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>19.07.2000, 29.11.2000, 02.10.2001
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 -o name Name the output file
101 -t sys Set the target system
102 -v Increase verbosity
105 --auto-import Mark unresolved symbols as import
106 --cpu type Set cpu type
107 --debug-info Add debug info to object file
108 --feature name Set an emulation feature
109 --help Help (this text)
110 --ignore-case Ignore case of symbols
111 --include-dir dir Set an include directory search path
112 --list-bytes n Maximum number of bytes per listing line
113 --listing Create a listing if assembly was ok
114 --pagelength n Set the page length for the listing
115 --smart Enable smart mode
116 --target sys Set the target system
117 --verbose Increase verbosity
118 --version Print the assembler version
119 ---------------------------------------------------------------------------
123 <sect1>Command line options in detail<p>
125 Here is a description of all the command line options:
129 <label id="option--cpu">
130 <tag><tt>--cpu type</tt></tag>
132 Set the default for the CPU type. The option takes a parameter, which
135 6502, 65SC02, 65C02, 65816, sunplus, sweet16
137 The sunplus cpu is not available in the freeware version, because the
138 instruction set is "proprietary and confidential".
141 <label id="option--feature">
142 <tag><tt>--feature name</tt></tag>
144 Enable an emulation feature. This is identical as using <tt/.FEATURE/
145 in the source with two exceptions: Feature names must be lower case, and
146 each feature must be specified by using an extra <tt/--feature/ option,
147 comma separated lists are not allowed.
149 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
150 command for a list of emulation features.
153 <label id="option-g">
154 <tag><tt>-g, --debug-info</tt></tag>
156 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
157 used, the assembler will add a section to the object file that contains
158 all symbols (including local ones) together with the symbol values and
159 source file positions. The linker will put these additional symbols into
160 the VICE label file, so even local symbols can be seen in the VICE
164 <tag><tt>-h, --help</tt></tag>
166 Print the short option summary shown above.
169 <tag><tt>-i, --ignore-case</tt></tag>
171 This option makes the assembler case insensitive on identifiers and labels.
172 This option will override the default, but may itself be overridden by the
173 <tt><ref id=".CASE" name=".CASE"></tt> control command.
176 <tag><tt>-l, --listing</tt></tag>
178 Generate an assembler listing. The listing file will always have the
179 name of the main input file with the extension replaced by ".lst". This
180 may change in future versions.
183 <tag><tt>--list-bytes n</tt></tag>
185 Set the maximum number of bytes printed in the listing for one line of
186 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
187 for more information. The value zero can be used to encode an unlimited
188 number of printed bytes.
191 <tag><tt>-o name</tt></tag>
193 The default output name is the name of the input file with the extension
194 replaced by ".o". If you don't like that, you may give another name with
195 the -o option. The output file will be placed in the same directory as
196 the source file, or, if -o is given, the full path in this name is used.
199 <tag><tt>--pagelength n</tt></tag>
201 sets the length of a listing page in lines. See the <tt><ref
202 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
205 <tag><tt>-s, --smart-mode</tt></tag>
207 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
208 pseudo instruction) the assembler will track usage of the <tt/REP/ and
209 <tt/SEP/ instructions in 65816 mode and update the operand sizes
210 accordingly. If the operand of such an instruction cannot be evaluated by
211 the assembler (for example, because the operand is an imported symbol), a
214 Beware: Since the assembler cannot trace the execution flow this may
215 lead to false results in some cases. If in doubt, use the .ixx and .axx
216 instructions to tell the assembler about the current settings. Smart
217 mode is off by default.
220 <label id="option-t">
221 <tag><tt>-t sys, --target sys</tt></tag>
223 Set the target system. This will enable translation of character strings
224 and character constants into the character set of the target platform.
225 The default for the target system is "none", which means that no translation
226 will take place. The assembler supports the same target systems as the
227 compiler, see there for a list.
230 <tag><tt>-v, --verbose</tt></tag>
232 Increase the assembler verbosity. Usually only needed for debugging
233 purposes. You may use this option more than one time for even more
237 <tag><tt>-D</tt></tag>
239 This option allows you to define symbols on the command line. Without a
240 value, the symbol is defined with the value zero. When giving a value,
241 you may use the '$' prefix for hexadecimal symbols. Please note
242 that for some operating systems, '$' has a special meaning, so
243 you may have to quote the expression.
246 <tag><tt>-I dir, --include-dir dir</tt></tag>
248 Name a directory which is searched for include files. The option may be
249 used more than once to specify more than one directory to search. The
250 current directory is always searched first before considering any
251 additional directories.
254 <tag><tt>-U, --auto-import</tt></tag>
256 Mark symbols that are not defined in the sources as imported symbols. This
257 should be used with care since it delays error messages about typos and such
258 until the linker is run. The compiler uses the equivalent of this switch
259 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
260 symbols for the runtime library. However, the compiler is supposed to
261 generate code that runs through the assembler without problems, something
262 which is not always true for assembler programmers.
265 <tag><tt>-V, --version</tt></tag>
267 Print the version number of the assembler. If you send any suggestions
268 or bugfixes, please include the version number.
271 <label id="option-W">
272 <tag><tt>-Wn</tt></tag>
274 Set the warning level for the assembler. Using -W2 the assembler will
275 even warn about such things like unused imported symbols. The default
276 warning level is 1, and it would probably be silly to set it to
283 <sect>Input format<p>
285 <sect1>Assembler syntax<p>
287 The assembler accepts the standard 6502/65816 assembler syntax. One line may
288 contain a label (which is identified by a colon), and, in addition to the
289 label, an assembler mnemonic, a macro, or a control command (see section <ref
290 id="control-commands" name="Control Commands"> for supported control
291 commands). Alternatively, the line may contain a symbol definition using
292 the '=' token. Everything after a semicolon is handled as a comment (that is,
295 Here are some examples for valid input lines:
298 Label: ; A label and a comment
299 lda #$20 ; A 6502 instruction plus comment
300 L1: ldx #$20 ; Same with label
301 L2: .byte "Hello world" ; Label plus control command
302 mymac $20 ; Macro expansion
303 MySym = 3*L1 ; Symbol definition
304 MaSym = Label ; Another symbol
307 The assembler accepts
310 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
311 <tt><ref id=".P02" name=".P02"></tt> command was given).
312 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
313 <ref id="6502X-mode" name="6502X mode">.
314 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
315 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
316 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
317 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
318 <item>all valid 65618 mnemonics when in 65816 mode (after the
319 <tt><ref id=".P816" name=".P816"></tt> command was given).
320 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
321 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
327 In 65816 mode several aliases are accepted in addition to the official
331 BGE is an alias for BCS
332 BLT is an alias for BCC
333 CPA is an alias for CMP
334 DEA is an alias for DEC A
335 INA is an alias for INC A
336 SWA is an alias for XBA
337 TAD is an alias for TCD
338 TAS is an alias for TCS
339 TDA is an alias for TDC
340 TSA is an alias for TSC
345 <sect1>6502X mode<label id="6502X-mode"><p>
347 6502X mode is an extension to the normal 6502 mode. In this mode, several
348 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
349 these instructions are illegal, there are no official mnemonics for them. The
350 unofficial ones are taken from <htmlurl
351 url="http://oxyron.net/graham/opcodes02.html"
352 name="http://oxyron.net/graham/opcodes02.html">. Please note that only the
353 ones marked as "stable" are supported. The following table uses information
354 from the mentioned web page, for more information, see there.
357 <item><tt>ALR: A:=(A and #{imm})*2;</tt>
358 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
359 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
360 <item><tt>AXS: X:=A and X-#{imm};</tt>
361 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
362 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
363 <item><tt>LAS: A,X,S:={adr} and S;</tt>
364 <item><tt>LAX: A,X:={adr};</tt>
365 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
366 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
367 <item><tt>SAX: {adr}:=A and X;</tt>
368 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
369 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
374 <sect1>sweet16 mode<label id="sweet16-mode"><p>
376 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
377 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
378 generate code for this pseudo CPU when switched into sweet16 mode. The
379 following is special in sweet16 mode:
383 <item>The '@' character denotes indirect addressing and is no longer available
384 for cheap local labels. If you need cheap local labels, you will have to
385 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
386 name=".LOCALCHAR">/ command.
388 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
389 these identifiers are reserved words.
393 Please note that the assembler does neither supply the interpreter needed for
394 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
395 nor does it call the interpreter. All this must be done by your program. Apple
396 ][ programmers do probably know how to use sweet16 mode.
398 For more information about SWEET 16, see
399 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
400 name="http://www.6502.org/source/interpreters/sweet16.htm">.
403 <sect1>Number format<p>
405 For literal values, the assembler accepts the widely used number formats: A
406 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
407 denotes a binary value, and a bare number is interpreted as a decimal. There
408 are currently no octal values and no floats.
411 <sect1>Conditional assembly<p>
413 Please note that when using the conditional directives (<tt/.IF/ and friends),
414 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
415 that are not assembled. The reason for this behaviour is that the assembler
416 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
417 conversion of the input stream into tokens still takes place. As a consequence
418 conditional assembly directives may <bf/not/ be used to prevent normal text
419 (used as a comment or similar) from being assembled. <p>
425 <sect1>Expression evaluation<p>
427 All expressions are evaluated with (at least) 32 bit precision. An
428 expression may contain constant values and any combination of internal and
429 external symbols. Expressions that cannot be evaluated at assembly time
430 are stored inside the object file for evaluation by the linker.
431 Expressions referencing imported symbols must always be evaluated by the
435 <sect1>Size of an expression result<p>
437 Sometimes, the assembler must know about the size of the value that is the
438 result of an expression. This is usually the case, if a decision has to be
439 made, to generate a zero page or an absolute memory references. In this
440 case, the assembler has to make some assumptions about the result of an
444 <item> If the result of an expression is constant, the actual value is
445 checked to see if it's a byte sized expression or not.
446 <item> If the expression is explicitly casted to a byte sized expression by
447 one of the '>', '<' or '^' operators, it is a byte expression.
448 <item> If this is not the case, and the expression contains a symbol,
449 explicitly declared as zero page symbol (by one of the .importzp or
450 .exportzp instructions), then the whole expression is assumed to be
452 <item> If the expression contains symbols that are not defined, and these
453 symbols are local symbols, the enclosing scopes are searched for a
454 symbol with the same name. If one exists and this symbol is defined,
455 it's attributes are used to determine the result size.
456 <item> In all other cases the expression is assumed to be word sized.
