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>.BANK</tt><label id=".BANK"><p>
1280 The <tt/.BANK/ function is used to support systems with banked memory. The
1281 argument is an expression with exactly one segment reference - usually a
1282 label. The function result is the value of the <tt/bank/ attribute assigned
1283 to the run memory area of the segment. Please see the linker documentation
1284 for more information about memory areas and their attributes.
1286 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1287 containing specific data is available.
1289 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1290 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1291 name=".LOBYTE"></tt> or similar functions to address just part of it.
1293 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1294 an expression containing <tt/.BANK/ can never be used where a constant known
1295 result is expected (for example with <tt/.RES/).
1312 .byte <.BANK (banked_func_1)
1315 .byte <.BANK (banked_func_2)
1321 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1323 The function returns the bank byte (that is, bits 16-23) of its argument.
1324 It works identical to the '^' operator.
1326 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1327 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1330 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1332 Builtin function. The function evaluates its argument in braces and yields
1333 "false" if the argument is non blank (there is an argument), and "true" if
1334 there is no argument. The token list that makes up the function argument
1335 may optionally be enclosed in curly braces. This allows the inclusion of
1336 tokens that would otherwise terminate the list (the closing right
1337 parenthesis). The curly braces are not considered part of the list, a list
1338 just consisting of curly braces is considered to be empty.
1340 As an example, the <tt/.IFBLANK/ statement may be replaced by
1348 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1350 Builtin string function. The function allows to concatenate a list of string
1351 constants separated by commas. The result is a string constant that is the
1352 concatenation of all arguments. This function is most useful in macros and
1353 when used together with the <tt/.STRING/ builtin function. The function may
1354 be used in any case where a string constant is expected.
1359 .include .concat ("myheader", ".", "inc")
1362 This is the same as the command
1365 .include "myheader.inc"
1369 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1371 Builtin function. The function evaluates its argument in braces and
1372 yields "true" if the argument is a constant expression (that is, an
1373 expression that yields a constant value at assembly time) and "false"
1374 otherwise. As an example, the .IFCONST statement may be replaced by
1381 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1383 The function returns the high byte (that is, bits 8-15) of its argument.
1384 It works identical to the '>' operator.
1386 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1387 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1390 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1392 The function returns the high word (that is, bits 16-31) of its argument.
1394 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1397 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1399 The function expects a string as its argument, and converts this argument
1400 into an identifier. If the string starts with the current <tt/<ref
1401 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1402 identifier, otherwise it will be converted into a normal identifier.
1407 .macro makelabel arg1, arg2
1408 .ident (.concat (arg1, arg2)):
1411 makelabel "foo", "bar"
1413 .word foobar ; Valid label
1417 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1419 Builtin function. Extracts the left part of a given token list.
1424 .LEFT (<int expr>, <token list>)
1427 The first integer expression gives the number of tokens to extract from
1428 the token list. The second argument is the token list itself. The token
1429 list may optionally be enclosed into curly braces. This allows the
1430 inclusion of tokens that would otherwise terminate the list (the closing
1431 right paren in the given case).
1435 To check in a macro if the given argument has a '#' as first token
1436 (immediate addressing mode), use something like this:
1441 .if (.match (.left (1, {arg}), #))
1443 ; ldax called with immediate operand
1451 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1452 name=".RIGHT"></tt> builtin functions.
1455 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1457 The function returns the low byte (that is, bits 0-7) of its argument.
1458 It works identical to the '<' operator.
1460 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1461 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1464 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1466 The function returns the low word (that is, bits 0-15) of its argument.
1468 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1471 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1473 Builtin function. Matches two token lists against each other. This is
1474 most useful within macros, since macros are not stored as strings, but
1480 .MATCH(<token list #1>, <token list #2>)
1483 Both token list may contain arbitrary tokens with the exception of the
1484 terminator token (comma resp. right parenthesis) and
1491 The token lists may optionally be enclosed into curly braces. This allows
1492 the inclusion of tokens that would otherwise terminate the list (the closing
1493 right paren in the given case). Often a macro parameter is used for any of
1496 Please note that the function does only compare tokens, not token
1497 attributes. So any number is equal to any other number, regardless of the
1498 actual value. The same is true for strings. If you need to compare tokens
1499 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1500 name=".XMATCH"></tt> function.
1504 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1505 while honoring the sign bit. The builtin processor instructions will allow
1506 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1507 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1508 to check for this and print and error for invalid calls.
1513 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1514 .error "Syntax error"
1517 cmp #$80 ; Bit 7 into carry
1518 lsr a ; Shift carry into bit 7
1523 The macro will only accept no arguments, or one argument that must be the
1524 reserved keyword "A".
1526 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1529 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1531 Builtin function. The result is the larger of two values.
1536 .MAX (<value #1>, <value #2>)
1542 ; Reserve space for the larger of two data blocks
1543 savearea: .max (.sizeof (foo), .sizeof (bar))
1546 See: <tt><ref id=".MIN" name=".MIN"></tt>
1549 <sect1><tt>.MID</tt><label id=".MID"><p>
1551 Builtin function. Takes a starting index, a count and a token list as
1552 arguments. Will return part of the token list.
1557 .MID (<int expr>, <int expr>, <token list>)
1560 The first integer expression gives the starting token in the list (the first
1561 token has index 0). The second integer expression gives the number of tokens
1562 to extract from the token list. The third argument is the token list itself.
1563 The token list may optionally be enclosed into curly braces. This allows the
1564 inclusion of tokens that would otherwise terminate the list (the closing
1565 right paren in the given case).
1569 To check in a macro if the given argument has a '<tt/#/' as first token
1570 (immediate addressing mode), use something like this:
1575 .if (.match (.mid (0, 1, {arg}), #))
1577 ; ldax called with immediate operand
1585 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1586 name=".RIGHT"></tt> builtin functions.
1589 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1591 Builtin function. The result is the smaller of two values.
1596 .MIN (<value #1>, <value #2>)
1602 ; Reserve space for some data, but 256 bytes minimum
1603 savearea: .min (.sizeof (foo), 256)
1606 See: <tt><ref id=".MAX" name=".MAX"></tt>
1609 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1611 Builtin function. The function expects an identifier as argument in braces.
1612 The argument is evaluated, and the function yields "true" if the identifier
1613 is a symbol that has already been referenced somewhere in the source file up
1614 to the current position. Otherwise the function yields false. As an example,
1615 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1621 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1624 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1626 Builtin function. Extracts the right part of a given token list.
1631 .RIGHT (<int expr>, <token list>)
1634 The first integer expression gives the number of tokens to extract from the
1635 token list. The second argument is the token list itself. The token list
1636 may optionally be enclosed into curly braces. This allows the inclusion of
1637 tokens that would otherwise terminate the list (the closing right paren in
1640 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1641 name=".MID"></tt> builtin functions.
1644 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1646 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1647 argument can be a struct/union, a struct member, a procedure, or a label. In
1648 case of a procedure or label, its size is defined by the amount of data
1649 placed in the segment where the label is relative to. If a line of code
1650 switches segments (for example in a macro) data placed in other segments
1651 does not count for the size.
1653 Please note that a symbol or scope must exist, before it is used together with
1654 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1655 A scope has preference over a symbol with the same name, so if the last part
1656 of a name represents both, a scope and a symbol, the scope is chosen over the
1659 After the following code:
1662 .struct Point ; Struct size = 4
1667 P: .tag Point ; Declare a point
1668 @P: .tag Point ; Declare another point
1680 .data ; Segment switch!!!
1686 <tag><tt/.sizeof(Point)/</tag>
1687 will have the value 4, because this is the size of struct <tt/Point/.
1689 <tag><tt/.sizeof(Point::xcoord)/</tag>
1690 will have the value 2, because this is the size of the member <tt/xcoord/
1691 in struct <tt/Point/.
1693 <tag><tt/.sizeof(P)/</tag>
1694 will have the value 4, this is the size of the data declared on the same
1695 source line as the label <tt/P/, which is in the same segment that <tt/P/
1698 <tag><tt/.sizeof(@P)/</tag>
1699 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1700 does also work for cheap local symbols.
1702 <tag><tt/.sizeof(Code)/</tag>
1703 will have the value 3, since this is amount of data emitted into the code
1704 segment, the segment that was active when <tt/Code/ was entered. Note that
1705 this value includes the amount of data emitted in child scopes (in this
1706 case <tt/Code::Inner/).
1708 <tag><tt/.sizeof(Code::Inner)/</tag>
1709 will have the value 1 as expected.
