1 <!doctype linuxdoc system> <!-- -*- text-mode -*- -->
4 <title>ca65 Users Guide
5 <author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">
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
96 -g Add debug info to object file
98 -i Ignore case of symbols
99 -l name Create a listing file if assembly was ok
100 -mm model Set the memory model
101 -o name Name the output file
103 -t sys Set the target system
104 -v Increase verbosity
107 --auto-import Mark unresolved symbols as import
108 --bin-include-dir dir Set a search path for binary includes
109 --cpu type Set cpu type
110 --create-dep name Create a make dependency file
111 --create-full-dep name Create a full make dependency file
113 --debug-info Add debug info to object file
114 --feature name Set an emulation feature
115 --help Help (this text)
116 --ignore-case Ignore case of symbols
117 --include-dir dir Set an include directory search path
118 --large-alignment Don't warn about large alignments
119 --listing name Create a listing file if assembly was ok
120 --list-bytes n Maximum number of bytes per listing line
121 --memory-model model Set the memory model
122 --pagelength n Set the page length for the listing
123 --relax-checks Relax some checks (see docs)
124 --smart Enable smart mode
125 --target sys Set the target system
126 --verbose Increase verbosity
127 --version Print the assembler version
128 ---------------------------------------------------------------------------
132 <sect1>Command line options in detail<p>
134 Here is a description of all the command line options:
138 <label id="option--bin-include-dir">
139 <tag><tt>--bin-include-dir dir</tt></tag>
141 Name a directory which is searched for binary include files. The option
142 may be used more than once to specify more than one directory to search. The
143 current directory is always searched first before considering any
144 additional directories. See also the section about <ref id="search-paths"
145 name="search paths">.
148 <label id="option--cpu">
149 <tag><tt>--cpu type</tt></tag>
151 Set the default for the CPU type. The option takes a parameter, which
154 6502, 65SC02, 65C02, 65816, sweet16, HuC6280
157 <label id="option-create-dep">
158 <tag><tt>--create-dep name</tt></tag>
160 Tells the assembler to generate a file containing the dependency list for
161 the assembled module in makefile syntax. The output is written to a file
162 with the given name. The output does not include files passed via debug
163 information to the assembler.
166 <label id="option-create-full-dep">
167 <tag><tt>--create-full-dep name</tt></tag>
169 Tells the assembler to generate a file containing the dependency list for
170 the assembled module in makefile syntax. The output is written to a file
171 with the given name. The output does include files passed via debug
172 information to the assembler.
175 <tag><tt>-d, --debug</tt></tag>
177 Enables debug mode, something that should not be needed for mere
181 <label id="option--feature">
182 <tag><tt>--feature name</tt></tag>
184 Enable an emulation feature. This is identical as using <tt/.FEATURE/
185 in the source with two exceptions: Feature names must be lower case, and
186 each feature must be specified by using an extra <tt/--feature/ option,
187 comma separated lists are not allowed.
189 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
190 command for a list of emulation features.
193 <label id="option-g">
194 <tag><tt>-g, --debug-info</tt></tag>
196 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
197 used, the assembler will add a section to the object file that contains
198 all symbols (including local ones) together with the symbol values and
199 source file positions. The linker will put these additional symbols into
200 the VICE label file, so even local symbols can be seen in the VICE
204 <label id="option-h">
205 <tag><tt>-h, --help</tt></tag>
207 Print the short option summary shown above.
210 <label id="option-i">
211 <tag><tt>-i, --ignore-case</tt></tag>
213 This option makes the assembler case insensitive on identifiers and labels.
214 This option will override the default, but may itself be overridden by the
215 <tt><ref id=".CASE" name=".CASE"></tt> control command.
218 <label id="option-l">
219 <tag><tt>-l name, --listing name</tt></tag>
221 Generate an assembler listing with the given name. A listing file will
222 never be generated in case of assembly errors.
225 <label id="option--large-alignment">
226 <tag><tt>--large-alignment</tt></tag>
228 Disable warnings about a large combined alignment. See the discussion of the
229 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
232 <label id="option--list-bytes">
233 <tag><tt>--list-bytes n</tt></tag>
235 Set the maximum number of bytes printed in the listing for one line of
236 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
237 for more information. The value zero can be used to encode an unlimited
238 number of printed bytes.
241 <label id="option-mm">
242 <tag><tt>-mm model, --memory-model model</tt></tag>
244 Define the default memory model. Possible model specifiers are near, far and
248 <label id="option-o">
249 <tag><tt>-o name</tt></tag>
251 The default output name is the name of the input file with the extension
252 replaced by ".o". If you don't like that, you may give another name with
253 the -o option. The output file will be placed in the same directory as
254 the source file, or, if -o is given, the full path in this name is used.
257 <label id="option--pagelength">
258 <tag><tt>--pagelength n</tt></tag>
260 sets the length of a listing page in lines. See the <tt><ref
261 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
264 <label id="option--relax-checks">
265 <tag><tt>--relax-checks</tt></tag>
267 Relax some checks done by the assembler. This will allow code that is an
268 error in most cases and flagged as such by the assembler, but can be valid
269 in special situations.
273 <item>Short branches between two different segments.
274 <item>Byte sized address loads where the address is not a zeropage address.
278 <label id="option-s">
279 <tag><tt>-s, --smart-mode</tt></tag>
281 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
282 pseudo instruction) the assembler will track usage of the <tt/REP/ and
283 <tt/SEP/ instructions in 65816 mode and update the operand sizes
284 accordingly. If the operand of such an instruction cannot be evaluated by
285 the assembler (for example, because the operand is an imported symbol), a
288 Beware: Since the assembler cannot trace the execution flow this may
289 lead to false results in some cases. If in doubt, use the .ixx and .axx
290 instructions to tell the assembler about the current settings. Smart
291 mode is off by default.
294 <label id="option-t">
295 <tag><tt>-t sys, --target sys</tt></tag>
297 Set the target system. This will enable translation of character strings and
298 character constants into the character set of the target platform. The
299 default for the target system is "none", which means that no translation
300 will take place. The assembler supports the same target systems as the
301 compiler, see there for a list.
303 Depending on the target, the default CPU type is also set. This can be
304 overriden by using the <tt/<ref id="option--cpu" name="--cpu">/ option.
307 <label id="option-v">
308 <tag><tt>-v, --verbose</tt></tag>
310 Increase the assembler verbosity. Usually only needed for debugging
311 purposes. You may use this option more than one time for even more
315 <label id="option-D">
316 <tag><tt>-D</tt></tag>
318 This option allows you to define symbols on the command line. Without a
319 value, the symbol is defined with the value zero. When giving a value,
320 you may use the '$' prefix for hexadecimal symbols. Please note
321 that for some operating systems, '$' has a special meaning, so
322 you may have to quote the expression.
325 <label id="option-I">
326 <tag><tt>-I dir, --include-dir dir</tt></tag>
328 Name a directory which is searched for include files. The option may be
329 used more than once to specify more than one directory to search. The
330 current directory is always searched first before considering any
331 additional directories. See also the section about <ref id="search-paths"
332 name="search paths">.
335 <label id="option-U">
336 <tag><tt>-U, --auto-import</tt></tag>
338 Mark symbols that are not defined in the sources as imported symbols. This
339 should be used with care since it delays error messages about typos and such
340 until the linker is run. The compiler uses the equivalent of this switch
341 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
342 symbols for the runtime library. However, the compiler is supposed to
343 generate code that runs through the assembler without problems, something
344 which is not always true for assembler programmers.
347 <label id="option-V">
348 <tag><tt>-V, --version</tt></tag>
350 Print the version number of the assembler. If you send any suggestions
351 or bugfixes, please include the version number.
354 <label id="option-W">
355 <tag><tt>-Wn</tt></tag>
357 Set the warning level for the assembler. Using -W2 the assembler will
358 even warn about such things like unused imported symbols. The default
359 warning level is 1, and it would probably be silly to set it to
367 <sect>Search paths<label id="search-paths"><p>
369 Normal include files are searched in the following places:
372 <item>The current file's directory.
373 <item>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
375 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
376 <item>A subdirectory named <tt/asminc/ of the directory defined in the
377 environment variable <tt/CC65_HOME/, if it is defined.
378 <item>An optionally compiled-in directory.
381 Binary include files are searched in the following places:
384 <item>The current file's directory.
385 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
386 name="--bin-include-dir">/ option on the command line.
391 <sect>Input format<p>
393 <sect1>Assembler syntax<p>
395 The assembler accepts the standard 6502/65816 assembler syntax. One line may
396 contain a label (which is identified by a colon), and, in addition to the
397 label, an assembler mnemonic, a macro, or a control command (see section <ref
398 id="control-commands" name="Control Commands"> for supported control
399 commands). Alternatively, the line may contain a symbol definition using
400 the '=' token. Everything after a semicolon is handled as a comment (that is,
403 Here are some examples for valid input lines:
406 Label: ; A label and a comment
407 lda #$20 ; A 6502 instruction plus comment
408 L1: ldx #$20 ; Same with label
409 L2: .byte "Hello world" ; Label plus control command
410 mymac $20 ; Macro expansion
411 MySym = 3*L1 ; Symbol definition
412 MaSym = Label ; Another symbol
415 The assembler accepts
418 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
419 <tt><ref id=".P02" name=".P02"></tt> command was given).
420 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
421 <ref id="6502X-mode" name="6502X mode">.
422 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
423 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
424 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
425 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
426 <item>all valid 65618 mnemonics when in 65816 mode (after the
427 <tt><ref id=".P816" name=".P816"></tt> command was given).
433 In 65816 mode several aliases are accepted in addition to the official
437 BGE is an alias for BCS
438 BLT is an alias for BCC
439 CPA is an alias for CMP
440 DEA is an alias for DEC A
441 INA is an alias for INC A
442 SWA is an alias for XBA
443 TAD is an alias for TCD
444 TAS is an alias for TCS
445 TDA is an alias for TDC
446 TSA is an alias for TSC
451 <sect1>6502X mode<label id="6502X-mode"><p>
453 6502X mode is an extension to the normal 6502 mode. In this mode, several
454 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
455 these instructions are illegal, there are no official mnemonics for them. The
456 unofficial ones are taken from <url
457 url="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
458 ones marked as "stable" are supported. The following table uses information
459 from the mentioned web page, for more information, see there.
462 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
463 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
464 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
465 <item><tt>AXS: X:=A and X-#{imm};</tt>
466 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
467 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
468 <item><tt>LAS: A,X,S:={adr} and S;</tt>
469 <item><tt>LAX: A,X:={adr};</tt>
470 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
471 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
472 <item><tt>SAX: {adr}:=A and X;</tt>
473 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
474 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
479 <sect1>sweet16 mode<label id="sweet16-mode"><p>
481 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
482 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
483 generate code for this pseudo CPU when switched into sweet16 mode. The
484 following is special in sweet16 mode:
488 <item>The '@' character denotes indirect addressing and is no longer available
489 for cheap local labels. If you need cheap local labels, you will have to
490 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
491 name=".LOCALCHAR">/ command.
493 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
494 these identifiers are reserved words.
498 Please note that the assembler does neither supply the interpreter needed for
499 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
500 nor does it call the interpreter. All this must be done by your program. Apple
501 ][ programmers do probably know how to use sweet16 mode.
503 For more information about SWEET 16, see
504 <url url="http://www.6502.org/source/interpreters/sweet16.htm">.
507 <sect1>Number format<p>
509 For literal values, the assembler accepts the widely used number formats: A
510 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
511 denotes a binary value, and a bare number is interpreted as a decimal. There
512 are currently no octal values and no floats.
515 <sect1>Conditional assembly<p>
517 Please note that when using the conditional directives (<tt/.IF/ and friends),
518 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
519 that are not assembled. The reason for this behaviour is that the assembler
520 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
521 conversion of the input stream into tokens still takes place. As a consequence
522 conditional assembly directives may <bf/not/ be used to prevent normal text
523 (used as a comment or similar) from being assembled. <p>
529 <sect1>Expression evaluation<p>
531 All expressions are evaluated with (at least) 32 bit precision. An
532 expression may contain constant values and any combination of internal and
533 external symbols. Expressions that cannot be evaluated at assembly time
534 are stored inside the object file for evaluation by the linker.
