1 <!doctype linuxdoc system>
4 <title>ca65 Users Guide
5 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
6 <date>2000-07-19, 2000-11-29, 2001-10-02, 2005-09-08
9 ca65 is a powerful macro assembler for the 6502, 65C02 and 65816 CPUs. It is
10 used as a companion assembler for the cc65 crosscompiler, but it may also be
11 used as a standalone product.
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
22 compiler, originally developed by John R. Dunning. I had some problems with
23 ra65 and the copyright does not permit some things which I wanted to be
24 possible, so I decided to write a completely new assembler/linker/archiver
25 suite for the cc65 compiler. ca65 is part of this suite.
27 Some parts of the assembler (code generation and some routines for symbol
28 table handling) are taken from an older crossassembler named a816 written
29 by me a long time ago.
32 <sect1>Design criteria<p>
34 Here's a list of the design criteria, that I considered important for the
39 <item> The assembler must support macros. Macros are not essential, but they
40 make some things easier, especially when you use the assembler in the
41 backend of a compiler.
42 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
43 thinking about a 65816 backend for the C compiler, and even my old
44 a816 assembler had support for these CPUs, so this wasn't really a
46 <item> The assembler must produce relocatable code. This is necessary for the
47 compiler support, and it is more convenient.
48 <item> Conditional assembly must be supported. This is a must for bigger
49 projects written in assembler (like Elite128).
50 <item> The assembler must support segments, and it must support more than
51 three segments (this is the count, most other assemblers support).
52 Having more than one code segments helps developing code for systems
53 with a divided ROM area (like the C64).
54 <item> The linker must be able to resolve arbitrary expressions. It should
55 be able to get things like
62 <item> True lexical nesting for symbols. This is very convenient for larger
64 <item> "Cheap" local symbols without lexical nesting for those quick, late
66 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
67 introduced the concept into the object file format use by the new cc65
69 <item> The assembler will be a one pass assembler. There was no real need for
70 this decision, but I've written several multipass assemblers, and it
71 started to get boring. A one pass assembler needs much more elaborated
72 data structures, and because of that it's much more fun:-)
73 <item> Non-GPLed code that may be used in any project without restrictions or
74 fear of "GPL infecting" other code.
82 <sect1>Command line option overview<p>
84 The assembler accepts the following options:
87 ---------------------------------------------------------------------------
88 Usage: ca65 [options] file
90 -D name[=value] Define a symbol
91 -I dir Set an include directory search path
92 -U Mark unresolved symbols as import
93 -V Print the assembler version
94 -W n Set warning level n
95 -g Add debug info to object file
97 -i Ignore case of symbols
98 -l Create a listing if assembly was ok
99 -mm model Set the memory model
100 -o name Name the output file
102 -t sys Set the target system
103 -v Increase verbosity
106 --auto-import Mark unresolved symbols as import
107 --cpu type Set cpu type
108 --debug-info Add debug info to object file
109 --feature name Set an emulation feature
110 --forget-inc-paths Forget include search paths
111 --help Help (this text)
112 --ignore-case Ignore case of symbols
113 --include-dir dir Set an include directory search path
114 --listing Create a listing if assembly was ok
115 --list-bytes n Maximum number of bytes per listing line
116 --macpack-dir dir Set a macro package directory
117 --memory-model model Set the memory model
118 --pagelength n Set the page length for the listing
119 --smart Enable smart mode
120 --target sys Set the target system
121 --verbose Increase verbosity
122 --version Print the assembler version
123 ---------------------------------------------------------------------------
127 <sect1>Command line options in detail<p>
129 Here is a description of all the command line options:
133 <label id="option--cpu">
134 <tag><tt>--cpu type</tt></tag>
136 Set the default for the CPU type. The option takes a parameter, which
139 6502, 65SC02, 65C02, 65816, sunplus, sweet16, HuC6280
141 The sunplus cpu is not available in the freeware version, because the
142 instruction set is "proprietary and confidential".
145 <label id="option--feature">
146 <tag><tt>--feature name</tt></tag>
148 Enable an emulation feature. This is identical as using <tt/.FEATURE/
149 in the source with two exceptions: Feature names must be lower case, and
150 each feature must be specified by using an extra <tt/--feature/ option,
151 comma separated lists are not allowed.
153 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
154 command for a list of emulation features.
157 <tag><tt>--forget-inc-paths</tt></tag>
159 Forget the builtin include paths. This is most useful when building
160 customized assembler modules, in which case the standard header files should
164 <label id="option-g">
165 <tag><tt>-g, --debug-info</tt></tag>
167 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
168 used, the assembler will add a section to the object file that contains
169 all symbols (including local ones) together with the symbol values and
170 source file positions. The linker will put these additional symbols into
171 the VICE label file, so even local symbols can be seen in the VICE
175 <tag><tt>-h, --help</tt></tag>
177 Print the short option summary shown above.
180 <tag><tt>-i, --ignore-case</tt></tag>
182 This option makes the assembler case insensitive on identifiers and labels.
183 This option will override the default, but may itself be overridden by the
184 <tt><ref id=".CASE" name=".CASE"></tt> control command.
187 <tag><tt>-l, --listing</tt></tag>
189 Generate an assembler listing. The listing file will always have the
190 name of the main input file with the extension replaced by ".lst". This
191 may change in future versions.
194 <tag><tt>--list-bytes n</tt></tag>
196 Set the maximum number of bytes printed in the listing for one line of
197 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
198 for more information. The value zero can be used to encode an unlimited
199 number of printed bytes.
202 <tag><tt>--macpack-dir dir</tt></tag>
204 This options allows to specify a directory containing macro files that are
205 used instead of the builtin images when a <tt><ref id=".MACPACK"
206 name=".MACPACK"></tt> directive is encountered. If <tt>--macpack-dir</tt>
207 was specified, a <tt>.mac</tt> extension is added to the package name and
208 the resulting file is loaded from the given directory. This is most useful
209 when debugging the builtin macro packages.
212 <tag><tt>-mm model, --memory-model model</tt></tag>
214 Define the default memory model. Possible model specifiers are near, far and
218 <tag><tt>-o name</tt></tag>
220 The default output name is the name of the input file with the extension
221 replaced by ".o". If you don't like that, you may give another name with
222 the -o option. The output file will be placed in the same directory as
223 the source file, or, if -o is given, the full path in this name is used.
226 <tag><tt>--pagelength n</tt></tag>
228 sets the length of a listing page in lines. See the <tt><ref
229 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
232 <tag><tt>-s, --smart-mode</tt></tag>
234 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
235 pseudo instruction) the assembler will track usage of the <tt/REP/ and
236 <tt/SEP/ instructions in 65816 mode and update the operand sizes
237 accordingly. If the operand of such an instruction cannot be evaluated by
238 the assembler (for example, because the operand is an imported symbol), a
241 Beware: Since the assembler cannot trace the execution flow this may
242 lead to false results in some cases. If in doubt, use the .ixx and .axx
243 instructions to tell the assembler about the current settings. Smart
244 mode is off by default.
247 <label id="option-t">
248 <tag><tt>-t sys, --target sys</tt></tag>
250 Set the target system. This will enable translation of character strings
251 and character constants into the character set of the target platform.
252 The default for the target system is "none", which means that no translation
253 will take place. The assembler supports the same target systems as the
254 compiler, see there for a list.
257 <tag><tt>-v, --verbose</tt></tag>
259 Increase the assembler verbosity. Usually only needed for debugging
260 purposes. You may use this option more than one time for even more
264 <tag><tt>-D</tt></tag>
266 This option allows you to define symbols on the command line. Without a
267 value, the symbol is defined with the value zero. When giving a value,
268 you may use the '$' prefix for hexadecimal symbols. Please note
269 that for some operating systems, '$' has a special meaning, so
270 you may have to quote the expression.
273 <tag><tt>-I dir, --include-dir dir</tt></tag>
275 Name a directory which is searched for include files. The option may be
276 used more than once to specify more than one directory to search. The
277 current directory is always searched first before considering any
278 additional directories. See also the section about <ref id="search-paths"
279 name="search paths">.
282 <tag><tt>-U, --auto-import</tt></tag>
284 Mark symbols that are not defined in the sources as imported symbols. This
285 should be used with care since it delays error messages about typos and such
286 until the linker is run. The compiler uses the equivalent of this switch
287 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
288 symbols for the runtime library. However, the compiler is supposed to
289 generate code that runs through the assembler without problems, something
290 which is not always true for assembler programmers.
293 <tag><tt>-V, --version</tt></tag>
295 Print the version number of the assembler. If you send any suggestions
296 or bugfixes, please include the version number.
299 <label id="option-W">
300 <tag><tt>-Wn</tt></tag>
302 Set the warning level for the assembler. Using -W2 the assembler will
303 even warn about such things like unused imported symbols. The default
304 warning level is 1, and it would probably be silly to set it to
312 <sect>Search paths<label id="search-paths"><p>
314 Include files are searched in the following places:
317 <item>The current directory.
318 <item>A compiled-in directory, which is often <tt>/usr/lib/cc65/asminc</tt>
320 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
321 <item>A subdirectory named <tt/asminc/ of the directory defined in the
322 environment variable <tt/CC65_HOME/, if it is defined.
323 <item>Any directory added with the <tt/-I/ option on the command line.
328 <sect>Input format<p>
330 <sect1>Assembler syntax<p>
332 The assembler accepts the standard 6502/65816 assembler syntax. One line may
333 contain a label (which is identified by a colon), and, in addition to the
334 label, an assembler mnemonic, a macro, or a control command (see section <ref
335 id="control-commands" name="Control Commands"> for supported control
336 commands). Alternatively, the line may contain a symbol definition using
337 the '=' token. Everything after a semicolon is handled as a comment (that is,
340 Here are some examples for valid input lines:
343 Label: ; A label and a comment
344 lda #$20 ; A 6502 instruction plus comment
345 L1: ldx #$20 ; Same with label
346 L2: .byte "Hello world" ; Label plus control command
347 mymac $20 ; Macro expansion
348 MySym = 3*L1 ; Symbol definition
349 MaSym = Label ; Another symbol
352 The assembler accepts
355 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
356 <tt><ref id=".P02" name=".P02"></tt> command was given).
357 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
358 <ref id="6502X-mode" name="6502X mode">.
359 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
360 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
361 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
362 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
363 <item>all valid 65618 mnemonics when in 65816 mode (after the
364 <tt><ref id=".P816" name=".P816"></tt> command was given).
365 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
366 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
372 In 65816 mode several aliases are accepted in addition to the official
376 BGE is an alias for BCS
377 BLT is an alias for BCC
378 CPA is an alias for CMP
379 DEA is an alias for DEC A
380 INA is an alias for INC A
381 SWA is an alias for XBA
382 TAD is an alias for TCD
383 TAS is an alias for TCS
384 TDA is an alias for TDC
385 TSA is an alias for TSC
390 <sect1>6502X mode<label id="6502X-mode"><p>
392 6502X mode is an extension to the normal 6502 mode. In this mode, several
393 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
394 these instructions are illegal, there are no official mnemonics for them. The
395 unofficial ones are taken from <htmlurl
396 url="http://oxyron.net/graham/opcodes02.html"
397 name="http://oxyron.net/graham/opcodes02.html">. Please note that only the
398 ones marked as "stable" are supported. The following table uses information
399 from the mentioned web page, for more information, see there.
