1 <!doctype linuxdoc system>
4 <title>ca65 Users Guide
5 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
6 <date>2000-07-19, 2000-11-29, 2001-10-02, 2005-09-08
9 ca65 is a powerful macro assembler for the 6502, 65C02 and 65816 CPUs. It is
10 used as a companion assembler for the cc65 crosscompiler, but it may also be
11 used as a standalone product.
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
22 compiler, originally developed by John R. Dunning. I had some problems with
23 ra65 and the copyright does not permit some things which I wanted to be
24 possible, so I decided to write a completely new assembler/linker/archiver
25 suite for the cc65 compiler. ca65 is part of this suite.
27 Some parts of the assembler (code generation and some routines for symbol
28 table handling) are taken from an older crossassembler named a816 written
29 by me a long time ago.
32 <sect1>Design criteria<p>
34 Here's a list of the design criteria, that I considered important for the
39 <item> The assembler must support macros. Macros are not essential, but they
40 make some things easier, especially when you use the assembler in the
41 backend of a compiler.
42 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
43 thinking about a 65816 backend for the C compiler, and even my old
44 a816 assembler had support for these CPUs, so this wasn't really a
46 <item> The assembler must produce relocatable code. This is necessary for the
47 compiler support, and it is more convenient.
48 <item> Conditional assembly must be supported. This is a must for bigger
49 projects written in assembler (like Elite128).
50 <item> The assembler must support segments, and it must support more than
51 three segments (this is the count, most other assemblers support).
52 Having more than one code segments helps developing code for systems
53 with a divided ROM area (like the C64).
54 <item> The linker must be able to resolve arbitrary expressions. It should
55 be able to get things like
62 <item> True lexical nesting for symbols. This is very convenient for larger
64 <item> "Cheap" local symbols without lexical nesting for those quick, late
66 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
67 introduced the concept into the object file format use by the new cc65
69 <item> The assembler will be a one pass assembler. There was no real need for
70 this decision, but I've written several multipass assemblers, and it
71 started to get boring. A one pass assembler needs much more elaborated
72 data structures, and because of that it's much more fun:-)
73 <item> Non-GPLed code that may be used in any project without restrictions or
74 fear of "GPL infecting" other code.
82 <sect1>Command line option overview<p>
84 The assembler accepts the following options:
87 ---------------------------------------------------------------------------
88 Usage: ca65 [options] file
90 -D name[=value] Define a symbol
91 -I dir Set an include directory search path
92 -U Mark unresolved symbols as import
93 -V Print the assembler version
94 -W n Set warning level n
95 -g Add debug info to object file
97 -i Ignore case of symbols
98 -l Create a listing if assembly was ok
99 -mm model Set the memory model
100 -o name Name the output file
102 -t sys Set the target system
103 -v Increase verbosity
106 --auto-import Mark unresolved symbols as import
107 --cpu type Set cpu type
108 --debug-info Add debug info to object file
109 --feature name Set an emulation feature
110 --help Help (this text)
111 --ignore-case Ignore case of symbols
112 --include-dir dir Set an include directory search path
113 --listing Create a listing if assembly was ok
114 --list-bytes n Maximum number of bytes per listing line
115 --macpack-dir dir Set a macro package directory
116 --memory-model model Set the memory model
117 --pagelength n Set the page length for the listing
118 --smart Enable smart mode
119 --target sys Set the target system
120 --verbose Increase verbosity
121 --version Print the assembler version
122 ---------------------------------------------------------------------------
126 <sect1>Command line options in detail<p>
128 Here is a description of all the command line options:
132 <label id="option--cpu">
133 <tag><tt>--cpu type</tt></tag>
135 Set the default for the CPU type. The option takes a parameter, which
138 6502, 65SC02, 65C02, 65816, sunplus, sweet16, HuC6280
140 The sunplus cpu is not available in the freeware version, because the
141 instruction set is "proprietary and confidential".
144 <label id="option--feature">
145 <tag><tt>--feature name</tt></tag>
147 Enable an emulation feature. This is identical as using <tt/.FEATURE/
148 in the source with two exceptions: Feature names must be lower case, and
149 each feature must be specified by using an extra <tt/--feature/ option,
150 comma separated lists are not allowed.
152 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
153 command for a list of emulation features.
156 <label id="option-g">
157 <tag><tt>-g, --debug-info</tt></tag>
159 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
160 used, the assembler will add a section to the object file that contains
161 all symbols (including local ones) together with the symbol values and
162 source file positions. The linker will put these additional symbols into
163 the VICE label file, so even local symbols can be seen in the VICE
167 <tag><tt>-h, --help</tt></tag>
169 Print the short option summary shown above.
172 <tag><tt>-i, --ignore-case</tt></tag>
174 This option makes the assembler case insensitive on identifiers and labels.
175 This option will override the default, but may itself be overridden by the
176 <tt><ref id=".CASE" name=".CASE"></tt> control command.
179 <tag><tt>-l, --listing</tt></tag>
181 Generate an assembler listing. The listing file will always have the
182 name of the main input file with the extension replaced by ".lst". This
183 may change in future versions.
186 <tag><tt>--list-bytes n</tt></tag>
188 Set the maximum number of bytes printed in the listing for one line of
189 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
190 for more information. The value zero can be used to encode an unlimited
191 number of printed bytes.
194 <tag><tt>--macpack-dir dir</tt></tag>
196 This options allows to specify a directory containing macro files that are
197 used instead of the builtin images when a <tt><ref id=".MACPACK"
198 name=".MACPACK"></tt> directive is encountered. If <tt>--macpack-dir</tt>
199 was specified, a <tt>.mac</tt> extension is added to the package name and
200 the resulting file is loaded from the given directory. This is most useful
201 when debugging the builtin macro packages.