535 Expressions referencing imported symbols must always be evaluated by the
539 <sect1>Size of an expression result<p>
541 Sometimes, the assembler must know about the size of the value that is the
542 result of an expression. This is usually the case, if a decision has to be
543 made, to generate a zero page or an absolute memory references. In this
544 case, the assembler has to make some assumptions about the result of an
548 <item> If the result of an expression is constant, the actual value is
549 checked to see if it's a byte sized expression or not.
550 <item> If the expression is explicitly casted to a byte sized expression by
551 one of the '>', '<' or '^' operators, it is a byte expression.
552 <item> If this is not the case, and the expression contains a symbol,
553 explicitly declared as zero page symbol (by one of the .importzp or
554 .exportzp instructions), then the whole expression is assumed to be
556 <item> If the expression contains symbols that are not defined, and these
557 symbols are local symbols, the enclosing scopes are searched for a
558 symbol with the same name. If one exists and this symbol is defined,
559 its attributes are used to determine the result size.
560 <item> In all other cases the expression is assumed to be word sized.
563 Note: If the assembler is not able to evaluate the expression at assembly
564 time, the linker will evaluate it and check for range errors as soon as
568 <sect1>Boolean expressions<p>
570 In the context of a boolean expression, any non zero value is evaluated as
571 true, any other value to false. The result of a boolean expression is 1 if
572 it's true, and zero if it's false. There are boolean operators with extreme
573 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
574 operators are shortcut operators. That is, if the result of the expression is
575 already known, after evaluating the left hand side, the right hand side is
579 <sect1>Constant expressions<p>
581 Sometimes an expression must evaluate to a constant without looking at any
582 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
583 that decides if parts of the code are assembled or not. An expression used in
584 the <tt/.IF/ command cannot reference a symbol defined later, because the
585 decision about the <tt/.IF/ must be made at the point when it is read. If the
586 expression used in such a context contains only constant numerical values,
587 there is no problem. When unresolvable symbols are involved it may get harder
588 for the assembler to determine if the expression is actually constant, and it
589 is even possible to create expressions that aren't recognized as constant.
590 Simplifying the expressions will often help.
592 In cases where the result of the expression is not needed immediately, the
593 assembler will delay evaluation until all input is read, at which point all
594 symbols are known. So using arbitrary complex constant expressions is no
595 problem in most cases.
599 <sect1>Available operators<label id="operators"><p>
603 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
604 | Built-in string functions| 0@
606 | Built-in pseudo-variables| 1@
607 | Built-in pseudo-functions| 1@
608 +| Unary positive| 1@
609 -| Unary negative| 1@
611 .BITNOT| Unary bitwise not| 1@
613 .LOBYTE| Unary low-byte operator| 1@
615 .HIBYTE| Unary high-byte operator| 1@
617 .BANKBYTE| Unary bank-byte operator| 1@
619 *| Multiplication| 2@
621 .MOD| Modulo operator| 2@
623 .BITAND| Bitwise and| 2@
625 .BITXOR| Binary bitwise xor| 2@
627 .SHL| Shift-left operator| 2@
629 .SHR| Shift-right operator| 2@
631 +| Binary addition| 3@
632 -| Binary subtraction| 3@
634 .BITOR| Bitwise or| 3@
636 = | Compare operator (equal)| 4@
637 <>| Compare operator (not equal)| 4@
638 <| Compare operator (less)| 4@
639 >| Compare operator (greater)| 4@
640 <=| Compare operator (less or equal)| 4@
641 >=| Compare operator (greater or equal)| 4@
644 .AND| Boolean and| 5@
645 .XOR| Boolean xor| 5@
647 ||<newline>
651 .NOT| Boolean not| 7@<hline>
653 <caption>Available operators, sorted by precedence
656 To force a specific order of evaluation, parentheses may be used, as usual.
660 <sect>Symbols and labels<p>
662 A symbol or label is an identifier that starts with a letter and is followed
663 by letters and digits. Depending on some features enabled (see
664 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
665 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
666 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
667 other characters may be present. Use of identifiers consisting of a single
668 character will not work in all cases, because some of these identifiers are
669 reserved keywords (for example "A" is not a valid identifier for a label,
670 because it is the keyword for the accumulator).
672 The assembler allows you to use symbols instead of naked values to make
673 the source more readable. There are a lot of different ways to define and
674 use symbols and labels, giving a lot of flexibility.
676 <sect1>Numeric constants<p>
678 Numeric constants are defined using the equal sign or the label assignment
679 operator. After doing
685 may use the symbol "two" in every place where a number is expected, and it is
686 evaluated to the value 2 in this context. The label assignment operator is
687 almost identical, but causes the symbol to be marked as a label, so it may be
688 handled differently in a debugger:
694 The right side can of course be an expression:
701 <label id="variables">
702 <sect1>Numeric variables<p>
704 Within macros and other control structures (<tt><ref id=".REPEAT"
705 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
706 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
707 symbol that may get assigned a different value later:
711 lda #four ; Loads 4 into A
713 lda #four ; Loads 3 into A
716 Since the value of the symbol can change later, it must be possible to
717 evaluate it when used (no delayed evaluation as with normal symbols). So the
718 expression used as the value must be constant.
720 Following is an example for a macro that generates a different label each time
721 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
722 and a numeric variable named <tt>lcount</tt>.
725 .lcount .set 0 ; Initialize the counter
728 .ident (.sprintf ("L%04X", lcount)):
729 lcount .set lcount + 1
734 <sect1>Standard labels<p>
736 A label is defined by writing the name of the label at the start of the line
737 (before any instruction mnemonic, macro or pseudo directive), followed by a
738 colon. This will declare a symbol with the given name and the value of the
739 current program counter.
742 <sect1>Local labels and symbols<p>
744 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
745 create regions of code where the names of labels and symbols are local to this
746 region. They are not known outside of this region and cannot be accessed from
747 there. Such regions may be nested like PROCEDUREs in Pascal.
749 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
750 directive for more information.
753 <sect1>Cheap local labels<p>
755 Cheap local labels are defined like standard labels, but the name of the
756 label must begin with a special symbol (usually '@', but this can be
757 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
760 Cheap local labels are visible only between two non cheap labels. As soon as a
761 standard symbol is encountered (this may also be a local symbol if inside a
762 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
763 cheap local symbol goes out of scope.
765 You may use cheap local labels as an easy way to reuse common label
766 names like "Loop". Here is an example:
769 Clear: lda #$00 ; Global label
771 @Loop: sta Mem,y ; Local label
775 Sub: ... ; New global label
776 bne @Loop ; ERROR: Unknown identifier!
779 <sect1>Unnamed labels<p>
781 If you really want to write messy code, there are also unnamed labels. These
782 labels do not have a name (you guessed that already, didn't you?). A colon is
783 used to mark the absence of the name.
785 Unnamed labels may be accessed by using the colon plus several minus or plus
786 characters as a label designator. Using the '-' characters will create a back
787 reference (use the n'th label backwards), using '+' will create a forward
788 reference (use the n'th label in forward direction). An example will help to
811 As you can see from the example, unnamed labels will make even short
812 sections of code hard to understand, because you have to count labels
813 to find branch targets (this is the reason why I for my part do
814 prefer the "cheap" local labels). Nevertheless, unnamed labels are
815 convenient in some situations, so it's your decision.
817 <bf/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
818 unnamed ones, so scopes don't have an effect on unnamed labels.
822 <sect1>Using macros to define labels and constants<p>
824 While there are drawbacks with this approach, it may be handy in a few rare
825 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
826 to define symbols or constants that may be used elsewhere. One of the
827 advantages is that you can use it to define string constants (this is not
828 possible with the other symbol types).
830 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
831 so the names do not adhere to scoping, diagnostics may be misleading, there
832 are no symbols to look up in the map file, and there is no debug info.
833 Especially the first problem in the list can lead to very nasty programming
834 errors. Because of these problems, the general advice is, <bf/NOT/ do use
835 <tt/.DEFINE/ if you don't have to.
841 .DEFINE version "SOS V2.3"
843 four = two * two ; Ok
846 .PROC ; Start local scope
847 two = 3 ; Will give "2 = 3" - invalid!
852 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
854 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
855 id="option-g" name="-g"> is given on the command line), global, local and
856 cheap local labels are written to the object file and will be available in the
857 symbol file via the linker. Unnamed labels are not written to the object file,
858 because they don't have a name which would allow to access them.
862 <sect>Scopes<label id="scopes"><p>
864 ca65 implements several sorts of scopes for symbols.
866 <sect1>Global scope<p>
868 All (non cheap local) symbols that are declared outside of any nested scopes
872 <sect1>Cheap locals<p>
874 A special scope is the scope for cheap local symbols. It lasts from one non
875 local symbol to the next one, without any provisions made by the programmer.
876 All other scopes differ in usage but use the same concept internally.
879 <sect1>Generic nested scopes<p>
881 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
882 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
883 The scope can have a name, in which case it is accessible from the outside by
884 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
885 have a name, all symbols created within the scope are local to the scope, and
886 aren't accessible from the outside.
888 A nested scope can access symbols from the local or from enclosing scopes by
889 name without using explicit scope names. In some cases there may be
890 ambiguities, for example if there is a reference to a local symbol that is not
891 yet defined, but a symbol with the same name exists in outer scopes:
903 In the example above, the <tt/lda/ instruction will load the value 3 into the
904 accumulator, because <tt/foo/ is redefined in the scope. However:
916 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
917 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
918 absolute mode is used instead. In fact, the assembler will not use absolute
919 mode by default, but it will search through the enclosing scopes for a symbol
920 with the given name. If one is found, the address size of this symbol is used.
921 This may lead to errors:
933 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
934 instruction, it will search for an already defined symbol <tt/foo/. It will
935 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
936 zeropage symbol. So the assembler will use zeropage addressing mode. If
937 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
938 the address in the <tt/lda/ instruction already translated, but since the new
939 value needs absolute addressing mode, this fails, and an error message "Range
942 Of course the most simple solution for the problem is to move the definition
943 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
944 rare cases when this cannot be done. In these cases, you can use one of the
945 address size override operators:
957 This will cause the <tt/lda/ instruction to be translated using absolute
958 addressing mode, which means changing the symbol reference later does not
962 <sect1>Nested procedures<p>
964 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
965 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
966 name, and a it will introduce a symbol with this name in the enclosing scope.
975 is actually the same as
984 This is the reason why a procedure must have a name. If you want a scope
985 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
987 <bf/Note:/ As you can see from the example above, scopes and symbols live in
988 different namespaces. There can be a symbol named <tt/foo/ and a scope named
989 <tt/foo/ without any conflicts (but see the section titled <ref
990 id="scopesearch" name=""Scope search order"">).
993 <sect1>Structs, unions and enums<p>
995 Structs, unions and enums are explained in a <ref id="structs" name="separate
996 section">, I do only cover them here, because if they are declared with a
997 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
998 name=".SCOPE">/. However, when no name is specified, the behaviour is
999 different: In this case, no new scope will be opened, symbols declared within
1000 a struct, union, or enum declaration will then be added to the enclosing scope
1004 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1006 Accessing symbols from other scopes is possible by using an explicit scope
1007 specification, provided that the scope where the symbol lives in has a name.
1008 The namespace token (<tt/::/) is used to access other scopes:
1016 lda foo::bar ; Access foo in scope bar
1019 The only way to deny access to a scope from the outside is to declare a scope
1020 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1022 A special syntax is used to specify the global scope: If a symbol or scope is
1023 preceded by the namespace token, the global scope is searched:
1030 lda #::bar ; Access the global bar (which is 3)
1035 <sect1>Scope search order<label id="scopesearch"><p>
1037 The assembler searches for a scope in a similar way as for a symbol. First, it
1038 looks in the current scope, and then it walks up the enclosing scopes until
1041 However, one important thing to note when using explicit scope syntax is, that
1042 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1043 used without a preceding definition. This means that in the following
1052 lda #foo::bar ; Will load 3, not 2!
