy a, x, y
3951 This macro may be called as follows:
3954 ldaxy 1, 2, 3 ; Load all three registers
3956 ldaxy 1, , 3 ; Load only a and y
3958 ldaxy , , 3 ; Load y only
3961 There's another helper command for determining, which macro parameters are
3962 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3963 replaced by the parameter count given, <em/including/ intermediate empty macro
3967 ldaxy 1 ; .PARAMCOUNT = 1
3968 ldaxy 1,,3 ; .PARAMCOUNT = 3
3969 ldaxy 1,2 ; .PARAMCOUNT = 2
3970 ldaxy 1, ; .PARAMCOUNT = 2
3971 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3974 Macro parameters may optionally be enclosed into curly braces. This allows the
3975 inclusion of tokens that would otherwise terminate the parameter (the comma in
3976 case of a macro parameter).
3979 .macro foo arg1, arg2
3983 foo ($00,x) ; Two parameters passed
3984 foo {($00,x)} ; One parameter passed
3987 In the first case, the macro is called with two parameters: '<tt/($00/'
3988 and 'x)'. The comma is not passed to the macro, since it is part of the
3989 calling sequence, not the parameters.
3991 In the second case, '($00,x)' is passed to the macro, this time
3992 including the comma.
3995 <sect1>Detecting parameter types<p>
3997 Sometimes it is nice to write a macro that acts differently depending on the
3998 type of the argument supplied. An example would be a macro that loads a 16 bit
3999 value from either an immediate operand, or from memory. The <tt/<ref
4000 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
4001 functions will allow you to do exactly this:
4005 .if (.match (.left (1, {arg}), #))
4007 lda #<(.right (.tcount ({arg})-1, {arg}))
4008 ldx #>(.right (.tcount ({arg})-1, {arg}))
4010 ; assume absolute or zero page
4017 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4018 check if its argument begins with a hash mark. If so, two immediate loads are
4019 emitted, Otherwise a load from an absolute zero page memory location is
4020 assumed. Please note how the curly braces are used to enclose parameters to
4021 pseudo functions handling token lists. This is necessary, because the token
4022 lists may include commas or parens, which would be treated by the assembler
4025 The macro can be used as
4030 ldax #$1234 ; X=$12, A=$34
4032 ldax foo ; X=$56, A=$78
4036 <sect1>Recursive macros<p>
4038 Macros may be used recursively:
4041 .macro push r1, r2, r3
4050 There's also a special macro to help writing recursive macros: <tt><ref
4051 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
4055 .macro push r1, r2, r3, r4, r5, r6, r7
4057 ; First parameter is empty
4063 push r2, r3, r4, r5, r6, r7
4067 When expanding this macro, the expansion will push all given parameters
4068 until an empty one is encountered. The macro may be called like this:
4071 push $20, $21, $32 ; Push 3 ZP locations
4072 push $21 ; Push one ZP location
4076 <sect1>Local symbols inside macros<p>
4078 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4079 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4080 Have a look at the inc16 macro above. Here is it again:
4094 If you have a closer look at the code, you will notice, that it could be
4095 written more efficiently, like this:
4106 But imagine what happens, if you use this macro twice? Since the label "Skip"
4107 has the same name both times, you get a "duplicate symbol" error. Without a
4108 way to circumvent this problem, macros are not as useful, as they could be.
4109 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4110 It declares one or more symbols as local to the macro expansion. The names of
4111 local variables are replaced by a unique name in each separate macro
4112 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4116 .local Skip ; Make Skip a local symbol
4120 Skip: ; Not visible outside
4124 Another solution is of course to start a new lexical block inside the macro
4125 that hides any labels:
4139 <sect1>C style macros<p>
4141 Starting with version 2.5 of the assembler, there is a second macro type
4142 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4143 similar to the classic macro type described above, but behaviour is sometimes
4148 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4149 span more than a line. You may use line continuation (see <tt><ref
4150 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4151 more than one line for increased readability, but the macro itself
4152 may not contain an end-of-line token.
4154 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4155 the name space with classic macros, but they are detected and replaced
4156 at the scanner level. While classic macros may be used in every place,
4157 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4158 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4159 they are more versatile in some situations.
4161 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4162 parameters. While classic macros may have empty parameters, this is
4163 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4164 For this macro type, the number of actual parameters must match
4165 exactly the number of formal parameters.