402 <item><tt>ALR: A:=(A and #{imm})*2;</tt>
403 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
404 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
405 <item><tt>AXS: X:=A and X-#{imm};</tt>
406 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
407 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
408 <item><tt>LAS: A,X,S:={adr} and S;</tt>
409 <item><tt>LAX: A,X:={adr};</tt>
410 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
411 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
412 <item><tt>SAX: {adr}:=A and X;</tt>
413 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
414 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
419 <sect1>sweet16 mode<label id="sweet16-mode"><p>
421 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
422 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
423 generate code for this pseudo CPU when switched into sweet16 mode. The
424 following is special in sweet16 mode:
428 <item>The '@' character denotes indirect addressing and is no longer available
429 for cheap local labels. If you need cheap local labels, you will have to
430 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
431 name=".LOCALCHAR">/ command.
433 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
434 these identifiers are reserved words.
438 Please note that the assembler does neither supply the interpreter needed for
439 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
440 nor does it call the interpreter. All this must be done by your program. Apple
441 ][ programmers do probably know how to use sweet16 mode.
443 For more information about SWEET 16, see
444 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
445 name="http://www.6502.org/source/interpreters/sweet16.htm">.
448 <sect1>Number format<p>
450 For literal values, the assembler accepts the widely used number formats: A
451 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
452 denotes a binary value, and a bare number is interpreted as a decimal. There
453 are currently no octal values and no floats.
456 <sect1>Conditional assembly<p>
458 Please note that when using the conditional directives (<tt/.IF/ and friends),
459 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
460 that are not assembled. The reason for this behaviour is that the assembler
461 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
462 conversion of the input stream into tokens still takes place. As a consequence
463 conditional assembly directives may <bf/not/ be used to prevent normal text
464 (used as a comment or similar) from being assembled. <p>
470 <sect1>Expression evaluation<p>
472 All expressions are evaluated with (at least) 32 bit precision. An
473 expression may contain constant values and any combination of internal and
474 external symbols. Expressions that cannot be evaluated at assembly time
475 are stored inside the object file for evaluation by the linker.
476 Expressions referencing imported symbols must always be evaluated by the
480 <sect1>Size of an expression result<p>
482 Sometimes, the assembler must know about the size of the value that is the
483 result of an expression. This is usually the case, if a decision has to be
484 made, to generate a zero page or an absolute memory references. In this
485 case, the assembler has to make some assumptions about the result of an
489 <item> If the result of an expression is constant, the actual value is
490 checked to see if it's a byte sized expression or not.
491 <item> If the expression is explicitly casted to a byte sized expression by
492 one of the '>', '<' or '^' operators, it is a byte expression.
493 <item> If this is not the case, and the expression contains a symbol,
494 explicitly declared as zero page symbol (by one of the .importzp or
495 .exportzp instructions), then the whole expression is assumed to be
497 <item> If the expression contains symbols that are not defined, and these
498 symbols are local symbols, the enclosing scopes are searched for a
499 symbol with the same name. If one exists and this symbol is defined,
500 it's attributes are used to determine the result size.
501 <item> In all other cases the expression is assumed to be word sized.
504 Note: If the assembler is not able to evaluate the expression at assembly
505 time, the linker will evaluate it and check for range errors as soon as
509 <sect1>Boolean expressions<p>
511 In the context of a boolean expression, any non zero value is evaluated as
512 true, any other value to false. The result of a boolean expression is 1 if
513 it's true, and zero if it's false. There are boolean operators with extreme
514 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
515 operators are shortcut operators. That is, if the result of the expression is
516 already known, after evaluating the left hand side, the right hand side is
520 <sect1>Constant expressions<p>
522 Sometimes an expression must evaluate to a constant without looking at any
523 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
524 that decides if parts of the code are assembled or not. An expression used in
525 the <tt/.IF/ command cannot reference a symbol defined later, because the
526 decision about the <tt/.IF/ must be made at the point when it is read. If the
527 expression used in such a context contains only constant numerical values,
528 there is no problem. When unresolvable symbols are involved it may get harder
529 for the assembler to determine if the expression is actually constant, and it
530 is even possible to create expressions that aren't recognized as constant.
531 Simplifying the expressions will often help.
533 In cases where the result of the expression is not needed immediately, the
534 assembler will delay evaluation until all input is read, at which point all
535 symbols are known. So using arbitrary complex constant expressions is no
536 problem in most cases.
540 <sect1>Available operators<label id="operators"><p>
544 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
545 | Built-in string functions| 0@
547 | Built-in pseudo-variables| 1@
548 | Built-in pseudo-functions| 1@
549 +| Unary positive| 1@
550 -| Unary negative| 1@
552 .BITNOT| Unary bitwise not| 1@
554 .LOBYTE| Unary low-byte operator| 1@
556 .HIBYTE| Unary high-byte operator| 1@
558 .BANKBYTE| Unary bank-byte operator| 1@
560 *| Multiplication| 2@
562 .MOD| Modulo operator| 2@
564 .BITAND| Bitwise and| 2@
566 .BITXOR| Binary bitwise xor| 2@
568 .SHL| Shift-left operator| 2@
570 .SHR| Shift-right operator| 2@
572 +| Binary addition| 3@
573 -| Binary subtraction| 3@
575 .BITOR| Bitwise or| 3@
577 = | Compare operator (equal)| 4@
578 <>| Compare operator (not equal)| 4@
579 <| Compare operator (less)| 4@
580 >| Compare operator (greater)| 4@
581 <=| Compare operator (less or equal)| 4@
582 >=| Compare operator (greater or equal)| 4@
585 .AND| Boolean and| 5@
586 .XOR| Boolean xor| 5@
588 ||<newline>
592 .NOT| Boolean not| 7@<hline>
594 <caption>Available operators, sorted by precedence
597 To force a specific order of evaluation, parentheses may be used, as usual.
601 <sect>Symbols and labels<p>
603 A symbol or label is an identifier that starts with a letter and is followed
604 by letters and digits. Depending on some features enabled (see
605 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
606 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
607 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
608 other characters may be present. Use of identifiers consisting of a single
609 character will not work in all cases, because some of these identifiers are
610 reserved keywords (for example "A" is not a valid identifier for a label,
611 because it is the keyword for the accumulator).
613 The assembler allows you to use symbols instead of naked values to make
614 the source more readable. There are a lot of different ways to define and
615 use symbols and labels, giving a lot of flexibility.
617 <sect1>Numeric constants<p>
619 Numeric constants are defined using the equal sign or the label assignment
620 operator. After doing
626 may use the symbol "two" in every place where a number is expected, and it is
627 evaluated to the value 2 in this context. The label assignment operator causes
628 the same, but causes the symbol to be marked as a label, which may cause a
629 different handling in the debugger:
635 The right side can of course be an expression:
642 <sect1>Standard labels<p>
644 A label is defined by writing the name of the label at the start of the line
645 (before any instruction mnemonic, macro or pseudo directive), followed by a
646 colon. This will declare a symbol with the given name and the value of the
647 current program counter.
650 <sect1>Local labels and symbols<p>
652 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
653 create regions of code where the names of labels and symbols are local to this
654 region. They are not known outside of this region and cannot be accessed from
655 there. Such regions may be nested like PROCEDUREs in Pascal.
657 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
658 directive for more information.
661 <sect1>Cheap local labels<p>
663 Cheap local labels are defined like standard labels, but the name of the
664 label must begin with a special symbol (usually '@', but this can be
665 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
668 Cheap local labels are visible only between two non cheap labels. As soon as a
669 standard symbol is encountered (this may also be a local symbol if inside a
670 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
671 cheap local symbol goes out of scope.
673 You may use cheap local labels as an easy way to reuse common label
674 names like "Loop". Here is an example:
677 Clear: lda #$00 ; Global label
679 @Loop: sta Mem,y ; Local label
683 Sub: ... ; New global label
684 bne @Loop ; ERROR: Unknown identifier!
687 <sect1>Unnamed labels<p>
689 If you really want to write messy code, there are also unnamed labels. These
690 labels do not have a name (you guessed that already, didn't you?). A colon is
691 used to mark the absence of the name.
693 Unnamed labels may be accessed by using the colon plus several minus or plus
694 characters as a label designator. Using the '-' characters will create a back
695 reference (use the n'th label backwards), using '+' will create a forward
696 reference (use the n'th label in forward direction). An example will help to
719 As you can see from the example, unnamed labels will make even short
720 sections of code hard to understand, because you have to count labels
721 to find branch targets (this is the reason why I for my part do
722 prefer the "cheap" local labels). Nevertheless, unnamed labels are
723 convenient in some situations, so it's your decision.
726 <sect1>Using macros to define labels and constants<p>
728 While there are drawbacks with this approach, it may be handy in some
729 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
730 possible to define symbols or constants that may be used elsewhere. Since
731 the macro facility works on a very low level, there is no scoping. On the
732 other side, you may also define string constants this way (this is not
733 possible with the other symbol types).
739 .DEFINE version "SOS V2.3"
741 four = two * two ; Ok
744 .PROC ; Start local scope
745 two = 3 ; Will give "2 = 3" - invalid!
750 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
752 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
753 id="option-g" name="-g"> is given on the command line), global, local and
754 cheap local labels are written to the object file and will be available in the
755 symbol file via the linker. Unnamed labels are not written to the object file,
756 because they don't have a name which would allow to access them.
760 <sect>Scopes<label id="scopes"><p>
762 ca65 implements several sorts of scopes for symbols.
764 <sect1>Global scope<p>
766 All (non cheap local) symbols that are declared outside of any nested scopes
770 <sect1>Cheap locals<p>
772 A special scope is the scope for cheap local symbols. It lasts from one non
773 local symbol to the next one, without any provisions made by the programmer.
774 All other scopes differ in usage but use the same concept internally.
777 <sect1>Generic nested scopes<p>
779 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
780 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
781 The scope can have a name, in which case it is accessible from the outside by
782 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
783 have a name, all symbols created within the scope are local to the scope, and
784 aren't accessible from the outside.
786 A nested scope can access symbols from the local or from enclosing scopes by
787 name without using explicit scope names. In some cases there may be
788 ambiguities, for example if there is a reference to a local symbol that is not
789 yet defined, but a symbol with the same name exists in outer scopes:
801 In the example above, the <tt/lda/ instruction will load the value 3 into the
802 accumulator, because <tt/foo/ is redefined in the scope. However:
814 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
815 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
816 absolute mode is used instead. In fact, the assembler will not use absolute
817 mode by default, but it will search through the enclosing scopes for a symbol
818 with the given name. If one is found, the address size of this symbol is used.
819 This may lead to errors:
831 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
832 instruction, it will search for an already defined symbol <tt/foo/. It will
833 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
834 zeropage symbol. So the assembler will use zeropage addressing mode. If
835 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
836 the address in the <tt/lda/ instruction already translated, but since the new
837 value needs absolute addressing mode, this fails, and an error message "Range
840 Of course the most simple solution for the problem is to move the definition
841 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
842 rare cases when this cannot be done. In these cases, you can use one of the
843 address size override operators:
855 This will cause the <tt/lda/ instruction to be translated using absolute
856 addressing mode, which means changing the symbol reference later does not
860 <sect1>Nested procedures<p>
862 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
863 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
864 name, and a it will introduce a symbol with this name in the enclosing scope.