1059 the reference to the scope <tt/foo/ will use the global scope, and not the
1060 local one, because the local one is not visible at the point where it is
1063 Things get more complex if a complete chain of scopes is specified:
1074 lda #outer::inner::bar ; 1
1086 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1087 assembler will first search in the local scope for a scope named <tt/outer/.
1088 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1089 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1090 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1091 this scope, the assembler looks for a symbol named <tt/bar/.
1093 Please note that once the anchor scope is found, all following scopes
1094 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1095 assembler will search the scope tree only for the first scope (if it is not
1096 anchored in the root scope). Starting from there on, there is no flexibility,
1097 so if the scope named <tt/outer/ found by the assembler does not contain a
1098 scope named <tt/inner/, this would be an error, even if such a pair does exist
1099 (one level up in global scope).
1101 Ambiguities that may be introduced by this search algorithm may be removed by
1102 anchoring the scope specification in the global scope. In the example above,
1103 if you want to access the "other" symbol <tt/bar/, you would have to write:
1114 lda #::outer::inner::bar ; 2
1127 <sect>Address sizes and memory models<label id="address-sizes"><p>
1129 <sect1>Address sizes<p>
1131 ca65 assigns each segment and each symbol an address size. This is true, even
1132 if the symbol is not used as an address. You may also think of a value range
1133 of the symbol instead of an address size.
1135 Possible address sizes are:
1138 <item>Zeropage or direct (8 bits)
1139 <item>Absolute (16 bits)
1141 <item>Long (32 bits)
1144 Since the assembler uses default address sizes for the segments and symbols,
1145 it is usually not necessary to override the default behaviour. In cases, where
1146 it is necessary, the following keywords may be used to specify address sizes:
1149 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1150 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1151 <item>FAR for far addressing (24 bits).
1152 <item>LONG or DWORD for long addressing (32 bits).
1156 <sect1>Address sizes of segments<p>
1158 The assembler assigns an address size to each segment. Since the
1159 representation of a label within this segment is "segment start + offset",
1160 labels will inherit the address size of the segment they are declared in.
1162 The address size of a segment may be changed, by using an optional address
1163 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1164 an explanation on how this is done.
1167 <sect1>Address sizes of symbols<p>
1172 <sect1>Memory models<p>
1174 The default address size of a segment depends on the memory model used. Since
1175 labels inherit the address size from the segment they are declared in,
1176 changing the memory model is an easy way to change the address size of many
1182 <sect>Pseudo variables<label id="pseudo-variables"><p>
1184 Pseudo variables are readable in all cases, and in some special cases also
1187 <sect1><tt>*</tt><p>
1189 Reading this pseudo variable will return the program counter at the start
1190 of the current input line.
1192 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1193 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1194 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1197 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1199 Reading this pseudo variable will give a constant integer value that
1200 tells which CPU is currently enabled. It can also tell which instruction
1201 set the CPU is able to translate. The value read from the pseudo variable
1202 should be further examined by using one of the constants defined by the
1203 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1205 It may be used to replace the .IFPxx pseudo instructions or to construct
1206 even more complex expressions.
1212 .if (.cpu .bitand CPU_ISET_65816)
1224 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1226 This builtin pseudo variable is only available in macros. It is replaced by
1227 the actual number of parameters that were given in the macro invocation.
1232 .macro foo arg1, arg2, arg3
1233 .if .paramcount <> 3
1234 .error "Too few parameters for macro foo"
1240 See section <ref id="macros" name="Macros">.
1243 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1245 Reading this pseudo variable will give a constant integer value that
1246 represents the current time in POSIX standard (as seconds since the
1249 It may be used to encode the time of translation somewhere in the created
1255 .dword .time ; Place time here
1259 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1261 Reading this pseudo variable will give the assembler version according to
1262 the following formula:
1264 VER_MAJOR*$100 + VER_MINOR*$10
1266 It may be used to encode the assembler version or check the assembler for
1267 special features not available with older versions.
1271 Version 2.14 of the assembler will return $2E0 as numerical constant when
1272 reading the pseudo variable <tt/.VERSION/.
1276 <sect>Pseudo functions<label id="pseudo-functions"><p>
1278 Pseudo functions expect their arguments in parenthesis, and they have a result,
1279 either a string or an expression.
1282 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1284 The <tt/.BANK/ function is used to support systems with banked memory. The
1285 argument is an expression with exactly one segment reference - usually a
1286 label. The function result is the value of the <tt/bank/ attribute assigned
1287 to the run memory area of the segment. Please see the linker documentation
1288 for more information about memory areas and their attributes.
1290 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1291 containing specific data is available.
1293 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1294 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1295 name=".LOBYTE"></tt> or similar functions to address just part of it.
1297 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1298 an expression containing <tt/.BANK/ can never be used where a constant known
1299 result is expected (for example with <tt/.RES/).
1316 .byte <.BANK (banked_func_1)
1319 .byte <.BANK (banked_func_2)
1325 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1327 The function returns the bank byte (that is, bits 16-23) of its argument.
1328 It works identical to the '^' operator.
1330 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1331 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1334 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1336 Builtin function. The function evaluates its argument in braces and yields
1337 "false" if the argument is non blank (there is an argument), and "true" if
1338 there is no argument. The token list that makes up the function argument
1339 may optionally be enclosed in curly braces. This allows the inclusion of
1340 tokens that would otherwise terminate the list (the closing right
1341 parenthesis). The curly braces are not considered part of the list, a list
1342 just consisting of curly braces is considered to be empty.
1344 As an example, the <tt/.IFBLANK/ statement may be replaced by
1352 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1354 Builtin string function. The function allows to concatenate a list of string
1355 constants separated by commas. The result is a string constant that is the
1356 concatenation of all arguments. This function is most useful in macros and
1357 when used together with the <tt/.STRING/ builtin function. The function may
1358 be used in any case where a string constant is expected.
1363 .include .concat ("myheader", ".", "inc")
1366 This is the same as the command
1369 .include "myheader.inc"
1373 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1375 Builtin function. The function evaluates its argument in braces and
1376 yields "true" if the argument is a constant expression (that is, an
1377 expression that yields a constant value at assembly time) and "false"
1378 otherwise. As an example, the .IFCONST statement may be replaced by
1385 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1387 The function returns the high byte (that is, bits 8-15) of its argument.
1388 It works identical to the '>' operator.
1390 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1391 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1394 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1396 The function returns the high word (that is, bits 16-31) of its argument.
1398 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1401 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1403 The function expects a string as its argument, and converts this argument
1404 into an identifier. If the string starts with the current <tt/<ref
1405 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1406 identifier, otherwise it will be converted into a normal identifier.
1411 .macro makelabel arg1, arg2
1412 .ident (.concat (arg1, arg2)):
1415 makelabel "foo", "bar"
1417 .word foobar ; Valid label
1421 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1423 Builtin function. Extracts the left part of a given token list.
1428 .LEFT (<int expr>, <token list>)
1431 The first integer expression gives the number of tokens to extract from
1432 the token list. The second argument is the token list itself. The token
1433 list may optionally be enclosed into curly braces. This allows the
1434 inclusion of tokens that would otherwise terminate the list (the closing
1435 right paren in the given case).
1439 To check in a macro if the given argument has a '#' as first token
1440 (immediate addressing mode), use something like this:
1445 .if (.match (.left (1, {arg}), #))
1447 ; ldax called with immediate operand
1455 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1456 name=".RIGHT"></tt> builtin functions.
1459 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1461 The function returns the low byte (that is, bits 0-7) of its argument.
1462 It works identical to the '<' operator.
1464 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1465 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1468 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1470 The function returns the low word (that is, bits 0-15) of its argument.
1472 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1475 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1477 Builtin function. Matches two token lists against each other. This is
1478 most useful within macros, since macros are not stored as strings, but
1484 .MATCH(<token list #1>, <token list #2>)
1487 Both token list may contain arbitrary tokens with the exception of the
1488 terminator token (comma resp. right parenthesis) and
1495 The token lists may optionally be enclosed into curly braces. This allows
1496 the inclusion of tokens that would otherwise terminate the list (the closing
1497 right paren in the given case). Often a macro parameter is used for any of
1500 Please note that the function does only compare tokens, not token
1501 attributes. So any number is equal to any other number, regardless of the
1502 actual value. The same is true for strings. If you need to compare tokens
1503 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1504 name=".XMATCH"></tt> function.
1508 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1509 while honoring the sign bit. The builtin processor instructions will allow
1510 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1511 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1512 to check for this and print and error for invalid calls.
1517 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1518 .error "Syntax error"
1521 cmp #$80 ; Bit 7 into carry
1522 lsr a ; Shift carry into bit 7
1527 The macro will only accept no arguments, or one argument that must be the
1528 reserved keyword "A".
1530 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1533 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1535 Builtin function. The result is the larger of two values.
1540 .MAX (<value #1>, <value #2>)
1546 ; Reserve space for the larger of two data blocks
1547 savearea: .max (.sizeof (foo), .sizeof (bar))
1550 See: <tt><ref id=".MIN" name=".MIN"></tt>
1553 <sect1><tt>.MID</tt><label id=".MID"><p>
1555 Builtin function. Takes a starting index, a count and a token list as
1556 arguments. Will return part of the token list.
1561 .MID (<int expr>, <int expr>, <token list>)
1564 The first integer expression gives the starting token in the list (the first
1565 token has index 0). The second integer expression gives the number of tokens
1566 to extract from the token list. The third argument is the token list itself.
1567 The token list may optionally be enclosed into curly braces. This allows the
1568 inclusion of tokens that would otherwise terminate the list (the closing
1569 right paren in the given case).
1573 To check in a macro if the given argument has a '<tt/#/' as first token
1574 (immediate addressing mode), use something like this:
1579 .if (.match (.mid (0, 1, {arg}), #))
1581 ; ldax called with immediate operand
1589 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1590 name=".RIGHT"></tt> builtin functions.
1593 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1595 Builtin function. The result is the smaller of two values.
1600 .MIN (<value #1>, <value #2>)
1606 ; Reserve space for some data, but 256 bytes minimum
1607 savearea: .min (.sizeof (foo), 256)
1610 See: <tt><ref id=".MAX" name=".MAX"></tt>
1613 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1615 Builtin function. The function expects an identifier as argument in braces.
1616 The argument is evaluated, and the function yields "true" if the identifier
1617 is a symbol that has already been referenced somewhere in the source file up
1618 to the current position. Otherwise the function yields false. As an example,
1619 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1625 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1628 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1630 Builtin function. Extracts the right part of a given token list.
1635 .RIGHT (<int expr>, <token list>)
1638 The first integer expression gives the number of tokens to extract from the
1639 token list. The second argument is the token list itself. The token list
1640 may optionally be enclosed into curly braces. This allows the inclusion of
1641 tokens that would otherwise terminate the list (the closing right paren in
1644 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1645 name=".MID"></tt> builtin functions.
1648 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1650 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1651 argument can be a struct/union, a struct member, a procedure, or a label. In
1652 case of a procedure or label, its size is defined by the amount of data
1653 placed in the segment where the label is relative to. If a line of code
1654 switches segments (for example in a macro) data placed in other segments
1655 does not count for the size.
1657 Please note that a symbol or scope must exist, before it is used together with
1658 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1659 A scope has preference over a symbol with the same name, so if the last part
1660 of a name represents both, a scope and a symbol, the scope is chosen over the
1663 After the following code:
1666 .struct Point ; Struct size = 4
1671 P: .tag Point ; Declare a point
1672 @P: .tag Point ; Declare another point
1684 .data ; Segment switch!!!
1690 <tag><tt/.sizeof(Point)/</tag>
1691 will have the value 4, because this is the size of struct <tt/Point/.
1693 <tag><tt/.sizeof(Point::xcoord)/</tag>
1694 will have the value 2, because this is the size of the member <tt/xcoord/
1695 in struct <tt/Point/.