459 Note: If the assembler is not able to evaluate the expression at assembly
460 time, the linker will evaluate it and check for range errors as soon as
464 <sect1>Boolean expressions<p>
466 In the context of a boolean expression, any non zero value is evaluated as
467 true, any other value to false. The result of a boolean expression is 1 if
468 it's true, and zero if it's false. There are boolean operators with extreme
469 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
470 operators are shortcut operators. That is, if the result of the expression is
471 already known, after evaluating the left hand side, the right hand side is
475 <sect1>Constant expressions<p>
477 Sometimes an expression must evaluate to a constant without looking at any
478 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
479 that decides if parts of the code are assembled or not. An expression used in
480 the <tt/.IF/ command cannot reference a symbol defined later, because the
481 decision about the <tt/.IF/ must be made at the point when it is read. If the
482 expression used in such a context contains only constant numerical values,
483 there is no problem. When unresolvable symbols are involved it may get harder
484 for the assembler to determine if the expression is actually constant, and it
485 is even possible to create expressions that aren't recognized as constant.
486 Simplifying the expressions will often help.
488 In cases where the result of the expression is not needed immediately, the
489 assembler will delay evaluation until all input is read, at which point all
490 symbols are known. So using arbitrary complex constant expressions is no
491 problem in most cases.
495 <sect1>Available operators<label id="operators"><p>
497 Available operators sorted by precedence:
500 Op Description Precedence
501 -------------------------------------------------------------------
502 Builtin string functions 0
504 Builtin pseudo variables 1
505 Builtin pseudo functions 1
508 ~ Unary bitwise not 1
509 .BITNOT Unary bitwise not 1
510 < Low byte operator 1
511 > High byte operator 1
512 ^ Bank byte operator 1
516 .MOD Modulo operation 2
518 .BITAND Bitwise and 2
520 .BITXOR Bitwise xor 2
521 << Shift left operator 2
522 .SHL Shift left operator 2
523 >> Shift right operator
524 .SHR Shift right operator 2
531 = Compare operation (equal) 4
532 <> Compare operation (not equal) 4
533 < Compare operation (less) 4
534 > Compare operation (greater) 4
535 <= Compare operation (less or equal) 4
536 >= Compare operation (greater or equal) 4
538 && Boolean and 5
550 To force a specific order of evaluation, braces may be used as usual.
556 <sect>Symbols and labels<p>
558 The assembler allows you to use symbols instead of naked values to make
559 the source more readable. There are a lot of different ways to define and
560 use symbols and labels, giving a lot of flexibility.
563 <sect1>Numeric constants<p>
565 Numeric constants are defined using the equal sign or the label assignment
566 operator. After doing
572 may use the symbol "two" in every place where a number is expected, and it is
573 evaluated to the value 2 in this context. The label assignment operator causes
574 the same, but causes the symbol to be marked as a label, which may cause a
575 different handling in the debugger:
581 The right side can of course be an expression:
588 <sect1>Standard labels<p>
590 A label is defined by writing the name of the label at the start of the line
591 (before any instruction mnemonic, macro or pseudo directive), followed by a
592 colon. This will declare a symbol with the given name and the value of the
593 current program counter.
596 <sect1>Local labels and symbols<p>
598 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
599 create regions of code where the names of labels and symbols are local to this
600 region. They are not known outside of this region and cannot be accessed from
601 there. Such regions may be nested like PROCEDUREs in Pascal.
603 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
604 directive for more information.
607 <sect1>Cheap local labels<p>
609 Cheap local labels are defined like standard labels, but the name of the
610 label must begin with a special symbol (usually '@', but this can be
611 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
614 Cheap local labels are visible only between two non cheap labels. As soon as a
615 standard symbol is encountered (this may also be a local symbol if inside a
616 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
617 cheap local symbol goes out of scope.
619 You may use cheap local labels as an easy way to reuse common label
620 names like "Loop". Here is an example:
623 Clear: lda #$00 ; Global label
625 @Loop: sta Mem,y ; Local label
629 Sub: ... ; New global label
630 bne @Loop ; ERROR: Unknown identifier!
633 <sect1>Unnamed labels<p>
635 If you really want to write messy code, there are also unnamed labels. These
636 labels do not have a name (you guessed that already, didn't you?). A colon is
637 used to mark the absence of the name.
639 Unnamed labels may be accessed by using the colon plus several minus or plus
640 characters as a label designator. Using the '-' characters will create a back
641 reference (use the n'th label backwards), using '+' will create a forward
642 reference (use the n'th label in forward direction). An example will help to
665 As you can see from the example, unnamed labels will make even short
666 sections of code hard to understand, because you have to count labels
667 to find branch targets (this is the reason why I for my part do
668 prefer the "cheap" local labels). Nevertheless, unnamed labels are
669 convenient in some situations, so it's your decision.
672 <sect1>Using macros to define labels and constants<p>
674 While there are drawbacks with this approach, it may be handy in some
675 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
676 possible to define symbols or constants that may be used elsewhere. Since
677 the macro facility works on a very low level, there is no scoping. On the
678 other side, you may also define string constants this way (this is not
679 possible with the other symbol types).
685 .DEFINE version "SOS V2.3"
687 four = two * two ; Ok
690 .PROC ; Start local scope
691 two = 3 ; Will give "2 = 3" - invalid!
696 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
698 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
699 id="option-g" name="-g"> is given on the command line), global, local and
700 cheap local labels are written to the object file and will be available in the
701 symbol file via the linker. Unnamed labels are not written to the object file,
702 because they don't have a name which would allow to access them.
706 <sect>Scopes<label id="scopes"><p>
708 ca65 implements several sorts of scopes for symbols.
710 <sect1>Global scope<p>
712 All (non cheap local) symbols that are declared outside of any nested scopes
716 <sect1>Cheap locals<p>
718 A special scope is the scope for cheap local symbols. It lasts from one non
719 local symbol to the next one, without any provisions made by the programmer.
720 All other scopes differ in usage but use the same concept internally.
723 <sect1>Generic nested scopes<p>
725 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
726 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
727 The scope can have a name, in which case it is accessible from the outside by
728 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
729 have a name, all symbols created within the scope are local to the scope, and
730 aren't accessible from the outside.
732 A nested scope can access symbols from the local or from enclosing scopes by
733 name without using explicit scope names. In some cases there may be
734 ambiguities, for example if there is a reference to a local symbol that is not
735 yet defined, but a symbol with the same name exists in outer scopes:
747 In the example above, the <tt/lda/ instruction will load the value 3 into the
748 accumulator, because <tt/foo/ is redefined in the scope. However:
760 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
761 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
762 absolute mode is used instead. In fact, the assembler will not use absolute
763 mode by default, but it will search through the enclosing scopes for a symbol
764 with the given name. If one is found, the address size of this symbol is used.
765 This may lead to errors:
777 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
778 instruction, it will search for an already defined symbol <tt/foo/. It will
779 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
780 zeropage symbol. So the assembler will use zeropage addressing mode. If
781 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
782 the address in the <tt/lda/ instruction already translated, but since the new
783 value needs absolute addressing mode, this fails, and an error message "Range
786 Of course the most simple solution for the problem is to move the definition
787 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
788 rare cases when this cannot be done. In these cases, you can use one of the
789 address size override operators:
801 This will cause the <tt/lda/ instruction to be translated using absolute
802 addressing mode, which means changing the symbol reference later does not
806 <sect1>Nested procedures<p>
808 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
809 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
810 name, and a it will introduce a symbol with this name in the enclosing scope.
819 is actually the same as
828 This is the reason why a procedure must have a name. If you want a scope
829 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
831 <bf/Note:/ As you can see from the example above, scopes and symbols live in
832 different namespaces. There can be a symbol named <tt/foo/ and a scope named
833 <tt/foo/ without any conflicts (but see the section titled <ref
834 id="scopesearch" name=""Scope search order"">).
837 <sect1>Structs, unions and enums<p>
839 Structs, unions and enums are explained in a <ref id="structs" name="separate
840 section">, I do only cover them here, because if they are declared with a
841 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
842 name=".SCOPE">/. However, when no name is specified, the behaviour is
843 different: In this case, no new scope will be opened, symbols declared within
844 a struct, union, or enum declaration will then be added to the enclosing scope
848 <sect1>Explicit scope specification<label id="scopesyntax"><p>
850 Accessing symbols from other scopes is possible by using an explicit scope
851 specification, provided that the scope where the symbol lives in has a name.
852 The namespace token (<tt/::/) is used to access other scopes:
860 lda foo::bar ; Access foo in scope bar
863 The only way to deny access to a scope from the outside is to declare a scope
864 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
866 A special syntax is used to specify the global scope: If a symbol or scope is
867 preceded by the namespace token, the global scope is searched:
874 lda #::bar ; Access the global bar (which is 3)
879 <sect1>Scope search order<label id="scopesearch"><p>
881 The assembler searches for a scope in a similar way as for a symbol. First, it
882 looks in the current scope, and then it walks up the enclosing scopes until
885 However, one important thing to note when using explicit scope syntax is, that
886 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
887 used without a preceding definition. This means that in the following
896 lda #foo::bar ; Will load 3, not 2!
903 the reference to the scope <tt/foo/ will use the global scope, and not the
904 local one, because the local one is not visible at the point where it is
907 Things get more complex if a complete chain of scopes is specified:
918 lda #outer::inner::bar ; 1
930 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
931 assembler will first search in the local scope for a scope named <tt/outer/.
932 Since none is found, the enclosing scope (<tt/another/) is checked. There is
933 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
934 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
935 this scope, the assembler looks for a symbol named <tt/bar/.
937 Please note that once the anchor scope is found, all following scopes
938 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
939 assembler will search the scope tree only for the first scope (if it is not
940 anchored in the root scope). Starting from there on, there is no flexibility,
941 so if the scope named <tt/outer/ found by the assembler does not contain a
942 scope named <tt/inner/, this would be an error, even if such a pair does exist
943 (one level up in global scope).
945 Ambiguities that may be introduced by this search algorithm may be removed by
946 anchoring the scope specification in the global scope. In the example above,
947 if you want to access the "other" symbol <tt/bar/, you would have to write:
958 lda #::outer::inner::bar ; 2
971 <sect>Address sizes and memory models<label id="address-sizes"><p>
973 <sect1>Address sizes<p>
975 ca65 assigns each segment and each symbol an address size. This is true, even
976 if the symbol is not used as an address. You may also think of a value range
977 of the symbol instead of an address size.
979 Possible address sizes are:
982 <item>Zeropage or direct (8 bits)
983 <item>Absolute (16 bits)
988 Since the assembler uses default address sizes for the segments and symbols,
989 it is usually not necessary to override the default behaviour. In cases, where
990 it is necessary, the following keywords may be used to specify address sizes:
993 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
994 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
995 <item>FAR for far addressing (24 bits).
996 <item>LONG or DWORD for long addressing (32 bits).
