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
95 -g Add debug info to object file
97 -i Ignore case of symbols
98 -l name Create a listing file if assembly was ok
99 -mm model Set the memory model
100 -o name Name the output file
102 -t sys Set the target system
103 -v Increase verbosity
106 --auto-import Mark unresolved symbols as import
107 --bin-include-dir dir Set a search path for binary includes
108 --cpu type Set cpu type
109 --create-dep name Create a make dependency file
110 --create-full-dep name Create a full make dependency file
111 --debug-info Add debug info to object file
112 --feature name Set an emulation feature
113 --forget-inc-paths Forget include search paths
114 --help Help (this text)
115 --ignore-case Ignore case of symbols
116 --include-dir dir Set an include directory search path
117 --large-alignment Don't warn about large alignments
118 --listing name Create a listing file if assembly was ok
119 --list-bytes n Maximum number of bytes per listing line
120 --macpack-dir dir Set a macro package directory
121 --memory-model model Set the memory model
122 --pagelength n Set the page length for the listing
123 --relax-checks Relax some checks (see docs)
124 --smart Enable smart mode
125 --target sys Set the target system
126 --verbose Increase verbosity
127 --version Print the assembler version
128 ---------------------------------------------------------------------------
132 <sect1>Command line options in detail<p>
134 Here is a description of all the command line options:
138 <label id="option--bin-include-dir">
139 <tag><tt>--bin-include-dir dir</tt></tag>
141 Name a directory which is searched for binary include files. The option
142 may be used more than once to specify more than one directory to search. The
143 current directory is always searched first before considering any
144 additional directories. See also the section about <ref id="search-paths"
145 name="search paths">.
148 <label id="option--cpu">
149 <tag><tt>--cpu type</tt></tag>
151 Set the default for the CPU type. The option takes a parameter, which
154 6502, 65SC02, 65C02, 65816, sunplus, sweet16, HuC6280
156 The sunplus cpu is not available in the freeware version, because the
157 instruction set is "proprietary and confidential".
160 <label id="option-create-dep">
161 <tag><tt>--create-dep name</tt></tag>
163 Tells the assembler to generate a file containing the dependency list for
164 the assembled module in makefile syntax. The output is written to a file
165 with the given name. The output does not include files passed via debug
166 information to the assembler.
169 <label id="option-create-full-dep">
170 <tag><tt>--create-full-dep name</tt></tag>
172 Tells the assembler to generate a file containing the dependency list for
173 the assembled module in makefile syntax. The output is written to a file
174 with the given name. The output does include files passed via debug
175 information to the assembler.
178 <label id="option--feature">
179 <tag><tt>--feature name</tt></tag>
181 Enable an emulation feature. This is identical as using <tt/.FEATURE/
182 in the source with two exceptions: Feature names must be lower case, and
183 each feature must be specified by using an extra <tt/--feature/ option,
184 comma separated lists are not allowed.
186 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
187 command for a list of emulation features.
190 <label id="option--forget-inc-paths">
191 <tag><tt>--forget-inc-paths</tt></tag>
193 Forget the builtin include paths. This is most useful when building
194 customized assembler modules, in which case the standard header files should
198 <label id="option-g">
199 <tag><tt>-g, --debug-info</tt></tag>
201 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
202 used, the assembler will add a section to the object file that contains
203 all symbols (including local ones) together with the symbol values and
204 source file positions. The linker will put these additional symbols into
205 the VICE label file, so even local symbols can be seen in the VICE
209 <label id="option-h">
210 <tag><tt>-h, --help</tt></tag>
212 Print the short option summary shown above.
215 <label id="option-i">
216 <tag><tt>-i, --ignore-case</tt></tag>
218 This option makes the assembler case insensitive on identifiers and labels.
219 This option will override the default, but may itself be overridden by the
220 <tt><ref id=".CASE" name=".CASE"></tt> control command.
223 <label id="option-l">
224 <tag><tt>-l name, --listing name</tt></tag>
226 Generate an assembler listing with the given name. A listing file will
227 never be generated in case of assembly errors.
230 <label id="option--large-alignment">
231 <tag><tt>--large-alignment</tt></tag>
233 Disable warnings about a large combined alignment. See the discussion of the
234 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
237 <label id="option--list-bytes">
238 <tag><tt>--list-bytes n</tt></tag>
240 Set the maximum number of bytes printed in the listing for one line of
241 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
242 for more information. The value zero can be used to encode an unlimited
243 number of printed bytes.
246 <label id="option--macpack-dir">
247 <tag><tt>--macpack-dir dir</tt></tag>
249 This options allows to specify a directory containing macro files that are
250 used instead of the builtin images when a <tt><ref id=".MACPACK"
251 name=".MACPACK"></tt> directive is encountered. If <tt>--macpack-dir</tt>
252 was specified, a <tt>.mac</tt> extension is added to the package name and
253 the resulting file is loaded from the given directory. This is most useful
254 when debugging the builtin macro packages.
257 <label id="option-mm">
258 <tag><tt>-mm model, --memory-model model</tt></tag>
260 Define the default memory model. Possible model specifiers are near, far and
264 <label id="option-o">
265 <tag><tt>-o name</tt></tag>
267 The default output name is the name of the input file with the extension
268 replaced by ".o". If you don't like that, you may give another name with
269 the -o option. The output file will be placed in the same directory as
270 the source file, or, if -o is given, the full path in this name is used.
273 <label id="option--pagelength">
274 <tag><tt>--pagelength n</tt></tag>
276 sets the length of a listing page in lines. See the <tt><ref
277 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
280 <label id="option--relax-checks">
281 <tag><tt>--relax-checks</tt></tag>
283 Relax some checks done by the assembler. This will allow code that is an
284 error in most cases and flagged as such by the assembler, but can be valid
285 in special situations.
289 <item>Short branches between two different segments.
290 <item>Byte sized address loads where the address is not a zeropage address.
294 <label id="option-s">
295 <tag><tt>-s, --smart-mode</tt></tag>
297 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
298 pseudo instruction) the assembler will track usage of the <tt/REP/ and
299 <tt/SEP/ instructions in 65816 mode and update the operand sizes
300 accordingly. If the operand of such an instruction cannot be evaluated by
301 the assembler (for example, because the operand is an imported symbol), a
304 Beware: Since the assembler cannot trace the execution flow this may
305 lead to false results in some cases. If in doubt, use the .ixx and .axx
306 instructions to tell the assembler about the current settings. Smart
307 mode is off by default.
310 <label id="option-t">
311 <tag><tt>-t sys, --target sys</tt></tag>
313 Set the target system. This will enable translation of character strings and
314 character constants into the character set of the target platform. The
315 default for the target system is "none", which means that no translation
316 will take place. The assembler supports the same target systems as the
317 compiler, see there for a list.
319 Depending on the target, the default CPU type is also set. This can be
320 overriden by using the <tt/<ref id="option--cpu" name="--cpu">/ option.
323 <label id="option-v">
324 <tag><tt>-v, --verbose</tt></tag>
326 Increase the assembler verbosity. Usually only needed for debugging
327 purposes. You may use this option more than one time for even more
331 <label id="option-D">
332 <tag><tt>-D</tt></tag>
334 This option allows you to define symbols on the command line. Without a
335 value, the symbol is defined with the value zero. When giving a value,
336 you may use the '$' prefix for hexadecimal symbols. Please note
337 that for some operating systems, '$' has a special meaning, so
338 you may have to quote the expression.
341 <label id="option-I">
342 <tag><tt>-I dir, --include-dir dir</tt></tag>
344 Name a directory which is searched for include files. The option may be
345 used more than once to specify more than one directory to search. The
346 current directory is always searched first before considering any
347 additional directories. See also the section about <ref id="search-paths"
348 name="search paths">.
351 <label id="option-U">
352 <tag><tt>-U, --auto-import</tt></tag>
354 Mark symbols that are not defined in the sources as imported symbols. This
355 should be used with care since it delays error messages about typos and such
356 until the linker is run. The compiler uses the equivalent of this switch
357 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
358 symbols for the runtime library. However, the compiler is supposed to
359 generate code that runs through the assembler without problems, something
360 which is not always true for assembler programmers.
363 <label id="option-V">
364 <tag><tt>-V, --version</tt></tag>
366 Print the version number of the assembler. If you send any suggestions
367 or bugfixes, please include the version number.
370 <label id="option-W">
371 <tag><tt>-Wn</tt></tag>
373 Set the warning level for the assembler. Using -W2 the assembler will
374 even warn about such things like unused imported symbols. The default
375 warning level is 1, and it would probably be silly to set it to
383 <sect>Search paths<label id="search-paths"><p>
385 Normal include files are searched in the following places:
388 <item>The current directory.
389 <item>A compiled-in directory, which is often <tt>/usr/lib/cc65/asminc</tt>
391 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
392 <item>A subdirectory named <tt/asminc/ of the directory defined in the
393 environment variable <tt/CC65_HOME/, if it is defined.
394 <item>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
398 Binary include files are searched in the following places:
401 <item>The current directory.
402 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
403 name="--bin-include-dir">/ option on the command line.
408 <sect>Input format<p>
410 <sect1>Assembler syntax<p>
412 The assembler accepts the standard 6502/65816 assembler syntax. One line may
413 contain a label (which is identified by a colon), and, in addition to the
414 label, an assembler mnemonic, a macro, or a control command (see section <ref
415 id="control-commands" name="Control Commands"> for supported control
416 commands). Alternatively, the line may contain a symbol definition using
417 the '=' token. Everything after a semicolon is handled as a comment (that is,
420 Here are some examples for valid input lines:
423 Label: ; A label and a comment
424 lda #$20 ; A 6502 instruction plus comment
425 L1: ldx #$20 ; Same with label
426 L2: .byte "Hello world" ; Label plus control command
427 mymac $20 ; Macro expansion
428 MySym = 3*L1 ; Symbol definition
429 MaSym = Label ; Another symbol
432 The assembler accepts
435 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
436 <tt><ref id=".P02" name=".P02"></tt> command was given).
437 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
438 <ref id="6502X-mode" name="6502X mode">.
439 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
440 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
441 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
442 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
443 <item>all valid 65618 mnemonics when in 65816 mode (after the
444 <tt><ref id=".P816" name=".P816"></tt> command was given).
445 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
446 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
452 In 65816 mode several aliases are accepted in addition to the official
456 BGE is an alias for BCS
457 BLT is an alias for BCC
458 CPA is an alias for CMP
459 DEA is an alias for DEC A
460 INA is an alias for INC A
461 SWA is an alias for XBA
462 TAD is an alias for TCD
463 TAS is an alias for TCS
464 TDA is an alias for TDC
465 TSA is an alias for TSC
470 <sect1>6502X mode<label id="6502X-mode"><p>
472 6502X mode is an extension to the normal 6502 mode. In this mode, several
473 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
474 these instructions are illegal, there are no official mnemonics for them. The
475 unofficial ones are taken from <htmlurl
476 url="http://www.oxyron.de/html/opcodes02.html"
477 name="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
478 ones marked as "stable" are supported. The following table uses information
479 from the mentioned web page, for more information, see there.
482 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
483 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
484 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
485 <item><tt>AXS: X:=A and X-#{imm};</tt>
486 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
487 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
488 <item><tt>LAS: A,X,S:={adr} and S;</tt>
489 <item><tt>LAX: A,X:={adr};</tt>
490 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
491 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
492 <item><tt>SAX: {adr}:=A and X;</tt>
493 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
494 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
499 <sect1>sweet16 mode<label id="sweet16-mode"><p>
501 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
502 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
503 generate code for this pseudo CPU when switched into sweet16 mode. The
504 following is special in sweet16 mode:
508 <item>The '@' character denotes indirect addressing and is no longer available
509 for cheap local labels. If you need cheap local labels, you will have to
510 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
511 name=".LOCALCHAR">/ command.
513 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
514 these identifiers are reserved words.
518 Please note that the assembler does neither supply the interpreter needed for
519 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
520 nor does it call the interpreter. All this must be done by your program. Apple
521 ][ programmers do probably know how to use sweet16 mode.
523 For more information about SWEET 16, see
524 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
525 name="http://www.6502.org/source/interpreters/sweet16.htm">.