873 is actually the same as
882 This is the reason why a procedure must have a name. If you want a scope
883 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
885 <bf/Note:/ As you can see from the example above, scopes and symbols live in
886 different namespaces. There can be a symbol named <tt/foo/ and a scope named
887 <tt/foo/ without any conflicts (but see the section titled <ref
888 id="scopesearch" name=""Scope search order"">).
891 <sect1>Structs, unions and enums<p>
893 Structs, unions and enums are explained in a <ref id="structs" name="separate
894 section">, I do only cover them here, because if they are declared with a
895 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
896 name=".SCOPE">/. However, when no name is specified, the behaviour is
897 different: In this case, no new scope will be opened, symbols declared within
898 a struct, union, or enum declaration will then be added to the enclosing scope
902 <sect1>Explicit scope specification<label id="scopesyntax"><p>
904 Accessing symbols from other scopes is possible by using an explicit scope
905 specification, provided that the scope where the symbol lives in has a name.
906 The namespace token (<tt/::/) is used to access other scopes:
914 lda foo::bar ; Access foo in scope bar
917 The only way to deny access to a scope from the outside is to declare a scope
918 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
920 A special syntax is used to specify the global scope: If a symbol or scope is
921 preceded by the namespace token, the global scope is searched:
928 lda #::bar ; Access the global bar (which is 3)
933 <sect1>Scope search order<label id="scopesearch"><p>
935 The assembler searches for a scope in a similar way as for a symbol. First, it
936 looks in the current scope, and then it walks up the enclosing scopes until
939 However, one important thing to note when using explicit scope syntax is, that
940 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
941 used without a preceding definition. This means that in the following
950 lda #foo::bar ; Will load 3, not 2!
957 the reference to the scope <tt/foo/ will use the global scope, and not the
958 local one, because the local one is not visible at the point where it is
961 Things get more complex if a complete chain of scopes is specified:
972 lda #outer::inner::bar ; 1
984 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
985 assembler will first search in the local scope for a scope named <tt/outer/.
986 Since none is found, the enclosing scope (<tt/another/) is checked. There is
987 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
988 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
989 this scope, the assembler looks for a symbol named <tt/bar/.
991 Please note that once the anchor scope is found, all following scopes
992 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
993 assembler will search the scope tree only for the first scope (if it is not
994 anchored in the root scope). Starting from there on, there is no flexibility,
995 so if the scope named <tt/outer/ found by the assembler does not contain a
996 scope named <tt/inner/, this would be an error, even if such a pair does exist
997 (one level up in global scope).
999 Ambiguities that may be introduced by this search algorithm may be removed by
1000 anchoring the scope specification in the global scope. In the example above,
1001 if you want to access the "other" symbol <tt/bar/, you would have to write:
1012 lda #::outer::inner::bar ; 2
1025 <sect>Address sizes and memory models<label id="address-sizes"><p>
1027 <sect1>Address sizes<p>
1029 ca65 assigns each segment and each symbol an address size. This is true, even
1030 if the symbol is not used as an address. You may also think of a value range
1031 of the symbol instead of an address size.
1033 Possible address sizes are:
1036 <item>Zeropage or direct (8 bits)
1037 <item>Absolute (16 bits)
1039 <item>Long (32 bits)
1042 Since the assembler uses default address sizes for the segments and symbols,
1043 it is usually not necessary to override the default behaviour. In cases, where
1044 it is necessary, the following keywords may be used to specify address sizes:
1047 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1048 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1049 <item>FAR for far addressing (24 bits).
1050 <item>LONG or DWORD for long addressing (32 bits).
1054 <sect1>Address sizes of segments<p>
1056 The assembler assigns an address size to each segment. Since the
1057 representation of a label within this segment is "segment start + offset",
1058 labels will inherit the address size of the segment they are declared in.
1060 The address size of a segment may be changed, by using an optional address
1061 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1062 an explanation on how this is done.
1065 <sect1>Address sizes of symbols<p>
1070 <sect1>Memory models<p>
1072 The default address size of a segment depends on the memory model used. Since
1073 labels inherit the address size from the segment they are declared in,
1074 changing the memory model is an easy way to change the address size of many
1080 <sect>Pseudo variables<label id="pseudo-variables"><p>
1082 Pseudo variables are readable in all cases, and in some special cases also
1085 <sect1><tt>*</tt><p>
1087 Reading this pseudo variable will return the program counter at the start
1088 of the current input line.
1090 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1091 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1092 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1095 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1097 Reading this pseudo variable will give a constant integer value that
1098 tells which CPU is currently enabled. It can also tell which instruction
1099 set the CPU is able to translate. The value read from the pseudo variable
1100 should be further examined by using one of the constants defined by the
1101 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1103 It may be used to replace the .IFPxx pseudo instructions or to construct
1104 even more complex expressions.
1110 .if (.cpu .bitand CPU_ISET_65816)
1122 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1124 This builtin pseudo variable is only available in macros. It is replaced by
1125 the actual number of parameters that were given in the macro invocation.
1130 .macro foo arg1, arg2, arg3
1131 .if .paramcount <> 3
1132 .error "Too few parameters for macro foo"
1138 See section <ref id="macros" name="Macros">.
1141 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1143 Reading this pseudo variable will give a constant integer value that
1144 represents the current time in POSIX standard (as seconds since the
1147 It may be used to encode the time of translation somewhere in the created
1153 .dword .time ; Place time here
1157 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1159 Reading this pseudo variable will give the assembler version according to
1160 the following formula:
1162 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1164 It may be used to encode the assembler version or check the assembler for
1165 special features not available with older versions.
1169 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1170 reading the pseudo variable <tt/.VERSION/.
1174 <sect>Pseudo functions<label id="pseudo-functions"><p>
1176 Pseudo functions expect their arguments in parenthesis, and they have a result,
1177 either a string or an expression.
1180 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1182 The function returns the bank byte (that is, bits 16-23) of its argument.
1183 It works identical to the '^' operator.
1185 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1186 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1189 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1191 Builtin function. The function evaluates its argument in braces and yields
1192 "false" if the argument is non blank (there is an argument), and "true" if
1193 there is no argument. The token list that makes up the function argument
1194 may optionally be enclosed in curly braces. This allows the inclusion of
1195 tokens that would otherwise terminate the list (the closing right
1196 parenthesis). The curly braces are not considered part of the list, a list
1197 just consisting of curly braces is considered to be empty.
1199 As an example, the <tt/.IFBLANK/ statement may be replaced by
1207 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1209 Builtin string function. The function allows to concatenate a list of string
1210 constants separated by commas. The result is a string constant that is the
1211 concatenation of all arguments. This function is most useful in macros and
1212 when used together with the <tt/.STRING/ builtin function. The function may
1213 be used in any case where a string constant is expected.
1218 .include .concat ("myheader", ".", "inc")
1221 This is the same as the command
1224 .include "myheader.inc"
1228 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1230 Builtin function. The function evaluates its argument in braces and
1231 yields "true" if the argument is a constant expression (that is, an
1232 expression that yields a constant value at assembly time) and "false"
1233 otherwise. As an example, the .IFCONST statement may be replaced by
1240 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1242 The function returns the high byte (that is, bits 8-15) of its argument.
1243 It works identical to the '>' operator.
1245 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1246 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1249 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1251 The function returns the high word (that is, bits 16-31) of its argument.
1253 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1256 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1258 The function expects a string as its argument, and converts this argument
1259 into an identifier. If the string starts with the current <tt/<ref
1260 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1261 identifier, otherwise it will be converted into a normal identifier.
1266 .macro makelabel arg1, arg2
1267 .ident (.concat (arg1, arg2)):
1270 makelabel "foo", "bar"
1272 .word foobar ; Valid label
1276 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1278 Builtin function. Extracts the left part of a given token list.
1283 .LEFT (<int expr>, <token list>)
1286 The first integer expression gives the number of tokens to extract from
1287 the token list. The second argument is the token list itself. The token
1288 list may optionally be enclosed into curly braces. This allows the
1289 inclusion of tokens that would otherwise terminate the list (the closing
1290 right paren in the given case).
1294 To check in a macro if the given argument has a '#' as first token
1295 (immediate addressing mode), use something like this:
1300 .if (.match (.left (1, {arg}), #))
1302 ; ldax called with immediate operand
1310 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1311 name=".RIGHT"></tt> builtin functions.
1314 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1316 The function returns the low byte (that is, bits 0-7) of its argument.
1317 It works identical to the '<' operator.
1319 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1320 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1323 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1325 The function returns the low word (that is, bits 0-15) of its argument.
1327 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1330 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1332 Builtin function. Matches two token lists against each other. This is
1333 most useful within macros, since macros are not stored as strings, but
1339 .MATCH(<token list #1>, <token list #2>)
1342 Both token list may contain arbitrary tokens with the exception of the
1343 terminator token (comma resp. right parenthesis) and
1350 The token lists may optionally be enclosed into curly braces. This allows
1351 the inclusion of tokens that would otherwise terminate the list (the closing
1352 right paren in the given case). Often a macro parameter is used for any of
1355 Please note that the function does only compare tokens, not token
1356 attributes. So any number is equal to any other number, regardless of the
1357 actual value. The same is true for strings. If you need to compare tokens
1358 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1359 name=".XMATCH"></tt> function.
1363 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1364 while honoring the sign bit. The builtin processor instructions will allow
1365 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1366 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1367 to check for this and print and error for invalid calls.
1372 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1373 .error "Syntax error"
1376 cmp #$80 ; Bit 7 into carry
1377 lsr a ; Shift carry into bit 7
1382 The macro will only accept no arguments, or one argument that must be the
1383 reserved keyword "A".
1385 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1388 <sect1><tt>.MID</tt><label id=".MID"><p>
1390 Builtin function. Takes a starting index, a count and a token list as
1391 arguments. Will return part of the token list.
1396 .MID (<int expr>, <int expr>, <token list>)
1399 The first integer expression gives the starting token in the list (the first
1400 token has index 0). The second integer expression gives the number of tokens
1401 to extract from the token list. The third argument is the token list itself.
1402 The token list may optionally be enclosed into curly braces. This allows the
1403 inclusion of tokens that would otherwise terminate the list (the closing
1404 right paren in the given case).
1408 To check in a macro if the given argument has a '<tt/#/' as first token
1409 (immediate addressing mode), use something like this:
1414 .if (.match (.mid (0, 1, {arg}), #))
1416 ; ldax called with immediate operand
1424 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1425 name=".RIGHT"></tt> builtin functions.
1428 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1430 Builtin function. The function expects an identifier as argument in braces.
1431 The argument is evaluated, and the function yields "true" if the identifier
1432 is a symbol that has already been referenced somewhere in the source file up
1433 to the current position. Otherwise the function yields false. As an example,
1434 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1440 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1443 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1445 Builtin function. Extracts the right part of a given token list.
1450 .RIGHT (<int expr>, <token list>)
1453 The first integer expression gives the number of tokens to extract from the
1454 token list. The second argument is the token list itself. The token list
1455 may optionally be enclosed into curly braces. This allows the inclusion of
1456 tokens that would otherwise terminate the list (the closing right paren in
1459 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1460 name=".MID"></tt> builtin functions.
1463 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1465 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1466 argument can be a struct/union, a struct member, a procedure, or a label. In
1467 case of a procedure or label, its size is defined by the amount of data
1468 placed in the segment where the label is relative to. If a line of code
1469 switches segments (for example in a macro) data placed in other segments
1470 does not count for the size.
