1 <!doctype linuxdoc system>
4 <title>ca65 Users Guide
5 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
6 <date>2000-07-19, 2000-11-29, 2001-10-02, 2005-09-08
9 ca65 is a powerful macro assembler for the 6502, 65C02 and 65816 CPUs. It is
10 used as a companion assembler for the cc65 crosscompiler, but it may also be
11 used as a standalone product.
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
22 compiler, originally developed by John R. Dunning. I had some problems with
23 ra65 and the copyright does not permit some things which I wanted to be
24 possible, so I decided to write a completely new assembler/linker/archiver
25 suite for the cc65 compiler. ca65 is part of this suite.
27 Some parts of the assembler (code generation and some routines for symbol
28 table handling) are taken from an older crossassembler named a816 written
29 by me a long time ago.
32 <sect1>Design criteria<p>
34 Here's a list of the design criteria, that I considered important for the
39 <item> The assembler must support macros. Macros are not essential, but they
40 make some things easier, especially when you use the assembler in the
41 backend of a compiler.
42 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
43 thinking about a 65816 backend for the C compiler, and even my old
44 a816 assembler had support for these CPUs, so this wasn't really a
46 <item> The assembler must produce relocatable code. This is necessary for the
47 compiler support, and it is more convenient.
48 <item> Conditional assembly must be supported. This is a must for bigger
49 projects written in assembler (like Elite128).
50 <item> The assembler must support segments, and it must support more than
51 three segments (this is the count, most other assemblers support).
52 Having more than one code segments helps developing code for systems
53 with a divided ROM area (like the C64).
54 <item> The linker must be able to resolve arbitrary expressions. It should
55 be able to get things like
62 <item> True lexical nesting for symbols. This is very convenient for larger
64 <item> "Cheap" local symbols without lexical nesting for those quick, late
66 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
67 introduced the concept into the object file format use by the new cc65
69 <item> The assembler will be a one pass assembler. There was no real need for
70 this decision, but I've written several multipass assemblers, and it
71 started to get boring. A one pass assembler needs much more elaborated
72 data structures, and because of that it's much more fun:-)
73 <item> Non-GPLed code that may be used in any project without restrictions or
74 fear of "GPL infecting" other code.
82 <sect1>Command line option overview<p>
84 The assembler accepts the following options:
87 ---------------------------------------------------------------------------
88 Usage: ca65 [options] file
90 -D name[=value] Define a symbol
91 -I dir Set an include directory search path
92 -U Mark unresolved symbols as import
93 -V Print the assembler version
94 -W n Set warning level n
95 -g Add debug info to object file
97 -i Ignore case of symbols
98 -l name Create a listing file if assembly was ok
99 -mm model Set the memory model
100 -o name Name the output file
102 -t sys Set the target system
103 -v Increase verbosity
106 --auto-import Mark unresolved symbols as import
107 --bin-include-dir dir Set a search path for binary includes
108 --cpu type Set cpu type
109 --create-dep name Create a make dependency file
110 --create-full-dep name Create a full make dependency file
111 --debug-info Add debug info to object file
112 --feature name Set an emulation feature
113 --forget-inc-paths Forget include search paths
114 --help Help (this text)
115 --ignore-case Ignore case of symbols
116 --include-dir dir Set an include directory search path
117 --large-alignment Don't warn about large alignments
118 --listing name Create a listing file if assembly was ok
119 --list-bytes n Maximum number of bytes per listing line
120 --macpack-dir dir Set a macro package directory
121 --memory-model model Set the memory model
122 --pagelength n Set the page length for the listing
123 --smart Enable smart mode
124 --target sys Set the target system
125 --verbose Increase verbosity
126 --version Print the assembler version
127 ---------------------------------------------------------------------------
131 <sect1>Command line options in detail<p>
133 Here is a description of all the command line options:
137 <label id="option--bin-include-dir">
138 <tag><tt>--bin-include-dir dir</tt></tag>
140 Name a directory which is searched for binary include files. The option
141 may be used more than once to specify more than one directory to search. The
142 current directory is always searched first before considering any
143 additional directories. See also the section about <ref id="search-paths"
144 name="search paths">.
147 <label id="option--cpu">
148 <tag><tt>--cpu type</tt></tag>
150 Set the default for the CPU type. The option takes a parameter, which
153 6502, 65SC02, 65C02, 65816, sunplus, sweet16, HuC6280
155 The sunplus cpu is not available in the freeware version, because the
156 instruction set is "proprietary and confidential".
159 <label id="option-create-dep">
160 <tag><tt>--create-dep name</tt></tag>
162 Tells the assembler to generate a file containing the dependency list for
163 the assembled module in makefile syntax. The output is written to a file
164 with the given name. The output does not include files passed via debug
165 information to the assembler.
168 <label id="option-create-full-dep">
169 <tag><tt>--create-full-dep name</tt></tag>
171 Tells the assembler to generate a file containing the dependency list for
172 the assembled module in makefile syntax. The output is written to a file
173 with the given name. The output does include files passed via debug
174 information to the assembler.
177 <label id="option--feature">
178 <tag><tt>--feature name</tt></tag>
180 Enable an emulation feature. This is identical as using <tt/.FEATURE/
181 in the source with two exceptions: Feature names must be lower case, and
182 each feature must be specified by using an extra <tt/--feature/ option,
183 comma separated lists are not allowed.
185 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
186 command for a list of emulation features.
189 <label id="option--forget-inc-paths">
190 <tag><tt>--forget-inc-paths</tt></tag>
192 Forget the builtin include paths. This is most useful when building
193 customized assembler modules, in which case the standard header files should
197 <label id="option-g">
198 <tag><tt>-g, --debug-info</tt></tag>
200 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
201 used, the assembler will add a section to the object file that contains
202 all symbols (including local ones) together with the symbol values and
203 source file positions. The linker will put these additional symbols into
204 the VICE label file, so even local symbols can be seen in the VICE
208 <label id="option-h">
209 <tag><tt>-h, --help</tt></tag>
211 Print the short option summary shown above.
214 <label id="option-i">
215 <tag><tt>-i, --ignore-case</tt></tag>
217 This option makes the assembler case insensitive on identifiers and labels.
218 This option will override the default, but may itself be overridden by the
219 <tt><ref id=".CASE" name=".CASE"></tt> control command.
222 <label id="option-l">
223 <tag><tt>-l name, --listing name</tt></tag>
225 Generate an assembler listing with the given name. A listing file will
226 never be generated in case of assembly errors.
229 <label id="option--large-alignment">
230 <tag><tt>--large-alignment</tt></tag>
232 Disable warnings about a large combined alignment. See the discussion of the
233 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
236 <label id="option--list-bytes">
237 <tag><tt>--list-bytes n</tt></tag>
239 Set the maximum number of bytes printed in the listing for one line of
240 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
241 for more information. The value zero can be used to encode an unlimited
242 number of printed bytes.
245 <label id="option--macpack-dir">
246 <tag><tt>--macpack-dir dir</tt></tag>
248 This options allows to specify a directory containing macro files that are
249 used instead of the builtin images when a <tt><ref id=".MACPACK"
250 name=".MACPACK"></tt> directive is encountered. If <tt>--macpack-dir</tt>
251 was specified, a <tt>.mac</tt> extension is added to the package name and
252 the resulting file is loaded from the given directory. This is most useful
253 when debugging the builtin macro packages.
256 <label id="option-mm">
257 <tag><tt>-mm model, --memory-model model</tt></tag>
259 Define the default memory model. Possible model specifiers are near, far and
263 <label id="option-o">
264 <tag><tt>-o name</tt></tag>
266 The default output name is the name of the input file with the extension
267 replaced by ".o". If you don't like that, you may give another name with
268 the -o option. The output file will be placed in the same directory as
269 the source file, or, if -o is given, the full path in this name is used.
272 <label id="option--pagelength">
273 <tag><tt>--pagelength n</tt></tag>
275 sets the length of a listing page in lines. See the <tt><ref
276 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
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 directory.
374 <item>A compiled-in directory, which is often <tt>/usr/lib/cc65/asminc</tt>
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>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
383 Binary include files are searched in the following places:
386 <item>The current directory.
387 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
388 name="--bin-include-dir">/ option on the command line.
393 <sect>Input format<p>
395 <sect1>Assembler syntax<p>
397 The assembler accepts the standard 6502/65816 assembler syntax. One line may
398 contain a label (which is identified by a colon), and, in addition to the
399 label, an assembler mnemonic, a macro, or a control command (see section <ref
400 id="control-commands" name="Control Commands"> for supported control
401 commands). Alternatively, the line may contain a symbol definition using
402 the '=' token. Everything after a semicolon is handled as a comment (that is,
405 Here are some examples for valid input lines:
408 Label: ; A label and a comment
409 lda #$20 ; A 6502 instruction plus comment
410 L1: ldx #$20 ; Same with label
411 L2: .byte "Hello world" ; Label plus control command
412 mymac $20 ; Macro expansion
413 MySym = 3*L1 ; Symbol definition
414 MaSym = Label ; Another symbol
417 The assembler accepts
420 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
421 <tt><ref id=".P02" name=".P02"></tt> command was given).
422 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
423 <ref id="6502X-mode" name="6502X mode">.
424 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
425 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
426 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
427 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
428 <item>all valid 65618 mnemonics when in 65816 mode (after the
429 <tt><ref id=".P816" name=".P816"></tt> command was given).
430 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
431 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
437 In 65816 mode several aliases are accepted in addition to the official
441 BGE is an alias for BCS
442 BLT is an alias for BCC
443 CPA is an alias for CMP
444 DEA is an alias for DEC A
445 INA is an alias for INC A
446 SWA is an alias for XBA
447 TAD is an alias for TCD
448 TAS is an alias for TCS
449 TDA is an alias for TDC
450 TSA is an alias for TSC
455 <sect1>6502X mode<label id="6502X-mode"><p>
457 6502X mode is an extension to the normal 6502 mode. In this mode, several
458 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
459 these instructions are illegal, there are no official mnemonics for them. The
460 unofficial ones are taken from <htmlurl
461 url="http://www.oxyron.de/html/opcodes02.html"
462 name="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
463 ones marked as "stable" are supported. The following table uses information
464 from the mentioned web page, for more information, see there.
467 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
468 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
469 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
470 <item><tt>AXS: X:=A and X-#{imm};</tt>
471 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
472 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
473 <item><tt>LAS: A,X,S:={adr} and S;</tt>
474 <item><tt>LAX: A,X:={adr};</tt>
475 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
476 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
477 <item><tt>SAX: {adr}:=A and X;</tt>
478 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
479 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
484 <sect1>sweet16 mode<label id="sweet16-mode"><p>
486 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
487 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
488 generate code for this pseudo CPU when switched into sweet16 mode. The
489 following is special in sweet16 mode:
493 <item>The '@' character denotes indirect addressing and is no longer available
494 for cheap local labels. If you need cheap local labels, you will have to
495 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
496 name=".LOCALCHAR">/ command.
498 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
499 these identifiers are reserved words.
503 Please note that the assembler does neither supply the interpreter needed for
504 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
505 nor does it call the interpreter. All this must be done by your program. Apple
506 ][ programmers do probably know how to use sweet16 mode.
508 For more information about SWEET 16, see
509 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
510 name="http://www.6502.org/source/interpreters/sweet16.htm">.
513 <sect1>Number format<p>
515 For literal values, the assembler accepts the widely used number formats: A
516 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
517 denotes a binary value, and a bare number is interpreted as a decimal. There
518 are currently no octal values and no floats.
521 <sect1>Conditional assembly<p>
523 Please note that when using the conditional directives (<tt/.IF/ and friends),
524 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
525 that are not assembled. The reason for this behaviour is that the assembler
526 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
527 conversion of the input stream into tokens still takes place. As a consequence
528 conditional assembly directives may <bf/not/ be used to prevent normal text
529 (used as a comment or similar) from being assembled. <p>
535 <sect1>Expression evaluation<p>
537 All expressions are evaluated with (at least) 32 bit precision. An
538 expression may contain constant values and any combination of internal and
539 external symbols. Expressions that cannot be evaluated at assembly time
540 are stored inside the object file for evaluation by the linker.