528 <sect1>Number format<p>
530 For literal values, the assembler accepts the widely used number formats: A
531 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
532 denotes a binary value, and a bare number is interpreted as a decimal. There
533 are currently no octal values and no floats.
536 <sect1>Conditional assembly<p>
538 Please note that when using the conditional directives (<tt/.IF/ and friends),
539 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
540 that are not assembled. The reason for this behaviour is that the assembler
541 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
542 conversion of the input stream into tokens still takes place. As a consequence
543 conditional assembly directives may <bf/not/ be used to prevent normal text
544 (used as a comment or similar) from being assembled. <p>
550 <sect1>Expression evaluation<p>
552 All expressions are evaluated with (at least) 32 bit precision. An
553 expression may contain constant values and any combination of internal and
554 external symbols. Expressions that cannot be evaluated at assembly time
555 are stored inside the object file for evaluation by the linker.
556 Expressions referencing imported symbols must always be evaluated by the
560 <sect1>Size of an expression result<p>
562 Sometimes, the assembler must know about the size of the value that is the
563 result of an expression. This is usually the case, if a decision has to be
564 made, to generate a zero page or an absolute memory references. In this
565 case, the assembler has to make some assumptions about the result of an
569 <item> If the result of an expression is constant, the actual value is
570 checked to see if it's a byte sized expression or not.
571 <item> If the expression is explicitly casted to a byte sized expression by
572 one of the '>', '<' or '^' operators, it is a byte expression.
573 <item> If this is not the case, and the expression contains a symbol,
574 explicitly declared as zero page symbol (by one of the .importzp or
575 .exportzp instructions), then the whole expression is assumed to be
577 <item> If the expression contains symbols that are not defined, and these
578 symbols are local symbols, the enclosing scopes are searched for a
579 symbol with the same name. If one exists and this symbol is defined,
580 its attributes are used to determine the result size.
581 <item> In all other cases the expression is assumed to be word sized.
584 Note: If the assembler is not able to evaluate the expression at assembly
585 time, the linker will evaluate it and check for range errors as soon as
589 <sect1>Boolean expressions<p>
591 In the context of a boolean expression, any non zero value is evaluated as
592 true, any other value to false. The result of a boolean expression is 1 if
593 it's true, and zero if it's false. There are boolean operators with extreme
594 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
595 operators are shortcut operators. That is, if the result of the expression is
596 already known, after evaluating the left hand side, the right hand side is
600 <sect1>Constant expressions<p>
602 Sometimes an expression must evaluate to a constant without looking at any
603 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
604 that decides if parts of the code are assembled or not. An expression used in
605 the <tt/.IF/ command cannot reference a symbol defined later, because the
606 decision about the <tt/.IF/ must be made at the point when it is read. If the
607 expression used in such a context contains only constant numerical values,
608 there is no problem. When unresolvable symbols are involved it may get harder
609 for the assembler to determine if the expression is actually constant, and it
610 is even possible to create expressions that aren't recognized as constant.
611 Simplifying the expressions will often help.
613 In cases where the result of the expression is not needed immediately, the
614 assembler will delay evaluation until all input is read, at which point all
615 symbols are known. So using arbitrary complex constant expressions is no
616 problem in most cases.
620 <sect1>Available operators<label id="operators"><p>
624 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
625 | Built-in string functions| 0@
627 | Built-in pseudo-variables| 1@
628 | Built-in pseudo-functions| 1@
629 +| Unary positive| 1@
630 -| Unary negative| 1@
632 .BITNOT| Unary bitwise not| 1@
634 .LOBYTE| Unary low-byte operator| 1@
636 .HIBYTE| Unary high-byte operator| 1@
638 .BANKBYTE| Unary bank-byte operator| 1@
640 *| Multiplication| 2@
642 .MOD| Modulo operator| 2@
644 .BITAND| Bitwise and| 2@
646 .BITXOR| Binary bitwise xor| 2@
648 .SHL| Shift-left operator| 2@
650 .SHR| Shift-right operator| 2@
652 +| Binary addition| 3@
653 -| Binary subtraction| 3@
655 .BITOR| Bitwise or| 3@
657 = | Compare operator (equal)| 4@
658 <>| Compare operator (not equal)| 4@
659 <| Compare operator (less)| 4@
660 >| Compare operator (greater)| 4@
661 <=| Compare operator (less or equal)| 4@
662 >=| Compare operator (greater or equal)| 4@
665 .AND| Boolean and| 5@
666 .XOR| Boolean xor| 5@
668 ||<newline>
672 .NOT| Boolean not| 7@<hline>
674 <caption>Available operators, sorted by precedence
677 To force a specific order of evaluation, parentheses may be used, as usual.
681 <sect>Symbols and labels<p>
683 A symbol or label is an identifier that starts with a letter and is followed
684 by letters and digits. Depending on some features enabled (see
685 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
686 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
687 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
688 other characters may be present. Use of identifiers consisting of a single
689 character will not work in all cases, because some of these identifiers are
690 reserved keywords (for example "A" is not a valid identifier for a label,
691 because it is the keyword for the accumulator).
693 The assembler allows you to use symbols instead of naked values to make
694 the source more readable. There are a lot of different ways to define and
695 use symbols and labels, giving a lot of flexibility.
697 <sect1>Numeric constants<p>
699 Numeric constants are defined using the equal sign or the label assignment
700 operator. After doing
706 may use the symbol "two" in every place where a number is expected, and it is
707 evaluated to the value 2 in this context. The label assignment operator is
708 almost identical, but causes the symbol to be marked as a label, so it may be
709 handled differently in a debugger:
715 The right side can of course be an expression:
722 <label id="variables">
723 <sect1>Numeric variables<p>
725 Within macros and other control structures (<tt><ref id=".REPEAT"
726 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
727 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
728 symbol that may get assigned a different value later:
732 lda #four ; Loads 4 into A
734 lda #four ; Loads 3 into A
737 Since the value of the symbol can change later, it must be possible to
738 evaluate it when used (no delayed evaluation as with normal symbols). So the
739 expression used as the value must be constant.
741 Following is an example for a macro that generates a different label each time
742 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
743 and a numeric variable named <tt>lcount</tt>.
746 .lcount .set 0 ; Initialize the counter
749 .ident (.sprintf ("L%04X", lcount)):
750 lcount .set lcount + 1
755 <sect1>Standard labels<p>
757 A label is defined by writing the name of the label at the start of the line
758 (before any instruction mnemonic, macro or pseudo directive), followed by a
759 colon. This will declare a symbol with the given name and the value of the
760 current program counter.
763 <sect1>Local labels and symbols<p>
765 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
766 create regions of code where the names of labels and symbols are local to this
767 region. They are not known outside of this region and cannot be accessed from
768 there. Such regions may be nested like PROCEDUREs in Pascal.
770 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
771 directive for more information.
774 <sect1>Cheap local labels<p>
776 Cheap local labels are defined like standard labels, but the name of the
777 label must begin with a special symbol (usually '@', but this can be
778 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
781 Cheap local labels are visible only between two non cheap labels. As soon as a
782 standard symbol is encountered (this may also be a local symbol if inside a
783 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
784 cheap local symbol goes out of scope.
786 You may use cheap local labels as an easy way to reuse common label
787 names like "Loop". Here is an example:
790 Clear: lda #$00 ; Global label
792 @Loop: sta Mem,y ; Local label
796 Sub: ... ; New global label
797 bne @Loop ; ERROR: Unknown identifier!
800 <sect1>Unnamed labels<p>
802 If you really want to write messy code, there are also unnamed labels. These
803 labels do not have a name (you guessed that already, didn't you?). A colon is
804 used to mark the absence of the name.
806 Unnamed labels may be accessed by using the colon plus several minus or plus
807 characters as a label designator. Using the '-' characters will create a back
808 reference (use the n'th label backwards), using '+' will create a forward
809 reference (use the n'th label in forward direction). An example will help to
832 As you can see from the example, unnamed labels will make even short
833 sections of code hard to understand, because you have to count labels
834 to find branch targets (this is the reason why I for my part do
835 prefer the "cheap" local labels). Nevertheless, unnamed labels are
836 convenient in some situations, so it's your decision.
838 <bf/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
839 unnamed ones, so scopes don't have an effect on unnamed labels.
843 <sect1>Using macros to define labels and constants<p>
845 While there are drawbacks with this approach, it may be handy in a few rare
846 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
847 to define symbols or constants that may be used elsewhere. One of the
848 advantages is that you can use it to define string constants (this is not
849 possible with the other symbol types).
851 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
852 so the names do not adhere to scoping, diagnostics may be misleading, there
853 are no symbols to look up in the map file, and there is no debug info.
854 Especially the first problem in the list can lead to very nasty programming
855 errors. Because of these problems, the general advice is, <bf/NOT/ do use
856 <tt/.DEFINE/ if you don't have to.
862 .DEFINE version "SOS V2.3"
864 four = two * two ; Ok
867 .PROC ; Start local scope
868 two = 3 ; Will give "2 = 3" - invalid!
873 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
875 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
876 id="option-g" name="-g"> is given on the command line), global, local and
877 cheap local labels are written to the object file and will be available in the
878 symbol file via the linker. Unnamed labels are not written to the object file,
879 because they don't have a name which would allow to access them.
883 <sect>Scopes<label id="scopes"><p>
885 ca65 implements several sorts of scopes for symbols.
887 <sect1>Global scope<p>
889 All (non cheap local) symbols that are declared outside of any nested scopes
893 <sect1>Cheap locals<p>
895 A special scope is the scope for cheap local symbols. It lasts from one non
896 local symbol to the next one, without any provisions made by the programmer.
897 All other scopes differ in usage but use the same concept internally.
900 <sect1>Generic nested scopes<p>
902 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
903 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
904 The scope can have a name, in which case it is accessible from the outside by
905 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
906 have a name, all symbols created within the scope are local to the scope, and
907 aren't accessible from the outside.
909 A nested scope can access symbols from the local or from enclosing scopes by
910 name without using explicit scope names. In some cases there may be
911 ambiguities, for example if there is a reference to a local symbol that is not
912 yet defined, but a symbol with the same name exists in outer scopes:
924 In the example above, the <tt/lda/ instruction will load the value 3 into the
925 accumulator, because <tt/foo/ is redefined in the scope. However:
937 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
938 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
939 absolute mode is used instead. In fact, the assembler will not use absolute
940 mode by default, but it will search through the enclosing scopes for a symbol
941 with the given name. If one is found, the address size of this symbol is used.
942 This may lead to errors:
954 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
955 instruction, it will search for an already defined symbol <tt/foo/. It will
956 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
957 zeropage symbol. So the assembler will use zeropage addressing mode. If
958 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
959 the address in the <tt/lda/ instruction already translated, but since the new
960 value needs absolute addressing mode, this fails, and an error message "Range
963 Of course the most simple solution for the problem is to move the definition
964 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
965 rare cases when this cannot be done. In these cases, you can use one of the
966 address size override operators:
978 This will cause the <tt/lda/ instruction to be translated using absolute
979 addressing mode, which means changing the symbol reference later does not
983 <sect1>Nested procedures<p>
985 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
986 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
987 name, and a it will introduce a symbol with this name in the enclosing scope.
996 is actually the same as
1005 This is the reason why a procedure must have a name. If you want a scope
1006 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
1008 <bf/Note:/ As you can see from the example above, scopes and symbols live in
1009 different namespaces. There can be a symbol named <tt/foo/ and a scope named
1010 <tt/foo/ without any conflicts (but see the section titled <ref
1011 id="scopesearch" name=""Scope search order"">).
1014 <sect1>Structs, unions and enums<p>
1016 Structs, unions and enums are explained in a <ref id="structs" name="separate
1017 section">, I do only cover them here, because if they are declared with a
1018 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
1019 name=".SCOPE">/. However, when no name is specified, the behaviour is
1020 different: In this case, no new scope will be opened, symbols declared within
1021 a struct, union, or enum declaration will then be added to the enclosing scope
1025 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1027 Accessing symbols from other scopes is possible by using an explicit scope
1028 specification, provided that the scope where the symbol lives in has a name.