1697 <tag><tt/.sizeof(P)/</tag>
1698 will have the value 4, this is the size of the data declared on the same
1699 source line as the label <tt/P/, which is in the same segment that <tt/P/
1702 <tag><tt/.sizeof(@P)/</tag>
1703 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1704 does also work for cheap local symbols.
1706 <tag><tt/.sizeof(Code)/</tag>
1707 will have the value 3, since this is amount of data emitted into the code
1708 segment, the segment that was active when <tt/Code/ was entered. Note that
1709 this value includes the amount of data emitted in child scopes (in this
1710 case <tt/Code::Inner/).
1712 <tag><tt/.sizeof(Code::Inner)/</tag>
1713 will have the value 1 as expected.
1715 <tag><tt/.sizeof(Data)/</tag>
1716 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1717 the segment is switched after entry, this data is emitted into another
1722 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1724 Builtin function. The function accepts a string and an index as
1725 arguments and returns the value of the character at the given position
1726 as an integer value. The index is zero based.
1732 ; Check if the argument string starts with '#'
1733 .if (.strat (Arg, 0) = '#')
1740 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1742 Builtin function. It expects a format string as first argument. The number
1743 and type of the following arguments depend on the format string. The format
1744 string is similar to the one of the C <tt/printf/ function. Missing things
1745 are: Length modifiers, variable width.
1747 The result of the function is a string.
1754 ; Generate an identifier:
1755 .ident (.sprintf ("%s%03d", "label", num)):
1759 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1761 Builtin function. The function accepts an argument in braces and converts
1762 this argument into a string constant. The argument may be an identifier, or
1763 a constant numeric value.
1765 Since you can use a string in the first place, the use of the function may
1766 not be obvious. However, it is useful in macros, or more complex setups.
1771 ; Emulate other assemblers:
1773 .segment .string(name)
1778 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1780 Builtin function. The function accepts a string argument in braces and
1781 evaluates to the length of the string.
1785 The following macro encodes a string as a pascal style string with
1786 a leading length byte.
1790 .byte .strlen(Arg), Arg
1795 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1797 Builtin function. The function accepts a token list in braces. The function
1798 result is the number of tokens given as argument. The token list may
1799 optionally be enclosed into curly braces which are not considered part of
1800 the list and not counted. Enclosement in curly braces allows the inclusion
1801 of tokens that would otherwise terminate the list (the closing right paren
1806 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1807 with the normal 6502 instructions). To translate it into two separate 8 bit
1808 load instructions, the '#' token has to get stripped from the argument:
1812 .if (.match (.mid (0, 1, {arg}), #))
1813 ; ldax called with immediate operand
1814 lda #<(.right (.tcount ({arg})-1, {arg}))
1815 ldx #>(.right (.tcount ({arg})-1, {arg}))
1823 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1825 Builtin function. Matches two token lists against each other. This is
1826 most useful within macros, since macros are not stored as strings, but
1832 .XMATCH(<token list #1>, <token list #2>)
1835 Both token list may contain arbitrary tokens with the exception of the
1836 terminator token (comma resp. right parenthesis) and
1843 The token lists may optionally be enclosed into curly braces. This allows
1844 the inclusion of tokens that would otherwise terminate the list (the closing
1845 right paren in the given case). Often a macro parameter is used for any of
1848 The function compares tokens <em/and/ token values. If you need a function
1849 that just compares the type of tokens, have a look at the <tt><ref
1850 id=".MATCH" name=".MATCH"></tt> function.
1852 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1856 <sect>Control commands<label id="control-commands"><p>
1858 Here's a list of all control commands and a description, what they do:
1861 <sect1><tt>.A16</tt><label id=".A16"><p>
1863 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1865 Note: This command will not emit any code, it will tell the assembler to
1866 create 16 bit operands for immediate accumulator addressing mode.
1868 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1871 <sect1><tt>.A8</tt><label id=".A8"><p>
1873 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1875 Note: This command will not emit any code, it will tell the assembler to
1876 create 8 bit operands for immediate accu addressing mode.
1878 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1881 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1883 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1884 may be used for better readability if the data words are address values. In
1885 65816 mode, the address is forced to be 16 bit wide to fit into the current
1886 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1887 must be followed by a sequence of (not necessarily constant) expressions.
1892 .addr $0D00, $AF13, _Clear
1895 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1899 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1901 Align data to a given boundary. The command expects a constant integer
1902 argument in the range 1 ... 65536, plus an optional second argument
1903 in byte range. If there is a second argument, it is used as fill value,
1904 otherwise the value defined in the linker configuration file is used
1905 (the default for this value is zero).
1907 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1908 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1909 number of bytes, since that would break address calculations within the
1910 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1911 of the alignment, because that allows the number of fill bytes to be
1912 calculated in advance by the assembler. You are therefore required to
1913 specify a matching alignment for the segment in the linker config. The
1914 linker will output a warning if the alignment of the segment is less than
1915 what is necessary to have a correct alignment in the object file.
1923 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1924 commands with different arguments. To allow the assembler to calculate the
1925 number of fill bytes in advance, the alignment of the segment must be a
1926 multiple of each of the alignment factors. This may result in unexpectedly
1927 large alignments for the segment within the module.
1938 For the assembler to be able to align correctly, the segment must be aligned
1939 to the least common multiple of 15 and 18 which is 90. The assembler will
1940 calculate this automatically and will mark the segment with this value.
1942 Unfortunately, the combined alignment may get rather large without the user
1943 knowing about it, wasting space in the final executable. If we add another
1944 alignment to the example above
1955 the assembler will force a segment alignment to the least common multiple of
1956 15, 18 and 251 - which is 22590. To protect the user against errors, the
1957 assembler will issue a warning when the combined alignment exceeds 256. The
1958 command line option <tt><ref id="option--large-alignment"
1959 name="--large-alignment"></tt> will disable this warning.
1961 Please note that with alignments that are a power of two (which were the
1962 only alignments possible in older versions of the assembler), the problem is
1963 less severe, because the least common multiple of powers to the same base is
1964 always the larger one.
1968 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1970 Define a string with a trailing zero.
1975 Msg: .asciiz "Hello world"
1978 This will put the string "Hello world" followed by a binary zero into
1979 the current segment. There may be more strings separated by commas, but
1980 the binary zero is only appended once (after the last one).
1983 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1985 Add an assertion. The command is followed by an expression, an action
1986 specifier, and an optional message that is output in case the assertion
1987 fails. If no message was given, the string "Assertion failed" is used. The
1988 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
1989 <tt/lderror/. In the former two cases, the assertion is evaluated by the
1990 assembler if possible, and in any case, it's also passed to the linker in
1991 the object file (if one is generated). The linker will then evaluate the
1992 expression when segment placement has been done.
1997 .assert * = $8000, error, "Code not at $8000"
2000 The example assertion will check that the current location is at $8000,
2001 when the output file is written, and abort with an error if this is not
2002 the case. More complex expressions are possible. The action specifier
2003 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2004 an error message. In the latter case, generation of the output file is
2005 suppressed in both the assembler and linker.
2008 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2010 Is followed by a plus or a minus character. When switched on (using a
2011 +), undefined symbols are automatically marked as import instead of
2012 giving errors. When switched off (which is the default so this does not
2013 make much sense), this does not happen and an error message is
2014 displayed. The state of the autoimport flag is evaluated when the
2015 complete source was translated, before outputting actual code, so it is
2016 <em/not/ possible to switch this feature on or off for separate sections
2017 of code. The last setting is used for all symbols.
2019 You should probably not use this switch because it delays error
2020 messages about undefined symbols until the link stage. The cc65
2021 compiler (which is supposed to produce correct assembler code in all
2022 circumstances, something which is not true for most assembler
2023 programmers) will insert this command to avoid importing each and every
2024 routine from the runtime library.
2029 .autoimport + ; Switch on auto import
2032 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2034 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2035 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2036 the operator '^' prepended to each expression in its list.
2041 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2043 TableLookupLo: .lobytes MyTable
2044 TableLookupHi: .hibytes MyTable
2045 TableLookupBank: .bankbytes MyTable
2048 which is equivalent to
2051 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2052 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2053 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2056 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2057 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2058 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2061 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2063 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2064 so this is a shortcut for
2070 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2073 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2075 Define byte sized data. Must be followed by a sequence of (byte ranged)
2076 expressions or strings.
2082 .byt "world", $0D, $00
2086 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2088 Switch on or off case sensitivity on identifiers. The default is off
2089 (that is, identifiers are case sensitive), but may be changed by the
2090 -i switch on the command line.
2091 The command must be followed by a '+' or '-' character to switch the
2092 option on or off respectively.
2097 .case - ; Identifiers are not case sensitive
2101 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2103 Apply a custom mapping for characters. The command is followed by two
2104 numbers. The first one is the index of the source character (range 1..255),
2105 the second one is the mapping (range 0..255). The mapping applies to all
2106 character and string constants when they generate output, and overrides a
2107 mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2108 command line switch.
2113 .charmap $41, $61 ; Map 'A' to 'a'
2117 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2119 Switch to the CODE segment. The name of the CODE segment is always
2120 "CODE", so this is a shortcut for
2126 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2129 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2131 Export a symbol and mark it in a special way. The linker is able to build
2132 tables of all such symbols. This may be used to automatically create a list
2133 of functions needed to initialize linked library modules.
2135 Note: The linker has a feature to build a table of marked routines, but it
2136 is your code that must call these routines, so just declaring a symbol with
2137 <tt/.CONDES/ does nothing by itself.
2139 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2140 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2141 is implied by <tt/.CONDES/.
2143 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2144 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2145 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2146 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2147 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2148 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2149 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2151 After the type, an optional priority may be specified. Higher numeric values
2152 mean higher priority. If no priority is given, the default priority of 7 is
2153 used. Be careful when assigning priorities to your own module constructors
2154 so they won't interfere with the ones in the cc65 library.
2159 .condes ModuleInit, constructor
2160 .condes ModInit, 0, 16
2163 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2164 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2165 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2166 name="Module constructors/destructors"> explaining the feature in more
2170 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2172 Export a symbol and mark it as a module constructor. This may be used
2173 together with the linker to build a table of constructor subroutines that
2174 are called by the startup code.
2176 Note: The linker has a feature to build a table of marked routines, but it
2177 is your code that must call these routines, so just declaring a symbol as
2178 constructor does nothing by itself.
2180 A constructor is always exported as an absolute (16 bit) symbol. You don't
2181 need to use an additional <tt/.export/ statement, this is implied by
2182 <tt/.constructor/. It may have an optional priority that is separated by a
2183 comma. Higher numeric values mean a higher priority. If no priority is
2184 given, the default priority of 7 is used. Be careful when assigning
2185 priorities to your own module constructors so they won't interfere with the
2186 ones in the cc65 library.
2191 .constructor ModuleInit
2192 .constructor ModInit, 16
2195 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2196 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2197 <ref id="condes" name="Module constructors/destructors"> explaining the
2198 feature in more detail.
2201 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2203 Switch to the DATA segment. The name of the DATA segment is always
2204 "DATA", so this is a shortcut for
2210 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2213 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2215 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2216 create word sized data in native 65XX format). Must be followed by a
2217 sequence of (word ranged) expressions.
2225 This will emit the bytes
2231 into the current segment in that order.
2234 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2236 Switch on or off debug info generation. The default is off (that is,
2237 the object file will not contain debug infos), but may be changed by the
2238 -g switch on the command line.
2239 The command must be followed by a '+' or '-' character to switch the
2240 option on or off respectively.
2245 .debuginfo + ; Generate debug info
2249 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2251 Start a define style macro definition. The command is followed by an
2252 identifier (the macro name) and optionally by a list of formal arguments
2255 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2256 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2259 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2260 section <ref id="macros" name="Macros">.
2263 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2265 Delete a classic macro (defined with <tt><ref id=".MACRO"
2266 name=".MACRO"></tt>) . The command is followed by the name of an
2267 existing macro. Its definition will be deleted together with the name.
