1 <!doctype linuxdoc system>
4 <title>ca65 Users Guide
5 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
6 <date>2000-07-19, 2000-11-29, 2001-10-02, 2005-09-08
9 ca65 is a powerful macro assembler for the 6502, 65C02 and 65816 CPUs. It is
10 used as a companion assembler for the cc65 crosscompiler, but it may also be
11 used as a standalone product.
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
22 compiler, originally developed by John R. Dunning. I had some problems with
23 ra65 and the copyright does not permit some things which I wanted to be
24 possible, so I decided to write a completely new assembler/linker/archiver
25 suite for the cc65 compiler. ca65 is part of this suite.
27 Some parts of the assembler (code generation and some routines for symbol
28 table handling) are taken from an older crossassembler named a816 written
29 by me a long time ago.
32 <sect1>Design criteria<p>
34 Here's a list of the design criteria, that I considered important for the
39 <item> The assembler must support macros. Macros are not essential, but they
40 make some things easier, especially when you use the assembler in the
41 backend of a compiler.
42 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
43 thinking about a 65816 backend for the C compiler, and even my old
44 a816 assembler had support for these CPUs, so this wasn't really a
46 <item> The assembler must produce relocatable code. This is necessary for the
47 compiler support, and it is more convenient.
48 <item> Conditional assembly must be supported. This is a must for bigger
49 projects written in assembler (like Elite128).
50 <item> The assembler must support segments, and it must support more than
51 three segments (this is the count, most other assemblers support).
52 Having more than one code segments helps developing code for systems
53 with a divided ROM area (like the C64).
54 <item> The linker must be able to resolve arbitrary expressions. It should
55 be able to get things like
62 <item> True lexical nesting for symbols. This is very convenient for larger
64 <item> "Cheap" local symbols without lexical nesting for those quick, late
66 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
67 introduced the concept into the object file format use by the new cc65
69 <item> The assembler will be a one pass assembler. There was no real need for
70 this decision, but I've written several multipass assemblers, and it
71 started to get boring. A one pass assembler needs much more elaborated
72 data structures, and because of that it's much more fun:-)
73 <item> Non-GPLed code that may be used in any project without restrictions or
74 fear of "GPL infecting" other code.
82 <sect1>Command line option overview<p>
84 The assembler accepts the following options:
87 ---------------------------------------------------------------------------
88 Usage: ca65 [options] file
90 -D name[=value] Define a symbol
91 -I dir Set an include directory search path
92 -U Mark unresolved symbols as import
93 -V Print the assembler version
94 -W n Set warning level n
95 -g Add debug info to object file
97 -i Ignore case of symbols
98 -l Create a listing if assembly was ok
99 -mm model Set the memory model
100 -o name Name the output file
102 -t sys Set the target system
103 -v Increase verbosity
106 --auto-import Mark unresolved symbols as import
107 --cpu type Set cpu type
108 --debug-info Add debug info to object file
109 --feature name Set an emulation feature
110 --help Help (this text)
111 --ignore-case Ignore case of symbols
112 --include-dir dir Set an include directory search path
113 --listing Create a listing if assembly was ok
114 --list-bytes n Maximum number of bytes per listing line
115 --macpack-dir dir Set a macro package directory
116 --memory-model model Set the memory model
117 --pagelength n Set the page length for the listing
118 --smart Enable smart mode
119 --target sys Set the target system
120 --verbose Increase verbosity
121 --version Print the assembler version
122 ---------------------------------------------------------------------------
126 <sect1>Command line options in detail<p>
128 Here is a description of all the command line options:
132 <label id="option--cpu">
133 <tag><tt>--cpu type</tt></tag>
135 Set the default for the CPU type. The option takes a parameter, which
138 6502, 65SC02, 65C02, 65816, sunplus, sweet16, HuC6280
140 The sunplus cpu is not available in the freeware version, because the
141 instruction set is "proprietary and confidential".
144 <label id="option--feature">
145 <tag><tt>--feature name</tt></tag>
147 Enable an emulation feature. This is identical as using <tt/.FEATURE/
148 in the source with two exceptions: Feature names must be lower case, and
149 each feature must be specified by using an extra <tt/--feature/ option,
150 comma separated lists are not allowed.
152 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
153 command for a list of emulation features.
156 <label id="option-g">
157 <tag><tt>-g, --debug-info</tt></tag>
159 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
160 used, the assembler will add a section to the object file that contains
161 all symbols (including local ones) together with the symbol values and
162 source file positions. The linker will put these additional symbols into
163 the VICE label file, so even local symbols can be seen in the VICE
167 <tag><tt>-h, --help</tt></tag>
169 Print the short option summary shown above.
172 <tag><tt>-i, --ignore-case</tt></tag>
174 This option makes the assembler case insensitive on identifiers and labels.
175 This option will override the default, but may itself be overridden by the
176 <tt><ref id=".CASE" name=".CASE"></tt> control command.
179 <tag><tt>-l, --listing</tt></tag>
181 Generate an assembler listing. The listing file will always have the
182 name of the main input file with the extension replaced by ".lst". This
183 may change in future versions.
186 <tag><tt>--list-bytes n</tt></tag>
188 Set the maximum number of bytes printed in the listing for one line of
189 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
190 for more information. The value zero can be used to encode an unlimited
191 number of printed bytes.
194 <tag><tt>--macpack-dir dir</tt></tag>
196 This options allows to specify a directory containing macro files that are
197 used instead of the builtin images when a <tt><ref id=".MACPACK"
198 name=".MACPACK"></tt> directive is encountered. If <tt>--macpack-dir</tt>
199 was specified, a <tt>.mac</tt> extension is added to the package name and
200 the resulting file is loaded from the given directory. This is most useful
201 when debugging the builtin macro packages.
204 <tag><tt>-mm model, --memory-model model</tt></tag>
206 Define the default memory model. Possible model specifiers are near, far and
210 <tag><tt>-o name</tt></tag>
212 The default output name is the name of the input file with the extension
213 replaced by ".o". If you don't like that, you may give another name with
214 the -o option. The output file will be placed in the same directory as
215 the source file, or, if -o is given, the full path in this name is used.
218 <tag><tt>--pagelength n</tt></tag>
220 sets the length of a listing page in lines. See the <tt><ref
221 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
224 <tag><tt>-s, --smart-mode</tt></tag>
226 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
227 pseudo instruction) the assembler will track usage of the <tt/REP/ and
228 <tt/SEP/ instructions in 65816 mode and update the operand sizes
229 accordingly. If the operand of such an instruction cannot be evaluated by
230 the assembler (for example, because the operand is an imported symbol), a
233 Beware: Since the assembler cannot trace the execution flow this may
234 lead to false results in some cases. If in doubt, use the .ixx and .axx
235 instructions to tell the assembler about the current settings. Smart
236 mode is off by default.
239 <label id="option-t">
240 <tag><tt>-t sys, --target sys</tt></tag>
242 Set the target system. This will enable translation of character strings
243 and character constants into the character set of the target platform.
244 The default for the target system is "none", which means that no translation
245 will take place. The assembler supports the same target systems as the
246 compiler, see there for a list.
249 <tag><tt>-v, --verbose</tt></tag>
251 Increase the assembler verbosity. Usually only needed for debugging
252 purposes. You may use this option more than one time for even more
256 <tag><tt>-D</tt></tag>
258 This option allows you to define symbols on the command line. Without a
259 value, the symbol is defined with the value zero. When giving a value,
260 you may use the '$' prefix for hexadecimal symbols. Please note
261 that for some operating systems, '$' has a special meaning, so
262 you may have to quote the expression.
265 <tag><tt>-I dir, --include-dir dir</tt></tag>
267 Name a directory which is searched for include files. The option may be
268 used more than once to specify more than one directory to search. The
269 current directory is always searched first before considering any
270 additional directories.
273 <tag><tt>-U, --auto-import</tt></tag>
275 Mark symbols that are not defined in the sources as imported symbols. This
276 should be used with care since it delays error messages about typos and such
277 until the linker is run. The compiler uses the equivalent of this switch
278 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
279 symbols for the runtime library. However, the compiler is supposed to
280 generate code that runs through the assembler without problems, something
281 which is not always true for assembler programmers.
284 <tag><tt>-V, --version</tt></tag>
286 Print the version number of the assembler. If you send any suggestions
287 or bugfixes, please include the version number.
290 <label id="option-W">
291 <tag><tt>-Wn</tt></tag>
293 Set the warning level for the assembler. Using -W2 the assembler will
294 even warn about such things like unused imported symbols. The default
295 warning level is 1, and it would probably be silly to set it to
302 <sect>Input format<p>
304 <sect1>Assembler syntax<p>
306 The assembler accepts the standard 6502/65816 assembler syntax. One line may
307 contain a label (which is identified by a colon), and, in addition to the
308 label, an assembler mnemonic, a macro, or a control command (see section <ref
309 id="control-commands" name="Control Commands"> for supported control
310 commands). Alternatively, the line may contain a symbol definition using
311 the '=' token. Everything after a semicolon is handled as a comment (that is,
314 Here are some examples for valid input lines:
317 Label: ; A label and a comment
318 lda #$20 ; A 6502 instruction plus comment
319 L1: ldx #$20 ; Same with label
320 L2: .byte "Hello world" ; Label plus control command
321 mymac $20 ; Macro expansion
322 MySym = 3*L1 ; Symbol definition
323 MaSym = Label ; Another symbol
326 The assembler accepts
329 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
330 <tt><ref id=".P02" name=".P02"></tt> command was given).
331 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
332 <ref id="6502X-mode" name="6502X mode">.
333 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
334 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
335 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
336 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
337 <item>all valid 65618 mnemonics when in 65816 mode (after the
338 <tt><ref id=".P816" name=".P816"></tt> command was given).
339 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
340 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
346 In 65816 mode several aliases are accepted in addition to the official
350 BGE is an alias for BCS
351 BLT is an alias for BCC
352 CPA is an alias for CMP
353 DEA is an alias for DEC A
354 INA is an alias for INC A
355 SWA is an alias for XBA
356 TAD is an alias for TCD
357 TAS is an alias for TCS
358 TDA is an alias for TDC
359 TSA is an alias for TSC
364 <sect1>6502X mode<label id="6502X-mode"><p>
366 6502X mode is an extension to the normal 6502 mode. In this mode, several
367 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
368 these instructions are illegal, there are no official mnemonics for them. The
369 unofficial ones are taken from <htmlurl
370 url="http://oxyron.net/graham/opcodes02.html"
371 name="http://oxyron.net/graham/opcodes02.html">. Please note that only the
372 ones marked as "stable" are supported. The following table uses information
373 from the mentioned web page, for more information, see there.
376 <item><tt>ALR: A:=(A and #{imm})*2;</tt>
377 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
378 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
379 <item><tt>AXS: X:=A and X-#{imm};</tt>
380 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
381 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
382 <item><tt>LAS: A,X,S:={adr} and S;</tt>
383 <item><tt>LAX: A,X:={adr};</tt>
384 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
385 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
386 <item><tt>SAX: {adr}:=A and X;</tt>
387 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
388 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
393 <sect1>sweet16 mode<label id="sweet16-mode"><p>
395 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
396 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
397 generate code for this pseudo CPU when switched into sweet16 mode. The
398 following is special in sweet16 mode:
402 <item>The '@' character denotes indirect addressing and is no longer available
403 for cheap local labels. If you need cheap local labels, you will have to
404 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
405 name=".LOCALCHAR">/ command.