1472 Please note that a symbol or scope must exist, before it is used together with
1473 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1474 A scope has preference over a symbol with the same name, so if the last part
1475 of a name represents both, a scope and a symbol, the scope is chosen over the
1478 After the following code:
1481 .struct Point ; Struct size = 4
1486 P: .tag Point ; Declare a point
1487 @P: .tag Point ; Declare another point
1499 .data ; Segment switch!!!
1505 <tag><tt/.sizeof(Point)/</tag>
1506 will have the value 4, because this is the size of struct <tt/Point/.
1508 <tag><tt/.sizeof(Point::xcoord)/</tag>
1509 will have the value 2, because this is the size of the member <tt/xcoord/
1510 in struct <tt/Point/.
1512 <tag><tt/.sizeof(P)/</tag>
1513 will have the value 4, this is the size of the data declared on the same
1514 source line as the label <tt/P/, which is in the same segment that <tt/P/
1517 <tag><tt/.sizeof(@P)/</tag>
1518 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1519 does also work for cheap local symbols.
1521 <tag><tt/.sizeof(Code)/</tag>
1522 will have the value 3, since this is amount of data emitted into the code
1523 segment, the segment that was active when <tt/Code/ was entered. Note that
1524 this value includes the amount of data emitted in child scopes (in this
1525 case <tt/Code::Inner/).
1527 <tag><tt/.sizeof(Code::Inner)/</tag>
1528 will have the value 1 as expected.
1530 <tag><tt/.sizeof(Data)/</tag>
1531 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1532 the segment is switched after entry, this data is emitted into another
1537 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1539 Builtin function. The function accepts a string and an index as
1540 arguments and returns the value of the character at the given position
1541 as an integer value. The index is zero based.
1547 ; Check if the argument string starts with '#'
1548 .if (.strat (Arg, 0) = '#')
1555 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1557 Builtin function. It expects a format string as first argument. The number
1558 and type of the following arguments depend on the format string. The format
1559 string is similar to the one of the C <tt/printf/ function. Missing things
1560 are: Length modifiers, variable width.
1562 The result of the function is a string.
1569 ; Generate an identifier:
1570 .ident (.sprintf ("%s%03d", "label", num)):
1574 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1576 Builtin function. The function accepts an argument in braces and converts
1577 this argument into a string constant. The argument may be an identifier, or
1578 a constant numeric value.
1580 Since you can use a string in the first place, the use of the function may
1581 not be obvious. However, it is useful in macros, or more complex setups.
1586 ; Emulate other assemblers:
1588 .segment .string(name)
1593 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1595 Builtin function. The function accepts a string argument in braces and
1596 evaluates to the length of the string.
1600 The following macro encodes a string as a pascal style string with
1601 a leading length byte.
1605 .byte .strlen(Arg), Arg
1610 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1612 Builtin function. The function accepts a token list in braces. The function
1613 result is the number of tokens given as argument. The token list may
1614 optionally be enclosed into curly braces which are not considered part of
1615 the list and not counted. Enclosement in curly braces allows the inclusion
1616 of tokens that would otherwise terminate the list (the closing right paren
1621 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1622 with the normal 6502 instructions). To translate it into two separate 8 bit
1623 load instructions, the '#' token has to get stripped from the argument:
1627 .if (.match (.mid (0, 1, {arg}), #))
1628 ; ldax called with immediate operand
1629 lda #<(.right (.tcount ({arg})-1, {arg}))
1630 ldx #>(.right (.tcount ({arg})-1, {arg}))
1638 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1640 Builtin function. Matches two token lists against each other. This is
1641 most useful within macros, since macros are not stored as strings, but
1647 .XMATCH(<token list #1>, <token list #2>)
1650 Both token list may contain arbitrary tokens with the exception of the
1651 terminator token (comma resp. right parenthesis) and
1658 The token lists may optionally be enclosed into curly braces. This allows
1659 the inclusion of tokens that would otherwise terminate the list (the closing
1660 right paren in the given case). Often a macro parameter is used for any of
1663 The function compares tokens <em/and/ token values. If you need a function
1664 that just compares the type of tokens, have a look at the <tt><ref
1665 id=".MATCH" name=".MATCH"></tt> function.
1667 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1671 <sect>Control commands<label id="control-commands"><p>
1673 Here's a list of all control commands and a description, what they do:
1676 <sect1><tt>.A16</tt><label id=".A16"><p>
1678 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1680 Note: This command will not emit any code, it will tell the assembler to
1681 create 16 bit operands for immediate accumulator addressing mode.
1683 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1686 <sect1><tt>.A8</tt><label id=".A8"><p>
1688 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1690 Note: This command will not emit any code, it will tell the assembler to
1691 create 8 bit operands for immediate accu addressing mode.
1693 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1696 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1698 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1699 may be used for better readability if the data words are address values. In
1700 65816 mode, the address is forced to be 16 bit wide to fit into the current
1701 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1702 must be followed by a sequence of (not necessarily constant) expressions.
1707 .addr $0D00, $AF13, _Clear
1710 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1714 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1716 Align data to a given boundary. The command expects a constant integer
1717 argument that must be a power of two, plus an optional second argument
1718 in byte range. If there is a second argument, it is used as fill value,
1719 otherwise the value defined in the linker configuration file is used
1720 (the default for this value is zero).
1722 Since alignment depends on the base address of the module, you must
1723 give the same (or a greater) alignment for the segment when linking.
1724 The linker will give you a warning, if you don't do that.
1733 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1735 Define a string with a trailing zero.
1740 Msg: .asciiz "Hello world"
1743 This will put the string "Hello world" followed by a binary zero into
1744 the current segment. There may be more strings separated by commas, but
1745 the binary zero is only appended once (after the last one).
1748 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1750 Add an assertion. The command is followed by an expression, an action
1751 specifier, and an optional message that is output in case the assertion
1752 fails. If no message was given, the string "Assertion failed" is used. The
1753 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
1754 <tt/lderror/. In the former two cases, the assertion is evaluated by the
1755 assembler if possible, and in any case, it's also passed to the linker in
1756 the object file (if one is generated). The linker will then evaluate the
1757 expression when segment placement has been done.
1762 .assert * = $8000, error, "Code not at $8000"
1765 The example assertion will check that the current location is at $8000,
1766 when the output file is written, and abort with an error if this is not
1767 the case. More complex expressions are possible. The action specifier
1768 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1769 an error message. In the latter case, generation of the output file is
1770 suppressed in both the assembler and linker.
1773 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1775 Is followed by a plus or a minus character. When switched on (using a
1776 +), undefined symbols are automatically marked as import instead of
1777 giving errors. When switched off (which is the default so this does not
1778 make much sense), this does not happen and an error message is
1779 displayed. The state of the autoimport flag is evaluated when the
1780 complete source was translated, before outputting actual code, so it is
1781 <em/not/ possible to switch this feature on or off for separate sections
1782 of code. The last setting is used for all symbols.
1784 You should probably not use this switch because it delays error
1785 messages about undefined symbols until the link stage. The cc65
1786 compiler (which is supposed to produce correct assembler code in all
1787 circumstances, something which is not true for most assembler
1788 programmers) will insert this command to avoid importing each and every
1789 routine from the runtime library.
1794 .autoimport + ; Switch on auto import
1797 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
1799 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
1800 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
1801 the operator '^' prepended to each expression in its list.
1806 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
1808 TableLookupLo: .lobytes MyTable
1809 TableLookupHi: .hibytes MyTable
1810 TableLookupBank: .bankbytes MyTable
1813 which is equivalent to
1816 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
1817 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
1818 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
1821 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
1822 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
1823 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
1826 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1828 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1829 so this is a shortcut for
1835 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1838 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1840 Define byte sized data. Must be followed by a sequence of (byte ranged)
1841 expressions or strings.
1847 .byt "world", $0D, $00
1851 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1853 Switch on or off case sensitivity on identifiers. The default is off
1854 (that is, identifiers are case sensitive), but may be changed by the
1855 -i switch on the command line.
1856 The command must be followed by a '+' or '-' character to switch the
1857 option on or off respectively.
1862 .case - ; Identifiers are not case sensitive
1866 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1868 Apply a custom mapping for characters. The command is followed by two
1869 numbers in the range 1..255. The first one is the index of the source
1870 character, the second one is the mapping. The mapping applies to all
1871 character and string constants when they generate output, and overrides
1872 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1873 command line switch.
1878 .charmap $41, $61 ; Map 'A' to 'a'
1882 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1884 Switch to the CODE segment. The name of the CODE segment is always
1885 "CODE", so this is a shortcut for
1891 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1894 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1896 Export a symbol and mark it in a special way. The linker is able to build
1897 tables of all such symbols. This may be used to automatically create a list
1898 of functions needed to initialize linked library modules.
1900 Note: The linker has a feature to build a table of marked routines, but it
1901 is your code that must call these routines, so just declaring a symbol with
1902 <tt/.CONDES/ does nothing by itself.
1904 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1905 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1906 is implied by <tt/.CONDES/.
1908 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1909 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1910 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1911 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1912 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1913 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
1914 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
1916 After the type, an optional priority may be specified. Higher numeric values
1917 mean higher priority. If no priority is given, the default priority of 7 is
1918 used. Be careful when assigning priorities to your own module constructors
1919 so they won't interfere with the ones in the cc65 library.
1924 .condes ModuleInit, constructor
1925 .condes ModInit, 0, 16
1928 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1929 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1930 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
1931 name="Module constructors/destructors"> explaining the feature in more
1935 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1937 Export a symbol and mark it as a module constructor. This may be used
1938 together with the linker to build a table of constructor subroutines that
1939 are called by the startup code.
1941 Note: The linker has a feature to build a table of marked routines, but it
1942 is your code that must call these routines, so just declaring a symbol as
1943 constructor does nothing by itself.
1945 A constructor is always exported as an absolute (16 bit) symbol. You don't
1946 need to use an additional <tt/.export/ statement, this is implied by
1947 <tt/.constructor/. It may have an optional priority that is separated by a
1948 comma. Higher numeric values mean a higher priority. If no priority is
1949 given, the default priority of 7 is used. Be careful when assigning
1950 priorities to your own module constructors so they won't interfere with the
1951 ones in the cc65 library.
1956 .constructor ModuleInit
1957 .constructor ModInit, 16
1960 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1961 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1962 <ref id="condes" name="Module constructors/destructors"> explaining the
1963 feature in more detail.
1966 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1968 Switch to the DATA segment. The name of the DATA segment is always
1969 "DATA", so this is a shortcut for
1975 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1978 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1980 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1981 create word sized data in native 65XX format). Must be followed by a
1982 sequence of (word ranged) expressions.
1990 This will emit the bytes
1996 into the current segment in that order.
1999 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2001 Switch on or off debug info generation. The default is off (that is,
2002 the object file will not contain debug infos), but may be changed by the
2003 -g switch on the command line.
2004 The command must be followed by a '+' or '-' character to switch the
2005 option on or off respectively.
2010 .debuginfo + ; Generate debug info
2014 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2016 Start a define style macro definition. The command is followed by an
2017 identifier (the macro name) and optionally by a list of formal arguments
2019 See section <ref id="macros" name="Macros">.
2022 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2024 Builtin function. The function expects an identifier as argument in braces.
2025 The argument is evaluated, and the function yields "true" if the identifier
2026 is a symbol that is already defined somewhere in the source file up to the
2027 current position. Otherwise the function yields false. As an example, the
2028 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2035 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2037 Export a symbol and mark it as a module destructor. This may be used
2038 together with the linker to build a table of destructor subroutines that
2039 are called by the startup code.