1711 <tag><tt/.sizeof(Data)/</tag>
1712 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1713 the segment is switched after entry, this data is emitted into another
1718 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1720 Builtin function. The function accepts a string and an index as
1721 arguments and returns the value of the character at the given position
1722 as an integer value. The index is zero based.
1728 ; Check if the argument string starts with '#'
1729 .if (.strat (Arg, 0) = '#')
1736 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1738 Builtin function. It expects a format string as first argument. The number
1739 and type of the following arguments depend on the format string. The format
1740 string is similar to the one of the C <tt/printf/ function. Missing things
1741 are: Length modifiers, variable width.
1743 The result of the function is a string.
1750 ; Generate an identifier:
1751 .ident (.sprintf ("%s%03d", "label", num)):
1755 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1757 Builtin function. The function accepts an argument in braces and converts
1758 this argument into a string constant. The argument may be an identifier, or
1759 a constant numeric value.
1761 Since you can use a string in the first place, the use of the function may
1762 not be obvious. However, it is useful in macros, or more complex setups.
1767 ; Emulate other assemblers:
1769 .segment .string(name)
1774 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1776 Builtin function. The function accepts a string argument in braces and
1777 evaluates to the length of the string.
1781 The following macro encodes a string as a pascal style string with
1782 a leading length byte.
1786 .byte .strlen(Arg), Arg
1791 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1793 Builtin function. The function accepts a token list in braces. The function
1794 result is the number of tokens given as argument. The token list may
1795 optionally be enclosed into curly braces which are not considered part of
1796 the list and not counted. Enclosement in curly braces allows the inclusion
1797 of tokens that would otherwise terminate the list (the closing right paren
1802 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1803 with the normal 6502 instructions). To translate it into two separate 8 bit
1804 load instructions, the '#' token has to get stripped from the argument:
1808 .if (.match (.mid (0, 1, {arg}), #))
1809 ; ldax called with immediate operand
1810 lda #<(.right (.tcount ({arg})-1, {arg}))
1811 ldx #>(.right (.tcount ({arg})-1, {arg}))
1819 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1821 Builtin function. Matches two token lists against each other. This is
1822 most useful within macros, since macros are not stored as strings, but
1828 .XMATCH(<token list #1>, <token list #2>)
1831 Both token list may contain arbitrary tokens with the exception of the
1832 terminator token (comma resp. right parenthesis) and
1839 The token lists may optionally be enclosed into curly braces. This allows
1840 the inclusion of tokens that would otherwise terminate the list (the closing
1841 right paren in the given case). Often a macro parameter is used for any of
1844 The function compares tokens <em/and/ token values. If you need a function
1845 that just compares the type of tokens, have a look at the <tt><ref
1846 id=".MATCH" name=".MATCH"></tt> function.
1848 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1852 <sect>Control commands<label id="control-commands"><p>
1854 Here's a list of all control commands and a description, what they do:
1857 <sect1><tt>.A16</tt><label id=".A16"><p>
1859 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1861 Note: This command will not emit any code, it will tell the assembler to
1862 create 16 bit operands for immediate accumulator addressing mode.
1864 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1867 <sect1><tt>.A8</tt><label id=".A8"><p>
1869 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1871 Note: This command will not emit any code, it will tell the assembler to
1872 create 8 bit operands for immediate accu addressing mode.
1874 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1877 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1879 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1880 may be used for better readability if the data words are address values. In
1881 65816 mode, the address is forced to be 16 bit wide to fit into the current
1882 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1883 must be followed by a sequence of (not necessarily constant) expressions.
1888 .addr $0D00, $AF13, _Clear
1891 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1895 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1897 Align data to a given boundary. The command expects a constant integer
1898 argument in the range 1 ... 65536, plus an optional second argument
1899 in byte range. If there is a second argument, it is used as fill value,
1900 otherwise the value defined in the linker configuration file is used
1901 (the default for this value is zero).
1903 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1904 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1905 number of bytes, since that would break address calculations within the
1906 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1907 of the alignment, because that allows the number of fill bytes to be
1908 calculated in advance by the assembler. You are therefore required to
1909 specify a matching alignment for the segment in the linker config. The
1910 linker will output a warning if the alignment of the segment is less than
1911 what is necessary to have a correct alignment in the object file.
1919 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1920 commands with different arguments. To allow the assembler to calculate the
1921 number of fill bytes in advance, the alignment of the segment must be a
1922 multiple of each of the alignment factors. This may result in unexpectedly
1923 large alignments for the segment within the module.
1934 For the assembler to be able to align correctly, the segment must be aligned
1935 to the least common multiple of 15 and 18 which is 90. The assembler will
1936 calculate this automatically and will mark the segment with this value.
1938 Unfortunately, the combined alignment may get rather large without the user
1939 knowing about it, wasting space in the final executable. If we add another
1940 alignment to the example above
1951 the assembler will force a segment alignment to the least common multiple of
1952 15, 18 and 251 - which is 22590. To protect the user against errors, the
1953 assembler will issue a warning when the combined alignment exceeds 256. The
1954 command line option <tt><ref id="option--large-alignment"
1955 name="--large-alignment"></tt> will disable this warning.
1957 Please note that with alignments that are a power of two (which were the
1958 only alignments possible in older versions of the assembler), the problem is
1959 less severe, because the least common multiple of powers to the same base is
1960 always the larger one.
1964 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1966 Define a string with a trailing zero.
1971 Msg: .asciiz "Hello world"
1974 This will put the string "Hello world" followed by a binary zero into
1975 the current segment. There may be more strings separated by commas, but
1976 the binary zero is only appended once (after the last one).
1979 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1981 Add an assertion. The command is followed by an expression, an action
1982 specifier, and an optional message that is output in case the assertion
1983 fails. If no message was given, the string "Assertion failed" is used. The
1984 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
1985 <tt/lderror/. In the former two cases, the assertion is evaluated by the
1986 assembler if possible, and in any case, it's also passed to the linker in
1987 the object file (if one is generated). The linker will then evaluate the
1988 expression when segment placement has been done.
1993 .assert * = $8000, error, "Code not at $8000"
1996 The example assertion will check that the current location is at $8000,
1997 when the output file is written, and abort with an error if this is not
1998 the case. More complex expressions are possible. The action specifier
1999 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2000 an error message. In the latter case, generation of the output file is
2001 suppressed in both the assembler and linker.
2004 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2006 Is followed by a plus or a minus character. When switched on (using a
2007 +), undefined symbols are automatically marked as import instead of
2008 giving errors. When switched off (which is the default so this does not
2009 make much sense), this does not happen and an error message is
2010 displayed. The state of the autoimport flag is evaluated when the
2011 complete source was translated, before outputting actual code, so it is
2012 <em/not/ possible to switch this feature on or off for separate sections
2013 of code. The last setting is used for all symbols.
2015 You should probably not use this switch because it delays error
2016 messages about undefined symbols until the link stage. The cc65
2017 compiler (which is supposed to produce correct assembler code in all
2018 circumstances, something which is not true for most assembler
2019 programmers) will insert this command to avoid importing each and every
2020 routine from the runtime library.
2025 .autoimport + ; Switch on auto import
2028 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2030 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2031 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2032 the operator '^' prepended to each expression in its list.
2037 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2039 TableLookupLo: .lobytes MyTable
2040 TableLookupHi: .hibytes MyTable
2041 TableLookupBank: .bankbytes MyTable
2044 which is equivalent to
2047 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2048 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2049 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2052 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2053 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2054 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2057 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2059 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2060 so this is a shortcut for
2066 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2069 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2071 Define byte sized data. Must be followed by a sequence of (byte ranged)
2072 expressions or strings.
2078 .byt "world", $0D, $00
2082 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2084 Switch on or off case sensitivity on identifiers. The default is off
2085 (that is, identifiers are case sensitive), but may be changed by the
2086 -i switch on the command line.
2087 The command must be followed by a '+' or '-' character to switch the
2088 option on or off respectively.
2093 .case - ; Identifiers are not case sensitive
2097 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2099 Apply a custom mapping for characters. The command is followed by two
2100 numbers in the range 1..255. The first one is the index of the source
2101 character, the second one is the mapping. The mapping applies to all
2102 character and string constants when they generate output, and overrides
2103 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2104 command line switch.
2109 .charmap $41, $61 ; Map 'A' to 'a'
2113 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2115 Switch to the CODE segment. The name of the CODE segment is always
2116 "CODE", so this is a shortcut for
2122 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2125 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2127 Export a symbol and mark it in a special way. The linker is able to build
2128 tables of all such symbols. This may be used to automatically create a list
2129 of functions needed to initialize linked library modules.