541 Expressions referencing imported symbols must always be evaluated by the
545 <sect1>Size of an expression result<p>
547 Sometimes, the assembler must know about the size of the value that is the
548 result of an expression. This is usually the case, if a decision has to be
549 made, to generate a zero page or an absolute memory references. In this
550 case, the assembler has to make some assumptions about the result of an
554 <item> If the result of an expression is constant, the actual value is
555 checked to see if it's a byte sized expression or not.
556 <item> If the expression is explicitly casted to a byte sized expression by
557 one of the '>', '<' or '^' operators, it is a byte expression.
558 <item> If this is not the case, and the expression contains a symbol,
559 explicitly declared as zero page symbol (by one of the .importzp or
560 .exportzp instructions), then the whole expression is assumed to be
562 <item> If the expression contains symbols that are not defined, and these
563 symbols are local symbols, the enclosing scopes are searched for a
564 symbol with the same name. If one exists and this symbol is defined,
565 its attributes are used to determine the result size.
566 <item> In all other cases the expression is assumed to be word sized.
569 Note: If the assembler is not able to evaluate the expression at assembly
570 time, the linker will evaluate it and check for range errors as soon as
574 <sect1>Boolean expressions<p>
576 In the context of a boolean expression, any non zero value is evaluated as
577 true, any other value to false. The result of a boolean expression is 1 if
578 it's true, and zero if it's false. There are boolean operators with extreme
579 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
580 operators are shortcut operators. That is, if the result of the expression is
581 already known, after evaluating the left hand side, the right hand side is
585 <sect1>Constant expressions<p>
587 Sometimes an expression must evaluate to a constant without looking at any
588 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
589 that decides if parts of the code are assembled or not. An expression used in
590 the <tt/.IF/ command cannot reference a symbol defined later, because the
591 decision about the <tt/.IF/ must be made at the point when it is read. If the
592 expression used in such a context contains only constant numerical values,
593 there is no problem. When unresolvable symbols are involved it may get harder
594 for the assembler to determine if the expression is actually constant, and it
595 is even possible to create expressions that aren't recognized as constant.
596 Simplifying the expressions will often help.
598 In cases where the result of the expression is not needed immediately, the
599 assembler will delay evaluation until all input is read, at which point all
600 symbols are known. So using arbitrary complex constant expressions is no
601 problem in most cases.
605 <sect1>Available operators<label id="operators"><p>
609 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
610 | Built-in string functions| 0@
612 | Built-in pseudo-variables| 1@
613 | Built-in pseudo-functions| 1@
614 +| Unary positive| 1@
615 -| Unary negative| 1@
617 .BITNOT| Unary bitwise not| 1@
619 .LOBYTE| Unary low-byte operator| 1@
621 .HIBYTE| Unary high-byte operator| 1@
623 .BANKBYTE| Unary bank-byte operator| 1@
625 *| Multiplication| 2@
627 .MOD| Modulo operator| 2@
629 .BITAND| Bitwise and| 2@
631 .BITXOR| Binary bitwise xor| 2@
633 .SHL| Shift-left operator| 2@
635 .SHR| Shift-right operator| 2@
637 +| Binary addition| 3@
638 -| Binary subtraction| 3@
640 .BITOR| Bitwise or| 3@
642 = | Compare operator (equal)| 4@
643 <>| Compare operator (not equal)| 4@
644 <| Compare operator (less)| 4@
645 >| Compare operator (greater)| 4@
646 <=| Compare operator (less or equal)| 4@
647 >=| Compare operator (greater or equal)| 4@
650 .AND| Boolean and| 5@
651 .XOR| Boolean xor| 5@
653 ||<newline>
657 .NOT| Boolean not| 7@<hline>
659 <caption>Available operators, sorted by precedence
662 To force a specific order of evaluation, parentheses may be used, as usual.
666 <sect>Symbols and labels<p>
668 A symbol or label is an identifier that starts with a letter and is followed
669 by letters and digits. Depending on some features enabled (see
670 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
671 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
672 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
673 other characters may be present. Use of identifiers consisting of a single
674 character will not work in all cases, because some of these identifiers are
675 reserved keywords (for example "A" is not a valid identifier for a label,
676 because it is the keyword for the accumulator).
678 The assembler allows you to use symbols instead of naked values to make
679 the source more readable. There are a lot of different ways to define and
680 use symbols and labels, giving a lot of flexibility.
682 <sect1>Numeric constants<p>
684 Numeric constants are defined using the equal sign or the label assignment
685 operator. After doing
691 may use the symbol "two" in every place where a number is expected, and it is
692 evaluated to the value 2 in this context. The label assignment operator is
693 almost identical, but causes the symbol to be marked as a label, so it may be
694 handled differently in a debugger:
700 The right side can of course be an expression:
708 <sect1>Numeric variables<p>
710 Within macros and other control structures (<tt><ref id=".REPEAT"
711 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
712 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
713 symbol that may get assigned a different value later:
717 lda #four ; Loads 4 into A
719 lda #four ; Loads 3 into A
722 Since the value of the symbol can change later, it must be possible to
723 evaluate it when used (no delayed evaluation as with normal symbols). So the
724 expression used as the value must be constant.
726 Following is an example for a macro that generates a different label each time
727 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
728 and a numeric variable named <tt>lcount</tt>.
731 .lcount .set 0 ; Initialize the counter
734 .ident (.sprintf ("L%04X", lcount)):
735 lcount .set lcount + 1
740 <sect1>Standard labels<p>
742 A label is defined by writing the name of the label at the start of the line
743 (before any instruction mnemonic, macro or pseudo directive), followed by a
744 colon. This will declare a symbol with the given name and the value of the
745 current program counter.
748 <sect1>Local labels and symbols<p>
750 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
751 create regions of code where the names of labels and symbols are local to this
752 region. They are not known outside of this region and cannot be accessed from
753 there. Such regions may be nested like PROCEDUREs in Pascal.
755 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
756 directive for more information.
759 <sect1>Cheap local labels<p>
761 Cheap local labels are defined like standard labels, but the name of the
762 label must begin with a special symbol (usually '@', but this can be
763 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
766 Cheap local labels are visible only between two non cheap labels. As soon as a
767 standard symbol is encountered (this may also be a local symbol if inside a
768 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
769 cheap local symbol goes out of scope.
771 You may use cheap local labels as an easy way to reuse common label
772 names like "Loop". Here is an example:
775 Clear: lda #$00 ; Global label
777 @Loop: sta Mem,y ; Local label
781 Sub: ... ; New global label
782 bne @Loop ; ERROR: Unknown identifier!
785 <sect1>Unnamed labels<p>
787 If you really want to write messy code, there are also unnamed labels. These
788 labels do not have a name (you guessed that already, didn't you?). A colon is
789 used to mark the absence of the name.
791 Unnamed labels may be accessed by using the colon plus several minus or plus
792 characters as a label designator. Using the '-' characters will create a back
793 reference (use the n'th label backwards), using '+' will create a forward
794 reference (use the n'th label in forward direction). An example will help to
817 As you can see from the example, unnamed labels will make even short
818 sections of code hard to understand, because you have to count labels
819 to find branch targets (this is the reason why I for my part do
820 prefer the "cheap" local labels). Nevertheless, unnamed labels are
821 convenient in some situations, so it's your decision.
824 <sect1>Using macros to define labels and constants<p>
826 While there are drawbacks with this approach, it may be handy in a few rare
827 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
828 to define symbols or constants that may be used elsewhere. One of the
829 advantages is that you can use it to define string constants (this is not
830 possible with the other symbol types).
832 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
833 so the names do not adhere to scoping, diagnostics may be misleading, there
834 are no symbols to look up in the map file, and there is no debug info.
835 Especially the first problem in the list can lead to very nasty programming
836 errors. Because of these problems, the general advice is, <bf/NOT/ do use
837 <tt/.DEFINE/ if you don't have to.
843 .DEFINE version "SOS V2.3"
845 four = two * two ; Ok
848 .PROC ; Start local scope
849 two = 3 ; Will give "2 = 3" - invalid!
854 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
856 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
857 id="option-g" name="-g"> is given on the command line), global, local and
858 cheap local labels are written to the object file and will be available in the
859 symbol file via the linker. Unnamed labels are not written to the object file,
860 because they don't have a name which would allow to access them.
864 <sect>Scopes<label id="scopes"><p>
866 ca65 implements several sorts of scopes for symbols.
868 <sect1>Global scope<p>
870 All (non cheap local) symbols that are declared outside of any nested scopes
874 <sect1>Cheap locals<p>
876 A special scope is the scope for cheap local symbols. It lasts from one non
877 local symbol to the next one, without any provisions made by the programmer.
878 All other scopes differ in usage but use the same concept internally.
881 <sect1>Generic nested scopes<p>
883 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
884 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
885 The scope can have a name, in which case it is accessible from the outside by
886 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
887 have a name, all symbols created within the scope are local to the scope, and
888 aren't accessible from the outside.
890 A nested scope can access symbols from the local or from enclosing scopes by
891 name without using explicit scope names. In some cases there may be
892 ambiguities, for example if there is a reference to a local symbol that is not
893 yet defined, but a symbol with the same name exists in outer scopes:
905 In the example above, the <tt/lda/ instruction will load the value 3 into the
906 accumulator, because <tt/foo/ is redefined in the scope. However:
918 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
919 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
920 absolute mode is used instead. In fact, the assembler will not use absolute
921 mode by default, but it will search through the enclosing scopes for a symbol
922 with the given name. If one is found, the address size of this symbol is used.
923 This may lead to errors:
935 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
936 instruction, it will search for an already defined symbol <tt/foo/. It will
937 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
938 zeropage symbol. So the assembler will use zeropage addressing mode. If
939 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
940 the address in the <tt/lda/ instruction already translated, but since the new
941 value needs absolute addressing mode, this fails, and an error message "Range
944 Of course the most simple solution for the problem is to move the definition
945 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
946 rare cases when this cannot be done. In these cases, you can use one of the
947 address size override operators:
959 This will cause the <tt/lda/ instruction to be translated using absolute
960 addressing mode, which means changing the symbol reference later does not
964 <sect1>Nested procedures<p>
966 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
967 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
968 name, and a it will introduce a symbol with this name in the enclosing scope.
977 is actually the same as
986 This is the reason why a procedure must have a name. If you want a scope
987 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
989 <bf/Note:/ As you can see from the example above, scopes and symbols live in
990 different namespaces. There can be a symbol named <tt/foo/ and a scope named
991 <tt/foo/ without any conflicts (but see the section titled <ref
992 id="scopesearch" name=""Scope search order"">).
995 <sect1>Structs, unions and enums<p>
997 Structs, unions and enums are explained in a <ref id="structs" name="separate
998 section">, I do only cover them here, because if they are declared with a
999 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
1000 name=".SCOPE">/. However, when no name is specified, the behaviour is
1001 different: In this case, no new scope will be opened, symbols declared within
1002 a struct, union, or enum declaration will then be added to the enclosing scope
1006 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1008 Accessing symbols from other scopes is possible by using an explicit scope
1009 specification, provided that the scope where the symbol lives in has a name.
1010 The namespace token (<tt/::/) is used to access other scopes:
1018 lda foo::bar ; Access foo in scope bar
1021 The only way to deny access to a scope from the outside is to declare a scope
1022 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1024 A special syntax is used to specify the global scope: If a symbol or scope is
1025 preceded by the namespace token, the global scope is searched:
1032 lda #::bar ; Access the global bar (which is 3)
1037 <sect1>Scope search order<label id="scopesearch"><p>
1039 The assembler searches for a scope in a similar way as for a symbol. First, it
1040 looks in the current scope, and then it walks up the enclosing scopes until
1043 However, one important thing to note when using explicit scope syntax is, that
1044 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1045 used without a preceding definition. This means that in the following
1054 lda #foo::bar ; Will load 3, not 2!