2268 If necessary, another macro with this name may be defined later.
2270 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2271 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2272 <tt><ref id=".MACRO" name=".MACRO"></tt>
2274 See also section <ref id="macros" name="Macros">.
2277 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2279 Builtin function. The function expects an identifier as argument in braces.
2280 The argument is evaluated, and the function yields "true" if the identifier
2281 is a symbol that is already defined somewhere in the source file up to the
2282 current position. Otherwise the function yields false. As an example, the
2283 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2290 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2292 Export a symbol and mark it as a module destructor. This may be used
2293 together with the linker to build a table of destructor subroutines that
2294 are called by the startup code.
2296 Note: The linker has a feature to build a table of marked routines, but it
2297 is your code that must call these routines, so just declaring a symbol as
2298 constructor does nothing by itself.
2300 A destructor is always exported as an absolute (16 bit) symbol. You don't
2301 need to use an additional <tt/.export/ statement, this is implied by
2302 <tt/.destructor/. It may have an optional priority that is separated by a
2303 comma. Higher numerical values mean a higher priority. If no priority is
2304 given, the default priority of 7 is used. Be careful when assigning
2305 priorities to your own module destructors so they won't interfere with the
2306 ones in the cc65 library.
2311 .destructor ModuleDone
2312 .destructor ModDone, 16
2315 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2316 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2317 section <ref id="condes" name="Module constructors/destructors"> explaining
2318 the feature in more detail.
2321 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2323 Define dword sized data (4 bytes) Must be followed by a sequence of
2329 .dword $12344512, $12FA489
2333 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2335 Conditional assembly: Reverse the current condition.
2338 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2340 Conditional assembly: Reverse current condition and test a new one.
2343 <sect1><tt>.END</tt><label id=".END"><p>
2345 Forced end of assembly. Assembly stops at this point, even if the command
2346 is read from an include file.
2349 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2351 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2354 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2356 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2357 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2360 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2362 Marks the end of a macro definition.
2364 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2365 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2366 <tt><ref id=".MACRO" name=".MACRO"></tt>
2368 See also section <ref id="macros" name="Macros">.
2371 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2373 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2376 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2378 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2381 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2383 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2386 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2388 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2389 command and the separate section named <ref id="structs" name=""Structs
2393 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2395 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2396 command and the separate section named <ref id="structs" name=""Structs
2400 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2402 Start an enumeration. This directive is very similar to the C <tt/enum/
2403 keyword. If a name is given, a new scope is created for the enumeration,
2404 otherwise the enumeration members are placed in the enclosing scope.
2406 In the enumeration body, symbols are declared. The first symbol has a value
2407 of zero, and each following symbol will get the value of the preceding plus
2408 one. This behaviour may be overridden by an explicit assignment. Two symbols
2409 may have the same value.
2421 Above example will create a new scope named <tt/errorcodes/ with three
2422 symbols in it that get the values 0, 1 and 2 respectively. Another way
2423 to write this would have been:
2433 Please note that explicit scoping must be used to access the identifiers:
2436 .word errorcodes::no_error
2439 A more complex example:
2448 EWOULDBLOCK = EAGAIN
2452 In this example, the enumeration does not have a name, which means that the
2453 members will be visible in the enclosing scope and can be used in this scope
2454 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2455 The value for the following members is incremented by one, so <tt/EOK/ would
2456 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2457 override for the value using an already defined symbol.
2460 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2462 Force an assembly error. The assembler will output an error message
2463 preceded by "User error". Assembly is continued but no object file will
2466 This command may be used to check for initial conditions that must be
2467 set before assembling a source file.
2477 .error "Must define foo or bar!"
2481 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2482 <tt><ref id=".OUT" name=".OUT"></tt>,
2483 <tt><ref id=".WARNING" name=".WARNING"></tt>
2486 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2488 Abort a macro expansion immediately. This command is often useful in
2491 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2492 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2493 <tt><ref id=".MACRO" name=".MACRO"></tt>
2495 See also section <ref id="macros" name="Macros">.
2498 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2500 Make symbols accessible from other modules. Must be followed by a comma
2501 separated list of symbols to export, with each one optionally followed by an
2502 address specification and (also optional) an assignment. Using an additional
2503 assignment in the export statement allows to define and export a symbol in
2504 one statement. The default is to export the symbol with the address size it
2505 actually has. The assembler will issue a warning, if the symbol is exported
2506 with an address size smaller than the actual address size.
2513 .export foobar: far = foo * bar
2514 .export baz := foobar, zap: far = baz - bar
2517 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2520 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2523 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2525 Make symbols accessible from other modules. Must be followed by a comma
2526 separated list of symbols to export. The exported symbols are explicitly
2527 marked as zero page symbols. An assignment may be included in the
2528 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2535 .exportzp baz := $02
2538 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2541 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2543 Define far (24 bit) address data. The command must be followed by a
2544 sequence of (not necessarily constant) expressions.
2549 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2552 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2555 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2557 Force an assembly error and terminate assembly. The assembler will output an
2558 error message preceded by "User error" and will terminate assembly
2561 This command may be used to check for initial conditions that must be
2562 set before assembling a source file.
2572 .fatal "Must define foo or bar!"
2576 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2577 <tt><ref id=".OUT" name=".OUT"></tt>,
2578 <tt><ref id=".WARNING" name=".WARNING"></tt>
2581 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2583 This directive may be used to enable one or more compatibility features
2584 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2585 possible, it may be useful when porting sources written for other
2586 assemblers. There is no way to switch a feature off, once you have
2587 enabled it, so using
2593 will enable the feature until end of assembly is reached.
2595 The following features are available:
2599 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2601 Accept the at character (`@') as a valid character in identifiers. The
2602 at character is not allowed to start an identifier, even with this
2605 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2607 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2608 comment terminators. Note that C comments may not be nested. There's also a
2609 pitfall when using C like comments: All statements must be terminated by
2610 "end-of-line". Using C like comments, it is possible to hide the newline,
2611 which results in error messages. See the following non working example:
2614 lda #$00 /* This comment hides the newline
2618 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2620 Accept the dollar sign (`$') as a valid character in identifiers. The
2621 dollar character is not allowed to start an identifier, even with this
2624 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2626 The dollar sign may be used as an alias for the star (`*'), which
2627 gives the value of the current PC in expressions.
2628 Note: Assignment to the pseudo variable is not allowed.
2630 <tag><tt>force_range</tt><label id="force_range"></tag>
2632 Force expressions into their valid range for immediate addressing and
2633 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2634 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2635 since it will completely disable error checks.
2637 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2639 Allow labels without a trailing colon. These labels are only accepted,
2640 if they start at the beginning of a line (no leading white space).
2642 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2644 Accept the dot (`.') as the first character of an identifier. This may be
2645 used for example to create macro names that start with a dot emulating
2646 control directives of other assemblers. Note however, that none of the
2647 reserved keywords built into the assembler, that starts with a dot, may be
2648 overridden. When using this feature, you may also get into trouble if
2649 later versions of the assembler define new keywords starting with a dot.
2651 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2653 Accept single quotes as well as double quotes as terminators for char
2656 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2658 Accept single quotes as well as double quotes as terminators for string
2661 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2663 Accept single quoted character constants where the terminating quote is
2668 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2669 loose_string_term/, since in this case the input would be ambiguous.
2671 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2673 This feature makes relocatable/absolute mode local to the current segment.
2674 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2675 effect will only enable absolute mode for the current segment. Dito for
2676 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2678 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2680 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2681 is enabled). Such an assignment is handled identical to the <tt><ref
2682 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2683 removing the lines with the assignments may also be an option when porting
2684 code written for older assemblers).
2686 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2688 Allow the use of instructions names as names for macros and symbols. This
2689 makes it possible to "overload" instructions by defining a macro with the
2690 same name. This does also make it possible to introduce hard to find errors
2691 in your code, so be careful!
2693 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2695 Allow underlines within numeric constants. These may be used for grouping
2696 the digits of numbers for easier reading.
2699 .feature underline_in_numbers
2700 .word %1100001110100101
2701 .word %1100_0011_1010_0101 ; Identical but easier to read
2706 It is also possible to specify features on the command line using the
2707 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2708 This is useful when translating sources written for older assemblers, when
2709 you don't want to change the source code.
2711 As an example, to translate sources written for Andre Fachats xa65
2712 assembler, the features
2715 labels_without_colons, pc_assignment, loose_char_term
2718 may be helpful. They do not make ca65 completely compatible, so you may not
2719 be able to translate the sources without changes, even when enabling these
2720 features. However, I have found several sources that translate without
2721 problems when enabling these features on the command line.
2724 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2726 Insert an option string into the object file. There are two forms of
2727 this command, one specifies the option by a keyword, the second
2728 specifies it as a number. Since usage of the second one needs knowledge
2729 of the internal encoding, its use is not recommended and I will only
2730 describe the first form here.
2732 The command is followed by one of the keywords
2740 a comma and a string. The option is written into the object file
2741 together with the string value. This is currently unidirectional and
2742 there is no way to actually use these options once they are in the
2748 .fileopt comment, "Code stolen from my brother"
2749 .fileopt compiler, "BASIC 2.0"
2750 .fopt author, "J. R. User"
2754 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2756 Import an absolute symbol from another module. The command is followed by a
2757 comma separated list of symbols to import. The command is similar to <tt>
2758 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2759 written to the generated object file, even if the symbol is never referenced
2760 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2761 references for unused symbols).
2766 .forceimport needthisone, needthistoo
2769 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2772 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2774 Declare symbols as global. Must be followed by a comma separated list of
2775 symbols to declare. Symbols from the list, that are defined somewhere in the
2776 source, are exported, all others are imported. Additional <tt><ref
2777 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2778 name=".EXPORT"></tt> commands for the same symbol are allowed.
2787 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2789 Declare symbols as global. Must be followed by a comma separated list of
2790 symbols to declare. Symbols from the list, that are defined somewhere in the
2791 source, are exported, all others are imported. Additional <tt><ref
2792 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2793 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2794 in the list are explicitly marked as zero page symbols.
2802 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2804 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2805 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2806 the operator '>' prepended to each expression in its list.
2811 .lobytes $1234, $2345, $3456, $4567
2812 .hibytes $fedc, $edcb, $dcba, $cba9
2815 which is equivalent to
2818 .byte $34, $45, $56, $67
2819 .byte $fe, $ed, $dc, $cb
2825 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2827 TableLookupLo: .lobytes MyTable
2828 TableLookupHi: .hibytes MyTable
2831 which is equivalent to
2834 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2835 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2838 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2839 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2840 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2843 <sect1><tt>.I16</tt><label id=".I16"><p>
2845 Valid only in 65816 mode. Switch the index registers to 16 bit.
2847 Note: This command will not emit any code, it will tell the assembler to
2848 create 16 bit operands for immediate operands.
2850 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2851 name=".SMART"></tt> commands.
2854 <sect1><tt>.I8</tt><label id=".I8"><p>
2856 Valid only in 65816 mode. Switch the index registers to 8 bit.
2858 Note: This command will not emit any code, it will tell the assembler to
2859 create 8 bit operands for immediate operands.
2861 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2862 name=".SMART"></tt> commands.
2865 <sect1><tt>.IF</tt><label id=".IF"><p>
2867 Conditional assembly: Evaluate an expression and switch assembler output
2868 on or off depending on the expression. The expression must be a constant
2869 expression, that is, all operands must be defined.
2871 A expression value of zero evaluates to FALSE, any other value evaluates
2875 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2877 Conditional assembly: Check if there are any remaining tokens in this line,
2878 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2879 condition is not true, further lines are not assembled until an <tt><ref
2880 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2881 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2883 This command is often used to check if a macro parameter was given. Since an
2884 empty macro parameter will evaluate to nothing, the condition will evaluate
2885 to TRUE if an empty parameter was given.
2899 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2902 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2904 Conditional assembly: Evaluate an expression and switch assembler output
2905 on or off depending on the constness of the expression.
2907 A const expression evaluates to to TRUE, a non const expression (one
2908 containing an imported or currently undefined symbol) evaluates to
2911 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2914 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2916 Conditional assembly: Check if a symbol is defined. Must be followed by
2917 a symbol name. The condition is true if the the given symbol is already
2918 defined, and false otherwise.
