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>The value of the environment variable <tt/CA65_INC/ if it is defined.
319 <item>A subdirectory named <tt/asminc/ of the directory defined in the
320 environment variable <tt/CC65_HOME/, if it is defined.
321 <item>Any directory added with the <tt/-I/ option on the command line.
326 <sect>Input format<p>
328 <sect1>Assembler syntax<p>
330 The assembler accepts the standard 6502/65816 assembler syntax. One line may
331 contain a label (which is identified by a colon), and, in addition to the
332 label, an assembler mnemonic, a macro, or a control command (see section <ref
333 id="control-commands" name="Control Commands"> for supported control
334 commands). Alternatively, the line may contain a symbol definition using
335 the '=' token. Everything after a semicolon is handled as a comment (that is,
338 Here are some examples for valid input lines:
341 Label: ; A label and a comment
342 lda #$20 ; A 6502 instruction plus comment
343 L1: ldx #$20 ; Same with label
344 L2: .byte "Hello world" ; Label plus control command
345 mymac $20 ; Macro expansion
346 MySym = 3*L1 ; Symbol definition
347 MaSym = Label ; Another symbol
350 The assembler accepts
353 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
354 <tt><ref id=".P02" name=".P02"></tt> command was given).
355 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
356 <ref id="6502X-mode" name="6502X mode">.
357 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
358 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
359 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
360 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
361 <item>all valid 65618 mnemonics when in 65816 mode (after the
362 <tt><ref id=".P816" name=".P816"></tt> command was given).
363 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
364 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
370 In 65816 mode several aliases are accepted in addition to the official
374 BGE is an alias for BCS
375 BLT is an alias for BCC
376 CPA is an alias for CMP
377 DEA is an alias for DEC A
378 INA is an alias for INC A
379 SWA is an alias for XBA
380 TAD is an alias for TCD
381 TAS is an alias for TCS
382 TDA is an alias for TDC
383 TSA is an alias for TSC
388 <sect1>6502X mode<label id="6502X-mode"><p>
390 6502X mode is an extension to the normal 6502 mode. In this mode, several
391 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
392 these instructions are illegal, there are no official mnemonics for them. The
393 unofficial ones are taken from <htmlurl
394 url="http://oxyron.net/graham/opcodes02.html"
395 name="http://oxyron.net/graham/opcodes02.html">. Please note that only the
396 ones marked as "stable" are supported. The following table uses information
397 from the mentioned web page, for more information, see there.
400 <item><tt>ALR: A:=(A and #{imm})*2;</tt>
401 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
402 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
403 <item><tt>AXS: X:=A and X-#{imm};</tt>
404 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
405 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
406 <item><tt>LAS: A,X,S:={adr} and S;</tt>
407 <item><tt>LAX: A,X:={adr};</tt>
408 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
409 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
410 <item><tt>SAX: {adr}:=A and X;</tt>
411 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
412 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
417 <sect1>sweet16 mode<label id="sweet16-mode"><p>
419 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
420 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
421 generate code for this pseudo CPU when switched into sweet16 mode. The
422 following is special in sweet16 mode:
426 <item>The '@' character denotes indirect addressing and is no longer available
427 for cheap local labels. If you need cheap local labels, you will have to
428 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
429 name=".LOCALCHAR">/ command.
431 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
432 these identifiers are reserved words.
436 Please note that the assembler does neither supply the interpreter needed for
437 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
438 nor does it call the interpreter. All this must be done by your program. Apple
439 ][ programmers do probably know how to use sweet16 mode.
441 For more information about SWEET 16, see
442 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
443 name="http://www.6502.org/source/interpreters/sweet16.htm">.
446 <sect1>Number format<p>
448 For literal values, the assembler accepts the widely used number formats: A
449 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
450 denotes a binary value, and a bare number is interpreted as a decimal. There
451 are currently no octal values and no floats.
454 <sect1>Conditional assembly<p>
456 Please note that when using the conditional directives (<tt/.IF/ and friends),
457 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
458 that are not assembled. The reason for this behaviour is that the assembler
459 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
460 conversion of the input stream into tokens still takes place. As a consequence
461 conditional assembly directives may <bf/not/ be used to prevent normal text
462 (used as a comment or similar) from being assembled. <p>
468 <sect1>Expression evaluation<p>
470 All expressions are evaluated with (at least) 32 bit precision. An
471 expression may contain constant values and any combination of internal and
472 external symbols. Expressions that cannot be evaluated at assembly time
473 are stored inside the object file for evaluation by the linker.
474 Expressions referencing imported symbols must always be evaluated by the
478 <sect1>Size of an expression result<p>
480 Sometimes, the assembler must know about the size of the value that is the
481 result of an expression. This is usually the case, if a decision has to be
482 made, to generate a zero page or an absolute memory references. In this
483 case, the assembler has to make some assumptions about the result of an
487 <item> If the result of an expression is constant, the actual value is
488 checked to see if it's a byte sized expression or not.
489 <item> If the expression is explicitly casted to a byte sized expression by
490 one of the '>', '<' or '^' operators, it is a byte expression.
491 <item> If this is not the case, and the expression contains a symbol,
492 explicitly declared as zero page symbol (by one of the .importzp or
493 .exportzp instructions), then the whole expression is assumed to be
495 <item> If the expression contains symbols that are not defined, and these
496 symbols are local symbols, the enclosing scopes are searched for a
497 symbol with the same name. If one exists and this symbol is defined,
498 it's attributes are used to determine the result size.
499 <item> In all other cases the expression is assumed to be word sized.
502 Note: If the assembler is not able to evaluate the expression at assembly
503 time, the linker will evaluate it and check for range errors as soon as
507 <sect1>Boolean expressions<p>
509 In the context of a boolean expression, any non zero value is evaluated as
510 true, any other value to false. The result of a boolean expression is 1 if
511 it's true, and zero if it's false. There are boolean operators with extreme
512 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
513 operators are shortcut operators. That is, if the result of the expression is
514 already known, after evaluating the left hand side, the right hand side is
518 <sect1>Constant expressions<p>
520 Sometimes an expression must evaluate to a constant without looking at any
521 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
522 that decides if parts of the code are assembled or not. An expression used in
523 the <tt/.IF/ command cannot reference a symbol defined later, because the
524 decision about the <tt/.IF/ must be made at the point when it is read. If the
525 expression used in such a context contains only constant numerical values,
526 there is no problem. When unresolvable symbols are involved it may get harder
527 for the assembler to determine if the expression is actually constant, and it
528 is even possible to create expressions that aren't recognized as constant.
529 Simplifying the expressions will often help.
531 In cases where the result of the expression is not needed immediately, the
532 assembler will delay evaluation until all input is read, at which point all
533 symbols are known. So using arbitrary complex constant expressions is no
534 problem in most cases.
538 <sect1>Available operators<label id="operators"><p>
542 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
543 | Built-in string functions| 0@
545 | Built-in pseudo-variables| 1@
546 | Built-in pseudo-functions| 1@
547 +| Unary positive| 1@
548 -| Unary negative| 1@
550 .BITNOT| Unary bitwise not| 1@
552 .LOBYTE| Unary low-byte operator| 1@
554 .HIBYTE| Unary high-byte operator| 1@
556 .BANKBYTE| Unary bank-byte operator| 1@
558 *| Multiplication| 2@
560 .MOD| Modulo operator| 2@
562 .BITAND| Bitwise and| 2@
564 .BITXOR| Binary bitwise xor| 2@
566 .SHL| Shift-left operator| 2@
568 .SHR| Shift-right operator| 2@
570 +| Binary addition| 3@
571 -| Binary subtraction| 3@
573 .BITOR| Bitwise or| 3@
575 = | Compare operator (equal)| 4@
576 <>| Compare operator (not equal)| 4@
577 <| Compare operator (less)| 4@
578 >| Compare operator (greater)| 4@
579 <=| Compare operator (less or equal)| 4@
580 >=| Compare operator (greater or equal)| 4@
583 .AND| Boolean and| 5@
584 .XOR| Boolean xor| 5@
586 ||<newline>
590 .NOT| Boolean not| 7@<hline>
592 <caption>Available operators, sorted by precedence
595 To force a specific order of evaluation, parentheses may be used, as usual.
599 <sect>Symbols and labels<p>
601 A symbol or label is an identifier that starts with a letter and is followed
602 by letters and digits. Depending on some features enabled (see
603 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
604 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
605 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
606 other characters may be present. Use of identifiers consisting of a single
607 character will not work in all cases, because some of these identifiers are
608 reserved keywords (for example "A" is not a valid identifier for a label,
609 because it is the keyword for the accumulator).
611 The assembler allows you to use symbols instead of naked values to make
612 the source more readable. There are a lot of different ways to define and
613 use symbols and labels, giving a lot of flexibility.
615 <sect1>Numeric constants<p>
617 Numeric constants are defined using the equal sign or the label assignment
618 operator. After doing
624 may use the symbol "two" in every place where a number is expected, and it is
625 evaluated to the value 2 in this context. The label assignment operator causes
626 the same, but causes the symbol to be marked as a label, which may cause a
627 different handling in the debugger:
633 The right side can of course be an expression:
640 <sect1>Standard labels<p>
642 A label is defined by writing the name of the label at the start of the line
643 (before any instruction mnemonic, macro or pseudo directive), followed by a
644 colon. This will declare a symbol with the given name and the value of the
645 current program counter.
648 <sect1>Local labels and symbols<p>
650 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
651 create regions of code where the names of labels and symbols are local to this
652 region. They are not known outside of this region and cannot be accessed from
653 there. Such regions may be nested like PROCEDUREs in Pascal.
655 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
656 directive for more information.
659 <sect1>Cheap local labels<p>
661 Cheap local labels are defined like standard labels, but the name of the
662 label must begin with a special symbol (usually '@', but this can be
663 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
666 Cheap local labels are visible only between two non cheap labels. As soon as a
667 standard symbol is encountered (this may also be a local symbol if inside a
668 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
669 cheap local symbol goes out of scope.
671 You may use cheap local labels as an easy way to reuse common label
672 names like "Loop". Here is an example:
675 Clear: lda #$00 ; Global label
677 @Loop: sta Mem,y ; Local label
681 Sub: ... ; New global label
682 bne @Loop ; ERROR: Unknown identifier!