1061 the reference to the scope <tt/foo/ will use the global scope, and not the
1062 local one, because the local one is not visible at the point where it is
1065 Things get more complex if a complete chain of scopes is specified:
1076 lda #outer::inner::bar ; 1
1088 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1089 assembler will first search in the local scope for a scope named <tt/outer/.
1090 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1091 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1092 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1093 this scope, the assembler looks for a symbol named <tt/bar/.
1095 Please note that once the anchor scope is found, all following scopes
1096 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1097 assembler will search the scope tree only for the first scope (if it is not
1098 anchored in the root scope). Starting from there on, there is no flexibility,
1099 so if the scope named <tt/outer/ found by the assembler does not contain a
1100 scope named <tt/inner/, this would be an error, even if such a pair does exist
1101 (one level up in global scope).
1103 Ambiguities that may be introduced by this search algorithm may be removed by
1104 anchoring the scope specification in the global scope. In the example above,
1105 if you want to access the "other" symbol <tt/bar/, you would have to write:
1116 lda #::outer::inner::bar ; 2
1129 <sect>Address sizes and memory models<label id="address-sizes"><p>
1131 <sect1>Address sizes<p>
1133 ca65 assigns each segment and each symbol an address size. This is true, even
1134 if the symbol is not used as an address. You may also think of a value range
1135 of the symbol instead of an address size.
1137 Possible address sizes are:
1140 <item>Zeropage or direct (8 bits)
1141 <item>Absolute (16 bits)
1143 <item>Long (32 bits)
1146 Since the assembler uses default address sizes for the segments and symbols,
1147 it is usually not necessary to override the default behaviour. In cases, where
1148 it is necessary, the following keywords may be used to specify address sizes:
1151 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1152 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1153 <item>FAR for far addressing (24 bits).
1154 <item>LONG or DWORD for long addressing (32 bits).
1158 <sect1>Address sizes of segments<p>
1160 The assembler assigns an address size to each segment. Since the
1161 representation of a label within this segment is "segment start + offset",
1162 labels will inherit the address size of the segment they are declared in.
1164 The address size of a segment may be changed, by using an optional address
1165 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1166 an explanation on how this is done.
1169 <sect1>Address sizes of symbols<p>
1174 <sect1>Memory models<p>
1176 The default address size of a segment depends on the memory model used. Since
1177 labels inherit the address size from the segment they are declared in,
1178 changing the memory model is an easy way to change the address size of many
1184 <sect>Pseudo variables<label id="pseudo-variables"><p>
1186 Pseudo variables are readable in all cases, and in some special cases also
1189 <sect1><tt>*</tt><p>
1191 Reading this pseudo variable will return the program counter at the start
1192 of the current input line.
1194 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1195 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1196 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1199 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1201 Reading this pseudo variable will give a constant integer value that
1202 tells which CPU is currently enabled. It can also tell which instruction
1203 set the CPU is able to translate. The value read from the pseudo variable
1204 should be further examined by using one of the constants defined by the
1205 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1207 It may be used to replace the .IFPxx pseudo instructions or to construct
1208 even more complex expressions.
1214 .if (.cpu .bitand CPU_ISET_65816)
1226 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1228 This builtin pseudo variable is only available in macros. It is replaced by
1229 the actual number of parameters that were given in the macro invocation.
1234 .macro foo arg1, arg2, arg3
1235 .if .paramcount <> 3
1236 .error "Too few parameters for macro foo"
1242 See section <ref id="macros" name="Macros">.
1245 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1247 Reading this pseudo variable will give a constant integer value that
1248 represents the current time in POSIX standard (as seconds since the
1251 It may be used to encode the time of translation somewhere in the created
1257 .dword .time ; Place time here
1261 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1263 Reading this pseudo variable will give the assembler version according to
1264 the following formula:
1266 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1268 It may be used to encode the assembler version or check the assembler for
1269 special features not available with older versions.
1273 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1274 reading the pseudo variable <tt/.VERSION/.
1278 <sect>Pseudo functions<label id="pseudo-functions"><p>
1280 Pseudo functions expect their arguments in parenthesis, and they have a result,
1281 either a string or an expression.
1284 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1286 The <tt/.BANK/ function is used to support systems with banked memory. The
1287 argument is an expression with exactly one segment reference - usually a
1288 label. The function result is the value of the <tt/bank/ attribute assigned
1289 to the run memory area of the segment. Please see the linker documentation
1290 for more information about memory areas and their attributes.
1292 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1293 containing specific data is available.
1295 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1296 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1297 name=".LOBYTE"></tt> or similar functions to address just part of it.
1299 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1300 an expression containing <tt/.BANK/ can never be used where a constant known
1301 result is expected (for example with <tt/.RES/).
1318 .byte <.BANK (banked_func_1)
1321 .byte <.BANK (banked_func_2)
1327 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1329 The function returns the bank byte (that is, bits 16-23) of its argument.
1330 It works identical to the '^' operator.
1332 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1333 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1336 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1338 Builtin function. The function evaluates its argument in braces and yields
1339 "false" if the argument is non blank (there is an argument), and "true" if
1340 there is no argument. The token list that makes up the function argument
1341 may optionally be enclosed in curly braces. This allows the inclusion of
1342 tokens that would otherwise terminate the list (the closing right
1343 parenthesis). The curly braces are not considered part of the list, a list
1344 just consisting of curly braces is considered to be empty.
1346 As an example, the <tt/.IFBLANK/ statement may be replaced by
1354 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1356 Builtin string function. The function allows to concatenate a list of string
1357 constants separated by commas. The result is a string constant that is the
1358 concatenation of all arguments. This function is most useful in macros and
1359 when used together with the <tt/.STRING/ builtin function. The function may
1360 be used in any case where a string constant is expected.
1365 .include .concat ("myheader", ".", "inc")
1368 This is the same as the command
1371 .include "myheader.inc"
1375 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1377 Builtin function. The function evaluates its argument in braces and
1378 yields "true" if the argument is a constant expression (that is, an
1379 expression that yields a constant value at assembly time) and "false"
1380 otherwise. As an example, the .IFCONST statement may be replaced by
1387 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1389 The function returns the high byte (that is, bits 8-15) of its argument.
1390 It works identical to the '>' operator.
1392 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1393 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1396 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1398 The function returns the high word (that is, bits 16-31) of its argument.
1400 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1403 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1405 The function expects a string as its argument, and converts this argument
1406 into an identifier. If the string starts with the current <tt/<ref
1407 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1408 identifier, otherwise it will be converted into a normal identifier.
1413 .macro makelabel arg1, arg2
1414 .ident (.concat (arg1, arg2)):
1417 makelabel "foo", "bar"
1419 .word foobar ; Valid label
1423 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1425 Builtin function. Extracts the left part of a given token list.
1430 .LEFT (<int expr>, <token list>)
1433 The first integer expression gives the number of tokens to extract from
1434 the token list. The second argument is the token list itself. The token
1435 list may optionally be enclosed into curly braces. This allows the
1436 inclusion of tokens that would otherwise terminate the list (the closing
1437 right paren in the given case).
1441 To check in a macro if the given argument has a '#' as first token
1442 (immediate addressing mode), use something like this:
1447 .if (.match (.left (1, {arg}), #))
1449 ; ldax called with immediate operand
1457 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1458 name=".RIGHT"></tt> builtin functions.
1461 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1463 The function returns the low byte (that is, bits 0-7) of its argument.
1464 It works identical to the '<' operator.
1466 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1467 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1470 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1472 The function returns the low word (that is, bits 0-15) of its argument.
1474 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1477 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1479 Builtin function. Matches two token lists against each other. This is
1480 most useful within macros, since macros are not stored as strings, but
1486 .MATCH(<token list #1>, <token list #2>)
1489 Both token list may contain arbitrary tokens with the exception of the
1490 terminator token (comma resp. right parenthesis) and
1497 The token lists may optionally be enclosed into curly braces. This allows
1498 the inclusion of tokens that would otherwise terminate the list (the closing
1499 right paren in the given case). Often a macro parameter is used for any of
1502 Please note that the function does only compare tokens, not token
1503 attributes. So any number is equal to any other number, regardless of the
1504 actual value. The same is true for strings. If you need to compare tokens
1505 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1506 name=".XMATCH"></tt> function.
1510 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1511 while honoring the sign bit. The builtin processor instructions will allow
1512 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1513 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1514 to check for this and print and error for invalid calls.
1519 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1520 .error "Syntax error"
1523 cmp #$80 ; Bit 7 into carry
1524 lsr a ; Shift carry into bit 7
1529 The macro will only accept no arguments, or one argument that must be the
1530 reserved keyword "A".
1532 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1535 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1537 Builtin function. The result is the larger of two values.
1542 .MAX (<value #1>, <value #2>)
1548 ; Reserve space for the larger of two data blocks
1549 savearea: .max (.sizeof (foo), .sizeof (bar))
1552 See: <tt><ref id=".MIN" name=".MIN"></tt>
1555 <sect1><tt>.MID</tt><label id=".MID"><p>
1557 Builtin function. Takes a starting index, a count and a token list as
1558 arguments. Will return part of the token list.
1563 .MID (<int expr>, <int expr>, <token list>)
1566 The first integer expression gives the starting token in the list (the first
1567 token has index 0). The second integer expression gives the number of tokens
1568 to extract from the token list. The third argument is the token list itself.
1569 The token list may optionally be enclosed into curly braces. This allows the
1570 inclusion of tokens that would otherwise terminate the list (the closing
1571 right paren in the given case).
1575 To check in a macro if the given argument has a '<tt/#/' as first token
1576 (immediate addressing mode), use something like this:
1581 .if (.match (.mid (0, 1, {arg}), #))
1583 ; ldax called with immediate operand
1591 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1592 name=".RIGHT"></tt> builtin functions.
1595 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1597 Builtin function. The result is the smaller of two values.
1602 .MIN (<value #1>, <value #2>)
1608 ; Reserve space for some data, but 256 bytes minimum
1609 savearea: .min (.sizeof (foo), 256)
1612 See: <tt><ref id=".MAX" name=".MAX"></tt>
1615 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1617 Builtin function. The function expects an identifier as argument in braces.
1618 The argument is evaluated, and the function yields "true" if the identifier
1619 is a symbol that has already been referenced somewhere in the source file up
1620 to the current position. Otherwise the function yields false. As an example,
1621 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1627 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1630 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1632 Builtin function. Extracts the right part of a given token list.
1637 .RIGHT (<int expr>, <token list>)
1640 The first integer expression gives the number of tokens to extract from the
1641 token list. The second argument is the token list itself. The token list
1642 may optionally be enclosed into curly braces. This allows the inclusion of
1643 tokens that would otherwise terminate the list (the closing right paren in
1646 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1647 name=".MID"></tt> builtin functions.
1650 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1652 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1653 argument can be a struct/union, a struct member, a procedure, or a label. In
1654 case of a procedure or label, its size is defined by the amount of data
1655 placed in the segment where the label is relative to. If a line of code
1656 switches segments (for example in a macro) data placed in other segments
1657 does not count for the size.
1659 Please note that a symbol or scope must exist, before it is used together with
1660 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1661 A scope has preference over a symbol with the same name, so if the last part
1662 of a name represents both, a scope and a symbol, the scope is chosen over the
1665 After the following code:
1668 .struct Point ; Struct size = 4
1673 P: .tag Point ; Declare a point
1674 @P: .tag Point ; Declare another point
1686 .data ; Segment switch!!!
1692 <tag><tt/.sizeof(Point)/</tag>
1693 will have the value 4, because this is the size of struct <tt/Point/.
1695 <tag><tt/.sizeof(Point::xcoord)/</tag>
1696 will have the value 2, because this is the size of the member <tt/xcoord/
1697 in struct <tt/Point/.
1699 <tag><tt/.sizeof(P)/</tag>
1700 will have the value 4, this is the size of the data declared on the same
1701 source line as the label <tt/P/, which is in the same segment that <tt/P/
1704 <tag><tt/.sizeof(@P)/</tag>
1705 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1706 does also work for cheap local symbols.
