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 in the range 1..255. The first one is the index of the source
2134 character, the second one is the mapping. The mapping applies to all
2135 character and string constants when they generate output, and overrides
2136 a 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!
2724 It is also possible to specify features on the command line using the
2725 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2726 This is useful when translating sources written for older assemblers, when
2727 you don't want to change the source code.
2729 As an example, to translate sources written for Andre Fachats xa65
2730 assembler, the features
2733 labels_without_colons, pc_assignment, loose_char_term
2736 may be helpful. They do not make ca65 completely compatible, so you may not
2737 be able to translate the sources without changes, even when enabling these
2738 features. However, I have found several sources that translate without
2739 problems when enabling these features on the command line.
2742 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2744 Insert an option string into the object file. There are two forms of
2745 this command, one specifies the option by a keyword, the second
2746 specifies it as a number. Since usage of the second one needs knowledge
2747 of the internal encoding, its use is not recommended and I will only
2748 describe the first form here.
2750 The command is followed by one of the keywords
2758 a comma and a string. The option is written into the object file
2759 together with the string value. This is currently unidirectional and
2760 there is no way to actually use these options once they are in the
2766 .fileopt comment, "Code stolen from my brother"
2767 .fileopt compiler, "BASIC 2.0"
2768 .fopt author, "J. R. User"
2772 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2774 Import an absolute symbol from another module. The command is followed by a
2775 comma separated list of symbols to import. The command is similar to <tt>
2776 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2777 written to the generated object file, even if the symbol is never referenced
2778 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2779 references for unused symbols).
2784 .forceimport needthisone, needthistoo
2787 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2790 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2792 Declare symbols as global. Must be followed by a comma separated list of
2793 symbols to declare. Symbols from the list, that are defined somewhere in the
2794 source, are exported, all others are imported. Additional <tt><ref
2795 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2796 name=".EXPORT"></tt> commands for the same symbol are allowed.
2805 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2807 Declare symbols as global. Must be followed by a comma separated list of
2808 symbols to declare. Symbols from the list, that are defined somewhere in the
2809 source, are exported, all others are imported. Additional <tt><ref
2810 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2811 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2812 in the list are explicitly marked as zero page symbols.
2820 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2822 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2823 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2824 the operator '>' prepended to each expression in its list.
2829 .lobytes $1234, $2345, $3456, $4567
2830 .hibytes $fedc, $edcb, $dcba, $cba9
2833 which is equivalent to
2836 .byte $34, $45, $56, $67
2837 .byte $fe, $ed, $dc, $cb
2843 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2845 TableLookupLo: .lobytes MyTable
2846 TableLookupHi: .hibytes MyTable
2849 which is equivalent to
2852 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2853 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2856 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2857 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2858 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2861 <sect1><tt>.I16</tt><label id=".I16"><p>
2863 Valid only in 65816 mode. Switch the index registers to 16 bit.
2865 Note: This command will not emit any code, it will tell the assembler to
2866 create 16 bit operands for immediate operands.
2868 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2869 name=".SMART"></tt> commands.
2872 <sect1><tt>.I8</tt><label id=".I8"><p>
2874 Valid only in 65816 mode. Switch the index registers to 8 bit.
2876 Note: This command will not emit any code, it will tell the assembler to
2877 create 8 bit operands for immediate operands.
2879 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2880 name=".SMART"></tt> commands.
2883 <sect1><tt>.IF</tt><label id=".IF"><p>
2885 Conditional assembly: Evaluate an expression and switch assembler output
2886 on or off depending on the expression. The expression must be a constant
2887 expression, that is, all operands must be defined.
2889 A expression value of zero evaluates to FALSE, any other value evaluates
2893 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2895 Conditional assembly: Check if there are any remaining tokens in this line,
2896 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2897 condition is not true, further lines are not assembled until an <tt><ref
2898 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2899 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2901 This command is often used to check if a macro parameter was given. Since an
2902 empty macro parameter will evaluate to nothing, the condition will evaluate
2903 to TRUE if an empty parameter was given.
2917 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2920 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2922 Conditional assembly: Evaluate an expression and switch assembler output
2923 on or off depending on the constness of the expression.
2925 A const expression evaluates to to TRUE, a non const expression (one
2926 containing an imported or currently undefined symbol) evaluates to
2929 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2932 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2934 Conditional assembly: Check if a symbol is defined. Must be followed by
2935 a symbol name. The condition is true if the the given symbol is already
2936 defined, and false otherwise.
2938 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2941 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2943 Conditional assembly: Check if there are any remaining tokens in this line,
2944 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2945 condition is not true, further lines are not assembled until an <tt><ref
2946 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2947 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2949 This command is often used to check if a macro parameter was given.
2950 Since an empty macro parameter will evaluate to nothing, the condition
2951 will evaluate to FALSE if an empty parameter was given.
2964 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2967 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2969 Conditional assembly: Check if a symbol is defined. Must be followed by
2970 a symbol name. The condition is true if the the given symbol is not
2971 defined, and false otherwise.
2973 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2976 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2978 Conditional assembly: Check if a symbol is referenced. Must be followed
2979 by a symbol name. The condition is true if if the the given symbol was
2980 not referenced before, and false otherwise.