407 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
408 these identifiers are reserved words.
412 Please note that the assembler does neither supply the interpreter needed for
413 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
414 nor does it call the interpreter. All this must be done by your program. Apple
415 ][ programmers do probably know how to use sweet16 mode.
417 For more information about SWEET 16, see
418 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
419 name="http://www.6502.org/source/interpreters/sweet16.htm">.
422 <sect1>Number format<p>
424 For literal values, the assembler accepts the widely used number formats: A
425 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
426 denotes a binary value, and a bare number is interpreted as a decimal. There
427 are currently no octal values and no floats.
430 <sect1>Conditional assembly<p>
432 Please note that when using the conditional directives (<tt/.IF/ and friends),
433 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
434 that are not assembled. The reason for this behaviour is that the assembler
435 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
436 conversion of the input stream into tokens still takes place. As a consequence
437 conditional assembly directives may <bf/not/ be used to prevent normal text
438 (used as a comment or similar) from being assembled. <p>
444 <sect1>Expression evaluation<p>
446 All expressions are evaluated with (at least) 32 bit precision. An
447 expression may contain constant values and any combination of internal and
448 external symbols. Expressions that cannot be evaluated at assembly time
449 are stored inside the object file for evaluation by the linker.
450 Expressions referencing imported symbols must always be evaluated by the
454 <sect1>Size of an expression result<p>
456 Sometimes, the assembler must know about the size of the value that is the
457 result of an expression. This is usually the case, if a decision has to be
458 made, to generate a zero page or an absolute memory references. In this
459 case, the assembler has to make some assumptions about the result of an
463 <item> If the result of an expression is constant, the actual value is
464 checked to see if it's a byte sized expression or not.
465 <item> If the expression is explicitly casted to a byte sized expression by
466 one of the '>', '<' or '^' operators, it is a byte expression.
467 <item> If this is not the case, and the expression contains a symbol,
468 explicitly declared as zero page symbol (by one of the .importzp or
469 .exportzp instructions), then the whole expression is assumed to be
471 <item> If the expression contains symbols that are not defined, and these
472 symbols are local symbols, the enclosing scopes are searched for a
473 symbol with the same name. If one exists and this symbol is defined,
474 it's attributes are used to determine the result size.
475 <item> In all other cases the expression is assumed to be word sized.
478 Note: If the assembler is not able to evaluate the expression at assembly
479 time, the linker will evaluate it and check for range errors as soon as
483 <sect1>Boolean expressions<p>
485 In the context of a boolean expression, any non zero value is evaluated as
486 true, any other value to false. The result of a boolean expression is 1 if
487 it's true, and zero if it's false. There are boolean operators with extreme
488 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
489 operators are shortcut operators. That is, if the result of the expression is
490 already known, after evaluating the left hand side, the right hand side is
494 <sect1>Constant expressions<p>
496 Sometimes an expression must evaluate to a constant without looking at any
497 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
498 that decides if parts of the code are assembled or not. An expression used in
499 the <tt/.IF/ command cannot reference a symbol defined later, because the
500 decision about the <tt/.IF/ must be made at the point when it is read. If the
501 expression used in such a context contains only constant numerical values,
502 there is no problem. When unresolvable symbols are involved it may get harder
503 for the assembler to determine if the expression is actually constant, and it
504 is even possible to create expressions that aren't recognized as constant.
505 Simplifying the expressions will often help.
507 In cases where the result of the expression is not needed immediately, the
508 assembler will delay evaluation until all input is read, at which point all
509 symbols are known. So using arbitrary complex constant expressions is no
510 problem in most cases.
514 <sect1>Available operators<label id="operators"><p>
518 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
519 | Built-in string functions| 0@
521 | Built-in pseudo-variables| 1@
522 | Built-in pseudo-functions| 1@
523 +| Unary positive| 1@
524 -| Unary negative| 1@
526 .BITNOT| Unary bitwise not| 1@
528 .LOBYTE| Unary low-byte operator| 1@
530 .HIBYTE| Unary high-byte operator| 1@
532 .BANKBYTE| Unary bank-byte operator| 1@
534 *| Multiplication| 2@
536 .MOD| Modulo operator| 2@
538 .BITAND| Bitwise and| 2@
540 .BITXOR| Binary bitwise xor| 2@
542 .SHL| Shift-left operator| 2@
544 .SHR| Shift-right operator| 2@
546 +| Binary addition| 3@
547 -| Binary subtraction| 3@
549 .BITOR| Bitwise or| 3@
551 = | Compare operator (equal)| 4@
552 <>| Compare operator (not equal)| 4@
553 <| Compare operator (less)| 4@
554 >| Compare operator (greater)| 4@
555 <=| Compare operator (less or equal)| 4@
556 >=| Compare operator (greater or equal)| 4@
559 .AND| Boolean and| 5@
560 .XOR| Boolean xor| 5@
562 ||<newline>
566 .NOT| Boolean not| 7@<hline>
568 <caption>Available operators, sorted by precedence
571 To force a specific order of evaluation, parentheses may be used, as usual.
575 <sect>Symbols and labels<p>
577 The assembler allows you to use symbols instead of naked values to make
578 the source more readable. There are a lot of different ways to define and
579 use symbols and labels, giving a lot of flexibility.
582 <sect1>Numeric constants<p>
584 Numeric constants are defined using the equal sign or the label assignment
585 operator. After doing
591 may use the symbol "two" in every place where a number is expected, and it is
592 evaluated to the value 2 in this context. The label assignment operator causes
593 the same, but causes the symbol to be marked as a label, which may cause a
594 different handling in the debugger:
600 The right side can of course be an expression:
607 <sect1>Standard labels<p>
609 A label is defined by writing the name of the label at the start of the line
610 (before any instruction mnemonic, macro or pseudo directive), followed by a
611 colon. This will declare a symbol with the given name and the value of the
612 current program counter.
615 <sect1>Local labels and symbols<p>
617 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
618 create regions of code where the names of labels and symbols are local to this
619 region. They are not known outside of this region and cannot be accessed from
620 there. Such regions may be nested like PROCEDUREs in Pascal.
622 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
623 directive for more information.
626 <sect1>Cheap local labels<p>
628 Cheap local labels are defined like standard labels, but the name of the
629 label must begin with a special symbol (usually '@', but this can be
630 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
633 Cheap local labels are visible only between two non cheap labels. As soon as a
634 standard symbol is encountered (this may also be a local symbol if inside a
635 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
636 cheap local symbol goes out of scope.
638 You may use cheap local labels as an easy way to reuse common label
639 names like "Loop". Here is an example:
642 Clear: lda #$00 ; Global label
644 @Loop: sta Mem,y ; Local label
648 Sub: ... ; New global label
649 bne @Loop ; ERROR: Unknown identifier!
652 <sect1>Unnamed labels<p>
654 If you really want to write messy code, there are also unnamed labels. These
655 labels do not have a name (you guessed that already, didn't you?). A colon is
656 used to mark the absence of the name.
658 Unnamed labels may be accessed by using the colon plus several minus or plus
659 characters as a label designator. Using the '-' characters will create a back
660 reference (use the n'th label backwards), using '+' will create a forward
661 reference (use the n'th label in forward direction). An example will help to
684 As you can see from the example, unnamed labels will make even short
685 sections of code hard to understand, because you have to count labels
686 to find branch targets (this is the reason why I for my part do
687 prefer the "cheap" local labels). Nevertheless, unnamed labels are
688 convenient in some situations, so it's your decision.
691 <sect1>Using macros to define labels and constants<p>
693 While there are drawbacks with this approach, it may be handy in some
694 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
695 possible to define symbols or constants that may be used elsewhere. Since
696 the macro facility works on a very low level, there is no scoping. On the
697 other side, you may also define string constants this way (this is not
698 possible with the other symbol types).
704 .DEFINE version "SOS V2.3"
706 four = two * two ; Ok
709 .PROC ; Start local scope
710 two = 3 ; Will give "2 = 3" - invalid!
715 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
717 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
718 id="option-g" name="-g"> is given on the command line), global, local and
719 cheap local labels are written to the object file and will be available in the
720 symbol file via the linker. Unnamed labels are not written to the object file,
721 because they don't have a name which would allow to access them.
725 <sect>Scopes<label id="scopes"><p>
727 ca65 implements several sorts of scopes for symbols.
729 <sect1>Global scope<p>
731 All (non cheap local) symbols that are declared outside of any nested scopes
735 <sect1>Cheap locals<p>
737 A special scope is the scope for cheap local symbols. It lasts from one non
738 local symbol to the next one, without any provisions made by the programmer.
739 All other scopes differ in usage but use the same concept internally.
742 <sect1>Generic nested scopes<p>
744 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
745 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
746 The scope can have a name, in which case it is accessible from the outside by
747 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
748 have a name, all symbols created within the scope are local to the scope, and
749 aren't accessible from the outside.
751 A nested scope can access symbols from the local or from enclosing scopes by
752 name without using explicit scope names. In some cases there may be
753 ambiguities, for example if there is a reference to a local symbol that is not
754 yet defined, but a symbol with the same name exists in outer scopes:
766 In the example above, the <tt/lda/ instruction will load the value 3 into the
767 accumulator, because <tt/foo/ is redefined in the scope. However:
779 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
780 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
781 absolute mode is used instead. In fact, the assembler will not use absolute
782 mode by default, but it will search through the enclosing scopes for a symbol
783 with the given name. If one is found, the address size of this symbol is used.
784 This may lead to errors:
796 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
797 instruction, it will search for an already defined symbol <tt/foo/. It will
798 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
799 zeropage symbol. So the assembler will use zeropage addressing mode. If
800 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
801 the address in the <tt/lda/ instruction already translated, but since the new
802 value needs absolute addressing mode, this fails, and an error message "Range
805 Of course the most simple solution for the problem is to move the definition
806 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
807 rare cases when this cannot be done. In these cases, you can use one of the
808 address size override operators:
820 This will cause the <tt/lda/ instruction to be translated using absolute
821 addressing mode, which means changing the symbol reference later does not
825 <sect1>Nested procedures<p>
827 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
828 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
829 name, and a it will introduce a symbol with this name in the enclosing scope.
838 is actually the same as
847 This is the reason why a procedure must have a name. If you want a scope
848 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
850 <bf/Note:/ As you can see from the example above, scopes and symbols live in
851 different namespaces. There can be a symbol named <tt/foo/ and a scope named
852 <tt/foo/ without any conflicts (but see the section titled <ref
853 id="scopesearch" name=""Scope search order"">).