1708 <tag><tt/.sizeof(Code)/</tag>
1709 will have the value 3, since this is amount of data emitted into the code
1710 segment, the segment that was active when <tt/Code/ was entered. Note that
1711 this value includes the amount of data emitted in child scopes (in this
1712 case <tt/Code::Inner/).
1714 <tag><tt/.sizeof(Code::Inner)/</tag>
1715 will have the value 1 as expected.
1717 <tag><tt/.sizeof(Data)/</tag>
1718 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1719 the segment is switched after entry, this data is emitted into another
1724 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1726 Builtin function. The function accepts a string and an index as
1727 arguments and returns the value of the character at the given position
1728 as an integer value. The index is zero based.
1734 ; Check if the argument string starts with '#'
1735 .if (.strat (Arg, 0) = '#')
1742 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1744 Builtin function. It expects a format string as first argument. The number
1745 and type of the following arguments depend on the format string. The format
1746 string is similar to the one of the C <tt/printf/ function. Missing things
1747 are: Length modifiers, variable width.
1749 The result of the function is a string.
1756 ; Generate an identifier:
1757 .ident (.sprintf ("%s%03d", "label", num)):
1761 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1763 Builtin function. The function accepts an argument in braces and converts
1764 this argument into a string constant. The argument may be an identifier, or
1765 a constant numeric value.
1767 Since you can use a string in the first place, the use of the function may
1768 not be obvious. However, it is useful in macros, or more complex setups.
1773 ; Emulate other assemblers:
1775 .segment .string(name)
1780 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1782 Builtin function. The function accepts a string argument in braces and
1783 evaluates to the length of the string.
1787 The following macro encodes a string as a pascal style string with
1788 a leading length byte.
1792 .byte .strlen(Arg), Arg
1797 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1799 Builtin function. The function accepts a token list in braces. The function
1800 result is the number of tokens given as argument. The token list may
1801 optionally be enclosed into curly braces which are not considered part of
1802 the list and not counted. Enclosement in curly braces allows the inclusion
1803 of tokens that would otherwise terminate the list (the closing right paren
1808 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1809 with the normal 6502 instructions). To translate it into two separate 8 bit
1810 load instructions, the '#' token has to get stripped from the argument:
1814 .if (.match (.mid (0, 1, {arg}), #))
1815 ; ldax called with immediate operand
1816 lda #<(.right (.tcount ({arg})-1, {arg}))
1817 ldx #>(.right (.tcount ({arg})-1, {arg}))
1825 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1827 Builtin function. Matches two token lists against each other. This is
1828 most useful within macros, since macros are not stored as strings, but
1834 .XMATCH(<token list #1>, <token list #2>)
1837 Both token list may contain arbitrary tokens with the exception of the
1838 terminator token (comma resp. right parenthesis) and
1845 The token lists may optionally be enclosed into curly braces. This allows
1846 the inclusion of tokens that would otherwise terminate the list (the closing
1847 right paren in the given case). Often a macro parameter is used for any of
1850 The function compares tokens <em/and/ token values. If you need a function
1851 that just compares the type of tokens, have a look at the <tt><ref
1852 id=".MATCH" name=".MATCH"></tt> function.
1854 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1858 <sect>Control commands<label id="control-commands"><p>
1860 Here's a list of all control commands and a description, what they do:
1863 <sect1><tt>.A16</tt><label id=".A16"><p>
1865 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1867 Note: This command will not emit any code, it will tell the assembler to
1868 create 16 bit operands for immediate accumulator addressing mode.
1870 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1873 <sect1><tt>.A8</tt><label id=".A8"><p>
1875 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1877 Note: This command will not emit any code, it will tell the assembler to
1878 create 8 bit operands for immediate accu addressing mode.
1880 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1883 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1885 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1886 may be used for better readability if the data words are address values. In
1887 65816 mode, the address is forced to be 16 bit wide to fit into the current
1888 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1889 must be followed by a sequence of (not necessarily constant) expressions.
1894 .addr $0D00, $AF13, _Clear
1897 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1901 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1903 Align data to a given boundary. The command expects a constant integer
1904 argument in the range 1 ... 65536, plus an optional second argument
1905 in byte range. If there is a second argument, it is used as fill value,
1906 otherwise the value defined in the linker configuration file is used
1907 (the default for this value is zero).
1909 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1910 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1911 number of bytes, since that would break address calculations within the
1912 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1913 of the alignment, because that allows the number of fill bytes to be
1914 calculated in advance by the assembler. You are therefore required to
1915 specify a matching alignment for the segment in the linker config. The
1916 linker will output a warning if the alignment of the segment is less than
1917 what is necessary to have a correct alignment in the object file.
1925 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1926 commands with different arguments. To allow the assembler to calculate the
1927 number of fill bytes in advance, the alignment of the segment must be a
1928 multiple of each of the alignment factors. This may result in unexpectedly
1929 large alignments for the segment within the module.
1940 For the assembler to be able to align correctly, the segment must be aligned
1941 to the least common multiple of 15 and 18 which is 90. The assembler will
1942 calculate this automatically and will mark the segment with this value.
1944 Unfortunately, the combined alignment may get rather large without the user
1945 knowing about it, wasting space in the final executable. If we add another
1946 alignment to the example above
1957 the assembler will force a segment alignment to the least common multiple of
1958 15, 18 and 251 - which is 22590. To protect the user against errors, the
1959 assembler will issue a warning when the combined alignment exceeds 256. The
1960 command line option <tt><ref id="option--large-alignment"
1961 name="--large-alignment"></tt> will disable this warning.
1963 Please note that with alignments that are a power of two (which were the
1964 only alignments possible in older versions of the assembler), the problem is
1965 less severe, because the least common multiple of powers to the same base is
1966 always the larger one.
1970 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1972 Define a string with a trailing zero.
1977 Msg: .asciiz "Hello world"
1980 This will put the string "Hello world" followed by a binary zero into
1981 the current segment. There may be more strings separated by commas, but
1982 the binary zero is only appended once (after the last one).
1985 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1987 Add an assertion. The command is followed by an expression, an action
1988 specifier, and an optional message that is output in case the assertion
1989 fails. If no message was given, the string "Assertion failed" is used. The
1990 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
1991 <tt/lderror/. In the former two cases, the assertion is evaluated by the
1992 assembler if possible, and in any case, it's also passed to the linker in
1993 the object file (if one is generated). The linker will then evaluate the
1994 expression when segment placement has been done.
1999 .assert * = $8000, error, "Code not at $8000"
2002 The example assertion will check that the current location is at $8000,
2003 when the output file is written, and abort with an error if this is not
2004 the case. More complex expressions are possible. The action specifier
2005 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2006 an error message. In the latter case, generation of the output file is
2007 suppressed in both the assembler and linker.
2010 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2012 Is followed by a plus or a minus character. When switched on (using a
2013 +), undefined symbols are automatically marked as import instead of
2014 giving errors. When switched off (which is the default so this does not
2015 make much sense), this does not happen and an error message is
2016 displayed. The state of the autoimport flag is evaluated when the
2017 complete source was translated, before outputting actual code, so it is
2018 <em/not/ possible to switch this feature on or off for separate sections
2019 of code. The last setting is used for all symbols.
2021 You should probably not use this switch because it delays error
2022 messages about undefined symbols until the link stage. The cc65
2023 compiler (which is supposed to produce correct assembler code in all
2024 circumstances, something which is not true for most assembler
2025 programmers) will insert this command to avoid importing each and every
2026 routine from the runtime library.
2031 .autoimport + ; Switch on auto import
2034 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2036 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2037 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2038 the operator '^' prepended to each expression in its list.
2043 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2045 TableLookupLo: .lobytes MyTable
2046 TableLookupHi: .hibytes MyTable
2047 TableLookupBank: .bankbytes MyTable
2050 which is equivalent to
2053 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2054 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2055 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2058 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2059 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2060 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2063 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2065 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2066 so this is a shortcut for
2072 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2075 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2077 Define byte sized data. Must be followed by a sequence of (byte ranged)
2078 expressions or strings.
2084 .byt "world", $0D, $00
2088 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2090 Switch on or off case sensitivity on identifiers. The default is off
2091 (that is, identifiers are case sensitive), but may be changed by the
2092 -i switch on the command line.
2093 The command must be followed by a '+' or '-' character to switch the
2094 option on or off respectively.
2099 .case - ; Identifiers are not case sensitive
2103 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2105 Apply a custom mapping for characters. The command is followed by two
2106 numbers in the range 1..255. The first one is the index of the source
2107 character, the second one is the mapping. The mapping applies to all
2108 character and string constants when they generate output, and overrides
2109 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2110 command line switch.
2115 .charmap $41, $61 ; Map 'A' to 'a'
2119 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2121 Switch to the CODE segment. The name of the CODE segment is always
2122 "CODE", so this is a shortcut for
2128 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2131 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2133 Export a symbol and mark it in a special way. The linker is able to build
2134 tables of all such symbols. This may be used to automatically create a list
2135 of functions needed to initialize linked library modules.
2137 Note: The linker has a feature to build a table of marked routines, but it
2138 is your code that must call these routines, so just declaring a symbol with
2139 <tt/.CONDES/ does nothing by itself.
2141 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2142 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2143 is implied by <tt/.CONDES/.
2145 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2146 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2147 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2148 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2149 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2150 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2151 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2153 After the type, an optional priority may be specified. Higher numeric values
2154 mean higher priority. If no priority is given, the default priority of 7 is
2155 used. Be careful when assigning priorities to your own module constructors
2156 so they won't interfere with the ones in the cc65 library.
2161 .condes ModuleInit, constructor
2162 .condes ModInit, 0, 16
2165 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2166 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2167 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2168 name="Module constructors/destructors"> explaining the feature in more
2172 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2174 Export a symbol and mark it as a module constructor. This may be used
2175 together with the linker to build a table of constructor subroutines that
2176 are called by the startup code.
2178 Note: The linker has a feature to build a table of marked routines, but it
2179 is your code that must call these routines, so just declaring a symbol as
2180 constructor does nothing by itself.
2182 A constructor is always exported as an absolute (16 bit) symbol. You don't
2183 need to use an additional <tt/.export/ statement, this is implied by
2184 <tt/.constructor/. It may have an optional priority that is separated by a
2185 comma. Higher numeric values mean a higher priority. If no priority is
2186 given, the default priority of 7 is used. Be careful when assigning
2187 priorities to your own module constructors so they won't interfere with the
2188 ones in the cc65 library.
2193 .constructor ModuleInit
2194 .constructor ModInit, 16
2197 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2198 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2199 <ref id="condes" name="Module constructors/destructors"> explaining the
2200 feature in more detail.
2203 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2205 Switch to the DATA segment. The name of the DATA segment is always
2206 "DATA", so this is a shortcut for
2212 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2215 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2217 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2218 create word sized data in native 65XX format). Must be followed by a
2219 sequence of (word ranged) expressions.
2227 This will emit the bytes
2233 into the current segment in that order.
2236 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2238 Switch on or off debug info generation. The default is off (that is,
2239 the object file will not contain debug infos), but may be changed by the
2240 -g switch on the command line.
2241 The command must be followed by a '+' or '-' character to switch the
2242 option on or off respectively.
2247 .debuginfo + ; Generate debug info
2251 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2253 Start a define style macro definition. The command is followed by an
2254 identifier (the macro name) and optionally by a list of formal arguments
2257 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2258 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2261 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2262 section <ref id="macros" name="Macros">.
2265 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2267 Delete a classic macro (defined with <tt><ref id=".MACRO"
2268 name=".MACRO"></tt>) . The command is followed by the name of an
2269 existing macro. Its definition will be deleted together with the name.
2270 If necessary, another macro with this name may be defined later.
2272 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2273 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2274 <tt><ref id=".MACRO" name=".MACRO"></tt>
2276 See also section <ref id="macros" name="Macros">.
2279 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2281 Builtin function. The function expects an identifier as argument in braces.
