1 <!doctype linuxdoc system> <!-- -*- text-mode -*- -->
4 <title>ca65 Users Guide
5 <author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
6 <url url="mailto:greg.king5@verizon.net" name="Greg King">
10 ca65 is a powerful macro assembler for the 6502, 65C02, and 65816 CPUs. It is
11 used as a companion assembler for the cc65 crosscompiler, but it may also be
12 used as a standalone product.
15 <!-- Table of contents -->
18 <!-- Begin the document -->
22 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
23 compiler, originally developed by John R. Dunning. I had some problems with
24 ra65 and the copyright does not permit some things which I wanted to be
25 possible, so I decided to write a completely new assembler/linker/archiver
26 suite for the cc65 compiler. ca65 is part of this suite.
28 Some parts of the assembler (code generation and some routines for symbol
29 table handling) are taken from an older crossassembler named a816 written
30 by me a long time ago.
33 <sect1>Design criteria<p>
35 Here's a list of the design criteria, that I considered important for the
40 <item> The assembler must support macros. Macros are not essential, but they
41 make some things easier, especially when you use the assembler in the
42 backend of a compiler.
43 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
44 thinking about a 65816 backend for the C compiler, and even my old
45 a816 assembler had support for these CPUs, so this wasn't really a
47 <item> The assembler must produce relocatable code. This is necessary for the
48 compiler support, and it is more convenient.
49 <item> Conditional assembly must be supported. This is a must for bigger
50 projects written in assembler (like Elite128).
51 <item> The assembler must support segments, and it must support more than
52 three segments (this is the count, most other assemblers support).
53 Having more than one code segments helps developing code for systems
54 with a divided ROM area (like the C64).
55 <item> The linker must be able to resolve arbitrary expressions. It should
56 be able to get things like
63 <item> True lexical nesting for symbols. This is very convenient for larger
65 <item> "Cheap" local symbols without lexical nesting for those quick, late
67 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
68 introduced the concept into the object file format use by the new cc65
70 <item> The assembler will be a one pass assembler. There was no real need for
71 this decision, but I've written several multipass assemblers, and it
72 started to get boring. A one pass assembler needs much more elaborated
73 data structures, and because of that it's much more fun:-)
74 <item> Non-GPLed code that may be used in any project without restrictions or
75 fear of "GPL infecting" other code.
83 <sect1>Command line option overview<p>
85 The assembler accepts the following options:
88 ---------------------------------------------------------------------------
89 Usage: ca65 [options] file
91 -D name[=value] Define a symbol
92 -I dir Set an include directory search path
93 -U Mark unresolved symbols as import
94 -V Print the assembler version
95 -W n Set warning level n
97 -g Add debug info to object file
99 -i Ignore case of symbols
100 -l name Create a listing file if assembly was ok
101 -mm model Set the memory model
102 -o name Name the output file
104 -t sys Set the target system
105 -v Increase verbosity
108 --auto-import Mark unresolved symbols as import
109 --bin-include-dir dir Set a search path for binary includes
110 --cpu type Set cpu type
111 --create-dep name Create a make dependency file
112 --create-full-dep name Create a full make dependency file
114 --debug-info Add debug info to object file
115 --feature name Set an emulation feature
116 --help Help (this text)
117 --ignore-case Ignore case of symbols
118 --include-dir dir Set an include directory search path
119 --large-alignment Don't warn about large alignments
120 --listing name Create a listing file if assembly was ok
121 --list-bytes n Maximum number of bytes per listing line
122 --memory-model model Set the memory model
123 --pagelength n Set the page length for the listing
124 --relax-checks Relax some checks (see docs)
125 --smart Enable smart mode
126 --target sys Set the target system
127 --verbose Increase verbosity
128 --version Print the assembler version
129 ---------------------------------------------------------------------------
133 <sect1>Command line options in detail<p>
135 Here is a description of all the command line options:
139 <label id="option--bin-include-dir">
140 <tag><tt>--bin-include-dir dir</tt></tag>
142 Name a directory which is searched for binary include files. The option
143 may be used more than once to specify more than one directory to search. The
144 current directory is always searched first before considering any
145 additional directories. See also the section about <ref id="search-paths"
146 name="search paths">.
149 <label id="option--cpu">
150 <tag><tt>--cpu type</tt></tag>
152 Set the default for the CPU type. The option takes a parameter, which
155 6502, 6502X, 65SC02, 65C02, 65816, sweet16, HuC6280, 4510
158 <label id="option-create-dep">
159 <tag><tt>--create-dep name</tt></tag>
161 Tells the assembler to generate a file containing the dependency list for
162 the assembled module in makefile syntax. The output is written to a file
163 with the given name. The output does not include files passed via debug
164 information to the assembler.
167 <label id="option-create-full-dep">
168 <tag><tt>--create-full-dep name</tt></tag>
170 Tells the assembler to generate a file containing the dependency list for
171 the assembled module in makefile syntax. The output is written to a file
172 with the given name. The output does include files passed via debug
173 information to the assembler.
176 <tag><tt>-d, --debug</tt></tag>
178 Enables debug mode, something that should not be needed for mere
182 <label id="option--feature">
183 <tag><tt>--feature name</tt></tag>
185 Enable an emulation feature. This is identical as using <tt/.FEATURE/
186 in the source with two exceptions: Feature names must be lower case, and
187 each feature must be specified by using an extra <tt/--feature/ option,
188 comma separated lists are not allowed.
190 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
191 command for a list of emulation features.
194 <label id="option-g">
195 <tag><tt>-g, --debug-info</tt></tag>
197 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
198 used, the assembler will add a section to the object file that contains
199 all symbols (including local ones) together with the symbol values and
200 source file positions. The linker will put these additional symbols into
201 the VICE label file, so even local symbols can be seen in the VICE
205 <label id="option-h">
206 <tag><tt>-h, --help</tt></tag>
208 Print the short option summary shown above.
211 <label id="option-i">
212 <tag><tt>-i, --ignore-case</tt></tag>
214 This option makes the assembler case insensitive on identifiers and labels.
215 This option will override the default, but may itself be overridden by the
216 <tt><ref id=".CASE" name=".CASE"></tt> control command.
219 <label id="option-l">
220 <tag><tt>-l name, --listing name</tt></tag>
222 Generate an assembler listing with the given name. A listing file will
223 never be generated in case of assembly errors.
226 <label id="option--large-alignment">
227 <tag><tt>--large-alignment</tt></tag>
229 Disable warnings about a large combined alignment. See the discussion of the
230 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
233 <label id="option--list-bytes">
234 <tag><tt>--list-bytes n</tt></tag>
236 Set the maximum number of bytes printed in the listing for one line of
237 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
238 for more information. The value zero can be used to encode an unlimited
239 number of printed bytes.
242 <label id="option-mm">
243 <tag><tt>-mm model, --memory-model model</tt></tag>
245 Define the default memory model. Possible model specifiers are near, far and
249 <label id="option-o">
250 <tag><tt>-o name</tt></tag>
252 The default output name is the name of the input file with the extension
253 replaced by ".o". If you don't like that, you may give another name with
254 the -o option. The output file will be placed in the same directory as
255 the source file, or, if -o is given, the full path in this name is used.
258 <label id="option--pagelength">
259 <tag><tt>--pagelength n</tt></tag>
261 sets the length of a listing page in lines. See the <tt><ref
262 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
265 <label id="option--relax-checks">
266 <tag><tt>--relax-checks</tt></tag>
268 Relax some checks done by the assembler. This will allow code that is an
269 error in most cases and flagged as such by the assembler, but can be valid
270 in special situations.
274 <item>Short branches between two different segments.
275 <item>Byte sized address loads where the address is not a zeropage address.
279 <label id="option-s">
280 <tag><tt>-s, --smart-mode</tt></tag>
282 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
283 pseudo instruction) the assembler will track usage of the <tt/REP/ and
284 <tt/SEP/ instructions in 65816 mode and update the operand sizes
285 accordingly. If the operand of such an instruction cannot be evaluated by
286 the assembler (for example, because the operand is an imported symbol), a
289 Beware: Since the assembler cannot trace the execution flow this may
290 lead to false results in some cases. If in doubt, use the .ixx and .axx
291 instructions to tell the assembler about the current settings. Smart
292 mode is off by default.
295 <label id="option-t">
296 <tag><tt>-t sys, --target sys</tt></tag>
298 Set the target system. This will enable translation of character strings and
299 character constants into the character set of the target platform. The
300 default for the target system is "none", which means that no translation
301 will take place. The assembler supports the same target systems as the
302 compiler, see there for a list.
304 Depending on the target, the default CPU type is also set. This can be
305 overriden by using the <tt/<ref id="option--cpu" name="--cpu">/ option.
308 <label id="option-v">
309 <tag><tt>-v, --verbose</tt></tag>
311 Increase the assembler verbosity. Usually only needed for debugging
312 purposes. You may use this option more than one time for even more
316 <label id="option-D">
317 <tag><tt>-D</tt></tag>
319 This option allows you to define symbols on the command line. Without a
320 value, the symbol is defined with the value zero. When giving a value,
321 you may use the '$' prefix for hexadecimal symbols. Please note
322 that for some operating systems, '$' has a special meaning, so
323 you may have to quote the expression.
326 <label id="option-I">
327 <tag><tt>-I dir, --include-dir dir</tt></tag>
329 Name a directory which is searched for include files. The option may be
330 used more than once to specify more than one directory to search. The
331 current directory is always searched first before considering any
332 additional directories. See also the section about <ref id="search-paths"
333 name="search paths">.
336 <label id="option-U">
337 <tag><tt>-U, --auto-import</tt></tag>
339 Mark symbols that are not defined in the sources as imported symbols. This
340 should be used with care since it delays error messages about typos and such
341 until the linker is run. The compiler uses the equivalent of this switch
342 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
343 symbols for the runtime library. However, the compiler is supposed to
344 generate code that runs through the assembler without problems, something
345 which is not always true for assembler programmers.
348 <label id="option-V">
349 <tag><tt>-V, --version</tt></tag>
351 Print the version number of the assembler. If you send any suggestions
352 or bugfixes, please include the version number.
355 <label id="option-W">
356 <tag><tt>-Wn</tt></tag>
358 Set the warning level for the assembler. Using -W2 the assembler will
359 even warn about such things like unused imported symbols. The default
360 warning level is 1, and it would probably be silly to set it to
368 <sect>Search paths<label id="search-paths"><p>
370 Normal include files are searched in the following places:
373 <item>The current file's directory.
374 <item>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
376 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
377 <item>A subdirectory named <tt/asminc/ of the directory defined in the
378 environment variable <tt/CC65_HOME/, if it is defined.
379 <item>An optionally compiled-in directory.
382 Binary include files are searched in the following places:
385 <item>The current file's directory.
386 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
387 name="--bin-include-dir">/ option on the command line.
392 <sect>Input format<p>
394 <sect1>Assembler syntax<p>
396 The assembler accepts the standard 6502/65816 assembler syntax. One line may
397 contain a label (which is identified by a colon), and, in addition to the
398 label, an assembler mnemonic, a macro, or a control command (see section <ref
399 id="control-commands" name="Control Commands"> for supported control
400 commands). Alternatively, the line may contain a symbol definition using
401 the '=' token. Everything after a semicolon is handled as a comment (that is,
404 Here are some examples for valid input lines:
407 Label: ; A label and a comment
408 lda #$20 ; A 6502 instruction plus comment
409 L1: ldx #$20 ; Same with label
410 L2: .byte "Hello world" ; Label plus control command
411 mymac $20 ; Macro expansion
412 MySym = 3*L1 ; Symbol definition
413 MaSym = Label ; Another symbol
416 The assembler accepts
419 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
420 <tt><ref id=".P02" name=".P02"></tt> command was given).
421 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
422 <ref id="6502X-mode" name="6502X mode">.
423 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
424 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
425 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
426 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
427 <item>all valid 65618 mnemonics when in 65816 mode (after the
428 <tt><ref id=".P816" name=".P816"></tt> command was given).
434 In 65816 mode, several aliases are accepted, in addition to the official
438 <item><tt>CPA</tt> is an alias for <tt>CMP</tt>
439 <item><tt>DEA</tt> is an alias for <tt>DEC A</tt>
440 <item><tt>INA</tt> is an alias for <tt>INC A</tt>
441 <item><tt>SWA</tt> is an alias for <tt>XBA</tt>
442 <item><tt>TAD</tt> is an alias for <tt>TCD</tt>
443 <item><tt>TAS</tt> is an alias for <tt>TCS</tt>
444 <item><tt>TDA</tt> is an alias for <tt>TDC</tt>
445 <item><tt>TSA</tt> is an alias for <tt>TSC</tt>
449 <sect1>6502X mode<label id="6502X-mode"><p>
451 6502X mode is an extension to the normal 6502 mode. In this mode, several
452 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
453 these instructions are illegal, there are no official mnemonics for them. The
454 unofficial ones are taken from <url
455 url="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
456 ones marked as "stable" are supported. The following table uses information
457 from the mentioned web page, for more information, see there.