685 <sect1>Unnamed labels<p>
687 If you really want to write messy code, there are also unnamed labels. These
688 labels do not have a name (you guessed that already, didn't you?). A colon is
689 used to mark the absence of the name.
691 Unnamed labels may be accessed by using the colon plus several minus or plus
692 characters as a label designator. Using the '-' characters will create a back
693 reference (use the n'th label backwards), using '+' will create a forward
694 reference (use the n'th label in forward direction). An example will help to
717 As you can see from the example, unnamed labels will make even short
718 sections of code hard to understand, because you have to count labels
719 to find branch targets (this is the reason why I for my part do
720 prefer the "cheap" local labels). Nevertheless, unnamed labels are
721 convenient in some situations, so it's your decision.
724 <sect1>Using macros to define labels and constants<p>
726 While there are drawbacks with this approach, it may be handy in some
727 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
728 possible to define symbols or constants that may be used elsewhere. Since
729 the macro facility works on a very low level, there is no scoping. On the
730 other side, you may also define string constants this way (this is not
731 possible with the other symbol types).
737 .DEFINE version "SOS V2.3"
739 four = two * two ; Ok
742 .PROC ; Start local scope
743 two = 3 ; Will give "2 = 3" - invalid!
748 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
750 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
751 id="option-g" name="-g"> is given on the command line), global, local and
752 cheap local labels are written to the object file and will be available in the
753 symbol file via the linker. Unnamed labels are not written to the object file,
754 because they don't have a name which would allow to access them.
758 <sect>Scopes<label id="scopes"><p>
760 ca65 implements several sorts of scopes for symbols.
762 <sect1>Global scope<p>
764 All (non cheap local) symbols that are declared outside of any nested scopes
768 <sect1>Cheap locals<p>
770 A special scope is the scope for cheap local symbols. It lasts from one non
771 local symbol to the next one, without any provisions made by the programmer.
772 All other scopes differ in usage but use the same concept internally.
775 <sect1>Generic nested scopes<p>
777 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
778 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
779 The scope can have a name, in which case it is accessible from the outside by
780 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
781 have a name, all symbols created within the scope are local to the scope, and
782 aren't accessible from the outside.
784 A nested scope can access symbols from the local or from enclosing scopes by
785 name without using explicit scope names. In some cases there may be
786 ambiguities, for example if there is a reference to a local symbol that is not
787 yet defined, but a symbol with the same name exists in outer scopes:
799 In the example above, the <tt/lda/ instruction will load the value 3 into the
800 accumulator, because <tt/foo/ is redefined in the scope. However:
812 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
813 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
814 absolute mode is used instead. In fact, the assembler will not use absolute
815 mode by default, but it will search through the enclosing scopes for a symbol
816 with the given name. If one is found, the address size of this symbol is used.
817 This may lead to errors:
829 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
830 instruction, it will search for an already defined symbol <tt/foo/. It will
831 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
832 zeropage symbol. So the assembler will use zeropage addressing mode. If
833 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
834 the address in the <tt/lda/ instruction already translated, but since the new
835 value needs absolute addressing mode, this fails, and an error message "Range
838 Of course the most simple solution for the problem is to move the definition
839 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
840 rare cases when this cannot be done. In these cases, you can use one of the
841 address size override operators:
853 This will cause the <tt/lda/ instruction to be translated using absolute
854 addressing mode, which means changing the symbol reference later does not
858 <sect1>Nested procedures<p>
860 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
861 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
862 name, and a it will introduce a symbol with this name in the enclosing scope.
871 is actually the same as
880 This is the reason why a procedure must have a name. If you want a scope
881 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
883 <bf/Note:/ As you can see from the example above, scopes and symbols live in
884 different namespaces. There can be a symbol named <tt/foo/ and a scope named
885 <tt/foo/ without any conflicts (but see the section titled <ref
886 id="scopesearch" name=""Scope search order"">).
889 <sect1>Structs, unions and enums<p>
891 Structs, unions and enums are explained in a <ref id="structs" name="separate
892 section">, I do only cover them here, because if they are declared with a
893 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
894 name=".SCOPE">/. However, when no name is specified, the behaviour is
895 different: In this case, no new scope will be opened, symbols declared within
896 a struct, union, or enum declaration will then be added to the enclosing scope
900 <sect1>Explicit scope specification<label id="scopesyntax"><p>
902 Accessing symbols from other scopes is possible by using an explicit scope
903 specification, provided that the scope where the symbol lives in has a name.
904 The namespace token (<tt/::/) is used to access other scopes:
912 lda foo::bar ; Access foo in scope bar
915 The only way to deny access to a scope from the outside is to declare a scope
916 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
918 A special syntax is used to specify the global scope: If a symbol or scope is
919 preceded by the namespace token, the global scope is searched:
926 lda #::bar ; Access the global bar (which is 3)
931 <sect1>Scope search order<label id="scopesearch"><p>
933 The assembler searches for a scope in a similar way as for a symbol. First, it
934 looks in the current scope, and then it walks up the enclosing scopes until
937 However, one important thing to note when using explicit scope syntax is, that
938 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
939 used without a preceding definition. This means that in the following
948 lda #foo::bar ; Will load 3, not 2!
955 the reference to the scope <tt/foo/ will use the global scope, and not the
956 local one, because the local one is not visible at the point where it is
959 Things get more complex if a complete chain of scopes is specified:
970 lda #outer::inner::bar ; 1
982 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
983 assembler will first search in the local scope for a scope named <tt/outer/.
984 Since none is found, the enclosing scope (<tt/another/) is checked. There is
985 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
986 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
987 this scope, the assembler looks for a symbol named <tt/bar/.
989 Please note that once the anchor scope is found, all following scopes
990 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
991 assembler will search the scope tree only for the first scope (if it is not
992 anchored in the root scope). Starting from there on, there is no flexibility,
993 so if the scope named <tt/outer/ found by the assembler does not contain a
994 scope named <tt/inner/, this would be an error, even if such a pair does exist
995 (one level up in global scope).
997 Ambiguities that may be introduced by this search algorithm may be removed by
998 anchoring the scope specification in the global scope. In the example above,
999 if you want to access the "other" symbol <tt/bar/, you would have to write:
1010 lda #::outer::inner::bar ; 2
1023 <sect>Address sizes and memory models<label id="address-sizes"><p>
1025 <sect1>Address sizes<p>
1027 ca65 assigns each segment and each symbol an address size. This is true, even
1028 if the symbol is not used as an address. You may also think of a value range
1029 of the symbol instead of an address size.
1031 Possible address sizes are:
1034 <item>Zeropage or direct (8 bits)
1035 <item>Absolute (16 bits)
1037 <item>Long (32 bits)
1040 Since the assembler uses default address sizes for the segments and symbols,
1041 it is usually not necessary to override the default behaviour. In cases, where
1042 it is necessary, the following keywords may be used to specify address sizes:
1045 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1046 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1047 <item>FAR for far addressing (24 bits).
1048 <item>LONG or DWORD for long addressing (32 bits).
1052 <sect1>Address sizes of segments<p>
1054 The assembler assigns an address size to each segment. Since the
1055 representation of a label within this segment is "segment start + offset",
1056 labels will inherit the address size of the segment they are declared in.
1058 The address size of a segment may be changed, by using an optional address
1059 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1060 an explanation on how this is done.
1063 <sect1>Address sizes of symbols<p>
1068 <sect1>Memory models<p>
1070 The default address size of a segment depends on the memory model used. Since
1071 labels inherit the address size from the segment they are declared in,
1072 changing the memory model is an easy way to change the address size of many
1078 <sect>Pseudo variables<label id="pseudo-variables"><p>
1080 Pseudo variables are readable in all cases, and in some special cases also
1083 <sect1><tt>*</tt><p>
1085 Reading this pseudo variable will return the program counter at the start
1086 of the current input line.
1088 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1089 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1090 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1093 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1095 Reading this pseudo variable will give a constant integer value that
1096 tells which CPU is currently enabled. It can also tell which instruction
1097 set the CPU is able to translate. The value read from the pseudo variable
1098 should be further examined by using one of the constants defined by the
1099 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1101 It may be used to replace the .IFPxx pseudo instructions or to construct
1102 even more complex expressions.
1108 .if (.cpu .bitand CPU_ISET_65816)
1120 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1122 This builtin pseudo variable is only available in macros. It is replaced by
1123 the actual number of parameters that were given in the macro invocation.
1128 .macro foo arg1, arg2, arg3
1129 .if .paramcount <> 3
1130 .error "Too few parameters for macro foo"
1136 See section <ref id="macros" name="Macros">.
1139 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1141 Reading this pseudo variable will give a constant integer value that
1142 represents the current time in POSIX standard (as seconds since the
1145 It may be used to encode the time of translation somewhere in the created
1151 .dword .time ; Place time here
1155 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1157 Reading this pseudo variable will give the assembler version according to
1158 the following formula:
1160 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1162 It may be used to encode the assembler version or check the assembler for
1163 special features not available with older versions.
1167 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1168 reading the pseudo variable <tt/.VERSION/.
1172 <sect>Pseudo functions<label id="pseudo-functions"><p>
1174 Pseudo functions expect their arguments in parenthesis, and they have a result,
1175 either a string or an expression.
1178 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1180 The function returns the bank byte (that is, bits 16-23) of its argument.
1181 It works identical to the '^' operator.
1183 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1184 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1187 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1189 Builtin function. The function evaluates its argument in braces and yields
1190 "false" if the argument is non blank (there is an argument), and "true" if
1191 there is no argument. The token list that makes up the function argument
1192 may optionally be enclosed in curly braces. This allows the inclusion of
1193 tokens that would otherwise terminate the list (the closing right
1194 parenthesis). The curly braces are not considered part of the list, a list
1195 just consisting of curly braces is considered to be empty.
1197 As an example, the <tt/.IFBLANK/ statement may be replaced by
1205 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1207 Builtin string function. The function allows to concatenate a list of string
1208 constants separated by commas. The result is a string constant that is the
1209 concatenation of all arguments. This function is most useful in macros and
1210 when used together with the <tt/.STRING/ builtin function. The function may
1211 be used in any case where a string constant is expected.
