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/ or <tt/error/. The assertion is
1754 evaluated by the assembler if possible, and also passed to the linker in the
1755 object file (if one is generated). The linker will then evaluate the
1756 expression when segment placement has been done.
1761 .assert * = $8000, error, "Code not at $8000"
1764 The example assertion will check that the current location is at $8000,
1765 when the output file is written, and abort with an error if this is not
1766 the case. More complex expressions are possible. The action specifier
1767 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1768 an error message. In the latter case, generation of the output file is
1769 suppressed in both the assembler and linker.
1772 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1774 Is followed by a plus or a minus character. When switched on (using a
1775 +), undefined symbols are automatically marked as import instead of
1776 giving errors. When switched off (which is the default so this does not
1777 make much sense), this does not happen and an error message is
1778 displayed. The state of the autoimport flag is evaluated when the
1779 complete source was translated, before outputting actual code, so it is
1780 <em/not/ possible to switch this feature on or off for separate sections
1781 of code. The last setting is used for all symbols.
1783 You should probably not use this switch because it delays error
1784 messages about undefined symbols until the link stage. The cc65
1785 compiler (which is supposed to produce correct assembler code in all
1786 circumstances, something which is not true for most assembler
1787 programmers) will insert this command to avoid importing each and every
1788 routine from the runtime library.
1793 .autoimport + ; Switch on auto import
1796 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
1798 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
1799 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
1800 the operator '^' prepended to each expression in its list.
1805 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
1807 TableLookupLo: .lobytes MyTable
1808 TableLookupHi: .hibytes MyTable
1809 TableLookupBank: .bankbytes MyTable
1812 which is equivalent to
1815 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
1816 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
1817 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
1820 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
1821 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
1822 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
1825 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1827 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1828 so this is a shortcut for
1834 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1837 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1839 Define byte sized data. Must be followed by a sequence of (byte ranged)
1840 expressions or strings.
1846 .byt "world", $0D, $00
1850 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1852 Switch on or off case sensitivity on identifiers. The default is off
1853 (that is, identifiers are case sensitive), but may be changed by the
1854 -i switch on the command line.
1855 The command must be followed by a '+' or '-' character to switch the
1856 option on or off respectively.
1861 .case - ; Identifiers are not case sensitive
1865 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1867 Apply a custom mapping for characters. The command is followed by two
1868 numbers in the range 1..255. The first one is the index of the source
1869 character, the second one is the mapping. The mapping applies to all
1870 character and string constants when they generate output, and overrides
1871 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1872 command line switch.
1877 .charmap $41, $61 ; Map 'A' to 'a'
1881 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1883 Switch to the CODE segment. The name of the CODE segment is always
1884 "CODE", so this is a shortcut for
1890 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1893 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1895 Export a symbol and mark it in a special way. The linker is able to build
1896 tables of all such symbols. This may be used to automatically create a list
1897 of functions needed to initialize linked library modules.
1899 Note: The linker has a feature to build a table of marked routines, but it
1900 is your code that must call these routines, so just declaring a symbol with
1901 <tt/.CONDES/ does nothing by itself.
1903 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1904 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1905 is implied by <tt/.CONDES/.
1907 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1908 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1909 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1910 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1911 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1912 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
1913 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
1915 After the type, an optional priority may be specified. Higher numeric values
1916 mean higher priority. If no priority is given, the default priority of 7 is
1917 used. Be careful when assigning priorities to your own module constructors
1918 so they won't interfere with the ones in the cc65 library.
1923 .condes ModuleInit, constructor
1924 .condes ModInit, 0, 16
1927 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1928 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1929 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
1930 name="Module constructors/destructors"> explaining the feature in more
1934 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1936 Export a symbol and mark it as a module constructor. This may be used
1937 together with the linker to build a table of constructor subroutines that
1938 are called by the startup code.
1940 Note: The linker has a feature to build a table of marked routines, but it
1941 is your code that must call these routines, so just declaring a symbol as
1942 constructor does nothing by itself.
1944 A constructor is always exported as an absolute (16 bit) symbol. You don't
1945 need to use an additional <tt/.export/ statement, this is implied by
1946 <tt/.constructor/. It may have an optional priority that is separated by a
1947 comma. Higher numeric values mean a higher priority. If no priority is
1948 given, the default priority of 7 is used. Be careful when assigning
1949 priorities to your own module constructors so they won't interfere with the
1950 ones in the cc65 library.
1955 .constructor ModuleInit
1956 .constructor ModInit, 16
1959 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1960 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1961 <ref id="condes" name="Module constructors/destructors"> explaining the
1962 feature in more detail.
1965 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1967 Switch to the DATA segment. The name of the DATA segment is always
1968 "DATA", so this is a shortcut for
1974 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1977 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1979 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1980 create word sized data in native 65XX format). Must be followed by a
1981 sequence of (word ranged) expressions.
1989 This will emit the bytes
1995 into the current segment in that order.
1998 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2000 Switch on or off debug info generation. The default is off (that is,
2001 the object file will not contain debug infos), but may be changed by the
2002 -g switch on the command line.
2003 The command must be followed by a '+' or '-' character to switch the
2004 option on or off respectively.
2009 .debuginfo + ; Generate debug info
2013 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2015 Start a define style macro definition. The command is followed by an
2016 identifier (the macro name) and optionally by a list of formal arguments
2018 See section <ref id="macros" name="Macros">.
2021 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2023 Builtin function. The function expects an identifier as argument in braces.
2024 The argument is evaluated, and the function yields "true" if the identifier
2025 is a symbol that is already defined somewhere in the source file up to the
2026 current position. Otherwise the function yields false. As an example, the
2027 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2034 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2036 Export a symbol and mark it as a module destructor. This may be used
2037 together with the linker to build a table of destructor subroutines that
2038 are called by the startup code.
2040 Note: The linker has a feature to build a table of marked routines, but it
2041 is your code that must call these routines, so just declaring a symbol as
2042 constructor does nothing by itself.
2044 A destructor is always exported as an absolute (16 bit) symbol. You don't
2045 need to use an additional <tt/.export/ statement, this is implied by
2046 <tt/.destructor/. It may have an optional priority that is separated by a
2047 comma. Higher numerical values mean a higher priority. If no priority is
2048 given, the default priority of 7 is used. Be careful when assigning
2049 priorities to your own module destructors so they won't interfere with the
2050 ones in the cc65 library.
2055 .destructor ModuleDone
2056 .destructor ModDone, 16
2059 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2060 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2061 section <ref id="condes" name="Module constructors/destructors"> explaining
2062 the feature in more detail.