460 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
461 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
462 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
463 <item><tt>AXS: X:=A and X-#{imm};</tt>
464 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
465 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
466 <item><tt>LAS: A,X,S:={adr} and S;</tt>
467 <item><tt>LAX: A,X:={adr};</tt>
468 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
469 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
470 <item><tt>SAX: {adr}:=A and X;</tt>
471 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
472 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
478 The 4510 is a microcontroller that is the core of the Commodore C65 aka C64DX.
479 It contains among other functions a slightly modified 65CE02 CPU, to allow
480 address mapping for 20 bits of address space (1 megabyte addressable area).
481 As compared to the description of the CPU in the System Specification of the
482 Commodore C65 aka C64DX prototypes ca65 uses these changes:
484 <item><tt>LDA (d,SP),Y</tt> may also be written as <tt>LDA (d,S),Y</tt>
485 (matching the 65816 notataion).
486 <item>All branch instruction allow now 16 bit offsets. To use a 16 bit
487 branch you have to prefix these with an "L" (e.g. "<tt>LBNE</tt>" instead of
488 "<tt>BNE</tt>"). This might change at a later implementation of the assember.
490 For more information about the Commodore C65/C64DX and the 4510 CPU, see
491 <url url="http://www.zimmers.net/anonftp/pub/cbm/c65/c65manualupdated.txt.gz">.
494 <sect1>sweet16 mode<label id="sweet16-mode"><p>
496 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
497 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
498 generate code for this pseudo CPU when switched into sweet16 mode. The
499 following is special in sweet16 mode:
503 <item>The '@' character denotes indirect addressing and is no longer available
504 for cheap local labels. If you need cheap local labels, you will have to
505 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
506 name=".LOCALCHAR">/ command.
508 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
509 these identifiers are reserved words.
513 Please note that the assembler does neither supply the interpreter needed for
514 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
515 nor does it call the interpreter. All this must be done by your program. Apple
516 ][ programmers do probably know how to use sweet16 mode.
518 For more information about SWEET 16, see
519 <url url="http://www.6502.org/source/interpreters/sweet16.htm">.
522 <sect1>Number format<p>
524 For literal values, the assembler accepts the widely used number formats: A
525 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
526 denotes a binary value, and a bare number is interpreted as a decimal. There
527 are currently no octal values and no floats.
530 <sect1>Conditional assembly<p>
532 Please note that when using the conditional directives (<tt/.IF/ and friends),
533 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
534 that are not assembled. The reason for this behaviour is that the assembler
535 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
536 conversion of the input stream into tokens still takes place. As a consequence
537 conditional assembly directives may <bf/not/ be used to prevent normal text
538 (used as a comment or similar) from being assembled. <p>
544 <sect1>Expression evaluation<p>
546 All expressions are evaluated with (at least) 32 bit precision. An
547 expression may contain constant values and any combination of internal and
548 external symbols. Expressions that cannot be evaluated at assembly time
549 are stored inside the object file for evaluation by the linker.
550 Expressions referencing imported symbols must always be evaluated by the
554 <sect1>Size of an expression result<p>
556 Sometimes, the assembler must know about the size of the value that is the
557 result of an expression. This is usually the case, if a decision has to be
558 made, to generate a zero page or an absolute memory references. In this
559 case, the assembler has to make some assumptions about the result of an
563 <item> If the result of an expression is constant, the actual value is
564 checked to see if it's a byte sized expression or not.
565 <item> If the expression is explicitly casted to a byte sized expression by
566 one of the '>', '<' or '^' operators, it is a byte expression.
567 <item> If this is not the case, and the expression contains a symbol,
568 explicitly declared as zero page symbol (by one of the .importzp or
569 .exportzp instructions), then the whole expression is assumed to be
571 <item> If the expression contains symbols that are not defined, and these
572 symbols are local symbols, the enclosing scopes are searched for a
573 symbol with the same name. If one exists and this symbol is defined,
574 its attributes are used to determine the result size.
575 <item> In all other cases the expression is assumed to be word sized.
578 Note: If the assembler is not able to evaluate the expression at assembly
579 time, the linker will evaluate it and check for range errors as soon as
583 <sect1>Boolean expressions<p>
585 In the context of a boolean expression, any non zero value is evaluated as
586 true, any other value to false. The result of a boolean expression is 1 if
587 it's true, and zero if it's false. There are boolean operators with extreme
588 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
589 operators are shortcut operators. That is, if the result of the expression is
590 already known, after evaluating the left hand side, the right hand side is
594 <sect1>Constant expressions<p>
596 Sometimes an expression must evaluate to a constant without looking at any
597 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
598 that decides if parts of the code are assembled or not. An expression used in
599 the <tt/.IF/ command cannot reference a symbol defined later, because the
600 decision about the <tt/.IF/ must be made at the point when it is read. If the
601 expression used in such a context contains only constant numerical values,
602 there is no problem. When unresolvable symbols are involved it may get harder
603 for the assembler to determine if the expression is actually constant, and it
604 is even possible to create expressions that aren't recognized as constant.
605 Simplifying the expressions will often help.
607 In cases where the result of the expression is not needed immediately, the
608 assembler will delay evaluation until all input is read, at which point all
609 symbols are known. So using arbitrary complex constant expressions is no
610 problem in most cases.
614 <sect1>Available operators<label id="operators"><p>
618 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
619 | Built-in string functions| 0@
621 | Built-in pseudo-variables| 1@
622 | Built-in pseudo-functions| 1@
623 +| Unary positive| 1@
624 -| Unary negative| 1@
626 .BITNOT| Unary bitwise not| 1@
628 .LOBYTE| Unary low-byte operator| 1@
630 .HIBYTE| Unary high-byte operator| 1@
632 .BANKBYTE| Unary bank-byte operator| 1@
634 *| Multiplication| 2@
636 .MOD| Modulo operator| 2@
638 .BITAND| Bitwise and| 2@
640 .BITXOR| Binary bitwise xor| 2@
642 .SHL| Shift-left operator| 2@
644 .SHR| Shift-right operator| 2@
646 +| Binary addition| 3@
647 -| Binary subtraction| 3@
649 .BITOR| Bitwise or| 3@
651 = | Compare operator (equal)| 4@
652 <>| Compare operator (not equal)| 4@
653 <| Compare operator (less)| 4@
654 >| Compare operator (greater)| 4@
655 <=| Compare operator (less or equal)| 4@
656 >=| Compare operator (greater or equal)| 4@
659 .AND| Boolean and| 5@
660 .XOR| Boolean xor| 5@
662 ||<newline>
666 .NOT| Boolean not| 7@<hline>
668 <caption>Available operators, sorted by precedence
671 To force a specific order of evaluation, parentheses may be used, as usual.
675 <sect>Symbols and labels<p>
677 A symbol or label is an identifier that starts with a letter and is followed
678 by letters and digits. Depending on some features enabled (see
679 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
680 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
681 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
682 other characters may be present. Use of identifiers consisting of a single
683 character will not work in all cases, because some of these identifiers are
684 reserved keywords (for example "A" is not a valid identifier for a label,
685 because it is the keyword for the accumulator).
687 The assembler allows you to use symbols instead of naked values to make
688 the source more readable. There are a lot of different ways to define and
689 use symbols and labels, giving a lot of flexibility.
691 <sect1>Numeric constants<p>
693 Numeric constants are defined using the equal sign or the label assignment
694 operator. After doing
700 may use the symbol "two" in every place where a number is expected, and it is
701 evaluated to the value 2 in this context. The label assignment operator is
702 almost identical, but causes the symbol to be marked as a label, so it may be
703 handled differently in a debugger:
709 The right side can of course be an expression:
716 <label id="variables">
717 <sect1>Numeric variables<p>
719 Within macros and other control structures (<tt><ref id=".REPEAT"
720 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
721 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
722 symbol that may get assigned a different value later:
726 lda #four ; Loads 4 into A
728 lda #four ; Loads 3 into A
731 Since the value of the symbol can change later, it must be possible to
732 evaluate it when used (no delayed evaluation as with normal symbols). So the
733 expression used as the value must be constant.
735 Following is an example for a macro that generates a different label each time
736 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
737 and a numeric variable named <tt>lcount</tt>.
740 .lcount .set 0 ; Initialize the counter
743 .ident (.sprintf ("L%04X", lcount)):
744 lcount .set lcount + 1
749 <sect1>Standard labels<p>
751 A label is defined by writing the name of the label at the start of the line
752 (before any instruction mnemonic, macro or pseudo directive), followed by a
753 colon. This will declare a symbol with the given name and the value of the
754 current program counter.
757 <sect1>Local labels and symbols<p>
759 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
760 create regions of code where the names of labels and symbols are local to this
761 region. They are not known outside of this region and cannot be accessed from
762 there. Such regions may be nested like PROCEDUREs in Pascal.
764 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
765 directive for more information.
768 <sect1>Cheap local labels<p>
770 Cheap local labels are defined like standard labels, but the name of the
771 label must begin with a special symbol (usually '@', but this can be
772 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
775 Cheap local labels are visible only between two non cheap labels. As soon as a
776 standard symbol is encountered (this may also be a local symbol if inside a
777 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
778 cheap local symbol goes out of scope.
780 You may use cheap local labels as an easy way to reuse common label
781 names like "Loop". Here is an example:
784 Clear: lda #$00 ; Global label
786 @Loop: sta Mem,y ; Local label
790 Sub: ... ; New global label
791 bne @Loop ; ERROR: Unknown identifier!
794 <sect1>Unnamed labels<p>
796 If you really want to write messy code, there are also unnamed labels. These
797 labels do not have a name (you guessed that already, didn't you?). A colon is
798 used to mark the absence of the name.
800 Unnamed labels may be accessed by using the colon plus several minus or plus
801 characters as a label designator. Using the '-' characters will create a back
802 reference (use the n'th label backwards), using '+' will create a forward
803 reference (use the n'th label in forward direction). An example will help to
826 As you can see from the example, unnamed labels will make even short
827 sections of code hard to understand, because you have to count labels
828 to find branch targets (this is the reason why I for my part do
829 prefer the "cheap" local labels). Nevertheless, unnamed labels are
830 convenient in some situations, so it's your decision.
832 <em/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
833 unnamed ones, so scopes don't have an effect on unnamed labels.
837 <sect1>Using macros to define labels and constants<p>
839 While there are drawbacks with this approach, it may be handy in a few rare
840 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
841 to define symbols or constants that may be used elsewhere. One of the
842 advantages is that you can use it to define string constants (this is not
843 possible with the other symbol types).
845 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
846 so the names do not adhere to scoping, diagnostics may be misleading, there
847 are no symbols to look up in the map file, and there is no debug info.
848 Especially the first problem in the list can lead to very nasty programming
849 errors. Because of these problems, the general advice is, <bf/NOT/ do use
850 <tt/.DEFINE/ if you don't have to.
856 .DEFINE version "SOS V2.3"
858 four = two * two ; Ok
861 .PROC ; Start local scope
862 two = 3 ; Will give "2 = 3" - invalid!
867 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
869 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
870 id="option-g" name="-g"> is given on the command line), global, local and
871 cheap local labels are written to the object file and will be available in the
872 symbol file via the linker. Unnamed labels are not written to the object file,
873 because they don't have a name which would allow to access them.
877 <sect>Scopes<label id="scopes"><p>
879 ca65 implements several sorts of scopes for symbols.
881 <sect1>Global scope<p>
883 All (non cheap local) symbols that are declared outside of any nested scopes
887 <sect1>Cheap locals<p>
889 A special scope is the scope for cheap local symbols. It lasts from one non
890 local symbol to the next one, without any provisions made by the programmer.
891 All other scopes differ in usage but use the same concept internally.
894 <sect1>Generic nested scopes<p>
896 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
897 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
898 The scope can have a name, in which case it is accessible from the outside by
899 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
900 have a name, all symbols created within the scope are local to the scope, and
901 aren't accessible from the outside.
903 A nested scope can access symbols from the local or from enclosing scopes by
904 name without using explicit scope names. In some cases there may be
905 ambiguities, for example if there is a reference to a local symbol that is not
906 yet defined, but a symbol with the same name exists in outer scopes:
918 In the example above, the <tt/lda/ instruction will load the value 3 into the
919 accumulator, because <tt/foo/ is redefined in the scope. However:
931 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
932 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
933 absolute mode is used instead. In fact, the assembler will not use absolute
934 mode by default, but it will search through the enclosing scopes for a symbol
935 with the given name. If one is found, the address size of this symbol is used.
936 This may lead to errors:
948 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
949 instruction, it will search for an already defined symbol <tt/foo/. It will
950 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
951 zeropage symbol. So the assembler will use zeropage addressing mode. If
952 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
953 the address in the <tt/lda/ instruction already translated, but since the new
954 value needs absolute addressing mode, this fails, and an error message "Range
957 Of course the most simple solution for the problem is to move the definition
958 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
959 rare cases when this cannot be done. In these cases, you can use one of the
960 address size override operators:
972 This will cause the <tt/lda/ instruction to be translated using absolute
973 addressing mode, which means changing the symbol reference later does not
977 <sect1>Nested procedures<p>
979 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
980 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
981 name, and a it will introduce a symbol with this name in the enclosing scope.