204 <tag><tt>-mm model, --memory-model model</tt></tag>
206 Define the default memory model. Possible model specifiers are near, far and
210 <tag><tt>-o name</tt></tag>
212 The default output name is the name of the input file with the extension
213 replaced by ".o". If you don't like that, you may give another name with
214 the -o option. The output file will be placed in the same directory as
215 the source file, or, if -o is given, the full path in this name is used.
218 <tag><tt>--pagelength n</tt></tag>
220 sets the length of a listing page in lines. See the <tt><ref
221 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
224 <tag><tt>-s, --smart-mode</tt></tag>
226 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
227 pseudo instruction) the assembler will track usage of the <tt/REP/ and
228 <tt/SEP/ instructions in 65816 mode and update the operand sizes
229 accordingly. If the operand of such an instruction cannot be evaluated by
230 the assembler (for example, because the operand is an imported symbol), a
233 Beware: Since the assembler cannot trace the execution flow this may
234 lead to false results in some cases. If in doubt, use the .ixx and .axx
235 instructions to tell the assembler about the current settings. Smart
236 mode is off by default.
239 <label id="option-t">
240 <tag><tt>-t sys, --target sys</tt></tag>
242 Set the target system. This will enable translation of character strings
243 and character constants into the character set of the target platform.
244 The default for the target system is "none", which means that no translation
245 will take place. The assembler supports the same target systems as the
246 compiler, see there for a list.
249 <tag><tt>-v, --verbose</tt></tag>
251 Increase the assembler verbosity. Usually only needed for debugging
252 purposes. You may use this option more than one time for even more
256 <tag><tt>-D</tt></tag>
258 This option allows you to define symbols on the command line. Without a
259 value, the symbol is defined with the value zero. When giving a value,
260 you may use the '$' prefix for hexadecimal symbols. Please note
261 that for some operating systems, '$' has a special meaning, so
262 you may have to quote the expression.
265 <tag><tt>-I dir, --include-dir dir</tt></tag>
267 Name a directory which is searched for include files. The option may be
268 used more than once to specify more than one directory to search. The
269 current directory is always searched first before considering any
270 additional directories.
273 <tag><tt>-U, --auto-import</tt></tag>
275 Mark symbols that are not defined in the sources as imported symbols. This
276 should be used with care since it delays error messages about typos and such
277 until the linker is run. The compiler uses the equivalent of this switch
278 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
279 symbols for the runtime library. However, the compiler is supposed to
280 generate code that runs through the assembler without problems, something
281 which is not always true for assembler programmers.
284 <tag><tt>-V, --version</tt></tag>
286 Print the version number of the assembler. If you send any suggestions
287 or bugfixes, please include the version number.
290 <label id="option-W">
291 <tag><tt>-Wn</tt></tag>
293 Set the warning level for the assembler. Using -W2 the assembler will
294 even warn about such things like unused imported symbols. The default
295 warning level is 1, and it would probably be silly to set it to
302 <sect>Input format<p>
304 <sect1>Assembler syntax<p>
306 The assembler accepts the standard 6502/65816 assembler syntax. One line may
307 contain a label (which is identified by a colon), and, in addition to the
308 label, an assembler mnemonic, a macro, or a control command (see section <ref
309 id="control-commands" name="Control Commands"> for supported control
310 commands). Alternatively, the line may contain a symbol definition using
311 the '=' token. Everything after a semicolon is handled as a comment (that is,
314 Here are some examples for valid input lines:
317 Label: ; A label and a comment
318 lda #$20 ; A 6502 instruction plus comment
319 L1: ldx #$20 ; Same with label
320 L2: .byte "Hello world" ; Label plus control command
321 mymac $20 ; Macro expansion
322 MySym = 3*L1 ; Symbol definition
323 MaSym = Label ; Another symbol
326 The assembler accepts
329 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
330 <tt><ref id=".P02" name=".P02"></tt> command was given).
331 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
332 <ref id="6502X-mode" name="6502X mode">.
333 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
334 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
335 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
336 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
337 <item>all valid 65618 mnemonics when in 65816 mode (after the
338 <tt><ref id=".P816" name=".P816"></tt> command was given).
339 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
340 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
346 In 65816 mode several aliases are accepted in addition to the official
350 BGE is an alias for BCS
351 BLT is an alias for BCC
352 CPA is an alias for CMP
353 DEA is an alias for DEC A
354 INA is an alias for INC A
355 SWA is an alias for XBA
356 TAD is an alias for TCD
357 TAS is an alias for TCS
358 TDA is an alias for TDC
359 TSA is an alias for TSC
364 <sect1>6502X mode<label id="6502X-mode"><p>
366 6502X mode is an extension to the normal 6502 mode. In this mode, several
367 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
368 these instructions are illegal, there are no official mnemonics for them. The
369 unofficial ones are taken from <htmlurl
370 url="http://oxyron.net/graham/opcodes02.html"
371 name="http://oxyron.net/graham/opcodes02.html">. Please note that only the
372 ones marked as "stable" are supported. The following table uses information
373 from the mentioned web page, for more information, see there.
376 <item><tt>ALR: A:=(A and #{imm})*2;</tt>
377 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
378 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
379 <item><tt>AXS: X:=A and X-#{imm};</tt>
380 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
381 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
382 <item><tt>LAS: A,X,S:={adr} and S;</tt>
383 <item><tt>LAX: A,X:={adr};</tt>
384 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
385 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
386 <item><tt>SAX: {adr}:=A and X;</tt>
387 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
388 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
393 <sect1>sweet16 mode<label id="sweet16-mode"><p>
395 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
396 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
397 generate code for this pseudo CPU when switched into sweet16 mode. The
398 following is special in sweet16 mode:
402 <item>The '@' character denotes indirect addressing and is no longer available
403 for cheap local labels. If you need cheap local labels, you will have to
404 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
405 name=".LOCALCHAR">/ command.
407 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
408 these identifiers are reserved words.