2131 Note: The linker has a feature to build a table of marked routines, but it
2132 is your code that must call these routines, so just declaring a symbol with
2133 <tt/.CONDES/ does nothing by itself.
2135 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2136 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2137 is implied by <tt/.CONDES/.
2139 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2140 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2141 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2142 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2143 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2144 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2145 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2147 After the type, an optional priority may be specified. Higher numeric values
2148 mean higher priority. If no priority is given, the default priority of 7 is
2149 used. Be careful when assigning priorities to your own module constructors
2150 so they won't interfere with the ones in the cc65 library.
2155 .condes ModuleInit, constructor
2156 .condes ModInit, 0, 16
2159 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2160 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2161 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2162 name="Module constructors/destructors"> explaining the feature in more
2166 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2168 Export a symbol and mark it as a module constructor. This may be used
2169 together with the linker to build a table of constructor subroutines that
2170 are called by the startup code.
2172 Note: The linker has a feature to build a table of marked routines, but it
2173 is your code that must call these routines, so just declaring a symbol as
2174 constructor does nothing by itself.
2176 A constructor is always exported as an absolute (16 bit) symbol. You don't
2177 need to use an additional <tt/.export/ statement, this is implied by
2178 <tt/.constructor/. It may have an optional priority that is separated by a
2179 comma. Higher numeric values mean a higher priority. If no priority is
2180 given, the default priority of 7 is used. Be careful when assigning
2181 priorities to your own module constructors so they won't interfere with the
2182 ones in the cc65 library.
2187 .constructor ModuleInit
2188 .constructor ModInit, 16
2191 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2192 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2193 <ref id="condes" name="Module constructors/destructors"> explaining the
2194 feature in more detail.
2197 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2199 Switch to the DATA segment. The name of the DATA segment is always
2200 "DATA", so this is a shortcut for
2206 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2209 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2211 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2212 create word sized data in native 65XX format). Must be followed by a
2213 sequence of (word ranged) expressions.
2221 This will emit the bytes
2227 into the current segment in that order.
2230 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2232 Switch on or off debug info generation. The default is off (that is,
2233 the object file will not contain debug infos), but may be changed by the
2234 -g switch on the command line.
2235 The command must be followed by a '+' or '-' character to switch the
2236 option on or off respectively.
2241 .debuginfo + ; Generate debug info
2245 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2247 Start a define style macro definition. The command is followed by an
2248 identifier (the macro name) and optionally by a list of formal arguments
2250 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2251 section <ref id="macros" name="Macros">.
2254 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2256 Delete a classic macro (defined with <tt><ref id=".MACRO"
2257 name=".MACRO"></tt>) . The command is followed by the name of an
2258 existing macro. Its definition will be deleted together with the name.
2259 If necessary, another macro with this name may be defined later.
2261 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2262 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2263 <tt><ref id=".MACRO" name=".MACRO"></tt>
2265 See also section <ref id="macros" name="Macros">.
2268 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2270 Builtin function. The function expects an identifier as argument in braces.
2271 The argument is evaluated, and the function yields "true" if the identifier
2272 is a symbol that is already defined somewhere in the source file up to the
2273 current position. Otherwise the function yields false. As an example, the
2274 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2281 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2283 Export a symbol and mark it as a module destructor. This may be used
2284 together with the linker to build a table of destructor subroutines that
2285 are called by the startup code.
2287 Note: The linker has a feature to build a table of marked routines, but it
2288 is your code that must call these routines, so just declaring a symbol as
2289 constructor does nothing by itself.
2291 A destructor is always exported as an absolute (16 bit) symbol. You don't
2292 need to use an additional <tt/.export/ statement, this is implied by
2293 <tt/.destructor/. It may have an optional priority that is separated by a
2294 comma. Higher numerical values mean a higher priority. If no priority is
2295 given, the default priority of 7 is used. Be careful when assigning
2296 priorities to your own module destructors so they won't interfere with the
2297 ones in the cc65 library.
2302 .destructor ModuleDone
2303 .destructor ModDone, 16
2306 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2307 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2308 section <ref id="condes" name="Module constructors/destructors"> explaining
2309 the feature in more detail.
2312 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2314 Define dword sized data (4 bytes) Must be followed by a sequence of
2320 .dword $12344512, $12FA489
2324 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2326 Conditional assembly: Reverse the current condition.
2329 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2331 Conditional assembly: Reverse current condition and test a new one.
2334 <sect1><tt>.END</tt><label id=".END"><p>
2336 Forced end of assembly. Assembly stops at this point, even if the command
2337 is read from an include file.
2340 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2342 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2345 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2347 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2348 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2351 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2353 Marks the end of a macro definition.
2355 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2356 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2357 <tt><ref id=".MACRO" name=".MACRO"></tt>
2359 See also section <ref id="macros" name="Macros">.
2362 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2364 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2367 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2369 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2372 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2374 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2377 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2379 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2380 command and the separate section named <ref id="structs" name=""Structs
2384 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2386 Start an enumeration. This directive is very similar to the C <tt/enum/
2387 keyword. If a name is given, a new scope is created for the enumeration,
2388 otherwise the enumeration members are placed in the enclosing scope.
2390 In the enumeration body, symbols are declared. The first symbol has a value
2391 of zero, and each following symbol will get the value of the preceding plus
2392 one. This behaviour may be overridden by an explicit assignment. Two symbols
2393 may have the same value.
2405 Above example will create a new scope named <tt/errorcodes/ with three
2406 symbols in it that get the values 0, 1 and 2 respectively. Another way
2407 to write this would have been:
2417 Please note that explicit scoping must be used to access the identifiers:
2420 .word errorcodes::no_error
2423 A more complex example:
2432 EWOULDBLOCK = EAGAIN
2436 In this example, the enumeration does not have a name, which means that the
2437 members will be visible in the enclosing scope and can be used in this scope
2438 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2439 The value for the following members is incremented by one, so <tt/EOK/ would
2440 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2441 override for the value using an already defined symbol.
2444 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2446 Force an assembly error. The assembler will output an error message
2447 preceded by "User error". Assembly is continued but no object file will
2450 This command may be used to check for initial conditions that must be
2451 set before assembling a source file.
2461 .error "Must define foo or bar!"
2465 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2466 <tt><ref id=".OUT" name=".OUT"></tt>,
2467 <tt><ref id=".WARNING" name=".WARNING"></tt>
2470 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2472 Abort a macro expansion immediately. This command is often useful in
2475 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2476 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2477 <tt><ref id=".MACRO" name=".MACRO"></tt>
2479 See also section <ref id="macros" name="Macros">.
2482 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2484 Make symbols accessible from other modules. Must be followed by a comma
2485 separated list of symbols to export, with each one optionally followed by an
2486 address specification and (also optional) an assignment. Using an additional
2487 assignment in the export statement allows to define and export a symbol in
2488 one statement. The default is to export the symbol with the address size it
2489 actually has. The assembler will issue a warning, if the symbol is exported
2490 with an address size smaller than the actual address size.
2497 .export foobar: far = foo * bar
2498 .export baz := foobar, zap: far = baz - bar
2501 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2504 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2507 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2509 Make symbols accessible from other modules. Must be followed by a comma
2510 separated list of symbols to export. The exported symbols are explicitly
2511 marked as zero page symbols. An assignment may be included in the
2512 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2519 .exportzp baz := $02
2522 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2525 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2527 Define far (24 bit) address data. The command must be followed by a
2528 sequence of (not necessarily constant) expressions.
2533 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2536 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2539 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2541 Force an assembly error and terminate assembly. The assembler will output an
2542 error message preceded by "User error" and will terminate assembly
2545 This command may be used to check for initial conditions that must be
2546 set before assembling a source file.
2556 .fatal "Must define foo or bar!"
2560 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2561 <tt><ref id=".OUT" name=".OUT"></tt>,
2562 <tt><ref id=".WARNING" name=".WARNING"></tt>
2565 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2567 This directive may be used to enable one or more compatibility features
2568 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2569 possible, it may be useful when porting sources written for other
2570 assemblers. There is no way to switch a feature off, once you have
2571 enabled it, so using
2577 will enable the feature until end of assembly is reached.
2579 The following features are available:
2583 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2585 Accept the at character (`@') as a valid character in identifiers. The
2586 at character is not allowed to start an identifier, even with this
2589 <tag><tt>c_comments</tt></tag>
2591 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2592 comment terminators. Note that C comments may not be nested. There's also a
2593 pitfall when using C like comments: All statements must be terminated by
2594 "end-of-line". Using C like comments, it is possible to hide the newline,
2595 which results in error messages. See the following non working example:
2598 lda #$00 /* This comment hides the newline
2602 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2604 Accept the dollar sign (`$') as a valid character in identifiers. The
2605 dollar character is not allowed to start an identifier, even with this
2608 <tag><tt>dollar_is_pc</tt></tag>
2610 The dollar sign may be used as an alias for the star (`*'), which
2611 gives the value of the current PC in expressions.