856 <sect1>Structs, unions and enums<p>
858 Structs, unions and enums are explained in a <ref id="structs" name="separate
859 section">, I do only cover them here, because if they are declared with a
860 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
861 name=".SCOPE">/. However, when no name is specified, the behaviour is
862 different: In this case, no new scope will be opened, symbols declared within
863 a struct, union, or enum declaration will then be added to the enclosing scope
867 <sect1>Explicit scope specification<label id="scopesyntax"><p>
869 Accessing symbols from other scopes is possible by using an explicit scope
870 specification, provided that the scope where the symbol lives in has a name.
871 The namespace token (<tt/::/) is used to access other scopes:
879 lda foo::bar ; Access foo in scope bar
882 The only way to deny access to a scope from the outside is to declare a scope
883 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
885 A special syntax is used to specify the global scope: If a symbol or scope is
886 preceded by the namespace token, the global scope is searched:
893 lda #::bar ; Access the global bar (which is 3)
898 <sect1>Scope search order<label id="scopesearch"><p>
900 The assembler searches for a scope in a similar way as for a symbol. First, it
901 looks in the current scope, and then it walks up the enclosing scopes until
904 However, one important thing to note when using explicit scope syntax is, that
905 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
906 used without a preceding definition. This means that in the following
915 lda #foo::bar ; Will load 3, not 2!
922 the reference to the scope <tt/foo/ will use the global scope, and not the
923 local one, because the local one is not visible at the point where it is
926 Things get more complex if a complete chain of scopes is specified:
937 lda #outer::inner::bar ; 1
949 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
950 assembler will first search in the local scope for a scope named <tt/outer/.
951 Since none is found, the enclosing scope (<tt/another/) is checked. There is
952 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
953 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
954 this scope, the assembler looks for a symbol named <tt/bar/.
956 Please note that once the anchor scope is found, all following scopes
957 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
958 assembler will search the scope tree only for the first scope (if it is not
959 anchored in the root scope). Starting from there on, there is no flexibility,
960 so if the scope named <tt/outer/ found by the assembler does not contain a
961 scope named <tt/inner/, this would be an error, even if such a pair does exist
962 (one level up in global scope).
964 Ambiguities that may be introduced by this search algorithm may be removed by
965 anchoring the scope specification in the global scope. In the example above,
966 if you want to access the "other" symbol <tt/bar/, you would have to write:
977 lda #::outer::inner::bar ; 2
990 <sect>Address sizes and memory models<label id="address-sizes"><p>
992 <sect1>Address sizes<p>
994 ca65 assigns each segment and each symbol an address size. This is true, even
995 if the symbol is not used as an address. You may also think of a value range
996 of the symbol instead of an address size.
998 Possible address sizes are:
1001 <item>Zeropage or direct (8 bits)
1002 <item>Absolute (16 bits)
1004 <item>Long (32 bits)
1007 Since the assembler uses default address sizes for the segments and symbols,
1008 it is usually not necessary to override the default behaviour. In cases, where
1009 it is necessary, the following keywords may be used to specify address sizes:
1012 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1013 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1014 <item>FAR for far addressing (24 bits).
1015 <item>LONG or DWORD for long addressing (32 bits).
1019 <sect1>Address sizes of segments<p>
1021 The assembler assigns an address size to each segment. Since the
1022 representation of a label within this segment is "segment start + offset",
1023 labels will inherit the address size of the segment they are declared in.
1025 The address size of a segment may be changed, by using an optional address
1026 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1027 an explanation on how this is done.
1030 <sect1>Address sizes of symbols<p>
1035 <sect1>Memory models<p>
1037 The default address size of a segment depends on the memory model used. Since
1038 labels inherit the address size from the segment they are declared in,
1039 changing the memory model is an easy way to change the address size of many
1045 <sect>Pseudo variables<label id="pseudo-variables"><p>
1047 Pseudo variables are readable in all cases, and in some special cases also
1050 <sect1><tt>*</tt><p>
1052 Reading this pseudo variable will return the program counter at the start
1053 of the current input line.
1055 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1056 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1057 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1060 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1062 Reading this pseudo variable will give a constant integer value that
1063 tells which CPU is currently enabled. It can also tell which instruction
1064 set the CPU is able to translate. The value read from the pseudo variable
1065 should be further examined by using one of the constants defined by the
1066 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1068 It may be used to replace the .IFPxx pseudo instructions or to construct
1069 even more complex expressions.
1075 .if (.cpu .bitand CPU_ISET_65816)
1087 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1089 This builtin pseudo variable is only available in macros. It is replaced by
1090 the actual number of parameters that were given in the macro invocation.
1095 .macro foo arg1, arg2, arg3
1096 .if .paramcount <> 3
1097 .error "Too few parameters for macro foo"
1103 See section <ref id="macros" name="Macros">.
1106 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1108 Reading this pseudo variable will give a constant integer value that
1109 represents the current time in POSIX standard (as seconds since the
1112 It may be used to encode the time of translation somewhere in the created
1118 .dword .time ; Place time here
1122 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1124 Reading this pseudo variable will give the assembler version according to
1125 the following formula:
1127 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1129 It may be used to encode the assembler version or check the assembler for
1130 special features not available with older versions.
1134 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1135 reading the pseudo variable <tt/.VERSION/.
1139 <sect>Pseudo functions<label id="pseudo-functions"><p>
1141 Pseudo functions expect their arguments in parenthesis, and they have a result,
1142 either a string or an expression.
1145 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1147 The function returns the bank byte (that is, bits 16-23) of its argument.
1148 It works identical to the '^' operator.
1150 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1151 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1154 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1156 Builtin function. The function evaluates its argument in braces and yields
1157 "false" if the argument is non blank (there is an argument), and "true" if
1158 there is no argument. The token list that makes up the function argument
1159 may optionally be enclosed in curly braces. This allows the inclusion of
1160 tokens that would otherwise terminate the list (the closing right
1161 parenthesis). The curly braces are not considered part of the list, a list
1162 just consisting of curly braces is considered to be empty.
1164 As an example, the <tt/.IFBLANK/ statement may be replaced by
1172 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1174 Builtin string function. The function allows to concatenate a list of string
1175 constants separated by commas. The result is a string constant that is the
1176 concatenation of all arguments. This function is most useful in macros and
1177 when used together with the <tt/.STRING/ builtin function. The function may
1178 be used in any case where a string constant is expected.
1183 .include .concat ("myheader", ".", "inc")
1186 This is the same as the command
1189 .include "myheader.inc"
1193 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1195 Builtin function. The function evaluates its argument in braces and
1196 yields "true" if the argument is a constant expression (that is, an
1197 expression that yields a constant value at assembly time) and "false"
1198 otherwise. As an example, the .IFCONST statement may be replaced by
1205 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1207 The function returns the high byte (that is, bits 8-15) of its argument.
1208 It works identical to the '>' operator.
1210 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1211 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1214 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1216 The function returns the high word (that is, bits 16-31) of its argument.
1218 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1221 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1223 The function expects a string as its argument, and converts this argument
1224 into an identifier. If the string starts with the current <tt/<ref
1225 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1226 identifier, otherwise it will be converted into a normal identifier.
1231 .macro makelabel arg1, arg2
1232 .ident (.concat (arg1, arg2)):
1235 makelabel "foo", "bar"
1237 .word foobar ; Valid label
1241 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1243 Builtin function. Extracts the left part of a given token list.
1248 .LEFT (<int expr>, <token list>)
1251 The first integer expression gives the number of tokens to extract from
1252 the token list. The second argument is the token list itself. The token
1253 list may optionally be enclosed into curly braces. This allows the
1254 inclusion of tokens that would otherwise terminate the list (the closing
1255 right paren in the given case).
1259 To check in a macro if the given argument has a '#' as first token
1260 (immediate addressing mode), use something like this:
1265 .if (.match (.left (1, {arg}), #))
1267 ; ldax called with immediate operand
1275 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1276 name=".RIGHT"></tt> builtin functions.
1279 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1281 The function returns the low byte (that is, bits 0-7) of its argument.
1282 It works identical to the '<' operator.
1284 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1285 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1288 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1290 The function returns the low word (that is, bits 0-15) of its argument.
1292 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1295 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1297 Builtin function. Matches two token lists against each other. This is
1298 most useful within macros, since macros are not stored as strings, but
1304 .MATCH(<token list #1>, <token list #2>)
1307 Both token list may contain arbitrary tokens with the exception of the
1308 terminator token (comma resp. right parenthesis) and
1315 The token lists may optionally be enclosed into curly braces. This allows
1316 the inclusion of tokens that would otherwise terminate the list (the closing
1317 right paren in the given case). Often a macro parameter is used for any of
1320 Please note that the function does only compare tokens, not token
1321 attributes. So any number is equal to any other number, regardless of the
1322 actual value. The same is true for strings. If you need to compare tokens
1323 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1324 name=".XMATCH"></tt> function.
1328 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1329 while honoring the sign bit. The builtin processor instructions will allow
1330 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1331 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1332 to check for this and print and error for invalid calls.
1337 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1338 .error "Syntax error"
1341 cmp #$80 ; Bit 7 into carry
1342 lsr a ; Shift carry into bit 7
1347 The macro will only accept no arguments, or one argument that must be the
1348 reserved keyword "A".
1350 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1353 <sect1><tt>.MID</tt><label id=".MID"><p>
1355 Builtin function. Takes a starting index, a count and a token list as
1356 arguments. Will return part of the token list.
1361 .MID (<int expr>, <int expr>, <token list>)
1364 The first integer expression gives the starting token in the list (the first
1365 token has index 0). The second integer expression gives the number of tokens
1366 to extract from the token list. The third argument is the token list itself.
1367 The token list may optionally be enclosed into curly braces. This allows the
1368 inclusion of tokens that would otherwise terminate the list (the closing
1369 right paren in the given case).
1373 To check in a macro if the given argument has a '<tt/#/' as first token
1374 (immediate addressing mode), use something like this:
1379 .if (.match (.mid (0, 1, {arg}), #))
1381 ; ldax called with immediate operand
1389 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1390 name=".RIGHT"></tt> builtin functions.
1393 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1395 Builtin function. The function expects an identifier as argument in braces.
1396 The argument is evaluated, and the function yields "true" if the identifier
1397 is a symbol that has already been referenced somewhere in the source file up
1398 to the current position. Otherwise the function yields false. As an example,
1399 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1405 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1408 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1410 Builtin function. Extracts the right part of a given token list.
1415 .RIGHT (<int expr>, <token list>)
1418 The first integer expression gives the number of tokens to extract from the
1419 token list. The second argument is the token list itself. The token list
1420 may optionally be enclosed into curly braces. This allows the inclusion of
1421 tokens that would otherwise terminate the list (the closing right paren in
1424 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1425 name=".MID"></tt> builtin functions.
1428 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1430 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1431 argument can be a struct/union, a struct member, a procedure, or a label. In
1432 case of a procedure or label, its size is defined by the amount of data
1433 placed in the segment where the label is relative to. If a line of code
1434 switches segments (for example in a macro) data placed in other segments
1435 does not count for the size.
1437 Please note that a symbol or scope must exist, before it is used together with
1438 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1439 A scope has preference over a symbol with the same name, so if the last part
1440 of a name represents both, a scope and a symbol, the scope is chosen over the
1443 After the following code:
1446 .struct Point ; Struct size = 4
1451 P: .tag Point ; Declare a point
1452 @P: .tag Point ; Declare another point
1464 .data ; Segment switch!!!