1000 <sect1>Address sizes of segments<p>
1002 The assembler assigns an address size to each segment. Since the
1003 representation of a label within this segment is "segment start + offset",
1004 labels will inherit the address size of the segment they are declared in.
1006 The address size of a segment may be changed, by using an optional address
1007 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1008 an explanation on how this is done.
1011 <sect1>Address sizes of symbols<p>
1016 <sect1>Memory models<p>
1018 The default address size of a segment depends on the memory model used. Since
1019 labels inherit the address size from the segment they are declared in,
1020 changing the memory model is an easy way to change the address size of many
1026 <sect>Pseudo variables<label id="pseudo-variables"><p>
1028 Pseudo variables are readable in all cases, and in some special cases also
1031 <sect1><tt>*</tt><p>
1033 Reading this pseudo variable will return the program counter at the start
1034 of the current input line.
1036 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1037 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1038 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1041 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1043 Reading this pseudo variable will give a constant integer value that
1044 tells which CPU is currently enabled. It can also tell which instruction
1045 set the CPU is able to translate. The value read from the pseudo variable
1046 should be further examined by using one of the constants defined by the
1047 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1049 It may be used to replace the .IFPxx pseudo instructions or to construct
1050 even more complex expressions.
1056 .if (.cpu .bitand CPU_ISET_65816)
1068 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1070 This builtin pseudo variable is only available in macros. It is replaced by
1071 the actual number of parameters that were given in the macro invocation.
1076 .macro foo arg1, arg2, arg3
1077 .if .paramcount <> 3
1078 .error "Too few parameters for macro foo"
1084 See section <ref id="macros" name="Macros">.
1087 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1089 Reading this pseudo variable will give a constant integer value that
1090 represents the current time in POSIX standard (as seconds since the
1093 It may be used to encode the time of translation somewhere in the created
1099 .dword .time ; Place time here
1103 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1105 Reading this pseudo variable will give the assembler version according to
1106 the following formula:
1108 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1110 It may be used to encode the assembler version or check the assembler for
1111 special features not available with older versions.
1115 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1116 reading the pseudo variable <tt/.VERSION/.
1120 <sect>Pseudo functions<label id="pseudo-functions"><p>
1122 Pseudo functions expect their arguments in parenthesis, and they have a result,
1123 either a string or an expression.
1126 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1128 The function returns the bank byte (that is, bits 16-23) of its argument.
1129 It works identical to the '^' operator.
1131 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1132 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1135 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1137 Builtin function. The function evaluates its argument in braces and yields
1138 "false" if the argument is non blank (there is an argument), and "true" if
1139 there is no argument. The token list that makes up the function argument
1140 may optionally be enclosed in curly braces. This allows the inclusion of
1141 tokens that would otherwise terminate the list (the closing right
1142 parenthesis). The curly braces are not considered part of the list, a list
1143 just consisting of curly braces is considered to be empty.
1145 As an example, the <tt/.IFBLANK/ statement may be replaced by
1153 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1155 Builtin string function. The function allows to concatenate a list of string
1156 constants separated by commas. The result is a string constant that is the
1157 concatenation of all arguments. This function is most useful in macros and
1158 when used together with the <tt/.STRING/ builtin function. The function may
1159 be used in any case where a string constant is expected.
1164 .include .concat ("myheader", ".", "inc")
1167 This is the same as the command
1170 .include "myheader.inc"
1174 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1176 Builtin function. The function evaluates its argument in braces and
1177 yields "true" if the argument is a constant expression (that is, an
1178 expression that yields a constant value at assembly time) and "false"
1179 otherwise. As an example, the .IFCONST statement may be replaced by
1186 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1188 The function returns the high byte (that is, bits 8-15) of its argument.
1189 It works identical to the '>' operator.
1191 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1192 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1195 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1197 The function returns the high word (that is, bits 16-31) of its argument.
1199 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1202 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1204 The function expects a string as its argument, and converts this argument
1205 into an identifier. If the string starts with the current <tt/<ref
1206 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1207 identifier, otherwise it will be converted into a normal identifier.
1212 .macro makelabel arg1, arg2
1213 .ident (.concat (arg1, arg2)):
1216 makelabel "foo", "bar"
1218 .word foobar ; Valid label
1222 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1224 Builtin function. Extracts the left part of a given token list.
1229 .LEFT (<int expr>, <token list>)
1232 The first integer expression gives the number of tokens to extract from
1233 the token list. The second argument is the token list itself. The token
1234 list may optionally be enclosed into curly braces. This allows the
1235 inclusion of tokens that would otherwise terminate the list (the closing
1236 right paren in the given case).
1240 To check in a macro if the given argument has a '#' as first token
1241 (immediate addressing mode), use something like this:
1246 .if (.match (.left (1, {arg}), #))
1248 ; ldax called with immediate operand
1256 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1257 name=".RIGHT"></tt> builtin functions.
1260 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1262 The function returns the low byte (that is, bits 0-7) of its argument.
1263 It works identical to the '<' operator.
1265 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1266 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1269 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1271 The function returns the low word (that is, bits 0-15) of its argument.
1273 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1276 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1278 Builtin function. Matches two token lists against each other. This is
1279 most useful within macros, since macros are not stored as strings, but
1285 .MATCH(<token list #1>, <token list #2>)
1288 Both token list may contain arbitrary tokens with the exception of the
1289 terminator token (comma resp. right parenthesis) and
1296 The token lists may optionally be enclosed into curly braces. This allows
1297 the inclusion of tokens that would otherwise terminate the list (the closing
1298 right paren in the given case). Often a macro parameter is used for any of
1301 Please note that the function does only compare tokens, not token
1302 attributes. So any number is equal to any other number, regardless of the
1303 actual value. The same is true for strings. If you need to compare tokens
1304 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1305 name=".XMATCH"></tt> function.
1309 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1310 while honoring the sign bit. The builtin processor instructions will allow
1311 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1312 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1313 to check for this and print and error for invalid calls.
1318 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1319 .error "Syntax error"
1322 cmp #$80 ; Bit 7 into carry
1323 lsr a ; Shift carry into bit 7
1328 The macro will only accept no arguments, or one argument that must be the
1329 reserved keyword "A".
1331 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1334 <sect1><tt>.MID</tt><label id=".MID"><p>
1336 Builtin function. Takes a starting index, a count and a token list as
1337 arguments. Will return part of the token list.
1342 .MID (<int expr>, <int expr>, <token list>)
1345 The first integer expression gives the starting token in the list (the first
1346 token has index 0). The second integer expression gives the number of tokens
1347 to extract from the token list. The third argument is the token list itself.
1348 The token list may optionally be enclosed into curly braces. This allows the
1349 inclusion of tokens that would otherwise terminate the list (the closing
1350 right paren in the given case).
1354 To check in a macro if the given argument has a '<tt/#/' as first token
1355 (immediate addressing mode), use something like this:
1360 .if (.match (.mid (0, 1, {arg}), #))
1362 ; ldax called with immediate operand
1370 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1371 name=".RIGHT"></tt> builtin functions.
1374 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1376 Builtin function. The function expects an identifier as argument in braces.
1377 The argument is evaluated, and the function yields "true" if the identifier
1378 is a symbol that has already been referenced somewhere in the source file up
1379 to the current position. Otherwise the function yields false. As an example,
1380 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1386 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1389 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1391 Builtin function. Extracts the right part of a given token list.
1396 .RIGHT (<int expr>, <token list>)
1399 The first integer expression gives the number of tokens to extract from the
1400 token list. The second argument is the token list itself. The token list
1401 may optionally be enclosed into curly braces. This allows the inclusion of
1402 tokens that would otherwise terminate the list (the closing right paren in
1405 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1406 name=".MID"></tt> builtin functions.
1409 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1411 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1412 argument can be a struct/union, a struct member, a procedure, or a label. In
1413 case of a procedure or label, its size is defined by the amount of data
1414 placed in the segment where the label is relative to. If a line of code
1415 switches segments (for example in a macro) data placed in other segments
1416 does not count for the size.
1418 Please note that a symbol or scope must exist, before it is used together with
1419 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1420 A scope has preference over a symbol with the same name, so if the last part
1421 of a name represents both, a scope and a symbol, the scope is chosen over the
1424 After the following code:
1427 .struct Point ; Struct size = 4
1432 P: .tag Point ; Declare a point
1433 @P: .tag Point ; Declare another point
1445 .data ; Segment switch!!!
1451 <tag><tt/.sizeof(Point)/</tag>
1452 will have the value 4, because this is the size of struct <tt/Point/.
1454 <tag><tt/.sizeof(Point::xcoord)/</tag>
1455 will have the value 2, because this is the size of the member <tt/xcoord/
1456 in struct <tt/Point/.
1458 <tag><tt/.sizeof(P)/</tag>
1459 will have the value 4, this is the size of the data declared on the same
1460 source line as the label <tt/P/, which is in the same segment that <tt/P/
1463 <tag><tt/.sizeof(@P)/</tag>
1464 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1465 does also work for cheap local symbols.
1467 <tag><tt/.sizeof(Code)/</tag>
1468 will have the value 3, since this is amount of data emitted into the code
1469 segment, the segment that was active when <tt/Code/ was entered. Note that
1470 this value includes the amount of data emitted in child scopes (in this
1471 case <tt/Code::Inner/).
1473 <tag><tt/.sizeof(Code::Inner)/</tag>
1474 will have the value 1 as expected.
1476 <tag><tt/.sizeof(Data)/</tag>
1477 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1478 the segment is switched after entry, this data is emitted into another
1483 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1485 Builtin function. The function accepts a string and an index as
1486 arguments and returns the value of the character at the given position
1487 as an integer value. The index is zero based.
1493 ; Check if the argument string starts with '#'
1494 .if (.strat (Arg, 0) = '#')
1501 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1503 Builtin function. It expects a format string as first argument. The number
1504 and type of the following arguments depend on the format string. The format
1505 string is similar to the one of the C <tt/printf/ function. Missing things
1506 are: Length modifiers, variable width.
1508 The result of the function is a string.
1515 ; Generate an identifier:
1516 .ident (.sprintf ("%s%03d", "label", num)):
1520 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1522 Builtin function. The function accepts an argument in braces and converts
1523 this argument into a string constant. The argument may be an identifier, or
1524 a constant numeric value.
1526 Since you can use a string in the first place, the use of the function may
1527 not be obvious. However, it is useful in macros, or more complex setups.
1532 ; Emulate other assemblers:
1534 .segment .string(name)
1539 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1541 Builtin function. The function accepts a string argument in braces and
1542 evaluates to the length of the string.
1546 The following macro encodes a string as a pascal style string with
1547 a leading length byte.