412 Please note that the assembler does neither supply the interpreter needed for
413 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
414 nor does it call the interpreter. All this must be done by your program. Apple
415 ][ programmers do probably know how to use sweet16 mode.
417 For more information about SWEET 16, see
418 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
419 name="http://www.6502.org/source/interpreters/sweet16.htm">.
422 <sect1>Number format<p>
424 For literal values, the assembler accepts the widely used number formats: A
425 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
426 denotes a binary value, and a bare number is interpreted as a decimal. There
427 are currently no octal values and no floats.
430 <sect1>Conditional assembly<p>
432 Please note that when using the conditional directives (<tt/.IF/ and friends),
433 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
434 that are not assembled. The reason for this behaviour is that the assembler
435 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
436 conversion of the input stream into tokens still takes place. As a consequence
437 conditional assembly directives may <bf/not/ be used to prevent normal text
438 (used as a comment or similar) from being assembled. <p>
444 <sect1>Expression evaluation<p>
446 All expressions are evaluated with (at least) 32 bit precision. An
447 expression may contain constant values and any combination of internal and
448 external symbols. Expressions that cannot be evaluated at assembly time
449 are stored inside the object file for evaluation by the linker.
450 Expressions referencing imported symbols must always be evaluated by the
454 <sect1>Size of an expression result<p>
456 Sometimes, the assembler must know about the size of the value that is the
457 result of an expression. This is usually the case, if a decision has to be
458 made, to generate a zero page or an absolute memory references. In this
459 case, the assembler has to make some assumptions about the result of an
463 <item> If the result of an expression is constant, the actual value is
464 checked to see if it's a byte sized expression or not.
465 <item> If the expression is explicitly casted to a byte sized expression by
466 one of the '>', '<' or '^' operators, it is a byte expression.
467 <item> If this is not the case, and the expression contains a symbol,
468 explicitly declared as zero page symbol (by one of the .importzp or
469 .exportzp instructions), then the whole expression is assumed to be
471 <item> If the expression contains symbols that are not defined, and these
472 symbols are local symbols, the enclosing scopes are searched for a
473 symbol with the same name. If one exists and this symbol is defined,
474 it's attributes are used to determine the result size.
475 <item> In all other cases the expression is assumed to be word sized.
478 Note: If the assembler is not able to evaluate the expression at assembly
479 time, the linker will evaluate it and check for range errors as soon as
483 <sect1>Boolean expressions<p>
485 In the context of a boolean expression, any non zero value is evaluated as
486 true, any other value to false. The result of a boolean expression is 1 if
487 it's true, and zero if it's false. There are boolean operators with extreme
488 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
489 operators are shortcut operators. That is, if the result of the expression is
490 already known, after evaluating the left hand side, the right hand side is
494 <sect1>Constant expressions<p>
496 Sometimes an expression must evaluate to a constant without looking at any
497 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
498 that decides if parts of the code are assembled or not. An expression used in
499 the <tt/.IF/ command cannot reference a symbol defined later, because the
500 decision about the <tt/.IF/ must be made at the point when it is read. If the
501 expression used in such a context contains only constant numerical values,
502 there is no problem. When unresolvable symbols are involved it may get harder
503 for the assembler to determine if the expression is actually constant, and it
504 is even possible to create expressions that aren't recognized as constant.
505 Simplifying the expressions will often help.
507 In cases where the result of the expression is not needed immediately, the
508 assembler will delay evaluation until all input is read, at which point all
509 symbols are known. So using arbitrary complex constant expressions is no
510 problem in most cases.
514 <sect1>Available operators<label id="operators"><p>
518 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
519 | Built-in string functions| 0@
521 | Built-in pseudo-variables| 1@
522 | Built-in pseudo-functions| 1@
523 +| Unary positive| 1@
524 -| Unary negative| 1@
526 .BITNOT| Unary bitwise not| 1@
528 .LOBYTE| Unary low-byte operator| 1@
530 .HIBYTE| Unary high-byte operator| 1@
532 .BANKBYTE| Unary bank-byte operator| 1@
534 *| Multiplication| 2@
536 .MOD| Modulo operator| 2@
538 .BITAND| Bitwise and| 2@
540 .BITXOR| Binary bitwise xor| 2@
542 .SHL| Shift-left operator| 2@
544 .SHR| Shift-right operator| 2@
546 +| Binary addition| 3@
547 -| Binary subtraction| 3@
549 .BITOR| Bitwise or| 3@
551 = | Compare operator (equal)| 4@
552 <>| Compare operator (not equal)| 4@
553 <| Compare operator (less)| 4@
554 >| Compare operator (greater)| 4@
555 <=| Compare operator (less or equal)| 4@
556 >=| Compare operator (greater or equal)| 4@
559 .AND| Boolean and| 5@
560 .XOR| Boolean xor| 5@
562 ||<newline>
566 .NOT| Boolean not| 7@<hline>
568 <caption>Available operators, sorted by precedence
571 To force a specific order of evaluation, parentheses may be used, as usual.
575 <sect>Symbols and labels<p>
577 A symbol or label is an identifier that starts with a letter and is followed
578 by letters and digits. Depending on some features enabled (see
579 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
580 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
581 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
582 other characters may be present. Use of identifiers consisting of a single
583 character will not work in all cases, because some of these identifiers are
584 reserved keywords (for example "A" is not a valid identifier for a label,
585 because it is the keyword for the accumulator).
587 The assembler allows you to use symbols instead of naked values to make
588 the source more readable. There are a lot of different ways to define and
589 use symbols and labels, giving a lot of flexibility.
591 <sect1>Numeric constants<p>
593 Numeric constants are defined using the equal sign or the label assignment
594 operator. After doing
600 may use the symbol "two" in every place where a number is expected, and it is
601 evaluated to the value 2 in this context. The label assignment operator causes
602 the same, but causes the symbol to be marked as a label, which may cause a
603 different handling in the debugger:
609 The right side can of course be an expression:
616 <sect1>Standard labels<p>
618 A label is defined by writing the name of the label at the start of the line
619 (before any instruction mnemonic, macro or pseudo directive), followed by a
620 colon. This will declare a symbol with the given name and the value of the
621 current program counter.
