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 some
827 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
828 possible to define symbols or constants that may be used elsewhere. Since
829 the macro facility works on a very low level, there is no scoping. On the
830 other side, you may also define string constants this way (this is not
831 possible with the other symbol types).
837 .DEFINE version "SOS V2.3"
839 four = two * two ; Ok
842 .PROC ; Start local scope
843 two = 3 ; Will give "2 = 3" - invalid!
848 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
850 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
851 id="option-g" name="-g"> is given on the command line), global, local and
852 cheap local labels are written to the object file and will be available in the
853 symbol file via the linker. Unnamed labels are not written to the object file,
854 because they don't have a name which would allow to access them.
858 <sect>Scopes<label id="scopes"><p>
860 ca65 implements several sorts of scopes for symbols.
862 <sect1>Global scope<p>
864 All (non cheap local) symbols that are declared outside of any nested scopes
868 <sect1>Cheap locals<p>
870 A special scope is the scope for cheap local symbols. It lasts from one non
871 local symbol to the next one, without any provisions made by the programmer.
872 All other scopes differ in usage but use the same concept internally.
875 <sect1>Generic nested scopes<p>
877 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
878 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
879 The scope can have a name, in which case it is accessible from the outside by
880 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
881 have a name, all symbols created within the scope are local to the scope, and
882 aren't accessible from the outside.
884 A nested scope can access symbols from the local or from enclosing scopes by
885 name without using explicit scope names. In some cases there may be
886 ambiguities, for example if there is a reference to a local symbol that is not
887 yet defined, but a symbol with the same name exists in outer scopes:
899 In the example above, the <tt/lda/ instruction will load the value 3 into the
900 accumulator, because <tt/foo/ is redefined in the scope. However:
912 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
913 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
914 absolute mode is used instead. In fact, the assembler will not use absolute
915 mode by default, but it will search through the enclosing scopes for a symbol
916 with the given name. If one is found, the address size of this symbol is used.
917 This may lead to errors:
929 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
930 instruction, it will search for an already defined symbol <tt/foo/. It will
931 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
932 zeropage symbol. So the assembler will use zeropage addressing mode. If
933 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
934 the address in the <tt/lda/ instruction already translated, but since the new
935 value needs absolute addressing mode, this fails, and an error message "Range
938 Of course the most simple solution for the problem is to move the definition
939 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
940 rare cases when this cannot be done. In these cases, you can use one of the
941 address size override operators:
953 This will cause the <tt/lda/ instruction to be translated using absolute
954 addressing mode, which means changing the symbol reference later does not
958 <sect1>Nested procedures<p>
960 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
961 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
962 name, and a it will introduce a symbol with this name in the enclosing scope.
971 is actually the same as
980 This is the reason why a procedure must have a name. If you want a scope
981 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
983 <bf/Note:/ As you can see from the example above, scopes and symbols live in
984 different namespaces. There can be a symbol named <tt/foo/ and a scope named
985 <tt/foo/ without any conflicts (but see the section titled <ref
986 id="scopesearch" name=""Scope search order"">).
989 <sect1>Structs, unions and enums<p>
991 Structs, unions and enums are explained in a <ref id="structs" name="separate
992 section">, I do only cover them here, because if they are declared with a
993 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
994 name=".SCOPE">/. However, when no name is specified, the behaviour is
995 different: In this case, no new scope will be opened, symbols declared within
996 a struct, union, or enum declaration will then be added to the enclosing scope
1000 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1002 Accessing symbols from other scopes is possible by using an explicit scope
1003 specification, provided that the scope where the symbol lives in has a name.
1004 The namespace token (<tt/::/) is used to access other scopes:
1012 lda foo::bar ; Access foo in scope bar
1015 The only way to deny access to a scope from the outside is to declare a scope
1016 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1018 A special syntax is used to specify the global scope: If a symbol or scope is
1019 preceded by the namespace token, the global scope is searched:
1026 lda #::bar ; Access the global bar (which is 3)
1031 <sect1>Scope search order<label id="scopesearch"><p>
1033 The assembler searches for a scope in a similar way as for a symbol. First, it
1034 looks in the current scope, and then it walks up the enclosing scopes until
1037 However, one important thing to note when using explicit scope syntax is, that
1038 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1039 used without a preceding definition. This means that in the following
1048 lda #foo::bar ; Will load 3, not 2!
1055 the reference to the scope <tt/foo/ will use the global scope, and not the
1056 local one, because the local one is not visible at the point where it is
1059 Things get more complex if a complete chain of scopes is specified:
1070 lda #outer::inner::bar ; 1
1082 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1083 assembler will first search in the local scope for a scope named <tt/outer/.
1084 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1085 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1086 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1087 this scope, the assembler looks for a symbol named <tt/bar/.
1089 Please note that once the anchor scope is found, all following scopes
1090 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1091 assembler will search the scope tree only for the first scope (if it is not
1092 anchored in the root scope). Starting from there on, there is no flexibility,
1093 so if the scope named <tt/outer/ found by the assembler does not contain a
1094 scope named <tt/inner/, this would be an error, even if such a pair does exist
1095 (one level up in global scope).
1097 Ambiguities that may be introduced by this search algorithm may be removed by
1098 anchoring the scope specification in the global scope. In the example above,
1099 if you want to access the "other" symbol <tt/bar/, you would have to write:
1110 lda #::outer::inner::bar ; 2
1123 <sect>Address sizes and memory models<label id="address-sizes"><p>
1125 <sect1>Address sizes<p>
1127 ca65 assigns each segment and each symbol an address size. This is true, even
1128 if the symbol is not used as an address. You may also think of a value range
1129 of the symbol instead of an address size.
1131 Possible address sizes are:
1134 <item>Zeropage or direct (8 bits)
1135 <item>Absolute (16 bits)
1137 <item>Long (32 bits)
1140 Since the assembler uses default address sizes for the segments and symbols,
1141 it is usually not necessary to override the default behaviour. In cases, where
1142 it is necessary, the following keywords may be used to specify address sizes:
1145 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1146 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1147 <item>FAR for far addressing (24 bits).
1148 <item>LONG or DWORD for long addressing (32 bits).
1152 <sect1>Address sizes of segments<p>
1154 The assembler assigns an address size to each segment. Since the
1155 representation of a label within this segment is "segment start + offset",
1156 labels will inherit the address size of the segment they are declared in.
1158 The address size of a segment may be changed, by using an optional address
1159 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1160 an explanation on how this is done.
1163 <sect1>Address sizes of symbols<p>
1168 <sect1>Memory models<p>
1170 The default address size of a segment depends on the memory model used. Since
1171 labels inherit the address size from the segment they are declared in,
1172 changing the memory model is an easy way to change the address size of many
1178 <sect>Pseudo variables<label id="pseudo-variables"><p>
1180 Pseudo variables are readable in all cases, and in some special cases also
1183 <sect1><tt>*</tt><p>
1185 Reading this pseudo variable will return the program counter at the start
1186 of the current input line.
1188 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1189 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1190 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1193 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1195 Reading this pseudo variable will give a constant integer value that
1196 tells which CPU is currently enabled. It can also tell which instruction
1197 set the CPU is able to translate. The value read from the pseudo variable
1198 should be further examined by using one of the constants defined by the
1199 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1201 It may be used to replace the .IFPxx pseudo instructions or to construct
1202 even more complex expressions.
1208 .if (.cpu .bitand CPU_ISET_65816)
1220 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1222 This builtin pseudo variable is only available in macros. It is replaced by
1223 the actual number of parameters that were given in the macro invocation.
1228 .macro foo arg1, arg2, arg3
1229 .if .paramcount <> 3
1230 .error "Too few parameters for macro foo"
1236 See section <ref id="macros" name="Macros">.
1239 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1241 Reading this pseudo variable will give a constant integer value that
1242 represents the current time in POSIX standard (as seconds since the
1245 It may be used to encode the time of translation somewhere in the created
1251 .dword .time ; Place time here
1255 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1257 Reading this pseudo variable will give the assembler version according to
1258 the following formula:
1260 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1262 It may be used to encode the assembler version or check the assembler for
1263 special features not available with older versions.
1267 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1268 reading the pseudo variable <tt/.VERSION/.
1272 <sect>Pseudo functions<label id="pseudo-functions"><p>
1274 Pseudo functions expect their arguments in parenthesis, and they have a result,
1275 either a string or an expression.
1278 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1280 The function returns the bank byte (that is, bits 16-23) of its argument.
1281 It works identical to the '^' operator.
1283 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1284 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1287 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1289 Builtin function. The function evaluates its argument in braces and yields
1290 "false" if the argument is non blank (there is an argument), and "true" if
1291 there is no argument. The token list that makes up the function argument
1292 may optionally be enclosed in curly braces. This allows the inclusion of
1293 tokens that would otherwise terminate the list (the closing right
1294 parenthesis). The curly braces are not considered part of the list, a list
1295 just consisting of curly braces is considered to be empty.
1297 As an example, the <tt/.IFBLANK/ statement may be replaced by
1305 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1307 Builtin string function. The function allows to concatenate a list of string
1308 constants separated by commas. The result is a string constant that is the
1309 concatenation of all arguments. This function is most useful in macros and
1310 when used together with the <tt/.STRING/ builtin function. The function may
1311 be used in any case where a string constant is expected.
1316 .include .concat ("myheader", ".", "inc")
1319 This is the same as the command
1322 .include "myheader.inc"
1326 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1328 Builtin function. The function evaluates its argument in braces and
1329 yields "true" if the argument is a constant expression (that is, an
1330 expression that yields a constant value at assembly time) and "false"
1331 otherwise. As an example, the .IFCONST statement may be replaced by
1338 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1340 The function returns the high byte (that is, bits 8-15) of its argument.