1551 .byte .strlen(Arg), Arg
1556 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1558 Builtin function. The function accepts a token list in braces. The function
1559 result is the number of tokens given as argument. The token list may
1560 optionally be enclosed into curly braces which are not considered part of
1561 the list and not counted. Enclosement in curly braces allows the inclusion
1562 of tokens that would otherwise terminate the list (the closing right paren
1567 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1568 with the normal 6502 instructions). To translate it into two separate 8 bit
1569 load instructions, the '#' token has to get stripped from the argument:
1573 .if (.match (.mid (0, 1, {arg}), #))
1574 ; ldax called with immediate operand
1575 lda #<(.right (.tcount ({arg})-1, {arg}))
1576 ldx #>(.right (.tcount ({arg})-1, {arg}))
1584 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1586 Builtin function. Matches two token lists against each other. This is
1587 most useful within macros, since macros are not stored as strings, but
1593 .XMATCH(<token list #1>, <token list #2>)
1596 Both token list may contain arbitrary tokens with the exception of the
1597 terminator token (comma resp. right parenthesis) and
1604 The token lists may optionally be enclosed into curly braces. This allows
1605 the inclusion of tokens that would otherwise terminate the list (the closing
1606 right paren in the given case). Often a macro parameter is used for any of
1609 The function compares tokens <em/and/ token values. If you need a function
1610 that just compares the type of tokens, have a look at the <tt><ref
1611 id=".MATCH" name=".MATCH"></tt> function.
1613 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1617 <sect>Control commands<label id="control-commands"><p>
1619 Here's a list of all control commands and a description, what they do:
1622 <sect1><tt>.A16</tt><label id=".A16"><p>
1624 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1626 Note: This command will not emit any code, it will tell the assembler to
1627 create 16 bit operands for immediate accumulator addressing mode.
1629 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1632 <sect1><tt>.A8</tt><label id=".A8"><p>
1634 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1636 Note: This command will not emit any code, it will tell the assembler to
1637 create 8 bit operands for immediate accu addressing mode.
1639 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1642 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1644 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1645 may be used for better readability if the data words are address values. In
1646 65816 mode, the address is forced to be 16 bit wide to fit into the current
1647 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1648 must be followed by a sequence of (not necessarily constant) expressions.
1653 .addr $0D00, $AF13, _Clear
1656 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1660 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1662 Align data to a given boundary. The command expects a constant integer
1663 argument that must be a power of two, plus an optional second argument
1664 in byte range. If there is a second argument, it is used as fill value,
1665 otherwise the value defined in the linker configuration file is used
1666 (the default for this value is zero).
1668 Since alignment depends on the base address of the module, you must
1669 give the same (or a greater) alignment for the segment when linking.
1670 The linker will give you a warning, if you don't do that.
1679 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1681 Define a string with a trailing zero.
1686 Msg: .asciiz "Hello world"
1689 This will put the string "Hello world" followed by a binary zero into
1690 the current segment. There may be more strings separated by commas, but
1691 the binary zero is only appended once (after the last one).
1694 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1696 Add an assertion. The command is followed by an expression, an action
1697 specifier, and an optional message that is output in case the assertion
1698 fails. If no message was given, the string "Assertion failed" is used. The
1699 action specifier may be one of <tt/warning/ or <tt/error/. The assertion is
1700 evaluated by the assembler if possible, and also passed to the linker in the
1701 object file (if one is generated). The linker will then evaluate the
1702 expression when segment placement has been done.
1707 .assert * = $8000, error, "Code not at $8000"
1710 The example assertion will check that the current location is at $8000,
1711 when the output file is written, and abort with an error if this is not
1712 the case. More complex expressions are possible. The action specifier
1713 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1714 an error message. In the latter case, generation if the output file is
1715 suppressed in both the assembler and linker.
1718 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1720 Is followed by a plus or a minus character. When switched on (using a
1721 +), undefined symbols are automatically marked as import instead of
1722 giving errors. When switched off (which is the default so this does not
1723 make much sense), this does not happen and an error message is
1724 displayed. The state of the autoimport flag is evaluated when the
1725 complete source was translated, before outputting actual code, so it is
1726 <em/not/ possible to switch this feature on or off for separate sections
1727 of code. The last setting is used for all symbols.
1729 You should probably not use this switch because it delays error
1730 messages about undefined symbols until the link stage. The cc65
1731 compiler (which is supposed to produce correct assembler code in all
1732 circumstances, something which is not true for most assembler
1733 programmers) will insert this command to avoid importing each and every
1734 routine from the runtime library.
1739 .autoimport + ; Switch on auto import
1743 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1745 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1746 so this is a shortcut for
1752 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1755 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1757 Define byte sized data. Must be followed by a sequence of (byte ranged)
1758 expressions or strings.
1764 .byt "world", $0D, $00
1768 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1770 Switch on or off case sensitivity on identifiers. The default is off
1771 (that is, identifiers are case sensitive), but may be changed by the
1772 -i switch on the command line.
1773 The command must be followed by a '+' or '-' character to switch the
1774 option on or off respectively.
1779 .case - ; Identifiers are not case sensitive
1783 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1785 Apply a custom mapping for characters. The command is followed by two
1786 numbers in the range 1..255. The first one is the index of the source
1787 character, the second one is the mapping. The mapping applies to all
1788 character and string constants when they generate output, and overrides
1789 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1790 command line switch.
1795 .charmap $41, $61 ; Map 'A' to 'a'
1799 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1801 Switch to the CODE segment. The name of the CODE segment is always
1802 "CODE", so this is a shortcut for
1808 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1811 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1813 Export a symbol and mark it in a special way. The linker is able to build
1814 tables of all such symbols. This may be used to automatically create a list
1815 of functions needed to initialize linked library modules.
1817 Note: The linker has a feature to build a table of marked routines, but it
1818 is your code that must call these routines, so just declaring a symbol with
1819 <tt/.CONDES/ does nothing by itself.
1821 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1822 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1823 is implied by <tt/.CONDES/.
1825 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1826 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1827 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1828 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1829 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1830 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
1831 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
1833 After the type, an optional priority may be specified. Higher numeric values
1834 mean higher priority. If no priority is given, the default priority of 7 is
1835 used. Be careful when assigning priorities to your own module constructors
1836 so they won't interfere with the ones in the cc65 library.
1841 .condes ModuleInit, constructor
1842 .condes ModInit, 0, 16
1845 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1846 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1847 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
1848 name="Module constructors/destructors"> explaining the feature in more
1852 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1854 Export a symbol and mark it as a module constructor. This may be used
1855 together with the linker to build a table of constructor subroutines that
1856 are called by the startup code.
1858 Note: The linker has a feature to build a table of marked routines, but it
1859 is your code that must call these routines, so just declaring a symbol as
1860 constructor does nothing by itself.
1862 A constructor is always exported as an absolute (16 bit) symbol. You don't
1863 need to use an additional <tt/.export/ statement, this is implied by
1864 <tt/.constructor/. It may have an optional priority that is separated by a
1865 comma. Higher numeric values mean a higher priority. If no priority is
1866 given, the default priority of 7 is used. Be careful when assigning
1867 priorities to your own module constructors so they won't interfere with the
1868 ones in the cc65 library.
1873 .constructor ModuleInit
1874 .constructor ModInit, 16
1877 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1878 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1879 <ref id="condes" name="Module constructors/destructors"> explaining the
1880 feature in more detail.
1883 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1885 Switch to the DATA segment. The name of the DATA segment is always
1886 "DATA", so this is a shortcut for
1892 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1895 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1897 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1898 create word sized data in native 65XX format). Must be followed by a
1899 sequence of (word ranged) expressions.
1907 This will emit the bytes
1913 into the current segment in that order.
1916 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1918 Switch on or off debug info generation. The default is off (that is,
1919 the object file will not contain debug infos), but may be changed by the
1920 -g switch on the command line.
1921 The command must be followed by a '+' or '-' character to switch the
1922 option on or off respectively.
1927 .debuginfo + ; Generate debug info
1931 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
1933 Start a define style macro definition. The command is followed by an
1934 identifier (the macro name) and optionally by a list of formal arguments
1936 See section <ref id="macros" name="Macros">.
1939 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
1941 Builtin function. The function expects an identifier as argument in braces.
1942 The argument is evaluated, and the function yields "true" if the identifier
1943 is a symbol that is already defined somewhere in the source file up to the
1944 current position. Otherwise the function yields false. As an example, the
1945 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
1952 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
1954 Export a symbol and mark it as a module destructor. This may be used
1955 together with the linker to build a table of destructor subroutines that
1956 are called by the startup code.
1958 Note: The linker has a feature to build a table of marked routines, but it
1959 is your code that must call these routines, so just declaring a symbol as
1960 constructor does nothing by itself.
1962 A destructor is always exported as an absolute (16 bit) symbol. You don't
1963 need to use an additional <tt/.export/ statement, this is implied by
1964 <tt/.destructor/. It may have an optional priority that is separated by a
1965 comma. Higher numerical values mean a higher priority. If no priority is
1966 given, the default priority of 7 is used. Be careful when assigning
1967 priorities to your own module destructors so they won't interfere with the
1968 ones in the cc65 library.
1973 .destructor ModuleDone
1974 .destructor ModDone, 16
1977 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1978 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
1979 section <ref id="condes" name="Module constructors/destructors"> explaining
1980 the feature in more detail.
1983 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
1985 Define dword sized data (4 bytes) Must be followed by a sequence of
1991 .dword $12344512, $12FA489
1995 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
1997 Conditional assembly: Reverse the current condition.
2000 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2002 Conditional assembly: Reverse current condition and test a new one.
2005 <sect1><tt>.END</tt><label id=".END"><p>
2007 Forced end of assembly. Assembly stops at this point, even if the command
2008 is read from an include file.
2011 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2013 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2016 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2018 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2019 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2022 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2024 End of macro definition (see section <ref id="macros" name="Macros">).
2027 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2029 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2032 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2034 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2037 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2039 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2042 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2044 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2045 command and the separate section named <ref id="structs" name=""Structs
2049 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2051 Start an enumeration. This directive is very similar to the C <tt/enum/
2052 keyword. If a name is given, a new scope is created for the enumeration,
2053 otherwise the enumeration members are placed in the enclosing scope.
2055 In the enumeration body, symbols are declared. The first symbol has a value
2056 of zero, and each following symbol will get the value of the preceding plus
2057 one. This behaviour may be overridden by an explicit assignment. Two symbols
2058 may have the same value.