624 <sect1>Local labels and symbols<p>
626 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
627 create regions of code where the names of labels and symbols are local to this
628 region. They are not known outside of this region and cannot be accessed from
629 there. Such regions may be nested like PROCEDUREs in Pascal.
631 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
632 directive for more information.
635 <sect1>Cheap local labels<p>
637 Cheap local labels are defined like standard labels, but the name of the
638 label must begin with a special symbol (usually '@', but this can be
639 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
642 Cheap local labels are visible only between two non cheap labels. As soon as a
643 standard symbol is encountered (this may also be a local symbol if inside a
644 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
645 cheap local symbol goes out of scope.
647 You may use cheap local labels as an easy way to reuse common label
648 names like "Loop". Here is an example:
651 Clear: lda #$00 ; Global label
653 @Loop: sta Mem,y ; Local label
657 Sub: ... ; New global label
658 bne @Loop ; ERROR: Unknown identifier!
661 <sect1>Unnamed labels<p>
663 If you really want to write messy code, there are also unnamed labels. These
664 labels do not have a name (you guessed that already, didn't you?). A colon is
665 used to mark the absence of the name.
667 Unnamed labels may be accessed by using the colon plus several minus or plus
668 characters as a label designator. Using the '-' characters will create a back
669 reference (use the n'th label backwards), using '+' will create a forward
670 reference (use the n'th label in forward direction). An example will help to
693 As you can see from the example, unnamed labels will make even short
694 sections of code hard to understand, because you have to count labels
695 to find branch targets (this is the reason why I for my part do
696 prefer the "cheap" local labels). Nevertheless, unnamed labels are
697 convenient in some situations, so it's your decision.
700 <sect1>Using macros to define labels and constants<p>
702 While there are drawbacks with this approach, it may be handy in some
703 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
704 possible to define symbols or constants that may be used elsewhere. Since
705 the macro facility works on a very low level, there is no scoping. On the
706 other side, you may also define string constants this way (this is not
707 possible with the other symbol types).
713 .DEFINE version "SOS V2.3"
715 four = two * two ; Ok
718 .PROC ; Start local scope
719 two = 3 ; Will give "2 = 3" - invalid!
724 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
726 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
727 id="option-g" name="-g"> is given on the command line), global, local and
728 cheap local labels are written to the object file and will be available in the
729 symbol file via the linker. Unnamed labels are not written to the object file,
730 because they don't have a name which would allow to access them.
734 <sect>Scopes<label id="scopes"><p>
736 ca65 implements several sorts of scopes for symbols.
738 <sect1>Global scope<p>
740 All (non cheap local) symbols that are declared outside of any nested scopes
744 <sect1>Cheap locals<p>
746 A special scope is the scope for cheap local symbols. It lasts from one non
747 local symbol to the next one, without any provisions made by the programmer.
748 All other scopes differ in usage but use the same concept internally.
751 <sect1>Generic nested scopes<p>
753 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
754 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
755 The scope can have a name, in which case it is accessible from the outside by
756 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
757 have a name, all symbols created within the scope are local to the scope, and
758 aren't accessible from the outside.
760 A nested scope can access symbols from the local or from enclosing scopes by
761 name without using explicit scope names. In some cases there may be
762 ambiguities, for example if there is a reference to a local symbol that is not
763 yet defined, but a symbol with the same name exists in outer scopes:
775 In the example above, the <tt/lda/ instruction will load the value 3 into the
776 accumulator, because <tt/foo/ is redefined in the scope. However:
788 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
789 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
790 absolute mode is used instead. In fact, the assembler will not use absolute
791 mode by default, but it will search through the enclosing scopes for a symbol
792 with the given name. If one is found, the address size of this symbol is used.
793 This may lead to errors:
805 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
806 instruction, it will search for an already defined symbol <tt/foo/. It will
807 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
808 zeropage symbol. So the assembler will use zeropage addressing mode. If
809 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
810 the address in the <tt/lda/ instruction already translated, but since the new
811 value needs absolute addressing mode, this fails, and an error message "Range
814 Of course the most simple solution for the problem is to move the definition
815 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
816 rare cases when this cannot be done. In these cases, you can use one of the
817 address size override operators:
829 This will cause the <tt/lda/ instruction to be translated using absolute
830 addressing mode, which means changing the symbol reference later does not
834 <sect1>Nested procedures<p>
836 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
837 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
838 name, and a it will introduce a symbol with this name in the enclosing scope.
847 is actually the same as
856 This is the reason why a procedure must have a name. If you want a scope
857 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
859 <bf/Note:/ As you can see from the example above, scopes and symbols live in
860 different namespaces. There can be a symbol named <tt/foo/ and a scope named
861 <tt/foo/ without any conflicts (but see the section titled <ref
862 id="scopesearch" name=""Scope search order"">).
865 <sect1>Structs, unions and enums<p>
867 Structs, unions and enums are explained in a <ref id="structs" name="separate
868 section">, I do only cover them here, because if they are declared with a
869 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
870 name=".SCOPE">/. However, when no name is specified, the behaviour is
871 different: In this case, no new scope will be opened, symbols declared within
872 a struct, union, or enum declaration will then be added to the enclosing scope
876 <sect1>Explicit scope specification<label id="scopesyntax"><p>
878 Accessing symbols from other scopes is possible by using an explicit scope
879 specification, provided that the scope where the symbol lives in has a name.