1029 The namespace token (<tt/::/) is used to access other scopes:
1037 lda foo::bar ; Access foo in scope bar
1040 The only way to deny access to a scope from the outside is to declare a scope
1041 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1043 A special syntax is used to specify the global scope: If a symbol or scope is
1044 preceded by the namespace token, the global scope is searched:
1051 lda #::bar ; Access the global bar (which is 3)
1056 <sect1>Scope search order<label id="scopesearch"><p>
1058 The assembler searches for a scope in a similar way as for a symbol. First, it
1059 looks in the current scope, and then it walks up the enclosing scopes until
1062 However, one important thing to note when using explicit scope syntax is, that
1063 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1064 used without a preceding definition. This means that in the following
1073 lda #foo::bar ; Will load 3, not 2!
1080 the reference to the scope <tt/foo/ will use the global scope, and not the
1081 local one, because the local one is not visible at the point where it is
1084 Things get more complex if a complete chain of scopes is specified:
1095 lda #outer::inner::bar ; 1
1107 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1108 assembler will first search in the local scope for a scope named <tt/outer/.
1109 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1110 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1111 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1112 this scope, the assembler looks for a symbol named <tt/bar/.
1114 Please note that once the anchor scope is found, all following scopes
1115 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1116 assembler will search the scope tree only for the first scope (if it is not
1117 anchored in the root scope). Starting from there on, there is no flexibility,
1118 so if the scope named <tt/outer/ found by the assembler does not contain a
1119 scope named <tt/inner/, this would be an error, even if such a pair does exist
1120 (one level up in global scope).
1122 Ambiguities that may be introduced by this search algorithm may be removed by
1123 anchoring the scope specification in the global scope. In the example above,
1124 if you want to access the "other" symbol <tt/bar/, you would have to write:
1135 lda #::outer::inner::bar ; 2
1148 <sect>Address sizes and memory models<label id="address-sizes"><p>
1150 <sect1>Address sizes<p>
1152 ca65 assigns each segment and each symbol an address size. This is true, even
1153 if the symbol is not used as an address. You may also think of a value range
1154 of the symbol instead of an address size.
1156 Possible address sizes are:
1159 <item>Zeropage or direct (8 bits)
1160 <item>Absolute (16 bits)
1162 <item>Long (32 bits)
1165 Since the assembler uses default address sizes for the segments and symbols,
1166 it is usually not necessary to override the default behaviour. In cases, where
1167 it is necessary, the following keywords may be used to specify address sizes:
1170 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1171 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1172 <item>FAR for far addressing (24 bits).
1173 <item>LONG or DWORD for long addressing (32 bits).
1177 <sect1>Address sizes of segments<p>
1179 The assembler assigns an address size to each segment. Since the
1180 representation of a label within this segment is "segment start + offset",
1181 labels will inherit the address size of the segment they are declared in.
1183 The address size of a segment may be changed, by using an optional address
1184 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1185 an explanation on how this is done.
1188 <sect1>Address sizes of symbols<p>
1193 <sect1>Memory models<p>
1195 The default address size of a segment depends on the memory model used. Since
1196 labels inherit the address size from the segment they are declared in,
1197 changing the memory model is an easy way to change the address size of many
1203 <sect>Pseudo variables<label id="pseudo-variables"><p>
1205 Pseudo variables are readable in all cases, and in some special cases also
1208 <sect1><tt>*</tt><p>
1210 Reading this pseudo variable will return the program counter at the start
1211 of the current input line.
1213 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1214 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1215 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1218 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1220 Reading this pseudo variable will give a constant integer value that
1221 tells which CPU is currently enabled. It can also tell which instruction
1222 set the CPU is able to translate. The value read from the pseudo variable
1223 should be further examined by using one of the constants defined by the
1224 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1226 It may be used to replace the .IFPxx pseudo instructions or to construct
1227 even more complex expressions.
1233 .if (.cpu .bitand CPU_ISET_65816)
1245 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1247 This builtin pseudo variable is only available in macros. It is replaced by
1248 the actual number of parameters that were given in the macro invocation.
1253 .macro foo arg1, arg2, arg3
1254 .if .paramcount <> 3
1255 .error "Too few parameters for macro foo"
1261 See section <ref id="macros" name="Macros">.
1264 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1266 Reading this pseudo variable will give a constant integer value that
1267 represents the current time in POSIX standard (as seconds since the
1270 It may be used to encode the time of translation somewhere in the created
1276 .dword .time ; Place time here
1280 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1282 Reading this pseudo variable will give the assembler version according to
1283 the following formula:
1285 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1287 It may be used to encode the assembler version or check the assembler for
1288 special features not available with older versions.
1292 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1293 reading the pseudo variable <tt/.VERSION/.
1297 <sect>Pseudo functions<label id="pseudo-functions"><p>
1299 Pseudo functions expect their arguments in parenthesis, and they have a result,
1300 either a string or an expression.
1303 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1305 The <tt/.BANK/ function is used to support systems with banked memory. The
1306 argument is an expression with exactly one segment reference - usually a
1307 label. The function result is the value of the <tt/bank/ attribute assigned
1308 to the run memory area of the segment. Please see the linker documentation
1309 for more information about memory areas and their attributes.
1311 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1312 containing specific data is available.
1314 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1315 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1316 name=".LOBYTE"></tt> or similar functions to address just part of it.
1318 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1319 an expression containing <tt/.BANK/ can never be used where a constant known
1320 result is expected (for example with <tt/.RES/).
1337 .byte <.BANK (banked_func_1)
1340 .byte <.BANK (banked_func_2)
1346 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1348 The function returns the bank byte (that is, bits 16-23) of its argument.
1349 It works identical to the '^' operator.
1351 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1352 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1355 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1357 Builtin function. The function evaluates its argument in braces and yields
1358 "false" if the argument is non blank (there is an argument), and "true" if
1359 there is no argument. The token list that makes up the function argument
1360 may optionally be enclosed in curly braces. This allows the inclusion of
1361 tokens that would otherwise terminate the list (the closing right
1362 parenthesis). The curly braces are not considered part of the list, a list
1363 just consisting of curly braces is considered to be empty.
1365 As an example, the <tt/.IFBLANK/ statement may be replaced by
1373 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1375 Builtin string function. The function allows to concatenate a list of string
1376 constants separated by commas. The result is a string constant that is the
1377 concatenation of all arguments. This function is most useful in macros and
1378 when used together with the <tt/.STRING/ builtin function. The function may
1379 be used in any case where a string constant is expected.
1384 .include .concat ("myheader", ".", "inc")
1387 This is the same as the command
1390 .include "myheader.inc"
1394 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1396 Builtin function. The function evaluates its argument in braces and
1397 yields "true" if the argument is a constant expression (that is, an
1398 expression that yields a constant value at assembly time) and "false"
1399 otherwise. As an example, the .IFCONST statement may be replaced by
1406 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1408 The function returns the high byte (that is, bits 8-15) of its argument.
1409 It works identical to the '>' operator.
1411 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1412 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1415 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1417 The function returns the high word (that is, bits 16-31) of its argument.
1419 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1422 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1424 The function expects a string as its argument, and converts this argument
1425 into an identifier. If the string starts with the current <tt/<ref
1426 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1427 identifier, otherwise it will be converted into a normal identifier.
1432 .macro makelabel arg1, arg2
1433 .ident (.concat (arg1, arg2)):
1436 makelabel "foo", "bar"
1438 .word foobar ; Valid label
1442 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1444 Builtin function. Extracts the left part of a given token list.
1449 .LEFT (<int expr>, <token list>)
1452 The first integer expression gives the number of tokens to extract from
1453 the token list. The second argument is the token list itself. The token
1454 list may optionally be enclosed into curly braces. This allows the
1455 inclusion of tokens that would otherwise terminate the list (the closing
1456 right paren in the given case).
1460 To check in a macro if the given argument has a '#' as first token
1461 (immediate addressing mode), use something like this:
1466 .if (.match (.left (1, {arg}), #))
1468 ; ldax called with immediate operand
1476 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1477 name=".RIGHT"></tt> builtin functions.
1480 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1482 The function returns the low byte (that is, bits 0-7) of its argument.
1483 It works identical to the '<' operator.
1485 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1486 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1489 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1491 The function returns the low word (that is, bits 0-15) of its argument.
1493 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1496 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1498 Builtin function. Matches two token lists against each other. This is
1499 most useful within macros, since macros are not stored as strings, but
1505 .MATCH(<token list #1>, <token list #2>)
1508 Both token list may contain arbitrary tokens with the exception of the
1509 terminator token (comma resp. right parenthesis) and
1516 The token lists may optionally be enclosed into curly braces. This allows
1517 the inclusion of tokens that would otherwise terminate the list (the closing
1518 right paren in the given case). Often a macro parameter is used for any of
1521 Please note that the function does only compare tokens, not token
1522 attributes. So any number is equal to any other number, regardless of the
1523 actual value. The same is true for strings. If you need to compare tokens
1524 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1525 name=".XMATCH"></tt> function.
1529 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1530 while honoring the sign bit. The builtin processor instructions will allow
1531 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1532 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1533 to check for this and print and error for invalid calls.
1538 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1539 .error "Syntax error"
1542 cmp #$80 ; Bit 7 into carry
1543 lsr a ; Shift carry into bit 7
1548 The macro will only accept no arguments, or one argument that must be the
1549 reserved keyword "A".
1551 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1554 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1556 Builtin function. The result is the larger of two values.
1561 .MAX (<value #1>, <value #2>)
1567 ; Reserve space for the larger of two data blocks
1568 savearea: .max (.sizeof (foo), .sizeof (bar))
1571 See: <tt><ref id=".MIN" name=".MIN"></tt>
1574 <sect1><tt>.MID</tt><label id=".MID"><p>
1576 Builtin function. Takes a starting index, a count and a token list as
1577 arguments. Will return part of the token list.
1582 .MID (<int expr>, <int expr>, <token list>)
1585 The first integer expression gives the starting token in the list (the first
1586 token has index 0). The second integer expression gives the number of tokens
1587 to extract from the token list. The third argument is the token list itself.
1588 The token list may optionally be enclosed into curly braces. This allows the
1589 inclusion of tokens that would otherwise terminate the list (the closing
1590 right paren in the given case).
1594 To check in a macro if the given argument has a '<tt/#/' as first token
1595 (immediate addressing mode), use something like this:
1600 .if (.match (.mid (0, 1, {arg}), #))
1602 ; ldax called with immediate operand
1610 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1611 name=".RIGHT"></tt> builtin functions.
1614 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1616 Builtin function. The result is the smaller of two values.
1621 .MIN (<value #1>, <value #2>)
1627 ; Reserve space for some data, but 256 bytes minimum
1628 savearea: .min (.sizeof (foo), 256)
1631 See: <tt><ref id=".MAX" name=".MAX"></tt>
1634 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1636 Builtin function. The function expects an identifier as argument in braces.
1637 The argument is evaluated, and the function yields "true" if the identifier
1638 is a symbol that has already been referenced somewhere in the source file up
1639 to the current position. Otherwise the function yields false. As an example,
1640 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1646 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1649 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1651 Builtin function. Extracts the right part of a given token list.
1656 .RIGHT (<int expr>, <token list>)
1659 The first integer expression gives the number of tokens to extract from the
1660 token list. The second argument is the token list itself. The token list
1661 may optionally be enclosed into curly braces. This allows the inclusion of
1662 tokens that would otherwise terminate the list (the closing right paren in
1665 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1666 name=".MID"></tt> builtin functions.
1669 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1671 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1672 argument can be a struct/union, a struct member, a procedure, or a label. In
1673 case of a procedure or label, its size is defined by the amount of data
1674 placed in the segment where the label is relative to. If a line of code
1675 switches segments (for example in a macro) data placed in other segments
1676 does not count for the size.
1678 Please note that a symbol or scope must exist, before it is used together with
1679 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1680 A scope has preference over a symbol with the same name, so if the last part
1681 of a name represents both, a scope and a symbol, the scope is chosen over the
1684 After the following code:
1687 .struct Point ; Struct size = 4
1692 P: .tag Point ; Declare a point
1693 @P: .tag Point ; Declare another point
1705 .data ; Segment switch!!!