1470 <tag><tt/.sizeof(Point)/</tag>
1471 will have the value 4, because this is the size of struct <tt/Point/.
1473 <tag><tt/.sizeof(Point::xcoord)/</tag>
1474 will have the value 2, because this is the size of the member <tt/xcoord/
1475 in struct <tt/Point/.
1477 <tag><tt/.sizeof(P)/</tag>
1478 will have the value 4, this is the size of the data declared on the same
1479 source line as the label <tt/P/, which is in the same segment that <tt/P/
1482 <tag><tt/.sizeof(@P)/</tag>
1483 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1484 does also work for cheap local symbols.
1486 <tag><tt/.sizeof(Code)/</tag>
1487 will have the value 3, since this is amount of data emitted into the code
1488 segment, the segment that was active when <tt/Code/ was entered. Note that
1489 this value includes the amount of data emitted in child scopes (in this
1490 case <tt/Code::Inner/).
1492 <tag><tt/.sizeof(Code::Inner)/</tag>
1493 will have the value 1 as expected.
1495 <tag><tt/.sizeof(Data)/</tag>
1496 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1497 the segment is switched after entry, this data is emitted into another
1502 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1504 Builtin function. The function accepts a string and an index as
1505 arguments and returns the value of the character at the given position
1506 as an integer value. The index is zero based.
1512 ; Check if the argument string starts with '#'
1513 .if (.strat (Arg, 0) = '#')
1520 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1522 Builtin function. It expects a format string as first argument. The number
1523 and type of the following arguments depend on the format string. The format
1524 string is similar to the one of the C <tt/printf/ function. Missing things
1525 are: Length modifiers, variable width.
1527 The result of the function is a string.
1534 ; Generate an identifier:
1535 .ident (.sprintf ("%s%03d", "label", num)):
1539 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1541 Builtin function. The function accepts an argument in braces and converts
1542 this argument into a string constant. The argument may be an identifier, or
1543 a constant numeric value.
1545 Since you can use a string in the first place, the use of the function may
1546 not be obvious. However, it is useful in macros, or more complex setups.
1551 ; Emulate other assemblers:
1553 .segment .string(name)
1558 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1560 Builtin function. The function accepts a string argument in braces and
1561 evaluates to the length of the string.
1565 The following macro encodes a string as a pascal style string with
1566 a leading length byte.
1570 .byte .strlen(Arg), Arg
1575 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1577 Builtin function. The function accepts a token list in braces. The function
1578 result is the number of tokens given as argument. The token list may
1579 optionally be enclosed into curly braces which are not considered part of
1580 the list and not counted. Enclosement in curly braces allows the inclusion
1581 of tokens that would otherwise terminate the list (the closing right paren
1586 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1587 with the normal 6502 instructions). To translate it into two separate 8 bit
1588 load instructions, the '#' token has to get stripped from the argument:
1592 .if (.match (.mid (0, 1, {arg}), #))
1593 ; ldax called with immediate operand
1594 lda #<(.right (.tcount ({arg})-1, {arg}))
1595 ldx #>(.right (.tcount ({arg})-1, {arg}))
1603 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1605 Builtin function. Matches two token lists against each other. This is
1606 most useful within macros, since macros are not stored as strings, but
1612 .XMATCH(<token list #1>, <token list #2>)
1615 Both token list may contain arbitrary tokens with the exception of the
1616 terminator token (comma resp. right parenthesis) and
1623 The token lists may optionally be enclosed into curly braces. This allows
1624 the inclusion of tokens that would otherwise terminate the list (the closing
1625 right paren in the given case). Often a macro parameter is used for any of
1628 The function compares tokens <em/and/ token values. If you need a function
1629 that just compares the type of tokens, have a look at the <tt><ref
1630 id=".MATCH" name=".MATCH"></tt> function.
1632 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1636 <sect>Control commands<label id="control-commands"><p>
1638 Here's a list of all control commands and a description, what they do:
1641 <sect1><tt>.A16</tt><label id=".A16"><p>
1643 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1645 Note: This command will not emit any code, it will tell the assembler to
1646 create 16 bit operands for immediate accumulator addressing mode.
1648 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1651 <sect1><tt>.A8</tt><label id=".A8"><p>
1653 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1655 Note: This command will not emit any code, it will tell the assembler to
1656 create 8 bit operands for immediate accu addressing mode.
1658 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1661 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1663 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1664 may be used for better readability if the data words are address values. In
1665 65816 mode, the address is forced to be 16 bit wide to fit into the current
1666 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1667 must be followed by a sequence of (not necessarily constant) expressions.
1672 .addr $0D00, $AF13, _Clear
1675 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1679 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1681 Align data to a given boundary. The command expects a constant integer
1682 argument that must be a power of two, plus an optional second argument
1683 in byte range. If there is a second argument, it is used as fill value,
1684 otherwise the value defined in the linker configuration file is used
1685 (the default for this value is zero).
1687 Since alignment depends on the base address of the module, you must
1688 give the same (or a greater) alignment for the segment when linking.
1689 The linker will give you a warning, if you don't do that.
1698 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1700 Define a string with a trailing zero.
1705 Msg: .asciiz "Hello world"
1708 This will put the string "Hello world" followed by a binary zero into
1709 the current segment. There may be more strings separated by commas, but
1710 the binary zero is only appended once (after the last one).
1713 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1715 Add an assertion. The command is followed by an expression, an action
1716 specifier, and an optional message that is output in case the assertion
1717 fails. If no message was given, the string "Assertion failed" is used. The
1718 action specifier may be one of <tt/warning/ or <tt/error/. The assertion is
1719 evaluated by the assembler if possible, and also passed to the linker in the
1720 object file (if one is generated). The linker will then evaluate the
1721 expression when segment placement has been done.
1726 .assert * = $8000, error, "Code not at $8000"
1729 The example assertion will check that the current location is at $8000,
1730 when the output file is written, and abort with an error if this is not
1731 the case. More complex expressions are possible. The action specifier
1732 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1733 an error message. In the latter case, generation if the output file is
1734 suppressed in both the assembler and linker.
1737 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1739 Is followed by a plus or a minus character. When switched on (using a
1740 +), undefined symbols are automatically marked as import instead of
1741 giving errors. When switched off (which is the default so this does not
1742 make much sense), this does not happen and an error message is
1743 displayed. The state of the autoimport flag is evaluated when the
1744 complete source was translated, before outputting actual code, so it is
1745 <em/not/ possible to switch this feature on or off for separate sections
1746 of code. The last setting is used for all symbols.
1748 You should probably not use this switch because it delays error
1749 messages about undefined symbols until the link stage. The cc65
1750 compiler (which is supposed to produce correct assembler code in all
1751 circumstances, something which is not true for most assembler
1752 programmers) will insert this command to avoid importing each and every
1753 routine from the runtime library.
1758 .autoimport + ; Switch on auto import
1762 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1764 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1765 so this is a shortcut for
1771 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1774 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1776 Define byte sized data. Must be followed by a sequence of (byte ranged)
1777 expressions or strings.
1783 .byt "world", $0D, $00
1787 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1789 Switch on or off case sensitivity on identifiers. The default is off
1790 (that is, identifiers are case sensitive), but may be changed by the
1791 -i switch on the command line.
1792 The command must be followed by a '+' or '-' character to switch the
1793 option on or off respectively.
1798 .case - ; Identifiers are not case sensitive
1802 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1804 Apply a custom mapping for characters. The command is followed by two
1805 numbers in the range 1..255. The first one is the index of the source
1806 character, the second one is the mapping. The mapping applies to all
1807 character and string constants when they generate output, and overrides
1808 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1809 command line switch.
1814 .charmap $41, $61 ; Map 'A' to 'a'
1818 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1820 Switch to the CODE segment. The name of the CODE segment is always
1821 "CODE", so this is a shortcut for
1827 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1830 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1832 Export a symbol and mark it in a special way. The linker is able to build
1833 tables of all such symbols. This may be used to automatically create a list
1834 of functions needed to initialize linked library modules.
1836 Note: The linker has a feature to build a table of marked routines, but it
1837 is your code that must call these routines, so just declaring a symbol with
1838 <tt/.CONDES/ does nothing by itself.
1840 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1841 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1842 is implied by <tt/.CONDES/.
1844 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1845 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1846 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1847 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1848 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1849 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
1850 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
1852 After the type, an optional priority may be specified. Higher numeric values
1853 mean higher priority. If no priority is given, the default priority of 7 is
1854 used. Be careful when assigning priorities to your own module constructors
1855 so they won't interfere with the ones in the cc65 library.
1860 .condes ModuleInit, constructor
1861 .condes ModInit, 0, 16
1864 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1865 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1866 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
1867 name="Module constructors/destructors"> explaining the feature in more
1871 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1873 Export a symbol and mark it as a module constructor. This may be used
1874 together with the linker to build a table of constructor subroutines that
1875 are called by the startup code.
1877 Note: The linker has a feature to build a table of marked routines, but it
1878 is your code that must call these routines, so just declaring a symbol as
1879 constructor does nothing by itself.
1881 A constructor is always exported as an absolute (16 bit) symbol. You don't
1882 need to use an additional <tt/.export/ statement, this is implied by
1883 <tt/.constructor/. It may have an optional priority that is separated by a
1884 comma. Higher numeric values mean a higher priority. If no priority is
1885 given, the default priority of 7 is used. Be careful when assigning
1886 priorities to your own module constructors so they won't interfere with the
1887 ones in the cc65 library.
1892 .constructor ModuleInit
1893 .constructor ModInit, 16
1896 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1897 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1898 <ref id="condes" name="Module constructors/destructors"> explaining the
1899 feature in more detail.
1902 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1904 Switch to the DATA segment. The name of the DATA segment is always
1905 "DATA", so this is a shortcut for
1911 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1914 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1916 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1917 create word sized data in native 65XX format). Must be followed by a
1918 sequence of (word ranged) expressions.
1926 This will emit the bytes
1932 into the current segment in that order.
1935 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1937 Switch on or off debug info generation. The default is off (that is,
1938 the object file will not contain debug infos), but may be changed by the
1939 -g switch on the command line.
1940 The command must be followed by a '+' or '-' character to switch the
1941 option on or off respectively.
1946 .debuginfo + ; Generate debug info
1950 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
1952 Start a define style macro definition. The command is followed by an
1953 identifier (the macro name) and optionally by a list of formal arguments
1955 See section <ref id="macros" name="Macros">.
1958 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
1960 Builtin function. The function expects an identifier as argument in braces.
1961 The argument is evaluated, and the function yields "true" if the identifier
1962 is a symbol that is already defined somewhere in the source file up to the
1963 current position. Otherwise the function yields false. As an example, the
1964 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
1971 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
1973 Export a symbol and mark it as a module destructor. This may be used
1974 together with the linker to build a table of destructor subroutines that
1975 are called by the startup code.
1977 Note: The linker has a feature to build a table of marked routines, but it
1978 is your code that must call these routines, so just declaring a symbol as
1979 constructor does nothing by itself.