990 is actually the same as
999 This is the reason why a procedure must have a name. If you want a scope
1000 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
1002 <em/Note:/ As you can see from the example above, scopes and symbols live in
1003 different namespaces. There can be a symbol named <tt/foo/ and a scope named
1004 <tt/foo/ without any conflicts (but see the section titled <ref
1005 id="scopesearch" name=""Scope search order"">).
1008 <sect1>Structs, unions and enums<p>
1010 Structs, unions and enums are explained in a <ref id="structs" name="separate
1011 section">, I do only cover them here, because if they are declared with a
1012 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
1013 name=".SCOPE">/. However, when no name is specified, the behaviour is
1014 different: In this case, no new scope will be opened, symbols declared within
1015 a struct, union, or enum declaration will then be added to the enclosing scope
1019 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1021 Accessing symbols from other scopes is possible by using an explicit scope
1022 specification, provided that the scope where the symbol lives in has a name.
1023 The namespace token (<tt/::/) is used to access other scopes:
1031 lda foo::bar ; Access foo in scope bar
1034 The only way to deny access to a scope from the outside is to declare a scope
1035 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1037 A special syntax is used to specify the global scope: If a symbol or scope is
1038 preceded by the namespace token, the global scope is searched:
1045 lda #::bar ; Access the global bar (which is 3)
1050 <sect1>Scope search order<label id="scopesearch"><p>
1052 The assembler searches for a scope in a similar way as for a symbol. First, it
1053 looks in the current scope, and then it walks up the enclosing scopes until
1056 However, one important thing to note when using explicit scope syntax is, that
1057 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1058 used without a preceding definition. This means that in the following
1067 lda #foo::bar ; Will load 3, not 2!
1074 the reference to the scope <tt/foo/ will use the global scope, and not the
1075 local one, because the local one is not visible at the point where it is
1078 Things get more complex if a complete chain of scopes is specified:
1089 lda #outer::inner::bar ; 1
1101 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1102 assembler will first search in the local scope for a scope named <tt/outer/.
1103 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1104 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1105 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1106 this scope, the assembler looks for a symbol named <tt/bar/.
1108 Please note that once the anchor scope is found, all following scopes
1109 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1110 assembler will search the scope tree only for the first scope (if it is not
1111 anchored in the root scope). Starting from there on, there is no flexibility,
1112 so if the scope named <tt/outer/ found by the assembler does not contain a
1113 scope named <tt/inner/, this would be an error, even if such a pair does exist
1114 (one level up in global scope).
1116 Ambiguities that may be introduced by this search algorithm may be removed by
1117 anchoring the scope specification in the global scope. In the example above,
1118 if you want to access the "other" symbol <tt/bar/, you would have to write:
1129 lda #::outer::inner::bar ; 2
1142 <sect>Address sizes and memory models<label id="address-sizes"><p>
1144 <sect1>Address sizes<p>
1146 ca65 assigns each segment and each symbol an address size. This is true, even
1147 if the symbol is not used as an address. You may also think of a value range
1148 of the symbol instead of an address size.
1150 Possible address sizes are:
1153 <item>Zeropage or direct (8 bits)
1154 <item>Absolute (16 bits)
1156 <item>Long (32 bits)
1159 Since the assembler uses default address sizes for the segments and symbols,
1160 it is usually not necessary to override the default behaviour. In cases, where
1161 it is necessary, the following keywords may be used to specify address sizes:
1164 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1165 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1166 <item>FAR for far addressing (24 bits).
1167 <item>LONG or DWORD for long addressing (32 bits).
1171 <sect1>Address sizes of segments<p>
1173 The assembler assigns an address size to each segment. Since the
1174 representation of a label within this segment is "segment start + offset",
1175 labels will inherit the address size of the segment they are declared in.
1177 The address size of a segment may be changed, by using an optional address
1178 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1179 an explanation on how this is done.
1182 <sect1>Address sizes of symbols<p>
1187 <sect1>Memory models<p>
1189 The default address size of a segment depends on the memory model used. Since
1190 labels inherit the address size from the segment they are declared in,
1191 changing the memory model is an easy way to change the address size of many
1197 <sect>Pseudo variables<label id="pseudo-variables"><p>
1199 Pseudo variables are readable in all cases, and in some special cases also
1202 <sect1><tt>*</tt><p>
1204 Reading this pseudo variable will return the program counter at the start
1205 of the current input line.
1207 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1208 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1209 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1212 <sect1><tt>.ASIZE</tt><label id=".ASIZE"><p>
1214 Reading this pseudo variable will return the current size of the
1215 Accumulator in bits.
1217 For the 65816 instruction set .ASIZE will return either 8 or 16, depending
1218 on the current size of the operand in immediate accu addressing mode.
1220 For all other CPU instruction sets, .ASIZE will always return 8.
1225 ; Reverse Subtract with Accumulator
1238 See also: <tt><ref id=".ISIZE" name=".ISIZE"></tt>
1241 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1243 Reading this pseudo variable will give a constant integer value that
1244 tells which CPU is currently enabled. It can also tell which instruction
1245 set the CPU is able to translate. The value read from the pseudo variable
1246 should be further examined by using one of the constants defined by the
1247 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1249 It may be used to replace the .IFPxx pseudo instructions or to construct
1250 even more complex expressions.
1256 .if (.cpu .bitand CPU_ISET_65816)
1268 <sect1><tt>.ISIZE</tt><label id=".ISIZE"><p>
1270 Reading this pseudo variable will return the current size of the Index
1273 For the 65816 instruction set .ISIZE will return either 8 or 16, depending
1274 on the current size of the operand in immediate index addressing mode.
1276 For all other CPU instruction sets, .ISIZE will always return 8.
1278 See also: <tt><ref id=".ASIZE" name=".ASIZE"></tt>
1281 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1283 This builtin pseudo variable is only available in macros. It is replaced by
1284 the actual number of parameters that were given in the macro invocation.
1289 .macro foo arg1, arg2, arg3
1290 .if .paramcount <> 3
1291 .error "Too few parameters for macro foo"
1297 See section <ref id="macros" name="Macros">.
1300 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1302 Reading this pseudo variable will give a constant integer value that
1303 represents the current time in POSIX standard (as seconds since the
1306 It may be used to encode the time of translation somewhere in the created
1312 .dword .time ; Place time here
1316 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1318 Reading this pseudo variable will give the assembler version according to
1319 the following formula:
1321 VER_MAJOR*$100 + VER_MINOR*$10
1323 It may be used to encode the assembler version or check the assembler for
1324 special features not available with older versions.
1328 Version 2.14 of the assembler will return $2E0 as numerical constant when
1329 reading the pseudo variable <tt/.VERSION/.
1333 <sect>Pseudo functions<label id="pseudo-functions"><p>
1335 Pseudo functions expect their arguments in parenthesis, and they have a result,
1336 either a string or an expression.
1339 <sect1><tt>.ADDRSIZE</tt><label id=".ADDRSIZE"><p>
1341 The <tt/.ADDRSIZE/ function is used to return the interal address size
1342 associated with a symbol. This can be helpful in macros when knowing the address
1343 size of symbol can help with custom instructions.
1349 .if .ADDRSIZE(foo) = 1
1350 ;do custom command based on zeropage addressing:
1352 .elseif .ADDRSIZE(foo) = 2
1353 ;do custom command based on absolute addressing:
1356 .elseif .ADDRSIZE(foo) = 0
1357 ; no address size defined for this symbol:
1358 .out .sprintf("Error, address size unknown for symbol %s", .string(foo))
1363 This command is new and must be enabled with the <tt/.FEATURE addrsize/ command.
1365 See: <tt><ref id=".FEATURE" name=".FEATURE"></tt>
1368 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1370 The <tt/.BANK/ function is used to support systems with banked memory. The
1371 argument is an expression with exactly one segment reference - usually a
1372 label. The function result is the value of the <tt/bank/ attribute assigned
1373 to the run memory area of the segment. Please see the linker documentation
1374 for more information about memory areas and their attributes.
1376 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1377 containing specific data is available.
1379 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1380 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1381 name=".LOBYTE"></tt> or similar functions to address just part of it.
1383 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1384 an expression containing <tt/.BANK/ can never be used where a constant known
1385 result is expected (for example with <tt/.RES/).
1402 .byte <.BANK (banked_func_1)
1405 .byte <.BANK (banked_func_2)
1411 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1413 The function returns the bank byte (that is, bits 16-23) of its argument.
1414 It works identical to the '^' operator.
1416 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1417 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1420 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1422 Builtin function. The function evaluates its argument in braces and yields
1423 "false" if the argument is non blank (there is an argument), and "true" if
1424 there is no argument. The token list that makes up the function argument
1425 may optionally be enclosed in curly braces. This allows the inclusion of
1426 tokens that would otherwise terminate the list (the closing right
1427 parenthesis). The curly braces are not considered part of the list, a list
1428 just consisting of curly braces is considered to be empty.
1430 As an example, the <tt/.IFBLANK/ statement may be replaced by
1438 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1440 Builtin string function. The function allows to concatenate a list of string
1441 constants separated by commas. The result is a string constant that is the
1442 concatenation of all arguments. This function is most useful in macros and
1443 when used together with the <tt/.STRING/ builtin function. The function may
1444 be used in any case where a string constant is expected.
1449 .include .concat ("myheader", ".", "inc")
1452 This is the same as the command
1455 .include "myheader.inc"
1459 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1461 Builtin function. The function evaluates its argument in braces and
1462 yields "true" if the argument is a constant expression (that is, an
1463 expression that yields a constant value at assembly time) and "false"
1464 otherwise. As an example, the .IFCONST statement may be replaced by
1471 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1473 The function returns the high byte (that is, bits 8-15) of its argument.
1474 It works identical to the '>' operator.
1476 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1477 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1480 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1482 The function returns the high word (that is, bits 16-31) of its argument.
1484 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1487 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1489 The function expects a string as its argument, and converts this argument
1490 into an identifier. If the string starts with the current <tt/<ref
1491 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1492 identifier, otherwise it will be converted into a normal identifier.
1497 .macro makelabel arg1, arg2
1498 .ident (.concat (arg1, arg2)):
1501 makelabel "foo", "bar"
1503 .word foobar ; Valid label
1507 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1509 Builtin function. Extracts the left part of a given token list.
1514 .LEFT (<int expr>, <token list>)
1517 The first integer expression gives the number of tokens to extract from
1518 the token list. The second argument is the token list itself. The token
1519 list may optionally be enclosed into curly braces. This allows the
1520 inclusion of tokens that would otherwise terminate the list (the closing
1521 right paren in the given case).
1525 To check in a macro if the given argument has a '#' as first token
1526 (immediate addressing mode), use something like this:
1531 .if (.match (.left (1, {arg}), #))
1533 ; ldax called with immediate operand
1541 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1542 name=".RIGHT"></tt> builtin functions.
1545 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1547 The function returns the low byte (that is, bits 0-7) of its argument.
1548 It works identical to the '<' operator.
1550 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1551 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1554 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1556 The function returns the low word (that is, bits 0-15) of its argument.
1558 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1561 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1563 Builtin function. Matches two token lists against each other. This is
1564 most useful within macros, since macros are not stored as strings, but
1570 .MATCH(<token list #1>, <token list #2>)
1573 Both token list may contain arbitrary tokens with the exception of the
1574 terminator token (comma resp. right parenthesis) and
1581 The token lists may optionally be enclosed into curly braces. This allows
1582 the inclusion of tokens that would otherwise terminate the list (the closing
1583 right paren in the given case). Often a macro parameter is used for any of
1586 Please note that the function does only compare tokens, not token
1587 attributes. So any number is equal to any other number, regardless of the
1588 actual value. The same is true for strings. If you need to compare tokens
1589 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1590 name=".XMATCH"></tt> function.
1594 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1595 while honoring the sign bit. The builtin processor instructions will allow
1596 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1597 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1598 to check for this and print and error for invalid calls.
1603 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1604 .error "Syntax error"
1607 cmp #$80 ; Bit 7 into carry
1608 lsr a ; Shift carry into bit 7
1613 The macro will only accept no arguments, or one argument that must be the
1614 reserved keyword "A".
1616 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1619 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1621 Builtin function. The result is the larger of two values.
1626 .MAX (<value #1>, <value #2>)
1632 ; Reserve space for the larger of two data blocks
1633 savearea: .max (.sizeof (foo), .sizeof (bar))
1636 See: <tt><ref id=".MIN" name=".MIN"></tt>
1639 <sect1><tt>.MID</tt><label id=".MID"><p>
1641 Builtin function. Takes a starting index, a count and a token list as
1642 arguments. Will return part of the token list.
1647 .MID (<int expr>, <int expr>, <token list>)
1650 The first integer expression gives the starting token in the list (the first
1651 token has index 0). The second integer expression gives the number of tokens
1652 to extract from the token list. The third argument is the token list itself.
1653 The token list may optionally be enclosed into curly braces. This allows the
1654 inclusion of tokens that would otherwise terminate the list (the closing
1655 right paren in the given case).