1711 <tag><tt/.sizeof(Point)/</tag>
1712 will have the value 4, because this is the size of struct <tt/Point/.
1714 <tag><tt/.sizeof(Point::xcoord)/</tag>
1715 will have the value 2, because this is the size of the member <tt/xcoord/
1716 in struct <tt/Point/.
1718 <tag><tt/.sizeof(P)/</tag>
1719 will have the value 4, this is the size of the data declared on the same
1720 source line as the label <tt/P/, which is in the same segment that <tt/P/
1723 <tag><tt/.sizeof(@P)/</tag>
1724 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1725 does also work for cheap local symbols.
1727 <tag><tt/.sizeof(Code)/</tag>
1728 will have the value 3, since this is amount of data emitted into the code
1729 segment, the segment that was active when <tt/Code/ was entered. Note that
1730 this value includes the amount of data emitted in child scopes (in this
1731 case <tt/Code::Inner/).
1733 <tag><tt/.sizeof(Code::Inner)/</tag>
1734 will have the value 1 as expected.
1736 <tag><tt/.sizeof(Data)/</tag>
1737 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1738 the segment is switched after entry, this data is emitted into another
1743 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1745 Builtin function. The function accepts a string and an index as
1746 arguments and returns the value of the character at the given position
1747 as an integer value. The index is zero based.
1753 ; Check if the argument string starts with '#'
1754 .if (.strat (Arg, 0) = '#')
1761 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1763 Builtin function. It expects a format string as first argument. The number
1764 and type of the following arguments depend on the format string. The format
1765 string is similar to the one of the C <tt/printf/ function. Missing things
1766 are: Length modifiers, variable width.
1768 The result of the function is a string.
1775 ; Generate an identifier:
1776 .ident (.sprintf ("%s%03d", "label", num)):
1780 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1782 Builtin function. The function accepts an argument in braces and converts
1783 this argument into a string constant. The argument may be an identifier, or
1784 a constant numeric value.
1786 Since you can use a string in the first place, the use of the function may
1787 not be obvious. However, it is useful in macros, or more complex setups.
1792 ; Emulate other assemblers:
1794 .segment .string(name)
1799 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1801 Builtin function. The function accepts a string argument in braces and
1802 evaluates to the length of the string.
1806 The following macro encodes a string as a pascal style string with
1807 a leading length byte.
1811 .byte .strlen(Arg), Arg
1816 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1818 Builtin function. The function accepts a token list in braces. The function
1819 result is the number of tokens given as argument. The token list may
1820 optionally be enclosed into curly braces which are not considered part of
1821 the list and not counted. Enclosement in curly braces allows the inclusion
1822 of tokens that would otherwise terminate the list (the closing right paren
1827 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1828 with the normal 6502 instructions). To translate it into two separate 8 bit
1829 load instructions, the '#' token has to get stripped from the argument:
1833 .if (.match (.mid (0, 1, {arg}), #))
1834 ; ldax called with immediate operand
1835 lda #<(.right (.tcount ({arg})-1, {arg}))
1836 ldx #>(.right (.tcount ({arg})-1, {arg}))
1844 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1846 Builtin function. Matches two token lists against each other. This is
1847 most useful within macros, since macros are not stored as strings, but
1853 .XMATCH(<token list #1>, <token list #2>)
1856 Both token list may contain arbitrary tokens with the exception of the
1857 terminator token (comma resp. right parenthesis) and
1864 The token lists may optionally be enclosed into curly braces. This allows
1865 the inclusion of tokens that would otherwise terminate the list (the closing
1866 right paren in the given case). Often a macro parameter is used for any of
1869 The function compares tokens <em/and/ token values. If you need a function
1870 that just compares the type of tokens, have a look at the <tt><ref
1871 id=".MATCH" name=".MATCH"></tt> function.
1873 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1877 <sect>Control commands<label id="control-commands"><p>
1879 Here's a list of all control commands and a description, what they do:
1882 <sect1><tt>.A16</tt><label id=".A16"><p>
1884 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1886 Note: This command will not emit any code, it will tell the assembler to
1887 create 16 bit operands for immediate accumulator addressing mode.
1889 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1892 <sect1><tt>.A8</tt><label id=".A8"><p>
1894 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1896 Note: This command will not emit any code, it will tell the assembler to
1897 create 8 bit operands for immediate accu addressing mode.
1899 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1902 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1904 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1905 may be used for better readability if the data words are address values. In
1906 65816 mode, the address is forced to be 16 bit wide to fit into the current
1907 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1908 must be followed by a sequence of (not necessarily constant) expressions.
1913 .addr $0D00, $AF13, _Clear
1916 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1920 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1922 Align data to a given boundary. The command expects a constant integer
1923 argument in the range 1 ... 65536, plus an optional second argument
1924 in byte range. If there is a second argument, it is used as fill value,
1925 otherwise the value defined in the linker configuration file is used
1926 (the default for this value is zero).
1928 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1929 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1930 number of bytes, since that would break address calculations within the
1931 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1932 of the alignment, because that allows the number of fill bytes to be
1933 calculated in advance by the assembler. You are therefore required to
1934 specify a matching alignment for the segment in the linker config. The
1935 linker will output a warning if the alignment of the segment is less than
1936 what is necessary to have a correct alignment in the object file.
1944 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1945 commands with different arguments. To allow the assembler to calculate the
1946 number of fill bytes in advance, the alignment of the segment must be a
1947 multiple of each of the alignment factors. This may result in unexpectedly
1948 large alignments for the segment within the module.
1959 For the assembler to be able to align correctly, the segment must be aligned
1960 to the least common multiple of 15 and 18 which is 90. The assembler will
1961 calculate this automatically and will mark the segment with this value.
1963 Unfortunately, the combined alignment may get rather large without the user
1964 knowing about it, wasting space in the final executable. If we add another
1965 alignment to the example above
1976 the assembler will force a segment alignment to the least common multiple of
1977 15, 18 and 251 - which is 22590. To protect the user against errors, the
1978 assembler will issue a warning when the combined alignment exceeds 256. The
1979 command line option <tt><ref id="option--large-alignment"
1980 name="--large-alignment"></tt> will disable this warning.
1982 Please note that with alignments that are a power of two (which were the
1983 only alignments possible in older versions of the assembler), the problem is
1984 less severe, because the least common multiple of powers to the same base is
1985 always the larger one.
1989 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1991 Define a string with a trailing zero.
1996 Msg: .asciiz "Hello world"
1999 This will put the string "Hello world" followed by a binary zero into
2000 the current segment. There may be more strings separated by commas, but
2001 the binary zero is only appended once (after the last one).
2004 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2006 Add an assertion. The command is followed by an expression, an action
2007 specifier, and an optional message that is output in case the assertion
2008 fails. If no message was given, the string "Assertion failed" is used. The
2009 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2010 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2011 assembler if possible, and in any case, it's also passed to the linker in
2012 the object file (if one is generated). The linker will then evaluate the
2013 expression when segment placement has been done.
2018 .assert * = $8000, error, "Code not at $8000"
2021 The example assertion will check that the current location is at $8000,
2022 when the output file is written, and abort with an error if this is not
2023 the case. More complex expressions are possible. The action specifier
2024 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2025 an error message. In the latter case, generation of the output file is
2026 suppressed in both the assembler and linker.
2029 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2031 Is followed by a plus or a minus character. When switched on (using a
2032 +), undefined symbols are automatically marked as import instead of
2033 giving errors. When switched off (which is the default so this does not
2034 make much sense), this does not happen and an error message is
2035 displayed. The state of the autoimport flag is evaluated when the
2036 complete source was translated, before outputting actual code, so it is
2037 <em/not/ possible to switch this feature on or off for separate sections
2038 of code. The last setting is used for all symbols.
2040 You should probably not use this switch because it delays error
2041 messages about undefined symbols until the link stage. The cc65
2042 compiler (which is supposed to produce correct assembler code in all
2043 circumstances, something which is not true for most assembler
2044 programmers) will insert this command to avoid importing each and every
2045 routine from the runtime library.
2050 .autoimport + ; Switch on auto import
2053 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2055 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2056 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2057 the operator '^' prepended to each expression in its list.
2062 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2064 TableLookupLo: .lobytes MyTable
2065 TableLookupHi: .hibytes MyTable
2066 TableLookupBank: .bankbytes MyTable
2069 which is equivalent to
2072 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2073 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2074 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2077 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2078 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2079 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2082 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2084 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2085 so this is a shortcut for
2091 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2094 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2096 Define byte sized data. Must be followed by a sequence of (byte ranged)
2097 expressions or strings.
2103 .byt "world", $0D, $00
2107 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2109 Switch on or off case sensitivity on identifiers. The default is off
2110 (that is, identifiers are case sensitive), but may be changed by the
2111 -i switch on the command line.
2112 The command must be followed by a '+' or '-' character to switch the
2113 option on or off respectively.
2118 .case - ; Identifiers are not case sensitive
2122 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2124 Apply a custom mapping for characters. The command is followed by two
2125 numbers in the range 1..255. The first one is the index of the source
2126 character, the second one is the mapping. The mapping applies to all
2127 character and string constants when they generate output, and overrides
2128 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2129 command line switch.
2134 .charmap $41, $61 ; Map 'A' to 'a'
2138 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2140 Switch to the CODE segment. The name of the CODE segment is always
2141 "CODE", so this is a shortcut for
2147 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2150 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2152 Export a symbol and mark it in a special way. The linker is able to build
2153 tables of all such symbols. This may be used to automatically create a list
2154 of functions needed to initialize linked library modules.
2156 Note: The linker has a feature to build a table of marked routines, but it
2157 is your code that must call these routines, so just declaring a symbol with
2158 <tt/.CONDES/ does nothing by itself.
2160 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2161 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2162 is implied by <tt/.CONDES/.
2164 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2165 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2166 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2167 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2168 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2169 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2170 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2172 After the type, an optional priority may be specified. Higher numeric values
2173 mean higher priority. If no priority is given, the default priority of 7 is
2174 used. Be careful when assigning priorities to your own module constructors
2175 so they won't interfere with the ones in the cc65 library.
2180 .condes ModuleInit, constructor
2181 .condes ModInit, 0, 16
2184 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2185 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2186 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2187 name="Module constructors/destructors"> explaining the feature in more
2191 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2193 Export a symbol and mark it as a module constructor. This may be used
2194 together with the linker to build a table of constructor subroutines that
2195 are called by the startup code.
2197 Note: The linker has a feature to build a table of marked routines, but it
2198 is your code that must call these routines, so just declaring a symbol as
2199 constructor does nothing by itself.
2201 A constructor is always exported as an absolute (16 bit) symbol. You don't
2202 need to use an additional <tt/.export/ statement, this is implied by
2203 <tt/.constructor/. It may have an optional priority that is separated by a
2204 comma. Higher numeric values mean a higher priority. If no priority is
2205 given, the default priority of 7 is used. Be careful when assigning
2206 priorities to your own module constructors so they won't interfere with the
2207 ones in the cc65 library.
2212 .constructor ModuleInit
2213 .constructor ModInit, 16
2216 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2217 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2218 <ref id="condes" name="Module constructors/destructors"> explaining the
2219 feature in more detail.
2222 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2224 Switch to the DATA segment. The name of the DATA segment is always
2225 "DATA", so this is a shortcut for
2231 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2234 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2236 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2237 create word sized data in native 65XX format). Must be followed by a
2238 sequence of (word ranged) expressions.
2246 This will emit the bytes
2252 into the current segment in that order.
2255 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2257 Switch on or off debug info generation. The default is off (that is,
2258 the object file will not contain debug infos), but may be changed by the
2259 -g switch on the command line.
2260 The command must be followed by a '+' or '-' character to switch the
2261 option on or off respectively.
2266 .debuginfo + ; Generate debug info
2270 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2272 Start a define style macro definition. The command is followed by an
2273 identifier (the macro name) and optionally by a list of formal arguments
2276 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2277 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2280 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2281 section <ref id="macros" name="Macros">.
2284 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2286 Delete a classic macro (defined with <tt><ref id=".MACRO"
2287 name=".MACRO"></tt>) . The command is followed by the name of an
2288 existing macro. Its definition will be deleted together with the name.