2070 Above example will create a new scope named <tt/errorcodes/ with three
2071 symbols in it that get the values 0, 1 and 2 respectively. Another way
2072 to write this would have been:
2082 Please note that explicit scoping must be used to access the identifiers:
2085 .word errorcodes::no_error
2088 A more complex example:
2097 EWOULDBLOCK = EAGAIN
2101 In this example, the enumeration does not have a name, which means that the
2102 members will be visible in the enclosing scope and can be used in this scope
2103 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2104 The value for the following members is incremented by one, so <tt/EOK/ would
2105 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2106 override for the value using an already defined symbol.
2109 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2111 Force an assembly error. The assembler will output an error message
2112 preceded by "User error" and will <em/not/ produce an object file.
2114 This command may be used to check for initial conditions that must be
2115 set before assembling a source file.
2125 .error "Must define foo or bar!"
2129 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2130 id=".OUT" name=".OUT"></tt> directives.
2133 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2135 Abort a macro expansion immediately. This command is often useful in
2136 recursive macros. See separate section <ref id="macros" name="Macros">.
2139 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2141 Make symbols accessible from other modules. Must be followed by a comma
2142 separated list of symbols to export, with each one optionally followed by
2143 an address specification. The default is to export the symbol with the
2144 address size it actually has. The assembler will issue a warning, if the
2145 symbol is exported with an address size smaller than the actual address
2155 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2158 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2160 Make symbols accessible from other modules. Must be followed by a comma
2161 separated list of symbols to export. The exported symbols are explicitly
2162 marked as zero page symbols.
2170 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2173 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2175 Define far (24 bit) address data. The command must be followed by a
2176 sequence of (not necessarily constant) expressions.
2181 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2184 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2187 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2189 This directive may be used to enable one or more compatibility features
2190 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2191 possible, it may be useful when porting sources written for other
2192 assemblers. There is no way to switch a feature off, once you have
2193 enabled it, so using
2199 will enable the feature until end of assembly is reached.
2201 The following features are available:
2205 <tag><tt>at_in_identifiers</tt></tag>
2207 Accept the at character (`@') as a valid character in identifiers. The
2208 at character is not allowed to start an identifier, even with this
2211 <tag><tt>dollar_in_identifiers</tt></tag>
2213 Accept the dollar sign (`$') as a valid character in identifiers. The
2214 at character is not allowed to start an identifier, even with this
2217 <tag><tt>dollar_is_pc</tt></tag>
2219 The dollar sign may be used as an alias for the star (`*'), which
2220 gives the value of the current PC in expressions.
2221 Note: Assignment to the pseudo variable is not allowed.
2223 <tag><tt>labels_without_colons</tt></tag>
2225 Allow labels without a trailing colon. These labels are only accepted,
2226 if they start at the beginning of a line (no leading white space).
2228 <tag><tt>leading_dot_in_identifiers</tt></tag>
2230 Accept the dot (`.') as the first character of an identifier. This may be
2231 used for example to create macro names that start with a dot emulating
2232 control directives of other assemblers. Note however, that none of the
2233 reserved keywords built into the assembler, that starts with a dot, may be
2234 overridden. When using this feature, you may also get into trouble if
2235 later versions of the assembler define new keywords starting with a dot.
2237 <tag><tt>loose_char_term</tt></tag>
2239 Accept single quotes as well as double quotes as terminators for char
2242 <tag><tt>loose_string_term</tt></tag>
2244 Accept single quotes as well as double quotes as terminators for string
2247 <tag><tt>missing_char_term</tt></tag>
2249 Accept single quoted character constants where the terminating quote is
2254 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2255 loose_string_term/, since in this case the input would be ambiguous.
2257 <tag><tt>pc_assignment</tt></tag>
2259 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2260 is enabled). Such an assignment is handled identical to the <tt><ref
2261 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2262 removing the lines with the assignments may also be an option when porting
2263 code written for older assemblers).
2265 <tag><tt>ubiquitous_idents</tt></tag>
2267 Allow the use of instructions names as names for macros and symbols. This
2268 makes it possible to "overload" instructions by defining a macro with the
2269 same name. This does also make it possible to introduce hard to find errors
2270 in your code, so be careful!
2274 It is also possible to specify features on the command line using the
2275 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2276 This is useful when translating sources written for older assemblers, when
2277 you don't want to change the source code.
2279 As an example, to translate sources written for Andre Fachats xa65
2280 assembler, the features
2283 labels_without_colons, pc_assignment, loose_char_term
2286 may be helpful. They do not make ca65 completely compatible, so you may not
2287 be able to translate the sources without changes, even when enabling these
2288 features. However, I have found several sources that translate without
2289 problems when enabling these features on the command line.
2292 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2294 Insert an option string into the object file. There are two forms of
2295 this command, one specifies the option by a keyword, the second
2296 specifies it as a number. Since usage of the second one needs knowledge
2297 of the internal encoding, its use is not recommended and I will only
2298 describe the first form here.
2300 The command is followed by one of the keywords
2308 a comma and a string. The option is written into the object file
2309 together with the string value. This is currently unidirectional and
2310 there is no way to actually use these options once they are in the
2316 .fileopt comment, "Code stolen from my brother"
2317 .fileopt compiler, "BASIC 2.0"
2318 .fopt author, "J. R. User"
2322 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2324 Import an absolute symbol from another module. The command is followed by a
2325 comma separated list of symbols to import. The command is similar to <tt>
2326 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2327 written to the generated object file, even if the symbol is never referenced
2328 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2329 references for unused symbols).
2334 .forceimport needthisone, needthistoo
2337 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2340 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2342 Declare symbols as global. Must be followed by a comma separated list of
2343 symbols to declare. Symbols from the list, that are defined somewhere in the
2344 source, are exported, all others are imported. Additional <tt><ref
2345 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2346 name=".EXPORT"></tt> commands for the same symbol are allowed.
2355 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2357 Declare symbols as global. Must be followed by a comma separated list of
2358 symbols to declare. Symbols from the list, that are defined somewhere in the
2359 source, are exported, all others are imported. Additional <tt><ref
2360 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2361 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2362 in the list are explicitly marked as zero page symbols.
2371 <sect1><tt>.I16</tt><label id=".I16"><p>
2373 Valid only in 65816 mode. Switch the index registers to 16 bit.
2375 Note: This command will not emit any code, it will tell the assembler to
2376 create 16 bit operands for immediate operands.
2378 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2379 name=".SMART"></tt> commands.
2382 <sect1><tt>.I8</tt><label id=".I8"><p>
2384 Valid only in 65816 mode. Switch the index registers to 8 bit.
2386 Note: This command will not emit any code, it will tell the assembler to
2387 create 8 bit operands for immediate operands.
2389 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2390 name=".SMART"></tt> commands.
2393 <sect1><tt>.IF</tt><label id=".IF"><p>
2395 Conditional assembly: Evaluate an expression and switch assembler output
2396 on or off depending on the expression. The expression must be a constant
2397 expression, that is, all operands must be defined.
2399 A expression value of zero evaluates to FALSE, any other value evaluates
2403 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2405 Conditional assembly: Check if there are any remaining tokens in this line,
2406 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2407 condition is not true, further lines are not assembled until an <tt><ref
2408 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2409 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2411 This command is often used to check if a macro parameter was given. Since an
2412 empty macro parameter will evaluate to nothing, the condition will evaluate
2413 to FALSE if an empty parameter was given.
2427 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2430 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2432 Conditional assembly: Evaluate an expression and switch assembler output
2433 on or off depending on the constness of the expression.
2435 A const expression evaluates to to TRUE, a non const expression (one
2436 containing an imported or currently undefined symbol) evaluates to
2439 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2442 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2444 Conditional assembly: Check if a symbol is defined. Must be followed by
2445 a symbol name. The condition is true if the the given symbol is already
2446 defined, and false otherwise.
2448 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2451 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2453 Conditional assembly: Check if there are any remaining tokens in this line,
2454 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2455 condition is not true, further lines are not assembled until an <tt><ref
2456 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2457 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2459 This command is often used to check if a macro parameter was given.
2460 Since an empty macro parameter will evaluate to nothing, the condition
2461 will evaluate to FALSE if an empty parameter was given.
2474 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2477 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2479 Conditional assembly: Check if a symbol is defined. Must be followed by
2480 a symbol name. The condition is true if the the given symbol is not
2481 defined, and false otherwise.
2483 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2486 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2488 Conditional assembly: Check if a symbol is referenced. Must be followed
2489 by a symbol name. The condition is true if if the the given symbol was
2490 not referenced before, and false otherwise.
2492 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2495 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2497 Conditional assembly: Check if the assembler is currently in 6502 mode
2498 (see <tt><ref id=".P02" name=".P02"></tt> command).
2501 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2503 Conditional assembly: Check if the assembler is currently in 65816 mode
2504 (see <tt><ref id=".P816" name=".P816"></tt> command).
2507 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2509 Conditional assembly: Check if the assembler is currently in 65C02 mode
2510 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2513 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2515 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2516 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2519 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2521 Conditional assembly: Check if a symbol is referenced. Must be followed
2522 by a symbol name. The condition is true if if the the given symbol was
2523 referenced before, and false otherwise.
2525 This command may be used to build subroutine libraries in include files
2526 (you may use separate object modules for this purpose too).
2531 .ifref ToHex ; If someone used this subroutine
2532 ToHex: tay ; Define subroutine
2538 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2541 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2543 Import a symbol from another module. The command is followed by a comma
2544 separated list of symbols to import, with each one optionally followed by
2545 an address specification.
2551 .import bar: zeropage
2554 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2557 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2559 Import a symbol from another module. The command is followed by a comma
2560 separated list of symbols to import. The symbols are explicitly imported
2561 as zero page symbols (that is, symbols with values in byte range).
2569 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2572 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2574 Include a file as binary data. The command expects a string argument
2575 that is the name of a file to include literally in the current segment.
2576 In addition to that, a start offset and a size value may be specified,
2577 separated by commas. If no size is specified, all of the file from the
2578 start offset to end-of-file is used. If no start position is specified
2579 either, zero is assumed (which means that the whole file is inserted).
2584 ; Include whole file
2585 .incbin "sprites.dat"
2587 ; Include file starting at offset 256
2588 .incbin "music.dat", $100
2590 ; Read 100 bytes starting at offset 200
2591 .incbin "graphics.dat", 200, 100
2595 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2597 Include another file. Include files may be nested up to a depth of 16.
2606 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
2608 Export a symbol and mark it as an interruptor. This may be used together
2609 with the linker to build a table of interruptor subroutines that are called
2612 Note: The linker has a feature to build a table of marked routines, but it
2613 is your code that must call these routines, so just declaring a symbol as
2614 interruptor does nothing by itself.