1659 To check in a macro if the given argument has a '<tt/#/' as first token
1660 (immediate addressing mode), use something like this:
1665 .if (.match (.mid (0, 1, {arg}), #))
1667 ; ldax called with immediate operand
1675 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1676 name=".RIGHT"></tt> builtin functions.
1679 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1681 Builtin function. The result is the smaller of two values.
1686 .MIN (<value #1>, <value #2>)
1692 ; Reserve space for some data, but 256 bytes minimum
1693 savearea: .min (.sizeof (foo), 256)
1696 See: <tt><ref id=".MAX" name=".MAX"></tt>
1699 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1701 Builtin function. The function expects an identifier as argument in braces.
1702 The argument is evaluated, and the function yields "true" if the identifier
1703 is a symbol that has already been referenced somewhere in the source file up
1704 to the current position. Otherwise the function yields false. As an example,
1705 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1711 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1714 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1716 Builtin function. Extracts the right part of a given token list.
1721 .RIGHT (<int expr>, <token list>)
1724 The first integer expression gives the number of tokens to extract from the
1725 token list. The second argument is the token list itself. The token list
1726 may optionally be enclosed into curly braces. This allows the inclusion of
1727 tokens that would otherwise terminate the list (the closing right paren in
1730 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1731 name=".MID"></tt> builtin functions.
1734 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1736 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1737 argument can be a struct/union, a struct member, a procedure, or a label. In
1738 case of a procedure or label, its size is defined by the amount of data
1739 placed in the segment where the label is relative to. If a line of code
1740 switches segments (for example in a macro) data placed in other segments
1741 does not count for the size.
1743 Please note that a symbol or scope must exist, before it is used together with
1744 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1745 A scope has preference over a symbol with the same name, so if the last part
1746 of a name represents both, a scope and a symbol, the scope is chosen over the
1749 After the following code:
1752 .struct Point ; Struct size = 4
1757 P: .tag Point ; Declare a point
1758 @P: .tag Point ; Declare another point
1770 .data ; Segment switch!!!
1776 <tag><tt/.sizeof(Point)/</tag>
1777 will have the value 4, because this is the size of struct <tt/Point/.
1779 <tag><tt/.sizeof(Point::xcoord)/</tag>
1780 will have the value 2, because this is the size of the member <tt/xcoord/
1781 in struct <tt/Point/.
1783 <tag><tt/.sizeof(P)/</tag>
1784 will have the value 4, this is the size of the data declared on the same
1785 source line as the label <tt/P/, which is in the same segment that <tt/P/
1788 <tag><tt/.sizeof(@P)/</tag>
1789 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1790 does also work for cheap local symbols.
1792 <tag><tt/.sizeof(Code)/</tag>
1793 will have the value 3, since this is amount of data emitted into the code
1794 segment, the segment that was active when <tt/Code/ was entered. Note that
1795 this value includes the amount of data emitted in child scopes (in this
1796 case <tt/Code::Inner/).
1798 <tag><tt/.sizeof(Code::Inner)/</tag>
1799 will have the value 1 as expected.
1801 <tag><tt/.sizeof(Data)/</tag>
1802 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1803 the segment is switched after entry, this data is emitted into another
1808 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1810 Builtin function. The function accepts a string and an index as
1811 arguments and returns the value of the character at the given position
1812 as an integer value. The index is zero based.
1818 ; Check if the argument string starts with '#'
1819 .if (.strat (Arg, 0) = '#')
1826 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1828 Builtin function. It expects a format string as first argument. The number
1829 and type of the following arguments depend on the format string. The format
1830 string is similar to the one of the C <tt/printf/ function. Missing things
1831 are: Length modifiers, variable width.
1833 The result of the function is a string.
1840 ; Generate an identifier:
1841 .ident (.sprintf ("%s%03d", "label", num)):
1845 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1847 Builtin function. The function accepts an argument in braces and converts
1848 this argument into a string constant. The argument may be an identifier, or
1849 a constant numeric value.
1851 Since you can use a string in the first place, the use of the function may
1852 not be obvious. However, it is useful in macros, or more complex setups.
1857 ; Emulate other assemblers:
1859 .segment .string(name)
1864 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1866 Builtin function. The function accepts a string argument in braces and
1867 evaluates to the length of the string.
1871 The following macro encodes a string as a pascal style string with
1872 a leading length byte.
1876 .byte .strlen(Arg), Arg
1881 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1883 Builtin function. The function accepts a token list in braces. The function
1884 result is the number of tokens given as argument. The token list may
1885 optionally be enclosed into curly braces which are not considered part of
1886 the list and not counted. Enclosement in curly braces allows the inclusion
1887 of tokens that would otherwise terminate the list (the closing right paren
1892 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1893 with the normal 6502 instructions). To translate it into two separate 8 bit
1894 load instructions, the '#' token has to get stripped from the argument:
1898 .if (.match (.mid (0, 1, {arg}), #))
1899 ; ldax called with immediate operand
1900 lda #<(.right (.tcount ({arg})-1, {arg}))
1901 ldx #>(.right (.tcount ({arg})-1, {arg}))
1909 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1911 Builtin function. Matches two token lists against each other. This is
1912 most useful within macros, since macros are not stored as strings, but
1918 .XMATCH(<token list #1>, <token list #2>)
1921 Both token list may contain arbitrary tokens with the exception of the
1922 terminator token (comma resp. right parenthesis) and
1929 The token lists may optionally be enclosed into curly braces. This allows
1930 the inclusion of tokens that would otherwise terminate the list (the closing
1931 right paren in the given case). Often a macro parameter is used for any of
1934 The function compares tokens <em/and/ token values. If you need a function
1935 that just compares the type of tokens, have a look at the <tt><ref
1936 id=".MATCH" name=".MATCH"></tt> function.
1938 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1942 <sect>Control commands<label id="control-commands"><p>
1944 Here's a list of all control commands and a description, what they do:
1947 <sect1><tt>.A16</tt><label id=".A16"><p>
1949 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1951 Note: This command will not emit any code, it will tell the assembler to
1952 create 16 bit operands for immediate accumulator addressing mode.
1954 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1957 <sect1><tt>.A8</tt><label id=".A8"><p>
1959 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1961 Note: This command will not emit any code, it will tell the assembler to
1962 create 8 bit operands for immediate accu addressing mode.
1964 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1967 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1969 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1970 may be used for better readability if the data words are address values. In
1971 65816 mode, the address is forced to be 16 bit wide to fit into the current
1972 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1973 must be followed by a sequence of (not necessarily constant) expressions.
1978 .addr $0D00, $AF13, _Clear
1981 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1985 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1987 Align data to a given boundary. The command expects a constant integer
1988 argument in the range 1 ... 65536, plus an optional second argument
1989 in byte range. If there is a second argument, it is used as fill value,
1990 otherwise the value defined in the linker configuration file is used
1991 (the default for this value is zero).
1993 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1994 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1995 number of bytes, since that would break address calculations within the
1996 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1997 of the alignment, because that allows the number of fill bytes to be
1998 calculated in advance by the assembler. You are therefore required to
1999 specify a matching alignment for the segment in the linker config. The
2000 linker will output a warning if the alignment of the segment is less than
2001 what is necessary to have a correct alignment in the object file.
2009 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
2010 commands with different arguments. To allow the assembler to calculate the
2011 number of fill bytes in advance, the alignment of the segment must be a
2012 multiple of each of the alignment factors. This may result in unexpectedly
2013 large alignments for the segment within the module.
2024 For the assembler to be able to align correctly, the segment must be aligned
2025 to the least common multiple of 15 and 18 which is 90. The assembler will
2026 calculate this automatically and will mark the segment with this value.
2028 Unfortunately, the combined alignment may get rather large without the user
2029 knowing about it, wasting space in the final executable. If we add another
2030 alignment to the example above
2041 the assembler will force a segment alignment to the least common multiple of
2042 15, 18 and 251 - which is 22590. To protect the user against errors, the
2043 assembler will issue a warning when the combined alignment exceeds 256. The
2044 command line option <tt><ref id="option--large-alignment"
2045 name="--large-alignment"></tt> will disable this warning.
2047 Please note that with alignments that are a power of two (which were the
2048 only alignments possible in older versions of the assembler), the problem is
2049 less severe, because the least common multiple of powers to the same base is
2050 always the larger one.
2054 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
2056 Define a string with a trailing zero.
2061 Msg: .asciiz "Hello world"
2064 This will put the string "Hello world" followed by a binary zero into
2065 the current segment. There may be more strings separated by commas, but
2066 the binary zero is only appended once (after the last one).
2069 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2071 Add an assertion. The command is followed by an expression, an action
2072 specifier, and an optional message that is output in case the assertion
2073 fails. If no message was given, the string "Assertion failed" is used. The
2074 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2075 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2076 assembler if possible, and in any case, it's also passed to the linker in
2077 the object file (if one is generated). The linker will then evaluate the
2078 expression when segment placement has been done.
2083 .assert * = $8000, error, "Code not at $8000"
2086 The example assertion will check that the current location is at $8000,
2087 when the output file is written, and abort with an error if this is not
2088 the case. More complex expressions are possible. The action specifier
2089 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2090 an error message. In the latter case, generation of the output file is
2091 suppressed in both the assembler and linker.
2094 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2096 Is followed by a plus or a minus character. When switched on (using a
2097 +), undefined symbols are automatically marked as import instead of
2098 giving errors. When switched off (which is the default so this does not
2099 make much sense), this does not happen and an error message is
2100 displayed. The state of the autoimport flag is evaluated when the
2101 complete source was translated, before outputting actual code, so it is
2102 <em/not/ possible to switch this feature on or off for separate sections
2103 of code. The last setting is used for all symbols.
2105 You should probably not use this switch because it delays error
2106 messages about undefined symbols until the link stage. The cc65
2107 compiler (which is supposed to produce correct assembler code in all
2108 circumstances, something which is not true for most assembler
2109 programmers) will insert this command to avoid importing each and every
2110 routine from the runtime library.
2115 .autoimport + ; Switch on auto import
2118 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2120 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2121 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2122 the operator '^' prepended to each expression in its list.
2127 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2129 TableLookupLo: .lobytes MyTable
2130 TableLookupHi: .hibytes MyTable
2131 TableLookupBank: .bankbytes MyTable
2134 which is equivalent to
2137 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2138 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2139 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2142 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2143 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2144 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2147 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2149 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2150 so this is a shortcut for
2156 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2159 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2161 Define byte sized data. Must be followed by a sequence of (byte ranged)
2162 expressions or strings.
2168 .byt "world", $0D, $00
2172 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2174 Switch on or off case sensitivity on identifiers. The default is off
2175 (that is, identifiers are case sensitive), but may be changed by the
2176 -i switch on the command line.
2177 The command must be followed by a '+' or '-' character to switch the
2178 option on or off respectively.
2183 .case - ; Identifiers are not case sensitive
2187 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2189 Apply a custom mapping for characters. The command is followed by two
2190 numbers. The first one is the index of the source character (range 0..255);
2191 the second one is the mapping (range 0..255). The mapping applies to all
2192 character and string constants <em/when/ they generate output; and, overrides
2193 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2194 command line switch.
2198 .charmap $41, $61 ; Map 'A' to 'a'
2202 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2204 Switch to the CODE segment. The name of the CODE segment is always
2205 "CODE", so this is a shortcut for
2211 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2214 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2216 Export a symbol and mark it in a special way. The linker is able to build
2217 tables of all such symbols. This may be used to automatically create a list
2218 of functions needed to initialize linked library modules.
2220 Note: The linker has a feature to build a table of marked routines, but it
2221 is your code that must call these routines, so just declaring a symbol with
2222 <tt/.CONDES/ does nothing by itself.
2224 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2225 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2226 is implied by <tt/.CONDES/.
2228 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2229 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2230 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2231 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2232 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2233 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2234 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2236 After the type, an optional priority may be specified. Higher numeric values
2237 mean higher priority. If no priority is given, the default priority of 7 is
2238 used. Be careful when assigning priorities to your own module constructors
2239 so they won't interfere with the ones in the cc65 library.
2244 .condes ModuleInit, constructor
2245 .condes ModInit, 0, 16
2248 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2249 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2250 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2251 name="Module constructors/destructors"> explaining the feature in more
2255 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2257 Export a symbol and mark it as a module constructor. This may be used
2258 together with the linker to build a table of constructor subroutines that
2259 are called by the startup code.
2261 Note: The linker has a feature to build a table of marked routines, but it
2262 is your code that must call these routines, so just declaring a symbol as
2263 constructor does nothing by itself.
2265 A constructor is always exported as an absolute (16 bit) symbol. You don't
2266 need to use an additional <tt/.export/ statement, this is implied by
2267 <tt/.constructor/. It may have an optional priority that is separated by a
2268 comma. Higher numeric values mean a higher priority. If no priority is
2269 given, the default priority of 7 is used. Be careful when assigning
2270 priorities to your own module constructors so they won't interfere with the
2271 ones in the cc65 library.