1981 A destructor is always exported as an absolute (16 bit) symbol. You don't
1982 need to use an additional <tt/.export/ statement, this is implied by
1983 <tt/.destructor/. It may have an optional priority that is separated by a
1984 comma. Higher numerical values mean a higher priority. If no priority is
1985 given, the default priority of 7 is used. Be careful when assigning
1986 priorities to your own module destructors so they won't interfere with the
1987 ones in the cc65 library.
1992 .destructor ModuleDone
1993 .destructor ModDone, 16
1996 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1997 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
1998 section <ref id="condes" name="Module constructors/destructors"> explaining
1999 the feature in more detail.
2002 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2004 Define dword sized data (4 bytes) Must be followed by a sequence of
2010 .dword $12344512, $12FA489
2014 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2016 Conditional assembly: Reverse the current condition.
2019 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2021 Conditional assembly: Reverse current condition and test a new one.
2024 <sect1><tt>.END</tt><label id=".END"><p>
2026 Forced end of assembly. Assembly stops at this point, even if the command
2027 is read from an include file.
2030 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2032 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2035 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2037 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2038 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2041 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2043 End of macro definition (see section <ref id="macros" name="Macros">).
2046 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2048 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2051 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2053 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2056 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2058 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2061 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2063 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2064 command and the separate section named <ref id="structs" name=""Structs
2068 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2070 Start an enumeration. This directive is very similar to the C <tt/enum/
2071 keyword. If a name is given, a new scope is created for the enumeration,
2072 otherwise the enumeration members are placed in the enclosing scope.
2074 In the enumeration body, symbols are declared. The first symbol has a value
2075 of zero, and each following symbol will get the value of the preceding plus
2076 one. This behaviour may be overridden by an explicit assignment. Two symbols
2077 may have the same value.
2089 Above example will create a new scope named <tt/errorcodes/ with three
2090 symbols in it that get the values 0, 1 and 2 respectively. Another way
2091 to write this would have been:
2101 Please note that explicit scoping must be used to access the identifiers:
2104 .word errorcodes::no_error
2107 A more complex example:
2116 EWOULDBLOCK = EAGAIN
2120 In this example, the enumeration does not have a name, which means that the
2121 members will be visible in the enclosing scope and can be used in this scope
2122 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2123 The value for the following members is incremented by one, so <tt/EOK/ would
2124 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2125 override for the value using an already defined symbol.
2128 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2130 Force an assembly error. The assembler will output an error message
2131 preceded by "User error" and will <em/not/ produce an object file.
2133 This command may be used to check for initial conditions that must be
2134 set before assembling a source file.
2144 .error "Must define foo or bar!"
2148 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2149 id=".OUT" name=".OUT"></tt> directives.
2152 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2154 Abort a macro expansion immediately. This command is often useful in
2155 recursive macros. See separate section <ref id="macros" name="Macros">.
2158 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2160 Make symbols accessible from other modules. Must be followed by a comma
2161 separated list of symbols to export, with each one optionally followed by
2162 an address specification. The default is to export the symbol with the
2163 address size it actually has. The assembler will issue a warning, if the
2164 symbol is exported with an address size smaller than the actual address
2174 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2177 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2179 Make symbols accessible from other modules. Must be followed by a comma
2180 separated list of symbols to export. The exported symbols are explicitly
2181 marked as zero page symbols.
2189 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2192 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2194 Define far (24 bit) address data. The command must be followed by a
2195 sequence of (not necessarily constant) expressions.
2200 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2203 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2206 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2208 This directive may be used to enable one or more compatibility features
2209 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2210 possible, it may be useful when porting sources written for other
2211 assemblers. There is no way to switch a feature off, once you have
2212 enabled it, so using
2218 will enable the feature until end of assembly is reached.
2220 The following features are available:
2224 <tag><tt>at_in_identifiers</tt></tag>
2226 Accept the at character (`@') as a valid character in identifiers. The
2227 at character is not allowed to start an identifier, even with this
2230 <tag><tt>dollar_in_identifiers</tt></tag>
2232 Accept the dollar sign (`$') as a valid character in identifiers. The
2233 at character is not allowed to start an identifier, even with this
2236 <tag><tt>dollar_is_pc</tt></tag>
2238 The dollar sign may be used as an alias for the star (`*'), which
2239 gives the value of the current PC in expressions.
2240 Note: Assignment to the pseudo variable is not allowed.
2242 <tag><tt>labels_without_colons</tt></tag>
2244 Allow labels without a trailing colon. These labels are only accepted,
2245 if they start at the beginning of a line (no leading white space).
2247 <tag><tt>leading_dot_in_identifiers</tt></tag>
2249 Accept the dot (`.') as the first character of an identifier. This may be
2250 used for example to create macro names that start with a dot emulating
2251 control directives of other assemblers. Note however, that none of the
2252 reserved keywords built into the assembler, that starts with a dot, may be
2253 overridden. When using this feature, you may also get into trouble if
2254 later versions of the assembler define new keywords starting with a dot.
2256 <tag><tt>loose_char_term</tt></tag>
2258 Accept single quotes as well as double quotes as terminators for char
2261 <tag><tt>loose_string_term</tt></tag>
2263 Accept single quotes as well as double quotes as terminators for string
2266 <tag><tt>missing_char_term</tt></tag>
2268 Accept single quoted character constants where the terminating quote is
2273 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2274 loose_string_term/, since in this case the input would be ambiguous.
2276 <tag><tt>pc_assignment</tt></tag>
2278 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2279 is enabled). Such an assignment is handled identical to the <tt><ref
2280 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2281 removing the lines with the assignments may also be an option when porting
2282 code written for older assemblers).
2284 <tag><tt>ubiquitous_idents</tt></tag>
2286 Allow the use of instructions names as names for macros and symbols. This
2287 makes it possible to "overload" instructions by defining a macro with the
2288 same name. This does also make it possible to introduce hard to find errors
2289 in your code, so be careful!
2293 It is also possible to specify features on the command line using the
2294 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2295 This is useful when translating sources written for older assemblers, when
2296 you don't want to change the source code.
2298 As an example, to translate sources written for Andre Fachats xa65
2299 assembler, the features
2302 labels_without_colons, pc_assignment, loose_char_term
2305 may be helpful. They do not make ca65 completely compatible, so you may not
2306 be able to translate the sources without changes, even when enabling these
2307 features. However, I have found several sources that translate without
2308 problems when enabling these features on the command line.
2311 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2313 Insert an option string into the object file. There are two forms of
2314 this command, one specifies the option by a keyword, the second
2315 specifies it as a number. Since usage of the second one needs knowledge
2316 of the internal encoding, its use is not recommended and I will only
2317 describe the first form here.
2319 The command is followed by one of the keywords
2327 a comma and a string. The option is written into the object file
2328 together with the string value. This is currently unidirectional and
2329 there is no way to actually use these options once they are in the
2335 .fileopt comment, "Code stolen from my brother"
2336 .fileopt compiler, "BASIC 2.0"
2337 .fopt author, "J. R. User"
2341 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2343 Import an absolute symbol from another module. The command is followed by a
2344 comma separated list of symbols to import. The command is similar to <tt>
2345 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2346 written to the generated object file, even if the symbol is never referenced
2347 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2348 references for unused symbols).
2353 .forceimport needthisone, needthistoo
2356 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2359 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2361 Declare symbols as global. Must be followed by a comma separated list of
2362 symbols to declare. Symbols from the list, that are defined somewhere in the
2363 source, are exported, all others are imported. Additional <tt><ref
2364 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2365 name=".EXPORT"></tt> commands for the same symbol are allowed.
2374 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2376 Declare symbols as global. Must be followed by a comma separated list of
2377 symbols to declare. Symbols from the list, that are defined somewhere in the
2378 source, are exported, all others are imported. Additional <tt><ref
2379 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2380 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2381 in the list are explicitly marked as zero page symbols.
2390 <sect1><tt>.I16</tt><label id=".I16"><p>
2392 Valid only in 65816 mode. Switch the index registers to 16 bit.
2394 Note: This command will not emit any code, it will tell the assembler to
2395 create 16 bit operands for immediate operands.
2397 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2398 name=".SMART"></tt> commands.
2401 <sect1><tt>.I8</tt><label id=".I8"><p>
2403 Valid only in 65816 mode. Switch the index registers to 8 bit.
2405 Note: This command will not emit any code, it will tell the assembler to
2406 create 8 bit operands for immediate operands.
2408 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2409 name=".SMART"></tt> commands.
2412 <sect1><tt>.IF</tt><label id=".IF"><p>
2414 Conditional assembly: Evaluate an expression and switch assembler output
2415 on or off depending on the expression. The expression must be a constant
2416 expression, that is, all operands must be defined.
2418 A expression value of zero evaluates to FALSE, any other value evaluates
2422 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2424 Conditional assembly: Check if there are any remaining tokens in this line,
2425 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2426 condition is not true, further lines are not assembled until an <tt><ref
2427 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2428 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2430 This command is often used to check if a macro parameter was given. Since an
2431 empty macro parameter will evaluate to nothing, the condition will evaluate
2432 to FALSE if an empty parameter was given.
2446 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2449 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2451 Conditional assembly: Evaluate an expression and switch assembler output
2452 on or off depending on the constness of the expression.
2454 A const expression evaluates to to TRUE, a non const expression (one
2455 containing an imported or currently undefined symbol) evaluates to
2458 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2461 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2463 Conditional assembly: Check if a symbol is defined. Must be followed by
2464 a symbol name. The condition is true if the the given symbol is already
2465 defined, and false otherwise.
2467 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2470 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2472 Conditional assembly: Check if there are any remaining tokens in this line,
2473 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2474 condition is not true, further lines are not assembled until an <tt><ref
2475 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2476 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2478 This command is often used to check if a macro parameter was given.
2479 Since an empty macro parameter will evaluate to nothing, the condition
2480 will evaluate to FALSE if an empty parameter was given.
2493 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2496 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2498 Conditional assembly: Check if a symbol is defined. Must be followed by
2499 a symbol name. The condition is true if the the given symbol is not
2500 defined, and false otherwise.
2502 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2505 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2507 Conditional assembly: Check if a symbol is referenced. Must be followed
2508 by a symbol name. The condition is true if if the the given symbol was
2509 not referenced before, and false otherwise.
2511 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2514 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2516 Conditional assembly: Check if the assembler is currently in 6502 mode
2517 (see <tt><ref id=".P02" name=".P02"></tt> command).
2520 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2522 Conditional assembly: Check if the assembler is currently in 65816 mode
2523 (see <tt><ref id=".P816" name=".P816"></tt> command).
2526 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2528 Conditional assembly: Check if the assembler is currently in 65C02 mode
2529 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2532 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2534 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2535 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2538 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2540 Conditional assembly: Check if a symbol is referenced. Must be followed
2541 by a symbol name. The condition is true if if the the given symbol was
2542 referenced before, and false otherwise.
2544 This command may be used to build subroutine libraries in include files
2545 (you may use separate object modules for this purpose too).
2550 .ifref ToHex ; If someone used this subroutine
2551 ToHex: tay ; Define subroutine
2557 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2560 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2562 Import a symbol from another module. The command is followed by a comma
2563 separated list of symbols to import, with each one optionally followed by
2564 an address specification.