2065 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2067 Define dword sized data (4 bytes) Must be followed by a sequence of
2073 .dword $12344512, $12FA489
2077 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2079 Conditional assembly: Reverse the current condition.
2082 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2084 Conditional assembly: Reverse current condition and test a new one.
2087 <sect1><tt>.END</tt><label id=".END"><p>
2089 Forced end of assembly. Assembly stops at this point, even if the command
2090 is read from an include file.
2093 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2095 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2098 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2100 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2101 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2104 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2106 End of macro definition (see section <ref id="macros" name="Macros">).
2109 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2111 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2114 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2116 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2119 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2121 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2124 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2126 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2127 command and the separate section named <ref id="structs" name=""Structs
2131 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2133 Start an enumeration. This directive is very similar to the C <tt/enum/
2134 keyword. If a name is given, a new scope is created for the enumeration,
2135 otherwise the enumeration members are placed in the enclosing scope.
2137 In the enumeration body, symbols are declared. The first symbol has a value
2138 of zero, and each following symbol will get the value of the preceding plus
2139 one. This behaviour may be overridden by an explicit assignment. Two symbols
2140 may have the same value.
2152 Above example will create a new scope named <tt/errorcodes/ with three
2153 symbols in it that get the values 0, 1 and 2 respectively. Another way
2154 to write this would have been:
2164 Please note that explicit scoping must be used to access the identifiers:
2167 .word errorcodes::no_error
2170 A more complex example:
2179 EWOULDBLOCK = EAGAIN
2183 In this example, the enumeration does not have a name, which means that the
2184 members will be visible in the enclosing scope and can be used in this scope
2185 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2186 The value for the following members is incremented by one, so <tt/EOK/ would
2187 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2188 override for the value using an already defined symbol.
2191 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2193 Force an assembly error. The assembler will output an error message
2194 preceded by "User error" and will <em/not/ produce an object file.
2196 This command may be used to check for initial conditions that must be
2197 set before assembling a source file.
2207 .error "Must define foo or bar!"
2211 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2212 id=".OUT" name=".OUT"></tt> directives.
2215 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2217 Abort a macro expansion immediately. This command is often useful in
2218 recursive macros. See separate section <ref id="macros" name="Macros">.
2221 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2223 Make symbols accessible from other modules. Must be followed by a comma
2224 separated list of symbols to export, with each one optionally followed by an
2225 address specification and (also optional) an assignment. Using an additional
2226 assignment in the export statement allows to define and export a symbol in
2227 one statement. The default is to export the symbol with the address size it
2228 actually has. The assembler will issue a warning, if the symbol is exported
2229 with an address size smaller than the actual address size.
2236 .export foobar: far = foo * bar
2237 .export baz := foobar, zap: far = baz - bar
2240 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2243 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2246 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2248 Make symbols accessible from other modules. Must be followed by a comma
2249 separated list of symbols to export. The exported symbols are explicitly
2250 marked as zero page symbols. An assignment may be included in the
2251 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2258 .exportzp baz := $02
2261 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2264 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2266 Define far (24 bit) address data. The command must be followed by a
2267 sequence of (not necessarily constant) expressions.
2272 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2275 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2278 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2280 This directive may be used to enable one or more compatibility features
2281 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2282 possible, it may be useful when porting sources written for other
2283 assemblers. There is no way to switch a feature off, once you have
2284 enabled it, so using
2290 will enable the feature until end of assembly is reached.
2292 The following features are available:
2296 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2298 Accept the at character (`@') as a valid character in identifiers. The
2299 at character is not allowed to start an identifier, even with this
2302 <tag><tt>c_comments</tt></tag>
2304 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2305 comment terminators. Note that C comments may not be nested. There's also a
2306 pitfall when using C like comments: All statements must be terminated by
2307 "end-of-line". Using C like comments, it is possible to hide the newline,
2308 which results in error messages. See the following non working example:
2311 lda #$00 /* This comment hides the newline
2315 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2317 Accept the dollar sign (`$') as a valid character in identifiers. The
2318 dollar character is not allowed to start an identifier, even with this
2321 <tag><tt>dollar_is_pc</tt></tag>
2323 The dollar sign may be used as an alias for the star (`*'), which
2324 gives the value of the current PC in expressions.
2325 Note: Assignment to the pseudo variable is not allowed.
2327 <tag><tt>labels_without_colons</tt></tag>
2329 Allow labels without a trailing colon. These labels are only accepted,
2330 if they start at the beginning of a line (no leading white space).
2332 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2334 Accept the dot (`.') as the first character of an identifier. This may be
2335 used for example to create macro names that start with a dot emulating
2336 control directives of other assemblers. Note however, that none of the
2337 reserved keywords built into the assembler, that starts with a dot, may be
2338 overridden. When using this feature, you may also get into trouble if
2339 later versions of the assembler define new keywords starting with a dot.
2341 <tag><tt>loose_char_term</tt></tag>
2343 Accept single quotes as well as double quotes as terminators for char
2346 <tag><tt>loose_string_term</tt></tag>
2348 Accept single quotes as well as double quotes as terminators for string
2351 <tag><tt>missing_char_term</tt></tag>
2353 Accept single quoted character constants where the terminating quote is
2358 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2359 loose_string_term/, since in this case the input would be ambiguous.
2361 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2363 This feature makes relocatable/absolute mode local to the current segment.
2364 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2365 effect will only enable absolute mode for the current segment. Dito for
2366 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2368 <tag><tt>pc_assignment</tt></tag>
2370 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2371 is enabled). Such an assignment is handled identical to the <tt><ref
2372 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2373 removing the lines with the assignments may also be an option when porting
2374 code written for older assemblers).
2376 <tag><tt>ubiquitous_idents</tt></tag>
2378 Allow the use of instructions names as names for macros and symbols. This
2379 makes it possible to "overload" instructions by defining a macro with the
2380 same name. This does also make it possible to introduce hard to find errors
2381 in your code, so be careful!
2385 It is also possible to specify features on the command line using the
2386 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2387 This is useful when translating sources written for older assemblers, when
2388 you don't want to change the source code.
2390 As an example, to translate sources written for Andre Fachats xa65
2391 assembler, the features
2394 labels_without_colons, pc_assignment, loose_char_term
2397 may be helpful. They do not make ca65 completely compatible, so you may not
2398 be able to translate the sources without changes, even when enabling these
2399 features. However, I have found several sources that translate without
2400 problems when enabling these features on the command line.