1216 .include .concat ("myheader", ".", "inc")
1219 This is the same as the command
1222 .include "myheader.inc"
1226 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1228 Builtin function. The function evaluates its argument in braces and
1229 yields "true" if the argument is a constant expression (that is, an
1230 expression that yields a constant value at assembly time) and "false"
1231 otherwise. As an example, the .IFCONST statement may be replaced by
1238 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1240 The function returns the high byte (that is, bits 8-15) of its argument.
1241 It works identical to the '>' operator.
1243 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1244 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1247 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1249 The function returns the high word (that is, bits 16-31) of its argument.
1251 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1254 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1256 The function expects a string as its argument, and converts this argument
1257 into an identifier. If the string starts with the current <tt/<ref
1258 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1259 identifier, otherwise it will be converted into a normal identifier.
1264 .macro makelabel arg1, arg2
1265 .ident (.concat (arg1, arg2)):
1268 makelabel "foo", "bar"
1270 .word foobar ; Valid label
1274 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1276 Builtin function. Extracts the left part of a given token list.
1281 .LEFT (<int expr>, <token list>)
1284 The first integer expression gives the number of tokens to extract from
1285 the token list. The second argument is the token list itself. The token
1286 list may optionally be enclosed into curly braces. This allows the
1287 inclusion of tokens that would otherwise terminate the list (the closing
1288 right paren in the given case).
1292 To check in a macro if the given argument has a '#' as first token
1293 (immediate addressing mode), use something like this:
1298 .if (.match (.left (1, {arg}), #))
1300 ; ldax called with immediate operand
1308 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1309 name=".RIGHT"></tt> builtin functions.
1312 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1314 The function returns the low byte (that is, bits 0-7) of its argument.
1315 It works identical to the '<' operator.
1317 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1318 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1321 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1323 The function returns the low word (that is, bits 0-15) of its argument.
1325 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1328 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1330 Builtin function. Matches two token lists against each other. This is
1331 most useful within macros, since macros are not stored as strings, but
1337 .MATCH(<token list #1>, <token list #2>)
1340 Both token list may contain arbitrary tokens with the exception of the
1341 terminator token (comma resp. right parenthesis) and
1348 The token lists may optionally be enclosed into curly braces. This allows
1349 the inclusion of tokens that would otherwise terminate the list (the closing
1350 right paren in the given case). Often a macro parameter is used for any of
1353 Please note that the function does only compare tokens, not token
1354 attributes. So any number is equal to any other number, regardless of the
1355 actual value. The same is true for strings. If you need to compare tokens
1356 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1357 name=".XMATCH"></tt> function.
1361 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1362 while honoring the sign bit. The builtin processor instructions will allow
1363 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1364 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1365 to check for this and print and error for invalid calls.
1370 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1371 .error "Syntax error"
1374 cmp #$80 ; Bit 7 into carry
1375 lsr a ; Shift carry into bit 7
1380 The macro will only accept no arguments, or one argument that must be the
1381 reserved keyword "A".
1383 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1386 <sect1><tt>.MID</tt><label id=".MID"><p>
1388 Builtin function. Takes a starting index, a count and a token list as
1389 arguments. Will return part of the token list.
1394 .MID (<int expr>, <int expr>, <token list>)
1397 The first integer expression gives the starting token in the list (the first
1398 token has index 0). The second integer expression gives the number of tokens
1399 to extract from the token list. The third argument is the token list itself.
1400 The token list may optionally be enclosed into curly braces. This allows the
1401 inclusion of tokens that would otherwise terminate the list (the closing
1402 right paren in the given case).
1406 To check in a macro if the given argument has a '<tt/#/' as first token
1407 (immediate addressing mode), use something like this:
1412 .if (.match (.mid (0, 1, {arg}), #))
1414 ; ldax called with immediate operand
1422 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1423 name=".RIGHT"></tt> builtin functions.
1426 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1428 Builtin function. The function expects an identifier as argument in braces.
1429 The argument is evaluated, and the function yields "true" if the identifier
1430 is a symbol that has already been referenced somewhere in the source file up
1431 to the current position. Otherwise the function yields false. As an example,
1432 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1438 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1441 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1443 Builtin function. Extracts the right part of a given token list.
1448 .RIGHT (<int expr>, <token list>)
1451 The first integer expression gives the number of tokens to extract from the
1452 token list. The second argument is the token list itself. The token list
1453 may optionally be enclosed into curly braces. This allows the inclusion of
1454 tokens that would otherwise terminate the list (the closing right paren in
1457 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1458 name=".MID"></tt> builtin functions.
1461 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1463 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1464 argument can be a struct/union, a struct member, a procedure, or a label. In
1465 case of a procedure or label, its size is defined by the amount of data
1466 placed in the segment where the label is relative to. If a line of code
1467 switches segments (for example in a macro) data placed in other segments
1468 does not count for the size.
1470 Please note that a symbol or scope must exist, before it is used together with
1471 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1472 A scope has preference over a symbol with the same name, so if the last part
1473 of a name represents both, a scope and a symbol, the scope is chosen over the
1476 After the following code:
1479 .struct Point ; Struct size = 4
1484 P: .tag Point ; Declare a point
1485 @P: .tag Point ; Declare another point
1497 .data ; Segment switch!!!
1503 <tag><tt/.sizeof(Point)/</tag>
1504 will have the value 4, because this is the size of struct <tt/Point/.
1506 <tag><tt/.sizeof(Point::xcoord)/</tag>
1507 will have the value 2, because this is the size of the member <tt/xcoord/
1508 in struct <tt/Point/.
1510 <tag><tt/.sizeof(P)/</tag>
1511 will have the value 4, this is the size of the data declared on the same
1512 source line as the label <tt/P/, which is in the same segment that <tt/P/
1515 <tag><tt/.sizeof(@P)/</tag>
1516 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1517 does also work for cheap local symbols.
1519 <tag><tt/.sizeof(Code)/</tag>
1520 will have the value 3, since this is amount of data emitted into the code
1521 segment, the segment that was active when <tt/Code/ was entered. Note that
1522 this value includes the amount of data emitted in child scopes (in this
1523 case <tt/Code::Inner/).
1525 <tag><tt/.sizeof(Code::Inner)/</tag>
1526 will have the value 1 as expected.
1528 <tag><tt/.sizeof(Data)/</tag>
1529 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1530 the segment is switched after entry, this data is emitted into another
1535 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1537 Builtin function. The function accepts a string and an index as
1538 arguments and returns the value of the character at the given position
1539 as an integer value. The index is zero based.
1545 ; Check if the argument string starts with '#'
1546 .if (.strat (Arg, 0) = '#')
1553 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1555 Builtin function. It expects a format string as first argument. The number
1556 and type of the following arguments depend on the format string. The format
1557 string is similar to the one of the C <tt/printf/ function. Missing things
1558 are: Length modifiers, variable width.
1560 The result of the function is a string.
1567 ; Generate an identifier:
1568 .ident (.sprintf ("%s%03d", "label", num)):
1572 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1574 Builtin function. The function accepts an argument in braces and converts
1575 this argument into a string constant. The argument may be an identifier, or
1576 a constant numeric value.
1578 Since you can use a string in the first place, the use of the function may
1579 not be obvious. However, it is useful in macros, or more complex setups.
1584 ; Emulate other assemblers:
1586 .segment .string(name)
1591 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1593 Builtin function. The function accepts a string argument in braces and
1594 evaluates to the length of the string.
1598 The following macro encodes a string as a pascal style string with
1599 a leading length byte.
1603 .byte .strlen(Arg), Arg
1608 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1610 Builtin function. The function accepts a token list in braces. The function
1611 result is the number of tokens given as argument. The token list may
1612 optionally be enclosed into curly braces which are not considered part of
1613 the list and not counted. Enclosement in curly braces allows the inclusion
1614 of tokens that would otherwise terminate the list (the closing right paren
1619 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1620 with the normal 6502 instructions). To translate it into two separate 8 bit
1621 load instructions, the '#' token has to get stripped from the argument:
1625 .if (.match (.mid (0, 1, {arg}), #))
1626 ; ldax called with immediate operand
1627 lda #<(.right (.tcount ({arg})-1, {arg}))
1628 ldx #>(.right (.tcount ({arg})-1, {arg}))
1636 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1638 Builtin function. Matches two token lists against each other. This is
1639 most useful within macros, since macros are not stored as strings, but
1645 .XMATCH(<token list #1>, <token list #2>)
1648 Both token list may contain arbitrary tokens with the exception of the
1649 terminator token (comma resp. right parenthesis) and
1656 The token lists may optionally be enclosed into curly braces. This allows
1657 the inclusion of tokens that would otherwise terminate the list (the closing
1658 right paren in the given case). Often a macro parameter is used for any of
1661 The function compares tokens <em/and/ token values. If you need a function
1662 that just compares the type of tokens, have a look at the <tt><ref
1663 id=".MATCH" name=".MATCH"></tt> function.
1665 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1669 <sect>Control commands<label id="control-commands"><p>
1671 Here's a list of all control commands and a description, what they do:
1674 <sect1><tt>.A16</tt><label id=".A16"><p>
1676 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1678 Note: This command will not emit any code, it will tell the assembler to
1679 create 16 bit operands for immediate accumulator addressing mode.
1681 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1684 <sect1><tt>.A8</tt><label id=".A8"><p>
1686 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1688 Note: This command will not emit any code, it will tell the assembler to
1689 create 8 bit operands for immediate accu addressing mode.
1691 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1694 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1696 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1697 may be used for better readability if the data words are address values. In
1698 65816 mode, the address is forced to be 16 bit wide to fit into the current
1699 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1700 must be followed by a sequence of (not necessarily constant) expressions.
1705 .addr $0D00, $AF13, _Clear
1708 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1712 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1714 Align data to a given boundary. The command expects a constant integer
1715 argument that must be a power of two, plus an optional second argument
1716 in byte range. If there is a second argument, it is used as fill value,
1717 otherwise the value defined in the linker configuration file is used
1718 (the default for this value is zero).
1720 Since alignment depends on the base address of the module, you must
1721 give the same (or a greater) alignment for the segment when linking.
1722 The linker will give you a warning, if you don't do that.
1731 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1733 Define a string with a trailing zero.
1738 Msg: .asciiz "Hello world"
1741 This will put the string "Hello world" followed by a binary zero into
1742 the current segment. There may be more strings separated by commas, but
1743 the binary zero is only appended once (after the last one).