2276 .constructor ModuleInit
2277 .constructor ModInit, 16
2280 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2281 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2282 <ref id="condes" name="Module constructors/destructors"> explaining the
2283 feature in more detail.
2286 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2288 Switch to the DATA segment. The name of the DATA segment is always
2289 "DATA", so this is a shortcut for
2295 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2298 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2300 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2301 create word sized data in native 65XX format). Must be followed by a
2302 sequence of (word ranged) expressions.
2310 This will emit the bytes
2316 into the current segment in that order.
2319 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2321 Switch on or off debug info generation. The default is off (that is,
2322 the object file will not contain debug infos), but may be changed by the
2323 -g switch on the command line.
2324 The command must be followed by a '+' or '-' character to switch the
2325 option on or off respectively.
2330 .debuginfo + ; Generate debug info
2334 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2336 Start a define style macro definition. The command is followed by an
2337 identifier (the macro name) and optionally by a list of formal arguments
2340 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2341 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2344 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2345 section <ref id="macros" name="Macros">.
2348 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2350 Delete a classic macro (defined with <tt><ref id=".MACRO"
2351 name=".MACRO"></tt>) . The command is followed by the name of an
2352 existing macro. Its definition will be deleted together with the name.
2353 If necessary, another macro with this name may be defined later.
2355 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2356 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2357 <tt><ref id=".MACRO" name=".MACRO"></tt>
2359 See also section <ref id="macros" name="Macros">.
2362 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2364 Builtin function. The function expects an identifier as argument in braces.
2365 The argument is evaluated, and the function yields "true" if the identifier
2366 is a symbol that is already defined somewhere in the source file up to the
2367 current position. Otherwise the function yields false. As an example, the
2368 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2375 <sect1><tt>.DEFINEDMACRO</tt><label id=".DEFINEDMACRO"><p>
2377 Builtin function. The function expects an identifier as argument in braces.
2378 The argument is evaluated, and the function yields "true" if the identifier
2379 has already been defined as the name of a macro. Otherwise the function yields
2388 .if .definedmacro(add)
2397 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2399 Export a symbol and mark it as a module destructor. This may be used
2400 together with the linker to build a table of destructor subroutines that
2401 are called by the startup code.
2403 Note: The linker has a feature to build a table of marked routines, but it
2404 is your code that must call these routines, so just declaring a symbol as
2405 constructor does nothing by itself.
2407 A destructor is always exported as an absolute (16 bit) symbol. You don't
2408 need to use an additional <tt/.export/ statement, this is implied by
2409 <tt/.destructor/. It may have an optional priority that is separated by a
2410 comma. Higher numerical values mean a higher priority. If no priority is
2411 given, the default priority of 7 is used. Be careful when assigning
2412 priorities to your own module destructors so they won't interfere with the
2413 ones in the cc65 library.
2418 .destructor ModuleDone
2419 .destructor ModDone, 16
2422 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2423 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2424 section <ref id="condes" name="Module constructors/destructors"> explaining
2425 the feature in more detail.
2428 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2430 Define dword sized data (4 bytes) Must be followed by a sequence of
2436 .dword $12344512, $12FA489
2440 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2442 Conditional assembly: Reverse the current condition.
2445 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2447 Conditional assembly: Reverse current condition and test a new one.
2450 <sect1><tt>.END</tt><label id=".END"><p>
2452 Forced end of assembly. Assembly stops at this point, even if the command
2453 is read from an include file.
2456 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2458 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2461 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2463 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2464 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2467 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2469 Marks the end of a macro definition.
2471 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2472 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2473 <tt><ref id=".MACRO" name=".MACRO"></tt>
2475 See also section <ref id="macros" name="Macros">.
2478 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2480 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2483 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2485 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2488 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2490 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2493 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2495 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2496 command and the separate section named <ref id="structs" name=""Structs
2500 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2502 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2503 command and the separate section named <ref id="structs" name=""Structs
2507 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2509 Start an enumeration. This directive is very similar to the C <tt/enum/
2510 keyword. If a name is given, a new scope is created for the enumeration,
2511 otherwise the enumeration members are placed in the enclosing scope.
2513 In the enumeration body, symbols are declared. The first symbol has a value
2514 of zero, and each following symbol will get the value of the preceding plus
2515 one. This behaviour may be overridden by an explicit assignment. Two symbols
2516 may have the same value.
2528 Above example will create a new scope named <tt/errorcodes/ with three
2529 symbols in it that get the values 0, 1 and 2 respectively. Another way
2530 to write this would have been:
2540 Please note that explicit scoping must be used to access the identifiers:
2543 .word errorcodes::no_error
2546 A more complex example:
2555 EWOULDBLOCK = EAGAIN
2559 In this example, the enumeration does not have a name, which means that the
2560 members will be visible in the enclosing scope and can be used in this scope
2561 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2562 The value for the following members is incremented by one, so <tt/EOK/ would
2563 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2564 override for the value using an already defined symbol.
2567 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2569 Force an assembly error. The assembler will output an error message
2570 preceded by "User error". Assembly is continued but no object file will
2573 This command may be used to check for initial conditions that must be
2574 set before assembling a source file.
2584 .error "Must define foo or bar!"
2588 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2589 <tt><ref id=".OUT" name=".OUT"></tt>,
2590 <tt><ref id=".WARNING" name=".WARNING"></tt>
2593 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2595 Abort a macro expansion immediately. This command is often useful in
2598 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2599 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2600 <tt><ref id=".MACRO" name=".MACRO"></tt>
2602 See also section <ref id="macros" name="Macros">.
2605 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2607 Make symbols accessible from other modules. Must be followed by a comma
2608 separated list of symbols to export, with each one optionally followed by an
2609 address specification and (also optional) an assignment. Using an additional
2610 assignment in the export statement allows to define and export a symbol in
2611 one statement. The default is to export the symbol with the address size it
2612 actually has. The assembler will issue a warning, if the symbol is exported
2613 with an address size smaller than the actual address size.
2620 .export foobar: far = foo * bar
2621 .export baz := foobar, zap: far = baz - bar
2624 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2627 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2630 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2632 Make symbols accessible from other modules. Must be followed by a comma
2633 separated list of symbols to export. The exported symbols are explicitly
2634 marked as zero page symbols. An assignment may be included in the
2635 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2642 .exportzp baz := $02
2645 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2648 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2650 Define far (24 bit) address data. The command must be followed by a
2651 sequence of (not necessarily constant) expressions.
2656 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2659 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2662 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2664 Force an assembly error and terminate assembly. The assembler will output an
2665 error message preceded by "User error" and will terminate assembly
2668 This command may be used to check for initial conditions that must be
2669 set before assembling a source file.
2679 .fatal "Must define foo or bar!"
2683 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2684 <tt><ref id=".OUT" name=".OUT"></tt>,
2685 <tt><ref id=".WARNING" name=".WARNING"></tt>
2688 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2690 This directive may be used to enable one or more compatibility features
2691 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2692 possible, it may be useful when porting sources written for other
2693 assemblers. There is no way to switch a feature off, once you have
2694 enabled it, so using
2700 will enable the feature until end of assembly is reached.
2702 The following features are available:
2706 <tag><tt>addrsize</tt><label id="addrsize"></tag>
2708 Enables the .ADDRSIZE pseudo function. This function is experimental and not enabled by default.
2710 See also: <tt><ref id=".ADDRSIZE" name=".ADDRSIZE"></tt>
2712 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2714 Accept the at character (`@') as a valid character in identifiers. The
2715 at character is not allowed to start an identifier, even with this
2718 <tag><tt>bracket_as_indirect</tt><label id="bracket_as_indirect"></tag>
2720 Use <tt>[]</tt> instead of <tt>()</tt> for the indirect addressing modes.
2730 <em/Note:/ This should not be used in 65186 mode because it conflicts with
2731 the 65816 instruction syntax for far addressing. See the section covering
2732 <tt/<ref id="address-sizes" name="address sizes">/ for more information.
2734 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2736 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2737 comment terminators. Note that C comments may not be nested. There's also a
2738 pitfall when using C like comments: All statements must be terminated by
2739 "end-of-line". Using C like comments, it is possible to hide the newline,
2740 which results in error messages. See the following non working example:
2743 lda #$00 /* This comment hides the newline
2747 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2749 Accept the dollar sign (`$') as a valid character in identifiers. The
2750 dollar character is not allowed to start an identifier, even with this
2753 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2755 The dollar sign may be used as an alias for the star (`*'), which
2756 gives the value of the current PC in expressions.
2757 Note: Assignment to the pseudo variable is not allowed.
2759 <tag><tt>force_range</tt><label id="force_range"></tag>
2761 Force expressions into their valid range for immediate addressing and
2762 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2763 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2764 since it will completely disable error checks.
2766 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2768 Allow labels without a trailing colon. These labels are only accepted,
2769 if they start at the beginning of a line (no leading white space).
2771 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2773 Accept the dot (`.') as the first character of an identifier. This may be
2774 used for example to create macro names that start with a dot emulating
2775 control directives of other assemblers. Note however, that none of the
2776 reserved keywords built into the assembler, that starts with a dot, may be
2777 overridden. When using this feature, you may also get into trouble if
2778 later versions of the assembler define new keywords starting with a dot.
2780 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2782 Accept single quotes as well as double quotes as terminators for char
2785 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2787 Accept single quotes as well as double quotes as terminators for string
2790 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2792 Accept single quoted character constants where the terminating quote is
2797 <em/Note:/ This does not work in conjunction with <tt/.FEATURE
2798 loose_string_term/, since in this case the input would be ambiguous.
2800 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2802 This feature makes relocatable/absolute mode local to the current segment.
2803 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2804 effect will only enable absolute mode for the current segment. Dito for
2805 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2807 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2809 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2810 is enabled). Such an assignment is handled identical to the <tt><ref
2811 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2812 removing the lines with the assignments may also be an option when porting
2813 code written for older assemblers).
2815 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2817 Allow the use of instructions names as names for macros and symbols. This
2818 makes it possible to "overload" instructions by defining a macro with the
2819 same name. This does also make it possible to introduce hard to find errors
2820 in your code, so be careful!
2822 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2824 Allow underlines within numeric constants. These may be used for grouping
2825 the digits of numbers for easier reading.
2828 .feature underline_in_numbers
2829 .word %1100001110100101
2830 .word %1100_0011_1010_0101 ; Identical but easier to read
2835 It is also possible to specify features on the command line using the
2836 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2837 This is useful when translating sources written for older assemblers, when
2838 you don't want to change the source code.
2840 As an example, to translate sources written for Andre Fachats xa65
2841 assembler, the features
2844 labels_without_colons, pc_assignment, loose_char_term
2847 may be helpful. They do not make ca65 completely compatible, so you may not
2848 be able to translate the sources without changes, even when enabling these
2849 features. However, I have found several sources that translate without
2850 problems when enabling these features on the command line.
2853 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2855 Insert an option string into the object file. There are two forms of
2856 this command, one specifies the option by a keyword, the second
2857 specifies it as a number. Since usage of the second one needs knowledge
2858 of the internal encoding, its use is not recommended and I will only
2859 describe the first form here.
2861 The command is followed by one of the keywords
2869 a comma and a string. The option is written into the object file
2870 together with the string value. This is currently unidirectional and
2871 there is no way to actually use these options once they are in the
2877 .fileopt comment, "Code stolen from my brother"
2878 .fileopt compiler, "BASIC 2.0"
2879 .fopt author, "J. R. User"
2883 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2885 Import an absolute symbol from another module. The command is followed by a
2886 comma separated list of symbols to import. The command is similar to <tt>
2887 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2888 written to the generated object file, even if the symbol is never referenced
2889 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2890 references for unused symbols).
2895 .forceimport needthisone, needthistoo
2898 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2901 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2903 Declare symbols as global. Must be followed by a comma separated list of
2904 symbols to declare. Symbols from the list, that are defined somewhere in the
2905 source, are exported, all others are imported. Additional <tt><ref
2906 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2907 name=".EXPORT"></tt> commands for the same symbol are allowed.
2916 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2918 Declare symbols as global. Must be followed by a comma separated list of
2919 symbols to declare. Symbols from the list, that are defined somewhere in the
2920 source, are exported, all others are imported. Additional <tt><ref
2921 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2922 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2923 in the list are explicitly marked as zero page symbols.
2931 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2933 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2934 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2935 the operator '>' prepended to each expression in its list.
2940 .lobytes $1234, $2345, $3456, $4567
2941 .hibytes $fedc, $edcb, $dcba, $cba9
2944 which is equivalent to
2947 .byte $34, $45, $56, $67
2948 .byte $fe, $ed, $dc, $cb
2954 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2956 TableLookupLo: .lobytes MyTable
2957 TableLookupHi: .hibytes MyTable
2960 which is equivalent to
2963 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2964 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2967 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2968 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2969 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2972 <sect1><tt>.I16</tt><label id=".I16"><p>
2974 Valid only in 65816 mode. Switch the index registers to 16 bit.
2976 Note: This command will not emit any code, it will tell the assembler to
2977 create 16 bit operands for immediate operands.