2041 Note: The linker has a feature to build a table of marked routines, but it
2042 is your code that must call these routines, so just declaring a symbol as
2043 constructor does nothing by itself.
2045 A destructor is always exported as an absolute (16 bit) symbol. You don't
2046 need to use an additional <tt/.export/ statement, this is implied by
2047 <tt/.destructor/. It may have an optional priority that is separated by a
2048 comma. Higher numerical values mean a higher priority. If no priority is
2049 given, the default priority of 7 is used. Be careful when assigning
2050 priorities to your own module destructors so they won't interfere with the
2051 ones in the cc65 library.
2056 .destructor ModuleDone
2057 .destructor ModDone, 16
2060 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2061 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2062 section <ref id="condes" name="Module constructors/destructors"> explaining
2063 the feature in more detail.
2066 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2068 Define dword sized data (4 bytes) Must be followed by a sequence of
2074 .dword $12344512, $12FA489
2078 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2080 Conditional assembly: Reverse the current condition.
2083 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2085 Conditional assembly: Reverse current condition and test a new one.
2088 <sect1><tt>.END</tt><label id=".END"><p>
2090 Forced end of assembly. Assembly stops at this point, even if the command
2091 is read from an include file.
2094 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2096 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2099 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2101 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2102 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2105 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2107 End of macro definition (see section <ref id="macros" name="Macros">).
2110 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2112 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2115 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2117 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2120 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2122 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2125 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2127 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2128 command and the separate section named <ref id="structs" name=""Structs
2132 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2134 Start an enumeration. This directive is very similar to the C <tt/enum/
2135 keyword. If a name is given, a new scope is created for the enumeration,
2136 otherwise the enumeration members are placed in the enclosing scope.
2138 In the enumeration body, symbols are declared. The first symbol has a value
2139 of zero, and each following symbol will get the value of the preceding plus
2140 one. This behaviour may be overridden by an explicit assignment. Two symbols
2141 may have the same value.
2153 Above example will create a new scope named <tt/errorcodes/ with three
2154 symbols in it that get the values 0, 1 and 2 respectively. Another way
2155 to write this would have been:
2165 Please note that explicit scoping must be used to access the identifiers:
2168 .word errorcodes::no_error
2171 A more complex example:
2180 EWOULDBLOCK = EAGAIN
2184 In this example, the enumeration does not have a name, which means that the
2185 members will be visible in the enclosing scope and can be used in this scope
2186 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2187 The value for the following members is incremented by one, so <tt/EOK/ would
2188 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2189 override for the value using an already defined symbol.
2192 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2194 Force an assembly error. The assembler will output an error message
2195 preceded by "User error" and will <em/not/ produce an object file.
2197 This command may be used to check for initial conditions that must be
2198 set before assembling a source file.
2208 .error "Must define foo or bar!"
2212 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2213 id=".OUT" name=".OUT"></tt> directives.
2216 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2218 Abort a macro expansion immediately. This command is often useful in
2219 recursive macros. See separate section <ref id="macros" name="Macros">.
2222 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2224 Make symbols accessible from other modules. Must be followed by a comma
2225 separated list of symbols to export, with each one optionally followed by an
2226 address specification and (also optional) an assignment. Using an additional
2227 assignment in the export statement allows to define and export a symbol in
2228 one statement. The default is to export the symbol with the address size it
2229 actually has. The assembler will issue a warning, if the symbol is exported
2230 with an address size smaller than the actual address size.
2237 .export foobar: far = foo * bar
2238 .export baz := foobar, zap: far = baz - bar
2241 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2244 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2247 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2249 Make symbols accessible from other modules. Must be followed by a comma
2250 separated list of symbols to export. The exported symbols are explicitly
2251 marked as zero page symbols. An assignment may be included in the
2252 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2259 .exportzp baz := $02
2262 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2265 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2267 Define far (24 bit) address data. The command must be followed by a
2268 sequence of (not necessarily constant) expressions.
2273 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2276 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2279 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2281 This directive may be used to enable one or more compatibility features
2282 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2283 possible, it may be useful when porting sources written for other
2284 assemblers. There is no way to switch a feature off, once you have
2285 enabled it, so using
2291 will enable the feature until end of assembly is reached.
2293 The following features are available:
2297 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2299 Accept the at character (`@') as a valid character in identifiers. The
2300 at character is not allowed to start an identifier, even with this
2303 <tag><tt>c_comments</tt></tag>
2305 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2306 comment terminators. Note that C comments may not be nested. There's also a
2307 pitfall when using C like comments: All statements must be terminated by
2308 "end-of-line". Using C like comments, it is possible to hide the newline,
2309 which results in error messages. See the following non working example:
2312 lda #$00 /* This comment hides the newline
2316 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2318 Accept the dollar sign (`$') as a valid character in identifiers. The
2319 dollar character is not allowed to start an identifier, even with this
2322 <tag><tt>dollar_is_pc</tt></tag>
2324 The dollar sign may be used as an alias for the star (`*'), which
2325 gives the value of the current PC in expressions.
2326 Note: Assignment to the pseudo variable is not allowed.
2328 <tag><tt>labels_without_colons</tt></tag>
2330 Allow labels without a trailing colon. These labels are only accepted,
2331 if they start at the beginning of a line (no leading white space).
2333 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2335 Accept the dot (`.') as the first character of an identifier. This may be
2336 used for example to create macro names that start with a dot emulating
2337 control directives of other assemblers. Note however, that none of the
2338 reserved keywords built into the assembler, that starts with a dot, may be
2339 overridden. When using this feature, you may also get into trouble if
2340 later versions of the assembler define new keywords starting with a dot.
2342 <tag><tt>loose_char_term</tt></tag>
2344 Accept single quotes as well as double quotes as terminators for char
2347 <tag><tt>loose_string_term</tt></tag>
2349 Accept single quotes as well as double quotes as terminators for string
2352 <tag><tt>missing_char_term</tt></tag>
2354 Accept single quoted character constants where the terminating quote is
2359 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2360 loose_string_term/, since in this case the input would be ambiguous.
2362 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2364 This feature makes relocatable/absolute mode local to the current segment.
2365 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2366 effect will only enable absolute mode for the current segment. Dito for
2367 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2369 <tag><tt>pc_assignment</tt></tag>
2371 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2372 is enabled). Such an assignment is handled identical to the <tt><ref
2373 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2374 removing the lines with the assignments may also be an option when porting
2375 code written for older assemblers).
2377 <tag><tt>ubiquitous_idents</tt></tag>
2379 Allow the use of instructions names as names for macros and symbols. This
2380 makes it possible to "overload" instructions by defining a macro with the
2381 same name. This does also make it possible to introduce hard to find errors
2382 in your code, so be careful!
2386 It is also possible to specify features on the command line using the
2387 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2388 This is useful when translating sources written for older assemblers, when
2389 you don't want to change the source code.
2391 As an example, to translate sources written for Andre Fachats xa65
2392 assembler, the features
2395 labels_without_colons, pc_assignment, loose_char_term
2398 may be helpful. They do not make ca65 completely compatible, so you may not
2399 be able to translate the sources without changes, even when enabling these
2400 features. However, I have found several sources that translate without
2401 problems when enabling these features on the command line.
2404 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2406 Insert an option string into the object file. There are two forms of
2407 this command, one specifies the option by a keyword, the second
2408 specifies it as a number. Since usage of the second one needs knowledge
2409 of the internal encoding, its use is not recommended and I will only
2410 describe the first form here.
2412 The command is followed by one of the keywords
2420 a comma and a string. The option is written into the object file
2421 together with the string value. This is currently unidirectional and
2422 there is no way to actually use these options once they are in the
2428 .fileopt comment, "Code stolen from my brother"
2429 .fileopt compiler, "BASIC 2.0"
2430 .fopt author, "J. R. User"
2434 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2436 Import an absolute symbol from another module. The command is followed by a
2437 comma separated list of symbols to import. The command is similar to <tt>
2438 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2439 written to the generated object file, even if the symbol is never referenced
2440 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2441 references for unused symbols).
2446 .forceimport needthisone, needthistoo
2449 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2452 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2454 Declare symbols as global. Must be followed by a comma separated list of
2455 symbols to declare. Symbols from the list, that are defined somewhere in the
2456 source, are exported, all others are imported. Additional <tt><ref
2457 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2458 name=".EXPORT"></tt> commands for the same symbol are allowed.
2467 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2469 Declare symbols as global. Must be followed by a comma separated list of
2470 symbols to declare. Symbols from the list, that are defined somewhere in the
2471 source, are exported, all others are imported. Additional <tt><ref
2472 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2473 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2474 in the list are explicitly marked as zero page symbols.
2482 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2484 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2485 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2486 the operator '>' prepended to each expression in its list.
2491 .lobytes $1234, $2345, $3456, $4567
2492 .hibytes $fedc, $edcb, $dcba, $cba9
2495 which is equivalent to
2498 .byte $34, $45, $56, $67
2499 .byte $fe, $ed, $dc, $cb
2505 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2507 TableLookupLo: .lobytes MyTable
2508 TableLookupHi: .hibytes MyTable
2511 which is equivalent to
2514 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2515 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2518 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2519 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2520 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2523 <sect1><tt>.I16</tt><label id=".I16"><p>
2525 Valid only in 65816 mode. Switch the index registers to 16 bit.
2527 Note: This command will not emit any code, it will tell the assembler to
2528 create 16 bit operands for immediate operands.
2530 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2531 name=".SMART"></tt> commands.
2534 <sect1><tt>.I8</tt><label id=".I8"><p>
2536 Valid only in 65816 mode. Switch the index registers to 8 bit.
2538 Note: This command will not emit any code, it will tell the assembler to
2539 create 8 bit operands for immediate operands.
2541 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2542 name=".SMART"></tt> commands.
2545 <sect1><tt>.IF</tt><label id=".IF"><p>
2547 Conditional assembly: Evaluate an expression and switch assembler output
2548 on or off depending on the expression. The expression must be a constant
2549 expression, that is, all operands must be defined.
2551 A expression value of zero evaluates to FALSE, any other value evaluates
2555 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2557 Conditional assembly: Check if there are any remaining tokens in this line,
2558 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2559 condition is not true, further lines are not assembled until an <tt><ref
2560 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2561 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2563 This command is often used to check if a macro parameter was given. Since an
2564 empty macro parameter will evaluate to nothing, the condition will evaluate
2565 to FALSE if an empty parameter was given.
2579 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2582 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2584 Conditional assembly: Evaluate an expression and switch assembler output
2585 on or off depending on the constness of the expression.
2587 A const expression evaluates to to TRUE, a non const expression (one
2588 containing an imported or currently undefined symbol) evaluates to
2591 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2594 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2596 Conditional assembly: Check if a symbol is defined. Must be followed by
2597 a symbol name. The condition is true if the the given symbol is already
2598 defined, and false otherwise.
2600 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2603 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2605 Conditional assembly: Check if there are any remaining tokens in this line,
2606 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2607 condition is not true, further lines are not assembled until an <tt><ref
2608 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2609 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2611 This command is often used to check if a macro parameter was given.
2612 Since an empty macro parameter will evaluate to nothing, the condition
2613 will evaluate to FALSE if an empty parameter was given.