2570 .import bar: zeropage
2573 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2576 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2578 Import a symbol from another module. The command is followed by a comma
2579 separated list of symbols to import. The symbols are explicitly imported
2580 as zero page symbols (that is, symbols with values in byte range).
2588 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2591 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2593 Include a file as binary data. The command expects a string argument
2594 that is the name of a file to include literally in the current segment.
2595 In addition to that, a start offset and a size value may be specified,
2596 separated by commas. If no size is specified, all of the file from the
2597 start offset to end-of-file is used. If no start position is specified
2598 either, zero is assumed (which means that the whole file is inserted).
2603 ; Include whole file
2604 .incbin "sprites.dat"
2606 ; Include file starting at offset 256
2607 .incbin "music.dat", $100
2609 ; Read 100 bytes starting at offset 200
2610 .incbin "graphics.dat", 200, 100
2614 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2616 Include another file. Include files may be nested up to a depth of 16.
2625 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
2627 Export a symbol and mark it as an interruptor. This may be used together
2628 with the linker to build a table of interruptor subroutines that are called
2631 Note: The linker has a feature to build a table of marked routines, but it
2632 is your code that must call these routines, so just declaring a symbol as
2633 interruptor does nothing by itself.
2635 An interruptor is always exported as an absolute (16 bit) symbol. You don't
2636 need to use an additional <tt/.export/ statement, this is implied by
2637 <tt/.interruptor/. It may have an optional priority that is separated by a
2638 comma. Higher numeric values mean a higher priority. If no priority is
2639 given, the default priority of 7 is used. Be careful when assigning
2640 priorities to your own module constructors so they won't interfere with the
2641 ones in the cc65 library.
2646 .interruptor IrqHandler
2647 .interruptor Handler, 16
2650 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
2651 section <ref id="condes" name="Module constructors/destructors"> explaining
2652 the feature in more detail.
2655 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2657 Switch on or off line continuations using the backslash character
2658 before a newline. The option is off by default.
2659 Note: Line continuations do not work in a comment. A backslash at the
2660 end of a comment is treated as part of the comment and does not trigger
2662 The command must be followed by a '+' or '-' character to switch the
2663 option on or off respectively.
2668 .linecont + ; Allow line continuations
2671 #$20 ; This is legal now
2675 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2677 Enable output to the listing. The command must be followed by a boolean
2678 switch ("on", "off", "+" or "-") and will enable or disable listing
2680 The option has no effect if the listing is not enabled by the command line
2681 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2682 to the listing file, if the counter is greater than zero, and suppressed if
2683 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2689 .list on ; Enable listing output
2693 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2695 Set, how many bytes are shown in the listing for one source line. The
2696 default is 12, so the listing will show only the first 12 bytes for any
2697 source line that generates more than 12 bytes of code or data.
2698 The directive needs an argument, which is either "unlimited", or an
2699 integer constant in the range 4..255.
2704 .listbytes unlimited ; List all bytes
2705 .listbytes 12 ; List the first 12 bytes
2706 .incbin "data.bin" ; Include large binary file
2710 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2712 This command may only be used inside a macro definition. It declares a
2713 list of identifiers as local to the macro expansion.
2715 A problem when using macros are labels: Since they don't change their name,
2716 you get a "duplicate symbol" error if the macro is expanded the second time.
2717 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2718 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2721 Some other assemblers start a new lexical block inside a macro expansion.
2722 This has some drawbacks however, since that will not allow <em/any/ symbol
2723 to be visible outside a macro, a feature that is sometimes useful. The
2724 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2725 to address the problem.
2727 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2731 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2733 Defines the character that start "cheap" local labels. You may use one
2734 of '@' and '?' as start character. The default is '@'.
2736 Cheap local labels are labels that are visible only between two non
2737 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2738 using explicit lexical nesting.
2745 Clear: lda #$00 ; Global label
2746 ?Loop: sta Mem,y ; Local label
2750 Sub: ... ; New global label
2751 bne ?Loop ; ERROR: Unknown identifier!
2755 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2757 Insert a predefined macro package. The command is followed by an
2758 identifier specifying the macro package to insert. Available macro
2762 atari Defines the scrcode macro.
2763 cbm Defines the scrcode macro.
2764 cpu Defines constants for the .CPU variable.
2765 generic Defines generic macros like add and sub.
2766 longbranch Defines conditional long jump macros.
2769 Including a macro package twice, or including a macro package that
2770 redefines already existing macros will lead to an error.
2775 .macpack longbranch ; Include macro package
2777 cmp #$20 ; Set condition codes
2778 jne Label ; Jump long on condition
2781 Macro packages are explained in more detail in section <ref
2782 id="macropackages" name="Macro packages">.
2785 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2787 Start a classic macro definition. The command is followed by an identifier
2788 (the macro name) and optionally by a comma separated list of identifiers
2789 that are macro parameters.
2791 See section <ref id="macros" name="Macros">.
2794 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2796 Start a section of absolute code. The command is followed by a constant
2797 expression that gives the new PC counter location for which the code is
2798 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2801 Please note that you <em/do not need/ this command in most cases. Placing
2802 code at a specific address is the job of the linker, not the assembler, so
2803 there is usually no reason to assemble code to a specific address.
2805 You may not switch segments while inside a section of absolute code.
2810 .org $7FF ; Emit code starting at $7FF
2814 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2816 Output a string to the console without producing an error. This command
2817 is similar to <tt/.ERROR/, however, it does not force an assembler error
2818 that prevents the creation of an object file.
2823 .out "This code was written by the codebuster(tm)"
2826 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2827 id=".ERROR" name=".ERROR"></tt> directives.
2830 <sect1><tt>.P02</tt><label id=".P02"><p>
2832 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
2833 instructions. This is the default if not overridden by the
2834 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
2836 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
2837 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2840 <sect1><tt>.P816</tt><label id=".P816"><p>
2842 Enable the 65816 instruction set. This is a superset of the 65SC02 and
2843 6502 instruction sets.
2845 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2846 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
2849 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
2851 Set the page length for the listing. Must be followed by an integer
2852 constant. The value may be "unlimited", or in the range 32 to 127. The
2853 statement has no effect if no listing is generated. The default value is -1
2854 (unlimited) but may be overridden by the <tt/--pagelength/ command line
2855 option. Beware: Since ca65 is a one pass assembler, the listing is generated
2856 after assembly is complete, you cannot use multiple line lengths with one
2857 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
2862 .pagelength 66 ; Use 66 lines per listing page
2864 .pagelength unlimited ; Unlimited page length
2868 <sect1><tt>.PC02</tt><label id=".PC02"><p>
2870 Enable the 65C02 instructions set. This instruction set includes all
2871 6502 and 65SC02 instructions.
2873 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2874 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2877 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
2879 Pop the last pushed segment from the stack, and set it.
2881 This command will switch back to the segment that was last pushed onto the
2882 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2883 command, and remove this entry from the stack.
2885 The assembler will print an error message if the segment stack is empty
2886 when this command is issued.
2888 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2891 <sect1><tt>.PROC</tt><label id=".PROC"><p>
2893 Start a nested lexical level with the given name and adds a symbol with this
2894 name to the enclosing scope. All new symbols from now on are in the local
2895 lexical level and are accessible from outside only via <ref id="scopesyntax"
2896 name="explicit scope specification">. Symbols defined outside this local
2897 level may be accessed as long as their names are not used for new symbols
2898 inside the level. Symbols names in other lexical levels do not clash, so you
2899 may use the same names for identifiers. The lexical level ends when the
2900 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
2901 may be nested up to a depth of 16 (this is an artificial limit to protect
2902 against errors in the source).
2904 Note: Macro names are always in the global level and in a separate name
2905 space. There is no special reason for this, it's just that I've never
2906 had any need for local macro definitions.
2911 .proc Clear ; Define Clear subroutine, start new level
2913 L1: sta Mem,y ; L1 is local and does not cause a
2914 ; duplicate symbol error if used in other
2917 bne L1 ; Reference local symbol
2919 .endproc ; Leave lexical level
2922 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
2926 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
2928 Enable the 65SC02 instructions set. This instruction set includes all
2931 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
2932 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2935 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
2937 Push the currently active segment onto a stack. The entries on the stack
2938 include the name of the segment and the segment type. The stack has a size
2941 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2942 to switch to another segment and to restore the old segment later, without
2943 even knowing the name and type of the current segment.
2945 The assembler will print an error message if the segment stack is already
2946 full, when this command is issued.
2948 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2951 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
2953 Switch back to relocatable mode. See the <tt><ref id=".ORG"
2954 name=".ORG"></tt> command.
2957 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
2959 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
2960 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
2961 a constant expression that tells how many times the commands in the body
2962 should get repeated. Optionally, a comma and an identifier may be specified.
2963 If this identifier is found in the body of the repeat statement, it is
2964 replaced by the current repeat count (starting with zero for the first time
2965 the body is repeated).
2967 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
2968 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
2969 level will be used, not the one from the outer level.
2973 The following macro will emit a string that is "encrypted" in that all
2974 characters of the string are XORed by the value $55.
2978 .repeat .strlen(Arg), I
2979 .byte .strat(Arg, I) ^ $55
2984 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
2987 <sect1><tt>.RES</tt><label id=".RES"><p>
2989 Reserve storage. The command is followed by one or two constant
2990 expressions. The first one is mandatory and defines, how many bytes of
2991 storage should be defined. The second, optional expression must by a
2992 constant byte value that will be used as value of the data. If there
2993 is no fill value given, the linker will use the value defined in the
2994 linker configuration file (default: zero).
2999 ; Reserve 12 bytes of memory with value $AA
3004 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3006 Switch to the RODATA segment. The name of the RODATA segment is always
3007 "RODATA", so this is a shortcut for
3013 The RODATA segment is a segment that is used by the compiler for
3014 readonly data like string constants.
3016 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3019 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3021 Start a nested lexical level with the given name. All new symbols from now
3022 on are in the local lexical level and are accessible from outside only via
3023 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3024 outside this local level may be accessed as long as their names are not used
3025 for new symbols inside the level. Symbols names in other lexical levels do
3026 not clash, so you may use the same names for identifiers. The lexical level
3027 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3028 read. Lexical levels may be nested up to a depth of 16 (this is an
3029 artificial limit to protect against errors in the source).
3031 Note: Macro names are always in the global level and in a separate name
3032 space. There is no special reason for this, it's just that I've never
3033 had any need for local macro definitions.
3038 .scope Error ; Start new scope named Error
3040 File = 1 ; File error
3041 Parse = 2 ; Parse error
3042 .endscope ; Close lexical level
3045 lda #Error::File ; Use symbol from scope Error
3048 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3052 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3054 Switch to another segment. Code and data is always emitted into a
3055 segment, that is, a named section of data. The default segment is
3056 "CODE". There may be up to 254 different segments per object file
3057 (and up to 65534 per executable). There are shortcut commands for
3058 the most common segments ("CODE", "DATA" and "BSS").