2612 Note: Assignment to the pseudo variable is not allowed.
2614 <tag><tt>labels_without_colons</tt></tag>
2616 Allow labels without a trailing colon. These labels are only accepted,
2617 if they start at the beginning of a line (no leading white space).
2619 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2621 Accept the dot (`.') as the first character of an identifier. This may be
2622 used for example to create macro names that start with a dot emulating
2623 control directives of other assemblers. Note however, that none of the
2624 reserved keywords built into the assembler, that starts with a dot, may be
2625 overridden. When using this feature, you may also get into trouble if
2626 later versions of the assembler define new keywords starting with a dot.
2628 <tag><tt>loose_char_term</tt></tag>
2630 Accept single quotes as well as double quotes as terminators for char
2633 <tag><tt>loose_string_term</tt></tag>
2635 Accept single quotes as well as double quotes as terminators for string
2638 <tag><tt>missing_char_term</tt></tag>
2640 Accept single quoted character constants where the terminating quote is
2645 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2646 loose_string_term/, since in this case the input would be ambiguous.
2648 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2650 This feature makes relocatable/absolute mode local to the current segment.
2651 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2652 effect will only enable absolute mode for the current segment. Dito for
2653 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2655 <tag><tt>pc_assignment</tt></tag>
2657 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2658 is enabled). Such an assignment is handled identical to the <tt><ref
2659 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2660 removing the lines with the assignments may also be an option when porting
2661 code written for older assemblers).
2663 <tag><tt>ubiquitous_idents</tt></tag>
2665 Allow the use of instructions names as names for macros and symbols. This
2666 makes it possible to "overload" instructions by defining a macro with the
2667 same name. This does also make it possible to introduce hard to find errors
2668 in your code, so be careful!
2672 It is also possible to specify features on the command line using the
2673 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2674 This is useful when translating sources written for older assemblers, when
2675 you don't want to change the source code.
2677 As an example, to translate sources written for Andre Fachats xa65
2678 assembler, the features
2681 labels_without_colons, pc_assignment, loose_char_term
2684 may be helpful. They do not make ca65 completely compatible, so you may not
2685 be able to translate the sources without changes, even when enabling these
2686 features. However, I have found several sources that translate without
2687 problems when enabling these features on the command line.
2690 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2692 Insert an option string into the object file. There are two forms of
2693 this command, one specifies the option by a keyword, the second
2694 specifies it as a number. Since usage of the second one needs knowledge
2695 of the internal encoding, its use is not recommended and I will only
2696 describe the first form here.
2698 The command is followed by one of the keywords
2706 a comma and a string. The option is written into the object file
2707 together with the string value. This is currently unidirectional and
2708 there is no way to actually use these options once they are in the
2714 .fileopt comment, "Code stolen from my brother"
2715 .fileopt compiler, "BASIC 2.0"
2716 .fopt author, "J. R. User"
2720 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2722 Import an absolute symbol from another module. The command is followed by a
2723 comma separated list of symbols to import. The command is similar to <tt>
2724 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2725 written to the generated object file, even if the symbol is never referenced
2726 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2727 references for unused symbols).
2732 .forceimport needthisone, needthistoo
2735 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2738 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2740 Declare symbols as global. Must be followed by a comma separated list of
2741 symbols to declare. Symbols from the list, that are defined somewhere in the
2742 source, are exported, all others are imported. Additional <tt><ref
2743 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2744 name=".EXPORT"></tt> commands for the same symbol are allowed.
2753 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2755 Declare symbols as global. Must be followed by a comma separated list of
2756 symbols to declare. Symbols from the list, that are defined somewhere in the
2757 source, are exported, all others are imported. Additional <tt><ref
2758 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2759 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2760 in the list are explicitly marked as zero page symbols.
2768 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2770 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2771 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2772 the operator '>' prepended to each expression in its list.
2777 .lobytes $1234, $2345, $3456, $4567
2778 .hibytes $fedc, $edcb, $dcba, $cba9
2781 which is equivalent to
2784 .byte $34, $45, $56, $67
2785 .byte $fe, $ed, $dc, $cb
2791 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2793 TableLookupLo: .lobytes MyTable
2794 TableLookupHi: .hibytes MyTable
2797 which is equivalent to
2800 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2801 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2804 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2805 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2806 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2809 <sect1><tt>.I16</tt><label id=".I16"><p>
2811 Valid only in 65816 mode. Switch the index registers to 16 bit.
2813 Note: This command will not emit any code, it will tell the assembler to
2814 create 16 bit operands for immediate operands.
2816 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2817 name=".SMART"></tt> commands.
2820 <sect1><tt>.I8</tt><label id=".I8"><p>
2822 Valid only in 65816 mode. Switch the index registers to 8 bit.
2824 Note: This command will not emit any code, it will tell the assembler to
2825 create 8 bit operands for immediate operands.
2827 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2828 name=".SMART"></tt> commands.
2831 <sect1><tt>.IF</tt><label id=".IF"><p>
2833 Conditional assembly: Evaluate an expression and switch assembler output
2834 on or off depending on the expression. The expression must be a constant
2835 expression, that is, all operands must be defined.
2837 A expression value of zero evaluates to FALSE, any other value evaluates
2841 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2843 Conditional assembly: Check if there are any remaining tokens in this line,
2844 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2845 condition is not true, further lines are not assembled until an <tt><ref
2846 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2847 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2849 This command is often used to check if a macro parameter was given. Since an
2850 empty macro parameter will evaluate to nothing, the condition will evaluate
2851 to FALSE if an empty parameter was given.
2865 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2868 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2870 Conditional assembly: Evaluate an expression and switch assembler output
2871 on or off depending on the constness of the expression.
2873 A const expression evaluates to to TRUE, a non const expression (one
2874 containing an imported or currently undefined symbol) evaluates to
2877 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2880 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2882 Conditional assembly: Check if a symbol is defined. Must be followed by
2883 a symbol name. The condition is true if the the given symbol is already
2884 defined, and false otherwise.
2886 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2889 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2891 Conditional assembly: Check if there are any remaining tokens in this line,
2892 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2893 condition is not true, further lines are not assembled until an <tt><ref
2894 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2895 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2897 This command is often used to check if a macro parameter was given.
2898 Since an empty macro parameter will evaluate to nothing, the condition
2899 will evaluate to FALSE if an empty parameter was given.
2912 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2915 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2917 Conditional assembly: Check if a symbol is defined. Must be followed by
2918 a symbol name. The condition is true if the the given symbol is not
2919 defined, and false otherwise.
2921 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2924 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2926 Conditional assembly: Check if a symbol is referenced. Must be followed
2927 by a symbol name. The condition is true if if the the given symbol was
2928 not referenced before, and false otherwise.
2930 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2933 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2935 Conditional assembly: Check if the assembler is currently in 6502 mode
2936 (see <tt><ref id=".P02" name=".P02"></tt> command).
2939 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2941 Conditional assembly: Check if the assembler is currently in 65816 mode
2942 (see <tt><ref id=".P816" name=".P816"></tt> command).
2945 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2947 Conditional assembly: Check if the assembler is currently in 65C02 mode
2948 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2951 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2953 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2954 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2957 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2959 Conditional assembly: Check if a symbol is referenced. Must be followed
2960 by a symbol name. The condition is true if if the the given symbol was
2961 referenced before, and false otherwise.
2963 This command may be used to build subroutine libraries in include files
2964 (you may use separate object modules for this purpose too).
2969 .ifref ToHex ; If someone used this subroutine
2970 ToHex: tay ; Define subroutine
2976 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2979 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2981 Import a symbol from another module. The command is followed by a comma
2982 separated list of symbols to import, with each one optionally followed by
2983 an address specification.
2989 .import bar: zeropage
2992 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2995 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2997 Import a symbol from another module. The command is followed by a comma
2998 separated list of symbols to import. The symbols are explicitly imported
2999 as zero page symbols (that is, symbols with values in byte range).
3007 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3010 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3012 Include a file as binary data. The command expects a string argument
3013 that is the name of a file to include literally in the current segment.
3014 In addition to that, a start offset and a size value may be specified,
3015 separated by commas. If no size is specified, all of the file from the
3016 start offset to end-of-file is used. If no start position is specified
3017 either, zero is assumed (which means that the whole file is inserted).