1341 It works identical to the '>' operator.
1343 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1344 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1347 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1349 The function returns the high word (that is, bits 16-31) of its argument.
1351 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1354 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1356 The function expects a string as its argument, and converts this argument
1357 into an identifier. If the string starts with the current <tt/<ref
1358 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1359 identifier, otherwise it will be converted into a normal identifier.
1364 .macro makelabel arg1, arg2
1365 .ident (.concat (arg1, arg2)):
1368 makelabel "foo", "bar"
1370 .word foobar ; Valid label
1374 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1376 Builtin function. Extracts the left part of a given token list.
1381 .LEFT (<int expr>, <token list>)
1384 The first integer expression gives the number of tokens to extract from
1385 the token list. The second argument is the token list itself. The token
1386 list may optionally be enclosed into curly braces. This allows the
1387 inclusion of tokens that would otherwise terminate the list (the closing
1388 right paren in the given case).
1392 To check in a macro if the given argument has a '#' as first token
1393 (immediate addressing mode), use something like this:
1398 .if (.match (.left (1, {arg}), #))
1400 ; ldax called with immediate operand
1408 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1409 name=".RIGHT"></tt> builtin functions.
1412 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1414 The function returns the low byte (that is, bits 0-7) of its argument.
1415 It works identical to the '<' operator.
1417 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1418 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1421 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1423 The function returns the low word (that is, bits 0-15) of its argument.
1425 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1428 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1430 Builtin function. Matches two token lists against each other. This is
1431 most useful within macros, since macros are not stored as strings, but
1437 .MATCH(<token list #1>, <token list #2>)
1440 Both token list may contain arbitrary tokens with the exception of the
1441 terminator token (comma resp. right parenthesis) and
1448 The token lists may optionally be enclosed into curly braces. This allows
1449 the inclusion of tokens that would otherwise terminate the list (the closing
1450 right paren in the given case). Often a macro parameter is used for any of
1453 Please note that the function does only compare tokens, not token
1454 attributes. So any number is equal to any other number, regardless of the
1455 actual value. The same is true for strings. If you need to compare tokens
1456 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1457 name=".XMATCH"></tt> function.
1461 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1462 while honoring the sign bit. The builtin processor instructions will allow
1463 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1464 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1465 to check for this and print and error for invalid calls.
1470 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1471 .error "Syntax error"
1474 cmp #$80 ; Bit 7 into carry
1475 lsr a ; Shift carry into bit 7
1480 The macro will only accept no arguments, or one argument that must be the
1481 reserved keyword "A".
1483 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1486 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1488 Builtin function. The result is the larger of two values.
1493 .MAX (<value #1>, <value #2>)
1499 ; Reserve space for the larger of two data blocks
1500 savearea: .max (.sizeof (foo), .sizeof (bar))
1503 See: <tt><ref id=".MIN" name=".MIN"></tt>
1506 <sect1><tt>.MID</tt><label id=".MID"><p>
1508 Builtin function. Takes a starting index, a count and a token list as
1509 arguments. Will return part of the token list.
1514 .MID (<int expr>, <int expr>, <token list>)
1517 The first integer expression gives the starting token in the list (the first
1518 token has index 0). The second integer expression gives the number of tokens
1519 to extract from the token list. The third argument is the token list itself.
1520 The token list may optionally be enclosed into curly braces. This allows the
1521 inclusion of tokens that would otherwise terminate the list (the closing
1522 right paren in the given case).
1526 To check in a macro if the given argument has a '<tt/#/' as first token
1527 (immediate addressing mode), use something like this:
1532 .if (.match (.mid (0, 1, {arg}), #))
1534 ; ldax called with immediate operand
1542 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1543 name=".RIGHT"></tt> builtin functions.
1546 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1548 Builtin function. The result is the smaller of two values.
1553 .MIN (<value #1>, <value #2>)
1559 ; Reserve space for some data, but 256 bytes minimum
1560 savearea: .min (.sizeof (foo), 256)
1563 See: <tt><ref id=".MAX" name=".MAX"></tt>
1566 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1568 Builtin function. The function expects an identifier as argument in braces.
1569 The argument is evaluated, and the function yields "true" if the identifier
1570 is a symbol that has already been referenced somewhere in the source file up
1571 to the current position. Otherwise the function yields false. As an example,
1572 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1578 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1581 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1583 Builtin function. Extracts the right part of a given token list.
1588 .RIGHT (<int expr>, <token list>)
1591 The first integer expression gives the number of tokens to extract from the
1592 token list. The second argument is the token list itself. The token list
1593 may optionally be enclosed into curly braces. This allows the inclusion of
1594 tokens that would otherwise terminate the list (the closing right paren in
1597 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1598 name=".MID"></tt> builtin functions.
1601 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1603 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1604 argument can be a struct/union, a struct member, a procedure, or a label. In
1605 case of a procedure or label, its size is defined by the amount of data
1606 placed in the segment where the label is relative to. If a line of code
1607 switches segments (for example in a macro) data placed in other segments
1608 does not count for the size.
1610 Please note that a symbol or scope must exist, before it is used together with
1611 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1612 A scope has preference over a symbol with the same name, so if the last part
1613 of a name represents both, a scope and a symbol, the scope is chosen over the
1616 After the following code:
1619 .struct Point ; Struct size = 4
1624 P: .tag Point ; Declare a point
1625 @P: .tag Point ; Declare another point
1637 .data ; Segment switch!!!
1643 <tag><tt/.sizeof(Point)/</tag>
1644 will have the value 4, because this is the size of struct <tt/Point/.
1646 <tag><tt/.sizeof(Point::xcoord)/</tag>
1647 will have the value 2, because this is the size of the member <tt/xcoord/
1648 in struct <tt/Point/.
1650 <tag><tt/.sizeof(P)/</tag>
1651 will have the value 4, this is the size of the data declared on the same
1652 source line as the label <tt/P/, which is in the same segment that <tt/P/
1655 <tag><tt/.sizeof(@P)/</tag>
1656 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1657 does also work for cheap local symbols.
1659 <tag><tt/.sizeof(Code)/</tag>
1660 will have the value 3, since this is amount of data emitted into the code
1661 segment, the segment that was active when <tt/Code/ was entered. Note that
1662 this value includes the amount of data emitted in child scopes (in this
1663 case <tt/Code::Inner/).
1665 <tag><tt/.sizeof(Code::Inner)/</tag>
1666 will have the value 1 as expected.
1668 <tag><tt/.sizeof(Data)/</tag>
1669 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1670 the segment is switched after entry, this data is emitted into another
1675 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1677 Builtin function. The function accepts a string and an index as
1678 arguments and returns the value of the character at the given position
1679 as an integer value. The index is zero based.
1685 ; Check if the argument string starts with '#'
1686 .if (.strat (Arg, 0) = '#')
1693 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1695 Builtin function. It expects a format string as first argument. The number
1696 and type of the following arguments depend on the format string. The format
1697 string is similar to the one of the C <tt/printf/ function. Missing things
1698 are: Length modifiers, variable width.
1700 The result of the function is a string.
1707 ; Generate an identifier:
1708 .ident (.sprintf ("%s%03d", "label", num)):
1712 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1714 Builtin function. The function accepts an argument in braces and converts
1715 this argument into a string constant. The argument may be an identifier, or
1716 a constant numeric value.
1718 Since you can use a string in the first place, the use of the function may
1719 not be obvious. However, it is useful in macros, or more complex setups.
1724 ; Emulate other assemblers:
1726 .segment .string(name)
1731 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1733 Builtin function. The function accepts a string argument in braces and
1734 evaluates to the length of the string.
1738 The following macro encodes a string as a pascal style string with
1739 a leading length byte.
1743 .byte .strlen(Arg), Arg
1748 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1750 Builtin function. The function accepts a token list in braces. The function
1751 result is the number of tokens given as argument. The token list may
1752 optionally be enclosed into curly braces which are not considered part of
1753 the list and not counted. Enclosement in curly braces allows the inclusion
1754 of tokens that would otherwise terminate the list (the closing right paren
1759 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1760 with the normal 6502 instructions). To translate it into two separate 8 bit
1761 load instructions, the '#' token has to get stripped from the argument:
1765 .if (.match (.mid (0, 1, {arg}), #))
1766 ; ldax called with immediate operand
1767 lda #<(.right (.tcount ({arg})-1, {arg}))
1768 ldx #>(.right (.tcount ({arg})-1, {arg}))
1776 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1778 Builtin function. Matches two token lists against each other. This is
1779 most useful within macros, since macros are not stored as strings, but
1785 .XMATCH(<token list #1>, <token list #2>)
1788 Both token list may contain arbitrary tokens with the exception of the
1789 terminator token (comma resp. right parenthesis) and
1796 The token lists may optionally be enclosed into curly braces. This allows
1797 the inclusion of tokens that would otherwise terminate the list (the closing
1798 right paren in the given case). Often a macro parameter is used for any of
1801 The function compares tokens <em/and/ token values. If you need a function
1802 that just compares the type of tokens, have a look at the <tt><ref
1803 id=".MATCH" name=".MATCH"></tt> function.
1805 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1809 <sect>Control commands<label id="control-commands"><p>
1811 Here's a list of all control commands and a description, what they do:
1814 <sect1><tt>.A16</tt><label id=".A16"><p>
1816 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1818 Note: This command will not emit any code, it will tell the assembler to
1819 create 16 bit operands for immediate accumulator addressing mode.