2920 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2923 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2925 Conditional assembly: Check if there are any remaining tokens in this line,
2926 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2927 condition is not true, further lines are not assembled until an <tt><ref
2928 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2929 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2931 This command is often used to check if a macro parameter was given.
2932 Since an empty macro parameter will evaluate to nothing, the condition
2933 will evaluate to FALSE if an empty parameter was given.
2946 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2949 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2951 Conditional assembly: Check if a symbol is defined. Must be followed by
2952 a symbol name. The condition is true if the the given symbol is not
2953 defined, and false otherwise.
2955 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2958 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2960 Conditional assembly: Check if a symbol is referenced. Must be followed
2961 by a symbol name. The condition is true if if the the given symbol was
2962 not referenced before, and false otherwise.
2964 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2967 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2969 Conditional assembly: Check if the assembler is currently in 6502 mode
2970 (see <tt><ref id=".P02" name=".P02"></tt> command).
2973 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2975 Conditional assembly: Check if the assembler is currently in 65816 mode
2976 (see <tt><ref id=".P816" name=".P816"></tt> command).
2979 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2981 Conditional assembly: Check if the assembler is currently in 65C02 mode
2982 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2985 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2987 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2988 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2991 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2993 Conditional assembly: Check if a symbol is referenced. Must be followed
2994 by a symbol name. The condition is true if if the the given symbol was
2995 referenced before, and false otherwise.
2997 This command may be used to build subroutine libraries in include files
2998 (you may use separate object modules for this purpose too).
3003 .ifref ToHex ; If someone used this subroutine
3004 ToHex: tay ; Define subroutine
3010 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3013 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3015 Import a symbol from another module. The command is followed by a comma
3016 separated list of symbols to import, with each one optionally followed by
3017 an address specification.
3023 .import bar: zeropage
3026 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3029 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3031 Import a symbol from another module. The command is followed by a comma
3032 separated list of symbols to import. The symbols are explicitly imported
3033 as zero page symbols (that is, symbols with values in byte range).
3041 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3044 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3046 Include a file as binary data. The command expects a string argument
3047 that is the name of a file to include literally in the current segment.
3048 In addition to that, a start offset and a size value may be specified,
3049 separated by commas. If no size is specified, all of the file from the
3050 start offset to end-of-file is used. If no start position is specified
3051 either, zero is assumed (which means that the whole file is inserted).
3056 ; Include whole file
3057 .incbin "sprites.dat"
3059 ; Include file starting at offset 256
3060 .incbin "music.dat", $100
3062 ; Read 100 bytes starting at offset 200
3063 .incbin "graphics.dat", 200, 100
3067 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3069 Include another file. Include files may be nested up to a depth of 16.
3078 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3080 Export a symbol and mark it as an interruptor. This may be used together
3081 with the linker to build a table of interruptor subroutines that are called
3084 Note: The linker has a feature to build a table of marked routines, but it
3085 is your code that must call these routines, so just declaring a symbol as
3086 interruptor does nothing by itself.
3088 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3089 need to use an additional <tt/.export/ statement, this is implied by
3090 <tt/.interruptor/. It may have an optional priority that is separated by a
3091 comma. Higher numeric values mean a higher priority. If no priority is
3092 given, the default priority of 7 is used. Be careful when assigning
3093 priorities to your own module constructors so they won't interfere with the
3094 ones in the cc65 library.
3099 .interruptor IrqHandler
3100 .interruptor Handler, 16
3103 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3104 section <ref id="condes" name="Module constructors/destructors"> explaining
3105 the feature in more detail.
3108 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3110 Switch on or off line continuations using the backslash character
3111 before a newline. The option is off by default.
3112 Note: Line continuations do not work in a comment. A backslash at the
3113 end of a comment is treated as part of the comment and does not trigger
3115 The command must be followed by a '+' or '-' character to switch the
3116 option on or off respectively.
3121 .linecont + ; Allow line continuations
3124 #$20 ; This is legal now
3128 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3130 Enable output to the listing. The command must be followed by a boolean
3131 switch ("on", "off", "+" or "-") and will enable or disable listing
3133 The option has no effect if the listing is not enabled by the command line
3134 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3135 to the listing file, if the counter is greater than zero, and suppressed if
3136 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3142 .list on ; Enable listing output
3146 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3148 Set, how many bytes are shown in the listing for one source line. The
3149 default is 12, so the listing will show only the first 12 bytes for any
3150 source line that generates more than 12 bytes of code or data.
3151 The directive needs an argument, which is either "unlimited", or an
3152 integer constant in the range 4..255.
3157 .listbytes unlimited ; List all bytes
3158 .listbytes 12 ; List the first 12 bytes
3159 .incbin "data.bin" ; Include large binary file
3163 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3165 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3166 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3167 the operator '<' prepended to each expression in its list.
3172 .lobytes $1234, $2345, $3456, $4567
3173 .hibytes $fedc, $edcb, $dcba, $cba9
3176 which is equivalent to
3179 .byte $34, $45, $56, $67
3180 .byte $fe, $ed, $dc, $cb
3186 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3188 TableLookupLo: .lobytes MyTable
3189 TableLookupHi: .hibytes MyTable
3192 which is equivalent to
3195 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3196 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3199 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3200 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3201 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3204 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3206 This command may only be used inside a macro definition. It declares a
3207 list of identifiers as local to the macro expansion.
3209 A problem when using macros are labels: Since they don't change their name,
3210 you get a "duplicate symbol" error if the macro is expanded the second time.
3211 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3212 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3215 Some other assemblers start a new lexical block inside a macro expansion.
3216 This has some drawbacks however, since that will not allow <em/any/ symbol
3217 to be visible outside a macro, a feature that is sometimes useful. The
3218 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3219 to address the problem.
3221 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3225 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3227 Defines the character that start "cheap" local labels. You may use one
3228 of '@' and '?' as start character. The default is '@'.
3230 Cheap local labels are labels that are visible only between two non
3231 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3232 using explicit lexical nesting.
3239 Clear: lda #$00 ; Global label
3240 ?Loop: sta Mem,y ; Local label
3244 Sub: ... ; New global label
3245 bne ?Loop ; ERROR: Unknown identifier!
3249 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3251 Insert a predefined macro package. The command is followed by an
3252 identifier specifying the macro package to insert. Available macro
3256 atari Defines the scrcode macro.
3257 cbm Defines the scrcode macro.
3258 cpu Defines constants for the .CPU variable.
3259 generic Defines generic macros like add and sub.
3260 longbranch Defines conditional long jump macros.
3263 Including a macro package twice, or including a macro package that
3264 redefines already existing macros will lead to an error.
3269 .macpack longbranch ; Include macro package
3271 cmp #$20 ; Set condition codes
3272 jne Label ; Jump long on condition
3275 Macro packages are explained in more detail in section <ref
3276 id="macropackages" name="Macro packages">.
3279 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3281 Start a classic macro definition. The command is followed by an identifier
3282 (the macro name) and optionally by a comma separated list of identifiers
3283 that are macro parameters. A macro definition is terminated by <tt><ref
3284 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3289 .macro ldax arg ; Define macro ldax
3294 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3295 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3296 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3298 See also section <ref id="macros" name="Macros">.
3301 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3303 Start a section of absolute code. The command is followed by a constant
3304 expression that gives the new PC counter location for which the code is
3305 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3308 By default, absolute/relocatable mode is global (valid even when switching
3309 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3310 it can be made segment local.
3312 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3313 code at a specific address is the job of the linker, not the assembler, so
3314 there is usually no reason to assemble code to a specific address.
3319 .org $7FF ; Emit code starting at $7FF
3323 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3325 Output a string to the console without producing an error. This command
3326 is similar to <tt/.ERROR/, however, it does not force an assembler error
3327 that prevents the creation of an object file.
3332 .out "This code was written by the codebuster(tm)"
3335 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3336 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3337 <tt><ref id=".WARNING" name=".WARNING"></tt>
3340 <sect1><tt>.P02</tt><label id=".P02"><p>
3342 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3343 instructions. This is the default if not overridden by the
3344 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3346 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3347 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3350 <sect1><tt>.P816</tt><label id=".P816"><p>
3352 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3353 6502 instruction sets.
3355 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3356 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3359 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3361 Set the page length for the listing. Must be followed by an integer
3362 constant. The value may be "unlimited", or in the range 32 to 127. The
3363 statement has no effect if no listing is generated. The default value is -1
3364 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3365 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3366 after assembly is complete, you cannot use multiple line lengths with one
3367 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3372 .pagelength 66 ; Use 66 lines per listing page
3374 .pagelength unlimited ; Unlimited page length
3378 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3380 Enable the 65C02 instructions set. This instruction set includes all
3381 6502 and 65SC02 instructions.
3383 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3384 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3387 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3389 Pop the last CPU setting from the stack, and activate it.
3391 This command will switch back to the CPU that was last pushed onto the CPU
3392 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3393 remove this entry from the stack.
3395 The assembler will print an error message if the CPU stack is empty when
3396 this command is issued.
3398 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3399 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3402 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3404 Pop the last pushed segment from the stack, and set it.
3406 This command will switch back to the segment that was last pushed onto the
3407 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3408 command, and remove this entry from the stack.
3410 The assembler will print an error message if the segment stack is empty
3411 when this command is issued.
3413 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3416 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3418 Start a nested lexical level with the given name and adds a symbol with this
3419 name to the enclosing scope. All new symbols from now on are in the local
3420 lexical level and are accessible from outside only via <ref id="scopesyntax"
3421 name="explicit scope specification">. Symbols defined outside this local
3422 level may be accessed as long as their names are not used for new symbols
3423 inside the level. Symbols names in other lexical levels do not clash, so you
3424 may use the same names for identifiers. The lexical level ends when the
3425 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3426 may be nested up to a depth of 16 (this is an artificial limit to protect
3427 against errors in the source).
3429 Note: Macro names are always in the global level and in a separate name
3430 space. There is no special reason for this, it's just that I've never
3431 had any need for local macro definitions.
3436 .proc Clear ; Define Clear subroutine, start new level
3438 L1: sta Mem,y ; L1 is local and does not cause a
3439 ; duplicate symbol error if used in other
3442 bne L1 ; Reference local symbol
3444 .endproc ; Leave lexical level
3447 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3451 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3453 Enable the 65SC02 instructions set. This instruction set includes all
3456 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3457 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3460 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3462 Push the currently active CPU onto a stack. The stack has a size of 8
3465 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3466 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3467 later, without knowledge of the current CPU setting.
3469 The assembler will print an error message if the CPU stack is already full,
3470 when this command is issued.
3472 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3473 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3476 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3478 Push the currently active segment onto a stack. The entries on the stack
3479 include the name of the segment and the segment type. The stack has a size
3482 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3483 to switch to another segment and to restore the old segment later, without
3484 even knowing the name and type of the current segment.
3486 The assembler will print an error message if the segment stack is already
3487 full, when this command is issued.
3489 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3492 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3494 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3495 name=".ORG"></tt> command.
3498 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3500 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3501 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3502 a constant expression that tells how many times the commands in the body
3503 should get repeated. Optionally, a comma and an identifier may be specified.
3504 If this identifier is found in the body of the repeat statement, it is
3505 replaced by the current repeat count (starting with zero for the first time
3506 the body is repeated).
3508 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3509 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3510 level will be used, not the one from the outer level.
3514 The following macro will emit a string that is "encrypted" in that all
3515 characters of the string are XORed by the value $55.
3519 .repeat .strlen(Arg), I
3520 .byte .strat(Arg, I) ^ $55
3525 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3528 <sect1><tt>.RES</tt><label id=".RES"><p>
3530 Reserve storage. The command is followed by one or two constant
3531 expressions. The first one is mandatory and defines, how many bytes of
3532 storage should be defined. The second, optional expression must by a
3533 constant byte value that will be used as value of the data. If there
3534 is no fill value given, the linker will use the value defined in the
3535 linker configuration file (default: zero).