3022 ; Include whole file
3023 .incbin "sprites.dat"
3025 ; Include file starting at offset 256
3026 .incbin "music.dat", $100
3028 ; Read 100 bytes starting at offset 200
3029 .incbin "graphics.dat", 200, 100
3033 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3035 Include another file. Include files may be nested up to a depth of 16.
3044 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3046 Export a symbol and mark it as an interruptor. This may be used together
3047 with the linker to build a table of interruptor subroutines that are called
3050 Note: The linker has a feature to build a table of marked routines, but it
3051 is your code that must call these routines, so just declaring a symbol as
3052 interruptor does nothing by itself.
3054 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3055 need to use an additional <tt/.export/ statement, this is implied by
3056 <tt/.interruptor/. It may have an optional priority that is separated by a
3057 comma. Higher numeric values mean a higher priority. If no priority is
3058 given, the default priority of 7 is used. Be careful when assigning
3059 priorities to your own module constructors so they won't interfere with the
3060 ones in the cc65 library.
3065 .interruptor IrqHandler
3066 .interruptor Handler, 16
3069 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3070 section <ref id="condes" name="Module constructors/destructors"> explaining
3071 the feature in more detail.
3074 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3076 Switch on or off line continuations using the backslash character
3077 before a newline. The option is off by default.
3078 Note: Line continuations do not work in a comment. A backslash at the
3079 end of a comment is treated as part of the comment and does not trigger
3081 The command must be followed by a '+' or '-' character to switch the
3082 option on or off respectively.
3087 .linecont + ; Allow line continuations
3090 #$20 ; This is legal now
3094 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3096 Enable output to the listing. The command must be followed by a boolean
3097 switch ("on", "off", "+" or "-") and will enable or disable listing
3099 The option has no effect if the listing is not enabled by the command line
3100 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3101 to the listing file, if the counter is greater than zero, and suppressed if
3102 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3108 .list on ; Enable listing output
3112 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3114 Set, how many bytes are shown in the listing for one source line. The
3115 default is 12, so the listing will show only the first 12 bytes for any
3116 source line that generates more than 12 bytes of code or data.
3117 The directive needs an argument, which is either "unlimited", or an
3118 integer constant in the range 4..255.
3123 .listbytes unlimited ; List all bytes
3124 .listbytes 12 ; List the first 12 bytes
3125 .incbin "data.bin" ; Include large binary file
3129 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3131 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3132 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3133 the operator '<' prepended to each expression in its list.
3138 .lobytes $1234, $2345, $3456, $4567
3139 .hibytes $fedc, $edcb, $dcba, $cba9
3142 which is equivalent to
3145 .byte $34, $45, $56, $67
3146 .byte $fe, $ed, $dc, $cb
3152 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3154 TableLookupLo: .lobytes MyTable
3155 TableLookupHi: .hibytes MyTable
3158 which is equivalent to
3161 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3162 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3165 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3166 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3167 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3170 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3172 This command may only be used inside a macro definition. It declares a
3173 list of identifiers as local to the macro expansion.
3175 A problem when using macros are labels: Since they don't change their name,
3176 you get a "duplicate symbol" error if the macro is expanded the second time.
3177 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3178 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3181 Some other assemblers start a new lexical block inside a macro expansion.
3182 This has some drawbacks however, since that will not allow <em/any/ symbol
3183 to be visible outside a macro, a feature that is sometimes useful. The
3184 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3185 to address the problem.
3187 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3191 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3193 Defines the character that start "cheap" local labels. You may use one
3194 of '@' and '?' as start character. The default is '@'.
3196 Cheap local labels are labels that are visible only between two non
3197 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3198 using explicit lexical nesting.
3205 Clear: lda #$00 ; Global label
3206 ?Loop: sta Mem,y ; Local label
3210 Sub: ... ; New global label
3211 bne ?Loop ; ERROR: Unknown identifier!
3215 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3217 Insert a predefined macro package. The command is followed by an
3218 identifier specifying the macro package to insert. Available macro
3222 atari Defines the scrcode macro.
3223 cbm Defines the scrcode macro.
3224 cpu Defines constants for the .CPU variable.
3225 generic Defines generic macros like add and sub.
3226 longbranch Defines conditional long jump macros.
3229 Including a macro package twice, or including a macro package that
3230 redefines already existing macros will lead to an error.
3235 .macpack longbranch ; Include macro package
3237 cmp #$20 ; Set condition codes
3238 jne Label ; Jump long on condition
3241 Macro packages are explained in more detail in section <ref
3242 id="macropackages" name="Macro packages">.
3245 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3247 Start a classic macro definition. The command is followed by an identifier
3248 (the macro name) and optionally by a comma separated list of identifiers
3249 that are macro parameters. A macro definition is terminated by <tt><ref
3250 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3255 .macro ldax arg ; Define macro ldax
3260 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3261 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3262 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3264 See also section <ref id="macros" name="Macros">.
3267 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3269 Start a section of absolute code. The command is followed by a constant
3270 expression that gives the new PC counter location for which the code is
3271 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3274 By default, absolute/relocatable mode is global (valid even when switching
3275 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3276 it can be made segment local.
3278 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3279 code at a specific address is the job of the linker, not the assembler, so
3280 there is usually no reason to assemble code to a specific address.
3285 .org $7FF ; Emit code starting at $7FF
3289 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3291 Output a string to the console without producing an error. This command
3292 is similar to <tt/.ERROR/, however, it does not force an assembler error
3293 that prevents the creation of an object file.
3298 .out "This code was written by the codebuster(tm)"
3301 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3302 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3303 <tt><ref id=".WARNING" name=".WARNING"></tt>
3306 <sect1><tt>.P02</tt><label id=".P02"><p>
3308 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3309 instructions. This is the default if not overridden by the
3310 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3312 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3313 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3316 <sect1><tt>.P816</tt><label id=".P816"><p>
3318 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3319 6502 instruction sets.
3321 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3322 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3325 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3327 Set the page length for the listing. Must be followed by an integer
3328 constant. The value may be "unlimited", or in the range 32 to 127. The
3329 statement has no effect if no listing is generated. The default value is -1
3330 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3331 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3332 after assembly is complete, you cannot use multiple line lengths with one
3333 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3338 .pagelength 66 ; Use 66 lines per listing page
3340 .pagelength unlimited ; Unlimited page length
3344 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3346 Enable the 65C02 instructions set. This instruction set includes all
3347 6502 and 65SC02 instructions.
3349 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3350 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3353 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3355 Pop the last CPU setting from the stack, and activate it.
3357 This command will switch back to the CPU that was last pushed onto the CPU
3358 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3359 remove this entry from the stack.
3361 The assembler will print an error message if the CPU stack is empty when
3362 this command is issued.
3364 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3365 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3368 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3370 Pop the last pushed segment from the stack, and set it.
3372 This command will switch back to the segment that was last pushed onto the
3373 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3374 command, and remove this entry from the stack.
3376 The assembler will print an error message if the segment stack is empty
3377 when this command is issued.
3379 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3382 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3384 Start a nested lexical level with the given name and adds a symbol with this
3385 name to the enclosing scope. All new symbols from now on are in the local
3386 lexical level and are accessible from outside only via <ref id="scopesyntax"
3387 name="explicit scope specification">. Symbols defined outside this local
3388 level may be accessed as long as their names are not used for new symbols
3389 inside the level. Symbols names in other lexical levels do not clash, so you
3390 may use the same names for identifiers. The lexical level ends when the
3391 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3392 may be nested up to a depth of 16 (this is an artificial limit to protect
3393 against errors in the source).
3395 Note: Macro names are always in the global level and in a separate name
3396 space. There is no special reason for this, it's just that I've never
3397 had any need for local macro definitions.
3402 .proc Clear ; Define Clear subroutine, start new level
3404 L1: sta Mem,y ; L1 is local and does not cause a
3405 ; duplicate symbol error if used in other
3408 bne L1 ; Reference local symbol
3410 .endproc ; Leave lexical level
3413 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3417 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3419 Enable the 65SC02 instructions set. This instruction set includes all
3422 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3423 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3426 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3428 Push the currently active CPU onto a stack. The stack has a size of 8
3431 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3432 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3433 later, without knowledge of the current CPU setting.
3435 The assembler will print an error message if the CPU stack is already full,
3436 when this command is issued.
3438 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3439 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3442 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3444 Push the currently active segment onto a stack. The entries on the stack
3445 include the name of the segment and the segment type. The stack has a size
3448 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3449 to switch to another segment and to restore the old segment later, without
3450 even knowing the name and type of the current segment.