2982 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2985 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2987 Conditional assembly: Check if the assembler is currently in 6502 mode
2988 (see <tt><ref id=".P02" name=".P02"></tt> command).
2991 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2993 Conditional assembly: Check if the assembler is currently in 65816 mode
2994 (see <tt><ref id=".P816" name=".P816"></tt> command).
2997 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2999 Conditional assembly: Check if the assembler is currently in 65C02 mode
3000 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3003 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3005 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3006 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3009 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3011 Conditional assembly: Check if a symbol is referenced. Must be followed
3012 by a symbol name. The condition is true if if the the given symbol was
3013 referenced before, and false otherwise.
3015 This command may be used to build subroutine libraries in include files
3016 (you may use separate object modules for this purpose too).
3021 .ifref ToHex ; If someone used this subroutine
3022 ToHex: tay ; Define subroutine
3028 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3031 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3033 Import a symbol from another module. The command is followed by a comma
3034 separated list of symbols to import, with each one optionally followed by
3035 an address specification.
3041 .import bar: zeropage
3044 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3047 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3049 Import a symbol from another module. The command is followed by a comma
3050 separated list of symbols to import. The symbols are explicitly imported
3051 as zero page symbols (that is, symbols with values in byte range).
3059 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3062 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3064 Include a file as binary data. The command expects a string argument
3065 that is the name of a file to include literally in the current segment.
3066 In addition to that, a start offset and a size value may be specified,
3067 separated by commas. If no size is specified, all of the file from the
3068 start offset to end-of-file is used. If no start position is specified
3069 either, zero is assumed (which means that the whole file is inserted).
3074 ; Include whole file
3075 .incbin "sprites.dat"
3077 ; Include file starting at offset 256
3078 .incbin "music.dat", $100
3080 ; Read 100 bytes starting at offset 200
3081 .incbin "graphics.dat", 200, 100
3085 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3087 Include another file. Include files may be nested up to a depth of 16.
3096 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3098 Export a symbol and mark it as an interruptor. This may be used together
3099 with the linker to build a table of interruptor subroutines that are called
3102 Note: The linker has a feature to build a table of marked routines, but it
3103 is your code that must call these routines, so just declaring a symbol as
3104 interruptor does nothing by itself.
3106 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3107 need to use an additional <tt/.export/ statement, this is implied by
3108 <tt/.interruptor/. It may have an optional priority that is separated by a
3109 comma. Higher numeric values mean a higher priority. If no priority is
3110 given, the default priority of 7 is used. Be careful when assigning
3111 priorities to your own module constructors so they won't interfere with the
3112 ones in the cc65 library.
3117 .interruptor IrqHandler
3118 .interruptor Handler, 16
3121 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3122 section <ref id="condes" name="Module constructors/destructors"> explaining
3123 the feature in more detail.
3126 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3128 Switch on or off line continuations using the backslash character
3129 before a newline. The option is off by default.
3130 Note: Line continuations do not work in a comment. A backslash at the
3131 end of a comment is treated as part of the comment and does not trigger
3133 The command must be followed by a '+' or '-' character to switch the
3134 option on or off respectively.
3139 .linecont + ; Allow line continuations
3142 #$20 ; This is legal now
3146 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3148 Enable output to the listing. The command must be followed by a boolean
3149 switch ("on", "off", "+" or "-") and will enable or disable listing
3151 The option has no effect if the listing is not enabled by the command line
3152 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3153 to the listing file, if the counter is greater than zero, and suppressed if
3154 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3160 .list on ; Enable listing output
3164 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3166 Set, how many bytes are shown in the listing for one source line. The
3167 default is 12, so the listing will show only the first 12 bytes for any
3168 source line that generates more than 12 bytes of code or data.
3169 The directive needs an argument, which is either "unlimited", or an
3170 integer constant in the range 4..255.
3175 .listbytes unlimited ; List all bytes
3176 .listbytes 12 ; List the first 12 bytes
3177 .incbin "data.bin" ; Include large binary file
3181 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3183 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3184 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3185 the operator '<' prepended to each expression in its list.
3190 .lobytes $1234, $2345, $3456, $4567
3191 .hibytes $fedc, $edcb, $dcba, $cba9
3194 which is equivalent to
3197 .byte $34, $45, $56, $67
3198 .byte $fe, $ed, $dc, $cb
3204 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3206 TableLookupLo: .lobytes MyTable
3207 TableLookupHi: .hibytes MyTable
3210 which is equivalent to
3213 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3214 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3217 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3218 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3219 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3222 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3224 This command may only be used inside a macro definition. It declares a
3225 list of identifiers as local to the macro expansion.
3227 A problem when using macros are labels: Since they don't change their name,
3228 you get a "duplicate symbol" error if the macro is expanded the second time.
3229 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3230 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3233 Some other assemblers start a new lexical block inside a macro expansion.
3234 This has some drawbacks however, since that will not allow <em/any/ symbol
3235 to be visible outside a macro, a feature that is sometimes useful. The
3236 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3237 to address the problem.
3239 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3243 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3245 Defines the character that start "cheap" local labels. You may use one
3246 of '@' and '?' as start character. The default is '@'.
3248 Cheap local labels are labels that are visible only between two non
3249 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3250 using explicit lexical nesting.