1746 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1748 Add an assertion. The command is followed by an expression, an action
1749 specifier, and an optional message that is output in case the assertion
1750 fails. If no message was given, the string "Assertion failed" is used. The
1751 action specifier may be one of <tt/warning/ or <tt/error/. The assertion is
1752 evaluated by the assembler if possible, and also passed to the linker in the
1753 object file (if one is generated). The linker will then evaluate the
1754 expression when segment placement has been done.
1759 .assert * = $8000, error, "Code not at $8000"
1762 The example assertion will check that the current location is at $8000,
1763 when the output file is written, and abort with an error if this is not
1764 the case. More complex expressions are possible. The action specifier
1765 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1766 an error message. In the latter case, generation of the output file is
1767 suppressed in both the assembler and linker.
1770 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1772 Is followed by a plus or a minus character. When switched on (using a
1773 +), undefined symbols are automatically marked as import instead of
1774 giving errors. When switched off (which is the default so this does not
1775 make much sense), this does not happen and an error message is
1776 displayed. The state of the autoimport flag is evaluated when the
1777 complete source was translated, before outputting actual code, so it is
1778 <em/not/ possible to switch this feature on or off for separate sections
1779 of code. The last setting is used for all symbols.
1781 You should probably not use this switch because it delays error
1782 messages about undefined symbols until the link stage. The cc65
1783 compiler (which is supposed to produce correct assembler code in all
1784 circumstances, something which is not true for most assembler
1785 programmers) will insert this command to avoid importing each and every
1786 routine from the runtime library.
1791 .autoimport + ; Switch on auto import
1794 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
1796 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
1797 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
1798 the operator '^' prepended to each expression in its list.
1803 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
1805 TableLookupLo: .lobytes MyTable
1806 TableLookupHi: .hibytes MyTable
1807 TableLookupBank: .bankbytes MyTable
1810 which is equivalent to
1813 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
1814 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
1815 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
1818 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
1819 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
1820 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
1823 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1825 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1826 so this is a shortcut for
1832 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1835 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1837 Define byte sized data. Must be followed by a sequence of (byte ranged)
1838 expressions or strings.
1844 .byt "world", $0D, $00
1848 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1850 Switch on or off case sensitivity on identifiers. The default is off
1851 (that is, identifiers are case sensitive), but may be changed by the
1852 -i switch on the command line.
1853 The command must be followed by a '+' or '-' character to switch the
1854 option on or off respectively.
1859 .case - ; Identifiers are not case sensitive
1863 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1865 Apply a custom mapping for characters. The command is followed by two
1866 numbers in the range 1..255. The first one is the index of the source
1867 character, the second one is the mapping. The mapping applies to all
1868 character and string constants when they generate output, and overrides
1869 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1870 command line switch.
1875 .charmap $41, $61 ; Map 'A' to 'a'
1879 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1881 Switch to the CODE segment. The name of the CODE segment is always
1882 "CODE", so this is a shortcut for
1888 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1891 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1893 Export a symbol and mark it in a special way. The linker is able to build
1894 tables of all such symbols. This may be used to automatically create a list
1895 of functions needed to initialize linked library modules.
1897 Note: The linker has a feature to build a table of marked routines, but it
1898 is your code that must call these routines, so just declaring a symbol with
1899 <tt/.CONDES/ does nothing by itself.
1901 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1902 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1903 is implied by <tt/.CONDES/.
1905 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1906 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1907 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1908 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1909 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1910 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
1911 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
1913 After the type, an optional priority may be specified. Higher numeric values
1914 mean higher priority. If no priority is given, the default priority of 7 is
1915 used. Be careful when assigning priorities to your own module constructors
1916 so they won't interfere with the ones in the cc65 library.
1921 .condes ModuleInit, constructor
1922 .condes ModInit, 0, 16
1925 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1926 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1927 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
1928 name="Module constructors/destructors"> explaining the feature in more
1932 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1934 Export a symbol and mark it as a module constructor. This may be used
1935 together with the linker to build a table of constructor subroutines that
1936 are called by the startup code.
1938 Note: The linker has a feature to build a table of marked routines, but it
1939 is your code that must call these routines, so just declaring a symbol as
1940 constructor does nothing by itself.
1942 A constructor is always exported as an absolute (16 bit) symbol. You don't
1943 need to use an additional <tt/.export/ statement, this is implied by
1944 <tt/.constructor/. It may have an optional priority that is separated by a
1945 comma. Higher numeric values mean a higher priority. If no priority is
1946 given, the default priority of 7 is used. Be careful when assigning
1947 priorities to your own module constructors so they won't interfere with the
1948 ones in the cc65 library.
1953 .constructor ModuleInit
1954 .constructor ModInit, 16
1957 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1958 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1959 <ref id="condes" name="Module constructors/destructors"> explaining the
1960 feature in more detail.
1963 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1965 Switch to the DATA segment. The name of the DATA segment is always
1966 "DATA", so this is a shortcut for
1972 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1975 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1977 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1978 create word sized data in native 65XX format). Must be followed by a
1979 sequence of (word ranged) expressions.
1987 This will emit the bytes
1993 into the current segment in that order.
1996 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1998 Switch on or off debug info generation. The default is off (that is,
1999 the object file will not contain debug infos), but may be changed by the
2000 -g switch on the command line.
2001 The command must be followed by a '+' or '-' character to switch the
2002 option on or off respectively.
2007 .debuginfo + ; Generate debug info
2011 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2013 Start a define style macro definition. The command is followed by an
2014 identifier (the macro name) and optionally by a list of formal arguments
2016 See section <ref id="macros" name="Macros">.
2019 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2021 Builtin function. The function expects an identifier as argument in braces.
2022 The argument is evaluated, and the function yields "true" if the identifier
2023 is a symbol that is already defined somewhere in the source file up to the
2024 current position. Otherwise the function yields false. As an example, the
2025 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2032 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2034 Export a symbol and mark it as a module destructor. This may be used
2035 together with the linker to build a table of destructor subroutines that
2036 are called by the startup code.
2038 Note: The linker has a feature to build a table of marked routines, but it
2039 is your code that must call these routines, so just declaring a symbol as
2040 constructor does nothing by itself.
2042 A destructor is always exported as an absolute (16 bit) symbol. You don't
2043 need to use an additional <tt/.export/ statement, this is implied by
2044 <tt/.destructor/. It may have an optional priority that is separated by a
2045 comma. Higher numerical values mean a higher priority. If no priority is
2046 given, the default priority of 7 is used. Be careful when assigning
2047 priorities to your own module destructors so they won't interfere with the
2048 ones in the cc65 library.
2053 .destructor ModuleDone
2054 .destructor ModDone, 16
2057 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2058 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2059 section <ref id="condes" name="Module constructors/destructors"> explaining
2060 the feature in more detail.
2063 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2065 Define dword sized data (4 bytes) Must be followed by a sequence of
2071 .dword $12344512, $12FA489
2075 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2077 Conditional assembly: Reverse the current condition.
2080 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2082 Conditional assembly: Reverse current condition and test a new one.
2085 <sect1><tt>.END</tt><label id=".END"><p>
2087 Forced end of assembly. Assembly stops at this point, even if the command
2088 is read from an include file.
2091 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2093 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2096 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2098 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2099 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2102 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2104 End of macro definition (see section <ref id="macros" name="Macros">).
2107 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2109 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2112 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2114 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2117 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2119 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2122 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2124 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2125 command and the separate section named <ref id="structs" name=""Structs
2129 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2131 Start an enumeration. This directive is very similar to the C <tt/enum/
2132 keyword. If a name is given, a new scope is created for the enumeration,
2133 otherwise the enumeration members are placed in the enclosing scope.
2135 In the enumeration body, symbols are declared. The first symbol has a value
2136 of zero, and each following symbol will get the value of the preceding plus
2137 one. This behaviour may be overridden by an explicit assignment. Two symbols
2138 may have the same value.
2150 Above example will create a new scope named <tt/errorcodes/ with three
2151 symbols in it that get the values 0, 1 and 2 respectively. Another way
2152 to write this would have been:
2162 Please note that explicit scoping must be used to access the identifiers:
2165 .word errorcodes::no_error
2168 A more complex example:
2177 EWOULDBLOCK = EAGAIN
2181 In this example, the enumeration does not have a name, which means that the
2182 members will be visible in the enclosing scope and can be used in this scope
2183 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2184 The value for the following members is incremented by one, so <tt/EOK/ would
2185 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2186 override for the value using an already defined symbol.
2189 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2191 Force an assembly error. The assembler will output an error message
2192 preceded by "User error" and will <em/not/ produce an object file.
2194 This command may be used to check for initial conditions that must be
2195 set before assembling a source file.
2205 .error "Must define foo or bar!"
2209 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2210 id=".OUT" name=".OUT"></tt> directives.
2213 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2215 Abort a macro expansion immediately. This command is often useful in
2216 recursive macros. See separate section <ref id="macros" name="Macros">.
2219 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2221 Make symbols accessible from other modules. Must be followed by a comma
2222 separated list of symbols to export, with each one optionally followed by an
2223 address specification and (also optional) an assignment. Using an additional
2224 assignment in the export statement allows to define and export a symbol in
2225 one statement. The default is to export the symbol with the address size it
2226 actually has. The assembler will issue a warning, if the symbol is exported
2227 with an address size smaller than the actual address size.
2234 .export foobar: far = foo * bar
2235 .export baz := foobar, zap: far = baz - bar
2238 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2241 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2244 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2246 Make symbols accessible from other modules. Must be followed by a comma
2247 separated list of symbols to export. The exported symbols are explicitly
2248 marked as zero page symbols. An assignment may be included in the
2249 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2256 .exportzp baz := $02
2259 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2262 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2264 Define far (24 bit) address data. The command must be followed by a
2265 sequence of (not necessarily constant) expressions.
2270 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2273 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2276 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2278 This directive may be used to enable one or more compatibility features
2279 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2280 possible, it may be useful when porting sources written for other
2281 assemblers. There is no way to switch a feature off, once you have
2282 enabled it, so using
2288 will enable the feature until end of assembly is reached.