3452 The assembler will print an error message if the segment stack is already
3453 full, when this command is issued.
3455 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3458 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3460 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3461 name=".ORG"></tt> command.
3464 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3466 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3467 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3468 a constant expression that tells how many times the commands in the body
3469 should get repeated. Optionally, a comma and an identifier may be specified.
3470 If this identifier is found in the body of the repeat statement, it is
3471 replaced by the current repeat count (starting with zero for the first time
3472 the body is repeated).
3474 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3475 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3476 level will be used, not the one from the outer level.
3480 The following macro will emit a string that is "encrypted" in that all
3481 characters of the string are XORed by the value $55.
3485 .repeat .strlen(Arg), I
3486 .byte .strat(Arg, I) ^ $55
3491 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3494 <sect1><tt>.RES</tt><label id=".RES"><p>
3496 Reserve storage. The command is followed by one or two constant
3497 expressions. The first one is mandatory and defines, how many bytes of
3498 storage should be defined. The second, optional expression must by a
3499 constant byte value that will be used as value of the data. If there
3500 is no fill value given, the linker will use the value defined in the
3501 linker configuration file (default: zero).
3506 ; Reserve 12 bytes of memory with value $AA
3511 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3513 Switch to the RODATA segment. The name of the RODATA segment is always
3514 "RODATA", so this is a shortcut for
3520 The RODATA segment is a segment that is used by the compiler for
3521 readonly data like string constants.
3523 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3526 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3528 Start a nested lexical level with the given name. All new symbols from now
3529 on are in the local lexical level and are accessible from outside only via
3530 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3531 outside this local level may be accessed as long as their names are not used
3532 for new symbols inside the level. Symbols names in other lexical levels do
3533 not clash, so you may use the same names for identifiers. The lexical level
3534 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3535 read. Lexical levels may be nested up to a depth of 16 (this is an
3536 artificial limit to protect against errors in the source).
3538 Note: Macro names are always in the global level and in a separate name
3539 space. There is no special reason for this, it's just that I've never
3540 had any need for local macro definitions.
3545 .scope Error ; Start new scope named Error
3547 File = 1 ; File error
3548 Parse = 2 ; Parse error
3549 .endscope ; Close lexical level
3552 lda #Error::File ; Use symbol from scope Error
3555 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3559 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3561 Switch to another segment. Code and data is always emitted into a
3562 segment, that is, a named section of data. The default segment is
3563 "CODE". There may be up to 254 different segments per object file
3564 (and up to 65534 per executable). There are shortcut commands for
3565 the most common segments ("CODE", "DATA" and "BSS").
3567 The command is followed by a string containing the segment name (there are
3568 some constraints for the name - as a rule of thumb use only those segment
3569 names that would also be valid identifiers). There may also be an optional
3570 address size separated by a colon. See the section covering <tt/<ref
3571 id="address-sizes" name="address sizes">/ for more information.
3573 The default address size for a segment depends on the memory model specified
3574 on the command line. The default is "absolute", which means that you don't
3575 have to use an address size modifier in most cases.
3577 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3578 That is, the segment will reside somewhere in core memory outside the zero
3579 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3580 page and direct (short) addressing is possible for data in this segment.
3582 Beware: Only labels in a segment with the zeropage attribute are marked
3583 as reachable by short addressing. The `*' (PC counter) operator will
3584 work as in other segments and will create absolute variable values.
3586 Please note that a segment cannot have two different address sizes. A
3587 segment specified as zeropage cannot be declared as being absolute later.
3592 .segment "ROM2" ; Switch to ROM2 segment
3593 .segment "ZP2": zeropage ; New direct segment
3594 .segment "ZP2" ; Ok, will use last attribute
3595 .segment "ZP2": absolute ; Error, redecl mismatch
3598 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3599 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3600 id=".RODATA" name=".RODATA"></tt>
3603 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3605 Switch the CPU instruction set. The command is followed by a string that
3606 specifies the CPU. Possible values are those that can also be supplied to
3607 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3608 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3609 note that support for the sunplus CPU is not available in the freeware
3610 version, because the instruction set of the sunplus CPU is "proprietary
3613 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3614 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3615 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3616 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3617 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3618 <tt><ref id=".P02" name=".P02"></tt>,
3619 <tt><ref id=".P816" name=".P816"></tt>,
3620 <tt><ref id=".PC02" name=".PC02"></tt>,
3621 <tt><ref id=".PSC02" name=".PSC02"></tt>
3624 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3626 Switch on or off smart mode. The command must be followed by a '+' or '-'
3627 character to switch the option on or off respectively. The default is off
3628 (that is, the assembler doesn't try to be smart), but this default may be
3629 changed by the -s switch on the command line.
3631 In smart mode the assembler will do the following:
3634 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3635 and update the operand sizes accordingly. If the operand of such an
3636 instruction cannot be evaluated by the assembler (for example, because
3637 the operand is an imported symbol), a warning is issued. Beware: Since
3638 the assembler cannot trace the execution flow this may lead to false
3639 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3640 instructions to tell the assembler about the current settings.
3641 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3642 used within a procedure declared as <tt/far/, or if the procedure has
3643 no explicit address specification, but it is <tt/far/ because of the
3651 .smart - ; Stop being smart
3654 See: <tt><ref id=".A16" name=".A16"></tt>,
3655 <tt><ref id=".A8" name=".A8"></tt>,
3656 <tt><ref id=".I16" name=".I16"></tt>,
3657 <tt><ref id=".I8" name=".I8"></tt>
3660 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3662 Starts a struct definition. Structs are covered in a separate section named
3663 <ref id="structs" name=""Structs and unions"">.
3665 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3668 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3670 Enable the SunPlus instructions set. This command will not work in the
3671 freeware version of the assembler, because the instruction set is
3672 "proprietary and confidential".
3674 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3675 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3676 <tt><ref id=".P816" name=".P816"></tt>
3679 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3681 Allocate space for a struct or union.
3692 .tag Point ; Allocate 4 bytes
3696 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3698 Delete a define style macro definition. The command is followed by an
3699 identifier which specifies the name of the macro to delete. Macro
3700 replacement is switched of when reading the token following the command
3701 (otherwise the macro name would be replaced by its replacement list).
3703 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3704 section <ref id="macros" name="Macros">.
3707 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3709 Force an assembly warning. The assembler will output a warning message
3710 preceded by "User warning". This warning will always be output, even if
3711 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3712 command line option.
3714 This command may be used to output possible problems when assembling
3723 .warning "Forward jump in jne, cannot optimize!"
3733 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>
3734 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3735 <tt><ref id=".OUT" name=".OUT"></tt>
3738 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3740 Define word sized data. Must be followed by a sequence of (word ranged,
3741 but not necessarily constant) expressions.
3746 .word $0D00, $AF13, _Clear
3750 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3752 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3753 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3757 .segment "ZEROPAGE", zeropage
3760 Because of the "zeropage" attribute, labels declared in this segment are
3761 addressed using direct addressing mode if possible. You <em/must/ instruct
3762 the linker to place this segment somewhere in the address range 0..$FF
3763 otherwise you will get errors.
3765 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3769 <sect>Macros<label id="macros"><p>
3772 <sect1>Introduction<p>
3774 Macros may be thought of as "parametrized super instructions". Macros are
3775 sequences of tokens that have a name. If that name is used in the source
3776 file, the macro is "expanded", that is, it is replaced by the tokens that
3777 were specified when the macro was defined.
3780 <sect1>Macros without parameters<p>
3782 In its simplest form, a macro does not have parameters. Here's an
3786 .macro asr ; Arithmetic shift right
3787 cmp #$80 ; Put bit 7 into carry
3788 ror ; Rotate right with carry
3792 The macro above consists of two real instructions, that are inserted into
3793 the code, whenever the macro is expanded. Macro expansion is simply done
3794 by using the name, like this:
3803 <sect1>Parametrized macros<p>
3805 When using macro parameters, macros can be even more useful:
3819 When calling the macro, you may give a parameter, and each occurrence of
3820 the name "addr" in the macro definition will be replaced by the given
3839 A macro may have more than one parameter, in this case, the parameters
3840 are separated by commas. You are free to give less parameters than the
3841 macro actually takes in the definition. You may also leave intermediate
3842 parameters empty. Empty parameters are replaced by empty space (that is,
3843 they are removed when the macro is expanded). If you have a look at our
3844 macro definition above, you will see, that replacing the "addr" parameter
3845 by nothing will lead to wrong code in most lines. To help you, writing
3846 macros with a variable parameter list, there are some control commands:
3848 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3849 returns true, if there are any tokens on the remainder of the line. Since
3850 empty parameters are replaced by nothing, this may be used to test if a given
3851 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3854 Look at this example:
3857 .macro ldaxy a, x, y
3870 This macro may be called as follows:
3873 ldaxy 1, 2, 3 ; Load all three registers
3875 ldaxy 1, , 3 ; Load only a and y
3877 ldaxy , , 3 ; Load y only
3880 There's another helper command for determining, which macro parameters are
3881 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3882 replaced by the parameter count given, <em/including/ intermediate empty macro
3886 ldaxy 1 ; .PARAMCOUNT = 1
3887 ldaxy 1,,3 ; .PARAMCOUNT = 3
3888 ldaxy 1,2 ; .PARAMCOUNT = 2
3889 ldaxy 1, ; .PARAMCOUNT = 2
3890 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3893 Macro parameters may optionally be enclosed into curly braces. This allows the
3894 inclusion of tokens that would otherwise terminate the parameter (the comma in
3895 case of a macro parameter).