2616 An interruptor is always exported as an absolute (16 bit) symbol. You don't
2617 need to use an additional <tt/.export/ statement, this is implied by
2618 <tt/.interruptor/. It may have an optional priority that is separated by a
2619 comma. Higher numeric values mean a higher priority. If no priority is
2620 given, the default priority of 7 is used. Be careful when assigning
2621 priorities to your own module constructors so they won't interfere with the
2622 ones in the cc65 library.
2627 .interruptor IrqHandler
2628 .interruptor Handler, 16
2631 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
2632 section <ref id="condes" name="Module constructors/destructors"> explaining
2633 the feature in more detail.
2636 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2638 Switch on or off line continuations using the backslash character
2639 before a newline. The option is off by default.
2640 Note: Line continuations do not work in a comment. A backslash at the
2641 end of a comment is treated as part of the comment and does not trigger
2643 The command must be followed by a '+' or '-' character to switch the
2644 option on or off respectively.
2649 .linecont + ; Allow line continuations
2652 #$20 ; This is legal now
2656 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2658 Enable output to the listing. The command must be followed by a boolean
2659 switch ("on", "off", "+" or "-") and will enable or disable listing
2661 The option has no effect if the listing is not enabled by the command line
2662 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2663 to the listing file, if the counter is greater than zero, and suppressed if
2664 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2670 .list on ; Enable listing output
2674 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2676 Set, how many bytes are shown in the listing for one source line. The
2677 default is 12, so the listing will show only the first 12 bytes for any
2678 source line that generates more than 12 bytes of code or data.
2679 The directive needs an argument, which is either "unlimited", or an
2680 integer constant in the range 4..255.
2685 .listbytes unlimited ; List all bytes
2686 .listbytes 12 ; List the first 12 bytes
2687 .incbin "data.bin" ; Include large binary file
2691 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2693 This command may only be used inside a macro definition. It declares a
2694 list of identifiers as local to the macro expansion.
2696 A problem when using macros are labels: Since they don't change their name,
2697 you get a "duplicate symbol" error if the macro is expanded the second time.
2698 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2699 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2702 Some other assemblers start a new lexical block inside a macro expansion.
2703 This has some drawbacks however, since that will not allow <em/any/ symbol
2704 to be visible outside a macro, a feature that is sometimes useful. The
2705 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2706 to address the problem.
2708 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2712 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2714 Defines the character that start "cheap" local labels. You may use one
2715 of '@' and '?' as start character. The default is '@'.
2717 Cheap local labels are labels that are visible only between two non
2718 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2719 using explicit lexical nesting.
2726 Clear: lda #$00 ; Global label
2727 ?Loop: sta Mem,y ; Local label
2731 Sub: ... ; New global label
2732 bne ?Loop ; ERROR: Unknown identifier!
2736 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2738 Insert a predefined macro package. The command is followed by an
2739 identifier specifying the macro package to insert. Available macro
2743 generic Defines generic macros like add and sub.
2744 longbranch Defines conditional long jump macros.
2745 cbm Defines the scrcode macro
2746 cpu Defines constants for the .CPU variable
2749 Including a macro package twice, or including a macro package that
2750 redefines already existing macros will lead to an error.
2755 .macpack longbranch ; Include macro package
2757 cmp #$20 ; Set condition codes
2758 jne Label ; Jump long on condition
2761 Macro packages are explained in more detail in section <ref
2762 id="macropackages" name="Macro packages">.
2765 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2767 Start a classic macro definition. The command is followed by an identifier
2768 (the macro name) and optionally by a comma separated list of identifiers
2769 that are macro parameters.
2771 See section <ref id="macros" name="Macros">.
2774 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2776 Start a section of absolute code. The command is followed by a constant
2777 expression that gives the new PC counter location for which the code is
2778 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2781 Please note that you <em/do not need/ this command in most cases. Placing
2782 code at a specific address is the job of the linker, not the assembler, so
2783 there is usually no reason to assemble code to a specific address.
2785 You may not switch segments while inside a section of absolute code.
2790 .org $7FF ; Emit code starting at $7FF
2794 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2796 Output a string to the console without producing an error. This command
2797 is similar to <tt/.ERROR/, however, it does not force an assembler error
2798 that prevents the creation of an object file.
2803 .out "This code was written by the codebuster(tm)"
2806 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2807 id=".ERROR" name=".ERROR"></tt> directives.
2810 <sect1><tt>.P02</tt><label id=".P02"><p>
2812 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
2813 instructions. This is the default if not overridden by the
2814 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
2816 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
2817 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2820 <sect1><tt>.P816</tt><label id=".P816"><p>
2822 Enable the 65816 instruction set. This is a superset of the 65SC02 and
2823 6502 instruction sets.
2825 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2826 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
2829 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
2831 Set the page length for the listing. Must be followed by an integer
2832 constant. The value may be "unlimited", or in the range 32 to 127. The
2833 statement has no effect if no listing is generated. The default value is -1
2834 (unlimited) but may be overridden by the <tt/--pagelength/ command line
2835 option. Beware: Since ca65 is a one pass assembler, the listing is generated
2836 after assembly is complete, you cannot use multiple line lengths with one
2837 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
2842 .pagelength 66 ; Use 66 lines per listing page
2844 .pagelength unlimited ; Unlimited page length
2848 <sect1><tt>.PC02</tt><label id=".PC02"><p>
2850 Enable the 65C02 instructions set. This instruction set includes all
2851 6502 and 65SC02 instructions.
2853 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2854 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2857 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
2859 Pop the last pushed segment from the stack, and set it.
2861 This command will switch back to the segment that was last pushed onto the
2862 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2863 command, and remove this entry from the stack.
2865 The assembler will print an error message if the segment stack is empty
2866 when this command is issued.
2868 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2871 <sect1><tt>.PROC</tt><label id=".PROC"><p>
2873 Start a nested lexical level with the given name and adds a symbol with this
2874 name to the enclosing scope. All new symbols from now on are in the local
2875 lexical level and are accessible from outside only via <ref id="scopesyntax"
2876 name="explicit scope specification">. Symbols defined outside this local
2877 level may be accessed as long as their names are not used for new symbols
2878 inside the level. Symbols names in other lexical levels do not clash, so you
2879 may use the same names for identifiers. The lexical level ends when the
2880 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
2881 may be nested up to a depth of 16 (this is an artificial limit to protect
2882 against errors in the source).
2884 Note: Macro names are always in the global level and in a separate name
2885 space. There is no special reason for this, it's just that I've never
2886 had any need for local macro definitions.
2891 .proc Clear ; Define Clear subroutine, start new level
2893 L1: sta Mem,y ; L1 is local and does not cause a
2894 ; duplicate symbol error if used in other
2897 bne L1 ; Reference local symbol
2899 .endproc ; Leave lexical level
2902 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
2906 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
2908 Enable the 65SC02 instructions set. This instruction set includes all
2911 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
2912 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2915 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
2917 Push the currently active segment onto a stack. The entries on the stack
2918 include the name of the segment and the segment type. The stack has a size
2921 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2922 to switch to another segment and to restore the old segment later, without
2923 even knowing the name and type of the current segment.
2925 The assembler will print an error message if the segment stack is already
2926 full, when this command is issued.
2928 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2931 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
2933 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
2934 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
2935 a constant expression that tells how many times the commands in the body
2936 should get repeated. Optionally, a comma and an identifier may be specified.
2937 If this identifier is found in the body of the repeat statement, it is
2938 replaced by the current repeat count (starting with zero for the first time
2939 the body is repeated).
2941 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
2942 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
2943 level will be used, not the one from the outer level.
2947 The following macro will emit a string that is "encrypted" in that all
2948 characters of the string are XORed by the value $55.
2952 .repeat .strlen(Arg), I
2953 .byte .strat(Arg, I) ^ $55
2958 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
2961 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
2963 Switch back to relocatable mode. See the <tt><ref id=".ORG"
2964 name=".ORG"></tt> command.
2967 <sect1><tt>.RES</tt><label id=".RES"><p>
2969 Reserve storage. The command is followed by one or two constant
2970 expressions. The first one is mandatory and defines, how many bytes of
2971 storage should be defined. The second, optional expression must by a
2972 constant byte value that will be used as value of the data. If there
2973 is no fill value given, the linker will use the value defined in the
2974 linker configuration file (default: zero).
2979 ; Reserve 12 bytes of memory with value $AA
2984 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
2986 Switch to the RODATA segment. The name of the RODATA segment is always
2987 "RODATA", so this is a shortcut for
2993 The RODATA segment is a segment that is used by the compiler for
2994 readonly data like string constants.
2996 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2999 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3001 Start a nested lexical level with the given name. All new symbols from now
3002 on are in the local lexical level and are accessible from outside only via
3003 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3004 outside this local level may be accessed as long as their names are not used
3005 for new symbols inside the level. Symbols names in other lexical levels do
3006 not clash, so you may use the same names for identifiers. The lexical level
3007 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3008 read. Lexical levels may be nested up to a depth of 16 (this is an
3009 artificial limit to protect against errors in the source).
3011 Note: Macro names are always in the global level and in a separate name
3012 space. There is no special reason for this, it's just that I've never
3013 had any need for local macro definitions.
3018 .scope Error ; Start new scope named Error
3020 File = 1 ; File error
3021 Parse = 2 ; Parse error
3022 .endproc ; Close lexical level
3025 lda #Error::File ; Use symbol from scope Error
3028 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3032 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3034 Switch to another segment. Code and data is always emitted into a
3035 segment, that is, a named section of data. The default segment is
3036 "CODE". There may be up to 254 different segments per object file
3037 (and up to 65534 per executable). There are shortcut commands for
3038 the most common segments ("CODE", "DATA" and "BSS").
3040 The command is followed by a string containing the segment name (there are
3041 some constraints for the name - as a rule of thumb use only those segment
3042 names that would also be valid identifiers). There may also be an optional
3043 address size separated by a colon. See the section covering <tt/<ref
3044 id="address-sizes" name="address sizes">/ for more information.
3046 The default address size for a segment depends on the memory model specified
3047 on the command line. The default is "absolute", which means that you don't
3048 have to use an address size modifier in most cases.
3050 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3051 That is, the segment will reside somewhere in core memory outside the zero
3052 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3053 page and direct (short) addressing is possible for data in this segment.
3055 Beware: Only labels in a segment with the zeropage attribute are marked
3056 as reachable by short addressing. The `*' (PC counter) operator will
3057 work as in other segments and will create absolute variable values.
3059 Please note that a segment cannot have two different address sizes. A
3060 segment specified as zeropage cannot be declared as being absolute later.