2626 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2629 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2631 Conditional assembly: Check if a symbol is defined. Must be followed by
2632 a symbol name. The condition is true if the the given symbol is not
2633 defined, and false otherwise.
2635 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2638 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2640 Conditional assembly: Check if a symbol is referenced. Must be followed
2641 by a symbol name. The condition is true if if the the given symbol was
2642 not referenced before, and false otherwise.
2644 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2647 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2649 Conditional assembly: Check if the assembler is currently in 6502 mode
2650 (see <tt><ref id=".P02" name=".P02"></tt> command).
2653 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2655 Conditional assembly: Check if the assembler is currently in 65816 mode
2656 (see <tt><ref id=".P816" name=".P816"></tt> command).
2659 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2661 Conditional assembly: Check if the assembler is currently in 65C02 mode
2662 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2665 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2667 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2668 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2671 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2673 Conditional assembly: Check if a symbol is referenced. Must be followed
2674 by a symbol name. The condition is true if if the the given symbol was
2675 referenced before, and false otherwise.
2677 This command may be used to build subroutine libraries in include files
2678 (you may use separate object modules for this purpose too).
2683 .ifref ToHex ; If someone used this subroutine
2684 ToHex: tay ; Define subroutine
2690 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2693 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2695 Import a symbol from another module. The command is followed by a comma
2696 separated list of symbols to import, with each one optionally followed by
2697 an address specification.
2703 .import bar: zeropage
2706 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2709 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2711 Import a symbol from another module. The command is followed by a comma
2712 separated list of symbols to import. The symbols are explicitly imported
2713 as zero page symbols (that is, symbols with values in byte range).
2721 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2724 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2726 Include a file as binary data. The command expects a string argument
2727 that is the name of a file to include literally in the current segment.
2728 In addition to that, a start offset and a size value may be specified,
2729 separated by commas. If no size is specified, all of the file from the
2730 start offset to end-of-file is used. If no start position is specified
2731 either, zero is assumed (which means that the whole file is inserted).
2736 ; Include whole file
2737 .incbin "sprites.dat"
2739 ; Include file starting at offset 256
2740 .incbin "music.dat", $100
2742 ; Read 100 bytes starting at offset 200
2743 .incbin "graphics.dat", 200, 100
2747 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2749 Include another file. Include files may be nested up to a depth of 16.
2758 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
2760 Export a symbol and mark it as an interruptor. This may be used together
2761 with the linker to build a table of interruptor subroutines that are called
2764 Note: The linker has a feature to build a table of marked routines, but it
2765 is your code that must call these routines, so just declaring a symbol as
2766 interruptor does nothing by itself.
2768 An interruptor is always exported as an absolute (16 bit) symbol. You don't
2769 need to use an additional <tt/.export/ statement, this is implied by
2770 <tt/.interruptor/. It may have an optional priority that is separated by a
2771 comma. Higher numeric values mean a higher priority. If no priority is
2772 given, the default priority of 7 is used. Be careful when assigning
2773 priorities to your own module constructors so they won't interfere with the
2774 ones in the cc65 library.
2779 .interruptor IrqHandler
2780 .interruptor Handler, 16
2783 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
2784 section <ref id="condes" name="Module constructors/destructors"> explaining
2785 the feature in more detail.
2788 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2790 Switch on or off line continuations using the backslash character
2791 before a newline. The option is off by default.
2792 Note: Line continuations do not work in a comment. A backslash at the
2793 end of a comment is treated as part of the comment and does not trigger
2795 The command must be followed by a '+' or '-' character to switch the
2796 option on or off respectively.
2801 .linecont + ; Allow line continuations
2804 #$20 ; This is legal now
2808 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2810 Enable output to the listing. The command must be followed by a boolean
2811 switch ("on", "off", "+" or "-") and will enable or disable listing
2813 The option has no effect if the listing is not enabled by the command line
2814 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2815 to the listing file, if the counter is greater than zero, and suppressed if
2816 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2822 .list on ; Enable listing output
2826 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2828 Set, how many bytes are shown in the listing for one source line. The
2829 default is 12, so the listing will show only the first 12 bytes for any
2830 source line that generates more than 12 bytes of code or data.
2831 The directive needs an argument, which is either "unlimited", or an
2832 integer constant in the range 4..255.
2837 .listbytes unlimited ; List all bytes
2838 .listbytes 12 ; List the first 12 bytes
2839 .incbin "data.bin" ; Include large binary file
2843 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
2845 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
2846 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2847 the operator '<' prepended to each expression in its list.
2852 .lobytes $1234, $2345, $3456, $4567
2853 .hibytes $fedc, $edcb, $dcba, $cba9
2856 which is equivalent to
2859 .byte $34, $45, $56, $67
2860 .byte $fe, $ed, $dc, $cb
2866 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2868 TableLookupLo: .lobytes MyTable
2869 TableLookupHi: .hibytes MyTable
2872 which is equivalent to
2875 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2876 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2879 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2880 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2881 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2884 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2886 This command may only be used inside a macro definition. It declares a
2887 list of identifiers as local to the macro expansion.
2889 A problem when using macros are labels: Since they don't change their name,
2890 you get a "duplicate symbol" error if the macro is expanded the second time.
2891 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2892 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2895 Some other assemblers start a new lexical block inside a macro expansion.
2896 This has some drawbacks however, since that will not allow <em/any/ symbol
2897 to be visible outside a macro, a feature that is sometimes useful. The
2898 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2899 to address the problem.
2901 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2905 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2907 Defines the character that start "cheap" local labels. You may use one
2908 of '@' and '?' as start character. The default is '@'.
2910 Cheap local labels are labels that are visible only between two non
2911 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2912 using explicit lexical nesting.
2919 Clear: lda #$00 ; Global label
2920 ?Loop: sta Mem,y ; Local label
2924 Sub: ... ; New global label
2925 bne ?Loop ; ERROR: Unknown identifier!
2929 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2931 Insert a predefined macro package. The command is followed by an
2932 identifier specifying the macro package to insert. Available macro
2936 atari Defines the scrcode macro.
2937 cbm Defines the scrcode macro.
2938 cpu Defines constants for the .CPU variable.
2939 generic Defines generic macros like add and sub.
2940 longbranch Defines conditional long jump macros.
2943 Including a macro package twice, or including a macro package that
2944 redefines already existing macros will lead to an error.
2949 .macpack longbranch ; Include macro package
2951 cmp #$20 ; Set condition codes
2952 jne Label ; Jump long on condition
2955 Macro packages are explained in more detail in section <ref
2956 id="macropackages" name="Macro packages">.
2959 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2961 Start a classic macro definition. The command is followed by an identifier
2962 (the macro name) and optionally by a comma separated list of identifiers
2963 that are macro parameters.
2965 See section <ref id="macros" name="Macros">.
2968 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2970 Start a section of absolute code. The command is followed by a constant
2971 expression that gives the new PC counter location for which the code is
2972 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2975 By default, absolute/relocatable mode is global (valid even when switching
2976 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
2977 it can be made segment local.
2979 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
2980 code at a specific address is the job of the linker, not the assembler, so
2981 there is usually no reason to assemble code to a specific address.
2986 .org $7FF ; Emit code starting at $7FF
2990 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2992 Output a string to the console without producing an error. This command
2993 is similar to <tt/.ERROR/, however, it does not force an assembler error
2994 that prevents the creation of an object file.
2999 .out "This code was written by the codebuster(tm)"
3002 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
3003 id=".ERROR" name=".ERROR"></tt> directives.
3006 <sect1><tt>.P02</tt><label id=".P02"><p>
3008 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3009 instructions. This is the default if not overridden by the
3010 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3012 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3013 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3016 <sect1><tt>.P816</tt><label id=".P816"><p>
3018 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3019 6502 instruction sets.
3021 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3022 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3025 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3027 Set the page length for the listing. Must be followed by an integer
3028 constant. The value may be "unlimited", or in the range 32 to 127. The
3029 statement has no effect if no listing is generated. The default value is -1
3030 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3031 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3032 after assembly is complete, you cannot use multiple line lengths with one
3033 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3038 .pagelength 66 ; Use 66 lines per listing page
3040 .pagelength unlimited ; Unlimited page length
3044 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3046 Enable the 65C02 instructions set. This instruction set includes all
3047 6502 and 65SC02 instructions.
3049 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3050 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3053 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3055 Pop the last pushed segment from the stack, and set it.
3057 This command will switch back to the segment that was last pushed onto the
3058 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3059 command, and remove this entry from the stack.
3061 The assembler will print an error message if the segment stack is empty
3062 when this command is issued.
3064 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3067 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3069 Start a nested lexical level with the given name and adds a symbol with this
3070 name to the enclosing scope. All new symbols from now on are in the local
3071 lexical level and are accessible from outside only via <ref id="scopesyntax"
3072 name="explicit scope specification">. Symbols defined outside this local
3073 level may be accessed as long as their names are not used for new symbols
3074 inside the level. Symbols names in other lexical levels do not clash, so you
3075 may use the same names for identifiers. The lexical level ends when the
3076 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3077 may be nested up to a depth of 16 (this is an artificial limit to protect
3078 against errors in the source).
3080 Note: Macro names are always in the global level and in a separate name
3081 space. There is no special reason for this, it's just that I've never
3082 had any need for local macro definitions.
3087 .proc Clear ; Define Clear subroutine, start new level
3089 L1: sta Mem,y ; L1 is local and does not cause a
3090 ; duplicate symbol error if used in other
3093 bne L1 ; Reference local symbol
3095 .endproc ; Leave lexical level
3098 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3102 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3104 Enable the 65SC02 instructions set. This instruction set includes all
3107 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3108 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3111 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3113 Push the currently active segment onto a stack. The entries on the stack
3114 include the name of the segment and the segment type. The stack has a size
3117 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3118 to switch to another segment and to restore the old segment later, without
3119 even knowing the name and type of the current segment.
3121 The assembler will print an error message if the segment stack is already
3122 full, when this command is issued.
3124 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3127 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3129 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3130 name=".ORG"></tt> command.
3133 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3135 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3136 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3137 a constant expression that tells how many times the commands in the body
3138 should get repeated. Optionally, a comma and an identifier may be specified.
3139 If this identifier is found in the body of the repeat statement, it is
3140 replaced by the current repeat count (starting with zero for the first time
3141 the body is repeated).
3143 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3144 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3145 level will be used, not the one from the outer level.
3149 The following macro will emit a string that is "encrypted" in that all
3150 characters of the string are XORed by the value $55.
3154 .repeat .strlen(Arg), I
3155 .byte .strat(Arg, I) ^ $55
3160 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3163 <sect1><tt>.RES</tt><label id=".RES"><p>
3165 Reserve storage. The command is followed by one or two constant
3166 expressions. The first one is mandatory and defines, how many bytes of
3167 storage should be defined. The second, optional expression must by a
3168 constant byte value that will be used as value of the data. If there
3169 is no fill value given, the linker will use the value defined in the
3170 linker configuration file (default: zero).
3175 ; Reserve 12 bytes of memory with value $AA
3180 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3182 Switch to the RODATA segment. The name of the RODATA segment is always
3183 "RODATA", so this is a shortcut for
3189 The RODATA segment is a segment that is used by the compiler for
3190 readonly data like string constants.
3192 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3195 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3197 Start a nested lexical level with the given name. All new symbols from now
3198 on are in the local lexical level and are accessible from outside only via
3199 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3200 outside this local level may be accessed as long as their names are not used
3201 for new symbols inside the level. Symbols names in other lexical levels do
3202 not clash, so you may use the same names for identifiers. The lexical level
3203 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3204 read. Lexical levels may be nested up to a depth of 16 (this is an
3205 artificial limit to protect against errors in the source).