3898 .macro foo arg1, arg2
3902 foo ($00,x) ; Two parameters passed
3903 foo {($00,x)} ; One parameter passed
3906 In the first case, the macro is called with two parameters: '<tt/($00/'
3907 and 'x)'. The comma is not passed to the macro, since it is part of the
3908 calling sequence, not the parameters.
3910 In the second case, '($00,x)' is passed to the macro, this time
3911 including the comma.
3914 <sect1>Detecting parameter types<p>
3916 Sometimes it is nice to write a macro that acts differently depending on the
3917 type of the argument supplied. An example would be a macro that loads a 16 bit
3918 value from either an immediate operand, or from memory. The <tt/<ref
3919 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3920 functions will allow you to do exactly this:
3924 .if (.match (.left (1, {arg}), #))
3926 lda #<(.right (.tcount ({arg})-1, {arg}))
3927 ldx #>(.right (.tcount ({arg})-1, {arg}))
3929 ; assume absolute or zero page
3936 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3937 check if its argument begins with a hash mark. If so, two immediate loads are
3938 emitted, Otherwise a load from an absolute zero page memory location is
3939 assumed. Please note how the curly braces are used to enclose parameters to
3940 pseudo functions handling token lists. This is necessary, because the token
3941 lists may include commas or parens, which would be treated by the assembler
3944 The macro can be used as
3949 ldax #$1234 ; X=$12, A=$34
3951 ldax foo ; X=$56, A=$78
3955 <sect1>Recursive macros<p>
3957 Macros may be used recursively:
3960 .macro push r1, r2, r3
3969 There's also a special macro to help writing recursive macros: <tt><ref
3970 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3974 .macro push r1, r2, r3, r4, r5, r6, r7
3976 ; First parameter is empty
3982 push r2, r3, r4, r5, r6, r7
3986 When expanding this macro, the expansion will push all given parameters
3987 until an empty one is encountered. The macro may be called like this:
3990 push $20, $21, $32 ; Push 3 ZP locations
3991 push $21 ; Push one ZP location
3995 <sect1>Local symbols inside macros<p>
3997 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3998 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3999 Have a look at the inc16 macro above. Here is it again:
4013 If you have a closer look at the code, you will notice, that it could be
4014 written more efficiently, like this:
4025 But imagine what happens, if you use this macro twice? Since the label
4026 "Skip" has the same name both times, you get a "duplicate symbol" error.
4027 Without a way to circumvent this problem, macros are not as useful, as
4028 they could be. One solution is, to start a new lexical block inside the
4042 Now the label is local to the block and not visible outside. However,
4043 sometimes you want a label inside the macro to be visible outside. To make
4044 that possible, there's a new command that's only usable inside a macro
4045 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
4046 or more symbols as local to the macro expansion. The names of local variables
4047 are replaced by a unique name in each separate macro expansion. So we could
4048 also solve the problem above by using <tt/.LOCAL/:
4052 .local Skip ; Make Skip a local symbol
4059 Skip: ; Not visible outside
4064 <sect1>C style macros<p>
4066 Starting with version 2.5 of the assembler, there is a second macro type
4067 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4068 similar to the classic macro type described above, but behaviour is sometimes
4073 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4074 span more than a line. You may use line continuation (see <tt><ref
4075 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4076 more than one line for increased readability, but the macro itself
4077 may not contain an end-of-line token.
4079 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4080 the name space with classic macros, but they are detected and replaced
4081 at the scanner level. While classic macros may be used in every place,
4082 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4083 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4084 they are more versatile in some situations.
4086 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4087 parameters. While classic macros may have empty parameters, this is
4088 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4089 For this macro type, the number of actual parameters must match
4090 exactly the number of formal parameters.
4092 To make this possible, formal parameters are enclosed in braces when
4093 defining the macro. If there are no parameters, the empty braces may
4096 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4097 contain end-of-line tokens, there are things that cannot be done. They
4098 may not contain several processor instructions for example. So, while
4099 some things may be done with both macro types, each type has special
4100 usages. The types complement each other.
4104 Let's look at a few examples to make the advantages and disadvantages
4107 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4108 following <tt/.DEFINE/:
4113 foo EQU $1234 ; This is accepted now
4116 You may use the directive to define string constants used elsewhere:
4119 ; Define the version number
4120 .define VERSION "12.3a"
4126 Macros with parameters may also be useful:
4129 .define DEBUG(message) .out message
4131 DEBUG "Assembling include file #3"
4134 Note that, while formal parameters have to be placed in braces, this is
4135 not true for the actual parameters. Beware: Since the assembler cannot
4136 detect the end of one parameter, only the first token is used. If you
4137 don't like that, use classic macros instead:
4145 (This is an example where a problem can be solved with both macro types).
4148 <sect1>Characters in macros<p>
4150 When using the <ref id="option-t" name="-t"> option, characters are translated
4151 into the target character set of the specific machine. However, this happens
4152 as late as possible. This means that strings are translated if they are part
4153 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4154 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4155 used as part of an expression.
4157 This behaviour is very intuitive outside of macros but may be confusing when
4158 doing more complex macros. If you compare characters against numeric values,
4159 be sure to take the translation into account.
4162 <sect1>Deleting macros<p>
4164 Macros can be deleted. This will not work if the macro that should be deleted
4165 is currently expanded as in the following non working example:
4169 .delmacro notworking
4172 notworking ; Will not work
4175 The commands to delete classic and define style macros differ. Classic macros
4176 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4177 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4178 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4186 .byte value ; Emit one byte with value 1
4187 mac ; Emit another byte with value 2
4192 .byte value ; Error: Unknown identifier
4193 mac ; Error: Missing ":"
4196 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4197 the name of such a macro is replaced by its replacement list on a very low
4198 level. To get the actual name, macro replacement has to be switched off when
4199 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4200 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4201 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4202 different commands increases flexibility.
4205 <sect>Macro packages<label id="macropackages"><p>
4207 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4208 macro packages may be included with just one command. Available macro packages
4212 <sect1><tt>.MACPACK generic</tt><p>
4214 This macro package defines macros that are useful in almost any program.
4215 Currently defined macros are:
4250 <sect1><tt>.MACPACK longbranch</tt><p>
4252 This macro package defines long conditional jumps. They are named like the
4253 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4254 definition for the "<tt/jeq/" macro, the other macros are built using the same
4259 .if .def(Target) .and ((*+2)-(Target) <= 127)
4268 All macros expand to a short branch, if the label is already defined (back
4269 jump) and is reachable with a short jump. Otherwise the macro expands to a
4270 conditional branch with the branch condition inverted, followed by an absolute
4271 jump to the actual branch target.
4273 The package defines the following macros:
4276 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4281 <sect1><tt>.MACPACK atari</tt><p>
4283 The atari macro package will define a macro named <tt/scrcode/. It takes a
4284 string as argument and places this string into memory translated into screen
4288 <sect1><tt>.MACPACK cbm</tt><p>
4290 The cbm macro package will define a macro named <tt/scrcode/. It takes a
4291 string as argument and places this string into memory translated into screen
4295 <sect1><tt>.MACPACK cpu</tt><p>
4297 This macro package does not define any macros but constants used to examine
4298 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4299 each supported CPU a constant similar to
4311 is defined. These constants may be used to determine the exact type of the
4312 currently enabled CPU. In addition to that, for each CPU instruction set,
4313 another constant is defined:
4325 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4326 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4327 currently enabled CPU supports a specific instruction set. For example the
4328 65C02 supports all instructions of the 65SC02 CPU, so it has the
4329 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4333 .if (.cpu .bitand CPU_ISET_65SC02)
4341 it is possible to determine if the
4347 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4348 CPUs (the latter two are upwards compatible to the 65SC02).