4167 To make this possible, formal parameters are enclosed in braces when
4168 defining the macro. If there are no parameters, the empty braces may
4171 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4172 contain end-of-line tokens, there are things that cannot be done. They
4173 may not contain several processor instructions for example. So, while
4174 some things may be done with both macro types, each type has special
4175 usages. The types complement each other.
4179 Let's look at a few examples to make the advantages and disadvantages
4182 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4183 following <tt/.DEFINE/:
4188 foo EQU $1234 ; This is accepted now
4191 You may use the directive to define string constants used elsewhere:
4194 ; Define the version number
4195 .define VERSION "12.3a"
4201 Macros with parameters may also be useful:
4204 .define DEBUG(message) .out message
4206 DEBUG "Assembling include file #3"
4209 Note that, while formal parameters have to be placed in braces, this is
4210 not true for the actual parameters. Beware: Since the assembler cannot
4211 detect the end of one parameter, only the first token is used. If you
4212 don't like that, use classic macros instead:
4215 .macro DEBUG message
4220 (This is an example where a problem can be solved with both macro types).
4223 <sect1>Characters in macros<p>
4225 When using the <ref id="option-t" name="-t"> option, characters are translated
4226 into the target character set of the specific machine. However, this happens
4227 as late as possible. This means that strings are translated if they are part
4228 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4229 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4230 used as part of an expression.
4232 This behaviour is very intuitive outside of macros but may be confusing when
4233 doing more complex macros. If you compare characters against numeric values,
4234 be sure to take the translation into account.
4237 <sect1>Deleting macros<p>
4239 Macros can be deleted. This will not work if the macro that should be deleted
4240 is currently expanded as in the following non working example:
4244 .delmacro notworking
4247 notworking ; Will not work
4250 The commands to delete classic and define style macros differ. Classic macros
4251 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4252 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4253 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4261 .byte value ; Emit one byte with value 1
4262 mac ; Emit another byte with value 2
4267 .byte value ; Error: Unknown identifier
4268 mac ; Error: Missing ":"
4271 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4272 the name of such a macro is replaced by its replacement list on a very low
4273 level. To get the actual name, macro replacement has to be switched off when
4274 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4275 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4276 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4277 different commands increases flexibility.
4280 <sect>Macro packages<label id="macropackages"><p>
4282 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4283 macro packages may be included with just one command. Available macro packages
4287 <sect1><tt>.MACPACK generic</tt><p>
4289 This macro package defines macros that are useful in almost any program.
4290 Currently defined macros are:
4325 <sect1><tt>.MACPACK longbranch</tt><p>
4327 This macro package defines long conditional jumps. They are named like the
4328 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4329 definition for the "<tt/jeq/" macro, the other macros are built using the same
4334 .if .def(Target) .and ((*+2)-(Target) <= 127)
4343 All macros expand to a short branch, if the label is already defined (back
4344 jump) and is reachable with a short jump. Otherwise the macro expands to a
4345 conditional branch with the branch condition inverted, followed by an absolute
4346 jump to the actual branch target.
4348 The package defines the following macros:
4351 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4356 <sect1><tt>.MACPACK atari</tt><p>
4358 The atari macro package will define a macro named <tt/scrcode/. It takes a
4359 string as argument and places this string into memory translated into screen
4363 <sect1><tt>.MACPACK cbm</tt><p>
4365 The cbm macro package will define a macro named <tt/scrcode/. It takes a
4366 string as argument and places this string into memory translated into screen
4370 <sect1><tt>.MACPACK cpu</tt><p>
4372 This macro package does not define any macros but constants used to examine
4373 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4374 each supported CPU a constant similar to
4386 is defined. These constants may be used to determine the exact type of the
4387 currently enabled CPU. In addition to that, for each CPU instruction set,
4388 another constant is defined:
4400 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4401 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4402 currently enabled CPU supports a specific instruction set. For example the
4403 65C02 supports all instructions of the 65SC02 CPU, so it has the
4404 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4408 .if (.cpu .bitand CPU_ISET_65SC02)
4416 it is possible to determine if the
4422 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4423 CPUs (the latter two are upwards compatible to the 65SC02).