2979 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2980 name=".SMART"></tt> commands.
2983 <sect1><tt>.I8</tt><label id=".I8"><p>
2985 Valid only in 65816 mode. Switch the index registers to 8 bit.
2987 Note: This command will not emit any code, it will tell the assembler to
2988 create 8 bit operands for immediate operands.
2990 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2991 name=".SMART"></tt> commands.
2994 <sect1><tt>.IF</tt><label id=".IF"><p>
2996 Conditional assembly: Evaluate an expression and switch assembler output
2997 on or off depending on the expression. The expression must be a constant
2998 expression, that is, all operands must be defined.
3000 A expression value of zero evaluates to FALSE, any other value evaluates
3004 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
3006 Conditional assembly: Check if there are any remaining tokens in this line,
3007 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
3008 condition is not true, further lines are not assembled until an <tt><ref
3009 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3010 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3012 This command is often used to check if a macro parameter was given. Since an
3013 empty macro parameter will evaluate to nothing, the condition will evaluate
3014 to TRUE if an empty parameter was given.
3028 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3031 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
3033 Conditional assembly: Evaluate an expression and switch assembler output
3034 on or off depending on the constness of the expression.
3036 A const expression evaluates to to TRUE, a non const expression (one
3037 containing an imported or currently undefined symbol) evaluates to
3040 See also: <tt><ref id=".CONST" name=".CONST"></tt>
3043 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
3045 Conditional assembly: Check if a symbol is defined. Must be followed by
3046 a symbol name. The condition is true if the the given symbol is already
3047 defined, and false otherwise.
3049 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3052 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
3054 Conditional assembly: Check if there are any remaining tokens in this line,
3055 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
3056 condition is not true, further lines are not assembled until an <tt><ref
3057 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3058 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3060 This command is often used to check if a macro parameter was given.
3061 Since an empty macro parameter will evaluate to nothing, the condition
3062 will evaluate to FALSE if an empty parameter was given.
3075 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3078 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
3080 Conditional assembly: Check if a symbol is defined. Must be followed by
3081 a symbol name. The condition is true if the the given symbol is not
3082 defined, and false otherwise.
3084 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3087 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
3089 Conditional assembly: Check if a symbol is referenced. Must be followed
3090 by a symbol name. The condition is true if if the the given symbol was
3091 not referenced before, and false otherwise.
3093 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3096 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
3098 Conditional assembly: Check if the assembler is currently in 6502 mode
3099 (see <tt><ref id=".P02" name=".P02"></tt> command).
3102 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
3104 Conditional assembly: Check if the assembler is currently in 65816 mode
3105 (see <tt><ref id=".P816" name=".P816"></tt> command).
3108 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
3110 Conditional assembly: Check if the assembler is currently in 65C02 mode
3111 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3114 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3116 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3117 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3120 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3122 Conditional assembly: Check if a symbol is referenced. Must be followed
3123 by a symbol name. The condition is true if if the the given symbol was
3124 referenced before, and false otherwise.
3126 This command may be used to build subroutine libraries in include files
3127 (you may use separate object modules for this purpose too).
3132 .ifref ToHex ; If someone used this subroutine
3133 ToHex: tay ; Define subroutine
3139 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3142 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3144 Import a symbol from another module. The command is followed by a comma
3145 separated list of symbols to import, with each one optionally followed by
3146 an address specification.
3152 .import bar: zeropage
3155 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3158 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3160 Import a symbol from another module. The command is followed by a comma
3161 separated list of symbols to import. The symbols are explicitly imported
3162 as zero page symbols (that is, symbols with values in byte range).
3170 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3173 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3175 Include a file as binary data. The command expects a string argument
3176 that is the name of a file to include literally in the current segment.
3177 In addition to that, a start offset and a size value may be specified,
3178 separated by commas. If no size is specified, all of the file from the
3179 start offset to end-of-file is used. If no start position is specified
3180 either, zero is assumed (which means that the whole file is inserted).
3185 ; Include whole file
3186 .incbin "sprites.dat"
3188 ; Include file starting at offset 256
3189 .incbin "music.dat", $100
3191 ; Read 100 bytes starting at offset 200
3192 .incbin "graphics.dat", 200, 100
3196 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3198 Include another file. Include files may be nested up to a depth of 16.
3207 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3209 Export a symbol and mark it as an interruptor. This may be used together
3210 with the linker to build a table of interruptor subroutines that are called
3213 Note: The linker has a feature to build a table of marked routines, but it
3214 is your code that must call these routines, so just declaring a symbol as
3215 interruptor does nothing by itself.
3217 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3218 need to use an additional <tt/.export/ statement, this is implied by
3219 <tt/.interruptor/. It may have an optional priority that is separated by a
3220 comma. Higher numeric values mean a higher priority. If no priority is
3221 given, the default priority of 7 is used. Be careful when assigning
3222 priorities to your own module constructors so they won't interfere with the
3223 ones in the cc65 library.
3228 .interruptor IrqHandler
3229 .interruptor Handler, 16
3232 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3233 section <ref id="condes" name="Module constructors/destructors"> explaining
3234 the feature in more detail.
3237 <sect1><tt>.ISMNEM, .ISMNEMONIC</tt><label id=".ISMNEMONIC"><p>
3239 Builtin function. The function expects an identifier as argument in braces.
3240 The argument is evaluated, and the function yields "true" if the identifier
3241 is defined as an instruction mnemonic that is recognized by the assembler.
3245 .if .not .ismnemonic(ina)
3254 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3256 Switch on or off line continuations using the backslash character
3257 before a newline. The option is off by default.
3258 Note: Line continuations do not work in a comment. A backslash at the
3259 end of a comment is treated as part of the comment and does not trigger
3261 The command must be followed by a '+' or '-' character to switch the
3262 option on or off respectively.
3267 .linecont + ; Allow line continuations
3270 #$20 ; This is legal now
3274 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3276 Enable output to the listing. The command must be followed by a boolean
3277 switch ("on", "off", "+" or "-") and will enable or disable listing
3279 The option has no effect if the listing is not enabled by the command line
3280 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3281 to the listing file, if the counter is greater than zero, and suppressed if
3282 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3288 .list on ; Enable listing output
3292 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3294 Set, how many bytes are shown in the listing for one source line. The
3295 default is 12, so the listing will show only the first 12 bytes for any
3296 source line that generates more than 12 bytes of code or data.
3297 The directive needs an argument, which is either "unlimited", or an
3298 integer constant in the range 4..255.
3303 .listbytes unlimited ; List all bytes
3304 .listbytes 12 ; List the first 12 bytes
3305 .incbin "data.bin" ; Include large binary file
3309 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3311 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3312 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3313 the operator '<' prepended to each expression in its list.
3318 .lobytes $1234, $2345, $3456, $4567
3319 .hibytes $fedc, $edcb, $dcba, $cba9
3322 which is equivalent to
3325 .byte $34, $45, $56, $67
3326 .byte $fe, $ed, $dc, $cb
3332 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3334 TableLookupLo: .lobytes MyTable
3335 TableLookupHi: .hibytes MyTable
3338 which is equivalent to
3341 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3342 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3345 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3346 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3347 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3350 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3352 This command may only be used inside a macro definition. It declares a
3353 list of identifiers as local to the macro expansion.
3355 A problem when using macros are labels: Since they don't change their name,
3356 you get a "duplicate symbol" error if the macro is expanded the second time.
3357 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3358 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3361 Some other assemblers start a new lexical block inside a macro expansion.
3362 This has some drawbacks however, since that will not allow <em/any/ symbol
3363 to be visible outside a macro, a feature that is sometimes useful. The
3364 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3365 to address the problem.
3367 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3371 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3373 Defines the character that start "cheap" local labels. You may use one
3374 of '@' and '?' as start character. The default is '@'.
3376 Cheap local labels are labels that are visible only between two non
3377 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3378 using explicit lexical nesting.
3385 Clear: lda #$00 ; Global label
3386 ?Loop: sta Mem,y ; Local label
3390 Sub: ... ; New global label
3391 bne ?Loop ; ERROR: Unknown identifier!
3395 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3397 Insert a predefined macro package. The command is followed by an
3398 identifier specifying the macro package to insert. Available macro
3402 atari Defines the scrcode macro.
3403 cbm Defines the scrcode macro.
3404 cpu Defines constants for the .CPU variable.
3405 generic Defines generic macroes like add, sub, and blt.
3406 longbranch Defines conditional long-jump macroes.
3409 Including a macro package twice, or including a macro package that
3410 redefines already existing macros will lead to an error.
3415 .macpack longbranch ; Include macro package
3417 cmp #$20 ; Set condition codes
3418 jne Label ; Jump long on condition
3421 Macro packages are explained in more detail in section <ref
3422 id="macropackages" name="Macro packages">.
3425 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3427 Start a classic macro definition. The command is followed by an identifier
3428 (the macro name) and optionally by a comma separated list of identifiers
3429 that are macro parameters. A macro definition is terminated by <tt><ref
3430 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3435 .macro ldax arg ; Define macro ldax
3440 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3441 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3442 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3444 See also section <ref id="macros" name="Macros">.
3447 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3449 Start a section of absolute code. The command is followed by a constant
3450 expression that gives the new PC counter location for which the code is
3451 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3454 By default, absolute/relocatable mode is global (valid even when switching
3455 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3456 it can be made segment local.
3458 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3459 code at a specific address is the job of the linker, not the assembler, so
3460 there is usually no reason to assemble code to a specific address.
3465 .org $7FF ; Emit code starting at $7FF
3469 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3471 Output a string to the console without producing an error. This command
3472 is similar to <tt/.ERROR/, however, it does not force an assembler error
3473 that prevents the creation of an object file.
3478 .out "This code was written by the codebuster(tm)"
3481 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3482 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3483 <tt><ref id=".WARNING" name=".WARNING"></tt>
3486 <sect1><tt>.P02</tt><label id=".P02"><p>
3488 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3489 instructions. This is the default if not overridden by the
3490 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3492 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3493 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3496 <sect1><tt>.P816</tt><label id=".P816"><p>
3498 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3499 6502 instruction sets.
3501 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3502 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3505 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3507 Set the page length for the listing. Must be followed by an integer
3508 constant. The value may be "unlimited", or in the range 32 to 127. The
3509 statement has no effect if no listing is generated. The default value is -1
3510 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3511 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3512 after assembly is complete, you cannot use multiple line lengths with one
3513 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3518 .pagelength 66 ; Use 66 lines per listing page
3520 .pagelength unlimited ; Unlimited page length
3524 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3526 Enable the 65C02 instructions set. This instruction set includes all
3527 6502 and 65SC02 instructions.
3529 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3530 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3533 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3535 Pop the last CPU setting from the stack, and activate it.
3537 This command will switch back to the CPU that was last pushed onto the CPU
3538 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3539 remove this entry from the stack.
3541 The assembler will print an error message if the CPU stack is empty when
3542 this command is issued.
3544 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3545 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3548 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3550 Pop the last pushed segment from the stack, and set it.
3552 This command will switch back to the segment that was last pushed onto the
3553 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3554 command, and remove this entry from the stack.
3556 The assembler will print an error message if the segment stack is empty
3557 when this command is issued.
3559 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3562 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3564 Start a nested lexical level with the given name and adds a symbol with this
3565 name to the enclosing scope. All new symbols from now on are in the local
3566 lexical level and are accessible from outside only via <ref id="scopesyntax"
3567 name="explicit scope specification">. Symbols defined outside this local
3568 level may be accessed as long as their names are not used for new symbols
3569 inside the level. Symbols names in other lexical levels do not clash, so you
3570 may use the same names for identifiers. The lexical level ends when the
3571 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3572 may be nested up to a depth of 16 (this is an artificial limit to protect
3573 against errors in the source).
3575 Note: Macro names are always in the global level and in a separate name
3576 space. There is no special reason for this, it's just that I've never
3577 had any need for local macro definitions.
3582 .proc Clear ; Define Clear subroutine, start new level
3584 L1: sta Mem,y ; L1 is local and does not cause a
3585 ; duplicate symbol error if used in other
3588 bne L1 ; Reference local symbol
3590 .endproc ; Leave lexical level
3593 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3597 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3599 Enable the 65SC02 instructions set. This instruction set includes all
3602 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3603 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3606 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3608 Push the currently active CPU onto a stack. The stack has a size of 8
3611 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3612 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3613 later, without knowledge of the current CPU setting.
3615 The assembler will print an error message if the CPU stack is already full,
3616 when this command is issued.
3618 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3619 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3622 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3624 Push the currently active segment onto a stack. The entries on the stack
3625 include the name of the segment and the segment type. The stack has a size
3628 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3629 to switch to another segment and to restore the old segment later, without
3630 even knowing the name and type of the current segment.
3632 The assembler will print an error message if the segment stack is already
3633 full, when this command is issued.
3635 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3638 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3640 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3641 name=".ORG"></tt> command.
3644 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3646 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3647 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3648 a constant expression that tells how many times the commands in the body
3649 should get repeated. Optionally, a comma and an identifier may be specified.