2403 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2405 Insert an option string into the object file. There are two forms of
2406 this command, one specifies the option by a keyword, the second
2407 specifies it as a number. Since usage of the second one needs knowledge
2408 of the internal encoding, its use is not recommended and I will only
2409 describe the first form here.
2411 The command is followed by one of the keywords
2419 a comma and a string. The option is written into the object file
2420 together with the string value. This is currently unidirectional and
2421 there is no way to actually use these options once they are in the
2427 .fileopt comment, "Code stolen from my brother"
2428 .fileopt compiler, "BASIC 2.0"
2429 .fopt author, "J. R. User"
2433 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2435 Import an absolute symbol from another module. The command is followed by a
2436 comma separated list of symbols to import. The command is similar to <tt>
2437 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2438 written to the generated object file, even if the symbol is never referenced
2439 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2440 references for unused symbols).
2445 .forceimport needthisone, needthistoo
2448 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2451 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2453 Declare symbols as global. Must be followed by a comma separated list of
2454 symbols to declare. Symbols from the list, that are defined somewhere in the
2455 source, are exported, all others are imported. Additional <tt><ref
2456 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2457 name=".EXPORT"></tt> commands for the same symbol are allowed.
2466 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2468 Declare symbols as global. Must be followed by a comma separated list of
2469 symbols to declare. Symbols from the list, that are defined somewhere in the
2470 source, are exported, all others are imported. Additional <tt><ref
2471 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2472 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2473 in the list are explicitly marked as zero page symbols.
2481 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2483 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2484 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2485 the operator '>' prepended to each expression in its list.
2490 .lobytes $1234, $2345, $3456, $4567
2491 .hibytes $fedc, $edcb, $dcba, $cba9
2494 which is equivalent to
2497 .byte $34, $45, $56, $67
2498 .byte $fe, $ed, $dc, $cb
2504 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2506 TableLookupLo: .lobytes MyTable
2507 TableLookupHi: .hibytes MyTable
2510 which is equivalent to
2513 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2514 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2517 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2518 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2519 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2522 <sect1><tt>.I16</tt><label id=".I16"><p>
2524 Valid only in 65816 mode. Switch the index registers to 16 bit.
2526 Note: This command will not emit any code, it will tell the assembler to
2527 create 16 bit operands for immediate operands.
2529 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2530 name=".SMART"></tt> commands.
2533 <sect1><tt>.I8</tt><label id=".I8"><p>
2535 Valid only in 65816 mode. Switch the index registers to 8 bit.
2537 Note: This command will not emit any code, it will tell the assembler to
2538 create 8 bit operands for immediate operands.
2540 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2541 name=".SMART"></tt> commands.
2544 <sect1><tt>.IF</tt><label id=".IF"><p>
2546 Conditional assembly: Evaluate an expression and switch assembler output
2547 on or off depending on the expression. The expression must be a constant
2548 expression, that is, all operands must be defined.
2550 A expression value of zero evaluates to FALSE, any other value evaluates
2554 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2556 Conditional assembly: Check if there are any remaining tokens in this line,
2557 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2558 condition is not true, further lines are not assembled until an <tt><ref
2559 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2560 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2562 This command is often used to check if a macro parameter was given. Since an
2563 empty macro parameter will evaluate to nothing, the condition will evaluate
2564 to FALSE if an empty parameter was given.
2578 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2581 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2583 Conditional assembly: Evaluate an expression and switch assembler output
2584 on or off depending on the constness of the expression.
2586 A const expression evaluates to to TRUE, a non const expression (one
2587 containing an imported or currently undefined symbol) evaluates to
2590 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2593 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2595 Conditional assembly: Check if a symbol is defined. Must be followed by
2596 a symbol name. The condition is true if the the given symbol is already
2597 defined, and false otherwise.
2599 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2602 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2604 Conditional assembly: Check if there are any remaining tokens in this line,
2605 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2606 condition is not true, further lines are not assembled until an <tt><ref
2607 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2608 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2610 This command is often used to check if a macro parameter was given.
2611 Since an empty macro parameter will evaluate to nothing, the condition
2612 will evaluate to FALSE if an empty parameter was given.
2625 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2628 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2630 Conditional assembly: Check if a symbol is defined. Must be followed by
2631 a symbol name. The condition is true if the the given symbol is not
2632 defined, and false otherwise.
2634 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2637 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2639 Conditional assembly: Check if a symbol is referenced. Must be followed
2640 by a symbol name. The condition is true if if the the given symbol was
2641 not referenced before, and false otherwise.
2643 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2646 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2648 Conditional assembly: Check if the assembler is currently in 6502 mode
2649 (see <tt><ref id=".P02" name=".P02"></tt> command).
2652 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2654 Conditional assembly: Check if the assembler is currently in 65816 mode
2655 (see <tt><ref id=".P816" name=".P816"></tt> command).
2658 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2660 Conditional assembly: Check if the assembler is currently in 65C02 mode
2661 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2664 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2666 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2667 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2670 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2672 Conditional assembly: Check if a symbol is referenced. Must be followed
2673 by a symbol name. The condition is true if if the the given symbol was
2674 referenced before, and false otherwise.
2676 This command may be used to build subroutine libraries in include files
2677 (you may use separate object modules for this purpose too).
2682 .ifref ToHex ; If someone used this subroutine
2683 ToHex: tay ; Define subroutine
2689 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2692 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2694 Import a symbol from another module. The command is followed by a comma
2695 separated list of symbols to import, with each one optionally followed by
2696 an address specification.
2702 .import bar: zeropage
2705 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2708 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2710 Import a symbol from another module. The command is followed by a comma
2711 separated list of symbols to import. The symbols are explicitly imported
2712 as zero page symbols (that is, symbols with values in byte range).
2720 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2723 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2725 Include a file as binary data. The command expects a string argument
2726 that is the name of a file to include literally in the current segment.
2727 In addition to that, a start offset and a size value may be specified,
2728 separated by commas. If no size is specified, all of the file from the
2729 start offset to end-of-file is used. If no start position is specified
2730 either, zero is assumed (which means that the whole file is inserted).
2735 ; Include whole file
2736 .incbin "sprites.dat"
2738 ; Include file starting at offset 256
2739 .incbin "music.dat", $100
2741 ; Read 100 bytes starting at offset 200
2742 .incbin "graphics.dat", 200, 100
2746 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2748 Include another file. Include files may be nested up to a depth of 16.