1821 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1824 <sect1><tt>.A8</tt><label id=".A8"><p>
1826 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1828 Note: This command will not emit any code, it will tell the assembler to
1829 create 8 bit operands for immediate accu addressing mode.
1831 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1834 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1836 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1837 may be used for better readability if the data words are address values. In
1838 65816 mode, the address is forced to be 16 bit wide to fit into the current
1839 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1840 must be followed by a sequence of (not necessarily constant) expressions.
1845 .addr $0D00, $AF13, _Clear
1848 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1852 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1854 Align data to a given boundary. The command expects a constant integer
1855 argument in the range 1 ... 65536, plus an optional second argument
1856 in byte range. If there is a second argument, it is used as fill value,
1857 otherwise the value defined in the linker configuration file is used
1858 (the default for this value is zero).
1860 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1861 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1862 number of bytes, since that would break address calculations within the
1863 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1864 of the alignment, because that allows the number of fill bytes to be
1865 calculated in advance by the assembler. You are therefore required to
1866 specify a matching alignment for the segment in the linker config. The
1867 linker will output a warning if the alignment of the segment is less than
1868 what is necessary to have a correct alignment in the object file.
1876 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1877 commands with different arguments. To allow the assembler to calculate the
1878 number of fill bytes in advance, the alignment of the segment must be a
1879 multiple of each of the alignment factors. This may result in unexpectedly
1880 large alignments for the segment within the module.
1891 For the assembler to be able to align correctly, the segment must be aligned
1892 to the least common multiple of 15 and 18 which is 90. The assembler will
1893 calculate this automatically and will mark the segment with this value.
1895 Unfortunately, the combined alignment may get rather large without the user
1896 knowing about it, wasting space in the final executable. If we add another
1897 alignment to the example above
1908 the assembler will force a segment alignment to the least common multiple of
1909 15, 18 and 251 - which is 22590. To protect the user against errors, the
1910 assembler will issue a warning when the combined alignment exceeds 256. The
1911 command line option <tt><ref id="option--large-alignment"
1912 name="--large-alignment"></tt> will disable this warning.
1914 Please note that with alignments that are a power of two (which were the
1915 only alignments possible in older versions of the assembler), the problem is
1916 less severe, because the least common multiple of powers to the same base is
1917 always the larger one.
1921 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1923 Define a string with a trailing zero.
1928 Msg: .asciiz "Hello world"
1931 This will put the string "Hello world" followed by a binary zero into
1932 the current segment. There may be more strings separated by commas, but
1933 the binary zero is only appended once (after the last one).
1936 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1938 Add an assertion. The command is followed by an expression, an action
1939 specifier, and an optional message that is output in case the assertion
1940 fails. If no message was given, the string "Assertion failed" is used. The
1941 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
1942 <tt/lderror/. In the former two cases, the assertion is evaluated by the
1943 assembler if possible, and in any case, it's also passed to the linker in
1944 the object file (if one is generated). The linker will then evaluate the
1945 expression when segment placement has been done.
1950 .assert * = $8000, error, "Code not at $8000"
1953 The example assertion will check that the current location is at $8000,
1954 when the output file is written, and abort with an error if this is not
1955 the case. More complex expressions are possible. The action specifier
1956 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1957 an error message. In the latter case, generation of the output file is
1958 suppressed in both the assembler and linker.
1961 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1963 Is followed by a plus or a minus character. When switched on (using a
1964 +), undefined symbols are automatically marked as import instead of
1965 giving errors. When switched off (which is the default so this does not
1966 make much sense), this does not happen and an error message is
1967 displayed. The state of the autoimport flag is evaluated when the
1968 complete source was translated, before outputting actual code, so it is
1969 <em/not/ possible to switch this feature on or off for separate sections
1970 of code. The last setting is used for all symbols.
1972 You should probably not use this switch because it delays error
1973 messages about undefined symbols until the link stage. The cc65
1974 compiler (which is supposed to produce correct assembler code in all
1975 circumstances, something which is not true for most assembler
1976 programmers) will insert this command to avoid importing each and every
1977 routine from the runtime library.
1982 .autoimport + ; Switch on auto import
1985 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
1987 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
1988 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
1989 the operator '^' prepended to each expression in its list.
1994 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
1996 TableLookupLo: .lobytes MyTable
1997 TableLookupHi: .hibytes MyTable
1998 TableLookupBank: .bankbytes MyTable
2001 which is equivalent to
2004 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2005 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2006 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2009 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2010 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2011 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2014 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2016 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2017 so this is a shortcut for
2023 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2026 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2028 Define byte sized data. Must be followed by a sequence of (byte ranged)
2029 expressions or strings.
2035 .byt "world", $0D, $00
2039 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2041 Switch on or off case sensitivity on identifiers. The default is off
2042 (that is, identifiers are case sensitive), but may be changed by the
2043 -i switch on the command line.
2044 The command must be followed by a '+' or '-' character to switch the
2045 option on or off respectively.
2050 .case - ; Identifiers are not case sensitive
2054 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2056 Apply a custom mapping for characters. The command is followed by two
2057 numbers in the range 1..255. The first one is the index of the source
2058 character, the second one is the mapping. The mapping applies to all
2059 character and string constants when they generate output, and overrides
2060 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2061 command line switch.
2066 .charmap $41, $61 ; Map 'A' to 'a'
2070 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2072 Switch to the CODE segment. The name of the CODE segment is always
2073 "CODE", so this is a shortcut for
2079 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2082 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2084 Export a symbol and mark it in a special way. The linker is able to build
2085 tables of all such symbols. This may be used to automatically create a list
2086 of functions needed to initialize linked library modules.
2088 Note: The linker has a feature to build a table of marked routines, but it
2089 is your code that must call these routines, so just declaring a symbol with
2090 <tt/.CONDES/ does nothing by itself.
2092 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2093 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2094 is implied by <tt/.CONDES/.
2096 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2097 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2098 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2099 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2100 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2101 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2102 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2104 After the type, an optional priority may be specified. Higher numeric values
2105 mean higher priority. If no priority is given, the default priority of 7 is
2106 used. Be careful when assigning priorities to your own module constructors
2107 so they won't interfere with the ones in the cc65 library.
2112 .condes ModuleInit, constructor
2113 .condes ModInit, 0, 16
2116 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2117 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2118 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2119 name="Module constructors/destructors"> explaining the feature in more
2123 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2125 Export a symbol and mark it as a module constructor. This may be used
2126 together with the linker to build a table of constructor subroutines that
2127 are called by the startup code.
2129 Note: The linker has a feature to build a table of marked routines, but it
2130 is your code that must call these routines, so just declaring a symbol as
2131 constructor does nothing by itself.
2133 A constructor is always exported as an absolute (16 bit) symbol. You don't
2134 need to use an additional <tt/.export/ statement, this is implied by
2135 <tt/.constructor/. It may have an optional priority that is separated by a
2136 comma. Higher numeric values mean a higher priority. If no priority is
2137 given, the default priority of 7 is used. Be careful when assigning
2138 priorities to your own module constructors so they won't interfere with the
2139 ones in the cc65 library.
2144 .constructor ModuleInit
2145 .constructor ModInit, 16
2148 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2149 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2150 <ref id="condes" name="Module constructors/destructors"> explaining the
2151 feature in more detail.
2154 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2156 Switch to the DATA segment. The name of the DATA segment is always
2157 "DATA", so this is a shortcut for
2163 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2166 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2168 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2169 create word sized data in native 65XX format). Must be followed by a
2170 sequence of (word ranged) expressions.
2178 This will emit the bytes
2184 into the current segment in that order.
2187 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2189 Switch on or off debug info generation. The default is off (that is,
2190 the object file will not contain debug infos), but may be changed by the
2191 -g switch on the command line.
2192 The command must be followed by a '+' or '-' character to switch the
2193 option on or off respectively.
2198 .debuginfo + ; Generate debug info
2202 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2204 Start a define style macro definition. The command is followed by an
2205 identifier (the macro name) and optionally by a list of formal arguments
2207 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2208 section <ref id="macros" name="Macros">.
2211 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2213 Delete a classic macro (defined with <tt><ref id=".MACRO"
2214 name=".MACRO"></tt>) . The command is followed by the name of an
2215 existing macro. Its definition will be deleted together with the name.
2216 If necessary, another macro with this name may be defined later.
2218 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2219 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2220 <tt><ref id=".MACRO" name=".MACRO"></tt>
2222 See also section <ref id="macros" name="Macros">.
2225 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2227 Builtin function. The function expects an identifier as argument in braces.
2228 The argument is evaluated, and the function yields "true" if the identifier
2229 is a symbol that is already defined somewhere in the source file up to the
2230 current position. Otherwise the function yields false. As an example, the
2231 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2238 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2240 Export a symbol and mark it as a module destructor. This may be used
2241 together with the linker to build a table of destructor subroutines that
2242 are called by the startup code.
2244 Note: The linker has a feature to build a table of marked routines, but it
2245 is your code that must call these routines, so just declaring a symbol as
2246 constructor does nothing by itself.
2248 A destructor is always exported as an absolute (16 bit) symbol. You don't
2249 need to use an additional <tt/.export/ statement, this is implied by
2250 <tt/.destructor/. It may have an optional priority that is separated by a
2251 comma. Higher numerical values mean a higher priority. If no priority is
2252 given, the default priority of 7 is used. Be careful when assigning
2253 priorities to your own module destructors so they won't interfere with the
2254 ones in the cc65 library.