3257 Clear: lda #$00 ; Global label
3258 ?Loop: sta Mem,y ; Local label
3262 Sub: ... ; New global label
3263 bne ?Loop ; ERROR: Unknown identifier!
3267 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3269 Insert a predefined macro package. The command is followed by an
3270 identifier specifying the macro package to insert. Available macro
3274 atari Defines the scrcode macro.
3275 cbm Defines the scrcode macro.
3276 cpu Defines constants for the .CPU variable.
3277 generic Defines generic macros like add and sub.
3278 longbranch Defines conditional long jump macros.
3281 Including a macro package twice, or including a macro package that
3282 redefines already existing macros will lead to an error.
3287 .macpack longbranch ; Include macro package
3289 cmp #$20 ; Set condition codes
3290 jne Label ; Jump long on condition
3293 Macro packages are explained in more detail in section <ref
3294 id="macropackages" name="Macro packages">.
3297 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3299 Start a classic macro definition. The command is followed by an identifier
3300 (the macro name) and optionally by a comma separated list of identifiers
3301 that are macro parameters. A macro definition is terminated by <tt><ref
3302 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3307 .macro ldax arg ; Define macro ldax
3312 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3313 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3314 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3316 See also section <ref id="macros" name="Macros">.
3319 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3321 Start a section of absolute code. The command is followed by a constant
3322 expression that gives the new PC counter location for which the code is
3323 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3326 By default, absolute/relocatable mode is global (valid even when switching
3327 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3328 it can be made segment local.
3330 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3331 code at a specific address is the job of the linker, not the assembler, so
3332 there is usually no reason to assemble code to a specific address.
3337 .org $7FF ; Emit code starting at $7FF
3341 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3343 Output a string to the console without producing an error. This command
3344 is similar to <tt/.ERROR/, however, it does not force an assembler error
3345 that prevents the creation of an object file.
3350 .out "This code was written by the codebuster(tm)"
3353 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3354 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3355 <tt><ref id=".WARNING" name=".WARNING"></tt>
3358 <sect1><tt>.P02</tt><label id=".P02"><p>
3360 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3361 instructions. This is the default if not overridden by the
3362 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3364 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3365 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3368 <sect1><tt>.P816</tt><label id=".P816"><p>
3370 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3371 6502 instruction sets.
3373 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3374 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3377 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3379 Set the page length for the listing. Must be followed by an integer
3380 constant. The value may be "unlimited", or in the range 32 to 127. The
3381 statement has no effect if no listing is generated. The default value is -1
3382 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3383 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3384 after assembly is complete, you cannot use multiple line lengths with one
3385 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3390 .pagelength 66 ; Use 66 lines per listing page
3392 .pagelength unlimited ; Unlimited page length
3396 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3398 Enable the 65C02 instructions set. This instruction set includes all
3399 6502 and 65SC02 instructions.
3401 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3402 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3405 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3407 Pop the last CPU setting from the stack, and activate it.
3409 This command will switch back to the CPU that was last pushed onto the CPU
3410 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3411 remove this entry from the stack.
3413 The assembler will print an error message if the CPU stack is empty when
3414 this command is issued.
3416 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3417 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3420 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3422 Pop the last pushed segment from the stack, and set it.
3424 This command will switch back to the segment that was last pushed onto the
3425 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3426 command, and remove this entry from the stack.
3428 The assembler will print an error message if the segment stack is empty
3429 when this command is issued.
3431 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3434 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3436 Start a nested lexical level with the given name and adds a symbol with this
3437 name to the enclosing scope. All new symbols from now on are in the local
3438 lexical level and are accessible from outside only via <ref id="scopesyntax"
3439 name="explicit scope specification">. Symbols defined outside this local
3440 level may be accessed as long as their names are not used for new symbols
3441 inside the level. Symbols names in other lexical levels do not clash, so you
3442 may use the same names for identifiers. The lexical level ends when the
3443 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3444 may be nested up to a depth of 16 (this is an artificial limit to protect
3445 against errors in the source).
3447 Note: Macro names are always in the global level and in a separate name
3448 space. There is no special reason for this, it's just that I've never
3449 had any need for local macro definitions.
3454 .proc Clear ; Define Clear subroutine, start new level
3456 L1: sta Mem,y ; L1 is local and does not cause a
3457 ; duplicate symbol error if used in other
3460 bne L1 ; Reference local symbol
3462 .endproc ; Leave lexical level
3465 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3469 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3471 Enable the 65SC02 instructions set. This instruction set includes all
3474 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3475 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3478 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3480 Push the currently active CPU onto a stack. The stack has a size of 8
3483 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3484 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3485 later, without knowledge of the current CPU setting.
3487 The assembler will print an error message if the CPU stack is already full,
3488 when this command is issued.
3490 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3491 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3494 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3496 Push the currently active segment onto a stack. The entries on the stack
3497 include the name of the segment and the segment type. The stack has a size
3500 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3501 to switch to another segment and to restore the old segment later, without
3502 even knowing the name and type of the current segment.
3504 The assembler will print an error message if the segment stack is already
3505 full, when this command is issued.
3507 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3510 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3512 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3513 name=".ORG"></tt> command.