880 The namespace token (<tt/::/) is used to access other scopes:
888 lda foo::bar ; Access foo in scope bar
891 The only way to deny access to a scope from the outside is to declare a scope
892 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
894 A special syntax is used to specify the global scope: If a symbol or scope is
895 preceded by the namespace token, the global scope is searched:
902 lda #::bar ; Access the global bar (which is 3)
907 <sect1>Scope search order<label id="scopesearch"><p>
909 The assembler searches for a scope in a similar way as for a symbol. First, it
910 looks in the current scope, and then it walks up the enclosing scopes until
913 However, one important thing to note when using explicit scope syntax is, that
914 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
915 used without a preceding definition. This means that in the following
924 lda #foo::bar ; Will load 3, not 2!
931 the reference to the scope <tt/foo/ will use the global scope, and not the
932 local one, because the local one is not visible at the point where it is
935 Things get more complex if a complete chain of scopes is specified:
946 lda #outer::inner::bar ; 1
958 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
959 assembler will first search in the local scope for a scope named <tt/outer/.
960 Since none is found, the enclosing scope (<tt/another/) is checked. There is
961 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
962 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
963 this scope, the assembler looks for a symbol named <tt/bar/.
965 Please note that once the anchor scope is found, all following scopes
966 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
967 assembler will search the scope tree only for the first scope (if it is not
968 anchored in the root scope). Starting from there on, there is no flexibility,
969 so if the scope named <tt/outer/ found by the assembler does not contain a
970 scope named <tt/inner/, this would be an error, even if such a pair does exist
971 (one level up in global scope).
973 Ambiguities that may be introduced by this search algorithm may be removed by
974 anchoring the scope specification in the global scope. In the example above,
975 if you want to access the "other" symbol <tt/bar/, you would have to write:
986 lda #::outer::inner::bar ; 2
999 <sect>Address sizes and memory models<label id="address-sizes"><p>
1001 <sect1>Address sizes<p>
1003 ca65 assigns each segment and each symbol an address size. This is true, even
1004 if the symbol is not used as an address. You may also think of a value range
1005 of the symbol instead of an address size.
1007 Possible address sizes are:
1010 <item>Zeropage or direct (8 bits)
1011 <item>Absolute (16 bits)
1013 <item>Long (32 bits)
1016 Since the assembler uses default address sizes for the segments and symbols,
1017 it is usually not necessary to override the default behaviour. In cases, where
1018 it is necessary, the following keywords may be used to specify address sizes:
1021 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1022 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1023 <item>FAR for far addressing (24 bits).
1024 <item>LONG or DWORD for long addressing (32 bits).
1028 <sect1>Address sizes of segments<p>
1030 The assembler assigns an address size to each segment. Since the
1031 representation of a label within this segment is "segment start + offset",
1032 labels will inherit the address size of the segment they are declared in.
1034 The address size of a segment may be changed, by using an optional address
1035 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1036 an explanation on how this is done.
1039 <sect1>Address sizes of symbols<p>
1044 <sect1>Memory models<p>
1046 The default address size of a segment depends on the memory model used. Since
1047 labels inherit the address size from the segment they are declared in,
1048 changing the memory model is an easy way to change the address size of many
1054 <sect>Pseudo variables<label id="pseudo-variables"><p>
1056 Pseudo variables are readable in all cases, and in some special cases also
1059 <sect1><tt>*</tt><p>
1061 Reading this pseudo variable will return the program counter at the start
1062 of the current input line.
1064 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1065 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1066 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1069 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1071 Reading this pseudo variable will give a constant integer value that
1072 tells which CPU is currently enabled. It can also tell which instruction
1073 set the CPU is able to translate. The value read from the pseudo variable
1074 should be further examined by using one of the constants defined by the
1075 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1077 It may be used to replace the .IFPxx pseudo instructions or to construct
1078 even more complex expressions.
1084 .if (.cpu .bitand CPU_ISET_65816)
1096 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1098 This builtin pseudo variable is only available in macros. It is replaced by
1099 the actual number of parameters that were given in the macro invocation.
1104 .macro foo arg1, arg2, arg3
1105 .if .paramcount <> 3
1106 .error "Too few parameters for macro foo"
1112 See section <ref id="macros" name="Macros">.
1115 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1117 Reading this pseudo variable will give a constant integer value that
1118 represents the current time in POSIX standard (as seconds since the
1121 It may be used to encode the time of translation somewhere in the created
1127 .dword .time ; Place time here
1131 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1133 Reading this pseudo variable will give the assembler version according to
1134 the following formula:
1136 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1138 It may be used to encode the assembler version or check the assembler for
1139 special features not available with older versions.
1143 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1144 reading the pseudo variable <tt/.VERSION/.
1148 <sect>Pseudo functions<label id="pseudo-functions"><p>
1150 Pseudo functions expect their arguments in parenthesis, and they have a result,
1151 either a string or an expression.
1154 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1156 The function returns the bank byte (that is, bits 16-23) of its argument.
1157 It works identical to the '^' operator.
1159 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1160 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1163 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1165 Builtin function. The function evaluates its argument in braces and yields
1166 "false" if the argument is non blank (there is an argument), and "true" if
1167 there is no argument. The token list that makes up the function argument
1168 may optionally be enclosed in curly braces. This allows the inclusion of
1169 tokens that would otherwise terminate the list (the closing right
1170 parenthesis). The curly braces are not considered part of the list, a list
1171 just consisting of curly braces is considered to be empty.
1173 As an example, the <tt/.IFBLANK/ statement may be replaced by
1181 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1183 Builtin string function. The function allows to concatenate a list of string
1184 constants separated by commas. The result is a string constant that is the
1185 concatenation of all arguments. This function is most useful in macros and
1186 when used together with the <tt/.STRING/ builtin function. The function may
1187 be used in any case where a string constant is expected.
1192 .include .concat ("myheader", ".", "inc")
1195 This is the same as the command
1198 .include "myheader.inc"
1202 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1204 Builtin function. The function evaluates its argument in braces and
1205 yields "true" if the argument is a constant expression (that is, an
1206 expression that yields a constant value at assembly time) and "false"
1207 otherwise. As an example, the .IFCONST statement may be replaced by
1214 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1216 The function returns the high byte (that is, bits 8-15) of its argument.