3207 Note: Macro names are always in the global level and in a separate name
3208 space. There is no special reason for this, it's just that I've never
3209 had any need for local macro definitions.
3214 .scope Error ; Start new scope named Error
3216 File = 1 ; File error
3217 Parse = 2 ; Parse error
3218 .endscope ; Close lexical level
3221 lda #Error::File ; Use symbol from scope Error
3224 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3228 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3230 Switch to another segment. Code and data is always emitted into a
3231 segment, that is, a named section of data. The default segment is
3232 "CODE". There may be up to 254 different segments per object file
3233 (and up to 65534 per executable). There are shortcut commands for
3234 the most common segments ("CODE", "DATA" and "BSS").
3236 The command is followed by a string containing the segment name (there are
3237 some constraints for the name - as a rule of thumb use only those segment
3238 names that would also be valid identifiers). There may also be an optional
3239 address size separated by a colon. See the section covering <tt/<ref
3240 id="address-sizes" name="address sizes">/ for more information.
3242 The default address size for a segment depends on the memory model specified
3243 on the command line. The default is "absolute", which means that you don't
3244 have to use an address size modifier in most cases.
3246 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3247 That is, the segment will reside somewhere in core memory outside the zero
3248 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3249 page and direct (short) addressing is possible for data in this segment.
3251 Beware: Only labels in a segment with the zeropage attribute are marked
3252 as reachable by short addressing. The `*' (PC counter) operator will
3253 work as in other segments and will create absolute variable values.
3255 Please note that a segment cannot have two different address sizes. A
3256 segment specified as zeropage cannot be declared as being absolute later.
3261 .segment "ROM2" ; Switch to ROM2 segment
3262 .segment "ZP2": zeropage ; New direct segment
3263 .segment "ZP2" ; Ok, will use last attribute
3264 .segment "ZP2": absolute ; Error, redecl mismatch
3267 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3268 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3269 id=".RODATA" name=".RODATA"></tt>
3272 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3274 Switch the CPU instruction set. The command is followed by a string that
3275 specifies the CPU. Possible values are those that can also be supplied to
3276 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3277 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3278 note that support for the sunplus CPU is not available in the freeware
3279 version, because the instruction set of the sunplus CPU is "proprietary
3282 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3283 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3284 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3285 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3286 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3287 <tt><ref id=".P02" name=".P02"></tt>,
3288 <tt><ref id=".P816" name=".P816"></tt>,
3289 <tt><ref id=".PC02" name=".PC02"></tt>,
3290 <tt><ref id=".PSC02" name=".PSC02"></tt>
3293 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3295 Switch on or off smart mode. The command must be followed by a '+' or '-'
3296 character to switch the option on or off respectively. The default is off
3297 (that is, the assembler doesn't try to be smart), but this default may be
3298 changed by the -s switch on the command line.
3300 In smart mode the assembler will do the following:
3303 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3304 and update the operand sizes accordingly. If the operand of such an
3305 instruction cannot be evaluated by the assembler (for example, because
3306 the operand is an imported symbol), a warning is issued. Beware: Since
3307 the assembler cannot trace the execution flow this may lead to false
3308 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3309 instructions to tell the assembler about the current settings.
3310 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3311 used within a procedure declared as <tt/far/, or if the procedure has
3312 no explicit address specification, but it is <tt/far/ because of the
3320 .smart - ; Stop being smart
3323 See: <tt><ref id=".A16" name=".A16"></tt>,
3324 <tt><ref id=".A8" name=".A8"></tt>,
3325 <tt><ref id=".I16" name=".I16"></tt>,
3326 <tt><ref id=".I8" name=".I8"></tt>
3329 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3331 Starts a struct definition. Structs are covered in a separate section named
3332 <ref id="structs" name=""Structs and unions"">.
3334 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3337 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3339 Enable the SunPlus instructions set. This command will not work in the
3340 freeware version of the assembler, because the instruction set is
3341 "proprietary and confidential".
3343 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3344 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3345 <tt><ref id=".P816" name=".P816"></tt>
3348 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3350 Allocate space for a struct or union.
3361 .tag Point ; Allocate 4 bytes
3365 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3367 Force an assembly warning. The assembler will output a warning message
3368 preceded by "User warning". This warning will always be output, even if
3369 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3370 command line option.
3372 This command may be used to output possible problems when assembling
3381 .warning "Forward jump in jne, cannot optimize!"
3391 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
3392 name=".OUT"></tt> directives.
3395 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3397 Define word sized data. Must be followed by a sequence of (word ranged,
3398 but not necessarily constant) expressions.
3403 .word $0D00, $AF13, _Clear
3407 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3409 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3410 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3414 .segment "ZEROPAGE", zeropage
3417 Because of the "zeropage" attribute, labels declared in this segment are
3418 addressed using direct addressing mode if possible. You <em/must/ instruct
3419 the linker to place this segment somewhere in the address range 0..$FF
3420 otherwise you will get errors.
3422 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3426 <sect>Macros<label id="macros"><p>
3429 <sect1>Introduction<p>
3431 Macros may be thought of as "parametrized super instructions". Macros are
3432 sequences of tokens that have a name. If that name is used in the source
3433 file, the macro is "expanded", that is, it is replaced by the tokens that
3434 were specified when the macro was defined.
3437 <sect1>Macros without parameters<p>
3439 In it's simplest form, a macro does not have parameters. Here's an
3443 .macro asr ; Arithmetic shift right
3444 cmp #$80 ; Put bit 7 into carry
3445 ror ; Rotate right with carry
3449 The macro above consists of two real instructions, that are inserted into
3450 the code, whenever the macro is expanded. Macro expansion is simply done
3451 by using the name, like this:
3460 <sect1>Parametrized macros<p>
3462 When using macro parameters, macros can be even more useful:
3476 When calling the macro, you may give a parameter, and each occurrence of
3477 the name "addr" in the macro definition will be replaced by the given
3496 A macro may have more than one parameter, in this case, the parameters
3497 are separated by commas. You are free to give less parameters than the
3498 macro actually takes in the definition. You may also leave intermediate
3499 parameters empty. Empty parameters are replaced by empty space (that is,
3500 they are removed when the macro is expanded). If you have a look at our
3501 macro definition above, you will see, that replacing the "addr" parameter
3502 by nothing will lead to wrong code in most lines. To help you, writing
3503 macros with a variable parameter list, there are some control commands:
3505 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3506 returns true, if there are any tokens on the remainder of the line. Since
3507 empty parameters are replaced by nothing, this may be used to test if a given
3508 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3511 Look at this example:
3514 .macro ldaxy a, x, y
3527 This macro may be called as follows:
3530 ldaxy 1, 2, 3 ; Load all three registers
3532 ldaxy 1, , 3 ; Load only a and y
3534 ldaxy , , 3 ; Load y only
3537 There's another helper command for determining, which macro parameters are
3538 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3539 replaced by the parameter count given, <em/including/ intermediate empty macro
3543 ldaxy 1 ; .PARAMCOUNT = 1
3544 ldaxy 1,,3 ; .PARAMCOUNT = 3
3545 ldaxy 1,2 ; .PARAMCOUNT = 2
3546 ldaxy 1, ; .PARAMCOUNT = 2
3547 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3550 Macro parameters may optionally be enclosed into curly braces. This allows the
3551 inclusion of tokens that would otherwise terminate the parameter (the comma in
3552 case of a macro parameter).
3555 .macro foo arg1, arg2
3559 foo ($00,x) ; Two parameters passed
3560 foo {($00,x)} ; One parameter passed
3563 In the first case, the macro is called with two parameters: '<tt/($00/'
3564 and 'x)'. The comma is not passed to the macro, since it is part of the
3565 calling sequence, not the parameters.
3567 In the second case, '($00,x)' is passed to the macro, this time
3568 including the comma.
3571 <sect1>Detecting parameter types<p>
3573 Sometimes it is nice to write a macro that acts differently depending on the
3574 type of the argument supplied. An example would be a macro that loads a 16 bit
3575 value from either an immediate operand, or from memory. The <tt/<ref
3576 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3577 functions will allow you to do exactly this:
3581 .if (.match (.left (1, {arg}), #))
3583 lda #<(.right (.tcount ({arg})-1, {arg}))
3584 ldx #>(.right (.tcount ({arg})-1, {arg}))
3586 ; assume absolute or zero page
3593 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3594 check if its argument begins with a hash mark. If so, two immediate loads are
3595 emitted, Otherwise a load from an absolute zero page memory location is
3596 assumed. Please note how the curly braces are used to enclose parameters to
3597 pseudo functions handling token lists. This is necessary, because the token
3598 lists may include commas or parens, which would be treated by the assembler
3601 The macro can be used as
3606 ldax #$1234 ; X=$12, A=$34
3608 ldax foo ; X=$56, A=$78
3612 <sect1>Recursive macros<p>
3614 Macros may be used recursively:
3617 .macro push r1, r2, r3
3626 There's also a special macro to help writing recursive macros: <tt><ref
3627 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3631 .macro push r1, r2, r3, r4, r5, r6, r7
3633 ; First parameter is empty
3639 push r2, r3, r4, r5, r6, r7
3643 When expanding this macro, the expansion will push all given parameters
3644 until an empty one is encountered. The macro may be called like this:
3647 push $20, $21, $32 ; Push 3 ZP locations
3648 push $21 ; Push one ZP location
3652 <sect1>Local symbols inside macros<p>
3654 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3655 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3656 Have a look at the inc16 macro above. Here is it again:
3670 If you have a closer look at the code, you will notice, that it could be
3671 written more efficiently, like this:
3682 But imagine what happens, if you use this macro twice? Since the label
3683 "Skip" has the same name both times, you get a "duplicate symbol" error.
3684 Without a way to circumvent this problem, macros are not as useful, as
3685 they could be. One solution is, to start a new lexical block inside the
3699 Now the label is local to the block and not visible outside. However,
3700 sometimes you want a label inside the macro to be visible outside. To make
3701 that possible, there's a new command that's only usable inside a macro
3702 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3703 or more symbols as local to the macro expansion. The names of local variables
3704 are replaced by a unique name in each separate macro expansion. So we could
3705 also solve the problem above by using <tt/.LOCAL/:
3709 .local Skip ; Make Skip a local symbol
3716 Skip: ; Not visible outside
3721 <sect1>C style macros<p>
3723 Starting with version 2.5 of the assembler, there is a second macro type
3724 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3725 similar to the classic macro type described above, but behaviour is sometimes
3730 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3731 span more than a line. You may use line continuation (see <tt><ref
3732 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3733 more than one line for increased readability, but the macro itself
3734 may not contain an end-of-line token.
3736 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3737 the name space with classic macros, but they are detected and replaced
3738 at the scanner level. While classic macros may be used in every place,
3739 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3740 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3741 they are more versatile in some situations.
3743 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3744 parameters. While classic macros may have empty parameters, this is
3745 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3746 For this macro type, the number of actual parameters must match
3747 exactly the number of formal parameters.
3749 To make this possible, formal parameters are enclosed in braces when
3750 defining the macro. If there are no parameters, the empty braces may
3753 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3754 contain end-of-line tokens, there are things that cannot be done. They
3755 may not contain several processor instructions for example. So, while
3756 some things may be done with both macro types, each type has special
3757 usages. The types complement each other.