3065 .segment "ROM2" ; Switch to ROM2 segment
3066 .segment "ZP2": zeropage ; New direct segment
3067 .segment "ZP2" ; Ok, will use last attribute
3068 .segment "ZP2": absolute ; Error, redecl mismatch
3071 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3072 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3073 id=".RODATA" name=".RODATA"></tt>
3076 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3078 Switch the CPU instruction set. The command is followed by a string that
3079 specifies the CPU. Possible values are those that can also be supplied to
3080 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3081 namely: 6502, 6502X, 65SC02, 65C02, 65816 and sunplus. Please note that
3082 support for the sunplus CPU is not available in the freeware version,
3083 because the instruction set of the sunplus CPU is "proprietary and
3086 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3087 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3088 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3089 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3090 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3091 <tt><ref id=".P02" name=".P02"></tt>,
3092 <tt><ref id=".P816" name=".P816"></tt>,
3093 <tt><ref id=".PC02" name=".PC02"></tt>,
3094 <tt><ref id=".PSC02" name=".PSC02"></tt>
3097 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3099 Switch on or off smart mode. The command must be followed by a '+' or '-'
3100 character to switch the option on or off respectively. The default is off
3101 (that is, the assembler doesn't try to be smart), but this default may be
3102 changed by the -s switch on the command line.
3104 In smart mode the assembler will do the following:
3107 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3108 and update the operand sizes accordingly. If the operand of such an
3109 instruction cannot be evaluated by the assembler (for example, because
3110 the operand is an imported symbol), a warning is issued. Beware: Since
3111 the assembler cannot trace the execution flow this may lead to false
3112 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3113 instructions to tell the assembler about the current settings.
3114 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3115 used within a procedure declared as <tt/far/, or if the procedure has
3116 no explicit address specification, but it is <tt/far/ because of the
3124 .smart - ; Stop being smart
3127 See: <tt><ref id=".A16" name=".A16"></tt>,
3128 <tt><ref id=".A8" name=".A8"></tt>,
3129 <tt><ref id=".I16" name=".I16"></tt>,
3130 <tt><ref id=".I8" name=".I8"></tt>
3133 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3135 Starts a struct definition. Structs are covered in a separate section named
3136 <ref id="structs" name=""Structs and unions"">.
3138 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3141 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3143 Enable the SunPlus instructions set. This command will not work in the
3144 freeware version of the assembler, because the instruction set is
3145 "proprietary and confidential".
3147 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3148 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3149 <tt><ref id=".P816" name=".P816"></tt>
3152 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3154 Allocate space for a struct or union.
3165 .tag Point ; Allocate 4 bytes
3169 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3171 Force an assembly warning. The assembler will output a warning message
3172 preceded by "User warning". This warning will always be output, even if
3173 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3174 command line option.
3176 This command may be used to output possible problems when assembling
3185 .warning "Forward jump in jne, cannot optimize!"
3195 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
3196 name=".OUT"></tt> directives.
3199 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3201 Define word sized data. Must be followed by a sequence of (word ranged,
3202 but not necessarily constant) expressions.
3207 .word $0D00, $AF13, _Clear
3211 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3213 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3214 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3218 .segment "ZEROPAGE", zeropage
3221 Because of the "zeropage" attribute, labels declared in this segment are
3222 addressed using direct addressing mode if possible. You <em/must/ instruct
3223 the linker to place this segment somewhere in the address range 0..$FF
3224 otherwise you will get errors.
3226 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3230 <sect>Macros<label id="macros"><p>
3233 <sect1>Introduction<p>
3235 Macros may be thought of as "parametrized super instructions". Macros are
3236 sequences of tokens that have a name. If that name is used in the source
3237 file, the macro is "expanded", that is, it is replaced by the tokens that
3238 were specified when the macro was defined.
3241 <sect1>Macros without parameters<p>
3243 In it's simplest form, a macro does not have parameters. Here's an
3247 .macro asr ; Arithmetic shift right
3248 cmp #$80 ; Put bit 7 into carry
3249 ror ; Rotate right with carry
3253 The macro above consists of two real instructions, that are inserted into
3254 the code, whenever the macro is expanded. Macro expansion is simply done
3255 by using the name, like this:
3264 <sect1>Parametrized macros<p>
3266 When using macro parameters, macros can be even more useful:
3280 When calling the macro, you may give a parameter, and each occurrence of
3281 the name "addr" in the macro definition will be replaced by the given
3300 A macro may have more than one parameter, in this case, the parameters
3301 are separated by commas. You are free to give less parameters than the
3302 macro actually takes in the definition. You may also leave intermediate
3303 parameters empty. Empty parameters are replaced by empty space (that is,
3304 they are removed when the macro is expanded). If you have a look at our
3305 macro definition above, you will see, that replacing the "addr" parameter
3306 by nothing will lead to wrong code in most lines. To help you, writing
3307 macros with a variable parameter list, there are some control commands:
3309 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3310 returns true, if there are any tokens on the remainder of the line. Since
3311 empty parameters are replaced by nothing, this may be used to test if a given
3312 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3315 Look at this example:
3318 .macro ldaxy a, x, y
3331 This macro may be called as follows:
3334 ldaxy 1, 2, 3 ; Load all three registers
3336 ldaxy 1, , 3 ; Load only a and y
3338 ldaxy , , 3 ; Load y only
3341 There's another helper command for determining, which macro parameters are
3342 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3343 replaced by the parameter count given, <em/including/ intermediate empty macro
3347 ldaxy 1 ; .PARAMCOUNT = 1
3348 ldaxy 1,,3 ; .PARAMCOUNT = 3
3349 ldaxy 1,2 ; .PARAMCOUNT = 2
3350 ldaxy 1, ; .PARAMCOUNT = 2
3351 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3354 Macro parameters may optionally be enclosed into curly braces. This allows the
3355 inclusion of tokens that would otherwise terminate the parameter (the comma in
3356 case of a macro parameter).
3359 .macro foo arg1, arg2
3363 foo ($00,x) ; Two parameters passed
3364 foo {($00,x)} ; One parameter passed
3367 In the first case, the macro is called with two parameters: '<tt/($00/'
3368 and 'x)'. The comma is not passed to the macro, since it is part of the
3369 calling sequence, not the parameters.
3371 In the second case, '($00,x)' is passed to the macro, this time
3372 including the comma.
3375 <sect1>Detecting parameter types<p>
3377 Sometimes it is nice to write a macro that acts differently depending on the
3378 type of the argument supplied. An example would be a macro that loads a 16 bit
3379 value from either an immediate operand, or from memory. The <tt/<ref
3380 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3381 functions will allow you to do exactly this:
3385 .if (.match (.left (1, {arg}), #))
3387 lda #<(.right (.tcount ({arg})-1, {arg}))
3388 ldx #>(.right (.tcount ({arg})-1, {arg}))
3390 ; assume absolute or zero page
3397 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3398 check if its argument begins with a hash mark. If so, two immediate loads are
3399 emitted, Otherwise a load from an absolute zero page memory location is
3400 assumed. Please note how the curly braces are used to enclose parameters to
3401 pseudo functions handling token lists. This is necessary, because the token
3402 lists may include commas or parens, which would be treated by the assembler
3405 The macro can be used as
3410 ldax #$1234 ; X=$12, A=$34
3412 ldax foo ; X=$56, A=$78
3416 <sect1>Recursive macros<p>
3418 Macros may be used recursively:
3421 .macro push r1, r2, r3
3430 There's also a special macro to help writing recursive macros: <tt><ref
3431 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3435 .macro push r1, r2, r3, r4, r5, r6, r7
3437 ; First parameter is empty
3443 push r2, r3, r4, r5, r6, r7
3447 When expanding this macro, the expansion will push all given parameters
3448 until an empty one is encountered. The macro may be called like this:
3451 push $20, $21, $32 ; Push 3 ZP locations
3452 push $21 ; Push one ZP location
3456 <sect1>Local symbols inside macros<p>
3458 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3459 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3460 Have a look at the inc16 macro above. Here is it again:
3474 If you have a closer look at the code, you will notice, that it could be
3475 written more efficiently, like this:
3486 But imagine what happens, if you use this macro twice? Since the label
3487 "Skip" has the same name both times, you get a "duplicate symbol" error.
3488 Without a way to circumvent this problem, macros are not as useful, as
3489 they could be. One solution is, to start a new lexical block inside the
3503 Now the label is local to the block and not visible outside. However,
3504 sometimes you want a label inside the macro to be visible outside. To make
3505 that possible, there's a new command that's only usable inside a macro
3506 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3507 or more symbols as local to the macro expansion. The names of local variables
3508 are replaced by a unique name in each separate macro expansion. So we could
3509 also solve the problem above by using <tt/.LOCAL/:
3513 .local Skip ; Make Skip a local symbol
3520 Skip: ; Not visible outside
3525 <sect1>C style macros<p>
3527 Starting with version 2.5 of the assembler, there is a second macro type
3528 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3529 similar to the classic macro type described above, but behaviour is sometimes
3534 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3535 span more than a line. You may use line continuation (see <tt><ref
3536 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3537 more than one line for increased readability, but the macro itself
3538 may not contain an end-of-line token.
3540 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3541 the name space with classic macros, but they are detected and replaced
3542 at the scanner level. While classic macros may be used in every place,
3543 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3544 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3545 they are more versatile in some situations.
3547 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3548 parameters. While classic macros may have empty parameters, this is
3549 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3550 For this macro type, the number of actual parameters must match
3551 exactly the number of formal parameters.
3553 To make this possible, formal parameters are enclosed in braces when
3554 defining the macro. If there are no parameters, the empty braces may
3557 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3558 contain end-of-line tokens, there are things that cannot be done. They
3559 may not contain several processor instructions for example. So, while
3560 some things may be done with both macro types, each type has special
3561 usages. The types complement each other.
3565 Let's look at a few examples to make the advantages and disadvantages
3568 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3569 following <tt/.DEFINE/:
3574 foo EQU $1234 ; This is accepted now
3577 You may use the directive to define string constants used elsewhere:
3580 ; Define the version number
3581 .define VERSION "12.3a"
3587 Macros with parameters may also be useful:
3590 .define DEBUG(message) .out message
3592 DEBUG "Assembling include file #3"
3595 Note that, while formal parameters have to be placed in braces, this is
3596 not true for the actual parameters. Beware: Since the assembler cannot
3597 detect the end of one parameter, only the first token is used. If you
3598 don't like that, use classic macros instead:
3606 (This is an example where a problem can be solved with both macro types).
3609 <sect1>Characters in macros<p>
3611 When using the <ref id="option-t" name="-t"> option, characters are translated
3612 into the target character set of the specific machine. However, this happens
3613 as late as possible. This means that strings are translated if they are part
3614 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3615 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3616 used as part of an expression.
3618 This behaviour is very intuitive outside of macros but may be confusing when
3619 doing more complex macros. If you compare characters against numeric values,
3620 be sure to take the translation into account.