4352 <sect>Predefined constants<label id="predefined-constants"><p>
4354 For better orthogonality, the assembler defines similar symbols as the
4355 compiler, depending on the target system selected:
4358 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
4359 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4360 <item><tt/__ATARI__/ - Target system is <tt/atari/
4361 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4362 <item><tt/__BBC__/ - Target system is <tt/bbc/
4363 <item><tt/__C128__/ - Target system is <tt/c128/
4364 <item><tt/__C16__/ - Target system is <tt/c16/
4365 <item><tt/__C64__/ - Target system is <tt/c64/
4366 <item><tt/__CBM__/ - Target is a Commodore system
4367 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4368 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4369 <item><tt/__GEOS__/ - Target system is <tt/geos/
4370 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4371 <item><tt/__NES__/ - Target system is <tt/nes/
4372 <item><tt/__PET__/ - Target system is <tt/pet/
4373 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4374 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4375 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4379 <sect>Structs and unions<label id="structs"><p>
4381 <sect1>Structs and unions Overview<p>
4383 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4384 are to some degree comparable to their C counterparts. Both have a list of
4385 members. Each member allocates storage and may optionally have a name, which,
4386 in case of a struct, is the offset from the beginning and, in case of a union,
4390 <sect1>Declaration<p>
4392 Here is an example for a very simple struct with two members and a total size
4402 A union shares the total space between all its members, its size is the same
4403 as that of the largest member.
4405 A struct or union must not necessarily have a name. If it is anonymous, no
4406 local scope is opened, the identifiers used to name the members are placed
4407 into the current scope instead.
4409 A struct may contain unnamed members and definitions of local structs. The
4410 storage allocators may contain a multiplier, as in the example below:
4415 .word 2 ; Allocate two words
4422 <sect1>The <tt/.TAG/ keyword<p>
4424 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4425 for an already defined struct or unions within another struct:
4439 Space for a struct or union may be allocated using the <ref id=".TAG"
4440 name=".TAG"> directive.
4446 Currently, members are just offsets from the start of the struct or union. To
4447 access a field of a struct, the member offset has to be added to the address
4448 of the struct itself:
4451 lda C+Circle::Radius ; Load circle radius into A
4454 This may change in a future version of the assembler.
4457 <sect1>Limitations<p>
4459 Structs and unions are currently implemented as nested symbol tables (in fact,
4460 they were a by-product of the improved scoping rules). Currently, the
4461 assembler has no idea of types. This means that the <ref id=".TAG"
4462 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4463 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4464 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4465 this structure accessible by using the '::' operator.
4469 <sect>Module constructors/destructors<label id="condes"><p>
4471 <em>Note:</em> This section applies mostly to C programs, so the explanation
4472 below uses examples from the C libraries. However, the feature may also be
4473 useful for assembler programs.
4476 <sect1>Module constructors/destructors Overview<p>
4478 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4479 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4480 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
4481 special way. The linker is able to generate tables with all functions of a
4482 specific type. Such a table will <em>only</em> include symbols from object
4483 files that are linked into a specific executable. This may be used to add
4484 initialization and cleanup code for library modules, or a table of interrupt
4487 The C heap functions are an example where module initialization code is used.
4488 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4489 variables that contain the start and the end of the heap, pointers to the free
4490 list and so on. Since the end of the heap depends on the size and start of the
4491 stack, it must be initialized at runtime. However, initializing these
4492 variables for programs that do not use the heap are a waste of time and
4495 So the central module defines a function that contains initialization code and
4496 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4497 this module is added to an executable by the linker, the initialization
4498 function will be placed into the table of constructors by the linker. The C
4499 startup code will call all constructors before <tt/main/ and all destructors
4500 after <tt/main/, so without any further work, the heap initialization code is
4501 called once the module is linked in.
4503 While it would be possible to add explicit calls to initialization functions
4504 in the startup code, the new approach has several advantages:
4508 If a module is not included, the initialization code is not linked in and not
4509 called. So you don't pay for things you don't need.
4512 Adding another library that needs initialization does not mean that the
4513 startup code has to be changed. Before we had module constructors and
4514 destructors, the startup code for all systems had to be adjusted to call the
4515 new initialization code.
4518 The feature saves memory: Each additional initialization function needs just
4519 two bytes in the table (a pointer to the function).
4524 <sect1>Calling order<p>
4526 The symbols are sorted in increasing priority order by the linker when using
4527 one of the builtin linker configurations, so the functions with lower
4528 priorities come first and are followed by those with higher priorities. The C
4529 library runtime subroutine that walks over the function tables calls the
4530 functions starting from the top of the table - which means that functions with
4531 a high priority are called first.
4533 So when using the C runtime, functions are called with high priority functions
4534 first, followed by low priority functions.
4539 When using these special symbols, please take care of the following:
4544 The linker will only generate function tables, it will not generate code to
4545 call these functions. If you're using the feature in some other than the
4546 existing C environments, you have to write code to call all functions in a
4547 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4548 in the C runtime for an example on how to do this.
4551 The linker will only add addresses of functions that are in modules linked to
4552 the executable. This means that you have to be careful where to place the
4553 condes functions. If initialization or an irq handler is needed for a group of
4554 functions, be sure to place the function into a module that is linked in
4555 regardless of which function is called by the user.
4558 The linker will generate the tables only when requested to do so by the
4559 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4560 be requested separately.
4563 Constructors and destructors may have priorities. These priorities determine
4564 the order of the functions in the table. If your initialization or cleanup code
4565 does depend on other initialization or cleanup code, you have to choose the
4566 priority for the functions accordingly.
4569 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4570 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4571 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4572 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4573 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4574 (interruptor). The linker generates a separate table for each type on request.
4579 <sect>Porting sources from other assemblers<p>
4581 Sometimes it is necessary to port code written for older assemblers to ca65.
4582 In some cases, this can be done without any changes to the source code by
4583 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4584 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4587 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4588 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4589 done by the linker. Most other assemblers generate absolute code, placement is
4590 done within the assembler and there is no external linker.
4592 In general it is not a good idea to write new code using the emulation
4593 features of the assembler, but there may be situations where even this rule is
4598 You need to use some of the ca65 emulation features to simulate the behaviour
4599 of such simple assemblers.
4602 <item>Prepare your sourcecode like this:
4605 ; if you want TASS style labels without colons
4606 .feature labels_without_colons
4608 ; if you want TASS style character constants
4609 ; ("a" instead of the default 'a')
4610 .feature loose_char_term
4612 .word *+2 ; the cbm load address
4617 notice that the two emulation features are mostly useful for porting
4618 sources originally written in/for TASS, they are not needed for the
4619 actual "simple assembler operation" and are not recommended if you are
4620 writing new code from scratch.
4622 <item>Replace all program counter assignments (which are not possible in ca65
4623 by default, and the respective emulation feature works different from what
4624 you'd expect) by another way to skip to memory locations, for example the
4625 <tt><ref id=".RES" name=".RES"></tt> directive.
4629 .res $2000-* ; reserve memory up to $2000
4632 Please note that other than the original TASS, ca65 can never move the program
4633 counter backwards - think of it as if you are assembling to disk with TASS.
4635 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4636 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4637 of <tt/.goto/, everything involving loops must be replaced by
4638 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4640 <item>To assemble code to a different address than it is executed at, use the
4641 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4642 <tt/.offs/-constructs.
4649 .reloc ; back to normal
4652 <item>Then assemble like this:
4655 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4658 Note that you need to use the actual start address minus two, since two bytes
4659 are used for the cbm load address.
4664 <sect>Bugs/Feedback<p>
4666 If you have problems using the assembler, if you find any bugs, or if
4667 you're doing something interesting with the assembler, I would be glad to
4668 hear from you. Feel free to contact me by email
4669 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4675 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4676 Bassewitz. For usage of the binaries and/or sources the following
4677 conditions do apply:
4679 This software is provided 'as-is', without any expressed or implied
4680 warranty. In no event will the authors be held liable for any damages
4681 arising from the use of this software.
4683 Permission is granted to anyone to use this software for any purpose,
4684 including commercial applications, and to alter it and redistribute it
4685 freely, subject to the following restrictions:
4688 <item> The origin of this software must not be misrepresented; you must not
4689 claim that you wrote the original software. If you use this software
4690 in a product, an acknowledgment in the product documentation would be
4691 appreciated but is not required.
4692 <item> Altered source versions must be plainly marked as such, and must not
4693 be misrepresented as being the original software.
4694 <item> This notice may not be removed or altered from any source