3516 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3518 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3519 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3520 a constant expression that tells how many times the commands in the body
3521 should get repeated. Optionally, a comma and an identifier may be specified.
3522 If this identifier is found in the body of the repeat statement, it is
3523 replaced by the current repeat count (starting with zero for the first time
3524 the body is repeated).
3526 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3527 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3528 level will be used, not the one from the outer level.
3532 The following macro will emit a string that is "encrypted" in that all
3533 characters of the string are XORed by the value $55.
3537 .repeat .strlen(Arg), I
3538 .byte .strat(Arg, I) ^ $55
3543 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3546 <sect1><tt>.RES</tt><label id=".RES"><p>
3548 Reserve storage. The command is followed by one or two constant
3549 expressions. The first one is mandatory and defines, how many bytes of
3550 storage should be defined. The second, optional expression must by a
3551 constant byte value that will be used as value of the data. If there
3552 is no fill value given, the linker will use the value defined in the
3553 linker configuration file (default: zero).
3558 ; Reserve 12 bytes of memory with value $AA
3563 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3565 Switch to the RODATA segment. The name of the RODATA segment is always
3566 "RODATA", so this is a shortcut for
3572 The RODATA segment is a segment that is used by the compiler for
3573 readonly data like string constants.
3575 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3578 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3580 Start a nested lexical level with the given name. All new symbols from now
3581 on are in the local lexical level and are accessible from outside only via
3582 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3583 outside this local level may be accessed as long as their names are not used
3584 for new symbols inside the level. Symbols names in other lexical levels do
3585 not clash, so you may use the same names for identifiers. The lexical level
3586 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3587 read. Lexical levels may be nested up to a depth of 16 (this is an
3588 artificial limit to protect against errors in the source).
3590 Note: Macro names are always in the global level and in a separate name
3591 space. There is no special reason for this, it's just that I've never
3592 had any need for local macro definitions.
3597 .scope Error ; Start new scope named Error
3599 File = 1 ; File error
3600 Parse = 2 ; Parse error
3601 .endscope ; Close lexical level
3604 lda #Error::File ; Use symbol from scope Error
3607 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3611 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3613 Switch to another segment. Code and data is always emitted into a
3614 segment, that is, a named section of data. The default segment is
3615 "CODE". There may be up to 254 different segments per object file
3616 (and up to 65534 per executable). There are shortcut commands for
3617 the most common segments ("CODE", "DATA" and "BSS").
3619 The command is followed by a string containing the segment name (there are
3620 some constraints for the name - as a rule of thumb use only those segment
3621 names that would also be valid identifiers). There may also be an optional
3622 address size separated by a colon. See the section covering <tt/<ref
3623 id="address-sizes" name="address sizes">/ for more information.
3625 The default address size for a segment depends on the memory model specified
3626 on the command line. The default is "absolute", which means that you don't
3627 have to use an address size modifier in most cases.
3629 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3630 That is, the segment will reside somewhere in core memory outside the zero
3631 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3632 page and direct (short) addressing is possible for data in this segment.
3634 Beware: Only labels in a segment with the zeropage attribute are marked
3635 as reachable by short addressing. The `*' (PC counter) operator will
3636 work as in other segments and will create absolute variable values.
3638 Please note that a segment cannot have two different address sizes. A
3639 segment specified as zeropage cannot be declared as being absolute later.
3644 .segment "ROM2" ; Switch to ROM2 segment
3645 .segment "ZP2": zeropage ; New direct segment
3646 .segment "ZP2" ; Ok, will use last attribute
3647 .segment "ZP2": absolute ; Error, redecl mismatch
3650 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3651 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3652 id=".RODATA" name=".RODATA"></tt>
3655 <sect1><tt>.SET</tt><label id=".SET"><p>
3657 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3658 name="Numeric variables"> for a full description.
3661 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3663 Switch the CPU instruction set. The command is followed by a string that
3664 specifies the CPU. Possible values are those that can also be supplied to
3665 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3666 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3667 note that support for the sunplus CPU is not available in the freeware
3668 version, because the instruction set of the sunplus CPU is "proprietary
3671 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3672 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3673 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3674 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3675 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3676 <tt><ref id=".P02" name=".P02"></tt>,
3677 <tt><ref id=".P816" name=".P816"></tt>,
3678 <tt><ref id=".PC02" name=".PC02"></tt>,
3679 <tt><ref id=".PSC02" name=".PSC02"></tt>
3682 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3684 Switch on or off smart mode. The command must be followed by a '+' or '-'
3685 character to switch the option on or off respectively. The default is off
3686 (that is, the assembler doesn't try to be smart), but this default may be
3687 changed by the -s switch on the command line.
3689 In smart mode the assembler will do the following:
3692 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3693 and update the operand sizes accordingly. If the operand of such an
3694 instruction cannot be evaluated by the assembler (for example, because
3695 the operand is an imported symbol), a warning is issued. Beware: Since
3696 the assembler cannot trace the execution flow this may lead to false
3697 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3698 instructions to tell the assembler about the current settings.