3625 <sect>Macro packages<label id="macropackages"><p>
3627 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3628 macro packages may be included with just one command. Available macro packages
3632 <sect1><tt>.MACPACK generic</tt><p>
3634 This macro package defines macros that are useful in almost any program.
3635 Currently, two macros are defined:
3650 <sect1><tt>.MACPACK longbranch</tt><p>
3652 This macro package defines long conditional jumps. They are named like the
3653 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3654 definition for the "<tt/jeq/" macro, the other macros are built using the same
3659 .if .def(Target) .and ((*+2)-(Target) <= 127)
3668 All macros expand to a short branch, if the label is already defined (back
3669 jump) and is reachable with a short jump. Otherwise the macro expands to a
3670 conditional branch with the branch condition inverted, followed by an absolute
3671 jump to the actual branch target.
3673 The package defines the following macros:
3676 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3681 <sect1><tt>.MACPACK cbm</tt><p>
3683 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3684 string as argument and places this string into memory translated into screen
3688 <sect1><tt>.MACPACK cpu</tt><p>
3690 This macro package does not define any macros but constants used to examine
3691 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3692 each supported CPU a constant similar to
3703 is defined. These constants may be used to determine the exact type of the
3704 currently enabled CPU. In addition to that, for each CPU instruction set,
3705 another constant is defined:
3716 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3717 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3718 currently enabled CPU supports a specific instruction set. For example the
3719 65C02 supports all instructions of the 65SC02 CPU, so it has the
3720 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3724 .if (.cpu .bitand CPU_ISET_65SC02)
3732 it is possible to determine if the
3738 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3739 CPUs (the latter two are upwards compatible to the 65SC02).
3743 <sect>Predefined constants<label id="predefined-constants"><p>
3745 For better orthogonality, the assembler defines similar symbols as the
3746 compiler, depending on the target system selected:
3749 <item><tt/__ACE__/ - Target system is <tt/ace/
3750 <item><tt/__APPLE2__",/ - Target system is <tt/apple2/
3751 <item><tt/__APPLE2ENH__",/ - Target system is <tt/apple2enh/
3752 <item><tt/__ATARI__/ - Target system is <tt/atari/
3753 <item><tt/__ATMOS__",/ - Target system is <tt/atmos/
3754 <item><tt/__BBC__",/ - Target system is <tt/bbc/
3755 <item><tt/__C128__/ - Target system is <tt/c128/
3756 <item><tt/__C16__/ - Target system is <tt/c16/
3757 <item><tt/__C64__/ - Target system is <tt/c64/
3758 <item><tt/__CBM__/ - Target is a Commodore system
3759 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
3760 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
3761 <item><tt/__GEOS__",/ - Target system is <tt/geos/
3762 <item><tt/__LUNIX__",/ - Target system is <tt/lunix/
3763 <item><tt/__NES__",/ - Target system is <tt/nes/
3764 <item><tt/__PET__/ - Target system is <tt/pet/
3765 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
3766 <item><tt/__SUPERVISION__",/ - Target system is <tt/supervision/
3767 <item><tt/__VIC20__/ - Target system is <tt/vic20/
3771 <sect>Structs and unions<label id="structs"><p>
3775 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3776 are to some degree comparable to their C counterparts. Both have a list of
3777 members. Each member allocates storage and may optionally have a name, which,
3778 in case of a struct, is the offset from the beginning and, in case of a union,
3782 <sect1>Declaration<p>
3784 Here is an example for a very simple struct with two members and a total size
3794 A union shares the total space between all its members, its size is the same
3795 as that of the largest member.
3797 A struct or union must not necessarily have a name. If it is anonymous, no
3798 local scope is opened, the identifiers used to name the members are placed
3799 into the current scope instead.
3801 A struct may contain unnamed members and definitions of local structs. The
3802 storage allocators may contain a multiplier, as in the example below:
3807 .word 2 ; Allocate two words
3814 <sect1>The <tt/.TAG/ keyword<p>
3816 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
3817 for an already defined struct or unions within another struct:
3831 Space for a struct or union may be allocated using the <ref id=".TAG"
3832 name=".TAG"> directive.
3838 Currently, members are just offsets from the start of the struct or union. To
3839 access a field of a struct, the member offset has to be added to the address
3840 of the struct itself:
3843 lda C+Circle::Radius ; Load circle radius into A
3846 This may change in a future version of the assembler.
3849 <sect1>Limitations<p>
3851 Structs and unions are currently implemented as nested symbol tables (in fact,
3852 they were a by-product of the improved scoping rules). Currently, the
3853 assembler has no idea of types. This means that the <ref id=".TAG"
3854 name=".TAG"> keyword will only allocate space. You won't be able to initialize
3855 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
3856 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
3857 this structure accessible by using the '::' operator.
3861 <sect>Module constructors/destructors<label id="condes"><p>
3863 <em>Note:</em> This section applies mostly to C programs, so the explanation
3864 below uses examples from the C libraries. However, the feature may also be
3865 useful for assembler programs.
3870 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
3871 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
3872 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
3873 special way. The linker is able to generate tables with all functions of a
3874 specific type. Such a table will <em>only</em> include symbols from object
3875 files that are linked into a specific executable. This may be used to add
3876 initialization and cleanup code for library modules, or a table of interrupt
3879 The C heap functions are an example where module initialization code is used.
3880 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
3881 variables that contain the start and the end of the heap, pointers to the free
3882 list and so on. Since the end of the heap depends on the size and start of the
3883 stack, it must be initialized at runtime. However, initializing these
3884 variables for programs that do not use the heap are a waste of time and
3887 So the central module defines a function that contains initialization code and
3888 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
3889 this module is added to an executable by the linker, the initialization
3890 function will be placed into the table of constructors by the linker. The C
3891 startup code will call all constructors before <tt/main/ and all destructors
3892 after <tt/main/, so without any further work, the heap initialization code is
3893 called once the module is linked in.
3895 While it would be possible to add explicit calls to initialization functions
3896 in the startup code, the new approach has several advantages:
3900 If a module is not included, the initialization code is not linked in and not
3901 called. So you don't pay for things you don't need.
3904 Adding another library that needs initialization does not mean that the
3905 startup code has to be changed. Before we had module constructors and
3906 destructors, the startup code for all systems had to be adjusted to call the
3907 new initialization code.
3910 The feature saves memory: Each additional initialization function needs just
3911 two bytes in the table (a pointer to the function).
3916 <sect1>Calling order<p>
3918 The symbols are sorted in increasing priority order by the linker when using
3919 one of the builtin linker configurations, so the functions with lower
3920 priorities come first and are followed by those with higher priorities. The C
3921 library runtime subroutine that walks over the function tables calls the
3922 functions starting from the top of the table - which means that functions with
3923 a high priority are called first.
3925 So when using the C runtime, functions are called with high priority functions
3926 first, followed by low priority functions.
3931 When using these special symbols, please take care of the following:
3936 The linker will only generate function tables, it will not generate code to
3937 call these functions. If you're using the feature in some other than the
3938 existing C environments, you have to write code to call all functions in a
3939 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
3940 in the C runtime for an example on how to do this.
3943 The linker will only add addresses of functions that are in modules linked to
3944 the executable. This means that you have to be careful where to place the
3945 condes functions. If initialization or an irq handler is needed for a group of
3946 functions, be sure to place the function into a module that is linked in
3947 regardless of which function is called by the user.
3950 The linker will generate the tables only when requested to do so by the
3951 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
3952 be requested separately.
3955 Constructors and destructors may have priorities. These priorities determine
3956 the order of the functions in the table. If your initialization or cleanup code
3957 does depend on other initialization or cleanup code, you have to choose the
3958 priority for the functions accordingly.
3961 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
3962 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
3963 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
3964 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
3965 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
3966 (interruptor). The linker generates a separate table for each type on request.
3971 <sect>Porting sources from other assemblers<p>
3973 Sometimes it is necessary to port code written for older assemblers to ca65.
3974 In some cases, this can be done without any changes to the source code by
3975 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
3976 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
3979 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
3980 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
3981 done by the linker. Most other assemblers generate absolute code, placement is
3982 done within the assembler and there is no external linker.
3984 In general it is not a good idea to write new code using the emulation
3985 features of the assembler, but there may be situations where even this rule is
3990 You need to use some of the ca65 emulation features to simulate the behaviour
3991 of such simple assemblers.
3994 <item>Prepare your sourcecode like this:
3997 ; if you want TASS style labels without colons
3998 .feature labels_without_colons
4000 ; if you want TASS style character constants
4001 ; ("a" instead of the default 'a')
4002 .feature loose_char_term
4004 .word *+2 ; the cbm load address
4009 notice that the two emulation features are mostly useful for porting
4010 sources originally written in/for TASS, they are not needed for the
4011 actual "simple assembler operation" and are not recommended if you are
4012 writing new code from scratch.
4014 <item>Replace all program counter assignments (which are not possible in ca65
4015 by default, and the respective emulation feature works different from what
4016 you'd expect) by another way to skip to another memory location, for example
4017 the <tt><ref id=".RES" name=".RES"></tt>directive.
4021 .res $2000-* ; reserve memory up to $2000
4024 notice that other than the original TASS, ca65 can never move the
4025 programmcounter backwards - think of it as if you are assembling to disc with
4028 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4029 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4030 of <tt/.goto/, everything involving loops must be replaced by
4031 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4033 <item>To assemble code to a different address than it is executed at, use the
4034 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4035 <tt/.offs/-constructs.
4042 .reloc ; back to normal
4045 <item>Then assemble like this:
4048 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4051 notice that you need to use the actual start address minus two, since two
4052 bytes are used for the cbm load address.
4057 <sect>Bugs/Feedback<p>
4059 If you have problems using the assembler, if you find any bugs, or if
4060 you're doing something interesting with the assembler, I would be glad to
4061 hear from you. Feel free to contact me by email
4062 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4068 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4069 Bassewitz. For usage of the binaries and/or sources the following
4070 conditions do apply:
4072 This software is provided 'as-is', without any expressed or implied
4073 warranty. In no event will the authors be held liable for any damages
4074 arising from the use of this software.
4076 Permission is granted to anyone to use this software for any purpose,
4077 including commercial applications, and to alter it and redistribute it
4078 freely, subject to the following restrictions:
4081 <item> The origin of this software must not be misrepresented; you must not
4082 claim that you wrote the original software. If you use this software
4083 in a product, an acknowledgment in the product documentation would be
4084 appreciated but is not required.
4085 <item> Altered source versions must be plainly marked as such, and must not
4086 be misrepresented as being the original software.
4087 <item> This notice may not be removed or altered from any source