2289 If necessary, another macro with this name may be defined later.
2291 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2292 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2293 <tt><ref id=".MACRO" name=".MACRO"></tt>
2295 See also section <ref id="macros" name="Macros">.
2298 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2300 Builtin function. The function expects an identifier as argument in braces.
2301 The argument is evaluated, and the function yields "true" if the identifier
2302 is a symbol that is already defined somewhere in the source file up to the
2303 current position. Otherwise the function yields false. As an example, the
2304 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2311 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2313 Export a symbol and mark it as a module destructor. This may be used
2314 together with the linker to build a table of destructor subroutines that
2315 are called by the startup code.
2317 Note: The linker has a feature to build a table of marked routines, but it
2318 is your code that must call these routines, so just declaring a symbol as
2319 constructor does nothing by itself.
2321 A destructor is always exported as an absolute (16 bit) symbol. You don't
2322 need to use an additional <tt/.export/ statement, this is implied by
2323 <tt/.destructor/. It may have an optional priority that is separated by a
2324 comma. Higher numerical values mean a higher priority. If no priority is
2325 given, the default priority of 7 is used. Be careful when assigning
2326 priorities to your own module destructors so they won't interfere with the
2327 ones in the cc65 library.
2332 .destructor ModuleDone
2333 .destructor ModDone, 16
2336 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2337 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2338 section <ref id="condes" name="Module constructors/destructors"> explaining
2339 the feature in more detail.
2342 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2344 Define dword sized data (4 bytes) Must be followed by a sequence of
2350 .dword $12344512, $12FA489
2354 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2356 Conditional assembly: Reverse the current condition.
2359 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2361 Conditional assembly: Reverse current condition and test a new one.
2364 <sect1><tt>.END</tt><label id=".END"><p>
2366 Forced end of assembly. Assembly stops at this point, even if the command
2367 is read from an include file.
2370 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2372 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2375 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2377 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2378 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2381 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2383 Marks the end of a macro definition.
2385 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2386 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2387 <tt><ref id=".MACRO" name=".MACRO"></tt>
2389 See also section <ref id="macros" name="Macros">.
2392 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2394 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2397 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2399 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2402 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2404 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2407 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2409 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2410 command and the separate section named <ref id="structs" name=""Structs
2414 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2416 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2417 command and the separate section named <ref id="structs" name=""Structs
2421 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2423 Start an enumeration. This directive is very similar to the C <tt/enum/
2424 keyword. If a name is given, a new scope is created for the enumeration,
2425 otherwise the enumeration members are placed in the enclosing scope.
2427 In the enumeration body, symbols are declared. The first symbol has a value
2428 of zero, and each following symbol will get the value of the preceding plus
2429 one. This behaviour may be overridden by an explicit assignment. Two symbols
2430 may have the same value.
2442 Above example will create a new scope named <tt/errorcodes/ with three
2443 symbols in it that get the values 0, 1 and 2 respectively. Another way
2444 to write this would have been:
2454 Please note that explicit scoping must be used to access the identifiers:
2457 .word errorcodes::no_error
2460 A more complex example:
2469 EWOULDBLOCK = EAGAIN
2473 In this example, the enumeration does not have a name, which means that the
2474 members will be visible in the enclosing scope and can be used in this scope
2475 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2476 The value for the following members is incremented by one, so <tt/EOK/ would
2477 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2478 override for the value using an already defined symbol.
2481 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2483 Force an assembly error. The assembler will output an error message
2484 preceded by "User error". Assembly is continued but no object file will
2487 This command may be used to check for initial conditions that must be
2488 set before assembling a source file.
2498 .error "Must define foo or bar!"
2502 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2503 <tt><ref id=".OUT" name=".OUT"></tt>,
2504 <tt><ref id=".WARNING" name=".WARNING"></tt>
2507 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2509 Abort a macro expansion immediately. This command is often useful in
2512 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2513 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2514 <tt><ref id=".MACRO" name=".MACRO"></tt>
2516 See also section <ref id="macros" name="Macros">.
2519 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2521 Make symbols accessible from other modules. Must be followed by a comma
2522 separated list of symbols to export, with each one optionally followed by an
2523 address specification and (also optional) an assignment. Using an additional
2524 assignment in the export statement allows to define and export a symbol in
2525 one statement. The default is to export the symbol with the address size it
2526 actually has. The assembler will issue a warning, if the symbol is exported
2527 with an address size smaller than the actual address size.
2534 .export foobar: far = foo * bar
2535 .export baz := foobar, zap: far = baz - bar
2538 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2541 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2544 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2546 Make symbols accessible from other modules. Must be followed by a comma
2547 separated list of symbols to export. The exported symbols are explicitly
2548 marked as zero page symbols. An assignment may be included in the
2549 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2556 .exportzp baz := $02
2559 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2562 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2564 Define far (24 bit) address data. The command must be followed by a
2565 sequence of (not necessarily constant) expressions.
2570 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2573 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2576 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2578 Force an assembly error and terminate assembly. The assembler will output an
2579 error message preceded by "User error" and will terminate assembly
2582 This command may be used to check for initial conditions that must be
2583 set before assembling a source file.
2593 .fatal "Must define foo or bar!"
2597 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2598 <tt><ref id=".OUT" name=".OUT"></tt>,
2599 <tt><ref id=".WARNING" name=".WARNING"></tt>
2602 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2604 This directive may be used to enable one or more compatibility features
2605 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2606 possible, it may be useful when porting sources written for other
2607 assemblers. There is no way to switch a feature off, once you have
2608 enabled it, so using
2614 will enable the feature until end of assembly is reached.
2616 The following features are available:
2620 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2622 Accept the at character (`@') as a valid character in identifiers. The
2623 at character is not allowed to start an identifier, even with this
2626 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2628 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2629 comment terminators. Note that C comments may not be nested. There's also a
2630 pitfall when using C like comments: All statements must be terminated by
2631 "end-of-line". Using C like comments, it is possible to hide the newline,
2632 which results in error messages. See the following non working example:
2635 lda #$00 /* This comment hides the newline
2639 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2641 Accept the dollar sign (`$') as a valid character in identifiers. The
2642 dollar character is not allowed to start an identifier, even with this
2645 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2647 The dollar sign may be used as an alias for the star (`*'), which
2648 gives the value of the current PC in expressions.
2649 Note: Assignment to the pseudo variable is not allowed.
2651 <tag><tt>force_range</tt><label id="force_range"></tag>
2653 Force expressions into their valid range for immediate addressing and
2654 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2655 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2656 since it will completely disable error checks.
2658 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2660 Allow labels without a trailing colon. These labels are only accepted,
2661 if they start at the beginning of a line (no leading white space).
2663 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2665 Accept the dot (`.') as the first character of an identifier. This may be
2666 used for example to create macro names that start with a dot emulating
2667 control directives of other assemblers. Note however, that none of the
2668 reserved keywords built into the assembler, that starts with a dot, may be
2669 overridden. When using this feature, you may also get into trouble if
2670 later versions of the assembler define new keywords starting with a dot.
2672 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2674 Accept single quotes as well as double quotes as terminators for char
2677 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2679 Accept single quotes as well as double quotes as terminators for string
2682 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2684 Accept single quoted character constants where the terminating quote is
2689 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2690 loose_string_term/, since in this case the input would be ambiguous.
2692 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2694 This feature makes relocatable/absolute mode local to the current segment.
2695 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2696 effect will only enable absolute mode for the current segment. Dito for
2697 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2699 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2701 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2702 is enabled). Such an assignment is handled identical to the <tt><ref
2703 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2704 removing the lines with the assignments may also be an option when porting
2705 code written for older assemblers).
2707 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2709 Allow the use of instructions names as names for macros and symbols. This
2710 makes it possible to "overload" instructions by defining a macro with the
2711 same name. This does also make it possible to introduce hard to find errors
2712 in your code, so be careful!
2716 It is also possible to specify features on the command line using the
2717 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2718 This is useful when translating sources written for older assemblers, when
2719 you don't want to change the source code.
2721 As an example, to translate sources written for Andre Fachats xa65
2722 assembler, the features
2725 labels_without_colons, pc_assignment, loose_char_term
2728 may be helpful. They do not make ca65 completely compatible, so you may not
2729 be able to translate the sources without changes, even when enabling these
2730 features. However, I have found several sources that translate without
2731 problems when enabling these features on the command line.
2734 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2736 Insert an option string into the object file. There are two forms of
2737 this command, one specifies the option by a keyword, the second
2738 specifies it as a number. Since usage of the second one needs knowledge
2739 of the internal encoding, its use is not recommended and I will only
2740 describe the first form here.
2742 The command is followed by one of the keywords
2750 a comma and a string. The option is written into the object file
2751 together with the string value. This is currently unidirectional and
2752 there is no way to actually use these options once they are in the
2758 .fileopt comment, "Code stolen from my brother"
2759 .fileopt compiler, "BASIC 2.0"
2760 .fopt author, "J. R. User"
2764 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2766 Import an absolute symbol from another module. The command is followed by a
2767 comma separated list of symbols to import. The command is similar to <tt>
2768 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2769 written to the generated object file, even if the symbol is never referenced
2770 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2771 references for unused symbols).
2776 .forceimport needthisone, needthistoo
2779 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2782 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2784 Declare symbols as global. Must be followed by a comma separated list of
2785 symbols to declare. Symbols from the list, that are defined somewhere in the
2786 source, are exported, all others are imported. Additional <tt><ref
2787 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2788 name=".EXPORT"></tt> commands for the same symbol are allowed.
2797 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2799 Declare symbols as global. Must be followed by a comma separated list of
2800 symbols to declare. Symbols from the list, that are defined somewhere in the
2801 source, are exported, all others are imported. Additional <tt><ref
2802 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2803 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2804 in the list are explicitly marked as zero page symbols.
2812 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2814 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2815 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2816 the operator '>' prepended to each expression in its list.
2821 .lobytes $1234, $2345, $3456, $4567
2822 .hibytes $fedc, $edcb, $dcba, $cba9
2825 which is equivalent to
2828 .byte $34, $45, $56, $67
2829 .byte $fe, $ed, $dc, $cb
2835 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2837 TableLookupLo: .lobytes MyTable
2838 TableLookupHi: .hibytes MyTable
2841 which is equivalent to
2844 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2845 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2848 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2849 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2850 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2853 <sect1><tt>.I16</tt><label id=".I16"><p>
2855 Valid only in 65816 mode. Switch the index registers to 16 bit.
2857 Note: This command will not emit any code, it will tell the assembler to
2858 create 16 bit operands for immediate operands.
2860 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2861 name=".SMART"></tt> commands.
2864 <sect1><tt>.I8</tt><label id=".I8"><p>
2866 Valid only in 65816 mode. Switch the index registers to 8 bit.
2868 Note: This command will not emit any code, it will tell the assembler to
2869 create 8 bit operands for immediate operands.
2871 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2872 name=".SMART"></tt> commands.
2875 <sect1><tt>.IF</tt><label id=".IF"><p>
2877 Conditional assembly: Evaluate an expression and switch assembler output
2878 on or off depending on the expression. The expression must be a constant
2879 expression, that is, all operands must be defined.
2881 A expression value of zero evaluates to FALSE, any other value evaluates
2885 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2887 Conditional assembly: Check if there are any remaining tokens in this line,
2888 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2889 condition is not true, further lines are not assembled until an <tt><ref
2890 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2891 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2893 This command is often used to check if a macro parameter was given. Since an
2894 empty macro parameter will evaluate to nothing, the condition will evaluate
2895 to TRUE if an empty parameter was given.
2909 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2912 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2914 Conditional assembly: Evaluate an expression and switch assembler output
2915 on or off depending on the constness of the expression.
2917 A const expression evaluates to to TRUE, a non const expression (one
2918 containing an imported or currently undefined symbol) evaluates to
2921 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2924 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2926 Conditional assembly: Check if a symbol is defined. Must be followed by
2927 a symbol name. The condition is true if the the given symbol is already
2928 defined, and false otherwise.
2930 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2933 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2935 Conditional assembly: Check if there are any remaining tokens in this line,
2936 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2937 condition is not true, further lines are not assembled until an <tt><ref
2938 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2939 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2941 This command is often used to check if a macro parameter was given.