3699 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3700 used within a procedure declared as <tt/far/, or if the procedure has
3701 no explicit address specification, but it is <tt/far/ because of the
3709 .smart - ; Stop being smart
3712 See: <tt><ref id=".A16" name=".A16"></tt>,
3713 <tt><ref id=".A8" name=".A8"></tt>,
3714 <tt><ref id=".I16" name=".I16"></tt>,
3715 <tt><ref id=".I8" name=".I8"></tt>
3718 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3720 Starts a struct definition. Structs are covered in a separate section named
3721 <ref id="structs" name=""Structs and unions"">.
3723 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3724 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3725 <tt><ref id=".UNION" name=".UNION"></tt>
3728 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3730 Enable the SunPlus instructions set. This command will not work in the
3731 freeware version of the assembler, because the instruction set is
3732 "proprietary and confidential".
3734 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3735 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3736 <tt><ref id=".P816" name=".P816"></tt>
3739 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3741 Allocate space for a struct or union.
3752 .tag Point ; Allocate 4 bytes
3756 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3758 Delete a define style macro definition. The command is followed by an
3759 identifier which specifies the name of the macro to delete. Macro
3760 replacement is switched of when reading the token following the command
3761 (otherwise the macro name would be replaced by its replacement list).
3763 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3764 section <ref id="macros" name="Macros">.
3767 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3769 Starts a union definition. Unions are covered in a separate section named
3770 <ref id="structs" name=""Structs and unions"">.
3772 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3773 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3774 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3777 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3779 Force an assembly warning. The assembler will output a warning message
3780 preceded by "User warning". This warning will always be output, even if
3781 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3782 command line option.
3784 This command may be used to output possible problems when assembling
3793 .warning "Forward jump in jne, cannot optimize!"
3803 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3804 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3805 <tt><ref id=".OUT" name=".OUT"></tt>
3808 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3810 Define word sized data. Must be followed by a sequence of (word ranged,
3811 but not necessarily constant) expressions.
3816 .word $0D00, $AF13, _Clear
3820 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3822 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3823 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3827 .segment "ZEROPAGE", zeropage
3830 Because of the "zeropage" attribute, labels declared in this segment are
3831 addressed using direct addressing mode if possible. You <em/must/ instruct
3832 the linker to place this segment somewhere in the address range 0..$FF
3833 otherwise you will get errors.
3835 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3839 <sect>Macros<label id="macros"><p>
3842 <sect1>Introduction<p>
3844 Macros may be thought of as "parametrized super instructions". Macros are
3845 sequences of tokens that have a name. If that name is used in the source
3846 file, the macro is "expanded", that is, it is replaced by the tokens that
3847 were specified when the macro was defined.
3850 <sect1>Macros without parameters<p>
3852 In its simplest form, a macro does not have parameters. Here's an
3856 .macro asr ; Arithmetic shift right
3857 cmp #$80 ; Put bit 7 into carry
3858 ror ; Rotate right with carry
3862 The macro above consists of two real instructions, that are inserted into
3863 the code, whenever the macro is expanded. Macro expansion is simply done
3864 by using the name, like this:
3873 <sect1>Parametrized macros<p>
3875 When using macro parameters, macros can be even more useful:
3889 When calling the macro, you may give a parameter, and each occurrence of
3890 the name "addr" in the macro definition will be replaced by the given
3909 A macro may have more than one parameter, in this case, the parameters
3910 are separated by commas. You are free to give less parameters than the
3911 macro actually takes in the definition. You may also leave intermediate
3912 parameters empty. Empty parameters are replaced by empty space (that is,
3913 they are removed when the macro is expanded). If you have a look at our
3914 macro definition above, you will see, that replacing the "addr" parameter
3915 by nothing will lead to wrong code in most lines. To help you, writing
3916 macros with a variable parameter list, there are some control commands:
3918 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3919 returns true, if there are any tokens on the remainder of the line. Since
3920 empty parameters are replaced by nothing, this may be used to test if a given
3921 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3924 Look at this example:
3927 .macro ldaxy a, x, y
3940 This macro may be called as follows:
3943 ldaxy 1, 2, 3 ; Load all three registers
3945 ldaxy 1, , 3 ; Load only a and y
3947 ldaxy , , 3 ; Load y only
3950 There's another helper command for determining, which macro parameters are
3951 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3952 replaced by the parameter count given, <em/including/ intermediate empty macro
3956 ldaxy 1 ; .PARAMCOUNT = 1
3957 ldaxy 1,,3 ; .PARAMCOUNT = 3
3958 ldaxy 1,2 ; .PARAMCOUNT = 2
3959 ldaxy 1, ; .PARAMCOUNT = 2
3960 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3963 Macro parameters may optionally be enclosed into curly braces. This allows the
3964 inclusion of tokens that would otherwise terminate the parameter (the comma in
3965 case of a macro parameter).
3968 .macro foo arg1, arg2
3972 foo ($00,x) ; Two parameters passed
3973 foo {($00,x)} ; One parameter passed
3976 In the first case, the macro is called with two parameters: '<tt/($00/'
3977 and 'x)'. The comma is not passed to the macro, since it is part of the
3978 calling sequence, not the parameters.
3980 In the second case, '($00,x)' is passed to the macro, this time
3981 including the comma.