3761 Let's look at a few examples to make the advantages and disadvantages
3764 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3765 following <tt/.DEFINE/:
3770 foo EQU $1234 ; This is accepted now
3773 You may use the directive to define string constants used elsewhere:
3776 ; Define the version number
3777 .define VERSION "12.3a"
3783 Macros with parameters may also be useful:
3786 .define DEBUG(message) .out message
3788 DEBUG "Assembling include file #3"
3791 Note that, while formal parameters have to be placed in braces, this is
3792 not true for the actual parameters. Beware: Since the assembler cannot
3793 detect the end of one parameter, only the first token is used. If you
3794 don't like that, use classic macros instead:
3802 (This is an example where a problem can be solved with both macro types).
3805 <sect1>Characters in macros<p>
3807 When using the <ref id="option-t" name="-t"> option, characters are translated
3808 into the target character set of the specific machine. However, this happens
3809 as late as possible. This means that strings are translated if they are part
3810 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3811 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3812 used as part of an expression.
3814 This behaviour is very intuitive outside of macros but may be confusing when
3815 doing more complex macros. If you compare characters against numeric values,
3816 be sure to take the translation into account.
3821 <sect>Macro packages<label id="macropackages"><p>
3823 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3824 macro packages may be included with just one command. Available macro packages
3828 <sect1><tt>.MACPACK generic</tt><p>
3830 This macro package defines macros that are useful in almost any program.
3831 Currently, two macros are defined:
3846 <sect1><tt>.MACPACK longbranch</tt><p>
3848 This macro package defines long conditional jumps. They are named like the
3849 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3850 definition for the "<tt/jeq/" macro, the other macros are built using the same
3855 .if .def(Target) .and ((*+2)-(Target) <= 127)
3864 All macros expand to a short branch, if the label is already defined (back
3865 jump) and is reachable with a short jump. Otherwise the macro expands to a
3866 conditional branch with the branch condition inverted, followed by an absolute
3867 jump to the actual branch target.
3869 The package defines the following macros:
3872 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3877 <sect1><tt>.MACPACK cbm</tt><p>
3879 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3880 string as argument and places this string into memory translated into screen
3884 <sect1><tt>.MACPACK cpu</tt><p>
3886 This macro package does not define any macros but constants used to examine
3887 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3888 each supported CPU a constant similar to
3900 is defined. These constants may be used to determine the exact type of the
3901 currently enabled CPU. In addition to that, for each CPU instruction set,
3902 another constant is defined:
3914 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3915 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3916 currently enabled CPU supports a specific instruction set. For example the
3917 65C02 supports all instructions of the 65SC02 CPU, so it has the
3918 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3922 .if (.cpu .bitand CPU_ISET_65SC02)
3930 it is possible to determine if the
3936 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3937 CPUs (the latter two are upwards compatible to the 65SC02).
3941 <sect>Predefined constants<label id="predefined-constants"><p>
3943 For better orthogonality, the assembler defines similar symbols as the
3944 compiler, depending on the target system selected:
3947 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
3948 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
3949 <item><tt/__ATARI__/ - Target system is <tt/atari/
3950 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
3951 <item><tt/__BBC__/ - Target system is <tt/bbc/
3952 <item><tt/__C128__/ - Target system is <tt/c128/
3953 <item><tt/__C16__/ - Target system is <tt/c16/
3954 <item><tt/__C64__/ - Target system is <tt/c64/
3955 <item><tt/__CBM__/ - Target is a Commodore system
3956 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
3957 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
3958 <item><tt/__GEOS__/ - Target system is <tt/geos/
3959 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
3960 <item><tt/__NES__/ - Target system is <tt/nes/
3961 <item><tt/__PET__/ - Target system is <tt/pet/
3962 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
3963 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
3964 <item><tt/__VIC20__/ - Target system is <tt/vic20/
3968 <sect>Structs and unions<label id="structs"><p>
3970 <sect1>Structs and unions Overview<p>
3972 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3973 are to some degree comparable to their C counterparts. Both have a list of
3974 members. Each member allocates storage and may optionally have a name, which,
3975 in case of a struct, is the offset from the beginning and, in case of a union,
3979 <sect1>Declaration<p>
3981 Here is an example for a very simple struct with two members and a total size
3991 A union shares the total space between all its members, its size is the same
3992 as that of the largest member.
3994 A struct or union must not necessarily have a name. If it is anonymous, no
3995 local scope is opened, the identifiers used to name the members are placed
3996 into the current scope instead.
3998 A struct may contain unnamed members and definitions of local structs. The
3999 storage allocators may contain a multiplier, as in the example below:
4004 .word 2 ; Allocate two words
4011 <sect1>The <tt/.TAG/ keyword<p>
4013 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4014 for an already defined struct or unions within another struct:
4028 Space for a struct or union may be allocated using the <ref id=".TAG"
4029 name=".TAG"> directive.
4035 Currently, members are just offsets from the start of the struct or union. To
4036 access a field of a struct, the member offset has to be added to the address
4037 of the struct itself:
4040 lda C+Circle::Radius ; Load circle radius into A
4043 This may change in a future version of the assembler.
4046 <sect1>Limitations<p>
4048 Structs and unions are currently implemented as nested symbol tables (in fact,
4049 they were a by-product of the improved scoping rules). Currently, the
4050 assembler has no idea of types. This means that the <ref id=".TAG"
4051 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4052 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4053 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4054 this structure accessible by using the '::' operator.
4058 <sect>Module constructors/destructors<label id="condes"><p>
4060 <em>Note:</em> This section applies mostly to C programs, so the explanation
4061 below uses examples from the C libraries. However, the feature may also be
4062 useful for assembler programs.
4065 <sect1>Module constructors/destructors Overview<p>
4067 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4068 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4069 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
4070 special way. The linker is able to generate tables with all functions of a
4071 specific type. Such a table will <em>only</em> include symbols from object
4072 files that are linked into a specific executable. This may be used to add
4073 initialization and cleanup code for library modules, or a table of interrupt
4076 The C heap functions are an example where module initialization code is used.
4077 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4078 variables that contain the start and the end of the heap, pointers to the free
4079 list and so on. Since the end of the heap depends on the size and start of the
4080 stack, it must be initialized at runtime. However, initializing these
4081 variables for programs that do not use the heap are a waste of time and
4084 So the central module defines a function that contains initialization code and
4085 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4086 this module is added to an executable by the linker, the initialization
4087 function will be placed into the table of constructors by the linker. The C
4088 startup code will call all constructors before <tt/main/ and all destructors
4089 after <tt/main/, so without any further work, the heap initialization code is
4090 called once the module is linked in.
4092 While it would be possible to add explicit calls to initialization functions
4093 in the startup code, the new approach has several advantages:
4097 If a module is not included, the initialization code is not linked in and not
4098 called. So you don't pay for things you don't need.
4101 Adding another library that needs initialization does not mean that the
4102 startup code has to be changed. Before we had module constructors and
4103 destructors, the startup code for all systems had to be adjusted to call the
4104 new initialization code.
4107 The feature saves memory: Each additional initialization function needs just
4108 two bytes in the table (a pointer to the function).
4113 <sect1>Calling order<p>
4115 The symbols are sorted in increasing priority order by the linker when using
4116 one of the builtin linker configurations, so the functions with lower
4117 priorities come first and are followed by those with higher priorities. The C
4118 library runtime subroutine that walks over the function tables calls the
4119 functions starting from the top of the table - which means that functions with
4120 a high priority are called first.
4122 So when using the C runtime, functions are called with high priority functions
4123 first, followed by low priority functions.
4128 When using these special symbols, please take care of the following:
4133 The linker will only generate function tables, it will not generate code to
4134 call these functions. If you're using the feature in some other than the
4135 existing C environments, you have to write code to call all functions in a
4136 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4137 in the C runtime for an example on how to do this.
4140 The linker will only add addresses of functions that are in modules linked to
4141 the executable. This means that you have to be careful where to place the
4142 condes functions. If initialization or an irq handler is needed for a group of
4143 functions, be sure to place the function into a module that is linked in
4144 regardless of which function is called by the user.
4147 The linker will generate the tables only when requested to do so by the
4148 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4149 be requested separately.
4152 Constructors and destructors may have priorities. These priorities determine
4153 the order of the functions in the table. If your initialization or cleanup code
4154 does depend on other initialization or cleanup code, you have to choose the
4155 priority for the functions accordingly.
4158 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4159 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4160 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4161 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4162 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4163 (interruptor). The linker generates a separate table for each type on request.
4168 <sect>Porting sources from other assemblers<p>
4170 Sometimes it is necessary to port code written for older assemblers to ca65.
4171 In some cases, this can be done without any changes to the source code by
4172 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4173 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4176 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4177 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4178 done by the linker. Most other assemblers generate absolute code, placement is
4179 done within the assembler and there is no external linker.
4181 In general it is not a good idea to write new code using the emulation
4182 features of the assembler, but there may be situations where even this rule is
4187 You need to use some of the ca65 emulation features to simulate the behaviour
4188 of such simple assemblers.
4191 <item>Prepare your sourcecode like this:
4194 ; if you want TASS style labels without colons
4195 .feature labels_without_colons
4197 ; if you want TASS style character constants
4198 ; ("a" instead of the default 'a')
4199 .feature loose_char_term
4201 .word *+2 ; the cbm load address
4206 notice that the two emulation features are mostly useful for porting
4207 sources originally written in/for TASS, they are not needed for the
4208 actual "simple assembler operation" and are not recommended if you are
4209 writing new code from scratch.
4211 <item>Replace all program counter assignments (which are not possible in ca65
4212 by default, and the respective emulation feature works different from what
4213 you'd expect) by another way to skip to memory locations, for example the
4214 <tt><ref id=".RES" name=".RES"></tt> directive.
4218 .res $2000-* ; reserve memory up to $2000
4221 Please note that other than the original TASS, ca65 can never move the program
4222 counter backwards - think of it as if you are assembling to disk with TASS.
4224 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4225 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4226 of <tt/.goto/, everything involving loops must be replaced by
4227 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4229 <item>To assemble code to a different address than it is executed at, use the
4230 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4231 <tt/.offs/-constructs.
4238 .reloc ; back to normal
4241 <item>Then assemble like this:
4244 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4247 Note that you need to use the actual start address minus two, since two bytes
4248 are used for the cbm load address.
4253 <sect>Bugs/Feedback<p>
4255 If you have problems using the assembler, if you find any bugs, or if
4256 you're doing something interesting with the assembler, I would be glad to
4257 hear from you. Feel free to contact me by email
4258 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4264 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4265 Bassewitz. For usage of the binaries and/or sources the following
4266 conditions do apply:
4268 This software is provided 'as-is', without any expressed or implied
4269 warranty. In no event will the authors be held liable for any damages
4270 arising from the use of this software.
4272 Permission is granted to anyone to use this software for any purpose,
4273 including commercial applications, and to alter it and redistribute it
4274 freely, subject to the following restrictions:
4277 <item> The origin of this software must not be misrepresented; you must not
4278 claim that you wrote the original software. If you use this software
4279 in a product, an acknowledgment in the product documentation would be
4280 appreciated but is not required.
4281 <item> Altered source versions must be plainly marked as such, and must not
4282 be misrepresented as being the original software.
4283 <item> This notice may not be removed or altered from any source