2259 .destructor ModuleDone
2260 .destructor ModDone, 16
2263 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2264 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2265 section <ref id="condes" name="Module constructors/destructors"> explaining
2266 the feature in more detail.
2269 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2271 Define dword sized data (4 bytes) Must be followed by a sequence of
2277 .dword $12344512, $12FA489
2281 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2283 Conditional assembly: Reverse the current condition.
2286 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2288 Conditional assembly: Reverse current condition and test a new one.
2291 <sect1><tt>.END</tt><label id=".END"><p>
2293 Forced end of assembly. Assembly stops at this point, even if the command
2294 is read from an include file.
2297 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2299 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2302 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2304 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2305 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2308 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2310 Marks the end of a macro definition.
2312 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2313 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2314 <tt><ref id=".MACRO" name=".MACRO"></tt>
2316 See also section <ref id="macros" name="Macros">.
2319 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2321 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2324 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2326 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2329 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2331 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2334 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2336 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2337 command and the separate section named <ref id="structs" name=""Structs
2341 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2343 Start an enumeration. This directive is very similar to the C <tt/enum/
2344 keyword. If a name is given, a new scope is created for the enumeration,
2345 otherwise the enumeration members are placed in the enclosing scope.
2347 In the enumeration body, symbols are declared. The first symbol has a value
2348 of zero, and each following symbol will get the value of the preceding plus
2349 one. This behaviour may be overridden by an explicit assignment. Two symbols
2350 may have the same value.
2362 Above example will create a new scope named <tt/errorcodes/ with three
2363 symbols in it that get the values 0, 1 and 2 respectively. Another way
2364 to write this would have been:
2374 Please note that explicit scoping must be used to access the identifiers:
2377 .word errorcodes::no_error
2380 A more complex example:
2389 EWOULDBLOCK = EAGAIN
2393 In this example, the enumeration does not have a name, which means that the
2394 members will be visible in the enclosing scope and can be used in this scope
2395 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2396 The value for the following members is incremented by one, so <tt/EOK/ would
2397 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2398 override for the value using an already defined symbol.
2401 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2403 Force an assembly error. The assembler will output an error message
2404 preceded by "User error". Assembly is continued but no object file will
2407 This command may be used to check for initial conditions that must be
2408 set before assembling a source file.
2418 .error "Must define foo or bar!"
2422 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2423 <tt><ref id=".OUT" name=".OUT"></tt>,
2424 <tt><ref id=".WARNING" name=".WARNING"></tt>
2427 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2429 Abort a macro expansion immediately. This command is often useful in
2432 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2433 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2434 <tt><ref id=".MACRO" name=".MACRO"></tt>
2436 See also section <ref id="macros" name="Macros">.
2439 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2441 Make symbols accessible from other modules. Must be followed by a comma
2442 separated list of symbols to export, with each one optionally followed by an
2443 address specification and (also optional) an assignment. Using an additional
2444 assignment in the export statement allows to define and export a symbol in
2445 one statement. The default is to export the symbol with the address size it
2446 actually has. The assembler will issue a warning, if the symbol is exported
2447 with an address size smaller than the actual address size.
2454 .export foobar: far = foo * bar
2455 .export baz := foobar, zap: far = baz - bar
2458 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2461 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2464 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2466 Make symbols accessible from other modules. Must be followed by a comma
2467 separated list of symbols to export. The exported symbols are explicitly
2468 marked as zero page symbols. An assignment may be included in the
2469 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2476 .exportzp baz := $02
2479 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2482 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2484 Define far (24 bit) address data. The command must be followed by a
2485 sequence of (not necessarily constant) expressions.
2490 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2493 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2496 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2498 Force an assembly error and terminate assembly. The assembler will output an
2499 error message preceded by "User error" and will terminate assembly
2502 This command may be used to check for initial conditions that must be
2503 set before assembling a source file.
2513 .fatal "Must define foo or bar!"
2517 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2518 <tt><ref id=".OUT" name=".OUT"></tt>,
2519 <tt><ref id=".WARNING" name=".WARNING"></tt>
2522 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2524 This directive may be used to enable one or more compatibility features
2525 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2526 possible, it may be useful when porting sources written for other
2527 assemblers. There is no way to switch a feature off, once you have
2528 enabled it, so using
2534 will enable the feature until end of assembly is reached.
2536 The following features are available:
2540 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2542 Accept the at character (`@') as a valid character in identifiers. The
2543 at character is not allowed to start an identifier, even with this
2546 <tag><tt>c_comments</tt></tag>
2548 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2549 comment terminators. Note that C comments may not be nested. There's also a
2550 pitfall when using C like comments: All statements must be terminated by
2551 "end-of-line". Using C like comments, it is possible to hide the newline,
2552 which results in error messages. See the following non working example:
2555 lda #$00 /* This comment hides the newline
2559 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2561 Accept the dollar sign (`$') as a valid character in identifiers. The
2562 dollar character is not allowed to start an identifier, even with this
2565 <tag><tt>dollar_is_pc</tt></tag>
2567 The dollar sign may be used as an alias for the star (`*'), which
2568 gives the value of the current PC in expressions.
2569 Note: Assignment to the pseudo variable is not allowed.
2571 <tag><tt>labels_without_colons</tt></tag>
2573 Allow labels without a trailing colon. These labels are only accepted,
2574 if they start at the beginning of a line (no leading white space).
2576 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2578 Accept the dot (`.') as the first character of an identifier. This may be
2579 used for example to create macro names that start with a dot emulating
2580 control directives of other assemblers. Note however, that none of the
2581 reserved keywords built into the assembler, that starts with a dot, may be
2582 overridden. When using this feature, you may also get into trouble if
2583 later versions of the assembler define new keywords starting with a dot.
2585 <tag><tt>loose_char_term</tt></tag>
2587 Accept single quotes as well as double quotes as terminators for char
2590 <tag><tt>loose_string_term</tt></tag>
2592 Accept single quotes as well as double quotes as terminators for string
2595 <tag><tt>missing_char_term</tt></tag>
2597 Accept single quoted character constants where the terminating quote is
2602 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2603 loose_string_term/, since in this case the input would be ambiguous.
2605 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2607 This feature makes relocatable/absolute mode local to the current segment.
2608 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2609 effect will only enable absolute mode for the current segment. Dito for
2610 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2612 <tag><tt>pc_assignment</tt></tag>
2614 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2615 is enabled). Such an assignment is handled identical to the <tt><ref
2616 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2617 removing the lines with the assignments may also be an option when porting
2618 code written for older assemblers).
2620 <tag><tt>ubiquitous_idents</tt></tag>
2622 Allow the use of instructions names as names for macros and symbols. This
2623 makes it possible to "overload" instructions by defining a macro with the
2624 same name. This does also make it possible to introduce hard to find errors
2625 in your code, so be careful!
2629 It is also possible to specify features on the command line using the
2630 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2631 This is useful when translating sources written for older assemblers, when
2632 you don't want to change the source code.
2634 As an example, to translate sources written for Andre Fachats xa65
2635 assembler, the features
2638 labels_without_colons, pc_assignment, loose_char_term
2641 may be helpful. They do not make ca65 completely compatible, so you may not
2642 be able to translate the sources without changes, even when enabling these
2643 features. However, I have found several sources that translate without
2644 problems when enabling these features on the command line.
2647 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2649 Insert an option string into the object file. There are two forms of
2650 this command, one specifies the option by a keyword, the second
2651 specifies it as a number. Since usage of the second one needs knowledge
2652 of the internal encoding, its use is not recommended and I will only
2653 describe the first form here.
2655 The command is followed by one of the keywords
2663 a comma and a string. The option is written into the object file
2664 together with the string value. This is currently unidirectional and
2665 there is no way to actually use these options once they are in the
2671 .fileopt comment, "Code stolen from my brother"
2672 .fileopt compiler, "BASIC 2.0"
2673 .fopt author, "J. R. User"
2677 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2679 Import an absolute symbol from another module. The command is followed by a
2680 comma separated list of symbols to import. The command is similar to <tt>
2681 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2682 written to the generated object file, even if the symbol is never referenced
2683 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2684 references for unused symbols).
2689 .forceimport needthisone, needthistoo
2692 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2695 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2697 Declare symbols as global. Must be followed by a comma separated list of
2698 symbols to declare. Symbols from the list, that are defined somewhere in the
2699 source, are exported, all others are imported. Additional <tt><ref
2700 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2701 name=".EXPORT"></tt> commands for the same symbol are allowed.
2710 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2712 Declare symbols as global. Must be followed by a comma separated list of
2713 symbols to declare. Symbols from the list, that are defined somewhere in the
2714 source, are exported, all others are imported. Additional <tt><ref
2715 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2716 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2717 in the list are explicitly marked as zero page symbols.
2725 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2727 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2728 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2729 the operator '>' prepended to each expression in its list.
2734 .lobytes $1234, $2345, $3456, $4567
2735 .hibytes $fedc, $edcb, $dcba, $cba9
2738 which is equivalent to
2741 .byte $34, $45, $56, $67
2742 .byte $fe, $ed, $dc, $cb
2748 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2750 TableLookupLo: .lobytes MyTable
2751 TableLookupHi: .hibytes MyTable
2754 which is equivalent to
2757 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2758 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2761 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2762 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2763 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2766 <sect1><tt>.I16</tt><label id=".I16"><p>
2768 Valid only in 65816 mode. Switch the index registers to 16 bit.
2770 Note: This command will not emit any code, it will tell the assembler to
2771 create 16 bit operands for immediate operands.