1217 It works identical to the '>' operator.
1219 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1220 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1223 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1225 The function returns the high word (that is, bits 16-31) of its argument.
1227 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1230 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1232 The function expects a string as its argument, and converts this argument
1233 into an identifier. If the string starts with the current <tt/<ref
1234 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1235 identifier, otherwise it will be converted into a normal identifier.
1240 .macro makelabel arg1, arg2
1241 .ident (.concat (arg1, arg2)):
1244 makelabel "foo", "bar"
1246 .word foobar ; Valid label
1250 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1252 Builtin function. Extracts the left part of a given token list.
1257 .LEFT (<int expr>, <token list>)
1260 The first integer expression gives the number of tokens to extract from
1261 the token list. The second argument is the token list itself. The token
1262 list may optionally be enclosed into curly braces. This allows the
1263 inclusion of tokens that would otherwise terminate the list (the closing
1264 right paren in the given case).
1268 To check in a macro if the given argument has a '#' as first token
1269 (immediate addressing mode), use something like this:
1274 .if (.match (.left (1, {arg}), #))
1276 ; ldax called with immediate operand
1284 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1285 name=".RIGHT"></tt> builtin functions.
1288 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1290 The function returns the low byte (that is, bits 0-7) of its argument.
1291 It works identical to the '<' operator.
1293 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1294 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1297 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1299 The function returns the low word (that is, bits 0-15) of its argument.
1301 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1304 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1306 Builtin function. Matches two token lists against each other. This is
1307 most useful within macros, since macros are not stored as strings, but
1313 .MATCH(<token list #1>, <token list #2>)
1316 Both token list may contain arbitrary tokens with the exception of the
1317 terminator token (comma resp. right parenthesis) and
1324 The token lists may optionally be enclosed into curly braces. This allows
1325 the inclusion of tokens that would otherwise terminate the list (the closing
1326 right paren in the given case). Often a macro parameter is used for any of
1329 Please note that the function does only compare tokens, not token
1330 attributes. So any number is equal to any other number, regardless of the
1331 actual value. The same is true for strings. If you need to compare tokens
1332 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1333 name=".XMATCH"></tt> function.
1337 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1338 while honoring the sign bit. The builtin processor instructions will allow
1339 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1340 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1341 to check for this and print and error for invalid calls.
1346 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1347 .error "Syntax error"
1350 cmp #$80 ; Bit 7 into carry
1351 lsr a ; Shift carry into bit 7
1356 The macro will only accept no arguments, or one argument that must be the
1357 reserved keyword "A".
1359 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1362 <sect1><tt>.MID</tt><label id=".MID"><p>
1364 Builtin function. Takes a starting index, a count and a token list as
1365 arguments. Will return part of the token list.
1370 .MID (<int expr>, <int expr>, <token list>)
1373 The first integer expression gives the starting token in the list (the first
1374 token has index 0). The second integer expression gives the number of tokens
1375 to extract from the token list. The third argument is the token list itself.
1376 The token list may optionally be enclosed into curly braces. This allows the
1377 inclusion of tokens that would otherwise terminate the list (the closing
1378 right paren in the given case).
1382 To check in a macro if the given argument has a '<tt/#/' as first token
1383 (immediate addressing mode), use something like this:
1388 .if (.match (.mid (0, 1, {arg}), #))
1390 ; ldax called with immediate operand
1398 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1399 name=".RIGHT"></tt> builtin functions.
1402 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1404 Builtin function. The function expects an identifier as argument in braces.
1405 The argument is evaluated, and the function yields "true" if the identifier
1406 is a symbol that has already been referenced somewhere in the source file up
1407 to the current position. Otherwise the function yields false. As an example,
1408 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1414 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1417 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1419 Builtin function. Extracts the right part of a given token list.
1424 .RIGHT (<int expr>, <token list>)
1427 The first integer expression gives the number of tokens to extract from the
1428 token list. The second argument is the token list itself. The token list
1429 may optionally be enclosed into curly braces. This allows the inclusion of
1430 tokens that would otherwise terminate the list (the closing right paren in
1433 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1434 name=".MID"></tt> builtin functions.
1437 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1439 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1440 argument can be a struct/union, a struct member, a procedure, or a label. In
1441 case of a procedure or label, its size is defined by the amount of data
1442 placed in the segment where the label is relative to. If a line of code
1443 switches segments (for example in a macro) data placed in other segments
1444 does not count for the size.
1446 Please note that a symbol or scope must exist, before it is used together with
1447 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1448 A scope has preference over a symbol with the same name, so if the last part
1449 of a name represents both, a scope and a symbol, the scope is chosen over the
1452 After the following code:
1455 .struct Point ; Struct size = 4
1460 P: .tag Point ; Declare a point
1461 @P: .tag Point ; Declare another point
1473 .data ; Segment switch!!!
1479 <tag><tt/.sizeof(Point)/</tag>
1480 will have the value 4, because this is the size of struct <tt/Point/.
1482 <tag><tt/.sizeof(Point::xcoord)/</tag>
1483 will have the value 2, because this is the size of the member <tt/xcoord/
1484 in struct <tt/Point/.
1486 <tag><tt/.sizeof(P)/</tag>
1487 will have the value 4, this is the size of the data declared on the same
1488 source line as the label <tt/P/, which is in the same segment that <tt/P/
1491 <tag><tt/.sizeof(@P)/</tag>
1492 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1493 does also work for cheap local symbols.
1495 <tag><tt/.sizeof(Code)/</tag>
1496 will have the value 3, since this is amount of data emitted into the code
1497 segment, the segment that was active when <tt/Code/ was entered. Note that
1498 this value includes the amount of data emitted in child scopes (in this
1499 case <tt/Code::Inner/).