3060 The command is followed by a string containing the segment name (there are
3061 some constraints for the name - as a rule of thumb use only those segment
3062 names that would also be valid identifiers). There may also be an optional
3063 address size separated by a colon. See the section covering <tt/<ref
3064 id="address-sizes" name="address sizes">/ for more information.
3066 The default address size for a segment depends on the memory model specified
3067 on the command line. The default is "absolute", which means that you don't
3068 have to use an address size modifier in most cases.
3070 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3071 That is, the segment will reside somewhere in core memory outside the zero
3072 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3073 page and direct (short) addressing is possible for data in this segment.
3075 Beware: Only labels in a segment with the zeropage attribute are marked
3076 as reachable by short addressing. The `*' (PC counter) operator will
3077 work as in other segments and will create absolute variable values.
3079 Please note that a segment cannot have two different address sizes. A
3080 segment specified as zeropage cannot be declared as being absolute later.
3085 .segment "ROM2" ; Switch to ROM2 segment
3086 .segment "ZP2": zeropage ; New direct segment
3087 .segment "ZP2" ; Ok, will use last attribute
3088 .segment "ZP2": absolute ; Error, redecl mismatch
3091 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3092 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3093 id=".RODATA" name=".RODATA"></tt>
3096 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3098 Switch the CPU instruction set. The command is followed by a string that
3099 specifies the CPU. Possible values are those that can also be supplied to
3100 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3101 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3102 note that support for the sunplus CPU is not available in the freeware
3103 version, because the instruction set of the sunplus CPU is "proprietary
3106 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3107 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3108 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3109 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3110 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3111 <tt><ref id=".P02" name=".P02"></tt>,
3112 <tt><ref id=".P816" name=".P816"></tt>,
3113 <tt><ref id=".PC02" name=".PC02"></tt>,
3114 <tt><ref id=".PSC02" name=".PSC02"></tt>
3117 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3119 Switch on or off smart mode. The command must be followed by a '+' or '-'
3120 character to switch the option on or off respectively. The default is off
3121 (that is, the assembler doesn't try to be smart), but this default may be
3122 changed by the -s switch on the command line.
3124 In smart mode the assembler will do the following:
3127 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3128 and update the operand sizes accordingly. If the operand of such an
3129 instruction cannot be evaluated by the assembler (for example, because
3130 the operand is an imported symbol), a warning is issued. Beware: Since
3131 the assembler cannot trace the execution flow this may lead to false
3132 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3133 instructions to tell the assembler about the current settings.
3134 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3135 used within a procedure declared as <tt/far/, or if the procedure has
3136 no explicit address specification, but it is <tt/far/ because of the
3144 .smart - ; Stop being smart
3147 See: <tt><ref id=".A16" name=".A16"></tt>,
3148 <tt><ref id=".A8" name=".A8"></tt>,
3149 <tt><ref id=".I16" name=".I16"></tt>,
3150 <tt><ref id=".I8" name=".I8"></tt>
3153 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3155 Starts a struct definition. Structs are covered in a separate section named
3156 <ref id="structs" name=""Structs and unions"">.
3158 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3161 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3163 Enable the SunPlus instructions set. This command will not work in the
3164 freeware version of the assembler, because the instruction set is
3165 "proprietary and confidential".
3167 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3168 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3169 <tt><ref id=".P816" name=".P816"></tt>
3172 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3174 Allocate space for a struct or union.
3185 .tag Point ; Allocate 4 bytes
3189 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3191 Force an assembly warning. The assembler will output a warning message
3192 preceded by "User warning". This warning will always be output, even if
3193 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3194 command line option.
3196 This command may be used to output possible problems when assembling
3205 .warning "Forward jump in jne, cannot optimize!"
3215 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
3216 name=".OUT"></tt> directives.
3219 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3221 Define word sized data. Must be followed by a sequence of (word ranged,
3222 but not necessarily constant) expressions.
3227 .word $0D00, $AF13, _Clear
3231 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3233 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3234 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3238 .segment "ZEROPAGE", zeropage
3241 Because of the "zeropage" attribute, labels declared in this segment are
3242 addressed using direct addressing mode if possible. You <em/must/ instruct
3243 the linker to place this segment somewhere in the address range 0..$FF
3244 otherwise you will get errors.
3246 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3250 <sect>Macros<label id="macros"><p>
3253 <sect1>Introduction<p>
3255 Macros may be thought of as "parametrized super instructions". Macros are
3256 sequences of tokens that have a name. If that name is used in the source
3257 file, the macro is "expanded", that is, it is replaced by the tokens that
3258 were specified when the macro was defined.
3261 <sect1>Macros without parameters<p>
3263 In it's simplest form, a macro does not have parameters. Here's an
3267 .macro asr ; Arithmetic shift right
3268 cmp #$80 ; Put bit 7 into carry
3269 ror ; Rotate right with carry
3273 The macro above consists of two real instructions, that are inserted into
3274 the code, whenever the macro is expanded. Macro expansion is simply done
3275 by using the name, like this:
3284 <sect1>Parametrized macros<p>
3286 When using macro parameters, macros can be even more useful:
3300 When calling the macro, you may give a parameter, and each occurrence of
3301 the name "addr" in the macro definition will be replaced by the given
3320 A macro may have more than one parameter, in this case, the parameters
3321 are separated by commas. You are free to give less parameters than the
3322 macro actually takes in the definition. You may also leave intermediate
3323 parameters empty. Empty parameters are replaced by empty space (that is,
3324 they are removed when the macro is expanded). If you have a look at our
3325 macro definition above, you will see, that replacing the "addr" parameter
3326 by nothing will lead to wrong code in most lines. To help you, writing
3327 macros with a variable parameter list, there are some control commands:
3329 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3330 returns true, if there are any tokens on the remainder of the line. Since
3331 empty parameters are replaced by nothing, this may be used to test if a given
3332 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3335 Look at this example:
3338 .macro ldaxy a, x, y
3351 This macro may be called as follows:
3354 ldaxy 1, 2, 3 ; Load all three registers
3356 ldaxy 1, , 3 ; Load only a and y
3358 ldaxy , , 3 ; Load y only
3361 There's another helper command for determining, which macro parameters are
3362 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3363 replaced by the parameter count given, <em/including/ intermediate empty macro
3367 ldaxy 1 ; .PARAMCOUNT = 1
3368 ldaxy 1,,3 ; .PARAMCOUNT = 3
3369 ldaxy 1,2 ; .PARAMCOUNT = 2
3370 ldaxy 1, ; .PARAMCOUNT = 2
3371 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3374 Macro parameters may optionally be enclosed into curly braces. This allows the
3375 inclusion of tokens that would otherwise terminate the parameter (the comma in
3376 case of a macro parameter).
3379 .macro foo arg1, arg2
3383 foo ($00,x) ; Two parameters passed
3384 foo {($00,x)} ; One parameter passed
3387 In the first case, the macro is called with two parameters: '<tt/($00/'
3388 and 'x)'. The comma is not passed to the macro, since it is part of the
3389 calling sequence, not the parameters.
3391 In the second case, '($00,x)' is passed to the macro, this time
3392 including the comma.
3395 <sect1>Detecting parameter types<p>
3397 Sometimes it is nice to write a macro that acts differently depending on the
3398 type of the argument supplied. An example would be a macro that loads a 16 bit
3399 value from either an immediate operand, or from memory. The <tt/<ref
3400 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3401 functions will allow you to do exactly this:
3405 .if (.match (.left (1, {arg}), #))
3407 lda #<(.right (.tcount ({arg})-1, {arg}))
3408 ldx #>(.right (.tcount ({arg})-1, {arg}))
3410 ; assume absolute or zero page
3417 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3418 check if its argument begins with a hash mark. If so, two immediate loads are
3419 emitted, Otherwise a load from an absolute zero page memory location is
3420 assumed. Please note how the curly braces are used to enclose parameters to
3421 pseudo functions handling token lists. This is necessary, because the token
3422 lists may include commas or parens, which would be treated by the assembler
3425 The macro can be used as
3430 ldax #$1234 ; X=$12, A=$34
3432 ldax foo ; X=$56, A=$78
3436 <sect1>Recursive macros<p>
3438 Macros may be used recursively:
3441 .macro push r1, r2, r3
3450 There's also a special macro to help writing recursive macros: <tt><ref
3451 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3455 .macro push r1, r2, r3, r4, r5, r6, r7
3457 ; First parameter is empty
3463 push r2, r3, r4, r5, r6, r7
3467 When expanding this macro, the expansion will push all given parameters
3468 until an empty one is encountered. The macro may be called like this:
3471 push $20, $21, $32 ; Push 3 ZP locations
3472 push $21 ; Push one ZP location
3476 <sect1>Local symbols inside macros<p>
3478 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3479 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3480 Have a look at the inc16 macro above. Here is it again:
3494 If you have a closer look at the code, you will notice, that it could be
3495 written more efficiently, like this:
3506 But imagine what happens, if you use this macro twice? Since the label
3507 "Skip" has the same name both times, you get a "duplicate symbol" error.
3508 Without a way to circumvent this problem, macros are not as useful, as
3509 they could be. One solution is, to start a new lexical block inside the
3523 Now the label is local to the block and not visible outside. However,
3524 sometimes you want a label inside the macro to be visible outside. To make
3525 that possible, there's a new command that's only usable inside a macro
3526 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3527 or more symbols as local to the macro expansion. The names of local variables
3528 are replaced by a unique name in each separate macro expansion. So we could
3529 also solve the problem above by using <tt/.LOCAL/:
3533 .local Skip ; Make Skip a local symbol
3540 Skip: ; Not visible outside
3545 <sect1>C style macros<p>
3547 Starting with version 2.5 of the assembler, there is a second macro type
3548 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3549 similar to the classic macro type described above, but behaviour is sometimes
3554 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3555 span more than a line. You may use line continuation (see <tt><ref
3556 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3557 more than one line for increased readability, but the macro itself
3558 may not contain an end-of-line token.
3560 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3561 the name space with classic macros, but they are detected and replaced
3562 at the scanner level. While classic macros may be used in every place,
3563 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3564 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3565 they are more versatile in some situations.
3567 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3568 parameters. While classic macros may have empty parameters, this is
3569 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3570 For this macro type, the number of actual parameters must match
3571 exactly the number of formal parameters.
3573 To make this possible, formal parameters are enclosed in braces when
3574 defining the macro. If there are no parameters, the empty braces may
3577 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3578 contain end-of-line tokens, there are things that cannot be done. They
3579 may not contain several processor instructions for example. So, while
3580 some things may be done with both macro types, each type has special
3581 usages. The types complement each other.
3585 Let's look at a few examples to make the advantages and disadvantages
3588 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3589 following <tt/.DEFINE/:
3594 foo EQU $1234 ; This is accepted now
3597 You may use the directive to define string constants used elsewhere:
3600 ; Define the version number
3601 .define VERSION "12.3a"
3607 Macros with parameters may also be useful:
3610 .define DEBUG(message) .out message
3612 DEBUG "Assembling include file #3"
3615 Note that, while formal parameters have to be placed in braces, this is
3616 not true for the actual parameters. Beware: Since the assembler cannot
3617 detect the end of one parameter, only the first token is used. If you
3618 don't like that, use classic macros instead:
3626 (This is an example where a problem can be solved with both macro types).