2773 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2774 name=".SMART"></tt> commands.
2777 <sect1><tt>.I8</tt><label id=".I8"><p>
2779 Valid only in 65816 mode. Switch the index registers to 8 bit.
2781 Note: This command will not emit any code, it will tell the assembler to
2782 create 8 bit operands for immediate operands.
2784 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2785 name=".SMART"></tt> commands.
2788 <sect1><tt>.IF</tt><label id=".IF"><p>
2790 Conditional assembly: Evaluate an expression and switch assembler output
2791 on or off depending on the expression. The expression must be a constant
2792 expression, that is, all operands must be defined.
2794 A expression value of zero evaluates to FALSE, any other value evaluates
2798 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2800 Conditional assembly: Check if there are any remaining tokens in this line,
2801 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2802 condition is not true, further lines are not assembled until an <tt><ref
2803 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2804 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2806 This command is often used to check if a macro parameter was given. Since an
2807 empty macro parameter will evaluate to nothing, the condition will evaluate
2808 to FALSE if an empty parameter was given.
2822 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2825 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2827 Conditional assembly: Evaluate an expression and switch assembler output
2828 on or off depending on the constness of the expression.
2830 A const expression evaluates to to TRUE, a non const expression (one
2831 containing an imported or currently undefined symbol) evaluates to
2834 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2837 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2839 Conditional assembly: Check if a symbol is defined. Must be followed by
2840 a symbol name. The condition is true if the the given symbol is already
2841 defined, and false otherwise.
2843 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2846 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2848 Conditional assembly: Check if there are any remaining tokens in this line,
2849 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2850 condition is not true, further lines are not assembled until an <tt><ref
2851 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2852 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2854 This command is often used to check if a macro parameter was given.
2855 Since an empty macro parameter will evaluate to nothing, the condition
2856 will evaluate to FALSE if an empty parameter was given.
2869 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2872 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2874 Conditional assembly: Check if a symbol is defined. Must be followed by
2875 a symbol name. The condition is true if the the given symbol is not
2876 defined, and false otherwise.
2878 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2881 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2883 Conditional assembly: Check if a symbol is referenced. Must be followed
2884 by a symbol name. The condition is true if if the the given symbol was
2885 not referenced before, and false otherwise.
2887 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2890 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2892 Conditional assembly: Check if the assembler is currently in 6502 mode
2893 (see <tt><ref id=".P02" name=".P02"></tt> command).
2896 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2898 Conditional assembly: Check if the assembler is currently in 65816 mode
2899 (see <tt><ref id=".P816" name=".P816"></tt> command).
2902 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2904 Conditional assembly: Check if the assembler is currently in 65C02 mode
2905 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2908 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2910 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2911 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2914 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2916 Conditional assembly: Check if a symbol is referenced. Must be followed
2917 by a symbol name. The condition is true if if the the given symbol was
2918 referenced before, and false otherwise.
2920 This command may be used to build subroutine libraries in include files
2921 (you may use separate object modules for this purpose too).
2926 .ifref ToHex ; If someone used this subroutine
2927 ToHex: tay ; Define subroutine
2933 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2936 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2938 Import a symbol from another module. The command is followed by a comma
2939 separated list of symbols to import, with each one optionally followed by
2940 an address specification.
2946 .import bar: zeropage
2949 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2952 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2954 Import a symbol from another module. The command is followed by a comma
2955 separated list of symbols to import. The symbols are explicitly imported
2956 as zero page symbols (that is, symbols with values in byte range).
2964 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2967 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2969 Include a file as binary data. The command expects a string argument
2970 that is the name of a file to include literally in the current segment.
2971 In addition to that, a start offset and a size value may be specified,
2972 separated by commas. If no size is specified, all of the file from the
2973 start offset to end-of-file is used. If no start position is specified
2974 either, zero is assumed (which means that the whole file is inserted).
2979 ; Include whole file
2980 .incbin "sprites.dat"
2982 ; Include file starting at offset 256
2983 .incbin "music.dat", $100
2985 ; Read 100 bytes starting at offset 200
2986 .incbin "graphics.dat", 200, 100
2990 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2992 Include another file. Include files may be nested up to a depth of 16.
3001 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3003 Export a symbol and mark it as an interruptor. This may be used together
3004 with the linker to build a table of interruptor subroutines that are called
3007 Note: The linker has a feature to build a table of marked routines, but it
3008 is your code that must call these routines, so just declaring a symbol as
3009 interruptor does nothing by itself.
3011 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3012 need to use an additional <tt/.export/ statement, this is implied by
3013 <tt/.interruptor/. It may have an optional priority that is separated by a
3014 comma. Higher numeric values mean a higher priority. If no priority is
3015 given, the default priority of 7 is used. Be careful when assigning
3016 priorities to your own module constructors so they won't interfere with the
3017 ones in the cc65 library.
3022 .interruptor IrqHandler
3023 .interruptor Handler, 16
3026 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3027 section <ref id="condes" name="Module constructors/destructors"> explaining
3028 the feature in more detail.
3031 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3033 Switch on or off line continuations using the backslash character
3034 before a newline. The option is off by default.
3035 Note: Line continuations do not work in a comment. A backslash at the
3036 end of a comment is treated as part of the comment and does not trigger
3038 The command must be followed by a '+' or '-' character to switch the
3039 option on or off respectively.
3044 .linecont + ; Allow line continuations
3047 #$20 ; This is legal now
3051 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3053 Enable output to the listing. The command must be followed by a boolean
3054 switch ("on", "off", "+" or "-") and will enable or disable listing
3056 The option has no effect if the listing is not enabled by the command line
3057 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3058 to the listing file, if the counter is greater than zero, and suppressed if
3059 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3065 .list on ; Enable listing output
3069 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3071 Set, how many bytes are shown in the listing for one source line. The
3072 default is 12, so the listing will show only the first 12 bytes for any
3073 source line that generates more than 12 bytes of code or data.
3074 The directive needs an argument, which is either "unlimited", or an
3075 integer constant in the range 4..255.
3080 .listbytes unlimited ; List all bytes
3081 .listbytes 12 ; List the first 12 bytes
3082 .incbin "data.bin" ; Include large binary file
3086 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3088 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3089 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3090 the operator '<' prepended to each expression in its list.
3095 .lobytes $1234, $2345, $3456, $4567
3096 .hibytes $fedc, $edcb, $dcba, $cba9
3099 which is equivalent to
3102 .byte $34, $45, $56, $67
3103 .byte $fe, $ed, $dc, $cb
3109 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3111 TableLookupLo: .lobytes MyTable
3112 TableLookupHi: .hibytes MyTable
3115 which is equivalent to
3118 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3119 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3122 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3123 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3124 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3127 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3129 This command may only be used inside a macro definition. It declares a
3130 list of identifiers as local to the macro expansion.
3132 A problem when using macros are labels: Since they don't change their name,
3133 you get a "duplicate symbol" error if the macro is expanded the second time.
3134 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3135 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3138 Some other assemblers start a new lexical block inside a macro expansion.
3139 This has some drawbacks however, since that will not allow <em/any/ symbol
3140 to be visible outside a macro, a feature that is sometimes useful. The
3141 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3142 to address the problem.
3144 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3148 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3150 Defines the character that start "cheap" local labels. You may use one
3151 of '@' and '?' as start character. The default is '@'.
3153 Cheap local labels are labels that are visible only between two non
3154 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3155 using explicit lexical nesting.
3162 Clear: lda #$00 ; Global label
3163 ?Loop: sta Mem,y ; Local label
3167 Sub: ... ; New global label
3168 bne ?Loop ; ERROR: Unknown identifier!
3172 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3174 Insert a predefined macro package. The command is followed by an
3175 identifier specifying the macro package to insert. Available macro
3179 atari Defines the scrcode macro.
3180 cbm Defines the scrcode macro.
3181 cpu Defines constants for the .CPU variable.
3182 generic Defines generic macros like add and sub.
3183 longbranch Defines conditional long jump macros.
3186 Including a macro package twice, or including a macro package that
3187 redefines already existing macros will lead to an error.
3192 .macpack longbranch ; Include macro package
3194 cmp #$20 ; Set condition codes
3195 jne Label ; Jump long on condition
3198 Macro packages are explained in more detail in section <ref
3199 id="macropackages" name="Macro packages">.
3202 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3204 Start a classic macro definition. The command is followed by an identifier
3205 (the macro name) and optionally by a comma separated list of identifiers
3206 that are macro parameters. A macro definition is terminated by <tt><ref
3207 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3212 .macro ldax arg ; Define macro ldax
3217 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3218 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3219 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3221 See also section <ref id="macros" name="Macros">.
3224 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3226 Start a section of absolute code. The command is followed by a constant
3227 expression that gives the new PC counter location for which the code is
3228 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3231 By default, absolute/relocatable mode is global (valid even when switching
3232 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3233 it can be made segment local.
3235 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3236 code at a specific address is the job of the linker, not the assembler, so
3237 there is usually no reason to assemble code to a specific address.
3242 .org $7FF ; Emit code starting at $7FF
3246 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3248 Output a string to the console without producing an error. This command
3249 is similar to <tt/.ERROR/, however, it does not force an assembler error
3250 that prevents the creation of an object file.
3255 .out "This code was written by the codebuster(tm)"
3258 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3259 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3260 <tt><ref id=".WARNING" name=".WARNING"></tt>
3263 <sect1><tt>.P02</tt><label id=".P02"><p>
3265 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3266 instructions. This is the default if not overridden by the
3267 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3269 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3270 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3273 <sect1><tt>.P816</tt><label id=".P816"><p>
3275 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3276 6502 instruction sets.