1501 <tag><tt/.sizeof(Code::Inner)/</tag>
1502 will have the value 1 as expected.
1504 <tag><tt/.sizeof(Data)/</tag>
1505 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1506 the segment is switched after entry, this data is emitted into another
1511 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1513 Builtin function. The function accepts a string and an index as
1514 arguments and returns the value of the character at the given position
1515 as an integer value. The index is zero based.
1521 ; Check if the argument string starts with '#'
1522 .if (.strat (Arg, 0) = '#')
1529 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1531 Builtin function. It expects a format string as first argument. The number
1532 and type of the following arguments depend on the format string. The format
1533 string is similar to the one of the C <tt/printf/ function. Missing things
1534 are: Length modifiers, variable width.
1536 The result of the function is a string.
1543 ; Generate an identifier:
1544 .ident (.sprintf ("%s%03d", "label", num)):
1548 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1550 Builtin function. The function accepts an argument in braces and converts
1551 this argument into a string constant. The argument may be an identifier, or
1552 a constant numeric value.
1554 Since you can use a string in the first place, the use of the function may
1555 not be obvious. However, it is useful in macros, or more complex setups.
1560 ; Emulate other assemblers:
1562 .segment .string(name)
1567 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1569 Builtin function. The function accepts a string argument in braces and
1570 evaluates to the length of the string.
1574 The following macro encodes a string as a pascal style string with
1575 a leading length byte.
1579 .byte .strlen(Arg), Arg
1584 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1586 Builtin function. The function accepts a token list in braces. The function
1587 result is the number of tokens given as argument. The token list may
1588 optionally be enclosed into curly braces which are not considered part of
1589 the list and not counted. Enclosement in curly braces allows the inclusion
1590 of tokens that would otherwise terminate the list (the closing right paren
1595 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1596 with the normal 6502 instructions). To translate it into two separate 8 bit
1597 load instructions, the '#' token has to get stripped from the argument:
1601 .if (.match (.mid (0, 1, {arg}), #))
1602 ; ldax called with immediate operand
1603 lda #<(.right (.tcount ({arg})-1, {arg}))
1604 ldx #>(.right (.tcount ({arg})-1, {arg}))
1612 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1614 Builtin function. Matches two token lists against each other. This is
1615 most useful within macros, since macros are not stored as strings, but
1621 .XMATCH(<token list #1>, <token list #2>)
1624 Both token list may contain arbitrary tokens with the exception of the
1625 terminator token (comma resp. right parenthesis) and
1632 The token lists may optionally be enclosed into curly braces. This allows
1633 the inclusion of tokens that would otherwise terminate the list (the closing
1634 right paren in the given case). Often a macro parameter is used for any of
1637 The function compares tokens <em/and/ token values. If you need a function
1638 that just compares the type of tokens, have a look at the <tt><ref
1639 id=".MATCH" name=".MATCH"></tt> function.
1641 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1645 <sect>Control commands<label id="control-commands"><p>
1647 Here's a list of all control commands and a description, what they do:
1650 <sect1><tt>.A16</tt><label id=".A16"><p>
1652 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1654 Note: This command will not emit any code, it will tell the assembler to
1655 create 16 bit operands for immediate accumulator addressing mode.
1657 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1660 <sect1><tt>.A8</tt><label id=".A8"><p>
1662 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1664 Note: This command will not emit any code, it will tell the assembler to
1665 create 8 bit operands for immediate accu addressing mode.
1667 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1670 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1672 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1673 may be used for better readability if the data words are address values. In
1674 65816 mode, the address is forced to be 16 bit wide to fit into the current
1675 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1676 must be followed by a sequence of (not necessarily constant) expressions.
1681 .addr $0D00, $AF13, _Clear
1684 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1688 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1690 Align data to a given boundary. The command expects a constant integer
1691 argument that must be a power of two, plus an optional second argument
1692 in byte range. If there is a second argument, it is used as fill value,
1693 otherwise the value defined in the linker configuration file is used
1694 (the default for this value is zero).
1696 Since alignment depends on the base address of the module, you must
1697 give the same (or a greater) alignment for the segment when linking.
1698 The linker will give you a warning, if you don't do that.
1707 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1709 Define a string with a trailing zero.
1714 Msg: .asciiz "Hello world"
1717 This will put the string "Hello world" followed by a binary zero into
1718 the current segment. There may be more strings separated by commas, but
1719 the binary zero is only appended once (after the last one).
1722 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1724 Add an assertion. The command is followed by an expression, an action
1725 specifier, and an optional message that is output in case the assertion
1726 fails. If no message was given, the string "Assertion failed" is used. The
1727 action specifier may be one of <tt/warning/ or <tt/error/. The assertion is
1728 evaluated by the assembler if possible, and also passed to the linker in the
1729 object file (if one is generated). The linker will then evaluate the
1730 expression when segment placement has been done.
1735 .assert * = $8000, error, "Code not at $8000"
1738 The example assertion will check that the current location is at $8000,
1739 when the output file is written, and abort with an error if this is not
1740 the case. More complex expressions are possible. The action specifier
1741 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1742 an error message. In the latter case, generation of the output file is
1743 suppressed in both the assembler and linker.
1746 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1748 Is followed by a plus or a minus character. When switched on (using a
1749 +), undefined symbols are automatically marked as import instead of
1750 giving errors. When switched off (which is the default so this does not
1751 make much sense), this does not happen and an error message is
1752 displayed. The state of the autoimport flag is evaluated when the
1753 complete source was translated, before outputting actual code, so it is
1754 <em/not/ possible to switch this feature on or off for separate sections
1755 of code. The last setting is used for all symbols.
1757 You should probably not use this switch because it delays error
1758 messages about undefined symbols until the link stage. The cc65
1759 compiler (which is supposed to produce correct assembler code in all
1760 circumstances, something which is not true for most assembler
1761 programmers) will insert this command to avoid importing each and every
1762 routine from the runtime library.