3540 ; Reserve 12 bytes of memory with value $AA
3545 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3547 Switch to the RODATA segment. The name of the RODATA segment is always
3548 "RODATA", so this is a shortcut for
3554 The RODATA segment is a segment that is used by the compiler for
3555 readonly data like string constants.
3557 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3560 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3562 Start a nested lexical level with the given name. All new symbols from now
3563 on are in the local lexical level and are accessible from outside only via
3564 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3565 outside this local level may be accessed as long as their names are not used
3566 for new symbols inside the level. Symbols names in other lexical levels do
3567 not clash, so you may use the same names for identifiers. The lexical level
3568 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3569 read. Lexical levels may be nested up to a depth of 16 (this is an
3570 artificial limit to protect against errors in the source).
3572 Note: Macro names are always in the global level and in a separate name
3573 space. There is no special reason for this, it's just that I've never
3574 had any need for local macro definitions.
3579 .scope Error ; Start new scope named Error
3581 File = 1 ; File error
3582 Parse = 2 ; Parse error
3583 .endscope ; Close lexical level
3586 lda #Error::File ; Use symbol from scope Error
3589 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3593 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3595 Switch to another segment. Code and data is always emitted into a
3596 segment, that is, a named section of data. The default segment is
3597 "CODE". There may be up to 254 different segments per object file
3598 (and up to 65534 per executable). There are shortcut commands for
3599 the most common segments ("CODE", "DATA" and "BSS").
3601 The command is followed by a string containing the segment name (there are
3602 some constraints for the name - as a rule of thumb use only those segment
3603 names that would also be valid identifiers). There may also be an optional
3604 address size separated by a colon. See the section covering <tt/<ref
3605 id="address-sizes" name="address sizes">/ for more information.
3607 The default address size for a segment depends on the memory model specified
3608 on the command line. The default is "absolute", which means that you don't
3609 have to use an address size modifier in most cases.
3611 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3612 That is, the segment will reside somewhere in core memory outside the zero
3613 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3614 page and direct (short) addressing is possible for data in this segment.
3616 Beware: Only labels in a segment with the zeropage attribute are marked
3617 as reachable by short addressing. The `*' (PC counter) operator will
3618 work as in other segments and will create absolute variable values.
3620 Please note that a segment cannot have two different address sizes. A
3621 segment specified as zeropage cannot be declared as being absolute later.
3626 .segment "ROM2" ; Switch to ROM2 segment
3627 .segment "ZP2": zeropage ; New direct segment
3628 .segment "ZP2" ; Ok, will use last attribute
3629 .segment "ZP2": absolute ; Error, redecl mismatch
3632 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3633 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3634 id=".RODATA" name=".RODATA"></tt>
3637 <sect1><tt>.SET</tt><label id=".SET"><p>
3639 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3640 name="Numeric variables"> for a full description.
3643 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3645 Switch the CPU instruction set. The command is followed by a string that
3646 specifies the CPU. Possible values are those that can also be supplied to
3647 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3648 namely: 6502, 6502X, 65SC02, 65C02, 65816 and HuC6280.
3650 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3651 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3652 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3653 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3654 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3655 <tt><ref id=".P02" name=".P02"></tt>,
3656 <tt><ref id=".P816" name=".P816"></tt>,
3657 <tt><ref id=".PC02" name=".PC02"></tt>,
3658 <tt><ref id=".PSC02" name=".PSC02"></tt>
3661 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3663 Switch on or off smart mode. The command must be followed by a '+' or '-'
3664 character to switch the option on or off respectively. The default is off
3665 (that is, the assembler doesn't try to be smart), but this default may be
3666 changed by the -s switch on the command line.
3668 In smart mode the assembler will do the following:
3671 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3672 and update the operand sizes accordingly. If the operand of such an
3673 instruction cannot be evaluated by the assembler (for example, because
3674 the operand is an imported symbol), a warning is issued. Beware: Since
3675 the assembler cannot trace the execution flow this may lead to false
3676 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3677 instructions to tell the assembler about the current settings.
3678 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3679 used within a procedure declared as <tt/far/, or if the procedure has
3680 no explicit address specification, but it is <tt/far/ because of the
3688 .smart - ; Stop being smart
3691 See: <tt><ref id=".A16" name=".A16"></tt>,
3692 <tt><ref id=".A8" name=".A8"></tt>,
3693 <tt><ref id=".I16" name=".I16"></tt>,
3694 <tt><ref id=".I8" name=".I8"></tt>
3697 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3699 Starts a struct definition. Structs are covered in a separate section named
3700 <ref id="structs" name=""Structs and unions"">.
3702 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3703 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3704 <tt><ref id=".UNION" name=".UNION"></tt>
3707 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3709 Allocate space for a struct or union.
3720 .tag Point ; Allocate 4 bytes
3724 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3726 Delete a define style macro definition. The command is followed by an
3727 identifier which specifies the name of the macro to delete. Macro
3728 replacement is switched of when reading the token following the command
3729 (otherwise the macro name would be replaced by its replacement list).
3731 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3732 section <ref id="macros" name="Macros">.
3735 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3737 Starts a union definition. Unions are covered in a separate section named
3738 <ref id="structs" name=""Structs and unions"">.
3740 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3741 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3742 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3745 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3747 Force an assembly warning. The assembler will output a warning message
3748 preceded by "User warning". This warning will always be output, even if
3749 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3750 command line option.
3752 This command may be used to output possible problems when assembling
3761 .warning "Forward jump in jne, cannot optimize!"
3771 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3772 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3773 <tt><ref id=".OUT" name=".OUT"></tt>
3776 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3778 Define word sized data. Must be followed by a sequence of (word ranged,
3779 but not necessarily constant) expressions.
3784 .word $0D00, $AF13, _Clear
3788 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3790 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3791 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3795 .segment "ZEROPAGE", zeropage
3798 Because of the "zeropage" attribute, labels declared in this segment are
3799 addressed using direct addressing mode if possible. You <em/must/ instruct
3800 the linker to place this segment somewhere in the address range 0..$FF
3801 otherwise you will get errors.
3803 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3807 <sect>Macros<label id="macros"><p>
3810 <sect1>Introduction<p>
3812 Macros may be thought of as "parametrized super instructions". Macros are
3813 sequences of tokens that have a name. If that name is used in the source
3814 file, the macro is "expanded", that is, it is replaced by the tokens that
3815 were specified when the macro was defined.
3818 <sect1>Macros without parameters<p>
3820 In its simplest form, a macro does not have parameters. Here's an
3824 .macro asr ; Arithmetic shift right
3825 cmp #$80 ; Put bit 7 into carry
3826 ror ; Rotate right with carry
3830 The macro above consists of two real instructions, that are inserted into
3831 the code, whenever the macro is expanded. Macro expansion is simply done
3832 by using the name, like this:
3841 <sect1>Parametrized macros<p>
3843 When using macro parameters, macros can be even more useful:
3857 When calling the macro, you may give a parameter, and each occurrence of
3858 the name "addr" in the macro definition will be replaced by the given
3877 A macro may have more than one parameter, in this case, the parameters
3878 are separated by commas. You are free to give less parameters than the
3879 macro actually takes in the definition. You may also leave intermediate
3880 parameters empty. Empty parameters are replaced by empty space (that is,
3881 they are removed when the macro is expanded). If you have a look at our
3882 macro definition above, you will see, that replacing the "addr" parameter
3883 by nothing will lead to wrong code in most lines. To help you, writing
3884 macros with a variable parameter list, there are some control commands:
3886 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3887 returns true, if there are any tokens on the remainder of the line. Since
3888 empty parameters are replaced by nothing, this may be used to test if a given
3889 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3892 Look at this example:
3895 .macro ldaxy a, x, y
3908 This macro may be called as follows:
3911 ldaxy 1, 2, 3 ; Load all three registers
3913 ldaxy 1, , 3 ; Load only a and y
3915 ldaxy , , 3 ; Load y only
3918 There's another helper command for determining, which macro parameters are
3919 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3920 replaced by the parameter count given, <em/including/ intermediate empty macro
3924 ldaxy 1 ; .PARAMCOUNT = 1
3925 ldaxy 1,,3 ; .PARAMCOUNT = 3
3926 ldaxy 1,2 ; .PARAMCOUNT = 2
3927 ldaxy 1, ; .PARAMCOUNT = 2
3928 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3931 Macro parameters may optionally be enclosed into curly braces. This allows the
3932 inclusion of tokens that would otherwise terminate the parameter (the comma in
3933 case of a macro parameter).
3936 .macro foo arg1, arg2
3940 foo ($00,x) ; Two parameters passed
3941 foo {($00,x)} ; One parameter passed
3944 In the first case, the macro is called with two parameters: '<tt/($00/'
3945 and 'x)'. The comma is not passed to the macro, since it is part of the
3946 calling sequence, not the parameters.
3948 In the second case, '($00,x)' is passed to the macro, this time
3949 including the comma.
3952 <sect1>Detecting parameter types<p>
3954 Sometimes it is nice to write a macro that acts differently depending on the
3955 type of the argument supplied. An example would be a macro that loads a 16 bit
3956 value from either an immediate operand, or from memory. The <tt/<ref
3957 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3958 functions will allow you to do exactly this:
3962 .if (.match (.left (1, {arg}), #))
3964 lda #<(.right (.tcount ({arg})-1, {arg}))
3965 ldx #>(.right (.tcount ({arg})-1, {arg}))
3967 ; assume absolute or zero page
3974 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3975 check if its argument begins with a hash mark. If so, two immediate loads are
3976 emitted, Otherwise a load from an absolute zero page memory location is
3977 assumed. Please note how the curly braces are used to enclose parameters to
3978 pseudo functions handling token lists. This is necessary, because the token
3979 lists may include commas or parens, which would be treated by the assembler
3982 The macro can be used as
3987 ldax #$1234 ; X=$12, A=$34
3989 ldax foo ; X=$56, A=$78
3993 <sect1>Recursive macros<p>
3995 Macros may be used recursively:
3998 .macro push r1, r2, r3
4007 There's also a special macro to help writing recursive macros: <tt><ref
4008 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
4012 .macro push r1, r2, r3, r4, r5, r6, r7
4014 ; First parameter is empty
4020 push r2, r3, r4, r5, r6, r7
4024 When expanding this macro, the expansion will push all given parameters
4025 until an empty one is encountered. The macro may be called like this:
4028 push $20, $21, $32 ; Push 3 ZP locations
4029 push $21 ; Push one ZP location
4033 <sect1>Local symbols inside macros<p>
4035 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4036 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4037 Have a look at the inc16 macro above. Here is it again:
4051 If you have a closer look at the code, you will notice, that it could be
4052 written more efficiently, like this:
4063 But imagine what happens, if you use this macro twice? Since the label "Skip"
4064 has the same name both times, you get a "duplicate symbol" error. Without a
4065 way to circumvent this problem, macros are not as useful, as they could be.
4066 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4067 It declares one or more symbols as local to the macro expansion. The names of
4068 local variables are replaced by a unique name in each separate macro
4069 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4073 .local Skip ; Make Skip a local symbol
4077 Skip: ; Not visible outside
4081 Another solution is of course to start a new lexical block inside the macro
4082 that hides any labels:
4096 <sect1>C style macros<p>
4098 Starting with version 2.5 of the assembler, there is a second macro type
4099 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4100 similar to the classic macro type described above, but behaviour is sometimes
4105 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4106 span more than a line. You may use line continuation (see <tt><ref
4107 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4108 more than one line for increased readability, but the macro itself
4109 may not contain an end-of-line token.
4111 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4112 the name space with classic macros, but they are detected and replaced
4113 at the scanner level. While classic macros may be used in every place,
4114 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4115 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4116 they are more versatile in some situations.
4118 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4119 parameters. While classic macros may have empty parameters, this is
4120 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4121 For this macro type, the number of actual parameters must match
4122 exactly the number of formal parameters.
4124 To make this possible, formal parameters are enclosed in braces when
4125 defining the macro. If there are no parameters, the empty braces may
4128 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4129 contain end-of-line tokens, there are things that cannot be done. They
4130 may not contain several processor instructions for example. So, while
4131 some things may be done with both macro types, each type has special
4132 usages. The types complement each other.