2290 The following features are available:
2294 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2296 Accept the at character (`@') as a valid character in identifiers. The
2297 at character is not allowed to start an identifier, even with this
2300 <tag><tt>c_comments</tt></tag>
2302 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2303 comment terminators. Note that C comments may not be nested. There's also a
2304 pitfall when using C like comments: All statements must be terminated by
2305 "end-of-line". Using C like comments, it is possible to hide the newline,
2306 which results in error messages. See the following non working example:
2309 lda #$00 /* This comment hides the newline
2313 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2315 Accept the dollar sign (`$') as a valid character in identifiers. The
2316 dollar character is not allowed to start an identifier, even with this
2319 <tag><tt>dollar_is_pc</tt></tag>
2321 The dollar sign may be used as an alias for the star (`*'), which
2322 gives the value of the current PC in expressions.
2323 Note: Assignment to the pseudo variable is not allowed.
2325 <tag><tt>labels_without_colons</tt></tag>
2327 Allow labels without a trailing colon. These labels are only accepted,
2328 if they start at the beginning of a line (no leading white space).
2330 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2332 Accept the dot (`.') as the first character of an identifier. This may be
2333 used for example to create macro names that start with a dot emulating
2334 control directives of other assemblers. Note however, that none of the
2335 reserved keywords built into the assembler, that starts with a dot, may be
2336 overridden. When using this feature, you may also get into trouble if
2337 later versions of the assembler define new keywords starting with a dot.
2339 <tag><tt>loose_char_term</tt></tag>
2341 Accept single quotes as well as double quotes as terminators for char
2344 <tag><tt>loose_string_term</tt></tag>
2346 Accept single quotes as well as double quotes as terminators for string
2349 <tag><tt>missing_char_term</tt></tag>
2351 Accept single quoted character constants where the terminating quote is
2356 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2357 loose_string_term/, since in this case the input would be ambiguous.
2359 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2361 This feature makes relocatable/absolute mode local to the current segment.
2362 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2363 effect will only enable absolute mode for the current segment. Dito for
2364 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2366 <tag><tt>pc_assignment</tt></tag>
2368 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2369 is enabled). Such an assignment is handled identical to the <tt><ref
2370 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2371 removing the lines with the assignments may also be an option when porting
2372 code written for older assemblers).
2374 <tag><tt>ubiquitous_idents</tt></tag>
2376 Allow the use of instructions names as names for macros and symbols. This
2377 makes it possible to "overload" instructions by defining a macro with the
2378 same name. This does also make it possible to introduce hard to find errors
2379 in your code, so be careful!
2383 It is also possible to specify features on the command line using the
2384 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2385 This is useful when translating sources written for older assemblers, when
2386 you don't want to change the source code.
2388 As an example, to translate sources written for Andre Fachats xa65
2389 assembler, the features
2392 labels_without_colons, pc_assignment, loose_char_term
2395 may be helpful. They do not make ca65 completely compatible, so you may not
2396 be able to translate the sources without changes, even when enabling these
2397 features. However, I have found several sources that translate without
2398 problems when enabling these features on the command line.
2401 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2403 Insert an option string into the object file. There are two forms of
2404 this command, one specifies the option by a keyword, the second
2405 specifies it as a number. Since usage of the second one needs knowledge
2406 of the internal encoding, its use is not recommended and I will only
2407 describe the first form here.
2409 The command is followed by one of the keywords
2417 a comma and a string. The option is written into the object file
2418 together with the string value. This is currently unidirectional and
2419 there is no way to actually use these options once they are in the
2425 .fileopt comment, "Code stolen from my brother"
2426 .fileopt compiler, "BASIC 2.0"
2427 .fopt author, "J. R. User"
2431 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2433 Import an absolute symbol from another module. The command is followed by a
2434 comma separated list of symbols to import. The command is similar to <tt>
2435 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2436 written to the generated object file, even if the symbol is never referenced
2437 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2438 references for unused symbols).
2443 .forceimport needthisone, needthistoo
2446 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2449 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2451 Declare symbols as global. Must be followed by a comma separated list of
2452 symbols to declare. Symbols from the list, that are defined somewhere in the
2453 source, are exported, all others are imported. Additional <tt><ref
2454 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2455 name=".EXPORT"></tt> commands for the same symbol are allowed.
2464 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2466 Declare symbols as global. Must be followed by a comma separated list of
2467 symbols to declare. Symbols from the list, that are defined somewhere in the
2468 source, are exported, all others are imported. Additional <tt><ref
2469 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2470 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2471 in the list are explicitly marked as zero page symbols.
2479 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2481 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2482 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2483 the operator '>' prepended to each expression in its list.
2488 .lobytes $1234, $2345, $3456, $4567
2489 .hibytes $fedc, $edcb, $dcba, $cba9
2492 which is equivalent to
2495 .byte $34, $45, $56, $67
2496 .byte $fe, $ed, $dc, $cb
2502 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2504 TableLookupLo: .lobytes MyTable
2505 TableLookupHi: .hibytes MyTable
2508 which is equivalent to
2511 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2512 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2515 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2516 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2517 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2520 <sect1><tt>.I16</tt><label id=".I16"><p>
2522 Valid only in 65816 mode. Switch the index registers to 16 bit.
2524 Note: This command will not emit any code, it will tell the assembler to
2525 create 16 bit operands for immediate operands.
2527 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2528 name=".SMART"></tt> commands.
2531 <sect1><tt>.I8</tt><label id=".I8"><p>
2533 Valid only in 65816 mode. Switch the index registers to 8 bit.
2535 Note: This command will not emit any code, it will tell the assembler to
2536 create 8 bit operands for immediate operands.
2538 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2539 name=".SMART"></tt> commands.
2542 <sect1><tt>.IF</tt><label id=".IF"><p>
2544 Conditional assembly: Evaluate an expression and switch assembler output
2545 on or off depending on the expression. The expression must be a constant
2546 expression, that is, all operands must be defined.
2548 A expression value of zero evaluates to FALSE, any other value evaluates
2552 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2554 Conditional assembly: Check if there are any remaining tokens in this line,
2555 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2556 condition is not true, further lines are not assembled until an <tt><ref
2557 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2558 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2560 This command is often used to check if a macro parameter was given. Since an
2561 empty macro parameter will evaluate to nothing, the condition will evaluate
2562 to FALSE if an empty parameter was given.
2576 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2579 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2581 Conditional assembly: Evaluate an expression and switch assembler output
2582 on or off depending on the constness of the expression.
2584 A const expression evaluates to to TRUE, a non const expression (one
2585 containing an imported or currently undefined symbol) evaluates to
2588 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2591 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2593 Conditional assembly: Check if a symbol is defined. Must be followed by
2594 a symbol name. The condition is true if the the given symbol is already
2595 defined, and false otherwise.
2597 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2600 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2602 Conditional assembly: Check if there are any remaining tokens in this line,
2603 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2604 condition is not true, further lines are not assembled until an <tt><ref
2605 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2606 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2608 This command is often used to check if a macro parameter was given.
2609 Since an empty macro parameter will evaluate to nothing, the condition
2610 will evaluate to FALSE if an empty parameter was given.
2623 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2626 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2628 Conditional assembly: Check if a symbol is defined. Must be followed by
2629 a symbol name. The condition is true if the the given symbol is not
2630 defined, and false otherwise.
2632 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2635 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2637 Conditional assembly: Check if a symbol is referenced. Must be followed
2638 by a symbol name. The condition is true if if the the given symbol was
2639 not referenced before, and false otherwise.
2641 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2644 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2646 Conditional assembly: Check if the assembler is currently in 6502 mode
2647 (see <tt><ref id=".P02" name=".P02"></tt> command).
2650 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2652 Conditional assembly: Check if the assembler is currently in 65816 mode
2653 (see <tt><ref id=".P816" name=".P816"></tt> command).
2656 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2658 Conditional assembly: Check if the assembler is currently in 65C02 mode
2659 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2662 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2664 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2665 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2668 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2670 Conditional assembly: Check if a symbol is referenced. Must be followed
2671 by a symbol name. The condition is true if if the the given symbol was
2672 referenced before, and false otherwise.
2674 This command may be used to build subroutine libraries in include files
2675 (you may use separate object modules for this purpose too).
2680 .ifref ToHex ; If someone used this subroutine
2681 ToHex: tay ; Define subroutine
2687 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2690 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2692 Import a symbol from another module. The command is followed by a comma
2693 separated list of symbols to import, with each one optionally followed by
2694 an address specification.
2700 .import bar: zeropage
2703 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2706 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2708 Import a symbol from another module. The command is followed by a comma
2709 separated list of symbols to import. The symbols are explicitly imported
2710 as zero page symbols (that is, symbols with values in byte range).
2718 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2721 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2723 Include a file as binary data. The command expects a string argument
2724 that is the name of a file to include literally in the current segment.
2725 In addition to that, a start offset and a size value may be specified,
2726 separated by commas. If no size is specified, all of the file from the
2727 start offset to end-of-file is used. If no start position is specified
2728 either, zero is assumed (which means that the whole file is inserted).
2733 ; Include whole file
2734 .incbin "sprites.dat"
2736 ; Include file starting at offset 256
2737 .incbin "music.dat", $100
2739 ; Read 100 bytes starting at offset 200
2740 .incbin "graphics.dat", 200, 100
2744 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2746 Include another file. Include files may be nested up to a depth of 16.
2755 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
2757 Export a symbol and mark it as an interruptor. This may be used together
2758 with the linker to build a table of interruptor subroutines that are called
2761 Note: The linker has a feature to build a table of marked routines, but it
2762 is your code that must call these routines, so just declaring a symbol as
2763 interruptor does nothing by itself.
2765 An interruptor is always exported as an absolute (16 bit) symbol. You don't
2766 need to use an additional <tt/.export/ statement, this is implied by
2767 <tt/.interruptor/. It may have an optional priority that is separated by a
2768 comma. Higher numeric values mean a higher priority. If no priority is
2769 given, the default priority of 7 is used. Be careful when assigning
2770 priorities to your own module constructors so they won't interfere with the
2771 ones in the cc65 library.
2776 .interruptor IrqHandler
2777 .interruptor Handler, 16
2780 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
2781 section <ref id="condes" name="Module constructors/destructors"> explaining
2782 the feature in more detail.
2785 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2787 Switch on or off line continuations using the backslash character
2788 before a newline. The option is off by default.
2789 Note: Line continuations do not work in a comment. A backslash at the
2790 end of a comment is treated as part of the comment and does not trigger
2792 The command must be followed by a '+' or '-' character to switch the
2793 option on or off respectively.