3278 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3279 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3282 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3284 Set the page length for the listing. Must be followed by an integer
3285 constant. The value may be "unlimited", or in the range 32 to 127. The
3286 statement has no effect if no listing is generated. The default value is -1
3287 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3288 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3289 after assembly is complete, you cannot use multiple line lengths with one
3290 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3295 .pagelength 66 ; Use 66 lines per listing page
3297 .pagelength unlimited ; Unlimited page length
3301 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3303 Enable the 65C02 instructions set. This instruction set includes all
3304 6502 and 65SC02 instructions.
3306 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3307 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3310 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3312 Pop the last CPU setting from the stack, and activate it.
3314 This command will switch back to the CPU that was last pushed onto the CPU
3315 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3316 remove this entry from the stack.
3318 The assembler will print an error message if the CPU stack is empty when
3319 this command is issued.
3321 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3322 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3325 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3327 Pop the last pushed segment from the stack, and set it.
3329 This command will switch back to the segment that was last pushed onto the
3330 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3331 command, and remove this entry from the stack.
3333 The assembler will print an error message if the segment stack is empty
3334 when this command is issued.
3336 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3339 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3341 Start a nested lexical level with the given name and adds a symbol with this
3342 name to the enclosing scope. All new symbols from now on are in the local
3343 lexical level and are accessible from outside only via <ref id="scopesyntax"
3344 name="explicit scope specification">. Symbols defined outside this local
3345 level may be accessed as long as their names are not used for new symbols
3346 inside the level. Symbols names in other lexical levels do not clash, so you
3347 may use the same names for identifiers. The lexical level ends when the
3348 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3349 may be nested up to a depth of 16 (this is an artificial limit to protect
3350 against errors in the source).
3352 Note: Macro names are always in the global level and in a separate name
3353 space. There is no special reason for this, it's just that I've never
3354 had any need for local macro definitions.
3359 .proc Clear ; Define Clear subroutine, start new level
3361 L1: sta Mem,y ; L1 is local and does not cause a
3362 ; duplicate symbol error if used in other
3365 bne L1 ; Reference local symbol
3367 .endproc ; Leave lexical level
3370 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3374 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3376 Enable the 65SC02 instructions set. This instruction set includes all
3379 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3380 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3383 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3385 Push the currently active CPU onto a stack. The stack has a size of 8
3388 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3389 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3390 later, without knowledge of the current CPU setting.
3392 The assembler will print an error message if the CPU stack is already full,
3393 when this command is issued.
3395 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3396 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3399 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3401 Push the currently active segment onto a stack. The entries on the stack
3402 include the name of the segment and the segment type. The stack has a size
3405 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3406 to switch to another segment and to restore the old segment later, without
3407 even knowing the name and type of the current segment.
3409 The assembler will print an error message if the segment stack is already
3410 full, when this command is issued.
3412 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3415 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3417 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3418 name=".ORG"></tt> command.
3421 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3423 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3424 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3425 a constant expression that tells how many times the commands in the body
3426 should get repeated. Optionally, a comma and an identifier may be specified.
3427 If this identifier is found in the body of the repeat statement, it is
3428 replaced by the current repeat count (starting with zero for the first time
3429 the body is repeated).
3431 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3432 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3433 level will be used, not the one from the outer level.
3437 The following macro will emit a string that is "encrypted" in that all
3438 characters of the string are XORed by the value $55.
3442 .repeat .strlen(Arg), I
3443 .byte .strat(Arg, I) ^ $55
3448 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3451 <sect1><tt>.RES</tt><label id=".RES"><p>
3453 Reserve storage. The command is followed by one or two constant
3454 expressions. The first one is mandatory and defines, how many bytes of
3455 storage should be defined. The second, optional expression must by a
3456 constant byte value that will be used as value of the data. If there
3457 is no fill value given, the linker will use the value defined in the
3458 linker configuration file (default: zero).
3463 ; Reserve 12 bytes of memory with value $AA
3468 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3470 Switch to the RODATA segment. The name of the RODATA segment is always
3471 "RODATA", so this is a shortcut for
3477 The RODATA segment is a segment that is used by the compiler for
3478 readonly data like string constants.
3480 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3483 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3485 Start a nested lexical level with the given name. All new symbols from now
3486 on are in the local lexical level and are accessible from outside only via
3487 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3488 outside this local level may be accessed as long as their names are not used
3489 for new symbols inside the level. Symbols names in other lexical levels do
3490 not clash, so you may use the same names for identifiers. The lexical level
3491 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3492 read. Lexical levels may be nested up to a depth of 16 (this is an
3493 artificial limit to protect against errors in the source).
3495 Note: Macro names are always in the global level and in a separate name
3496 space. There is no special reason for this, it's just that I've never
3497 had any need for local macro definitions.
3502 .scope Error ; Start new scope named Error
3504 File = 1 ; File error
3505 Parse = 2 ; Parse error
3506 .endscope ; Close lexical level
3509 lda #Error::File ; Use symbol from scope Error
3512 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3516 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3518 Switch to another segment. Code and data is always emitted into a
3519 segment, that is, a named section of data. The default segment is
3520 "CODE". There may be up to 254 different segments per object file
3521 (and up to 65534 per executable). There are shortcut commands for
3522 the most common segments ("CODE", "DATA" and "BSS").
3524 The command is followed by a string containing the segment name (there are
3525 some constraints for the name - as a rule of thumb use only those segment
3526 names that would also be valid identifiers). There may also be an optional
3527 address size separated by a colon. See the section covering <tt/<ref
3528 id="address-sizes" name="address sizes">/ for more information.
3530 The default address size for a segment depends on the memory model specified
3531 on the command line. The default is "absolute", which means that you don't
3532 have to use an address size modifier in most cases.
3534 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3535 That is, the segment will reside somewhere in core memory outside the zero
3536 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3537 page and direct (short) addressing is possible for data in this segment.
3539 Beware: Only labels in a segment with the zeropage attribute are marked
3540 as reachable by short addressing. The `*' (PC counter) operator will
3541 work as in other segments and will create absolute variable values.
3543 Please note that a segment cannot have two different address sizes. A
3544 segment specified as zeropage cannot be declared as being absolute later.
3549 .segment "ROM2" ; Switch to ROM2 segment
3550 .segment "ZP2": zeropage ; New direct segment
3551 .segment "ZP2" ; Ok, will use last attribute
3552 .segment "ZP2": absolute ; Error, redecl mismatch
3555 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3556 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3557 id=".RODATA" name=".RODATA"></tt>
3560 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3562 Switch the CPU instruction set. The command is followed by a string that
3563 specifies the CPU. Possible values are those that can also be supplied to
3564 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3565 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3566 note that support for the sunplus CPU is not available in the freeware
3567 version, because the instruction set of the sunplus CPU is "proprietary
3570 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3571 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3572 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3573 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3574 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3575 <tt><ref id=".P02" name=".P02"></tt>,
3576 <tt><ref id=".P816" name=".P816"></tt>,
3577 <tt><ref id=".PC02" name=".PC02"></tt>,
3578 <tt><ref id=".PSC02" name=".PSC02"></tt>
3581 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3583 Switch on or off smart mode. The command must be followed by a '+' or '-'
3584 character to switch the option on or off respectively. The default is off
3585 (that is, the assembler doesn't try to be smart), but this default may be
3586 changed by the -s switch on the command line.
3588 In smart mode the assembler will do the following:
3591 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3592 and update the operand sizes accordingly. If the operand of such an
3593 instruction cannot be evaluated by the assembler (for example, because
3594 the operand is an imported symbol), a warning is issued. Beware: Since
3595 the assembler cannot trace the execution flow this may lead to false
3596 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3597 instructions to tell the assembler about the current settings.
3598 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3599 used within a procedure declared as <tt/far/, or if the procedure has
3600 no explicit address specification, but it is <tt/far/ because of the
3608 .smart - ; Stop being smart
3611 See: <tt><ref id=".A16" name=".A16"></tt>,
3612 <tt><ref id=".A8" name=".A8"></tt>,
3613 <tt><ref id=".I16" name=".I16"></tt>,
3614 <tt><ref id=".I8" name=".I8"></tt>
3617 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3619 Starts a struct definition. Structs are covered in a separate section named
3620 <ref id="structs" name=""Structs and unions"">.
3622 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3625 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3627 Enable the SunPlus instructions set. This command will not work in the
3628 freeware version of the assembler, because the instruction set is
3629 "proprietary and confidential".
3631 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3632 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3633 <tt><ref id=".P816" name=".P816"></tt>
3636 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3638 Allocate space for a struct or union.
3649 .tag Point ; Allocate 4 bytes
3653 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3655 Delete a define style macro definition. The command is followed by an
3656 identifier which specifies the name of the macro to delete. Macro
3657 replacement is switched of when reading the token following the command
3658 (otherwise the macro name would be replaced by its replacement list).
3660 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3661 section <ref id="macros" name="Macros">.
3664 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3666 Force an assembly warning. The assembler will output a warning message
3667 preceded by "User warning". This warning will always be output, even if
3668 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3669 command line option.
3671 This command may be used to output possible problems when assembling
3680 .warning "Forward jump in jne, cannot optimize!"
3690 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>
3691 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3692 <tt><ref id=".OUT" name=".OUT"></tt>
3695 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3697 Define word sized data. Must be followed by a sequence of (word ranged,
3698 but not necessarily constant) expressions.