2757 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
2759 Export a symbol and mark it as an interruptor. This may be used together
2760 with the linker to build a table of interruptor subroutines that are called
2763 Note: The linker has a feature to build a table of marked routines, but it
2764 is your code that must call these routines, so just declaring a symbol as
2765 interruptor does nothing by itself.
2767 An interruptor is always exported as an absolute (16 bit) symbol. You don't
2768 need to use an additional <tt/.export/ statement, this is implied by
2769 <tt/.interruptor/. It may have an optional priority that is separated by a
2770 comma. Higher numeric values mean a higher priority. If no priority is
2771 given, the default priority of 7 is used. Be careful when assigning
2772 priorities to your own module constructors so they won't interfere with the
2773 ones in the cc65 library.
2778 .interruptor IrqHandler
2779 .interruptor Handler, 16
2782 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
2783 section <ref id="condes" name="Module constructors/destructors"> explaining
2784 the feature in more detail.
2787 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2789 Switch on or off line continuations using the backslash character
2790 before a newline. The option is off by default.
2791 Note: Line continuations do not work in a comment. A backslash at the
2792 end of a comment is treated as part of the comment and does not trigger
2794 The command must be followed by a '+' or '-' character to switch the
2795 option on or off respectively.
2800 .linecont + ; Allow line continuations
2803 #$20 ; This is legal now
2807 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2809 Enable output to the listing. The command must be followed by a boolean
2810 switch ("on", "off", "+" or "-") and will enable or disable listing
2812 The option has no effect if the listing is not enabled by the command line
2813 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2814 to the listing file, if the counter is greater than zero, and suppressed if
2815 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2821 .list on ; Enable listing output
2825 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2827 Set, how many bytes are shown in the listing for one source line. The
2828 default is 12, so the listing will show only the first 12 bytes for any
2829 source line that generates more than 12 bytes of code or data.
2830 The directive needs an argument, which is either "unlimited", or an
2831 integer constant in the range 4..255.
2836 .listbytes unlimited ; List all bytes
2837 .listbytes 12 ; List the first 12 bytes
2838 .incbin "data.bin" ; Include large binary file
2842 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
2844 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
2845 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2846 the operator '<' prepended to each expression in its list.
2851 .lobytes $1234, $2345, $3456, $4567
2852 .hibytes $fedc, $edcb, $dcba, $cba9
2855 which is equivalent to
2858 .byte $34, $45, $56, $67
2859 .byte $fe, $ed, $dc, $cb
2865 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2867 TableLookupLo: .lobytes MyTable
2868 TableLookupHi: .hibytes MyTable
2871 which is equivalent to
2874 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2875 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2878 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2879 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2880 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2883 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2885 This command may only be used inside a macro definition. It declares a
2886 list of identifiers as local to the macro expansion.
2888 A problem when using macros are labels: Since they don't change their name,
2889 you get a "duplicate symbol" error if the macro is expanded the second time.
2890 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2891 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2894 Some other assemblers start a new lexical block inside a macro expansion.
2895 This has some drawbacks however, since that will not allow <em/any/ symbol
2896 to be visible outside a macro, a feature that is sometimes useful. The
2897 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2898 to address the problem.
2900 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2904 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2906 Defines the character that start "cheap" local labels. You may use one
2907 of '@' and '?' as start character. The default is '@'.
2909 Cheap local labels are labels that are visible only between two non
2910 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2911 using explicit lexical nesting.
2918 Clear: lda #$00 ; Global label
2919 ?Loop: sta Mem,y ; Local label
2923 Sub: ... ; New global label
2924 bne ?Loop ; ERROR: Unknown identifier!
2928 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2930 Insert a predefined macro package. The command is followed by an
2931 identifier specifying the macro package to insert. Available macro
2935 atari Defines the scrcode macro.
2936 cbm Defines the scrcode macro.
2937 cpu Defines constants for the .CPU variable.
2938 generic Defines generic macros like add and sub.
2939 longbranch Defines conditional long jump macros.
2942 Including a macro package twice, or including a macro package that
2943 redefines already existing macros will lead to an error.
2948 .macpack longbranch ; Include macro package
2950 cmp #$20 ; Set condition codes
2951 jne Label ; Jump long on condition
2954 Macro packages are explained in more detail in section <ref
2955 id="macropackages" name="Macro packages">.
2958 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2960 Start a classic macro definition. The command is followed by an identifier
2961 (the macro name) and optionally by a comma separated list of identifiers
2962 that are macro parameters.
2964 See section <ref id="macros" name="Macros">.
2967 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2969 Start a section of absolute code. The command is followed by a constant
2970 expression that gives the new PC counter location for which the code is
2971 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2974 By default, absolute/relocatable mode is global (valid even when switching
2975 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
2976 it can be made segment local.
2978 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
2979 code at a specific address is the job of the linker, not the assembler, so
2980 there is usually no reason to assemble code to a specific address.
2985 .org $7FF ; Emit code starting at $7FF
2989 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2991 Output a string to the console without producing an error. This command
2992 is similar to <tt/.ERROR/, however, it does not force an assembler error
2993 that prevents the creation of an object file.
2998 .out "This code was written by the codebuster(tm)"
3001 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
3002 id=".ERROR" name=".ERROR"></tt> directives.
3005 <sect1><tt>.P02</tt><label id=".P02"><p>
3007 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3008 instructions. This is the default if not overridden by the
3009 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3011 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3012 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3015 <sect1><tt>.P816</tt><label id=".P816"><p>
3017 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3018 6502 instruction sets.
3020 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3021 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3024 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3026 Set the page length for the listing. Must be followed by an integer
3027 constant. The value may be "unlimited", or in the range 32 to 127. The
3028 statement has no effect if no listing is generated. The default value is -1
3029 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3030 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3031 after assembly is complete, you cannot use multiple line lengths with one
3032 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3037 .pagelength 66 ; Use 66 lines per listing page
3039 .pagelength unlimited ; Unlimited page length
3043 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3045 Enable the 65C02 instructions set. This instruction set includes all
3046 6502 and 65SC02 instructions.
3048 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3049 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3052 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3054 Pop the last pushed segment from the stack, and set it.
3056 This command will switch back to the segment that was last pushed onto the
3057 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3058 command, and remove this entry from the stack.
3060 The assembler will print an error message if the segment stack is empty
3061 when this command is issued.