3984 <sect1>Detecting parameter types<p>
3986 Sometimes it is nice to write a macro that acts differently depending on the
3987 type of the argument supplied. An example would be a macro that loads a 16 bit
3988 value from either an immediate operand, or from memory. The <tt/<ref
3989 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3990 functions will allow you to do exactly this:
3994 .if (.match (.left (1, {arg}), #))
3996 lda #<(.right (.tcount ({arg})-1, {arg}))
3997 ldx #>(.right (.tcount ({arg})-1, {arg}))
3999 ; assume absolute or zero page
4006 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4007 check if its argument begins with a hash mark. If so, two immediate loads are
4008 emitted, Otherwise a load from an absolute zero page memory location is
4009 assumed. Please note how the curly braces are used to enclose parameters to
4010 pseudo functions handling token lists. This is necessary, because the token
4011 lists may include commas or parens, which would be treated by the assembler
4014 The macro can be used as
4019 ldax #$1234 ; X=$12, A=$34
4021 ldax foo ; X=$56, A=$78
4025 <sect1>Recursive macros<p>
4027 Macros may be used recursively:
4030 .macro push r1, r2, r3
4039 There's also a special macro to help writing recursive macros: <tt><ref
4040 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
4044 .macro push r1, r2, r3, r4, r5, r6, r7
4046 ; First parameter is empty
4052 push r2, r3, r4, r5, r6, r7
4056 When expanding this macro, the expansion will push all given parameters
4057 until an empty one is encountered. The macro may be called like this:
4060 push $20, $21, $32 ; Push 3 ZP locations
4061 push $21 ; Push one ZP location
4065 <sect1>Local symbols inside macros<p>
4067 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4068 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4069 Have a look at the inc16 macro above. Here is it again:
4083 If you have a closer look at the code, you will notice, that it could be
4084 written more efficiently, like this:
4095 But imagine what happens, if you use this macro twice? Since the label "Skip"
4096 has the same name both times, you get a "duplicate symbol" error. Without a
4097 way to circumvent this problem, macros are not as useful, as they could be.
4098 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4099 It declares one or more symbols as local to the macro expansion. The names of
4100 local variables are replaced by a unique name in each separate macro
4101 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4105 .local Skip ; Make Skip a local symbol
4109 Skip: ; Not visible outside
4113 Another solution is of course to start a new lexical block inside the macro
4114 that hides any labels:
4128 <sect1>C style macros<p>
4130 Starting with version 2.5 of the assembler, there is a second macro type
4131 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4132 similar to the classic macro type described above, but behaviour is sometimes
4137 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4138 span more than a line. You may use line continuation (see <tt><ref
4139 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4140 more than one line for increased readability, but the macro itself
4141 may not contain an end-of-line token.
4143 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4144 the name space with classic macros, but they are detected and replaced
4145 at the scanner level. While classic macros may be used in every place,
4146 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4147 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4148 they are more versatile in some situations.
4150 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4151 parameters. While classic macros may have empty parameters, this is
4152 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4153 For this macro type, the number of actual parameters must match
4154 exactly the number of formal parameters.
4156 To make this possible, formal parameters are enclosed in braces when
4157 defining the macro. If there are no parameters, the empty braces may
4160 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4161 contain end-of-line tokens, there are things that cannot be done. They
4162 may not contain several processor instructions for example. So, while
4163 some things may be done with both macro types, each type has special
4164 usages. The types complement each other.
4168 Let's look at a few examples to make the advantages and disadvantages
4171 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4172 following <tt/.DEFINE/:
4177 foo EQU $1234 ; This is accepted now
4180 You may use the directive to define string constants used elsewhere:
4183 ; Define the version number
4184 .define VERSION "12.3a"
4190 Macros with parameters may also be useful:
4193 .define DEBUG(message) .out message
4195 DEBUG "Assembling include file #3"
4198 Note that, while formal parameters have to be placed in braces, this is
4199 not true for the actual parameters. Beware: Since the assembler cannot
4200 detect the end of one parameter, only the first token is used. If you
4201 don't like that, use classic macros instead:
4204 .macro DEBUG message
4209 (This is an example where a problem can be solved with both macro types).
4212 <sect1>Characters in macros<p>
4214 When using the <ref id="option-t" name="-t"> option, characters are translated
4215 into the target character set of the specific machine. However, this happens
4216 as late as possible. This means that strings are translated if they are part
4217 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4218 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4219 used as part of an expression.
4221 This behaviour is very intuitive outside of macros but may be confusing when
4222 doing more complex macros. If you compare characters against numeric values,
4223 be sure to take the translation into account.
4226 <sect1>Deleting macros<p>
4228 Macros can be deleted. This will not work if the macro that should be deleted
4229 is currently expanded as in the following non working example:
4233 .delmacro notworking
4236 notworking ; Will not work
4239 The commands to delete classic and define style macros differ. Classic macros
4240 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4241 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4242 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4250 .byte value ; Emit one byte with value 1
4251 mac ; Emit another byte with value 2
4256 .byte value ; Error: Unknown identifier
4257 mac ; Error: Missing ":"
4260 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4261 the name of such a macro is replaced by its replacement list on a very low
4262 level. To get the actual name, macro replacement has to be switched off when
4263 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4264 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4265 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4266 different commands increases flexibility.