3703 .word $0D00, $AF13, _Clear
3707 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3709 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3710 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3714 .segment "ZEROPAGE", zeropage
3717 Because of the "zeropage" attribute, labels declared in this segment are
3718 addressed using direct addressing mode if possible. You <em/must/ instruct
3719 the linker to place this segment somewhere in the address range 0..$FF
3720 otherwise you will get errors.
3722 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3726 <sect>Macros<label id="macros"><p>
3729 <sect1>Introduction<p>
3731 Macros may be thought of as "parametrized super instructions". Macros are
3732 sequences of tokens that have a name. If that name is used in the source
3733 file, the macro is "expanded", that is, it is replaced by the tokens that
3734 were specified when the macro was defined.
3737 <sect1>Macros without parameters<p>
3739 In its simplest form, a macro does not have parameters. Here's an
3743 .macro asr ; Arithmetic shift right
3744 cmp #$80 ; Put bit 7 into carry
3745 ror ; Rotate right with carry
3749 The macro above consists of two real instructions, that are inserted into
3750 the code, whenever the macro is expanded. Macro expansion is simply done
3751 by using the name, like this:
3760 <sect1>Parametrized macros<p>
3762 When using macro parameters, macros can be even more useful:
3776 When calling the macro, you may give a parameter, and each occurrence of
3777 the name "addr" in the macro definition will be replaced by the given
3796 A macro may have more than one parameter, in this case, the parameters
3797 are separated by commas. You are free to give less parameters than the
3798 macro actually takes in the definition. You may also leave intermediate
3799 parameters empty. Empty parameters are replaced by empty space (that is,
3800 they are removed when the macro is expanded). If you have a look at our
3801 macro definition above, you will see, that replacing the "addr" parameter
3802 by nothing will lead to wrong code in most lines. To help you, writing
3803 macros with a variable parameter list, there are some control commands:
3805 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3806 returns true, if there are any tokens on the remainder of the line. Since
3807 empty parameters are replaced by nothing, this may be used to test if a given
3808 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3811 Look at this example:
3814 .macro ldaxy a, x, y
3827 This macro may be called as follows:
3830 ldaxy 1, 2, 3 ; Load all three registers
3832 ldaxy 1, , 3 ; Load only a and y
3834 ldaxy , , 3 ; Load y only
3837 There's another helper command for determining, which macro parameters are
3838 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3839 replaced by the parameter count given, <em/including/ intermediate empty macro
3843 ldaxy 1 ; .PARAMCOUNT = 1
3844 ldaxy 1,,3 ; .PARAMCOUNT = 3
3845 ldaxy 1,2 ; .PARAMCOUNT = 2
3846 ldaxy 1, ; .PARAMCOUNT = 2
3847 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3850 Macro parameters may optionally be enclosed into curly braces. This allows the
3851 inclusion of tokens that would otherwise terminate the parameter (the comma in
3852 case of a macro parameter).
3855 .macro foo arg1, arg2
3859 foo ($00,x) ; Two parameters passed
3860 foo {($00,x)} ; One parameter passed
3863 In the first case, the macro is called with two parameters: '<tt/($00/'
3864 and 'x)'. The comma is not passed to the macro, since it is part of the
3865 calling sequence, not the parameters.
3867 In the second case, '($00,x)' is passed to the macro, this time
3868 including the comma.
3871 <sect1>Detecting parameter types<p>
3873 Sometimes it is nice to write a macro that acts differently depending on the
3874 type of the argument supplied. An example would be a macro that loads a 16 bit
3875 value from either an immediate operand, or from memory. The <tt/<ref
3876 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3877 functions will allow you to do exactly this:
3881 .if (.match (.left (1, {arg}), #))
3883 lda #<(.right (.tcount ({arg})-1, {arg}))
3884 ldx #>(.right (.tcount ({arg})-1, {arg}))
3886 ; assume absolute or zero page
3893 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3894 check if its argument begins with a hash mark. If so, two immediate loads are
3895 emitted, Otherwise a load from an absolute zero page memory location is
3896 assumed. Please note how the curly braces are used to enclose parameters to
3897 pseudo functions handling token lists. This is necessary, because the token
3898 lists may include commas or parens, which would be treated by the assembler
3901 The macro can be used as
3906 ldax #$1234 ; X=$12, A=$34
3908 ldax foo ; X=$56, A=$78
3912 <sect1>Recursive macros<p>
3914 Macros may be used recursively:
3917 .macro push r1, r2, r3
3926 There's also a special macro to help writing recursive macros: <tt><ref
3927 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3931 .macro push r1, r2, r3, r4, r5, r6, r7
3933 ; First parameter is empty
3939 push r2, r3, r4, r5, r6, r7
3943 When expanding this macro, the expansion will push all given parameters
3944 until an empty one is encountered. The macro may be called like this:
3947 push $20, $21, $32 ; Push 3 ZP locations
3948 push $21 ; Push one ZP location
3952 <sect1>Local symbols inside macros<p>
3954 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3955 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3956 Have a look at the inc16 macro above. Here is it again:
3970 If you have a closer look at the code, you will notice, that it could be
3971 written more efficiently, like this:
3982 But imagine what happens, if you use this macro twice? Since the label
3983 "Skip" has the same name both times, you get a "duplicate symbol" error.
3984 Without a way to circumvent this problem, macros are not as useful, as
3985 they could be. One solution is, to start a new lexical block inside the
3999 Now the label is local to the block and not visible outside. However,
4000 sometimes you want a label inside the macro to be visible outside. To make
4001 that possible, there's a new command that's only usable inside a macro
4002 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
4003 or more symbols as local to the macro expansion. The names of local variables
4004 are replaced by a unique name in each separate macro expansion. So we could
4005 also solve the problem above by using <tt/.LOCAL/:
4009 .local Skip ; Make Skip a local symbol
4016 Skip: ; Not visible outside
4021 <sect1>C style macros<p>
4023 Starting with version 2.5 of the assembler, there is a second macro type
4024 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4025 similar to the classic macro type described above, but behaviour is sometimes
4030 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4031 span more than a line. You may use line continuation (see <tt><ref
4032 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4033 more than one line for increased readability, but the macro itself
4034 may not contain an end-of-line token.
4036 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4037 the name space with classic macros, but they are detected and replaced
4038 at the scanner level. While classic macros may be used in every place,
4039 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4040 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4041 they are more versatile in some situations.
4043 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4044 parameters. While classic macros may have empty parameters, this is
4045 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4046 For this macro type, the number of actual parameters must match
4047 exactly the number of formal parameters.
4049 To make this possible, formal parameters are enclosed in braces when
4050 defining the macro. If there are no parameters, the empty braces may
4053 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4054 contain end-of-line tokens, there are things that cannot be done. They
4055 may not contain several processor instructions for example. So, while
4056 some things may be done with both macro types, each type has special
4057 usages. The types complement each other.
4061 Let's look at a few examples to make the advantages and disadvantages
4064 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4065 following <tt/.DEFINE/:
4070 foo EQU $1234 ; This is accepted now
4073 You may use the directive to define string constants used elsewhere:
4076 ; Define the version number
4077 .define VERSION "12.3a"
4083 Macros with parameters may also be useful:
4086 .define DEBUG(message) .out message
4088 DEBUG "Assembling include file #3"
4091 Note that, while formal parameters have to be placed in braces, this is
4092 not true for the actual parameters. Beware: Since the assembler cannot
4093 detect the end of one parameter, only the first token is used. If you
4094 don't like that, use classic macros instead:
4102 (This is an example where a problem can be solved with both macro types).
4105 <sect1>Characters in macros<p>
4107 When using the <ref id="option-t" name="-t"> option, characters are translated
4108 into the target character set of the specific machine. However, this happens
4109 as late as possible. This means that strings are translated if they are part
4110 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4111 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4112 used as part of an expression.
4114 This behaviour is very intuitive outside of macros but may be confusing when
4115 doing more complex macros. If you compare characters against numeric values,
4116 be sure to take the translation into account.
4119 <sect1>Deleting macros<p>
4121 Macros can be deleted. This will not work if the macro that should be deleted
4122 is currently expanded as in the following non working example:
4126 .delmacro notworking
4129 notworking ; Will not work
4132 The commands to delete classic and define style macros differ. Classic macros
4133 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4134 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4135 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4143 .byte value ; Emit one byte with value 1
4144 mac ; Emit another byte with value 2
4149 .byte value ; Error: Unknown identifier
4150 mac ; Error: Missing ":"
4153 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4154 the name of such a macro is replaced by its replacement list on a very low
4155 level. To get the actual name, macro replacement has to be switched off when
4156 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4157 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4158 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4159 different commands increases flexibility.
4162 <sect>Macro packages<label id="macropackages"><p>
4164 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4165 macro packages may be included with just one command. Available macro packages
4169 <sect1><tt>.MACPACK generic</tt><p>
4171 This macro package defines macros that are useful in almost any program.
4172 Currently defined macros are:
4207 <sect1><tt>.MACPACK longbranch</tt><p>
4209 This macro package defines long conditional jumps. They are named like the
4210 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4211 definition for the "<tt/jeq/" macro, the other macros are built using the same
4216 .if .def(Target) .and ((*+2)-(Target) <= 127)
4225 All macros expand to a short branch, if the label is already defined (back
4226 jump) and is reachable with a short jump. Otherwise the macro expands to a
4227 conditional branch with the branch condition inverted, followed by an absolute
4228 jump to the actual branch target.