3650 If this identifier is found in the body of the repeat statement, it is
3651 replaced by the current repeat count (starting with zero for the first time
3652 the body is repeated).
3654 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3655 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3656 level will be used, not the one from the outer level.
3660 The following macro will emit a string that is "encrypted" in that all
3661 characters of the string are XORed by the value $55.
3665 .repeat .strlen(Arg), I
3666 .byte .strat(Arg, I) ^ $55
3671 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3674 <sect1><tt>.RES</tt><label id=".RES"><p>
3676 Reserve storage. The command is followed by one or two constant
3677 expressions. The first one is mandatory and defines, how many bytes of
3678 storage should be defined. The second, optional expression must by a
3679 constant byte value that will be used as value of the data. If there
3680 is no fill value given, the linker will use the value defined in the
3681 linker configuration file (default: zero).
3686 ; Reserve 12 bytes of memory with value $AA
3691 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3693 Switch to the RODATA segment. The name of the RODATA segment is always
3694 "RODATA", so this is a shortcut for
3700 The RODATA segment is a segment that is used by the compiler for
3701 readonly data like string constants.
3703 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3706 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3708 Start a nested lexical level with the given name. All new symbols from now
3709 on are in the local lexical level and are accessible from outside only via
3710 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3711 outside this local level may be accessed as long as their names are not used
3712 for new symbols inside the level. Symbols names in other lexical levels do
3713 not clash, so you may use the same names for identifiers. The lexical level
3714 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3715 read. Lexical levels may be nested up to a depth of 16 (this is an
3716 artificial limit to protect against errors in the source).
3718 Note: Macro names are always in the global level and in a separate name
3719 space. There is no special reason for this, it's just that I've never
3720 had any need for local macro definitions.
3725 .scope Error ; Start new scope named Error
3727 File = 1 ; File error
3728 Parse = 2 ; Parse error
3729 .endscope ; Close lexical level
3732 lda #Error::File ; Use symbol from scope Error
3735 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3739 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3741 Switch to another segment. Code and data is always emitted into a
3742 segment, that is, a named section of data. The default segment is
3743 "CODE". There may be up to 254 different segments per object file
3744 (and up to 65534 per executable). There are shortcut commands for
3745 the most common segments ("ZEROPAGE", "CODE", "RODATA", "DATA", and "BSS").
3747 The command is followed by a string containing the segment name (there are
3748 some constraints for the name - as a rule of thumb use only those segment
3749 names that would also be valid identifiers). There may also be an optional
3750 address size separated by a colon. See the section covering <tt/<ref
3751 id="address-sizes" name="address sizes">/ for more information.
3753 The default address size for a segment depends on the memory model specified
3754 on the command line. The default is "absolute", which means that you don't
3755 have to use an address size modifier in most cases.
3757 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3758 That is, the segment will reside somewhere in core memory outside the zero
3759 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3760 page and direct (short) addressing is possible for data in this segment.
3762 Beware: Only labels in a segment with the zeropage attribute are marked
3763 as reachable by short addressing. The `*' (PC counter) operator will
3764 work as in other segments and will create absolute variable values.
3766 Please note that a segment cannot have two different address sizes. A
3767 segment specified as zeropage cannot be declared as being absolute later.
3772 .segment "ROM2" ; Switch to ROM2 segment
3773 .segment "ZP2": zeropage ; New direct segment
3774 .segment "ZP2" ; Ok, will use last attribute
3775 .segment "ZP2": absolute ; Error, redecl mismatch
3778 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3779 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt>, <tt><ref
3780 id=".RODATA" name=".RODATA"></tt>, and <tt><ref id=".ZEROPAGE"
3781 name=".ZEROPAGE"></tt>
3784 <sect1><tt>.SET</tt><label id=".SET"><p>
3786 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3787 name="Numeric variables"> for a full description.
3790 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3792 Switch the CPU instruction set. The command is followed by a string that
3793 specifies the CPU. Possible values are those that can also be supplied to
3794 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3795 namely: 6502, 6502X, 65SC02, 65C02, 65816 and HuC6280.
3797 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3798 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3799 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3800 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3801 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3802 <tt><ref id=".P02" name=".P02"></tt>,
3803 <tt><ref id=".P816" name=".P816"></tt>,
3804 <tt><ref id=".PC02" name=".PC02"></tt>,
3805 <tt><ref id=".PSC02" name=".PSC02"></tt>
3808 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3810 Switch on or off smart mode. The command must be followed by a '+' or '-'
3811 character to switch the option on or off respectively. The default is off
3812 (that is, the assembler doesn't try to be smart), but this default may be
3813 changed by the -s switch on the command line.
3815 In smart mode the assembler will do the following:
3818 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3819 and update the operand sizes accordingly. If the operand of such an
3820 instruction cannot be evaluated by the assembler (for example, because
3821 the operand is an imported symbol), a warning is issued. Beware: Since
3822 the assembler cannot trace the execution flow this may lead to false
3823 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3824 instructions to tell the assembler about the current settings.
3825 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3826 used within a procedure declared as <tt/far/, or if the procedure has
3827 no explicit address specification, but it is <tt/far/ because of the
3835 .smart - ; Stop being smart
3838 See: <tt><ref id=".A16" name=".A16"></tt>,
3839 <tt><ref id=".A8" name=".A8"></tt>,
3840 <tt><ref id=".I16" name=".I16"></tt>,
3841 <tt><ref id=".I8" name=".I8"></tt>
3844 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3846 Starts a struct definition. Structs are covered in a separate section named
3847 <ref id="structs" name=""Structs and unions"">.
3849 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3850 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3851 <tt><ref id=".UNION" name=".UNION"></tt>
3854 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3856 Allocate space for a struct or union.
3867 .tag Point ; Allocate 4 bytes
3871 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3873 Delete a define style macro definition. The command is followed by an
3874 identifier which specifies the name of the macro to delete. Macro
3875 replacement is switched of when reading the token following the command
3876 (otherwise the macro name would be replaced by its replacement list).
3878 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3879 section <ref id="macros" name="Macros">.
3882 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3884 Starts a union definition. Unions are covered in a separate section named
3885 <ref id="structs" name=""Structs and unions"">.
3887 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3888 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3889 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3892 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3894 Force an assembly warning. The assembler will output a warning message
3895 preceded by "User warning". This warning will always be output, even if
3896 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3897 command line option.
3899 This command may be used to output possible problems when assembling
3908 .warning "Forward jump in jne, cannot optimize!"
3918 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3919 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3920 <tt><ref id=".OUT" name=".OUT"></tt>
3923 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3925 Define word sized data. Must be followed by a sequence of (word ranged,
3926 but not necessarily constant) expressions.
3931 .word $0D00, $AF13, _Clear
3935 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3937 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3938 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3942 .segment "ZEROPAGE": zeropage
3945 Because of the "zeropage" attribute, labels declared in this segment are
3946 addressed using direct addressing mode if possible. You <em/must/ instruct
3947 the linker to place this segment somewhere in the address range 0..$FF
3948 otherwise you will get errors.
3950 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3954 <sect>Macros<label id="macros"><p>
3957 <sect1>Introduction<p>
3959 Macros may be thought of as "parametrized super instructions". Macros are
3960 sequences of tokens that have a name. If that name is used in the source
3961 file, the macro is "expanded", that is, it is replaced by the tokens that
3962 were specified when the macro was defined.
3965 <sect1>Macros without parameters<p>
3967 In its simplest form, a macro does not have parameters. Here's an
3971 .macro asr ; Arithmetic shift right
3972 cmp #$80 ; Put bit 7 into carry
3973 ror ; Rotate right with carry
3977 The macro above consists of two real instructions, that are inserted into
3978 the code, whenever the macro is expanded. Macro expansion is simply done
3979 by using the name, like this:
3988 <sect1>Parametrized macros<p>
3990 When using macro parameters, macros can be even more useful:
4004 When calling the macro, you may give a parameter, and each occurrence of
4005 the name "addr" in the macro definition will be replaced by the given
4024 A macro may have more than one parameter, in this case, the parameters
4025 are separated by commas. You are free to give less parameters than the
4026 macro actually takes in the definition. You may also leave intermediate
4027 parameters empty. Empty parameters are replaced by empty space (that is,
4028 they are removed when the macro is expanded). If you have a look at our
4029 macro definition above, you will see, that replacing the "addr" parameter
4030 by nothing will lead to wrong code in most lines. To help you, writing
4031 macros with a variable parameter list, there are some control commands:
4033 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
4034 returns true, if there are any tokens on the remainder of the line. Since
4035 empty parameters are replaced by nothing, this may be used to test if a given
4036 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
4039 Look at this example:
4042 .macro ldaxy a, x, y
4055 That macro may be called as follows:
4058 ldaxy 1, 2, 3 ; Load all three registers
4060 ldaxy 1, , 3 ; Load only a and y
4062 ldaxy , , 3 ; Load y only
4065 There's another helper command for determining which macro parameters are
4066 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>. That command is
4067 replaced by the parameter count given, <em/including/ explicitly empty
4071 ldaxy 1 ; .PARAMCOUNT = 1
4072 ldaxy 1,,3 ; .PARAMCOUNT = 3
4073 ldaxy 1,2 ; .PARAMCOUNT = 2
4074 ldaxy 1, ; .PARAMCOUNT = 2
4075 ldaxy 1,2,3 ; .PARAMCOUNT = 3
4078 Macro parameters may optionally be enclosed into curly braces. This allows the
4079 inclusion of tokens that would otherwise terminate the parameter (the comma in
4080 case of a macro parameter).
4083 .macro foo arg1, arg2
4087 foo ($00,x) ; Two parameters passed
4088 foo {($00,x)} ; One parameter passed
4091 In the first case, the macro is called with two parameters: '<tt/($00/'
4092 and '<tt/x)/'. The comma is not passed to the macro, because it is part of the
4093 calling sequence, not the parameters.
4095 In the second case, '<tt/($00,x)/' is passed to the macro; this time,
4096 including the comma.
4099 <sect1>Detecting parameter types<p>
4101 Sometimes it is nice to write a macro that acts differently depending on the
4102 type of the argument supplied. An example would be a macro that loads a 16 bit
4103 value from either an immediate operand, or from memory. The <tt/<ref
4104 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
4105 functions will allow you to do exactly this:
4109 .if (.match (.left (1, {arg}), #))
4111 lda #<(.right (.tcount ({arg})-1, {arg}))
4112 ldx #>(.right (.tcount ({arg})-1, {arg}))
4114 ; assume absolute or zero page
4121 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4122 check if its argument begins with a hash mark. If so, two immediate loads are
4123 emitted, Otherwise a load from an absolute zero page memory location is
4124 assumed. Please note how the curly braces are used to enclose parameters to
4125 pseudo functions handling token lists. This is necessary, because the token
4126 lists may include commas or parens, which would be treated by the assembler
4129 The macro can be used as
4134 ldax #$1234 ; X=$12, A=$34
4136 ldax foo ; X=$56, A=$78
4140 <sect1>Recursive macros<p>
4142 Macros may be used recursively:
4145 .macro push r1, r2, r3
4154 There's also a special macro command to help with writing recursive macros:
4155 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>. That command will stop macro
4156 expansion immediately:
4159 .macro push r1, r2, r3, r4, r5, r6, r7
4161 ; First parameter is empty
4167 push r2, r3, r4, r5, r6, r7
4171 When expanding that macro, the expansion will push all given parameters
4172 until an empty one is encountered. The macro may be called like this:
4175 push $20, $21, $32 ; Push 3 ZP locations
4176 push $21 ; Push one ZP location
4180 <sect1>Local symbols inside macros<p>
4182 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4183 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4184 Have a look at the inc16 macro above. Here is it again:
4198 If you have a closer look at the code, you will notice, that it could be
4199 written more efficiently, like this:
4210 But imagine what happens, if you use this macro twice? Since the label "Skip"
4211 has the same name both times, you get a "duplicate symbol" error. Without a
4212 way to circumvent this problem, macros are not as useful, as they could be.
4213 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4214 It declares one or more symbols as local to the macro expansion. The names of
4215 local variables are replaced by a unique name in each separate macro
4216 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4220 .local Skip ; Make Skip a local symbol
4224 Skip: ; Not visible outside
4228 Another solution is of course to start a new lexical block inside the macro
4229 that hides any labels:
4243 <sect1>C style macros<p>
4245 Starting with version 2.5 of the assembler, there is a second macro type
4246 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4247 similar to the classic macro type described above, but behaviour is sometimes
4252 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4253 span more than a line. You may use line continuation (see <tt><ref
4254 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4255 more than one line for increased readability, but the macro itself
4256 may not contain an end-of-line token.
4258 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4259 the name space with classic macros, but they are detected and replaced
4260 at the scanner level. While classic macros may be used in every place,
4261 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4262 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4263 they are more versatile in some situations.
4265 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4266 parameters. While classic macros may have empty parameters, this is
4267 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4268 For this macro type, the number of actual parameters must match
4269 exactly the number of formal parameters.