2942 Since an empty macro parameter will evaluate to nothing, the condition
2943 will evaluate to FALSE if an empty parameter was given.
2956 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2959 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2961 Conditional assembly: Check if a symbol is defined. Must be followed by
2962 a symbol name. The condition is true if the the given symbol is not
2963 defined, and false otherwise.
2965 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2968 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2970 Conditional assembly: Check if a symbol is referenced. Must be followed
2971 by a symbol name. The condition is true if if the the given symbol was
2972 not referenced before, and false otherwise.
2974 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2977 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2979 Conditional assembly: Check if the assembler is currently in 6502 mode
2980 (see <tt><ref id=".P02" name=".P02"></tt> command).
2983 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2985 Conditional assembly: Check if the assembler is currently in 65816 mode
2986 (see <tt><ref id=".P816" name=".P816"></tt> command).
2989 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2991 Conditional assembly: Check if the assembler is currently in 65C02 mode
2992 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2995 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2997 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2998 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3001 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3003 Conditional assembly: Check if a symbol is referenced. Must be followed
3004 by a symbol name. The condition is true if if the the given symbol was
3005 referenced before, and false otherwise.
3007 This command may be used to build subroutine libraries in include files
3008 (you may use separate object modules for this purpose too).
3013 .ifref ToHex ; If someone used this subroutine
3014 ToHex: tay ; Define subroutine
3020 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3023 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3025 Import a symbol from another module. The command is followed by a comma
3026 separated list of symbols to import, with each one optionally followed by
3027 an address specification.
3033 .import bar: zeropage
3036 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3039 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3041 Import a symbol from another module. The command is followed by a comma
3042 separated list of symbols to import. The symbols are explicitly imported
3043 as zero page symbols (that is, symbols with values in byte range).
3051 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3054 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3056 Include a file as binary data. The command expects a string argument
3057 that is the name of a file to include literally in the current segment.
3058 In addition to that, a start offset and a size value may be specified,
3059 separated by commas. If no size is specified, all of the file from the
3060 start offset to end-of-file is used. If no start position is specified
3061 either, zero is assumed (which means that the whole file is inserted).
3066 ; Include whole file
3067 .incbin "sprites.dat"
3069 ; Include file starting at offset 256
3070 .incbin "music.dat", $100
3072 ; Read 100 bytes starting at offset 200
3073 .incbin "graphics.dat", 200, 100
3077 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3079 Include another file. Include files may be nested up to a depth of 16.
3088 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3090 Export a symbol and mark it as an interruptor. This may be used together
3091 with the linker to build a table of interruptor subroutines that are called
3094 Note: The linker has a feature to build a table of marked routines, but it
3095 is your code that must call these routines, so just declaring a symbol as
3096 interruptor does nothing by itself.
3098 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3099 need to use an additional <tt/.export/ statement, this is implied by
3100 <tt/.interruptor/. It may have an optional priority that is separated by a
3101 comma. Higher numeric values mean a higher priority. If no priority is
3102 given, the default priority of 7 is used. Be careful when assigning
3103 priorities to your own module constructors so they won't interfere with the
3104 ones in the cc65 library.
3109 .interruptor IrqHandler
3110 .interruptor Handler, 16
3113 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3114 section <ref id="condes" name="Module constructors/destructors"> explaining
3115 the feature in more detail.
3118 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3120 Switch on or off line continuations using the backslash character
3121 before a newline. The option is off by default.
3122 Note: Line continuations do not work in a comment. A backslash at the
3123 end of a comment is treated as part of the comment and does not trigger
3125 The command must be followed by a '+' or '-' character to switch the
3126 option on or off respectively.
3131 .linecont + ; Allow line continuations
3134 #$20 ; This is legal now
3138 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3140 Enable output to the listing. The command must be followed by a boolean
3141 switch ("on", "off", "+" or "-") and will enable or disable listing
3143 The option has no effect if the listing is not enabled by the command line
3144 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3145 to the listing file, if the counter is greater than zero, and suppressed if
3146 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3152 .list on ; Enable listing output
3156 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3158 Set, how many bytes are shown in the listing for one source line. The
3159 default is 12, so the listing will show only the first 12 bytes for any
3160 source line that generates more than 12 bytes of code or data.
3161 The directive needs an argument, which is either "unlimited", or an
3162 integer constant in the range 4..255.
3167 .listbytes unlimited ; List all bytes
3168 .listbytes 12 ; List the first 12 bytes
3169 .incbin "data.bin" ; Include large binary file
3173 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3175 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3176 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3177 the operator '<' prepended to each expression in its list.
3182 .lobytes $1234, $2345, $3456, $4567
3183 .hibytes $fedc, $edcb, $dcba, $cba9
3186 which is equivalent to
3189 .byte $34, $45, $56, $67
3190 .byte $fe, $ed, $dc, $cb
3196 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3198 TableLookupLo: .lobytes MyTable
3199 TableLookupHi: .hibytes MyTable
3202 which is equivalent to
3205 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3206 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3209 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3210 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3211 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3214 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3216 This command may only be used inside a macro definition. It declares a
3217 list of identifiers as local to the macro expansion.
3219 A problem when using macros are labels: Since they don't change their name,
3220 you get a "duplicate symbol" error if the macro is expanded the second time.
3221 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3222 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3225 Some other assemblers start a new lexical block inside a macro expansion.
3226 This has some drawbacks however, since that will not allow <em/any/ symbol
3227 to be visible outside a macro, a feature that is sometimes useful. The
3228 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3229 to address the problem.
3231 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3235 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3237 Defines the character that start "cheap" local labels. You may use one
3238 of '@' and '?' as start character. The default is '@'.
3240 Cheap local labels are labels that are visible only between two non
3241 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3242 using explicit lexical nesting.
3249 Clear: lda #$00 ; Global label
3250 ?Loop: sta Mem,y ; Local label
3254 Sub: ... ; New global label
3255 bne ?Loop ; ERROR: Unknown identifier!
3259 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3261 Insert a predefined macro package. The command is followed by an
3262 identifier specifying the macro package to insert. Available macro
3266 atari Defines the scrcode macro.
3267 cbm Defines the scrcode macro.
3268 cpu Defines constants for the .CPU variable.
3269 generic Defines generic macros like add and sub.
3270 longbranch Defines conditional long jump macros.
3273 Including a macro package twice, or including a macro package that
3274 redefines already existing macros will lead to an error.
3279 .macpack longbranch ; Include macro package
3281 cmp #$20 ; Set condition codes
3282 jne Label ; Jump long on condition
3285 Macro packages are explained in more detail in section <ref
3286 id="macropackages" name="Macro packages">.
3289 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3291 Start a classic macro definition. The command is followed by an identifier
3292 (the macro name) and optionally by a comma separated list of identifiers
3293 that are macro parameters. A macro definition is terminated by <tt><ref
3294 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3299 .macro ldax arg ; Define macro ldax
3304 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3305 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3306 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3308 See also section <ref id="macros" name="Macros">.
3311 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3313 Start a section of absolute code. The command is followed by a constant
3314 expression that gives the new PC counter location for which the code is
3315 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3318 By default, absolute/relocatable mode is global (valid even when switching
3319 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3320 it can be made segment local.
3322 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3323 code at a specific address is the job of the linker, not the assembler, so
3324 there is usually no reason to assemble code to a specific address.
3329 .org $7FF ; Emit code starting at $7FF
3333 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3335 Output a string to the console without producing an error. This command
3336 is similar to <tt/.ERROR/, however, it does not force an assembler error
3337 that prevents the creation of an object file.
3342 .out "This code was written by the codebuster(tm)"
3345 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3346 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3347 <tt><ref id=".WARNING" name=".WARNING"></tt>
3350 <sect1><tt>.P02</tt><label id=".P02"><p>
3352 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3353 instructions. This is the default if not overridden by the
3354 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3356 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3357 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3360 <sect1><tt>.P816</tt><label id=".P816"><p>
3362 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3363 6502 instruction sets.
3365 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3366 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3369 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3371 Set the page length for the listing. Must be followed by an integer
3372 constant. The value may be "unlimited", or in the range 32 to 127. The
3373 statement has no effect if no listing is generated. The default value is -1
3374 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3375 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3376 after assembly is complete, you cannot use multiple line lengths with one
3377 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3382 .pagelength 66 ; Use 66 lines per listing page
3384 .pagelength unlimited ; Unlimited page length
3388 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3390 Enable the 65C02 instructions set. This instruction set includes all
3391 6502 and 65SC02 instructions.
3393 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3394 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3397 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3399 Pop the last CPU setting from the stack, and activate it.
3401 This command will switch back to the CPU that was last pushed onto the CPU
3402 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3403 remove this entry from the stack.
3405 The assembler will print an error message if the CPU stack is empty when
3406 this command is issued.
3408 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3409 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3412 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3414 Pop the last pushed segment from the stack, and set it.
3416 This command will switch back to the segment that was last pushed onto the
3417 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3418 command, and remove this entry from the stack.
3420 The assembler will print an error message if the segment stack is empty
3421 when this command is issued.
3423 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3426 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3428 Start a nested lexical level with the given name and adds a symbol with this
3429 name to the enclosing scope. All new symbols from now on are in the local
3430 lexical level and are accessible from outside only via <ref id="scopesyntax"
3431 name="explicit scope specification">. Symbols defined outside this local
3432 level may be accessed as long as their names are not used for new symbols
3433 inside the level. Symbols names in other lexical levels do not clash, so you
3434 may use the same names for identifiers. The lexical level ends when the
3435 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3436 may be nested up to a depth of 16 (this is an artificial limit to protect
3437 against errors in the source).
3439 Note: Macro names are always in the global level and in a separate name
3440 space. There is no special reason for this, it's just that I've never
3441 had any need for local macro definitions.
3446 .proc Clear ; Define Clear subroutine, start new level
3448 L1: sta Mem,y ; L1 is local and does not cause a
3449 ; duplicate symbol error if used in other
3452 bne L1 ; Reference local symbol
3454 .endproc ; Leave lexical level
3457 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3461 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3463 Enable the 65SC02 instructions set. This instruction set includes all
3466 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3467 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3470 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3472 Push the currently active CPU onto a stack. The stack has a size of 8
3475 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3476 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3477 later, without knowledge of the current CPU setting.
3479 The assembler will print an error message if the CPU stack is already full,
3480 when this command is issued.
3482 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3483 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3486 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3488 Push the currently active segment onto a stack. The entries on the stack
3489 include the name of the segment and the segment type. The stack has a size
3492 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3493 to switch to another segment and to restore the old segment later, without
3494 even knowing the name and type of the current segment.
3496 The assembler will print an error message if the segment stack is already
3497 full, when this command is issued.
3499 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3502 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3504 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3505 name=".ORG"></tt> command.
3508 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3510 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3511 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3512 a constant expression that tells how many times the commands in the body
3513 should get repeated. Optionally, a comma and an identifier may be specified.
3514 If this identifier is found in the body of the repeat statement, it is
3515 replaced by the current repeat count (starting with zero for the first time
3516 the body is repeated).
3518 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3519 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3520 level will be used, not the one from the outer level.
3524 The following macro will emit a string that is "encrypted" in that all
3525 characters of the string are XORed by the value $55.
3529 .repeat .strlen(Arg), I
3530 .byte .strat(Arg, I) ^ $55
3535 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3538 <sect1><tt>.RES</tt><label id=".RES"><p>
3540 Reserve storage. The command is followed by one or two constant
3541 expressions. The first one is mandatory and defines, how many bytes of
3542 storage should be defined. The second, optional expression must by a
3543 constant byte value that will be used as value of the data. If there
3544 is no fill value given, the linker will use the value defined in the
3545 linker configuration file (default: zero).
3550 ; Reserve 12 bytes of memory with value $AA
3555 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3557 Switch to the RODATA segment. The name of the RODATA segment is always
3558 "RODATA", so this is a shortcut for
3564 The RODATA segment is a segment that is used by the compiler for
3565 readonly data like string constants.