4230 The package defines the following macros:
4233 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4238 <sect1><tt>.MACPACK atari</tt><p>
4240 The atari macro package will define a macro named <tt/scrcode/. It takes a
4241 string as argument and places this string into memory translated into screen
4245 <sect1><tt>.MACPACK cbm</tt><p>
4247 The cbm macro package will define a macro named <tt/scrcode/. It takes a
4248 string as argument and places this string into memory translated into screen
4252 <sect1><tt>.MACPACK cpu</tt><p>
4254 This macro package does not define any macros but constants used to examine
4255 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4256 each supported CPU a constant similar to
4268 is defined. These constants may be used to determine the exact type of the
4269 currently enabled CPU. In addition to that, for each CPU instruction set,
4270 another constant is defined:
4282 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4283 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4284 currently enabled CPU supports a specific instruction set. For example the
4285 65C02 supports all instructions of the 65SC02 CPU, so it has the
4286 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4290 .if (.cpu .bitand CPU_ISET_65SC02)
4298 it is possible to determine if the
4304 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4305 CPUs (the latter two are upwards compatible to the 65SC02).
4309 <sect>Predefined constants<label id="predefined-constants"><p>
4311 For better orthogonality, the assembler defines similar symbols as the
4312 compiler, depending on the target system selected:
4315 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
4316 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4317 <item><tt/__ATARI__/ - Target system is <tt/atari/
4318 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4319 <item><tt/__BBC__/ - Target system is <tt/bbc/
4320 <item><tt/__C128__/ - Target system is <tt/c128/
4321 <item><tt/__C16__/ - Target system is <tt/c16/
4322 <item><tt/__C64__/ - Target system is <tt/c64/
4323 <item><tt/__CBM__/ - Target is a Commodore system
4324 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4325 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4326 <item><tt/__GEOS__/ - Target system is <tt/geos/
4327 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4328 <item><tt/__NES__/ - Target system is <tt/nes/
4329 <item><tt/__PET__/ - Target system is <tt/pet/
4330 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4331 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4332 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4336 <sect>Structs and unions<label id="structs"><p>
4338 <sect1>Structs and unions Overview<p>
4340 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4341 are to some degree comparable to their C counterparts. Both have a list of
4342 members. Each member allocates storage and may optionally have a name, which,
4343 in case of a struct, is the offset from the beginning and, in case of a union,
4347 <sect1>Declaration<p>
4349 Here is an example for a very simple struct with two members and a total size
4359 A union shares the total space between all its members, its size is the same
4360 as that of the largest member.
4362 A struct or union must not necessarily have a name. If it is anonymous, no
4363 local scope is opened, the identifiers used to name the members are placed
4364 into the current scope instead.
4366 A struct may contain unnamed members and definitions of local structs. The
4367 storage allocators may contain a multiplier, as in the example below:
4372 .word 2 ; Allocate two words
4379 <sect1>The <tt/.TAG/ keyword<p>
4381 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4382 for an already defined struct or unions within another struct:
4396 Space for a struct or union may be allocated using the <ref id=".TAG"
4397 name=".TAG"> directive.
4403 Currently, members are just offsets from the start of the struct or union. To
4404 access a field of a struct, the member offset has to be added to the address
4405 of the struct itself:
4408 lda C+Circle::Radius ; Load circle radius into A
4411 This may change in a future version of the assembler.
4414 <sect1>Limitations<p>
4416 Structs and unions are currently implemented as nested symbol tables (in fact,
4417 they were a by-product of the improved scoping rules). Currently, the
4418 assembler has no idea of types. This means that the <ref id=".TAG"
4419 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4420 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4421 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4422 this structure accessible by using the '::' operator.
4426 <sect>Module constructors/destructors<label id="condes"><p>
4428 <em>Note:</em> This section applies mostly to C programs, so the explanation
4429 below uses examples from the C libraries. However, the feature may also be
4430 useful for assembler programs.
4433 <sect1>Module constructors/destructors Overview<p>
4435 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4436 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4437 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
4438 special way. The linker is able to generate tables with all functions of a
4439 specific type. Such a table will <em>only</em> include symbols from object
4440 files that are linked into a specific executable. This may be used to add
4441 initialization and cleanup code for library modules, or a table of interrupt
4444 The C heap functions are an example where module initialization code is used.
4445 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4446 variables that contain the start and the end of the heap, pointers to the free
4447 list and so on. Since the end of the heap depends on the size and start of the
4448 stack, it must be initialized at runtime. However, initializing these
4449 variables for programs that do not use the heap are a waste of time and
4452 So the central module defines a function that contains initialization code and
4453 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4454 this module is added to an executable by the linker, the initialization
4455 function will be placed into the table of constructors by the linker. The C
4456 startup code will call all constructors before <tt/main/ and all destructors
4457 after <tt/main/, so without any further work, the heap initialization code is
4458 called once the module is linked in.
4460 While it would be possible to add explicit calls to initialization functions
4461 in the startup code, the new approach has several advantages:
4465 If a module is not included, the initialization code is not linked in and not
4466 called. So you don't pay for things you don't need.
4469 Adding another library that needs initialization does not mean that the
4470 startup code has to be changed. Before we had module constructors and
4471 destructors, the startup code for all systems had to be adjusted to call the
4472 new initialization code.
4475 The feature saves memory: Each additional initialization function needs just
4476 two bytes in the table (a pointer to the function).
4481 <sect1>Calling order<p>
4483 The symbols are sorted in increasing priority order by the linker when using
4484 one of the builtin linker configurations, so the functions with lower
4485 priorities come first and are followed by those with higher priorities. The C
4486 library runtime subroutine that walks over the function tables calls the
4487 functions starting from the top of the table - which means that functions with
4488 a high priority are called first.
4490 So when using the C runtime, functions are called with high priority functions
4491 first, followed by low priority functions.
4496 When using these special symbols, please take care of the following:
4501 The linker will only generate function tables, it will not generate code to
4502 call these functions. If you're using the feature in some other than the
4503 existing C environments, you have to write code to call all functions in a
4504 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4505 in the C runtime for an example on how to do this.
4508 The linker will only add addresses of functions that are in modules linked to
4509 the executable. This means that you have to be careful where to place the
4510 condes functions. If initialization or an irq handler is needed for a group of
4511 functions, be sure to place the function into a module that is linked in
4512 regardless of which function is called by the user.
4515 The linker will generate the tables only when requested to do so by the
4516 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4517 be requested separately.
4520 Constructors and destructors may have priorities. These priorities determine
4521 the order of the functions in the table. If your initialization or cleanup code
4522 does depend on other initialization or cleanup code, you have to choose the
4523 priority for the functions accordingly.
4526 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4527 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4528 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4529 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4530 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4531 (interruptor). The linker generates a separate table for each type on request.
4536 <sect>Porting sources from other assemblers<p>
4538 Sometimes it is necessary to port code written for older assemblers to ca65.
4539 In some cases, this can be done without any changes to the source code by
4540 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4541 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4544 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4545 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4546 done by the linker. Most other assemblers generate absolute code, placement is
4547 done within the assembler and there is no external linker.
4549 In general it is not a good idea to write new code using the emulation
4550 features of the assembler, but there may be situations where even this rule is
4555 You need to use some of the ca65 emulation features to simulate the behaviour
4556 of such simple assemblers.
4559 <item>Prepare your sourcecode like this:
4562 ; if you want TASS style labels without colons
4563 .feature labels_without_colons
4565 ; if you want TASS style character constants
4566 ; ("a" instead of the default 'a')
4567 .feature loose_char_term
4569 .word *+2 ; the cbm load address
4574 notice that the two emulation features are mostly useful for porting
4575 sources originally written in/for TASS, they are not needed for the
4576 actual "simple assembler operation" and are not recommended if you are
4577 writing new code from scratch.
4579 <item>Replace all program counter assignments (which are not possible in ca65
4580 by default, and the respective emulation feature works different from what
4581 you'd expect) by another way to skip to memory locations, for example the
4582 <tt><ref id=".RES" name=".RES"></tt> directive.
4586 .res $2000-* ; reserve memory up to $2000
4589 Please note that other than the original TASS, ca65 can never move the program
4590 counter backwards - think of it as if you are assembling to disk with TASS.
4592 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4593 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4594 of <tt/.goto/, everything involving loops must be replaced by
4595 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4597 <item>To assemble code to a different address than it is executed at, use the
4598 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4599 <tt/.offs/-constructs.
4606 .reloc ; back to normal
4609 <item>Then assemble like this:
4612 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4615 Note that you need to use the actual start address minus two, since two bytes
4616 are used for the cbm load address.
4621 <sect>Bugs/Feedback<p>
4623 If you have problems using the assembler, if you find any bugs, or if
4624 you're doing something interesting with the assembler, I would be glad to
4625 hear from you. Feel free to contact me by email
4626 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4632 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4633 Bassewitz. For usage of the binaries and/or sources the following
4634 conditions do apply:
4636 This software is provided 'as-is', without any expressed or implied
4637 warranty. In no event will the authors be held liable for any damages
4638 arising from the use of this software.
4640 Permission is granted to anyone to use this software for any purpose,
4641 including commercial applications, and to alter it and redistribute it
4642 freely, subject to the following restrictions:
4645 <item> The origin of this software must not be misrepresented; you must not
4646 claim that you wrote the original software. If you use this software
4647 in a product, an acknowledgment in the product documentation would be
4648 appreciated but is not required.
4649 <item> Altered source versions must be plainly marked as such, and must not
4650 be misrepresented as being the original software.
4651 <item> This notice may not be removed or altered from any source