4271 To make this possible, formal parameters are enclosed in braces when
4272 defining the macro. If there are no parameters, the empty braces may
4275 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4276 contain end-of-line tokens, there are things that cannot be done. They
4277 may not contain several processor instructions for example. So, while
4278 some things may be done with both macro types, each type has special
4279 usages. The types complement each other.
4283 Let's look at a few examples to make the advantages and disadvantages
4286 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4287 following <tt/.DEFINE/:
4292 foo EQU $1234 ; This is accepted now
4295 You may use the directive to define string constants used elsewhere:
4298 ; Define the version number
4299 .define VERSION "12.3a"
4305 Macros with parameters may also be useful:
4308 .define DEBUG(message) .out message
4310 DEBUG "Assembling include file #3"
4313 Note that, while formal parameters have to be placed in braces, this is
4314 not true for the actual parameters. Beware: Since the assembler cannot
4315 detect the end of one parameter, only the first token is used. If you
4316 don't like that, use classic macros instead:
4319 .macro DEBUG message
4324 (That is an example where a problem can be solved with both macro types).
4327 <sect1>Characters in macros<p>
4329 When using the <ref id="option-t" name="-t"> option, characters are translated
4330 into the target character set of the specific machine. However, this happens
4331 as late as possible. This means that strings are translated if they are part
4332 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4333 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4334 used as part of an expression.
4336 This behaviour is very intuitive outside of macros but may be confusing when
4337 doing more complex macros. If you compare characters against numeric values,
4338 be sure to take the translation into account.
4341 <sect1>Deleting macros<p>
4343 Macros can be deleted. This will not work if the macro that should be deleted
4344 is currently expanded as in the following non-working example:
4348 .delmacro notworking
4351 notworking ; Will not work
4354 The commands to delete classic and define style macros differ. Classic macros
4355 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4356 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4357 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4365 .byte value ; Emit one byte with value 1
4366 mac ; Emit another byte with value 2
4371 .byte value ; Error: Unknown identifier
4372 mac ; Error: Missing ":"
4375 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4376 the name of such a macro is replaced by its replacement list on a very low
4377 level. To get the actual name, macro replacement has to be switched off when
4378 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4379 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4380 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4381 different commands increases flexibility.
4385 <sect>Macro packages<label id="macropackages"><p>
4387 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4388 macro packages may be included with just one command. Available macro packages
4392 <sect1><tt>.MACPACK generic</tt><p>
4394 This macro package defines macroes that are useful in almost any program.
4395 Currently defined macroes are:
4398 .macro add Arg ; add without carry
4403 .macro sub Arg ; subtract without borrow
4408 .macro bge Arg ; branch on greater-than or equal
4412 .macro blt Arg ; branch on less-than
4416 .macro bgt Arg ; branch on greater-than
4423 .macro ble Arg ; branch on less-than or equal
4428 .macro bnz Arg ; branch on not zero
4432 .macro bze Arg ; branch on zero
4438 <sect1><tt>.MACPACK longbranch</tt><p>
4440 This macro package defines long conditional jumps. They are named like the
4441 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4442 definition for the "<tt/jeq/" macro, the other macros are built using the same
4447 .if .def(Target) .and ((*+2)-(Target) <= 127)
4456 All macros expand to a short branch, if the label is already defined (back
4457 jump) and is reachable with a short jump. Otherwise the macro expands to a
4458 conditional branch with the branch condition inverted, followed by an absolute
4459 jump to the actual branch target.
4461 The package defines the following macros:
4464 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4469 <sect1><tt>.MACPACK apple2</tt><p>
4471 This macro package defines a macro named <tt/scrcode/. It takes a string
4472 as argument and places this string into memory translated into screen codes.
4475 <sect1><tt>.MACPACK atari</tt><p>
4477 This macro package defines a macro named <tt/scrcode/. It takes a string
4478 as argument and places this string into memory translated into screen codes.
4481 <sect1><tt>.MACPACK cbm</tt><p>
4483 This macro package defines a macro named <tt/scrcode/. It takes a string
4484 as argument and places this string into memory translated into screen codes.
4487 <sect1><tt>.MACPACK cpu</tt><p>
4489 This macro package does not define any macros but constants used to examine
4490 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4491 each supported CPU a constant similar to
4502 is defined. These constants may be used to determine the exact type of the
4503 currently enabled CPU. In addition to that, for each CPU instruction set,
4504 another constant is defined:
4515 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4516 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4517 currently enabled CPU supports a specific instruction set. For example the
4518 65C02 supports all instructions of the 65SC02 CPU, so it has the
4519 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4523 .if (.cpu .bitand CPU_ISET_65SC02)
4531 it is possible to determine if the
4537 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4538 CPUs (the latter two are upwards compatible to the 65SC02).
4541 <sect1><tt>.MACPACK module</tt><p>
4543 This macro package defines a macro named <tt/module_header/. It takes an
4544 identifier as argument and is used to define the header of a module both
4545 in the dynamic and static variant.
4549 <sect>Predefined constants<label id="predefined-constants"><p>
4551 For better orthogonality, the assembler defines similar symbols as the
4552 compiler, depending on the target system selected:
4555 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4556 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4557 <item><tt/__ATARI5200__/ - Target system is <tt/atari5200/
4558 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4559 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4560 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4561 <item><tt/__BBC__/ - Target system is <tt/bbc/
4562 <item><tt/__C128__/ - Target system is <tt/c128/
4563 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4564 <item><tt/__C64__/ - Target system is <tt/c64/
4565 <item><tt/__CBM__/ - Target is a Commodore system
4566 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4567 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4568 <item><tt/__GEOS__/ - Target is a GEOS system
4569 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4570 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4571 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4572 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4573 <item><tt/__NES__/ - Target system is <tt/nes/
4574 <item><tt/__OSIC1P__/ - Target system is <tt/osic1p/
4575 <item><tt/__PET__/ - Target system is <tt/pet/
4576 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4577 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4578 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4579 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4580 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4584 <sect>Structs and unions<label id="structs"><p>
4586 <sect1>Structs and unions Overview<p>
4588 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4589 are to some degree comparable to their C counterparts. Both have a list of
4590 members. Each member allocates storage and may optionally have a name, which,
4591 in case of a struct, is the offset from the beginning and, in case of a union,
4595 <sect1>Declaration<p>
4597 Here is an example for a very simple struct with two members and a total size
4607 A union shares the total space between all its members, its size is the same
4608 as that of the largest member. The offset of all members relative to the union
4618 A struct or union must not necessarily have a name. If it is anonymous, no
4619 local scope is opened, the identifiers used to name the members are placed
4620 into the current scope instead.
4622 A struct may contain unnamed members and definitions of local structs. The
4623 storage allocators may contain a multiplier, as in the example below:
4628 .word 2 ; Allocate two words
4635 <sect1>The <tt/.TAG/ keyword<p>
4637 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4638 for an already defined struct or unions within another struct:
4652 Space for a struct or union may be allocated using the <ref id=".TAG"
4653 name=".TAG"> directive.
4659 Currently, members are just offsets from the start of the struct or union. To
4660 access a field of a struct, the member offset has to be added to the address
4661 of the struct itself:
4664 lda C+Circle::Radius ; Load circle radius into A
4667 This may change in a future version of the assembler.
4670 <sect1>Limitations<p>
4672 Structs and unions are currently implemented as nested symbol tables (in fact,
4673 they were a by-product of the improved scoping rules). Currently, the
4674 assembler has no idea of types. This means that the <ref id=".TAG"
4675 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4676 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4677 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4678 this structure accessible by using the '::' operator.
4682 <sect>Module constructors/destructors<label id="condes"><p>
4684 <em>Note:</em> This section applies mostly to C programs, so the explanation
4685 below uses examples from the C libraries. However, the feature may also be
4686 useful for assembler programs.
4689 <sect1>Module constructors/destructors Overview<p>
4691 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4692 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4693 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4694 special way. The linker is able to generate tables with all functions of a
4695 specific type. Such a table will <em>only</em> include symbols from object
4696 files that are linked into a specific executable. This may be used to add
4697 initialization and cleanup code for library modules, or a table of interrupt
4700 The C heap functions are an example where module initialization code is used.
4701 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4702 variables that contain the start and the end of the heap, pointers to the free
4703 list and so on. Since the end of the heap depends on the size and start of the
4704 stack, it must be initialized at runtime. However, initializing these
4705 variables for programs that do not use the heap are a waste of time and
4708 So the central module defines a function that contains initialization code and
4709 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4710 this module is added to an executable by the linker, the initialization
4711 function will be placed into the table of constructors by the linker. The C
4712 startup code will call all constructors before <tt/main/ and all destructors
4713 after <tt/main/, so without any further work, the heap initialization code is
4714 called once the module is linked in.
4716 While it would be possible to add explicit calls to initialization functions
4717 in the startup code, the new approach has several advantages:
4721 If a module is not included, the initialization code is not linked in and not
4722 called. So you don't pay for things you don't need.
4725 Adding another library that needs initialization does not mean that the
4726 startup code has to be changed. Before we had module constructors and
4727 destructors, the startup code for all systems had to be adjusted to call the
4728 new initialization code.
4731 The feature saves memory: Each additional initialization function needs just
4732 two bytes in the table (a pointer to the function).
4737 <sect1>Calling order<p>
4739 The symbols are sorted in increasing priority order by the linker when using
4740 one of the builtin linker configurations, so the functions with lower
4741 priorities come first and are followed by those with higher priorities. The C
4742 library runtime subroutine that walks over the function tables calls the
4743 functions starting from the top of the table - which means that functions with
4744 a high priority are called first.
4746 So when using the C runtime, functions are called with high priority functions
4747 first, followed by low priority functions.
4752 When using these special symbols, please take care of the following:
4757 The linker will only generate function tables, it will not generate code to
4758 call these functions. If you're using the feature in some other than the
4759 existing C environments, you have to write code to call all functions in a
4760 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4761 in the C runtime for an example on how to do this.
4764 The linker will only add addresses of functions that are in modules linked to
4765 the executable. This means that you have to be careful where to place the
4766 condes functions. If initialization or an irq handler is needed for a group of
4767 functions, be sure to place the function into a module that is linked in
4768 regardless of which function is called by the user.
4771 The linker will generate the tables only when requested to do so by the
4772 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4773 be requested separately.
4776 Constructors and destructors may have priorities. These priorities determine
4777 the order of the functions in the table. If your initialization or cleanup code
4778 does depend on other initialization or cleanup code, you have to choose the
4779 priority for the functions accordingly.
4782 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4783 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4784 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4785 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4786 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4787 (interruptor). The linker generates a separate table for each type on request.
4792 <sect>Porting sources from other assemblers<p>
4794 Sometimes it is necessary to port code written for older assemblers to ca65.
4795 In some cases, this can be done without any changes to the source code by
4796 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4797 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4800 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4801 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4802 done by the linker. Most other assemblers generate absolute code, placement is
4803 done within the assembler and there is no external linker.
4805 In general it is not a good idea to write new code using the emulation
4806 features of the assembler, but there may be situations where even this rule is
4811 You need to use some of the ca65 emulation features to simulate the behaviour
4812 of such simple assemblers.
4815 <item>Prepare your sourcecode like this:
4818 ; if you want TASS style labels without colons
4819 .feature labels_without_colons
4821 ; if you want TASS style character constants
4822 ; ("a" instead of the default 'a')
4823 .feature loose_char_term
4825 .word *+2 ; the cbm load address
4830 notice that the two emulation features are mostly useful for porting
4831 sources originally written in/for TASS, they are not needed for the
4832 actual "simple assembler operation" and are not recommended if you are
4833 writing new code from scratch.
4835 <item>Replace all program counter assignments (which are not possible in ca65
4836 by default, and the respective emulation feature works different from what
4837 you'd expect) by another way to skip to memory locations, for example the
4838 <tt><ref id=".RES" name=".RES"></tt> directive.
4842 .res $2000-* ; reserve memory up to $2000
4845 Please note that other than the original TASS, ca65 can never move the program
4846 counter backwards - think of it as if you are assembling to disk with TASS.
4848 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4849 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4850 of <tt/.goto/, everything involving loops must be replaced by
4851 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4853 <item>To assemble code to a different address than it is executed at, use the
4854 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4855 <tt/.offs/-constructs.
4862 .reloc ; back to normal
4865 <item>Then assemble like this:
4868 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4871 Note that you need to use the actual start address minus two, since two bytes
4872 are used for the cbm load address.
4879 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4880 Bassewitz. For usage of the binaries and/or sources the following
4881 conditions do apply:
4883 This software is provided 'as-is', without any expressed or implied
4884 warranty. In no event will the authors be held liable for any damages
4885 arising from the use of this software.
4887 Permission is granted to anyone to use this software for any purpose,
4888 including commercial applications, and to alter it and redistribute it
4889 freely, subject to the following restrictions:
4892 <item> The origin of this software must not be misrepresented; you must not
4893 claim that you wrote the original software. If you use this software
4894 in a product, an acknowledgment in the product documentation would be
4895 appreciated but is not required.
4896 <item> Altered source versions must be plainly marked as such, and must not
4897 be misrepresented as being the original software.
4898 <item> This notice may not be removed or altered from any source