3567 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3570 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3572 Start a nested lexical level with the given name. All new symbols from now
3573 on are in the local lexical level and are accessible from outside only via
3574 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3575 outside this local level may be accessed as long as their names are not used
3576 for new symbols inside the level. Symbols names in other lexical levels do
3577 not clash, so you may use the same names for identifiers. The lexical level
3578 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3579 read. Lexical levels may be nested up to a depth of 16 (this is an
3580 artificial limit to protect against errors in the source).
3582 Note: Macro names are always in the global level and in a separate name
3583 space. There is no special reason for this, it's just that I've never
3584 had any need for local macro definitions.
3589 .scope Error ; Start new scope named Error
3591 File = 1 ; File error
3592 Parse = 2 ; Parse error
3593 .endscope ; Close lexical level
3596 lda #Error::File ; Use symbol from scope Error
3599 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3603 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3605 Switch to another segment. Code and data is always emitted into a
3606 segment, that is, a named section of data. The default segment is
3607 "CODE". There may be up to 254 different segments per object file
3608 (and up to 65534 per executable). There are shortcut commands for
3609 the most common segments ("CODE", "DATA" and "BSS").
3611 The command is followed by a string containing the segment name (there are
3612 some constraints for the name - as a rule of thumb use only those segment
3613 names that would also be valid identifiers). There may also be an optional
3614 address size separated by a colon. See the section covering <tt/<ref
3615 id="address-sizes" name="address sizes">/ for more information.
3617 The default address size for a segment depends on the memory model specified
3618 on the command line. The default is "absolute", which means that you don't
3619 have to use an address size modifier in most cases.
3621 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3622 That is, the segment will reside somewhere in core memory outside the zero
3623 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3624 page and direct (short) addressing is possible for data in this segment.
3626 Beware: Only labels in a segment with the zeropage attribute are marked
3627 as reachable by short addressing. The `*' (PC counter) operator will
3628 work as in other segments and will create absolute variable values.
3630 Please note that a segment cannot have two different address sizes. A
3631 segment specified as zeropage cannot be declared as being absolute later.
3636 .segment "ROM2" ; Switch to ROM2 segment
3637 .segment "ZP2": zeropage ; New direct segment
3638 .segment "ZP2" ; Ok, will use last attribute
3639 .segment "ZP2": absolute ; Error, redecl mismatch
3642 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3643 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3644 id=".RODATA" name=".RODATA"></tt>
3647 <sect1><tt>.SET</tt><label id=".SET"><p>
3649 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3650 name="Numeric variables"> for a full description.
3653 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3655 Switch the CPU instruction set. The command is followed by a string that
3656 specifies the CPU. Possible values are those that can also be supplied to
3657 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3658 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3659 note that support for the sunplus CPU is not available in the freeware
3660 version, because the instruction set of the sunplus CPU is "proprietary
3663 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3664 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3665 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3666 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3667 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3668 <tt><ref id=".P02" name=".P02"></tt>,
3669 <tt><ref id=".P816" name=".P816"></tt>,
3670 <tt><ref id=".PC02" name=".PC02"></tt>,
3671 <tt><ref id=".PSC02" name=".PSC02"></tt>
3674 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3676 Switch on or off smart mode. The command must be followed by a '+' or '-'
3677 character to switch the option on or off respectively. The default is off
3678 (that is, the assembler doesn't try to be smart), but this default may be
3679 changed by the -s switch on the command line.
3681 In smart mode the assembler will do the following:
3684 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3685 and update the operand sizes accordingly. If the operand of such an
3686 instruction cannot be evaluated by the assembler (for example, because
3687 the operand is an imported symbol), a warning is issued. Beware: Since
3688 the assembler cannot trace the execution flow this may lead to false
3689 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3690 instructions to tell the assembler about the current settings.
3691 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3692 used within a procedure declared as <tt/far/, or if the procedure has
3693 no explicit address specification, but it is <tt/far/ because of the
3701 .smart - ; Stop being smart
3704 See: <tt><ref id=".A16" name=".A16"></tt>,
3705 <tt><ref id=".A8" name=".A8"></tt>,
3706 <tt><ref id=".I16" name=".I16"></tt>,
3707 <tt><ref id=".I8" name=".I8"></tt>
3710 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3712 Starts a struct definition. Structs are covered in a separate section named
3713 <ref id="structs" name=""Structs and unions"">.
3715 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3716 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3717 <tt><ref id=".UNION" name=".UNION"></tt>
3720 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3722 Enable the SunPlus instructions set. This command will not work in the
3723 freeware version of the assembler, because the instruction set is
3724 "proprietary and confidential".
3726 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3727 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3728 <tt><ref id=".P816" name=".P816"></tt>
3731 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3733 Allocate space for a struct or union.
3744 .tag Point ; Allocate 4 bytes
3748 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3750 Delete a define style macro definition. The command is followed by an
3751 identifier which specifies the name of the macro to delete. Macro
3752 replacement is switched of when reading the token following the command
3753 (otherwise the macro name would be replaced by its replacement list).
3755 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3756 section <ref id="macros" name="Macros">.
3759 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3761 Starts a union definition. Unions are covered in a separate section named
3762 <ref id="structs" name=""Structs and unions"">.
3764 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3765 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3766 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3769 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3771 Force an assembly warning. The assembler will output a warning message
3772 preceded by "User warning". This warning will always be output, even if
3773 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3774 command line option.
3776 This command may be used to output possible problems when assembling
3785 .warning "Forward jump in jne, cannot optimize!"
3795 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3796 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3797 <tt><ref id=".OUT" name=".OUT"></tt>
3800 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3802 Define word sized data. Must be followed by a sequence of (word ranged,
3803 but not necessarily constant) expressions.
3808 .word $0D00, $AF13, _Clear
3812 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3814 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3815 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3819 .segment "ZEROPAGE", zeropage
3822 Because of the "zeropage" attribute, labels declared in this segment are
3823 addressed using direct addressing mode if possible. You <em/must/ instruct
3824 the linker to place this segment somewhere in the address range 0..$FF
3825 otherwise you will get errors.
3827 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3831 <sect>Macros<label id="macros"><p>
3834 <sect1>Introduction<p>
3836 Macros may be thought of as "parametrized super instructions". Macros are
3837 sequences of tokens that have a name. If that name is used in the source
3838 file, the macro is "expanded", that is, it is replaced by the tokens that
3839 were specified when the macro was defined.
3842 <sect1>Macros without parameters<p>
3844 In its simplest form, a macro does not have parameters. Here's an
3848 .macro asr ; Arithmetic shift right
3849 cmp #$80 ; Put bit 7 into carry
3850 ror ; Rotate right with carry
3854 The macro above consists of two real instructions, that are inserted into
3855 the code, whenever the macro is expanded. Macro expansion is simply done
3856 by using the name, like this:
3865 <sect1>Parametrized macros<p>
3867 When using macro parameters, macros can be even more useful:
3881 When calling the macro, you may give a parameter, and each occurrence of
3882 the name "addr" in the macro definition will be replaced by the given
3901 A macro may have more than one parameter, in this case, the parameters
3902 are separated by commas. You are free to give less parameters than the
3903 macro actually takes in the definition. You may also leave intermediate
3904 parameters empty. Empty parameters are replaced by empty space (that is,
3905 they are removed when the macro is expanded). If you have a look at our
3906 macro definition above, you will see, that replacing the "addr" parameter
3907 by nothing will lead to wrong code in most lines. To help you, writing
3908 macros with a variable parameter list, there are some control commands:
3910 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3911 returns true, if there are any tokens on the remainder of the line. Since
3912 empty parameters are replaced by nothing, this may be used to test if a given
3913 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3916 Look at this example:
3919 .macro ldaxy a, x, y
3932 This macro may be called as follows:
3935 ldaxy 1, 2, 3 ; Load all three registers
3937 ldaxy 1, , 3 ; Load only a and y
3939 ldaxy , , 3 ; Load y only
3942 There's another helper command for determining, which macro parameters are
3943 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3944 replaced by the parameter count given, <em/including/ intermediate empty macro
3948 ldaxy 1 ; .PARAMCOUNT = 1
3949 ldaxy 1,,3 ; .PARAMCOUNT = 3
3950 ldaxy 1,2 ; .PARAMCOUNT = 2
3951 ldaxy 1, ; .PARAMCOUNT = 2
3952 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3955 Macro parameters may optionally be enclosed into curly braces. This allows the
3956 inclusion of tokens that would otherwise terminate the parameter (the comma in
3957 case of a macro parameter).
3960 .macro foo arg1, arg2
3964 foo ($00,x) ; Two parameters passed
3965 foo {($00,x)} ; One parameter passed
3968 In the first case, the macro is called with two parameters: '<tt/($00/'
3969 and 'x)'. The comma is not passed to the macro, since it is part of the
3970 calling sequence, not the parameters.
3972 In the second case, '($00,x)' is passed to the macro, this time
3973 including the comma.
3976 <sect1>Detecting parameter types<p>
3978 Sometimes it is nice to write a macro that acts differently depending on the
3979 type of the argument supplied. An example would be a macro that loads a 16 bit
3980 value from either an immediate operand, or from memory. The <tt/<ref
3981 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3982 functions will allow you to do exactly this:
3986 .if (.match (.left (1, {arg}), #))
3988 lda #<(.right (.tcount ({arg})-1, {arg}))
3989 ldx #>(.right (.tcount ({arg})-1, {arg}))
3991 ; assume absolute or zero page
3998 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3999 check if its argument begins with a hash mark. If so, two immediate loads are
4000 emitted, Otherwise a load from an absolute zero page memory location is
4001 assumed. Please note how the curly braces are used to enclose parameters to
4002 pseudo functions handling token lists. This is necessary, because the token
4003 lists may include commas or parens, which would be treated by the assembler
4006 The macro can be used as
4011 ldax #$1234 ; X=$12, A=$34
4013 ldax foo ; X=$56, A=$78
4017 <sect1>Recursive macros<p>
4019 Macros may be used recursively:
4022 .macro push r1, r2, r3
4031 There's also a special macro to help writing recursive macros: <tt><ref
4032 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
4036 .macro push r1, r2, r3, r4, r5, r6, r7
4038 ; First parameter is empty
4044 push r2, r3, r4, r5, r6, r7
4048 When expanding this macro, the expansion will push all given parameters
4049 until an empty one is encountered. The macro may be called like this:
4052 push $20, $21, $32 ; Push 3 ZP locations
4053 push $21 ; Push one ZP location
4057 <sect1>Local symbols inside macros<p>
4059 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4060 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4061 Have a look at the inc16 macro above. Here is it again:
4075 If you have a closer look at the code, you will notice, that it could be
4076 written more efficiently, like this:
4087 But imagine what happens, if you use this macro twice? Since the label "Skip"
4088 has the same name both times, you get a "duplicate symbol" error. Without a
4089 way to circumvent this problem, macros are not as useful, as they could be.
4090 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4091 It declares one or more symbols as local to the macro expansion. The names of
4092 local variables are replaced by a unique name in each separate macro
4093 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4097 .local Skip ; Make Skip a local symbol
4101 Skip: ; Not visible outside
4105 Another solution is of course to start a new lexical block inside the macro
4106 that hides any labels:
4120 <sect1>C style macros<p>
4122 Starting with version 2.5 of the assembler, there is a second macro type
4123 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4124 similar to the classic macro type described above, but behaviour is sometimes
4129 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4130 span more than a line. You may use line continuation (see <tt><ref
4131 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4132 more than one line for increased readability, but the macro itself
4133 may not contain an end-of-line token.
4135 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4136 the name space with classic macros, but they are detected and replaced
4137 at the scanner level. While classic macros may be used in every place,
4138 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4139 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4140 they are more versatile in some situations.
4142 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4143 parameters. While classic macros may have empty parameters, this is
4144 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4145 For this macro type, the number of actual parameters must match
4146 exactly the number of formal parameters.
4148 To make this possible, formal parameters are enclosed in braces when
4149 defining the macro. If there are no parameters, the empty braces may
4152 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4153 contain end-of-line tokens, there are things that cannot be done. They
4154 may not contain several processor instructions for example. So, while
4155 some things may be done with both macro types, each type has special
4156 usages. The types complement each other.