2798 .linecont + ; Allow line continuations
2801 #$20 ; This is legal now
2805 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2807 Enable output to the listing. The command must be followed by a boolean
2808 switch ("on", "off", "+" or "-") and will enable or disable listing
2810 The option has no effect if the listing is not enabled by the command line
2811 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2812 to the listing file, if the counter is greater than zero, and suppressed if
2813 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2819 .list on ; Enable listing output
2823 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2825 Set, how many bytes are shown in the listing for one source line. The
2826 default is 12, so the listing will show only the first 12 bytes for any
2827 source line that generates more than 12 bytes of code or data.
2828 The directive needs an argument, which is either "unlimited", or an
2829 integer constant in the range 4..255.
2834 .listbytes unlimited ; List all bytes
2835 .listbytes 12 ; List the first 12 bytes
2836 .incbin "data.bin" ; Include large binary file
2840 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
2842 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
2843 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2844 the operator '<' prepended to each expression in its list.
2849 .lobytes $1234, $2345, $3456, $4567
2850 .hibytes $fedc, $edcb, $dcba, $cba9
2853 which is equivalent to
2856 .byte $34, $45, $56, $67
2857 .byte $fe, $ed, $dc, $cb
2863 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2865 TableLookupLo: .lobytes MyTable
2866 TableLookupHi: .hibytes MyTable
2869 which is equivalent to
2872 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2873 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2876 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2877 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2878 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2881 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2883 This command may only be used inside a macro definition. It declares a
2884 list of identifiers as local to the macro expansion.
2886 A problem when using macros are labels: Since they don't change their name,
2887 you get a "duplicate symbol" error if the macro is expanded the second time.
2888 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2889 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2892 Some other assemblers start a new lexical block inside a macro expansion.
2893 This has some drawbacks however, since that will not allow <em/any/ symbol
2894 to be visible outside a macro, a feature that is sometimes useful. The
2895 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2896 to address the problem.
2898 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2902 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2904 Defines the character that start "cheap" local labels. You may use one
2905 of '@' and '?' as start character. The default is '@'.
2907 Cheap local labels are labels that are visible only between two non
2908 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2909 using explicit lexical nesting.
2916 Clear: lda #$00 ; Global label
2917 ?Loop: sta Mem,y ; Local label
2921 Sub: ... ; New global label
2922 bne ?Loop ; ERROR: Unknown identifier!
2926 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2928 Insert a predefined macro package. The command is followed by an
2929 identifier specifying the macro package to insert. Available macro
2933 atari Defines the scrcode macro.
2934 cbm Defines the scrcode macro.
2935 cpu Defines constants for the .CPU variable.
2936 generic Defines generic macros like add and sub.
2937 longbranch Defines conditional long jump macros.
2940 Including a macro package twice, or including a macro package that
2941 redefines already existing macros will lead to an error.
2946 .macpack longbranch ; Include macro package
2948 cmp #$20 ; Set condition codes
2949 jne Label ; Jump long on condition
2952 Macro packages are explained in more detail in section <ref
2953 id="macropackages" name="Macro packages">.
2956 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2958 Start a classic macro definition. The command is followed by an identifier
2959 (the macro name) and optionally by a comma separated list of identifiers
2960 that are macro parameters.
2962 See section <ref id="macros" name="Macros">.
2965 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2967 Start a section of absolute code. The command is followed by a constant
2968 expression that gives the new PC counter location for which the code is
2969 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2972 By default, absolute/relocatable mode is global (valid even when switching
2973 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
2974 it can be made segment local.
2976 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
2977 code at a specific address is the job of the linker, not the assembler, so
2978 there is usually no reason to assemble code to a specific address.
2983 .org $7FF ; Emit code starting at $7FF
2987 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2989 Output a string to the console without producing an error. This command
2990 is similar to <tt/.ERROR/, however, it does not force an assembler error
2991 that prevents the creation of an object file.
2996 .out "This code was written by the codebuster(tm)"
2999 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
3000 id=".ERROR" name=".ERROR"></tt> directives.
3003 <sect1><tt>.P02</tt><label id=".P02"><p>
3005 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3006 instructions. This is the default if not overridden by the
3007 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3009 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3010 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3013 <sect1><tt>.P816</tt><label id=".P816"><p>
3015 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3016 6502 instruction sets.
3018 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3019 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3022 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3024 Set the page length for the listing. Must be followed by an integer
3025 constant. The value may be "unlimited", or in the range 32 to 127. The
3026 statement has no effect if no listing is generated. The default value is -1
3027 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3028 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3029 after assembly is complete, you cannot use multiple line lengths with one
3030 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3035 .pagelength 66 ; Use 66 lines per listing page
3037 .pagelength unlimited ; Unlimited page length
3041 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3043 Enable the 65C02 instructions set. This instruction set includes all
3044 6502 and 65SC02 instructions.
3046 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3047 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3050 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3052 Pop the last pushed segment from the stack, and set it.
3054 This command will switch back to the segment that was last pushed onto the
3055 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3056 command, and remove this entry from the stack.
3058 The assembler will print an error message if the segment stack is empty
3059 when this command is issued.
3061 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3064 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3066 Start a nested lexical level with the given name and adds a symbol with this
3067 name to the enclosing scope. All new symbols from now on are in the local
3068 lexical level and are accessible from outside only via <ref id="scopesyntax"
3069 name="explicit scope specification">. Symbols defined outside this local
3070 level may be accessed as long as their names are not used for new symbols
3071 inside the level. Symbols names in other lexical levels do not clash, so you
3072 may use the same names for identifiers. The lexical level ends when the
3073 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3074 may be nested up to a depth of 16 (this is an artificial limit to protect
3075 against errors in the source).
3077 Note: Macro names are always in the global level and in a separate name
3078 space. There is no special reason for this, it's just that I've never
3079 had any need for local macro definitions.
3084 .proc Clear ; Define Clear subroutine, start new level
3086 L1: sta Mem,y ; L1 is local and does not cause a
3087 ; duplicate symbol error if used in other
3090 bne L1 ; Reference local symbol
3092 .endproc ; Leave lexical level
3095 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3099 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3101 Enable the 65SC02 instructions set. This instruction set includes all
3104 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3105 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3108 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3110 Push the currently active segment onto a stack. The entries on the stack
3111 include the name of the segment and the segment type. The stack has a size
3114 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3115 to switch to another segment and to restore the old segment later, without
3116 even knowing the name and type of the current segment.
3118 The assembler will print an error message if the segment stack is already
3119 full, when this command is issued.
3121 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3124 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3126 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3127 name=".ORG"></tt> command.
3130 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3132 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3133 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3134 a constant expression that tells how many times the commands in the body
3135 should get repeated. Optionally, a comma and an identifier may be specified.
3136 If this identifier is found in the body of the repeat statement, it is
3137 replaced by the current repeat count (starting with zero for the first time
3138 the body is repeated).
3140 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3141 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3142 level will be used, not the one from the outer level.
3146 The following macro will emit a string that is "encrypted" in that all
3147 characters of the string are XORed by the value $55.
3151 .repeat .strlen(Arg), I
3152 .byte .strat(Arg, I) ^ $55
3157 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3160 <sect1><tt>.RES</tt><label id=".RES"><p>
3162 Reserve storage. The command is followed by one or two constant
3163 expressions. The first one is mandatory and defines, how many bytes of
3164 storage should be defined. The second, optional expression must by a
3165 constant byte value that will be used as value of the data. If there
3166 is no fill value given, the linker will use the value defined in the
3167 linker configuration file (default: zero).
3172 ; Reserve 12 bytes of memory with value $AA
3177 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3179 Switch to the RODATA segment. The name of the RODATA segment is always
3180 "RODATA", so this is a shortcut for
3186 The RODATA segment is a segment that is used by the compiler for
3187 readonly data like string constants.
3189 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3192 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3194 Start a nested lexical level with the given name. All new symbols from now
3195 on are in the local lexical level and are accessible from outside only via
3196 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3197 outside this local level may be accessed as long as their names are not used
3198 for new symbols inside the level. Symbols names in other lexical levels do
3199 not clash, so you may use the same names for identifiers. The lexical level
3200 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3201 read. Lexical levels may be nested up to a depth of 16 (this is an
3202 artificial limit to protect against errors in the source).
3204 Note: Macro names are always in the global level and in a separate name
3205 space. There is no special reason for this, it's just that I've never
3206 had any need for local macro definitions.
3211 .scope Error ; Start new scope named Error
3213 File = 1 ; File error
3214 Parse = 2 ; Parse error
3215 .endscope ; Close lexical level
3218 lda #Error::File ; Use symbol from scope Error
3221 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3225 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3227 Switch to another segment. Code and data is always emitted into a
3228 segment, that is, a named section of data. The default segment is
3229 "CODE". There may be up to 254 different segments per object file
3230 (and up to 65534 per executable). There are shortcut commands for
3231 the most common segments ("CODE", "DATA" and "BSS").
3233 The command is followed by a string containing the segment name (there are
3234 some constraints for the name - as a rule of thumb use only those segment
3235 names that would also be valid identifiers). There may also be an optional
3236 address size separated by a colon. See the section covering <tt/<ref
3237 id="address-sizes" name="address sizes">/ for more information.
3239 The default address size for a segment depends on the memory model specified
3240 on the command line. The default is "absolute", which means that you don't
3241 have to use an address size modifier in most cases.
3243 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3244 That is, the segment will reside somewhere in core memory outside the zero
3245 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3246 page and direct (short) addressing is possible for data in this segment.
3248 Beware: Only labels in a segment with the zeropage attribute are marked
3249 as reachable by short addressing. The `*' (PC counter) operator will
3250 work as in other segments and will create absolute variable values.
3252 Please note that a segment cannot have two different address sizes. A
3253 segment specified as zeropage cannot be declared as being absolute later.