2282 The argument is evaluated, and the function yields "true" if the identifier
2283 is a symbol that is already defined somewhere in the source file up to the
2284 current position. Otherwise the function yields false. As an example, the
2285 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2292 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2294 Export a symbol and mark it as a module destructor. This may be used
2295 together with the linker to build a table of destructor subroutines that
2296 are called by the startup code.
2298 Note: The linker has a feature to build a table of marked routines, but it
2299 is your code that must call these routines, so just declaring a symbol as
2300 constructor does nothing by itself.
2302 A destructor is always exported as an absolute (16 bit) symbol. You don't
2303 need to use an additional <tt/.export/ statement, this is implied by
2304 <tt/.destructor/. It may have an optional priority that is separated by a
2305 comma. Higher numerical values mean a higher priority. If no priority is
2306 given, the default priority of 7 is used. Be careful when assigning
2307 priorities to your own module destructors so they won't interfere with the
2308 ones in the cc65 library.
2313 .destructor ModuleDone
2314 .destructor ModDone, 16
2317 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2318 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2319 section <ref id="condes" name="Module constructors/destructors"> explaining
2320 the feature in more detail.
2323 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2325 Define dword sized data (4 bytes) Must be followed by a sequence of
2331 .dword $12344512, $12FA489
2335 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2337 Conditional assembly: Reverse the current condition.
2340 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2342 Conditional assembly: Reverse current condition and test a new one.
2345 <sect1><tt>.END</tt><label id=".END"><p>
2347 Forced end of assembly. Assembly stops at this point, even if the command
2348 is read from an include file.
2351 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2353 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2356 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2358 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2359 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2362 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2364 Marks the end of a macro definition.
2366 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2367 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2368 <tt><ref id=".MACRO" name=".MACRO"></tt>
2370 See also section <ref id="macros" name="Macros">.
2373 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2375 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2378 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2380 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2383 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2385 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2388 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2390 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2391 command and the separate section named <ref id="structs" name=""Structs
2395 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2397 Start an enumeration. This directive is very similar to the C <tt/enum/
2398 keyword. If a name is given, a new scope is created for the enumeration,
2399 otherwise the enumeration members are placed in the enclosing scope.
2401 In the enumeration body, symbols are declared. The first symbol has a value
2402 of zero, and each following symbol will get the value of the preceding plus
2403 one. This behaviour may be overridden by an explicit assignment. Two symbols
2404 may have the same value.
2416 Above example will create a new scope named <tt/errorcodes/ with three
2417 symbols in it that get the values 0, 1 and 2 respectively. Another way
2418 to write this would have been:
2428 Please note that explicit scoping must be used to access the identifiers:
2431 .word errorcodes::no_error
2434 A more complex example:
2443 EWOULDBLOCK = EAGAIN
2447 In this example, the enumeration does not have a name, which means that the
2448 members will be visible in the enclosing scope and can be used in this scope
2449 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2450 The value for the following members is incremented by one, so <tt/EOK/ would
2451 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2452 override for the value using an already defined symbol.
2455 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2457 Force an assembly error. The assembler will output an error message
2458 preceded by "User error". Assembly is continued but no object file will
2461 This command may be used to check for initial conditions that must be
2462 set before assembling a source file.
2472 .error "Must define foo or bar!"
2476 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2477 <tt><ref id=".OUT" name=".OUT"></tt>,
2478 <tt><ref id=".WARNING" name=".WARNING"></tt>
2481 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2483 Abort a macro expansion immediately. This command is often useful in
2486 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2487 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2488 <tt><ref id=".MACRO" name=".MACRO"></tt>
2490 See also section <ref id="macros" name="Macros">.
2493 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2495 Make symbols accessible from other modules. Must be followed by a comma
2496 separated list of symbols to export, with each one optionally followed by an
2497 address specification and (also optional) an assignment. Using an additional
2498 assignment in the export statement allows to define and export a symbol in
2499 one statement. The default is to export the symbol with the address size it
2500 actually has. The assembler will issue a warning, if the symbol is exported
2501 with an address size smaller than the actual address size.
2508 .export foobar: far = foo * bar
2509 .export baz := foobar, zap: far = baz - bar
2512 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2515 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2518 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2520 Make symbols accessible from other modules. Must be followed by a comma
2521 separated list of symbols to export. The exported symbols are explicitly
2522 marked as zero page symbols. An assignment may be included in the
2523 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2530 .exportzp baz := $02
2533 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2536 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2538 Define far (24 bit) address data. The command must be followed by a
2539 sequence of (not necessarily constant) expressions.
2544 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2547 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2550 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2552 Force an assembly error and terminate assembly. The assembler will output an
2553 error message preceded by "User error" and will terminate assembly
2556 This command may be used to check for initial conditions that must be
2557 set before assembling a source file.
2567 .fatal "Must define foo or bar!"
2571 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2572 <tt><ref id=".OUT" name=".OUT"></tt>,
2573 <tt><ref id=".WARNING" name=".WARNING"></tt>
2576 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2578 This directive may be used to enable one or more compatibility features
2579 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2580 possible, it may be useful when porting sources written for other
2581 assemblers. There is no way to switch a feature off, once you have
2582 enabled it, so using
2588 will enable the feature until end of assembly is reached.
2590 The following features are available:
2594 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2596 Accept the at character (`@') as a valid character in identifiers. The
2597 at character is not allowed to start an identifier, even with this
2600 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2602 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2603 comment terminators. Note that C comments may not be nested. There's also a
2604 pitfall when using C like comments: All statements must be terminated by
2605 "end-of-line". Using C like comments, it is possible to hide the newline,
2606 which results in error messages. See the following non working example:
2609 lda #$00 /* This comment hides the newline
2613 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2615 Accept the dollar sign (`$') as a valid character in identifiers. The
2616 dollar character is not allowed to start an identifier, even with this
2619 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2621 The dollar sign may be used as an alias for the star (`*'), which
2622 gives the value of the current PC in expressions.
2623 Note: Assignment to the pseudo variable is not allowed.
2625 <tag><tt>force_range</tt><label id="force_range"></tag>
2627 Force expressions into their valid range for immediate addressing and
2628 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2629 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2630 since it will completely disable error checks.
2632 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2634 Allow labels without a trailing colon. These labels are only accepted,
2635 if they start at the beginning of a line (no leading white space).
2637 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2639 Accept the dot (`.') as the first character of an identifier. This may be
2640 used for example to create macro names that start with a dot emulating
2641 control directives of other assemblers. Note however, that none of the
2642 reserved keywords built into the assembler, that starts with a dot, may be
2643 overridden. When using this feature, you may also get into trouble if
2644 later versions of the assembler define new keywords starting with a dot.
2646 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2648 Accept single quotes as well as double quotes as terminators for char
2651 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2653 Accept single quotes as well as double quotes as terminators for string
2656 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2658 Accept single quoted character constants where the terminating quote is
2663 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2664 loose_string_term/, since in this case the input would be ambiguous.
2666 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2668 This feature makes relocatable/absolute mode local to the current segment.
2669 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2670 effect will only enable absolute mode for the current segment. Dito for
2671 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2673 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2675 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2676 is enabled). Such an assignment is handled identical to the <tt><ref
2677 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2678 removing the lines with the assignments may also be an option when porting
2679 code written for older assemblers).
2681 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2683 Allow the use of instructions names as names for macros and symbols. This
2684 makes it possible to "overload" instructions by defining a macro with the
2685 same name. This does also make it possible to introduce hard to find errors
2686 in your code, so be careful!
2690 It is also possible to specify features on the command line using the
2691 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2692 This is useful when translating sources written for older assemblers, when
2693 you don't want to change the source code.
2695 As an example, to translate sources written for Andre Fachats xa65
2696 assembler, the features
2699 labels_without_colons, pc_assignment, loose_char_term
2702 may be helpful. They do not make ca65 completely compatible, so you may not
2703 be able to translate the sources without changes, even when enabling these
2704 features. However, I have found several sources that translate without
2705 problems when enabling these features on the command line.
2708 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2710 Insert an option string into the object file. There are two forms of
2711 this command, one specifies the option by a keyword, the second
2712 specifies it as a number. Since usage of the second one needs knowledge
2713 of the internal encoding, its use is not recommended and I will only
2714 describe the first form here.
2716 The command is followed by one of the keywords
2724 a comma and a string. The option is written into the object file
2725 together with the string value. This is currently unidirectional and
2726 there is no way to actually use these options once they are in the
2732 .fileopt comment, "Code stolen from my brother"
2733 .fileopt compiler, "BASIC 2.0"
2734 .fopt author, "J. R. User"
2738 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2740 Import an absolute symbol from another module. The command is followed by a
2741 comma separated list of symbols to import. The command is similar to <tt>
2742 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2743 written to the generated object file, even if the symbol is never referenced
2744 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2745 references for unused symbols).
2750 .forceimport needthisone, needthistoo
2753 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2756 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2758 Declare symbols as global. Must be followed by a comma separated list of
2759 symbols to declare. Symbols from the list, that are defined somewhere in the
2760 source, are exported, all others are imported. Additional <tt><ref
2761 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2762 name=".EXPORT"></tt> commands for the same symbol are allowed.
2771 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2773 Declare symbols as global. Must be followed by a comma separated list of
2774 symbols to declare. Symbols from the list, that are defined somewhere in the
2775 source, are exported, all others are imported. Additional <tt><ref
2776 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2777 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2778 in the list are explicitly marked as zero page symbols.
2786 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2788 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2789 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2790 the operator '>' prepended to each expression in its list.
2795 .lobytes $1234, $2345, $3456, $4567
2796 .hibytes $fedc, $edcb, $dcba, $cba9
2799 which is equivalent to
2802 .byte $34, $45, $56, $67
2803 .byte $fe, $ed, $dc, $cb
2809 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2811 TableLookupLo: .lobytes MyTable
2812 TableLookupHi: .hibytes MyTable
2815 which is equivalent to
2818 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2819 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2822 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2823 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2824 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2827 <sect1><tt>.I16</tt><label id=".I16"><p>
2829 Valid only in 65816 mode. Switch the index registers to 16 bit.
2831 Note: This command will not emit any code, it will tell the assembler to
2832 create 16 bit operands for immediate operands.
2834 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2835 name=".SMART"></tt> commands.
2838 <sect1><tt>.I8</tt><label id=".I8"><p>
2840 Valid only in 65816 mode. Switch the index registers to 8 bit.
2842 Note: This command will not emit any code, it will tell the assembler to
2843 create 8 bit operands for immediate operands.
2845 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2846 name=".SMART"></tt> commands.
2849 <sect1><tt>.IF</tt><label id=".IF"><p>
2851 Conditional assembly: Evaluate an expression and switch assembler output
2852 on or off depending on the expression. The expression must be a constant
2853 expression, that is, all operands must be defined.
2855 A expression value of zero evaluates to FALSE, any other value evaluates
2859 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2861 Conditional assembly: Check if there are any remaining tokens in this line,
2862 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2863 condition is not true, further lines are not assembled until an <tt><ref
2864 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2865 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2867 This command is often used to check if a macro parameter was given. Since an
2868 empty macro parameter will evaluate to nothing, the condition will evaluate
2869 to FALSE if an empty parameter was given.
2883 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2886 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2888 Conditional assembly: Evaluate an expression and switch assembler output
2889 on or off depending on the constness of the expression.
2891 A const expression evaluates to to TRUE, a non const expression (one
2892 containing an imported or currently undefined symbol) evaluates to
2895 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2898 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2900 Conditional assembly: Check if a symbol is defined. Must be followed by
2901 a symbol name. The condition is true if the the given symbol is already
2902 defined, and false otherwise.
2904 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2907 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2909 Conditional assembly: Check if there are any remaining tokens in this line,
2910 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2911 condition is not true, further lines are not assembled until an <tt><ref
2912 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2913 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2915 This command is often used to check if a macro parameter was given.
2916 Since an empty macro parameter will evaluate to nothing, the condition
2917 will evaluate to FALSE if an empty parameter was given.