3063 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3066 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3068 Start a nested lexical level with the given name and adds a symbol with this
3069 name to the enclosing scope. All new symbols from now on are in the local
3070 lexical level and are accessible from outside only via <ref id="scopesyntax"
3071 name="explicit scope specification">. Symbols defined outside this local
3072 level may be accessed as long as their names are not used for new symbols
3073 inside the level. Symbols names in other lexical levels do not clash, so you
3074 may use the same names for identifiers. The lexical level ends when the
3075 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3076 may be nested up to a depth of 16 (this is an artificial limit to protect
3077 against errors in the source).
3079 Note: Macro names are always in the global level and in a separate name
3080 space. There is no special reason for this, it's just that I've never
3081 had any need for local macro definitions.
3086 .proc Clear ; Define Clear subroutine, start new level
3088 L1: sta Mem,y ; L1 is local and does not cause a
3089 ; duplicate symbol error if used in other
3092 bne L1 ; Reference local symbol
3094 .endproc ; Leave lexical level
3097 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3101 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3103 Enable the 65SC02 instructions set. This instruction set includes all
3106 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3107 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3110 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3112 Push the currently active segment onto a stack. The entries on the stack
3113 include the name of the segment and the segment type. The stack has a size
3116 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3117 to switch to another segment and to restore the old segment later, without
3118 even knowing the name and type of the current segment.
3120 The assembler will print an error message if the segment stack is already
3121 full, when this command is issued.
3123 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3126 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3128 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3129 name=".ORG"></tt> command.
3132 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3134 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3135 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3136 a constant expression that tells how many times the commands in the body
3137 should get repeated. Optionally, a comma and an identifier may be specified.
3138 If this identifier is found in the body of the repeat statement, it is
3139 replaced by the current repeat count (starting with zero for the first time
3140 the body is repeated).
3142 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3143 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3144 level will be used, not the one from the outer level.
3148 The following macro will emit a string that is "encrypted" in that all
3149 characters of the string are XORed by the value $55.
3153 .repeat .strlen(Arg), I
3154 .byte .strat(Arg, I) ^ $55
3159 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3162 <sect1><tt>.RES</tt><label id=".RES"><p>
3164 Reserve storage. The command is followed by one or two constant
3165 expressions. The first one is mandatory and defines, how many bytes of
3166 storage should be defined. The second, optional expression must by a
3167 constant byte value that will be used as value of the data. If there
3168 is no fill value given, the linker will use the value defined in the
3169 linker configuration file (default: zero).
3174 ; Reserve 12 bytes of memory with value $AA
3179 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3181 Switch to the RODATA segment. The name of the RODATA segment is always
3182 "RODATA", so this is a shortcut for
3188 The RODATA segment is a segment that is used by the compiler for
3189 readonly data like string constants.
3191 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3194 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3196 Start a nested lexical level with the given name. All new symbols from now
3197 on are in the local lexical level and are accessible from outside only via
3198 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3199 outside this local level may be accessed as long as their names are not used
3200 for new symbols inside the level. Symbols names in other lexical levels do
3201 not clash, so you may use the same names for identifiers. The lexical level
3202 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3203 read. Lexical levels may be nested up to a depth of 16 (this is an
3204 artificial limit to protect against errors in the source).
3206 Note: Macro names are always in the global level and in a separate name
3207 space. There is no special reason for this, it's just that I've never
3208 had any need for local macro definitions.
3213 .scope Error ; Start new scope named Error
3215 File = 1 ; File error
3216 Parse = 2 ; Parse error
3217 .endscope ; Close lexical level
3220 lda #Error::File ; Use symbol from scope Error
3223 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3227 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3229 Switch to another segment. Code and data is always emitted into a
3230 segment, that is, a named section of data. The default segment is
3231 "CODE". There may be up to 254 different segments per object file
3232 (and up to 65534 per executable). There are shortcut commands for
3233 the most common segments ("CODE", "DATA" and "BSS").
3235 The command is followed by a string containing the segment name (there are
3236 some constraints for the name - as a rule of thumb use only those segment
3237 names that would also be valid identifiers). There may also be an optional
3238 address size separated by a colon. See the section covering <tt/<ref
3239 id="address-sizes" name="address sizes">/ for more information.
3241 The default address size for a segment depends on the memory model specified
3242 on the command line. The default is "absolute", which means that you don't
3243 have to use an address size modifier in most cases.
3245 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3246 That is, the segment will reside somewhere in core memory outside the zero
3247 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3248 page and direct (short) addressing is possible for data in this segment.
3250 Beware: Only labels in a segment with the zeropage attribute are marked
3251 as reachable by short addressing. The `*' (PC counter) operator will
3252 work as in other segments and will create absolute variable values.
3254 Please note that a segment cannot have two different address sizes. A
3255 segment specified as zeropage cannot be declared as being absolute later.
3260 .segment "ROM2" ; Switch to ROM2 segment
3261 .segment "ZP2": zeropage ; New direct segment
3262 .segment "ZP2" ; Ok, will use last attribute
3263 .segment "ZP2": absolute ; Error, redecl mismatch
3266 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3267 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3268 id=".RODATA" name=".RODATA"></tt>
3271 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3273 Switch the CPU instruction set. The command is followed by a string that
3274 specifies the CPU. Possible values are those that can also be supplied to
3275 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3276 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3277 note that support for the sunplus CPU is not available in the freeware
3278 version, because the instruction set of the sunplus CPU is "proprietary
3281 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3282 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3283 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3284 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3285 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3286 <tt><ref id=".P02" name=".P02"></tt>,
3287 <tt><ref id=".P816" name=".P816"></tt>,
3288 <tt><ref id=".PC02" name=".PC02"></tt>,
3289 <tt><ref id=".PSC02" name=".PSC02"></tt>
3292 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3294 Switch on or off smart mode. The command must be followed by a '+' or '-'
3295 character to switch the option on or off respectively. The default is off
3296 (that is, the assembler doesn't try to be smart), but this default may be
3297 changed by the -s switch on the command line.
3299 In smart mode the assembler will do the following:
3302 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3303 and update the operand sizes accordingly. If the operand of such an
3304 instruction cannot be evaluated by the assembler (for example, because
3305 the operand is an imported symbol), a warning is issued. Beware: Since
3306 the assembler cannot trace the execution flow this may lead to false
3307 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3308 instructions to tell the assembler about the current settings.