3258 .segment "ROM2" ; Switch to ROM2 segment
3259 .segment "ZP2": zeropage ; New direct segment
3260 .segment "ZP2" ; Ok, will use last attribute
3261 .segment "ZP2": absolute ; Error, redecl mismatch
3264 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3265 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3266 id=".RODATA" name=".RODATA"></tt>
3269 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3271 Switch the CPU instruction set. The command is followed by a string that
3272 specifies the CPU. Possible values are those that can also be supplied to
3273 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3274 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3275 note that support for the sunplus CPU is not available in the freeware
3276 version, because the instruction set of the sunplus CPU is "proprietary
3279 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3280 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3281 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3282 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3283 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3284 <tt><ref id=".P02" name=".P02"></tt>,
3285 <tt><ref id=".P816" name=".P816"></tt>,
3286 <tt><ref id=".PC02" name=".PC02"></tt>,
3287 <tt><ref id=".PSC02" name=".PSC02"></tt>
3290 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3292 Switch on or off smart mode. The command must be followed by a '+' or '-'
3293 character to switch the option on or off respectively. The default is off
3294 (that is, the assembler doesn't try to be smart), but this default may be
3295 changed by the -s switch on the command line.
3297 In smart mode the assembler will do the following:
3300 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3301 and update the operand sizes accordingly. If the operand of such an
3302 instruction cannot be evaluated by the assembler (for example, because
3303 the operand is an imported symbol), a warning is issued. Beware: Since
3304 the assembler cannot trace the execution flow this may lead to false
3305 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3306 instructions to tell the assembler about the current settings.
3307 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3308 used within a procedure declared as <tt/far/, or if the procedure has
3309 no explicit address specification, but it is <tt/far/ because of the
3317 .smart - ; Stop being smart
3320 See: <tt><ref id=".A16" name=".A16"></tt>,
3321 <tt><ref id=".A8" name=".A8"></tt>,
3322 <tt><ref id=".I16" name=".I16"></tt>,
3323 <tt><ref id=".I8" name=".I8"></tt>
3326 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3328 Starts a struct definition. Structs are covered in a separate section named
3329 <ref id="structs" name=""Structs and unions"">.
3331 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3334 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3336 Enable the SunPlus instructions set. This command will not work in the
3337 freeware version of the assembler, because the instruction set is
3338 "proprietary and confidential".
3340 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3341 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3342 <tt><ref id=".P816" name=".P816"></tt>
3345 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3347 Allocate space for a struct or union.
3358 .tag Point ; Allocate 4 bytes
3362 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3364 Force an assembly warning. The assembler will output a warning message
3365 preceded by "User warning". This warning will always be output, even if
3366 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3367 command line option.
3369 This command may be used to output possible problems when assembling
3378 .warning "Forward jump in jne, cannot optimize!"
3388 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
3389 name=".OUT"></tt> directives.
3392 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3394 Define word sized data. Must be followed by a sequence of (word ranged,
3395 but not necessarily constant) expressions.
3400 .word $0D00, $AF13, _Clear
3404 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3406 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3407 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3411 .segment "ZEROPAGE", zeropage
3414 Because of the "zeropage" attribute, labels declared in this segment are
3415 addressed using direct addressing mode if possible. You <em/must/ instruct
3416 the linker to place this segment somewhere in the address range 0..$FF
3417 otherwise you will get errors.
3419 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3423 <sect>Macros<label id="macros"><p>
3426 <sect1>Introduction<p>
3428 Macros may be thought of as "parametrized super instructions". Macros are
3429 sequences of tokens that have a name. If that name is used in the source
3430 file, the macro is "expanded", that is, it is replaced by the tokens that
3431 were specified when the macro was defined.
3434 <sect1>Macros without parameters<p>
3436 In it's simplest form, a macro does not have parameters. Here's an
3440 .macro asr ; Arithmetic shift right
3441 cmp #$80 ; Put bit 7 into carry
3442 ror ; Rotate right with carry
3446 The macro above consists of two real instructions, that are inserted into
3447 the code, whenever the macro is expanded. Macro expansion is simply done
3448 by using the name, like this:
3457 <sect1>Parametrized macros<p>
3459 When using macro parameters, macros can be even more useful:
3473 When calling the macro, you may give a parameter, and each occurrence of
3474 the name "addr" in the macro definition will be replaced by the given
3493 A macro may have more than one parameter, in this case, the parameters
3494 are separated by commas. You are free to give less parameters than the
3495 macro actually takes in the definition. You may also leave intermediate
3496 parameters empty. Empty parameters are replaced by empty space (that is,
3497 they are removed when the macro is expanded). If you have a look at our
3498 macro definition above, you will see, that replacing the "addr" parameter
3499 by nothing will lead to wrong code in most lines. To help you, writing
3500 macros with a variable parameter list, there are some control commands:
3502 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3503 returns true, if there are any tokens on the remainder of the line. Since
3504 empty parameters are replaced by nothing, this may be used to test if a given
3505 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3508 Look at this example:
3511 .macro ldaxy a, x, y
3524 This macro may be called as follows:
3527 ldaxy 1, 2, 3 ; Load all three registers
3529 ldaxy 1, , 3 ; Load only a and y
3531 ldaxy , , 3 ; Load y only
3534 There's another helper command for determining, which macro parameters are
3535 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3536 replaced by the parameter count given, <em/including/ intermediate empty macro
3540 ldaxy 1 ; .PARAMCOUNT = 1
3541 ldaxy 1,,3 ; .PARAMCOUNT = 3
3542 ldaxy 1,2 ; .PARAMCOUNT = 2
3543 ldaxy 1, ; .PARAMCOUNT = 2
3544 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3547 Macro parameters may optionally be enclosed into curly braces. This allows the
3548 inclusion of tokens that would otherwise terminate the parameter (the comma in
3549 case of a macro parameter).
3552 .macro foo arg1, arg2
3556 foo ($00,x) ; Two parameters passed
3557 foo {($00,x)} ; One parameter passed
3560 In the first case, the macro is called with two parameters: '<tt/($00/'
3561 and 'x)'. The comma is not passed to the macro, since it is part of the
3562 calling sequence, not the parameters.
3564 In the second case, '($00,x)' is passed to the macro, this time
3565 including the comma.
3568 <sect1>Detecting parameter types<p>
3570 Sometimes it is nice to write a macro that acts differently depending on the
3571 type of the argument supplied. An example would be a macro that loads a 16 bit
3572 value from either an immediate operand, or from memory. The <tt/<ref
3573 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3574 functions will allow you to do exactly this:
3578 .if (.match (.left (1, {arg}), #))
3580 lda #<(.right (.tcount ({arg})-1, {arg}))
3581 ldx #>(.right (.tcount ({arg})-1, {arg}))
3583 ; assume absolute or zero page
3590 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3591 check if its argument begins with a hash mark. If so, two immediate loads are
3592 emitted, Otherwise a load from an absolute zero page memory location is
3593 assumed. Please note how the curly braces are used to enclose parameters to
3594 pseudo functions handling token lists. This is necessary, because the token
3595 lists may include commas or parens, which would be treated by the assembler
3598 The macro can be used as
3603 ldax #$1234 ; X=$12, A=$34
3605 ldax foo ; X=$56, A=$78
3609 <sect1>Recursive macros<p>
3611 Macros may be used recursively:
3614 .macro push r1, r2, r3
3623 There's also a special macro to help writing recursive macros: <tt><ref
3624 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3628 .macro push r1, r2, r3, r4, r5, r6, r7
3630 ; First parameter is empty
3636 push r2, r3, r4, r5, r6, r7
3640 When expanding this macro, the expansion will push all given parameters
3641 until an empty one is encountered. The macro may be called like this:
3644 push $20, $21, $32 ; Push 3 ZP locations
3645 push $21 ; Push one ZP location
3649 <sect1>Local symbols inside macros<p>
3651 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3652 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3653 Have a look at the inc16 macro above. Here is it again:
3667 If you have a closer look at the code, you will notice, that it could be
3668 written more efficiently, like this:
3679 But imagine what happens, if you use this macro twice? Since the label
3680 "Skip" has the same name both times, you get a "duplicate symbol" error.
3681 Without a way to circumvent this problem, macros are not as useful, as
3682 they could be. One solution is, to start a new lexical block inside the
3696 Now the label is local to the block and not visible outside. However,
3697 sometimes you want a label inside the macro to be visible outside. To make
3698 that possible, there's a new command that's only usable inside a macro
3699 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3700 or more symbols as local to the macro expansion. The names of local variables
3701 are replaced by a unique name in each separate macro expansion. So we could
3702 also solve the problem above by using <tt/.LOCAL/:
3706 .local Skip ; Make Skip a local symbol
3713 Skip: ; Not visible outside
3718 <sect1>C style macros<p>
3720 Starting with version 2.5 of the assembler, there is a second macro type
3721 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3722 similar to the classic macro type described above, but behaviour is sometimes
3727 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3728 span more than a line. You may use line continuation (see <tt><ref
3729 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3730 more than one line for increased readability, but the macro itself
3731 may not contain an end-of-line token.
3733 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3734 the name space with classic macros, but they are detected and replaced
3735 at the scanner level. While classic macros may be used in every place,
3736 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3737 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3738 they are more versatile in some situations.
3740 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3741 parameters. While classic macros may have empty parameters, this is
3742 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3743 For this macro type, the number of actual parameters must match
3744 exactly the number of formal parameters.
3746 To make this possible, formal parameters are enclosed in braces when
3747 defining the macro. If there are no parameters, the empty braces may
3750 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3751 contain end-of-line tokens, there are things that cannot be done. They
3752 may not contain several processor instructions for example. So, while
3753 some things may be done with both macro types, each type has special
3754 usages. The types complement each other.
3758 Let's look at a few examples to make the advantages and disadvantages
3761 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3762 following <tt/.DEFINE/:
3767 foo EQU $1234 ; This is accepted now
3770 You may use the directive to define string constants used elsewhere:
3773 ; Define the version number
3774 .define VERSION "12.3a"
3780 Macros with parameters may also be useful:
3783 .define DEBUG(message) .out message
3785 DEBUG "Assembling include file #3"
3788 Note that, while formal parameters have to be placed in braces, this is
3789 not true for the actual parameters. Beware: Since the assembler cannot
3790 detect the end of one parameter, only the first token is used. If you
3791 don't like that, use classic macros instead:
3799 (This is an example where a problem can be solved with both macro types).
3802 <sect1>Characters in macros<p>
3804 When using the <ref id="option-t" name="-t"> option, characters are translated
3805 into the target character set of the specific machine. However, this happens
3806 as late as possible. This means that strings are translated if they are part
3807 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3808 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3809 used as part of an expression.