2930 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2933 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2935 Conditional assembly: Check if a symbol is defined. Must be followed by
2936 a symbol name. The condition is true if the the given symbol is not
2937 defined, and false otherwise.
2939 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2942 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2944 Conditional assembly: Check if a symbol is referenced. Must be followed
2945 by a symbol name. The condition is true if if the the given symbol was
2946 not referenced before, and false otherwise.
2948 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2951 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2953 Conditional assembly: Check if the assembler is currently in 6502 mode
2954 (see <tt><ref id=".P02" name=".P02"></tt> command).
2957 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2959 Conditional assembly: Check if the assembler is currently in 65816 mode
2960 (see <tt><ref id=".P816" name=".P816"></tt> command).
2963 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2965 Conditional assembly: Check if the assembler is currently in 65C02 mode
2966 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2969 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2971 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2972 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2975 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2977 Conditional assembly: Check if a symbol is referenced. Must be followed
2978 by a symbol name. The condition is true if if the the given symbol was
2979 referenced before, and false otherwise.
2981 This command may be used to build subroutine libraries in include files
2982 (you may use separate object modules for this purpose too).
2987 .ifref ToHex ; If someone used this subroutine
2988 ToHex: tay ; Define subroutine
2994 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2997 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2999 Import a symbol from another module. The command is followed by a comma
3000 separated list of symbols to import, with each one optionally followed by
3001 an address specification.
3007 .import bar: zeropage
3010 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3013 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3015 Import a symbol from another module. The command is followed by a comma
3016 separated list of symbols to import. The symbols are explicitly imported
3017 as zero page symbols (that is, symbols with values in byte range).
3025 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3028 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3030 Include a file as binary data. The command expects a string argument
3031 that is the name of a file to include literally in the current segment.
3032 In addition to that, a start offset and a size value may be specified,
3033 separated by commas. If no size is specified, all of the file from the
3034 start offset to end-of-file is used. If no start position is specified
3035 either, zero is assumed (which means that the whole file is inserted).
3040 ; Include whole file
3041 .incbin "sprites.dat"
3043 ; Include file starting at offset 256
3044 .incbin "music.dat", $100
3046 ; Read 100 bytes starting at offset 200
3047 .incbin "graphics.dat", 200, 100
3051 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3053 Include another file. Include files may be nested up to a depth of 16.
3062 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3064 Export a symbol and mark it as an interruptor. This may be used together
3065 with the linker to build a table of interruptor subroutines that are called
3068 Note: The linker has a feature to build a table of marked routines, but it
3069 is your code that must call these routines, so just declaring a symbol as
3070 interruptor does nothing by itself.
3072 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3073 need to use an additional <tt/.export/ statement, this is implied by
3074 <tt/.interruptor/. It may have an optional priority that is separated by a
3075 comma. Higher numeric values mean a higher priority. If no priority is
3076 given, the default priority of 7 is used. Be careful when assigning
3077 priorities to your own module constructors so they won't interfere with the
3078 ones in the cc65 library.
3083 .interruptor IrqHandler
3084 .interruptor Handler, 16
3087 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3088 section <ref id="condes" name="Module constructors/destructors"> explaining
3089 the feature in more detail.
3092 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3094 Switch on or off line continuations using the backslash character
3095 before a newline. The option is off by default.
3096 Note: Line continuations do not work in a comment. A backslash at the
3097 end of a comment is treated as part of the comment and does not trigger
3099 The command must be followed by a '+' or '-' character to switch the
3100 option on or off respectively.
3105 .linecont + ; Allow line continuations
3108 #$20 ; This is legal now
3112 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3114 Enable output to the listing. The command must be followed by a boolean
3115 switch ("on", "off", "+" or "-") and will enable or disable listing
3117 The option has no effect if the listing is not enabled by the command line
3118 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3119 to the listing file, if the counter is greater than zero, and suppressed if
3120 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3126 .list on ; Enable listing output
3130 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3132 Set, how many bytes are shown in the listing for one source line. The
3133 default is 12, so the listing will show only the first 12 bytes for any
3134 source line that generates more than 12 bytes of code or data.
3135 The directive needs an argument, which is either "unlimited", or an
3136 integer constant in the range 4..255.
3141 .listbytes unlimited ; List all bytes
3142 .listbytes 12 ; List the first 12 bytes
3143 .incbin "data.bin" ; Include large binary file
3147 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3149 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3150 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3151 the operator '<' prepended to each expression in its list.
3156 .lobytes $1234, $2345, $3456, $4567
3157 .hibytes $fedc, $edcb, $dcba, $cba9
3160 which is equivalent to
3163 .byte $34, $45, $56, $67
3164 .byte $fe, $ed, $dc, $cb
3170 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3172 TableLookupLo: .lobytes MyTable
3173 TableLookupHi: .hibytes MyTable
3176 which is equivalent to
3179 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3180 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3183 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3184 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3185 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3188 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3190 This command may only be used inside a macro definition. It declares a
3191 list of identifiers as local to the macro expansion.
3193 A problem when using macros are labels: Since they don't change their name,
3194 you get a "duplicate symbol" error if the macro is expanded the second time.
3195 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3196 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3199 Some other assemblers start a new lexical block inside a macro expansion.
3200 This has some drawbacks however, since that will not allow <em/any/ symbol
3201 to be visible outside a macro, a feature that is sometimes useful. The
3202 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3203 to address the problem.
3205 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3209 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3211 Defines the character that start "cheap" local labels. You may use one
3212 of '@' and '?' as start character. The default is '@'.
3214 Cheap local labels are labels that are visible only between two non
3215 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3216 using explicit lexical nesting.
3223 Clear: lda #$00 ; Global label
3224 ?Loop: sta Mem,y ; Local label
3228 Sub: ... ; New global label
3229 bne ?Loop ; ERROR: Unknown identifier!
3233 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3235 Insert a predefined macro package. The command is followed by an
3236 identifier specifying the macro package to insert. Available macro
3240 atari Defines the scrcode macro.
3241 cbm Defines the scrcode macro.
3242 cpu Defines constants for the .CPU variable.
3243 generic Defines generic macros like add and sub.
3244 longbranch Defines conditional long jump macros.
3247 Including a macro package twice, or including a macro package that
3248 redefines already existing macros will lead to an error.
3253 .macpack longbranch ; Include macro package
3255 cmp #$20 ; Set condition codes
3256 jne Label ; Jump long on condition
3259 Macro packages are explained in more detail in section <ref
3260 id="macropackages" name="Macro packages">.
3263 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3265 Start a classic macro definition. The command is followed by an identifier
3266 (the macro name) and optionally by a comma separated list of identifiers
3267 that are macro parameters. A macro definition is terminated by <tt><ref
3268 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3273 .macro ldax arg ; Define macro ldax
3278 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3279 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3280 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3282 See also section <ref id="macros" name="Macros">.
3285 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3287 Start a section of absolute code. The command is followed by a constant
3288 expression that gives the new PC counter location for which the code is
3289 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3292 By default, absolute/relocatable mode is global (valid even when switching
3293 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3294 it can be made segment local.
3296 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3297 code at a specific address is the job of the linker, not the assembler, so
3298 there is usually no reason to assemble code to a specific address.
3303 .org $7FF ; Emit code starting at $7FF
3307 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3309 Output a string to the console without producing an error. This command
3310 is similar to <tt/.ERROR/, however, it does not force an assembler error
3311 that prevents the creation of an object file.
3316 .out "This code was written by the codebuster(tm)"
3319 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3320 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3321 <tt><ref id=".WARNING" name=".WARNING"></tt>
3324 <sect1><tt>.P02</tt><label id=".P02"><p>
3326 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3327 instructions. This is the default if not overridden by the
3328 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3330 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3331 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3334 <sect1><tt>.P816</tt><label id=".P816"><p>
3336 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3337 6502 instruction sets.
3339 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3340 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3343 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3345 Set the page length for the listing. Must be followed by an integer
3346 constant. The value may be "unlimited", or in the range 32 to 127. The
3347 statement has no effect if no listing is generated. The default value is -1
3348 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3349 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3350 after assembly is complete, you cannot use multiple line lengths with one
3351 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3356 .pagelength 66 ; Use 66 lines per listing page
3358 .pagelength unlimited ; Unlimited page length
3362 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3364 Enable the 65C02 instructions set. This instruction set includes all
3365 6502 and 65SC02 instructions.
3367 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3368 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3371 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3373 Pop the last CPU setting from the stack, and activate it.
3375 This command will switch back to the CPU that was last pushed onto the CPU
3376 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3377 remove this entry from the stack.
3379 The assembler will print an error message if the CPU stack is empty when
3380 this command is issued.
3382 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3383 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3386 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3388 Pop the last pushed segment from the stack, and set it.
3390 This command will switch back to the segment that was last pushed onto the
3391 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3392 command, and remove this entry from the stack.
3394 The assembler will print an error message if the segment stack is empty
3395 when this command is issued.
3397 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3400 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3402 Start a nested lexical level with the given name and adds a symbol with this
3403 name to the enclosing scope. All new symbols from now on are in the local
3404 lexical level and are accessible from outside only via <ref id="scopesyntax"
3405 name="explicit scope specification">. Symbols defined outside this local
3406 level may be accessed as long as their names are not used for new symbols
3407 inside the level. Symbols names in other lexical levels do not clash, so you
3408 may use the same names for identifiers. The lexical level ends when the
3409 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3410 may be nested up to a depth of 16 (this is an artificial limit to protect
3411 against errors in the source).
3413 Note: Macro names are always in the global level and in a separate name
3414 space. There is no special reason for this, it's just that I've never
3415 had any need for local macro definitions.
3420 .proc Clear ; Define Clear subroutine, start new level
3422 L1: sta Mem,y ; L1 is local and does not cause a
3423 ; duplicate symbol error if used in other
3426 bne L1 ; Reference local symbol
3428 .endproc ; Leave lexical level
3431 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3435 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3437 Enable the 65SC02 instructions set. This instruction set includes all
3440 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3441 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3444 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3446 Push the currently active CPU onto a stack. The stack has a size of 8
3449 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3450 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3451 later, without knowledge of the current CPU setting.
3453 The assembler will print an error message if the CPU stack is already full,
3454 when this command is issued.
3456 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3457 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3460 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3462 Push the currently active segment onto a stack. The entries on the stack
3463 include the name of the segment and the segment type. The stack has a size
3466 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3467 to switch to another segment and to restore the old segment later, without
3468 even knowing the name and type of the current segment.
3470 The assembler will print an error message if the segment stack is already
3471 full, when this command is issued.
3473 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3476 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3478 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3479 name=".ORG"></tt> command.
3482 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3484 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3485 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3486 a constant expression that tells how many times the commands in the body
3487 should get repeated. Optionally, a comma and an identifier may be specified.
3488 If this identifier is found in the body of the repeat statement, it is
3489 replaced by the current repeat count (starting with zero for the first time
3490 the body is repeated).
3492 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3493 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3494 level will be used, not the one from the outer level.
3498 The following macro will emit a string that is "encrypted" in that all
3499 characters of the string are XORed by the value $55.
3503 .repeat .strlen(Arg), I
3504 .byte .strat(Arg, I) ^ $55
3509 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3512 <sect1><tt>.RES</tt><label id=".RES"><p>
3514 Reserve storage. The command is followed by one or two constant
3515 expressions. The first one is mandatory and defines, how many bytes of
3516 storage should be defined. The second, optional expression must by a
3517 constant byte value that will be used as value of the data. If there
3518 is no fill value given, the linker will use the value defined in the
3519 linker configuration file (default: zero).
3524 ; Reserve 12 bytes of memory with value $AA
3529 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3531 Switch to the RODATA segment. The name of the RODATA segment is always
3532 "RODATA", so this is a shortcut for
3538 The RODATA segment is a segment that is used by the compiler for
3539 readonly data like string constants.