3309 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3310 used within a procedure declared as <tt/far/, or if the procedure has
3311 no explicit address specification, but it is <tt/far/ because of the
3319 .smart - ; Stop being smart
3322 See: <tt><ref id=".A16" name=".A16"></tt>,
3323 <tt><ref id=".A8" name=".A8"></tt>,
3324 <tt><ref id=".I16" name=".I16"></tt>,
3325 <tt><ref id=".I8" name=".I8"></tt>
3328 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3330 Starts a struct definition. Structs are covered in a separate section named
3331 <ref id="structs" name=""Structs and unions"">.
3333 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3336 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3338 Enable the SunPlus instructions set. This command will not work in the
3339 freeware version of the assembler, because the instruction set is
3340 "proprietary and confidential".
3342 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3343 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3344 <tt><ref id=".P816" name=".P816"></tt>
3347 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3349 Allocate space for a struct or union.
3360 .tag Point ; Allocate 4 bytes
3364 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3366 Force an assembly warning. The assembler will output a warning message
3367 preceded by "User warning". This warning will always be output, even if
3368 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3369 command line option.
3371 This command may be used to output possible problems when assembling
3380 .warning "Forward jump in jne, cannot optimize!"
3390 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
3391 name=".OUT"></tt> directives.
3394 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3396 Define word sized data. Must be followed by a sequence of (word ranged,
3397 but not necessarily constant) expressions.
3402 .word $0D00, $AF13, _Clear
3406 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3408 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3409 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3413 .segment "ZEROPAGE", zeropage
3416 Because of the "zeropage" attribute, labels declared in this segment are
3417 addressed using direct addressing mode if possible. You <em/must/ instruct
3418 the linker to place this segment somewhere in the address range 0..$FF
3419 otherwise you will get errors.
3421 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3425 <sect>Macros<label id="macros"><p>
3428 <sect1>Introduction<p>
3430 Macros may be thought of as "parametrized super instructions". Macros are
3431 sequences of tokens that have a name. If that name is used in the source
3432 file, the macro is "expanded", that is, it is replaced by the tokens that
3433 were specified when the macro was defined.
3436 <sect1>Macros without parameters<p>
3438 In it's simplest form, a macro does not have parameters. Here's an
3442 .macro asr ; Arithmetic shift right
3443 cmp #$80 ; Put bit 7 into carry
3444 ror ; Rotate right with carry
3448 The macro above consists of two real instructions, that are inserted into
3449 the code, whenever the macro is expanded. Macro expansion is simply done
3450 by using the name, like this:
3459 <sect1>Parametrized macros<p>
3461 When using macro parameters, macros can be even more useful:
3475 When calling the macro, you may give a parameter, and each occurrence of
3476 the name "addr" in the macro definition will be replaced by the given
3495 A macro may have more than one parameter, in this case, the parameters
3496 are separated by commas. You are free to give less parameters than the
3497 macro actually takes in the definition. You may also leave intermediate
3498 parameters empty. Empty parameters are replaced by empty space (that is,
3499 they are removed when the macro is expanded). If you have a look at our
3500 macro definition above, you will see, that replacing the "addr" parameter
3501 by nothing will lead to wrong code in most lines. To help you, writing
3502 macros with a variable parameter list, there are some control commands:
3504 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3505 returns true, if there are any tokens on the remainder of the line. Since
3506 empty parameters are replaced by nothing, this may be used to test if a given
3507 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3510 Look at this example:
3513 .macro ldaxy a, x, y
3526 This macro may be called as follows:
3529 ldaxy 1, 2, 3 ; Load all three registers
3531 ldaxy 1, , 3 ; Load only a and y
3533 ldaxy , , 3 ; Load y only
3536 There's another helper command for determining, which macro parameters are
3537 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3538 replaced by the parameter count given, <em/including/ intermediate empty macro
3542 ldaxy 1 ; .PARAMCOUNT = 1
3543 ldaxy 1,,3 ; .PARAMCOUNT = 3
3544 ldaxy 1,2 ; .PARAMCOUNT = 2
3545 ldaxy 1, ; .PARAMCOUNT = 2
3546 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3549 Macro parameters may optionally be enclosed into curly braces. This allows the
3550 inclusion of tokens that would otherwise terminate the parameter (the comma in
3551 case of a macro parameter).
3554 .macro foo arg1, arg2
3558 foo ($00,x) ; Two parameters passed
3559 foo {($00,x)} ; One parameter passed
3562 In the first case, the macro is called with two parameters: '<tt/($00/'
3563 and 'x)'. The comma is not passed to the macro, since it is part of the
3564 calling sequence, not the parameters.
3566 In the second case, '($00,x)' is passed to the macro, this time
3567 including the comma.
3570 <sect1>Detecting parameter types<p>
3572 Sometimes it is nice to write a macro that acts differently depending on the
3573 type of the argument supplied. An example would be a macro that loads a 16 bit
3574 value from either an immediate operand, or from memory. The <tt/<ref
3575 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3576 functions will allow you to do exactly this:
3580 .if (.match (.left (1, {arg}), #))
3582 lda #<(.right (.tcount ({arg})-1, {arg}))
3583 ldx #>(.right (.tcount ({arg})-1, {arg}))
3585 ; assume absolute or zero page
3592 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3593 check if its argument begins with a hash mark. If so, two immediate loads are
3594 emitted, Otherwise a load from an absolute zero page memory location is
3595 assumed. Please note how the curly braces are used to enclose parameters to
3596 pseudo functions handling token lists. This is necessary, because the token
3597 lists may include commas or parens, which would be treated by the assembler
3600 The macro can be used as
3605 ldax #$1234 ; X=$12, A=$34
3607 ldax foo ; X=$56, A=$78
3611 <sect1>Recursive macros<p>
3613 Macros may be used recursively:
3616 .macro push r1, r2, r3
3625 There's also a special macro to help writing recursive macros: <tt><ref
3626 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3630 .macro push r1, r2, r3, r4, r5, r6, r7
3632 ; First parameter is empty
3638 push r2, r3, r4, r5, r6, r7
3642 When expanding this macro, the expansion will push all given parameters
3643 until an empty one is encountered. The macro may be called like this:
3646 push $20, $21, $32 ; Push 3 ZP locations
3647 push $21 ; Push one ZP location
3651 <sect1>Local symbols inside macros<p>
3653 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3654 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3655 Have a look at the inc16 macro above. Here is it again:
3669 If you have a closer look at the code, you will notice, that it could be
3670 written more efficiently, like this:
3681 But imagine what happens, if you use this macro twice? Since the label
3682 "Skip" has the same name both times, you get a "duplicate symbol" error.