4269 <sect>Macro packages<label id="macropackages"><p>
4271 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4272 macro packages may be included with just one command. Available macro packages
4276 <sect1><tt>.MACPACK generic</tt><p>
4278 This macro package defines macros that are useful in almost any program.
4279 Currently defined macros are:
4314 <sect1><tt>.MACPACK longbranch</tt><p>
4316 This macro package defines long conditional jumps. They are named like the
4317 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4318 definition for the "<tt/jeq/" macro, the other macros are built using the same
4323 .if .def(Target) .and ((*+2)-(Target) <= 127)
4332 All macros expand to a short branch, if the label is already defined (back
4333 jump) and is reachable with a short jump. Otherwise the macro expands to a
4334 conditional branch with the branch condition inverted, followed by an absolute
4335 jump to the actual branch target.
4337 The package defines the following macros:
4340 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4345 <sect1><tt>.MACPACK atari</tt><p>
4347 The atari macro package will define a macro named <tt/scrcode/. It takes a
4348 string as argument and places this string into memory translated into screen
4352 <sect1><tt>.MACPACK cbm</tt><p>
4354 The cbm macro package will define a macro named <tt/scrcode/. It takes a
4355 string as argument and places this string into memory translated into screen
4359 <sect1><tt>.MACPACK cpu</tt><p>
4361 This macro package does not define any macros but constants used to examine
4362 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4363 each supported CPU a constant similar to
4375 is defined. These constants may be used to determine the exact type of the
4376 currently enabled CPU. In addition to that, for each CPU instruction set,
4377 another constant is defined:
4389 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4390 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4391 currently enabled CPU supports a specific instruction set. For example the
4392 65C02 supports all instructions of the 65SC02 CPU, so it has the
4393 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4397 .if (.cpu .bitand CPU_ISET_65SC02)
4405 it is possible to determine if the
4411 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4412 CPUs (the latter two are upwards compatible to the 65SC02).
4416 <sect>Predefined constants<label id="predefined-constants"><p>
4418 For better orthogonality, the assembler defines similar symbols as the
4419 compiler, depending on the target system selected:
4422 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
4423 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4424 <item><tt/__ATARI__/ - Target system is <tt/atari/
4425 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4426 <item><tt/__BBC__/ - Target system is <tt/bbc/
4427 <item><tt/__C128__/ - Target system is <tt/c128/
4428 <item><tt/__C16__/ - Target system is <tt/c16/
4429 <item><tt/__C64__/ - Target system is <tt/c64/
4430 <item><tt/__CBM__/ - Target is a Commodore system
4431 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4432 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4433 <item><tt/__GEOS__/ - Target system is <tt/geos/
4434 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4435 <item><tt/__NES__/ - Target system is <tt/nes/
4436 <item><tt/__PET__/ - Target system is <tt/pet/
4437 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4438 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4439 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4443 <sect>Structs and unions<label id="structs"><p>
4445 <sect1>Structs and unions Overview<p>
4447 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4448 are to some degree comparable to their C counterparts. Both have a list of
4449 members. Each member allocates storage and may optionally have a name, which,
4450 in case of a struct, is the offset from the beginning and, in case of a union,
4454 <sect1>Declaration<p>
4456 Here is an example for a very simple struct with two members and a total size
4466 A union shares the total space between all its members, its size is the same
4467 as that of the largest member. The offset of all members relative to the union
4477 A struct or union must not necessarily have a name. If it is anonymous, no
4478 local scope is opened, the identifiers used to name the members are placed
4479 into the current scope instead.
4481 A struct may contain unnamed members and definitions of local structs. The
4482 storage allocators may contain a multiplier, as in the example below:
4487 .word 2 ; Allocate two words
4494 <sect1>The <tt/.TAG/ keyword<p>
4496 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4497 for an already defined struct or unions within another struct:
4511 Space for a struct or union may be allocated using the <ref id=".TAG"
4512 name=".TAG"> directive.
4518 Currently, members are just offsets from the start of the struct or union. To
4519 access a field of a struct, the member offset has to be added to the address
4520 of the struct itself:
4523 lda C+Circle::Radius ; Load circle radius into A
4526 This may change in a future version of the assembler.
4529 <sect1>Limitations<p>
4531 Structs and unions are currently implemented as nested symbol tables (in fact,
4532 they were a by-product of the improved scoping rules). Currently, the
4533 assembler has no idea of types. This means that the <ref id=".TAG"
4534 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4535 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4536 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4537 this structure accessible by using the '::' operator.
4541 <sect>Module constructors/destructors<label id="condes"><p>
4543 <em>Note:</em> This section applies mostly to C programs, so the explanation
4544 below uses examples from the C libraries. However, the feature may also be
4545 useful for assembler programs.
4548 <sect1>Module constructors/destructors Overview<p>
4550 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4551 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4552 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
4553 special way. The linker is able to generate tables with all functions of a
4554 specific type. Such a table will <em>only</em> include symbols from object
4555 files that are linked into a specific executable. This may be used to add
4556 initialization and cleanup code for library modules, or a table of interrupt
4559 The C heap functions are an example where module initialization code is used.
4560 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4561 variables that contain the start and the end of the heap, pointers to the free
4562 list and so on. Since the end of the heap depends on the size and start of the
4563 stack, it must be initialized at runtime. However, initializing these
4564 variables for programs that do not use the heap are a waste of time and
4567 So the central module defines a function that contains initialization code and
4568 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4569 this module is added to an executable by the linker, the initialization
4570 function will be placed into the table of constructors by the linker. The C
4571 startup code will call all constructors before <tt/main/ and all destructors
4572 after <tt/main/, so without any further work, the heap initialization code is
4573 called once the module is linked in.