3541 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3544 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3546 Start a nested lexical level with the given name. All new symbols from now
3547 on are in the local lexical level and are accessible from outside only via
3548 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3549 outside this local level may be accessed as long as their names are not used
3550 for new symbols inside the level. Symbols names in other lexical levels do
3551 not clash, so you may use the same names for identifiers. The lexical level
3552 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3553 read. Lexical levels may be nested up to a depth of 16 (this is an
3554 artificial limit to protect against errors in the source).
3556 Note: Macro names are always in the global level and in a separate name
3557 space. There is no special reason for this, it's just that I've never
3558 had any need for local macro definitions.
3563 .scope Error ; Start new scope named Error
3565 File = 1 ; File error
3566 Parse = 2 ; Parse error
3567 .endscope ; Close lexical level
3570 lda #Error::File ; Use symbol from scope Error
3573 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3577 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3579 Switch to another segment. Code and data is always emitted into a
3580 segment, that is, a named section of data. The default segment is
3581 "CODE". There may be up to 254 different segments per object file
3582 (and up to 65534 per executable). There are shortcut commands for
3583 the most common segments ("CODE", "DATA" and "BSS").
3585 The command is followed by a string containing the segment name (there are
3586 some constraints for the name - as a rule of thumb use only those segment
3587 names that would also be valid identifiers). There may also be an optional
3588 address size separated by a colon. See the section covering <tt/<ref
3589 id="address-sizes" name="address sizes">/ for more information.
3591 The default address size for a segment depends on the memory model specified
3592 on the command line. The default is "absolute", which means that you don't
3593 have to use an address size modifier in most cases.
3595 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3596 That is, the segment will reside somewhere in core memory outside the zero
3597 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3598 page and direct (short) addressing is possible for data in this segment.
3600 Beware: Only labels in a segment with the zeropage attribute are marked
3601 as reachable by short addressing. The `*' (PC counter) operator will
3602 work as in other segments and will create absolute variable values.
3604 Please note that a segment cannot have two different address sizes. A
3605 segment specified as zeropage cannot be declared as being absolute later.
3610 .segment "ROM2" ; Switch to ROM2 segment
3611 .segment "ZP2": zeropage ; New direct segment
3612 .segment "ZP2" ; Ok, will use last attribute
3613 .segment "ZP2": absolute ; Error, redecl mismatch
3616 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3617 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3618 id=".RODATA" name=".RODATA"></tt>
3621 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3623 Switch the CPU instruction set. The command is followed by a string that
3624 specifies the CPU. Possible values are those that can also be supplied to
3625 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3626 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3627 note that support for the sunplus CPU is not available in the freeware
3628 version, because the instruction set of the sunplus CPU is "proprietary
3631 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3632 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3633 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3634 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3635 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3636 <tt><ref id=".P02" name=".P02"></tt>,
3637 <tt><ref id=".P816" name=".P816"></tt>,
3638 <tt><ref id=".PC02" name=".PC02"></tt>,
3639 <tt><ref id=".PSC02" name=".PSC02"></tt>
3642 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3644 Switch on or off smart mode. The command must be followed by a '+' or '-'
3645 character to switch the option on or off respectively. The default is off
3646 (that is, the assembler doesn't try to be smart), but this default may be
3647 changed by the -s switch on the command line.
3649 In smart mode the assembler will do the following:
3652 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3653 and update the operand sizes accordingly. If the operand of such an
3654 instruction cannot be evaluated by the assembler (for example, because
3655 the operand is an imported symbol), a warning is issued. Beware: Since
3656 the assembler cannot trace the execution flow this may lead to false
3657 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3658 instructions to tell the assembler about the current settings.
3659 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3660 used within a procedure declared as <tt/far/, or if the procedure has
3661 no explicit address specification, but it is <tt/far/ because of the
3669 .smart - ; Stop being smart
3672 See: <tt><ref id=".A16" name=".A16"></tt>,
3673 <tt><ref id=".A8" name=".A8"></tt>,
3674 <tt><ref id=".I16" name=".I16"></tt>,
3675 <tt><ref id=".I8" name=".I8"></tt>
3678 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3680 Starts a struct definition. Structs are covered in a separate section named
3681 <ref id="structs" name=""Structs and unions"">.
3683 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3686 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3688 Enable the SunPlus instructions set. This command will not work in the
3689 freeware version of the assembler, because the instruction set is
3690 "proprietary and confidential".
3692 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3693 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3694 <tt><ref id=".P816" name=".P816"></tt>
3697 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3699 Allocate space for a struct or union.
3710 .tag Point ; Allocate 4 bytes
3714 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3716 Delete a define style macro definition. The command is followed by an
3717 identifier which specifies the name of the macro to delete. Macro
3718 replacement is switched of when reading the token following the command
3719 (otherwise the macro name would be replaced by its replacement list).
3721 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3722 section <ref id="macros" name="Macros">.
3725 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3727 Force an assembly warning. The assembler will output a warning message
3728 preceded by "User warning". This warning will always be output, even if
3729 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3730 command line option.
3732 This command may be used to output possible problems when assembling
3741 .warning "Forward jump in jne, cannot optimize!"
3751 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>
3752 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3753 <tt><ref id=".OUT" name=".OUT"></tt>
3756 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3758 Define word sized data. Must be followed by a sequence of (word ranged,
3759 but not necessarily constant) expressions.
3764 .word $0D00, $AF13, _Clear
3768 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3770 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3771 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3775 .segment "ZEROPAGE", zeropage
3778 Because of the "zeropage" attribute, labels declared in this segment are
3779 addressed using direct addressing mode if possible. You <em/must/ instruct
3780 the linker to place this segment somewhere in the address range 0..$FF
3781 otherwise you will get errors.
3783 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3787 <sect>Macros<label id="macros"><p>
3790 <sect1>Introduction<p>
3792 Macros may be thought of as "parametrized super instructions". Macros are
3793 sequences of tokens that have a name. If that name is used in the source
3794 file, the macro is "expanded", that is, it is replaced by the tokens that
3795 were specified when the macro was defined.
3798 <sect1>Macros without parameters<p>
3800 In its simplest form, a macro does not have parameters. Here's an
3804 .macro asr ; Arithmetic shift right
3805 cmp #$80 ; Put bit 7 into carry
3806 ror ; Rotate right with carry
3810 The macro above consists of two real instructions, that are inserted into
3811 the code, whenever the macro is expanded. Macro expansion is simply done
3812 by using the name, like this:
3821 <sect1>Parametrized macros<p>
3823 When using macro parameters, macros can be even more useful:
3837 When calling the macro, you may give a parameter, and each occurrence of
3838 the name "addr" in the macro definition will be replaced by the given
3857 A macro may have more than one parameter, in this case, the parameters
3858 are separated by commas. You are free to give less parameters than the
3859 macro actually takes in the definition. You may also leave intermediate
3860 parameters empty. Empty parameters are replaced by empty space (that is,
3861 they are removed when the macro is expanded). If you have a look at our
3862 macro definition above, you will see, that replacing the "addr" parameter
3863 by nothing will lead to wrong code in most lines. To help you, writing
3864 macros with a variable parameter list, there are some control commands:
3866 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3867 returns true, if there are any tokens on the remainder of the line. Since
3868 empty parameters are replaced by nothing, this may be used to test if a given
3869 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3872 Look at this example:
3875 .macro ldaxy a, x, y
3888 This macro may be called as follows:
3891 ldaxy 1, 2, 3 ; Load all three registers
3893 ldaxy 1, , 3 ; Load only a and y
3895 ldaxy , , 3 ; Load y only
3898 There's another helper command for determining, which macro parameters are
3899 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3900 replaced by the parameter count given, <em/including/ intermediate empty macro
3904 ldaxy 1 ; .PARAMCOUNT = 1
3905 ldaxy 1,,3 ; .PARAMCOUNT = 3
3906 ldaxy 1,2 ; .PARAMCOUNT = 2
3907 ldaxy 1, ; .PARAMCOUNT = 2
3908 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3911 Macro parameters may optionally be enclosed into curly braces. This allows the
3912 inclusion of tokens that would otherwise terminate the parameter (the comma in
3913 case of a macro parameter).
3916 .macro foo arg1, arg2
3920 foo ($00,x) ; Two parameters passed
3921 foo {($00,x)} ; One parameter passed
3924 In the first case, the macro is called with two parameters: '<tt/($00/'
3925 and 'x)'. The comma is not passed to the macro, since it is part of the
3926 calling sequence, not the parameters.
3928 In the second case, '($00,x)' is passed to the macro, this time
3929 including the comma.
3932 <sect1>Detecting parameter types<p>
3934 Sometimes it is nice to write a macro that acts differently depending on the
3935 type of the argument supplied. An example would be a macro that loads a 16 bit
3936 value from either an immediate operand, or from memory. The <tt/<ref
3937 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3938 functions will allow you to do exactly this:
3942 .if (.match (.left (1, {arg}), #))
3944 lda #<(.right (.tcount ({arg})-1, {arg}))
3945 ldx #>(.right (.tcount ({arg})-1, {arg}))
3947 ; assume absolute or zero page
3954 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3955 check if its argument begins with a hash mark. If so, two immediate loads are
3956 emitted, Otherwise a load from an absolute zero page memory location is
3957 assumed. Please note how the curly braces are used to enclose parameters to
3958 pseudo functions handling token lists. This is necessary, because the token
3959 lists may include commas or parens, which would be treated by the assembler
3962 The macro can be used as
3967 ldax #$1234 ; X=$12, A=$34
3969 ldax foo ; X=$56, A=$78
3973 <sect1>Recursive macros<p>
3975 Macros may be used recursively:
3978 .macro push r1, r2, r3
3987 There's also a special macro to help writing recursive macros: <tt><ref
3988 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3992 .macro push r1, r2, r3, r4, r5, r6, r7
3994 ; First parameter is empty
4000 push r2, r3, r4, r5, r6, r7
4004 When expanding this macro, the expansion will push all given parameters
4005 until an empty one is encountered. The macro may be called like this:
4008 push $20, $21, $32 ; Push 3 ZP locations
4009 push $21 ; Push one ZP location
4013 <sect1>Local symbols inside macros<p>
4015 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4016 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4017 Have a look at the inc16 macro above. Here is it again:
4031 If you have a closer look at the code, you will notice, that it could be
4032 written more efficiently, like this:
4043 But imagine what happens, if you use this macro twice? Since the label
4044 "Skip" has the same name both times, you get a "duplicate symbol" error.
4045 Without a way to circumvent this problem, macros are not as useful, as
4046 they could be. One solution is, to start a new lexical block inside the
4060 Now the label is local to the block and not visible outside. However,
4061 sometimes you want a label inside the macro to be visible outside. To make
4062 that possible, there's a new command that's only usable inside a macro
4063 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
4064 or more symbols as local to the macro expansion. The names of local variables
4065 are replaced by a unique name in each separate macro expansion. So we could
4066 also solve the problem above by using <tt/.LOCAL/:
4070 .local Skip ; Make Skip a local symbol
4077 Skip: ; Not visible outside
4082 <sect1>C style macros<p>
4084 Starting with version 2.5 of the assembler, there is a second macro type
4085 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4086 similar to the classic macro type described above, but behaviour is sometimes
4091 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4092 span more than a line. You may use line continuation (see <tt><ref
4093 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4094 more than one line for increased readability, but the macro itself
4095 may not contain an end-of-line token.
4097 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4098 the name space with classic macros, but they are detected and replaced
4099 at the scanner level. While classic macros may be used in every place,
4100 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4101 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4102 they are more versatile in some situations.
4104 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4105 parameters. While classic macros may have empty parameters, this is
4106 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4107 For this macro type, the number of actual parameters must match
4108 exactly the number of formal parameters.
4110 To make this possible, formal parameters are enclosed in braces when
4111 defining the macro. If there are no parameters, the empty braces may
4114 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4115 contain end-of-line tokens, there are things that cannot be done. They
4116 may not contain several processor instructions for example. So, while
4117 some things may be done with both macro types, each type has special
4118 usages. The types complement each other.