3683 Without a way to circumvent this problem, macros are not as useful, as
3684 they could be. One solution is, to start a new lexical block inside the
3698 Now the label is local to the block and not visible outside. However,
3699 sometimes you want a label inside the macro to be visible outside. To make
3700 that possible, there's a new command that's only usable inside a macro
3701 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3702 or more symbols as local to the macro expansion. The names of local variables
3703 are replaced by a unique name in each separate macro expansion. So we could
3704 also solve the problem above by using <tt/.LOCAL/:
3708 .local Skip ; Make Skip a local symbol
3715 Skip: ; Not visible outside
3720 <sect1>C style macros<p>
3722 Starting with version 2.5 of the assembler, there is a second macro type
3723 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3724 similar to the classic macro type described above, but behaviour is sometimes
3729 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3730 span more than a line. You may use line continuation (see <tt><ref
3731 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3732 more than one line for increased readability, but the macro itself
3733 may not contain an end-of-line token.
3735 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3736 the name space with classic macros, but they are detected and replaced
3737 at the scanner level. While classic macros may be used in every place,
3738 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3739 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3740 they are more versatile in some situations.
3742 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3743 parameters. While classic macros may have empty parameters, this is
3744 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3745 For this macro type, the number of actual parameters must match
3746 exactly the number of formal parameters.
3748 To make this possible, formal parameters are enclosed in braces when
3749 defining the macro. If there are no parameters, the empty braces may
3752 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3753 contain end-of-line tokens, there are things that cannot be done. They
3754 may not contain several processor instructions for example. So, while
3755 some things may be done with both macro types, each type has special
3756 usages. The types complement each other.
3760 Let's look at a few examples to make the advantages and disadvantages
3763 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3764 following <tt/.DEFINE/:
3769 foo EQU $1234 ; This is accepted now
3772 You may use the directive to define string constants used elsewhere:
3775 ; Define the version number
3776 .define VERSION "12.3a"
3782 Macros with parameters may also be useful:
3785 .define DEBUG(message) .out message
3787 DEBUG "Assembling include file #3"
3790 Note that, while formal parameters have to be placed in braces, this is
3791 not true for the actual parameters. Beware: Since the assembler cannot
3792 detect the end of one parameter, only the first token is used. If you
3793 don't like that, use classic macros instead:
3801 (This is an example where a problem can be solved with both macro types).
3804 <sect1>Characters in macros<p>
3806 When using the <ref id="option-t" name="-t"> option, characters are translated
3807 into the target character set of the specific machine. However, this happens
3808 as late as possible. This means that strings are translated if they are part
3809 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3810 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3811 used as part of an expression.
3813 This behaviour is very intuitive outside of macros but may be confusing when
3814 doing more complex macros. If you compare characters against numeric values,
3815 be sure to take the translation into account.
3820 <sect>Macro packages<label id="macropackages"><p>
3822 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3823 macro packages may be included with just one command. Available macro packages
3827 <sect1><tt>.MACPACK generic</tt><p>
3829 This macro package defines macros that are useful in almost any program.
3830 Currently, two macros are defined:
3845 <sect1><tt>.MACPACK longbranch</tt><p>
3847 This macro package defines long conditional jumps. They are named like the
3848 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3849 definition for the "<tt/jeq/" macro, the other macros are built using the same
3854 .if .def(Target) .and ((*+2)-(Target) <= 127)
3863 All macros expand to a short branch, if the label is already defined (back
3864 jump) and is reachable with a short jump. Otherwise the macro expands to a
3865 conditional branch with the branch condition inverted, followed by an absolute
3866 jump to the actual branch target.
3868 The package defines the following macros:
3871 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3876 <sect1><tt>.MACPACK cbm</tt><p>
3878 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3879 string as argument and places this string into memory translated into screen
3883 <sect1><tt>.MACPACK cpu</tt><p>
3885 This macro package does not define any macros but constants used to examine
3886 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3887 each supported CPU a constant similar to
3899 is defined. These constants may be used to determine the exact type of the
3900 currently enabled CPU. In addition to that, for each CPU instruction set,
3901 another constant is defined:
3913 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3914 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3915 currently enabled CPU supports a specific instruction set. For example the
3916 65C02 supports all instructions of the 65SC02 CPU, so it has the
3917 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3921 .if (.cpu .bitand CPU_ISET_65SC02)
3929 it is possible to determine if the
3935 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3936 CPUs (the latter two are upwards compatible to the 65SC02).
3940 <sect>Predefined constants<label id="predefined-constants"><p>
3942 For better orthogonality, the assembler defines similar symbols as the
3943 compiler, depending on the target system selected:
3946 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
3947 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
3948 <item><tt/__ATARI__/ - Target system is <tt/atari/
3949 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
3950 <item><tt/__BBC__/ - Target system is <tt/bbc/
3951 <item><tt/__C128__/ - Target system is <tt/c128/
3952 <item><tt/__C16__/ - Target system is <tt/c16/
3953 <item><tt/__C64__/ - Target system is <tt/c64/
3954 <item><tt/__CBM__/ - Target is a Commodore system
3955 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
3956 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
3957 <item><tt/__GEOS__/ - Target system is <tt/geos/
3958 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
3959 <item><tt/__NES__/ - Target system is <tt/nes/
3960 <item><tt/__PET__/ - Target system is <tt/pet/
3961 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
3962 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
3963 <item><tt/__VIC20__/ - Target system is <tt/vic20/
3967 <sect>Structs and unions<label id="structs"><p>
3969 <sect1>Structs and unions Overview<p>
3971 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3972 are to some degree comparable to their C counterparts. Both have a list of
3973 members. Each member allocates storage and may optionally have a name, which,
3974 in case of a struct, is the offset from the beginning and, in case of a union,
3978 <sect1>Declaration<p>
3980 Here is an example for a very simple struct with two members and a total size
3990 A union shares the total space between all its members, its size is the same
3991 as that of the largest member.
3993 A struct or union must not necessarily have a name. If it is anonymous, no
3994 local scope is opened, the identifiers used to name the members are placed
3995 into the current scope instead.
3997 A struct may contain unnamed members and definitions of local structs. The
3998 storage allocators may contain a multiplier, as in the example below:
4003 .word 2 ; Allocate two words
4010 <sect1>The <tt/.TAG/ keyword<p>
4012 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4013 for an already defined struct or unions within another struct:
4027 Space for a struct or union may be allocated using the <ref id=".TAG"
4028 name=".TAG"> directive.