3811 This behaviour is very intuitive outside of macros but may be confusing when
3812 doing more complex macros. If you compare characters against numeric values,
3813 be sure to take the translation into account.
3818 <sect>Macro packages<label id="macropackages"><p>
3820 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3821 macro packages may be included with just one command. Available macro packages
3825 <sect1><tt>.MACPACK generic</tt><p>
3827 This macro package defines macros that are useful in almost any program.
3828 Currently, two macros are defined:
3843 <sect1><tt>.MACPACK longbranch</tt><p>
3845 This macro package defines long conditional jumps. They are named like the
3846 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3847 definition for the "<tt/jeq/" macro, the other macros are built using the same
3852 .if .def(Target) .and ((*+2)-(Target) <= 127)
3861 All macros expand to a short branch, if the label is already defined (back
3862 jump) and is reachable with a short jump. Otherwise the macro expands to a
3863 conditional branch with the branch condition inverted, followed by an absolute
3864 jump to the actual branch target.
3866 The package defines the following macros:
3869 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3874 <sect1><tt>.MACPACK cbm</tt><p>
3876 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3877 string as argument and places this string into memory translated into screen
3881 <sect1><tt>.MACPACK cpu</tt><p>
3883 This macro package does not define any macros but constants used to examine
3884 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3885 each supported CPU a constant similar to
3897 is defined. These constants may be used to determine the exact type of the
3898 currently enabled CPU. In addition to that, for each CPU instruction set,
3899 another constant is defined:
3911 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3912 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3913 currently enabled CPU supports a specific instruction set. For example the
3914 65C02 supports all instructions of the 65SC02 CPU, so it has the
3915 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3919 .if (.cpu .bitand CPU_ISET_65SC02)
3927 it is possible to determine if the
3933 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3934 CPUs (the latter two are upwards compatible to the 65SC02).
3938 <sect>Predefined constants<label id="predefined-constants"><p>
3940 For better orthogonality, the assembler defines similar symbols as the
3941 compiler, depending on the target system selected:
3944 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
3945 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
3946 <item><tt/__ATARI__/ - Target system is <tt/atari/
3947 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
3948 <item><tt/__BBC__/ - Target system is <tt/bbc/
3949 <item><tt/__C128__/ - Target system is <tt/c128/
3950 <item><tt/__C16__/ - Target system is <tt/c16/
3951 <item><tt/__C64__/ - Target system is <tt/c64/
3952 <item><tt/__CBM__/ - Target is a Commodore system
3953 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
3954 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
3955 <item><tt/__GEOS__/ - Target system is <tt/geos/
3956 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
3957 <item><tt/__NES__/ - Target system is <tt/nes/
3958 <item><tt/__PET__/ - Target system is <tt/pet/
3959 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
3960 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
3961 <item><tt/__VIC20__/ - Target system is <tt/vic20/
3965 <sect>Structs and unions<label id="structs"><p>
3967 <sect1>Structs and unions Overview<p>
3969 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3970 are to some degree comparable to their C counterparts. Both have a list of
3971 members. Each member allocates storage and may optionally have a name, which,
3972 in case of a struct, is the offset from the beginning and, in case of a union,
3976 <sect1>Declaration<p>
3978 Here is an example for a very simple struct with two members and a total size
3988 A union shares the total space between all its members, its size is the same
3989 as that of the largest member.
3991 A struct or union must not necessarily have a name. If it is anonymous, no
3992 local scope is opened, the identifiers used to name the members are placed
3993 into the current scope instead.
3995 A struct may contain unnamed members and definitions of local structs. The
3996 storage allocators may contain a multiplier, as in the example below:
4001 .word 2 ; Allocate two words
4008 <sect1>The <tt/.TAG/ keyword<p>
4010 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4011 for an already defined struct or unions within another struct:
4025 Space for a struct or union may be allocated using the <ref id=".TAG"
4026 name=".TAG"> directive.
4032 Currently, members are just offsets from the start of the struct or union. To
4033 access a field of a struct, the member offset has to be added to the address
4034 of the struct itself:
4037 lda C+Circle::Radius ; Load circle radius into A
4040 This may change in a future version of the assembler.
4043 <sect1>Limitations<p>
4045 Structs and unions are currently implemented as nested symbol tables (in fact,
4046 they were a by-product of the improved scoping rules). Currently, the
4047 assembler has no idea of types. This means that the <ref id=".TAG"
4048 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4049 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4050 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4051 this structure accessible by using the '::' operator.
4055 <sect>Module constructors/destructors<label id="condes"><p>
4057 <em>Note:</em> This section applies mostly to C programs, so the explanation
4058 below uses examples from the C libraries. However, the feature may also be
4059 useful for assembler programs.
4062 <sect1>Module constructors/destructors Overview<p>
4064 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4065 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4066 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
4067 special way. The linker is able to generate tables with all functions of a
4068 specific type. Such a table will <em>only</em> include symbols from object
4069 files that are linked into a specific executable. This may be used to add
4070 initialization and cleanup code for library modules, or a table of interrupt
4073 The C heap functions are an example where module initialization code is used.
4074 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4075 variables that contain the start and the end of the heap, pointers to the free
4076 list and so on. Since the end of the heap depends on the size and start of the
4077 stack, it must be initialized at runtime. However, initializing these
4078 variables for programs that do not use the heap are a waste of time and
4081 So the central module defines a function that contains initialization code and
4082 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4083 this module is added to an executable by the linker, the initialization
4084 function will be placed into the table of constructors by the linker. The C
4085 startup code will call all constructors before <tt/main/ and all destructors
4086 after <tt/main/, so without any further work, the heap initialization code is
4087 called once the module is linked in.
4089 While it would be possible to add explicit calls to initialization functions
4090 in the startup code, the new approach has several advantages:
4094 If a module is not included, the initialization code is not linked in and not
4095 called. So you don't pay for things you don't need.
4098 Adding another library that needs initialization does not mean that the
4099 startup code has to be changed. Before we had module constructors and
4100 destructors, the startup code for all systems had to be adjusted to call the
4101 new initialization code.
4104 The feature saves memory: Each additional initialization function needs just
4105 two bytes in the table (a pointer to the function).
4110 <sect1>Calling order<p>
4112 The symbols are sorted in increasing priority order by the linker when using
4113 one of the builtin linker configurations, so the functions with lower
4114 priorities come first and are followed by those with higher priorities. The C
4115 library runtime subroutine that walks over the function tables calls the
4116 functions starting from the top of the table - which means that functions with
4117 a high priority are called first.
4119 So when using the C runtime, functions are called with high priority functions
4120 first, followed by low priority functions.
4125 When using these special symbols, please take care of the following:
4130 The linker will only generate function tables, it will not generate code to
4131 call these functions. If you're using the feature in some other than the
4132 existing C environments, you have to write code to call all functions in a
4133 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4134 in the C runtime for an example on how to do this.
4137 The linker will only add addresses of functions that are in modules linked to
4138 the executable. This means that you have to be careful where to place the
4139 condes functions. If initialization or an irq handler is needed for a group of
4140 functions, be sure to place the function into a module that is linked in
4141 regardless of which function is called by the user.
4144 The linker will generate the tables only when requested to do so by the
4145 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4146 be requested separately.
4149 Constructors and destructors may have priorities. These priorities determine
4150 the order of the functions in the table. If your initialization or cleanup code
4151 does depend on other initialization or cleanup code, you have to choose the
4152 priority for the functions accordingly.
4155 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4156 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4157 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4158 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4159 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4160 (interruptor). The linker generates a separate table for each type on request.
4165 <sect>Porting sources from other assemblers<p>
4167 Sometimes it is necessary to port code written for older assemblers to ca65.
4168 In some cases, this can be done without any changes to the source code by
4169 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4170 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4173 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4174 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4175 done by the linker. Most other assemblers generate absolute code, placement is
4176 done within the assembler and there is no external linker.
4178 In general it is not a good idea to write new code using the emulation
4179 features of the assembler, but there may be situations where even this rule is
4184 You need to use some of the ca65 emulation features to simulate the behaviour
4185 of such simple assemblers.
4188 <item>Prepare your sourcecode like this:
4191 ; if you want TASS style labels without colons
4192 .feature labels_without_colons
4194 ; if you want TASS style character constants
4195 ; ("a" instead of the default 'a')
4196 .feature loose_char_term
4198 .word *+2 ; the cbm load address
4203 notice that the two emulation features are mostly useful for porting
4204 sources originally written in/for TASS, they are not needed for the
4205 actual "simple assembler operation" and are not recommended if you are
4206 writing new code from scratch.
4208 <item>Replace all program counter assignments (which are not possible in ca65
4209 by default, and the respective emulation feature works different from what
4210 you'd expect) by another way to skip to memory locations, for example the
4211 <tt><ref id=".RES" name=".RES"></tt> directive.
4215 .res $2000-* ; reserve memory up to $2000
4218 Please note that other than the original TASS, ca65 can never move the program
4219 counter backwards - think of it as if you are assembling to disk with TASS.
4221 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4222 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4223 of <tt/.goto/, everything involving loops must be replaced by
4224 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4226 <item>To assemble code to a different address than it is executed at, use the
4227 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4228 <tt/.offs/-constructs.
4235 .reloc ; back to normal
4238 <item>Then assemble like this:
4241 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4244 Note that you need to use the actual start address minus two, since two bytes
4245 are used for the cbm load address.
4250 <sect>Bugs/Feedback<p>
4252 If you have problems using the assembler, if you find any bugs, or if
4253 you're doing something interesting with the assembler, I would be glad to
4254 hear from you. Feel free to contact me by email
4255 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4261 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4262 Bassewitz. For usage of the binaries and/or sources the following
4263 conditions do apply:
4265 This software is provided 'as-is', without any expressed or implied
4266 warranty. In no event will the authors be held liable for any damages
4267 arising from the use of this software.
4269 Permission is granted to anyone to use this software for any purpose,
4270 including commercial applications, and to alter it and redistribute it
4271 freely, subject to the following restrictions:
4274 <item> The origin of this software must not be misrepresented; you must not
4275 claim that you wrote the original software. If you use this software
4276 in a product, an acknowledgment in the product documentation would be
4277 appreciated but is not required.
4278 <item> Altered source versions must be plainly marked as such, and must not
4279 be misrepresented as being the original software.
4280 <item> This notice may not be removed or altered from any source