4122 Let's look at a few examples to make the advantages and disadvantages
4125 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4126 following <tt/.DEFINE/:
4131 foo EQU $1234 ; This is accepted now
4134 You may use the directive to define string constants used elsewhere:
4137 ; Define the version number
4138 .define VERSION "12.3a"
4144 Macros with parameters may also be useful:
4147 .define DEBUG(message) .out message
4149 DEBUG "Assembling include file #3"
4152 Note that, while formal parameters have to be placed in braces, this is
4153 not true for the actual parameters. Beware: Since the assembler cannot
4154 detect the end of one parameter, only the first token is used. If you
4155 don't like that, use classic macros instead:
4163 (This is an example where a problem can be solved with both macro types).
4166 <sect1>Characters in macros<p>
4168 When using the <ref id="option-t" name="-t"> option, characters are translated
4169 into the target character set of the specific machine. However, this happens
4170 as late as possible. This means that strings are translated if they are part
4171 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4172 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4173 used as part of an expression.
4175 This behaviour is very intuitive outside of macros but may be confusing when
4176 doing more complex macros. If you compare characters against numeric values,
4177 be sure to take the translation into account.
4180 <sect1>Deleting macros<p>
4182 Macros can be deleted. This will not work if the macro that should be deleted
4183 is currently expanded as in the following non working example:
4187 .delmacro notworking
4190 notworking ; Will not work
4193 The commands to delete classic and define style macros differ. Classic macros
4194 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4195 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4196 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4204 .byte value ; Emit one byte with value 1
4205 mac ; Emit another byte with value 2
4210 .byte value ; Error: Unknown identifier
4211 mac ; Error: Missing ":"
4214 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4215 the name of such a macro is replaced by its replacement list on a very low
4216 level. To get the actual name, macro replacement has to be switched off when
4217 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4218 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4219 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4220 different commands increases flexibility.
4223 <sect>Macro packages<label id="macropackages"><p>
4225 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4226 macro packages may be included with just one command. Available macro packages
4230 <sect1><tt>.MACPACK generic</tt><p>
4232 This macro package defines macros that are useful in almost any program.
4233 Currently defined macros are:
4268 <sect1><tt>.MACPACK longbranch</tt><p>
4270 This macro package defines long conditional jumps. They are named like the
4271 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4272 definition for the "<tt/jeq/" macro, the other macros are built using the same
4277 .if .def(Target) .and ((*+2)-(Target) <= 127)
4286 All macros expand to a short branch, if the label is already defined (back
4287 jump) and is reachable with a short jump. Otherwise the macro expands to a
4288 conditional branch with the branch condition inverted, followed by an absolute
4289 jump to the actual branch target.
4291 The package defines the following macros:
4294 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4299 <sect1><tt>.MACPACK atari</tt><p>
4301 The atari macro package will define a macro named <tt/scrcode/. It takes a
4302 string as argument and places this string into memory translated into screen
4306 <sect1><tt>.MACPACK cbm</tt><p>
4308 The cbm macro package will define a macro named <tt/scrcode/. It takes a
4309 string as argument and places this string into memory translated into screen
4313 <sect1><tt>.MACPACK cpu</tt><p>
4315 This macro package does not define any macros but constants used to examine
4316 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4317 each supported CPU a constant similar to
4329 is defined. These constants may be used to determine the exact type of the
4330 currently enabled CPU. In addition to that, for each CPU instruction set,
4331 another constant is defined:
4343 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4344 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4345 currently enabled CPU supports a specific instruction set. For example the
4346 65C02 supports all instructions of the 65SC02 CPU, so it has the
4347 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4351 .if (.cpu .bitand CPU_ISET_65SC02)
4359 it is possible to determine if the
4365 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4366 CPUs (the latter two are upwards compatible to the 65SC02).
4370 <sect>Predefined constants<label id="predefined-constants"><p>
4372 For better orthogonality, the assembler defines similar symbols as the
4373 compiler, depending on the target system selected:
4376 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
4377 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4378 <item><tt/__ATARI__/ - Target system is <tt/atari/
4379 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4380 <item><tt/__BBC__/ - Target system is <tt/bbc/
4381 <item><tt/__C128__/ - Target system is <tt/c128/
4382 <item><tt/__C16__/ - Target system is <tt/c16/
4383 <item><tt/__C64__/ - Target system is <tt/c64/
4384 <item><tt/__CBM__/ - Target is a Commodore system
4385 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4386 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4387 <item><tt/__GEOS__/ - Target system is <tt/geos/
4388 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4389 <item><tt/__NES__/ - Target system is <tt/nes/
4390 <item><tt/__PET__/ - Target system is <tt/pet/
4391 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4392 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4393 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4397 <sect>Structs and unions<label id="structs"><p>
4399 <sect1>Structs and unions Overview<p>
4401 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4402 are to some degree comparable to their C counterparts. Both have a list of
4403 members. Each member allocates storage and may optionally have a name, which,
4404 in case of a struct, is the offset from the beginning and, in case of a union,
4408 <sect1>Declaration<p>
4410 Here is an example for a very simple struct with two members and a total size
4420 A union shares the total space between all its members, its size is the same
4421 as that of the largest member.
4423 A struct or union must not necessarily have a name. If it is anonymous, no
4424 local scope is opened, the identifiers used to name the members are placed
4425 into the current scope instead.
4427 A struct may contain unnamed members and definitions of local structs. The
4428 storage allocators may contain a multiplier, as in the example below:
4433 .word 2 ; Allocate two words
4440 <sect1>The <tt/.TAG/ keyword<p>
4442 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4443 for an already defined struct or unions within another struct:
4457 Space for a struct or union may be allocated using the <ref id=".TAG"
4458 name=".TAG"> directive.
4464 Currently, members are just offsets from the start of the struct or union. To
4465 access a field of a struct, the member offset has to be added to the address
4466 of the struct itself:
4469 lda C+Circle::Radius ; Load circle radius into A
4472 This may change in a future version of the assembler.
4475 <sect1>Limitations<p>
4477 Structs and unions are currently implemented as nested symbol tables (in fact,
4478 they were a by-product of the improved scoping rules). Currently, the
4479 assembler has no idea of types. This means that the <ref id=".TAG"
4480 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4481 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4482 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4483 this structure accessible by using the '::' operator.
4487 <sect>Module constructors/destructors<label id="condes"><p>
4489 <em>Note:</em> This section applies mostly to C programs, so the explanation
4490 below uses examples from the C libraries. However, the feature may also be
4491 useful for assembler programs.
4494 <sect1>Module constructors/destructors Overview<p>
4496 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4497 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4498 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
4499 special way. The linker is able to generate tables with all functions of a
4500 specific type. Such a table will <em>only</em> include symbols from object
4501 files that are linked into a specific executable. This may be used to add
4502 initialization and cleanup code for library modules, or a table of interrupt
4505 The C heap functions are an example where module initialization code is used.
4506 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4507 variables that contain the start and the end of the heap, pointers to the free
4508 list and so on. Since the end of the heap depends on the size and start of the
4509 stack, it must be initialized at runtime. However, initializing these
4510 variables for programs that do not use the heap are a waste of time and
4513 So the central module defines a function that contains initialization code and
4514 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4515 this module is added to an executable by the linker, the initialization
4516 function will be placed into the table of constructors by the linker. The C
4517 startup code will call all constructors before <tt/main/ and all destructors
4518 after <tt/main/, so without any further work, the heap initialization code is
4519 called once the module is linked in.
4521 While it would be possible to add explicit calls to initialization functions
4522 in the startup code, the new approach has several advantages:
4526 If a module is not included, the initialization code is not linked in and not
4527 called. So you don't pay for things you don't need.
4530 Adding another library that needs initialization does not mean that the
4531 startup code has to be changed. Before we had module constructors and
4532 destructors, the startup code for all systems had to be adjusted to call the
4533 new initialization code.
4536 The feature saves memory: Each additional initialization function needs just
4537 two bytes in the table (a pointer to the function).
4542 <sect1>Calling order<p>
4544 The symbols are sorted in increasing priority order by the linker when using
4545 one of the builtin linker configurations, so the functions with lower
4546 priorities come first and are followed by those with higher priorities. The C
4547 library runtime subroutine that walks over the function tables calls the
4548 functions starting from the top of the table - which means that functions with
4549 a high priority are called first.
4551 So when using the C runtime, functions are called with high priority functions
4552 first, followed by low priority functions.
4557 When using these special symbols, please take care of the following:
4562 The linker will only generate function tables, it will not generate code to
4563 call these functions. If you're using the feature in some other than the
4564 existing C environments, you have to write code to call all functions in a
4565 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4566 in the C runtime for an example on how to do this.
4569 The linker will only add addresses of functions that are in modules linked to
4570 the executable. This means that you have to be careful where to place the
4571 condes functions. If initialization or an irq handler is needed for a group of
4572 functions, be sure to place the function into a module that is linked in
4573 regardless of which function is called by the user.
4576 The linker will generate the tables only when requested to do so by the
4577 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4578 be requested separately.
4581 Constructors and destructors may have priorities. These priorities determine
4582 the order of the functions in the table. If your initialization or cleanup code
4583 does depend on other initialization or cleanup code, you have to choose the
4584 priority for the functions accordingly.
4587 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4588 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4589 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4590 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4591 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4592 (interruptor). The linker generates a separate table for each type on request.
4597 <sect>Porting sources from other assemblers<p>
4599 Sometimes it is necessary to port code written for older assemblers to ca65.
4600 In some cases, this can be done without any changes to the source code by
4601 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4602 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4605 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4606 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4607 done by the linker. Most other assemblers generate absolute code, placement is
4608 done within the assembler and there is no external linker.
4610 In general it is not a good idea to write new code using the emulation
4611 features of the assembler, but there may be situations where even this rule is
4616 You need to use some of the ca65 emulation features to simulate the behaviour
4617 of such simple assemblers.
4620 <item>Prepare your sourcecode like this:
4623 ; if you want TASS style labels without colons
4624 .feature labels_without_colons
4626 ; if you want TASS style character constants
4627 ; ("a" instead of the default 'a')
4628 .feature loose_char_term
4630 .word *+2 ; the cbm load address
4635 notice that the two emulation features are mostly useful for porting
4636 sources originally written in/for TASS, they are not needed for the
4637 actual "simple assembler operation" and are not recommended if you are
4638 writing new code from scratch.
4640 <item>Replace all program counter assignments (which are not possible in ca65
4641 by default, and the respective emulation feature works different from what
4642 you'd expect) by another way to skip to memory locations, for example the
4643 <tt><ref id=".RES" name=".RES"></tt> directive.
4647 .res $2000-* ; reserve memory up to $2000
4650 Please note that other than the original TASS, ca65 can never move the program
4651 counter backwards - think of it as if you are assembling to disk with TASS.
4653 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4654 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4655 of <tt/.goto/, everything involving loops must be replaced by
4656 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4658 <item>To assemble code to a different address than it is executed at, use the
4659 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4660 <tt/.offs/-constructs.
4667 .reloc ; back to normal
4670 <item>Then assemble like this:
4673 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4676 Note that you need to use the actual start address minus two, since two bytes
4677 are used for the cbm load address.
4682 <sect>Bugs/Feedback<p>
4684 If you have problems using the assembler, if you find any bugs, or if
4685 you're doing something interesting with the assembler, I would be glad to
4686 hear from you. Feel free to contact me by email
4687 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4693 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4694 Bassewitz. For usage of the binaries and/or sources the following
4695 conditions do apply:
4697 This software is provided 'as-is', without any expressed or implied
4698 warranty. In no event will the authors be held liable for any damages
4699 arising from the use of this software.
4701 Permission is granted to anyone to use this software for any purpose,
4702 including commercial applications, and to alter it and redistribute it
4703 freely, subject to the following restrictions:
4706 <item> The origin of this software must not be misrepresented; you must not
4707 claim that you wrote the original software. If you use this software
4708 in a product, an acknowledgment in the product documentation would be
4709 appreciated but is not required.
4710 <item> Altered source versions must be plainly marked as such, and must not
4711 be misrepresented as being the original software.
4712 <item> This notice may not be removed or altered from any source