4034 Currently, members are just offsets from the start of the struct or union. To
4035 access a field of a struct, the member offset has to be added to the address
4036 of the struct itself:
4039 lda C+Circle::Radius ; Load circle radius into A
4042 This may change in a future version of the assembler.
4045 <sect1>Limitations<p>
4047 Structs and unions are currently implemented as nested symbol tables (in fact,
4048 they were a by-product of the improved scoping rules). Currently, the
4049 assembler has no idea of types. This means that the <ref id=".TAG"
4050 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4051 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4052 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4053 this structure accessible by using the '::' operator.
4057 <sect>Module constructors/destructors<label id="condes"><p>
4059 <em>Note:</em> This section applies mostly to C programs, so the explanation
4060 below uses examples from the C libraries. However, the feature may also be
4061 useful for assembler programs.
4064 <sect1>Module constructors/destructors Overview<p>
4066 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4067 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4068 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
4069 special way. The linker is able to generate tables with all functions of a
4070 specific type. Such a table will <em>only</em> include symbols from object
4071 files that are linked into a specific executable. This may be used to add
4072 initialization and cleanup code for library modules, or a table of interrupt
4075 The C heap functions are an example where module initialization code is used.
4076 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4077 variables that contain the start and the end of the heap, pointers to the free
4078 list and so on. Since the end of the heap depends on the size and start of the
4079 stack, it must be initialized at runtime. However, initializing these
4080 variables for programs that do not use the heap are a waste of time and
4083 So the central module defines a function that contains initialization code and
4084 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4085 this module is added to an executable by the linker, the initialization
4086 function will be placed into the table of constructors by the linker. The C
4087 startup code will call all constructors before <tt/main/ and all destructors
4088 after <tt/main/, so without any further work, the heap initialization code is
4089 called once the module is linked in.
4091 While it would be possible to add explicit calls to initialization functions
4092 in the startup code, the new approach has several advantages:
4096 If a module is not included, the initialization code is not linked in and not
4097 called. So you don't pay for things you don't need.
4100 Adding another library that needs initialization does not mean that the
4101 startup code has to be changed. Before we had module constructors and
4102 destructors, the startup code for all systems had to be adjusted to call the
4103 new initialization code.
4106 The feature saves memory: Each additional initialization function needs just
4107 two bytes in the table (a pointer to the function).
4112 <sect1>Calling order<p>
4114 The symbols are sorted in increasing priority order by the linker when using
4115 one of the builtin linker configurations, so the functions with lower
4116 priorities come first and are followed by those with higher priorities. The C
4117 library runtime subroutine that walks over the function tables calls the
4118 functions starting from the top of the table - which means that functions with
4119 a high priority are called first.
4121 So when using the C runtime, functions are called with high priority functions
4122 first, followed by low priority functions.
4127 When using these special symbols, please take care of the following:
4132 The linker will only generate function tables, it will not generate code to
4133 call these functions. If you're using the feature in some other than the
4134 existing C environments, you have to write code to call all functions in a
4135 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4136 in the C runtime for an example on how to do this.
4139 The linker will only add addresses of functions that are in modules linked to
4140 the executable. This means that you have to be careful where to place the
4141 condes functions. If initialization or an irq handler is needed for a group of
4142 functions, be sure to place the function into a module that is linked in
4143 regardless of which function is called by the user.
4146 The linker will generate the tables only when requested to do so by the
4147 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4148 be requested separately.
4151 Constructors and destructors may have priorities. These priorities determine
4152 the order of the functions in the table. If your initialization or cleanup code
4153 does depend on other initialization or cleanup code, you have to choose the
4154 priority for the functions accordingly.
4157 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4158 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4159 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4160 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4161 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4162 (interruptor). The linker generates a separate table for each type on request.
4167 <sect>Porting sources from other assemblers<p>
4169 Sometimes it is necessary to port code written for older assemblers to ca65.
4170 In some cases, this can be done without any changes to the source code by
4171 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4172 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4175 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4176 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4177 done by the linker. Most other assemblers generate absolute code, placement is
4178 done within the assembler and there is no external linker.
4180 In general it is not a good idea to write new code using the emulation
4181 features of the assembler, but there may be situations where even this rule is
4186 You need to use some of the ca65 emulation features to simulate the behaviour
4187 of such simple assemblers.
4190 <item>Prepare your sourcecode like this:
4193 ; if you want TASS style labels without colons
4194 .feature labels_without_colons
4196 ; if you want TASS style character constants
4197 ; ("a" instead of the default 'a')
4198 .feature loose_char_term
4200 .word *+2 ; the cbm load address
4205 notice that the two emulation features are mostly useful for porting
4206 sources originally written in/for TASS, they are not needed for the
4207 actual "simple assembler operation" and are not recommended if you are
4208 writing new code from scratch.
4210 <item>Replace all program counter assignments (which are not possible in ca65
4211 by default, and the respective emulation feature works different from what
4212 you'd expect) by another way to skip to memory locations, for example the
4213 <tt><ref id=".RES" name=".RES"></tt> directive.
4217 .res $2000-* ; reserve memory up to $2000
4220 Please note that other than the original TASS, ca65 can never move the program
4221 counter backwards - think of it as if you are assembling to disk with TASS.
4223 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4224 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4225 of <tt/.goto/, everything involving loops must be replaced by
4226 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4228 <item>To assemble code to a different address than it is executed at, use the
4229 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4230 <tt/.offs/-constructs.
4237 .reloc ; back to normal
4240 <item>Then assemble like this:
4243 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4246 Note that you need to use the actual start address minus two, since two bytes
4247 are used for the cbm load address.
4252 <sect>Bugs/Feedback<p>
4254 If you have problems using the assembler, if you find any bugs, or if
4255 you're doing something interesting with the assembler, I would be glad to
4256 hear from you. Feel free to contact me by email
4257 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4263 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4264 Bassewitz. For usage of the binaries and/or sources the following
4265 conditions do apply:
4267 This software is provided 'as-is', without any expressed or implied
4268 warranty. In no event will the authors be held liable for any damages
4269 arising from the use of this software.
4271 Permission is granted to anyone to use this software for any purpose,
4272 including commercial applications, and to alter it and redistribute it
4273 freely, subject to the following restrictions:
4276 <item> The origin of this software must not be misrepresented; you must not
4277 claim that you wrote the original software. If you use this software
4278 in a product, an acknowledgment in the product documentation would be
4279 appreciated but is not required.
4280 <item> Altered source versions must be plainly marked as such, and must not
4281 be misrepresented as being the original software.
4282 <item> This notice may not be removed or altered from any source