4575 While it would be possible to add explicit calls to initialization functions
4576 in the startup code, the new approach has several advantages:
4580 If a module is not included, the initialization code is not linked in and not
4581 called. So you don't pay for things you don't need.
4584 Adding another library that needs initialization does not mean that the
4585 startup code has to be changed. Before we had module constructors and
4586 destructors, the startup code for all systems had to be adjusted to call the
4587 new initialization code.
4590 The feature saves memory: Each additional initialization function needs just
4591 two bytes in the table (a pointer to the function).
4596 <sect1>Calling order<p>
4598 The symbols are sorted in increasing priority order by the linker when using
4599 one of the builtin linker configurations, so the functions with lower
4600 priorities come first and are followed by those with higher priorities. The C
4601 library runtime subroutine that walks over the function tables calls the
4602 functions starting from the top of the table - which means that functions with
4603 a high priority are called first.
4605 So when using the C runtime, functions are called with high priority functions
4606 first, followed by low priority functions.
4611 When using these special symbols, please take care of the following:
4616 The linker will only generate function tables, it will not generate code to
4617 call these functions. If you're using the feature in some other than the
4618 existing C environments, you have to write code to call all functions in a
4619 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4620 in the C runtime for an example on how to do this.
4623 The linker will only add addresses of functions that are in modules linked to
4624 the executable. This means that you have to be careful where to place the
4625 condes functions. If initialization or an irq handler is needed for a group of
4626 functions, be sure to place the function into a module that is linked in
4627 regardless of which function is called by the user.
4630 The linker will generate the tables only when requested to do so by the
4631 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4632 be requested separately.
4635 Constructors and destructors may have priorities. These priorities determine
4636 the order of the functions in the table. If your initialization or cleanup code
4637 does depend on other initialization or cleanup code, you have to choose the
4638 priority for the functions accordingly.
4641 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4642 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4643 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4644 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4645 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4646 (interruptor). The linker generates a separate table for each type on request.
4651 <sect>Porting sources from other assemblers<p>
4653 Sometimes it is necessary to port code written for older assemblers to ca65.
4654 In some cases, this can be done without any changes to the source code by
4655 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4656 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4659 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4660 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4661 done by the linker. Most other assemblers generate absolute code, placement is
4662 done within the assembler and there is no external linker.
4664 In general it is not a good idea to write new code using the emulation
4665 features of the assembler, but there may be situations where even this rule is
4670 You need to use some of the ca65 emulation features to simulate the behaviour
4671 of such simple assemblers.
4674 <item>Prepare your sourcecode like this:
4677 ; if you want TASS style labels without colons
4678 .feature labels_without_colons
4680 ; if you want TASS style character constants
4681 ; ("a" instead of the default 'a')
4682 .feature loose_char_term
4684 .word *+2 ; the cbm load address
4689 notice that the two emulation features are mostly useful for porting
4690 sources originally written in/for TASS, they are not needed for the
4691 actual "simple assembler operation" and are not recommended if you are
4692 writing new code from scratch.
4694 <item>Replace all program counter assignments (which are not possible in ca65
4695 by default, and the respective emulation feature works different from what
4696 you'd expect) by another way to skip to memory locations, for example the
4697 <tt><ref id=".RES" name=".RES"></tt> directive.
4701 .res $2000-* ; reserve memory up to $2000
4704 Please note that other than the original TASS, ca65 can never move the program
4705 counter backwards - think of it as if you are assembling to disk with TASS.
4707 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4708 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4709 of <tt/.goto/, everything involving loops must be replaced by
4710 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4712 <item>To assemble code to a different address than it is executed at, use the
4713 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4714 <tt/.offs/-constructs.
4721 .reloc ; back to normal
4724 <item>Then assemble like this:
4727 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4730 Note that you need to use the actual start address minus two, since two bytes
4731 are used for the cbm load address.
4736 <sect>Bugs/Feedback<p>
4738 If you have problems using the assembler, if you find any bugs, or if
4739 you're doing something interesting with the assembler, I would be glad to
4740 hear from you. Feel free to contact me by email
4741 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4747 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4748 Bassewitz. For usage of the binaries and/or sources the following
4749 conditions do apply:
4751 This software is provided 'as-is', without any expressed or implied
4752 warranty. In no event will the authors be held liable for any damages
4753 arising from the use of this software.
4755 Permission is granted to anyone to use this software for any purpose,
4756 including commercial applications, and to alter it and redistribute it
4757 freely, subject to the following restrictions:
4760 <item> The origin of this software must not be misrepresented; you must not
4761 claim that you wrote the original software. If you use this software
4762 in a product, an acknowledgment in the product documentation would be
4763 appreciated but is not required.
4764 <item> Altered source versions must be plainly marked as such, and must not
4765 be misrepresented as being the original software.
4766 <item> This notice may not be removed or altered from any source