4427 <sect>Predefined constants<label id="predefined-constants"><p>
4429 For better orthogonality, the assembler defines similar symbols as the
4430 compiler, depending on the target system selected:
4433 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
4434 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4435 <item><tt/__ATARI__/ - Target system is <tt/atari/
4436 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4437 <item><tt/__BBC__/ - Target system is <tt/bbc/
4438 <item><tt/__C128__/ - Target system is <tt/c128/
4439 <item><tt/__C16__/ - Target system is <tt/c16/
4440 <item><tt/__C64__/ - Target system is <tt/c64/
4441 <item><tt/__CBM__/ - Target is a Commodore system
4442 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4443 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4444 <item><tt/__GEOS__/ - Target system is <tt/geos/
4445 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4446 <item><tt/__NES__/ - Target system is <tt/nes/
4447 <item><tt/__PET__/ - Target system is <tt/pet/
4448 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4449 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4450 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4454 <sect>Structs and unions<label id="structs"><p>
4456 <sect1>Structs and unions Overview<p>
4458 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4459 are to some degree comparable to their C counterparts. Both have a list of
4460 members. Each member allocates storage and may optionally have a name, which,
4461 in case of a struct, is the offset from the beginning and, in case of a union,
4465 <sect1>Declaration<p>
4467 Here is an example for a very simple struct with two members and a total size
4477 A union shares the total space between all its members, its size is the same
4478 as that of the largest member. The offset of all members relative to the union
4488 A struct or union must not necessarily have a name. If it is anonymous, no
4489 local scope is opened, the identifiers used to name the members are placed
4490 into the current scope instead.
4492 A struct may contain unnamed members and definitions of local structs. The
4493 storage allocators may contain a multiplier, as in the example below:
4498 .word 2 ; Allocate two words
4505 <sect1>The <tt/.TAG/ keyword<p>
4507 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4508 for an already defined struct or unions within another struct:
4522 Space for a struct or union may be allocated using the <ref id=".TAG"
4523 name=".TAG"> directive.
4529 Currently, members are just offsets from the start of the struct or union. To
4530 access a field of a struct, the member offset has to be added to the address
4531 of the struct itself:
4534 lda C+Circle::Radius ; Load circle radius into A
4537 This may change in a future version of the assembler.
4540 <sect1>Limitations<p>
4542 Structs and unions are currently implemented as nested symbol tables (in fact,
4543 they were a by-product of the improved scoping rules). Currently, the
4544 assembler has no idea of types. This means that the <ref id=".TAG"
4545 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4546 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4547 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4548 this structure accessible by using the '::' operator.
4552 <sect>Module constructors/destructors<label id="condes"><p>
4554 <em>Note:</em> This section applies mostly to C programs, so the explanation
4555 below uses examples from the C libraries. However, the feature may also be
4556 useful for assembler programs.
4559 <sect1>Module constructors/destructors Overview<p>
4561 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4562 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4563 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4564 special way. The linker is able to generate tables with all functions of a
4565 specific type. Such a table will <em>only</em> include symbols from object
4566 files that are linked into a specific executable. This may be used to add
4567 initialization and cleanup code for library modules, or a table of interrupt
4570 The C heap functions are an example where module initialization code is used.
4571 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4572 variables that contain the start and the end of the heap, pointers to the free
4573 list and so on. Since the end of the heap depends on the size and start of the
4574 stack, it must be initialized at runtime. However, initializing these
4575 variables for programs that do not use the heap are a waste of time and
4578 So the central module defines a function that contains initialization code and
4579 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4580 this module is added to an executable by the linker, the initialization
4581 function will be placed into the table of constructors by the linker. The C
4582 startup code will call all constructors before <tt/main/ and all destructors
4583 after <tt/main/, so without any further work, the heap initialization code is
4584 called once the module is linked in.
4586 While it would be possible to add explicit calls to initialization functions
4587 in the startup code, the new approach has several advantages:
4591 If a module is not included, the initialization code is not linked in and not
4592 called. So you don't pay for things you don't need.
4595 Adding another library that needs initialization does not mean that the
4596 startup code has to be changed. Before we had module constructors and
4597 destructors, the startup code for all systems had to be adjusted to call the
4598 new initialization code.
4601 The feature saves memory: Each additional initialization function needs just
4602 two bytes in the table (a pointer to the function).