4160 Let's look at a few examples to make the advantages and disadvantages
4163 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4164 following <tt/.DEFINE/:
4169 foo EQU $1234 ; This is accepted now
4172 You may use the directive to define string constants used elsewhere:
4175 ; Define the version number
4176 .define VERSION "12.3a"
4182 Macros with parameters may also be useful:
4185 .define DEBUG(message) .out message
4187 DEBUG "Assembling include file #3"
4190 Note that, while formal parameters have to be placed in braces, this is
4191 not true for the actual parameters. Beware: Since the assembler cannot
4192 detect the end of one parameter, only the first token is used. If you
4193 don't like that, use classic macros instead:
4196 .macro DEBUG message
4201 (This is an example where a problem can be solved with both macro types).
4204 <sect1>Characters in macros<p>
4206 When using the <ref id="option-t" name="-t"> option, characters are translated
4207 into the target character set of the specific machine. However, this happens
4208 as late as possible. This means that strings are translated if they are part
4209 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4210 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4211 used as part of an expression.
4213 This behaviour is very intuitive outside of macros but may be confusing when
4214 doing more complex macros. If you compare characters against numeric values,
4215 be sure to take the translation into account.
4218 <sect1>Deleting macros<p>
4220 Macros can be deleted. This will not work if the macro that should be deleted
4221 is currently expanded as in the following non working example:
4225 .delmacro notworking
4228 notworking ; Will not work
4231 The commands to delete classic and define style macros differ. Classic macros
4232 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4233 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4234 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4242 .byte value ; Emit one byte with value 1
4243 mac ; Emit another byte with value 2
4248 .byte value ; Error: Unknown identifier
4249 mac ; Error: Missing ":"
4252 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4253 the name of such a macro is replaced by its replacement list on a very low
4254 level. To get the actual name, macro replacement has to be switched off when
4255 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4256 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4257 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4258 different commands increases flexibility.
4261 <sect>Macro packages<label id="macropackages"><p>
4263 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4264 macro packages may be included with just one command. Available macro packages
4268 <sect1><tt>.MACPACK generic</tt><p>
4270 This macro package defines macros that are useful in almost any program.
4271 Currently defined macros are:
4306 <sect1><tt>.MACPACK longbranch</tt><p>
4308 This macro package defines long conditional jumps. They are named like the
4309 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4310 definition for the "<tt/jeq/" macro, the other macros are built using the same
4315 .if .def(Target) .and ((*+2)-(Target) <= 127)
4324 All macros expand to a short branch, if the label is already defined (back
4325 jump) and is reachable with a short jump. Otherwise the macro expands to a
4326 conditional branch with the branch condition inverted, followed by an absolute
4327 jump to the actual branch target.
4329 The package defines the following macros:
4332 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4337 <sect1><tt>.MACPACK atari</tt><p>
4339 The atari macro package will define a macro named <tt/scrcode/. It takes a
4340 string as argument and places this string into memory translated into screen
4344 <sect1><tt>.MACPACK cbm</tt><p>
4346 The cbm macro package will define a macro named <tt/scrcode/. It takes a
4347 string as argument and places this string into memory translated into screen
4351 <sect1><tt>.MACPACK cpu</tt><p>
4353 This macro package does not define any macros but constants used to examine
4354 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4355 each supported CPU a constant similar to
4367 is defined. These constants may be used to determine the exact type of the
4368 currently enabled CPU. In addition to that, for each CPU instruction set,
4369 another constant is defined:
4381 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4382 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4383 currently enabled CPU supports a specific instruction set. For example the
4384 65C02 supports all instructions of the 65SC02 CPU, so it has the
4385 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4389 .if (.cpu .bitand CPU_ISET_65SC02)
4397 it is possible to determine if the
4403 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4404 CPUs (the latter two are upwards compatible to the 65SC02).
4408 <sect>Predefined constants<label id="predefined-constants"><p>
4410 For better orthogonality, the assembler defines similar symbols as the
4411 compiler, depending on the target system selected:
4414 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
4415 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4416 <item><tt/__ATARI__/ - Target system is <tt/atari/
4417 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4418 <item><tt/__BBC__/ - Target system is <tt/bbc/
4419 <item><tt/__C128__/ - Target system is <tt/c128/
4420 <item><tt/__C16__/ - Target system is <tt/c16/
4421 <item><tt/__C64__/ - Target system is <tt/c64/
4422 <item><tt/__CBM__/ - Target is a Commodore system
4423 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4424 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4425 <item><tt/__GEOS__/ - Target system is <tt/geos/
4426 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4427 <item><tt/__NES__/ - Target system is <tt/nes/
4428 <item><tt/__PET__/ - Target system is <tt/pet/
4429 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4430 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4431 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4435 <sect>Structs and unions<label id="structs"><p>
4437 <sect1>Structs and unions Overview<p>
4439 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4440 are to some degree comparable to their C counterparts. Both have a list of
4441 members. Each member allocates storage and may optionally have a name, which,
4442 in case of a struct, is the offset from the beginning and, in case of a union,
4446 <sect1>Declaration<p>
4448 Here is an example for a very simple struct with two members and a total size
4458 A union shares the total space between all its members, its size is the same
4459 as that of the largest member. The offset of all members relative to the union
4469 A struct or union must not necessarily have a name. If it is anonymous, no
4470 local scope is opened, the identifiers used to name the members are placed
4471 into the current scope instead.
4473 A struct may contain unnamed members and definitions of local structs. The
4474 storage allocators may contain a multiplier, as in the example below:
4479 .word 2 ; Allocate two words
4486 <sect1>The <tt/.TAG/ keyword<p>
4488 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4489 for an already defined struct or unions within another struct:
4503 Space for a struct or union may be allocated using the <ref id=".TAG"
4504 name=".TAG"> directive.
4510 Currently, members are just offsets from the start of the struct or union. To
4511 access a field of a struct, the member offset has to be added to the address
4512 of the struct itself:
4515 lda C+Circle::Radius ; Load circle radius into A
4518 This may change in a future version of the assembler.
4521 <sect1>Limitations<p>
4523 Structs and unions are currently implemented as nested symbol tables (in fact,
4524 they were a by-product of the improved scoping rules). Currently, the
4525 assembler has no idea of types. This means that the <ref id=".TAG"
4526 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4527 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4528 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4529 this structure accessible by using the '::' operator.
4533 <sect>Module constructors/destructors<label id="condes"><p>
4535 <em>Note:</em> This section applies mostly to C programs, so the explanation
4536 below uses examples from the C libraries. However, the feature may also be
4537 useful for assembler programs.
4540 <sect1>Module constructors/destructors Overview<p>
4542 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4543 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4544 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
4545 special way. The linker is able to generate tables with all functions of a
4546 specific type. Such a table will <em>only</em> include symbols from object
4547 files that are linked into a specific executable. This may be used to add
4548 initialization and cleanup code for library modules, or a table of interrupt
4551 The C heap functions are an example where module initialization code is used.
4552 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4553 variables that contain the start and the end of the heap, pointers to the free
4554 list and so on. Since the end of the heap depends on the size and start of the
4555 stack, it must be initialized at runtime. However, initializing these
4556 variables for programs that do not use the heap are a waste of time and
4559 So the central module defines a function that contains initialization code and
4560 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4561 this module is added to an executable by the linker, the initialization
4562 function will be placed into the table of constructors by the linker. The C
4563 startup code will call all constructors before <tt/main/ and all destructors
4564 after <tt/main/, so without any further work, the heap initialization code is
4565 called once the module is linked in.
4567 While it would be possible to add explicit calls to initialization functions
4568 in the startup code, the new approach has several advantages:
4572 If a module is not included, the initialization code is not linked in and not
4573 called. So you don't pay for things you don't need.
4576 Adding another library that needs initialization does not mean that the
4577 startup code has to be changed. Before we had module constructors and
4578 destructors, the startup code for all systems had to be adjusted to call the
4579 new initialization code.
4582 The feature saves memory: Each additional initialization function needs just
4583 two bytes in the table (a pointer to the function).
4588 <sect1>Calling order<p>
4590 The symbols are sorted in increasing priority order by the linker when using
4591 one of the builtin linker configurations, so the functions with lower
4592 priorities come first and are followed by those with higher priorities. The C
4593 library runtime subroutine that walks over the function tables calls the
4594 functions starting from the top of the table - which means that functions with
4595 a high priority are called first.
4597 So when using the C runtime, functions are called with high priority functions
4598 first, followed by low priority functions.
4603 When using these special symbols, please take care of the following:
4608 The linker will only generate function tables, it will not generate code to
4609 call these functions. If you're using the feature in some other than the
4610 existing C environments, you have to write code to call all functions in a
4611 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4612 in the C runtime for an example on how to do this.
4615 The linker will only add addresses of functions that are in modules linked to
4616 the executable. This means that you have to be careful where to place the
4617 condes functions. If initialization or an irq handler is needed for a group of
4618 functions, be sure to place the function into a module that is linked in
4619 regardless of which function is called by the user.
4622 The linker will generate the tables only when requested to do so by the
4623 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4624 be requested separately.
4627 Constructors and destructors may have priorities. These priorities determine
4628 the order of the functions in the table. If your initialization or cleanup code
4629 does depend on other initialization or cleanup code, you have to choose the
4630 priority for the functions accordingly.
4633 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4634 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4635 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4636 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4637 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4638 (interruptor). The linker generates a separate table for each type on request.
4643 <sect>Porting sources from other assemblers<p>
4645 Sometimes it is necessary to port code written for older assemblers to ca65.
4646 In some cases, this can be done without any changes to the source code by
4647 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4648 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4651 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4652 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4653 done by the linker. Most other assemblers generate absolute code, placement is
4654 done within the assembler and there is no external linker.
4656 In general it is not a good idea to write new code using the emulation
4657 features of the assembler, but there may be situations where even this rule is
4662 You need to use some of the ca65 emulation features to simulate the behaviour
4663 of such simple assemblers.
4666 <item>Prepare your sourcecode like this:
4669 ; if you want TASS style labels without colons
4670 .feature labels_without_colons
4672 ; if you want TASS style character constants
4673 ; ("a" instead of the default 'a')
4674 .feature loose_char_term
4676 .word *+2 ; the cbm load address
4681 notice that the two emulation features are mostly useful for porting
4682 sources originally written in/for TASS, they are not needed for the
4683 actual "simple assembler operation" and are not recommended if you are
4684 writing new code from scratch.
4686 <item>Replace all program counter assignments (which are not possible in ca65
4687 by default, and the respective emulation feature works different from what
4688 you'd expect) by another way to skip to memory locations, for example the
4689 <tt><ref id=".RES" name=".RES"></tt> directive.
4693 .res $2000-* ; reserve memory up to $2000
4696 Please note that other than the original TASS, ca65 can never move the program
4697 counter backwards - think of it as if you are assembling to disk with TASS.
4699 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4700 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4701 of <tt/.goto/, everything involving loops must be replaced by
4702 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4704 <item>To assemble code to a different address than it is executed at, use the
4705 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4706 <tt/.offs/-constructs.
4713 .reloc ; back to normal
4716 <item>Then assemble like this:
4719 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4722 Note that you need to use the actual start address minus two, since two bytes
4723 are used for the cbm load address.
4728 <sect>Bugs/Feedback<p>
4730 If you have problems using the assembler, if you find any bugs, or if
4731 you're doing something interesting with the assembler, I would be glad to
4732 hear from you. Feel free to contact me by email
4733 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4739 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4740 Bassewitz. For usage of the binaries and/or sources the following
4741 conditions do apply:
4743 This software is provided 'as-is', without any expressed or implied
4744 warranty. In no event will the authors be held liable for any damages
4745 arising from the use of this software.
4747 Permission is granted to anyone to use this software for any purpose,
4748 including commercial applications, and to alter it and redistribute it
4749 freely, subject to the following restrictions:
4752 <item> The origin of this software must not be misrepresented; you must not
4753 claim that you wrote the original software. If you use this software
4754 in a product, an acknowledgment in the product documentation would be
4755 appreciated but is not required.
4756 <item> Altered source versions must be plainly marked as such, and must not
4757 be misrepresented as being the original software.
4758 <item> This notice may not be removed or altered from any source