3629 <sect1>Characters in macros<p>
3631 When using the <ref id="option-t" name="-t"> option, characters are translated
3632 into the target character set of the specific machine. However, this happens
3633 as late as possible. This means that strings are translated if they are part
3634 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3635 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3636 used as part of an expression.
3638 This behaviour is very intuitive outside of macros but may be confusing when
3639 doing more complex macros. If you compare characters against numeric values,
3640 be sure to take the translation into account.
3645 <sect>Macro packages<label id="macropackages"><p>
3647 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3648 macro packages may be included with just one command. Available macro packages
3652 <sect1><tt>.MACPACK generic</tt><p>
3654 This macro package defines macros that are useful in almost any program.
3655 Currently, two macros are defined:
3670 <sect1><tt>.MACPACK longbranch</tt><p>
3672 This macro package defines long conditional jumps. They are named like the
3673 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3674 definition for the "<tt/jeq/" macro, the other macros are built using the same
3679 .if .def(Target) .and ((*+2)-(Target) <= 127)
3688 All macros expand to a short branch, if the label is already defined (back
3689 jump) and is reachable with a short jump. Otherwise the macro expands to a
3690 conditional branch with the branch condition inverted, followed by an absolute
3691 jump to the actual branch target.
3693 The package defines the following macros:
3696 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3701 <sect1><tt>.MACPACK cbm</tt><p>
3703 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3704 string as argument and places this string into memory translated into screen
3708 <sect1><tt>.MACPACK cpu</tt><p>
3710 This macro package does not define any macros but constants used to examine
3711 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3712 each supported CPU a constant similar to
3724 is defined. These constants may be used to determine the exact type of the
3725 currently enabled CPU. In addition to that, for each CPU instruction set,
3726 another constant is defined:
3738 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3739 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3740 currently enabled CPU supports a specific instruction set. For example the
3741 65C02 supports all instructions of the 65SC02 CPU, so it has the
3742 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3746 .if (.cpu .bitand CPU_ISET_65SC02)
3754 it is possible to determine if the
3760 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3761 CPUs (the latter two are upwards compatible to the 65SC02).
3765 <sect>Predefined constants<label id="predefined-constants"><p>
3767 For better orthogonality, the assembler defines similar symbols as the
3768 compiler, depending on the target system selected:
3771 <item><tt/__ACE__/ - Target system is <tt/ace/
3772 <item><tt/__APPLE2__",/ - Target system is <tt/apple2/
3773 <item><tt/__APPLE2ENH__",/ - Target system is <tt/apple2enh/
3774 <item><tt/__ATARI__/ - Target system is <tt/atari/
3775 <item><tt/__ATMOS__",/ - Target system is <tt/atmos/
3776 <item><tt/__BBC__",/ - Target system is <tt/bbc/
3777 <item><tt/__C128__/ - Target system is <tt/c128/
3778 <item><tt/__C16__/ - Target system is <tt/c16/
3779 <item><tt/__C64__/ - Target system is <tt/c64/
3780 <item><tt/__CBM__/ - Target is a Commodore system
3781 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
3782 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
3783 <item><tt/__GEOS__",/ - Target system is <tt/geos/
3784 <item><tt/__LUNIX__",/ - Target system is <tt/lunix/
3785 <item><tt/__NES__",/ - Target system is <tt/nes/
3786 <item><tt/__PET__/ - Target system is <tt/pet/
3787 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
3788 <item><tt/__SUPERVISION__",/ - Target system is <tt/supervision/
3789 <item><tt/__VIC20__/ - Target system is <tt/vic20/
3793 <sect>Structs and unions<label id="structs"><p>
3797 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3798 are to some degree comparable to their C counterparts. Both have a list of
3799 members. Each member allocates storage and may optionally have a name, which,
3800 in case of a struct, is the offset from the beginning and, in case of a union,
3804 <sect1>Declaration<p>
3806 Here is an example for a very simple struct with two members and a total size
3816 A union shares the total space between all its members, its size is the same
3817 as that of the largest member.
3819 A struct or union must not necessarily have a name. If it is anonymous, no
3820 local scope is opened, the identifiers used to name the members are placed
3821 into the current scope instead.
3823 A struct may contain unnamed members and definitions of local structs. The
3824 storage allocators may contain a multiplier, as in the example below:
3829 .word 2 ; Allocate two words
3836 <sect1>The <tt/.TAG/ keyword<p>
3838 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
3839 for an already defined struct or unions within another struct:
3853 Space for a struct or union may be allocated using the <ref id=".TAG"
3854 name=".TAG"> directive.
3860 Currently, members are just offsets from the start of the struct or union. To
3861 access a field of a struct, the member offset has to be added to the address
3862 of the struct itself:
3865 lda C+Circle::Radius ; Load circle radius into A
3868 This may change in a future version of the assembler.
3871 <sect1>Limitations<p>
3873 Structs and unions are currently implemented as nested symbol tables (in fact,
3874 they were a by-product of the improved scoping rules). Currently, the
3875 assembler has no idea of types. This means that the <ref id=".TAG"
3876 name=".TAG"> keyword will only allocate space. You won't be able to initialize
3877 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
3878 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
3879 this structure accessible by using the '::' operator.
3883 <sect>Module constructors/destructors<label id="condes"><p>
3885 <em>Note:</em> This section applies mostly to C programs, so the explanation
3886 below uses examples from the C libraries. However, the feature may also be
3887 useful for assembler programs.
3892 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
3893 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
3894 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
3895 special way. The linker is able to generate tables with all functions of a
3896 specific type. Such a table will <em>only</em> include symbols from object
3897 files that are linked into a specific executable. This may be used to add
3898 initialization and cleanup code for library modules, or a table of interrupt
3901 The C heap functions are an example where module initialization code is used.
3902 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
3903 variables that contain the start and the end of the heap, pointers to the free
3904 list and so on. Since the end of the heap depends on the size and start of the
3905 stack, it must be initialized at runtime. However, initializing these
3906 variables for programs that do not use the heap are a waste of time and
3909 So the central module defines a function that contains initialization code and
3910 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
3911 this module is added to an executable by the linker, the initialization
3912 function will be placed into the table of constructors by the linker. The C
3913 startup code will call all constructors before <tt/main/ and all destructors
3914 after <tt/main/, so without any further work, the heap initialization code is
3915 called once the module is linked in.
3917 While it would be possible to add explicit calls to initialization functions
3918 in the startup code, the new approach has several advantages:
3922 If a module is not included, the initialization code is not linked in and not
3923 called. So you don't pay for things you don't need.
3926 Adding another library that needs initialization does not mean that the
3927 startup code has to be changed. Before we had module constructors and
3928 destructors, the startup code for all systems had to be adjusted to call the
3929 new initialization code.
3932 The feature saves memory: Each additional initialization function needs just
3933 two bytes in the table (a pointer to the function).
3938 <sect1>Calling order<p>
3940 The symbols are sorted in increasing priority order by the linker when using
3941 one of the builtin linker configurations, so the functions with lower
3942 priorities come first and are followed by those with higher priorities. The C
3943 library runtime subroutine that walks over the function tables calls the
3944 functions starting from the top of the table - which means that functions with
3945 a high priority are called first.
3947 So when using the C runtime, functions are called with high priority functions
3948 first, followed by low priority functions.
3953 When using these special symbols, please take care of the following:
3958 The linker will only generate function tables, it will not generate code to
3959 call these functions. If you're using the feature in some other than the
3960 existing C environments, you have to write code to call all functions in a
3961 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
3962 in the C runtime for an example on how to do this.
3965 The linker will only add addresses of functions that are in modules linked to
3966 the executable. This means that you have to be careful where to place the
3967 condes functions. If initialization or an irq handler is needed for a group of
3968 functions, be sure to place the function into a module that is linked in
3969 regardless of which function is called by the user.
3972 The linker will generate the tables only when requested to do so by the
3973 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
3974 be requested separately.
3977 Constructors and destructors may have priorities. These priorities determine
3978 the order of the functions in the table. If your initialization or cleanup code
3979 does depend on other initialization or cleanup code, you have to choose the
3980 priority for the functions accordingly.
3983 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
3984 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
3985 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
3986 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
3987 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
3988 (interruptor). The linker generates a separate table for each type on request.
3993 <sect>Porting sources from other assemblers<p>
3995 Sometimes it is necessary to port code written for older assemblers to ca65.
3996 In some cases, this can be done without any changes to the source code by
3997 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
3998 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4001 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4002 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4003 done by the linker. Most other assemblers generate absolute code, placement is
4004 done within the assembler and there is no external linker.
4006 In general it is not a good idea to write new code using the emulation
4007 features of the assembler, but there may be situations where even this rule is
4012 You need to use some of the ca65 emulation features to simulate the behaviour
4013 of such simple assemblers.
4016 <item>Prepare your sourcecode like this:
4019 ; if you want TASS style labels without colons
4020 .feature labels_without_colons
4022 ; if you want TASS style character constants
4023 ; ("a" instead of the default 'a')
4024 .feature loose_char_term
4026 .word *+2 ; the cbm load address
4031 notice that the two emulation features are mostly useful for porting
4032 sources originally written in/for TASS, they are not needed for the
4033 actual "simple assembler operation" and are not recommended if you are
4034 writing new code from scratch.
4036 <item>Replace all program counter assignments (which are not possible in ca65
4037 by default, and the respective emulation feature works different from what
4038 you'd expect) by another way to skip to memory locations, for example the
4039 <tt><ref id=".RES" name=".RES"></tt> directive.
4043 .res $2000-* ; reserve memory up to $2000
4046 Please note that other than the original TASS, ca65 can never move the program
4047 counter backwards - think of it as if you are assembling to disk with TASS.
4049 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4050 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4051 of <tt/.goto/, everything involving loops must be replaced by
4052 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4054 <item>To assemble code to a different address than it is executed at, use the
4055 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4056 <tt/.offs/-constructs.
4063 .reloc ; back to normal
4066 <item>Then assemble like this:
4069 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4072 Note that you need to use the actual start address minus two, since two bytes
4073 are used for the cbm load address.
4078 <sect>Bugs/Feedback<p>
4080 If you have problems using the assembler, if you find any bugs, or if
4081 you're doing something interesting with the assembler, I would be glad to
4082 hear from you. Feel free to contact me by email
4083 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4089 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4090 Bassewitz. For usage of the binaries and/or sources the following
4091 conditions do apply:
4093 This software is provided 'as-is', without any expressed or implied
4094 warranty. In no event will the authors be held liable for any damages
4095 arising from the use of this software.
4097 Permission is granted to anyone to use this software for any purpose,
4098 including commercial applications, and to alter it and redistribute it
4099 freely, subject to the following restrictions:
4102 <item> The origin of this software must not be misrepresented; you must not
4103 claim that you wrote the original software. If you use this software
4104 in a product, an acknowledgment in the product documentation would be
4105 appreciated but is not required.
4106 <item> Altered source versions must be plainly marked as such, and must not
4107 be misrepresented as being the original software.
4108 <item> This notice may not be removed or altered from any source