4607 <sect1>Calling order<p>
4609 The symbols are sorted in increasing priority order by the linker when using
4610 one of the builtin linker configurations, so the functions with lower
4611 priorities come first and are followed by those with higher priorities. The C
4612 library runtime subroutine that walks over the function tables calls the
4613 functions starting from the top of the table - which means that functions with
4614 a high priority are called first.
4616 So when using the C runtime, functions are called with high priority functions
4617 first, followed by low priority functions.
4622 When using these special symbols, please take care of the following:
4627 The linker will only generate function tables, it will not generate code to
4628 call these functions. If you're using the feature in some other than the
4629 existing C environments, you have to write code to call all functions in a
4630 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4631 in the C runtime for an example on how to do this.
4634 The linker will only add addresses of functions that are in modules linked to
4635 the executable. This means that you have to be careful where to place the
4636 condes functions. If initialization or an irq handler is needed for a group of
4637 functions, be sure to place the function into a module that is linked in
4638 regardless of which function is called by the user.
4641 The linker will generate the tables only when requested to do so by the
4642 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4643 be requested separately.
4646 Constructors and destructors may have priorities. These priorities determine
4647 the order of the functions in the table. If your initialization or cleanup code
4648 does depend on other initialization or cleanup code, you have to choose the
4649 priority for the functions accordingly.
4652 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4653 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4654 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4655 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4656 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4657 (interruptor). The linker generates a separate table for each type on request.
4662 <sect>Porting sources from other assemblers<p>
4664 Sometimes it is necessary to port code written for older assemblers to ca65.
4665 In some cases, this can be done without any changes to the source code by
4666 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4667 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4670 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4671 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4672 done by the linker. Most other assemblers generate absolute code, placement is
4673 done within the assembler and there is no external linker.
4675 In general it is not a good idea to write new code using the emulation
4676 features of the assembler, but there may be situations where even this rule is
4681 You need to use some of the ca65 emulation features to simulate the behaviour
4682 of such simple assemblers.
4685 <item>Prepare your sourcecode like this:
4688 ; if you want TASS style labels without colons
4689 .feature labels_without_colons
4691 ; if you want TASS style character constants
4692 ; ("a" instead of the default 'a')
4693 .feature loose_char_term
4695 .word *+2 ; the cbm load address
4700 notice that the two emulation features are mostly useful for porting
4701 sources originally written in/for TASS, they are not needed for the
4702 actual "simple assembler operation" and are not recommended if you are
4703 writing new code from scratch.
4705 <item>Replace all program counter assignments (which are not possible in ca65
4706 by default, and the respective emulation feature works different from what
4707 you'd expect) by another way to skip to memory locations, for example the
4708 <tt><ref id=".RES" name=".RES"></tt> directive.
4712 .res $2000-* ; reserve memory up to $2000
4715 Please note that other than the original TASS, ca65 can never move the program
4716 counter backwards - think of it as if you are assembling to disk with TASS.
4718 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4719 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4720 of <tt/.goto/, everything involving loops must be replaced by
4721 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4723 <item>To assemble code to a different address than it is executed at, use the
4724 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4725 <tt/.offs/-constructs.
4732 .reloc ; back to normal
4735 <item>Then assemble like this:
4738 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4741 Note that you need to use the actual start address minus two, since two bytes
4742 are used for the cbm load address.
4747 <sect>Bugs/Feedback<p>
4749 If you have problems using the assembler, if you find any bugs, or if
4750 you're doing something interesting with the assembler, I would be glad to
4751 hear from you. Feel free to contact me by email
4752 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4758 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4759 Bassewitz. For usage of the binaries and/or sources the following
4760 conditions do apply:
4762 This software is provided 'as-is', without any expressed or implied
4763 warranty. In no event will the authors be held liable for any damages
4764 arising from the use of this software.
4766 Permission is granted to anyone to use this software for any purpose,
4767 including commercial applications, and to alter it and redistribute it
4768 freely, subject to the following restrictions:
4771 <item> The origin of this software must not be misrepresented; you must not
4772 claim that you wrote the original software. If you use this software
4773 in a product, an acknowledgment in the product documentation would be
4774 appreciated but is not required.
4775 <item> Altered source versions must be plainly marked as such, and must not
4776 be misrepresented as being the original software.
4777 <item> This notice may not be removed or altered from any source