4136 Let's look at a few examples to make the advantages and disadvantages
4139 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4140 following <tt/.DEFINE/:
4145 foo EQU $1234 ; This is accepted now
4148 You may use the directive to define string constants used elsewhere:
4151 ; Define the version number
4152 .define VERSION "12.3a"
4158 Macros with parameters may also be useful:
4161 .define DEBUG(message) .out message
4163 DEBUG "Assembling include file #3"
4166 Note that, while formal parameters have to be placed in braces, this is
4167 not true for the actual parameters. Beware: Since the assembler cannot
4168 detect the end of one parameter, only the first token is used. If you
4169 don't like that, use classic macros instead:
4172 .macro DEBUG message
4177 (This is an example where a problem can be solved with both macro types).
4180 <sect1>Characters in macros<p>
4182 When using the <ref id="option-t" name="-t"> option, characters are translated
4183 into the target character set of the specific machine. However, this happens
4184 as late as possible. This means that strings are translated if they are part
4185 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4186 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4187 used as part of an expression.
4189 This behaviour is very intuitive outside of macros but may be confusing when
4190 doing more complex macros. If you compare characters against numeric values,
4191 be sure to take the translation into account.
4194 <sect1>Deleting macros<p>
4196 Macros can be deleted. This will not work if the macro that should be deleted
4197 is currently expanded as in the following non working example:
4201 .delmacro notworking
4204 notworking ; Will not work
4207 The commands to delete classic and define style macros differ. Classic macros
4208 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4209 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4210 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4218 .byte value ; Emit one byte with value 1
4219 mac ; Emit another byte with value 2
4224 .byte value ; Error: Unknown identifier
4225 mac ; Error: Missing ":"
4228 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4229 the name of such a macro is replaced by its replacement list on a very low
4230 level. To get the actual name, macro replacement has to be switched off when
4231 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4232 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4233 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4234 different commands increases flexibility.
4237 <sect>Macro packages<label id="macropackages"><p>
4239 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4240 macro packages may be included with just one command. Available macro packages
4244 <sect1><tt>.MACPACK generic</tt><p>
4246 This macro package defines macros that are useful in almost any program.
4247 Currently defined macros are:
4291 <sect1><tt>.MACPACK longbranch</tt><p>
4293 This macro package defines long conditional jumps. They are named like the
4294 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4295 definition for the "<tt/jeq/" macro, the other macros are built using the same
4300 .if .def(Target) .and ((*+2)-(Target) <= 127)
4309 All macros expand to a short branch, if the label is already defined (back
4310 jump) and is reachable with a short jump. Otherwise the macro expands to a
4311 conditional branch with the branch condition inverted, followed by an absolute
4312 jump to the actual branch target.
4314 The package defines the following macros:
4317 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4322 <sect1><tt>.MACPACK atari</tt><p>
4324 The atari macro package will define a macro named <tt/scrcode/. It takes a
4325 string as argument and places this string into memory translated into screen
4329 <sect1><tt>.MACPACK cbm</tt><p>
4331 The cbm macro package will define a macro named <tt/scrcode/. It takes a
4332 string as argument and places this string into memory translated into screen
4336 <sect1><tt>.MACPACK cpu</tt><p>
4338 This macro package does not define any macros but constants used to examine
4339 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4340 each supported CPU a constant similar to
4351 is defined. These constants may be used to determine the exact type of the
4352 currently enabled CPU. In addition to that, for each CPU instruction set,
4353 another constant is defined:
4364 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4365 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4366 currently enabled CPU supports a specific instruction set. For example the
4367 65C02 supports all instructions of the 65SC02 CPU, so it has the
4368 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4372 .if (.cpu .bitand CPU_ISET_65SC02)
4380 it is possible to determine if the
4386 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4387 CPUs (the latter two are upwards compatible to the 65SC02).
4391 <sect>Predefined constants<label id="predefined-constants"><p>
4393 For better orthogonality, the assembler defines similar symbols as the
4394 compiler, depending on the target system selected:
4397 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4398 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4399 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4400 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4401 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4402 <item><tt/__BBC__/ - Target system is <tt/bbc/
4403 <item><tt/__C128__/ - Target system is <tt/c128/
4404 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4405 <item><tt/__C64__/ - Target system is <tt/c64/
4406 <item><tt/__CBM__/ - Target is a Commodore system
4407 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4408 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4409 <item><tt/__GEOS__/ - Target is a GEOS system
4410 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4411 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4412 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4413 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4414 <item><tt/__NES__/ - Target system is <tt/nes/
4415 <item><tt/__PET__/ - Target system is <tt/pet/
4416 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4417 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4418 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4419 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4420 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4424 <sect>Structs and unions<label id="structs"><p>
4426 <sect1>Structs and unions Overview<p>
4428 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4429 are to some degree comparable to their C counterparts. Both have a list of
4430 members. Each member allocates storage and may optionally have a name, which,
4431 in case of a struct, is the offset from the beginning and, in case of a union,
4435 <sect1>Declaration<p>
4437 Here is an example for a very simple struct with two members and a total size
4447 A union shares the total space between all its members, its size is the same
4448 as that of the largest member. The offset of all members relative to the union
4458 A struct or union must not necessarily have a name. If it is anonymous, no
4459 local scope is opened, the identifiers used to name the members are placed
4460 into the current scope instead.
4462 A struct may contain unnamed members and definitions of local structs. The
4463 storage allocators may contain a multiplier, as in the example below:
4468 .word 2 ; Allocate two words
4475 <sect1>The <tt/.TAG/ keyword<p>
4477 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4478 for an already defined struct or unions within another struct:
4492 Space for a struct or union may be allocated using the <ref id=".TAG"
4493 name=".TAG"> directive.
4499 Currently, members are just offsets from the start of the struct or union. To
4500 access a field of a struct, the member offset has to be added to the address
4501 of the struct itself:
4504 lda C+Circle::Radius ; Load circle radius into A
4507 This may change in a future version of the assembler.
4510 <sect1>Limitations<p>
4512 Structs and unions are currently implemented as nested symbol tables (in fact,
4513 they were a by-product of the improved scoping rules). Currently, the
4514 assembler has no idea of types. This means that the <ref id=".TAG"
4515 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4516 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4517 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4518 this structure accessible by using the '::' operator.
4522 <sect>Module constructors/destructors<label id="condes"><p>
4524 <em>Note:</em> This section applies mostly to C programs, so the explanation
4525 below uses examples from the C libraries. However, the feature may also be
4526 useful for assembler programs.
4529 <sect1>Module constructors/destructors Overview<p>
4531 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4532 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4533 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4534 special way. The linker is able to generate tables with all functions of a
4535 specific type. Such a table will <em>only</em> include symbols from object
4536 files that are linked into a specific executable. This may be used to add
4537 initialization and cleanup code for library modules, or a table of interrupt
4540 The C heap functions are an example where module initialization code is used.
4541 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4542 variables that contain the start and the end of the heap, pointers to the free
4543 list and so on. Since the end of the heap depends on the size and start of the
4544 stack, it must be initialized at runtime. However, initializing these
4545 variables for programs that do not use the heap are a waste of time and
4548 So the central module defines a function that contains initialization code and
4549 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4550 this module is added to an executable by the linker, the initialization
4551 function will be placed into the table of constructors by the linker. The C
4552 startup code will call all constructors before <tt/main/ and all destructors
4553 after <tt/main/, so without any further work, the heap initialization code is
4554 called once the module is linked in.
4556 While it would be possible to add explicit calls to initialization functions
4557 in the startup code, the new approach has several advantages:
4561 If a module is not included, the initialization code is not linked in and not
4562 called. So you don't pay for things you don't need.
4565 Adding another library that needs initialization does not mean that the
4566 startup code has to be changed. Before we had module constructors and
4567 destructors, the startup code for all systems had to be adjusted to call the
4568 new initialization code.
4571 The feature saves memory: Each additional initialization function needs just
4572 two bytes in the table (a pointer to the function).
4577 <sect1>Calling order<p>
4579 The symbols are sorted in increasing priority order by the linker when using
4580 one of the builtin linker configurations, so the functions with lower
4581 priorities come first and are followed by those with higher priorities. The C
4582 library runtime subroutine that walks over the function tables calls the
4583 functions starting from the top of the table - which means that functions with
4584 a high priority are called first.
4586 So when using the C runtime, functions are called with high priority functions
4587 first, followed by low priority functions.
4592 When using these special symbols, please take care of the following:
4597 The linker will only generate function tables, it will not generate code to
4598 call these functions. If you're using the feature in some other than the
4599 existing C environments, you have to write code to call all functions in a
4600 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4601 in the C runtime for an example on how to do this.
4604 The linker will only add addresses of functions that are in modules linked to
4605 the executable. This means that you have to be careful where to place the
4606 condes functions. If initialization or an irq handler is needed for a group of
4607 functions, be sure to place the function into a module that is linked in
4608 regardless of which function is called by the user.
4611 The linker will generate the tables only when requested to do so by the
4612 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4613 be requested separately.
4616 Constructors and destructors may have priorities. These priorities determine
4617 the order of the functions in the table. If your initialization or cleanup code
4618 does depend on other initialization or cleanup code, you have to choose the
4619 priority for the functions accordingly.
4622 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4623 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4624 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4625 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4626 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4627 (interruptor). The linker generates a separate table for each type on request.
4632 <sect>Porting sources from other assemblers<p>
4634 Sometimes it is necessary to port code written for older assemblers to ca65.
4635 In some cases, this can be done without any changes to the source code by
4636 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4637 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4640 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4641 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4642 done by the linker. Most other assemblers generate absolute code, placement is
4643 done within the assembler and there is no external linker.
4645 In general it is not a good idea to write new code using the emulation
4646 features of the assembler, but there may be situations where even this rule is
4651 You need to use some of the ca65 emulation features to simulate the behaviour
4652 of such simple assemblers.
4655 <item>Prepare your sourcecode like this:
4658 ; if you want TASS style labels without colons
4659 .feature labels_without_colons
4661 ; if you want TASS style character constants
4662 ; ("a" instead of the default 'a')
4663 .feature loose_char_term
4665 .word *+2 ; the cbm load address
4670 notice that the two emulation features are mostly useful for porting
4671 sources originally written in/for TASS, they are not needed for the
4672 actual "simple assembler operation" and are not recommended if you are
4673 writing new code from scratch.
4675 <item>Replace all program counter assignments (which are not possible in ca65
4676 by default, and the respective emulation feature works different from what
4677 you'd expect) by another way to skip to memory locations, for example the
4678 <tt><ref id=".RES" name=".RES"></tt> directive.
4682 .res $2000-* ; reserve memory up to $2000
4685 Please note that other than the original TASS, ca65 can never move the program
4686 counter backwards - think of it as if you are assembling to disk with TASS.
4688 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4689 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4690 of <tt/.goto/, everything involving loops must be replaced by
4691 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4693 <item>To assemble code to a different address than it is executed at, use the
4694 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4695 <tt/.offs/-constructs.
4702 .reloc ; back to normal
4705 <item>Then assemble like this:
4708 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4711 Note that you need to use the actual start address minus two, since two bytes
4712 are used for the cbm load address.
4719 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4720 Bassewitz. For usage of the binaries and/or sources the following
4721 conditions do apply:
4723 This software is provided 'as-is', without any expressed or implied
4724 warranty. In no event will the authors be held liable for any damages
4725 arising from the use of this software.
4727 Permission is granted to anyone to use this software for any purpose,
4728 including commercial applications, and to alter it and redistribute it
4729 freely, subject to the following restrictions:
4732 <item> The origin of this software must not be misrepresented; you must not
4733 claim that you wrote the original software. If you use this software
4734 in a product, an acknowledgment in the product documentation would be
4735 appreciated but is not required.
4736 <item> Altered source versions must be plainly marked as such, and must not
4737 be misrepresented as being the original software.
4738 <item> This notice may not be removed or altered from any source