1767 .autoimport + ; Switch on auto import
1770 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
1772 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
1773 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
1774 the operator '^' prepended to each expression in its list.
1779 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
1781 TableLookupLo: .lobytes MyTable
1782 TableLookupHi: .hibytes MyTable
1783 TableLookupBank: .bankbytes MyTable
1786 which is equivalent to
1789 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
1790 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
1791 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
1794 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
1795 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
1796 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
1799 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1801 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1802 so this is a shortcut for
1808 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1811 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1813 Define byte sized data. Must be followed by a sequence of (byte ranged)
1814 expressions or strings.
1820 .byt "world", $0D, $00
1824 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1826 Switch on or off case sensitivity on identifiers. The default is off
1827 (that is, identifiers are case sensitive), but may be changed by the
1828 -i switch on the command line.
1829 The command must be followed by a '+' or '-' character to switch the
1830 option on or off respectively.
1835 .case - ; Identifiers are not case sensitive
1839 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1841 Apply a custom mapping for characters. The command is followed by two
1842 numbers in the range 1..255. The first one is the index of the source
1843 character, the second one is the mapping. The mapping applies to all
1844 character and string constants when they generate output, and overrides
1845 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1846 command line switch.
1851 .charmap $41, $61 ; Map 'A' to 'a'
1855 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1857 Switch to the CODE segment. The name of the CODE segment is always
1858 "CODE", so this is a shortcut for
1864 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1867 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1869 Export a symbol and mark it in a special way. The linker is able to build
1870 tables of all such symbols. This may be used to automatically create a list
1871 of functions needed to initialize linked library modules.
1873 Note: The linker has a feature to build a table of marked routines, but it
1874 is your code that must call these routines, so just declaring a symbol with
1875 <tt/.CONDES/ does nothing by itself.
1877 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1878 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1879 is implied by <tt/.CONDES/.
1881 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1882 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1883 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1884 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1885 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1886 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
1887 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
1889 After the type, an optional priority may be specified. Higher numeric values
1890 mean higher priority. If no priority is given, the default priority of 7 is
1891 used. Be careful when assigning priorities to your own module constructors
1892 so they won't interfere with the ones in the cc65 library.
1897 .condes ModuleInit, constructor
1898 .condes ModInit, 0, 16
1901 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1902 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1903 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
1904 name="Module constructors/destructors"> explaining the feature in more
1908 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1910 Export a symbol and mark it as a module constructor. This may be used
1911 together with the linker to build a table of constructor subroutines that
1912 are called by the startup code.
1914 Note: The linker has a feature to build a table of marked routines, but it
1915 is your code that must call these routines, so just declaring a symbol as
1916 constructor does nothing by itself.
1918 A constructor is always exported as an absolute (16 bit) symbol. You don't
1919 need to use an additional <tt/.export/ statement, this is implied by
1920 <tt/.constructor/. It may have an optional priority that is separated by a
1921 comma. Higher numeric values mean a higher priority. If no priority is
1922 given, the default priority of 7 is used. Be careful when assigning
1923 priorities to your own module constructors so they won't interfere with the
1924 ones in the cc65 library.
1929 .constructor ModuleInit
1930 .constructor ModInit, 16
1933 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1934 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1935 <ref id="condes" name="Module constructors/destructors"> explaining the
1936 feature in more detail.
1939 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1941 Switch to the DATA segment. The name of the DATA segment is always
1942 "DATA", so this is a shortcut for
1948 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1951 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1953 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1954 create word sized data in native 65XX format). Must be followed by a
1955 sequence of (word ranged) expressions.
1963 This will emit the bytes
1969 into the current segment in that order.
1972 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1974 Switch on or off debug info generation. The default is off (that is,
1975 the object file will not contain debug infos), but may be changed by the
1976 -g switch on the command line.
1977 The command must be followed by a '+' or '-' character to switch the
1978 option on or off respectively.
1983 .debuginfo + ; Generate debug info
1987 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
1989 Start a define style macro definition. The command is followed by an
1990 identifier (the macro name) and optionally by a list of formal arguments
1992 See section <ref id="macros" name="Macros">.
1995 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
1997 Builtin function. The function expects an identifier as argument in braces.
1998 The argument is evaluated, and the function yields "true" if the identifier
1999 is a symbol that is already defined somewhere in the source file up to the
2000 current position. Otherwise the function yields false. As an example, the
2001 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2008 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2010 Export a symbol and mark it as a module destructor. This may be used
2011 together with the linker to build a table of destructor subroutines that
2012 are called by the startup code.
2014 Note: The linker has a feature to build a table of marked routines, but it
2015 is your code that must call these routines, so just declaring a symbol as
2016 constructor does nothing by itself.
2018 A destructor is always exported as an absolute (16 bit) symbol. You don't
2019 need to use an additional <tt/.export/ statement, this is implied by
2020 <tt/.destructor/. It may have an optional priority that is separated by a
2021 comma. Higher numerical values mean a higher priority. If no priority is
2022 given, the default priority of 7 is used. Be careful when assigning
2023 priorities to your own module destructors so they won't interfere with the
2024 ones in the cc65 library.
2029 .destructor ModuleDone
2030 .destructor ModDone, 16
2033 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2034 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2035 section <ref id="condes" name="Module constructors/destructors"> explaining
2036 the feature in more detail.
2039 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2041 Define dword sized data (4 bytes) Must be followed by a sequence of
2047 .dword $12344512, $12FA489
2051 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2053 Conditional assembly: Reverse the current condition.
2056 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2058 Conditional assembly: Reverse current condition and test a new one.
2061 <sect1><tt>.END</tt><label id=".END"><p>
2063 Forced end of assembly. Assembly stops at this point, even if the command
2064 is read from an include file.
2067 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2069 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2072 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2074 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2075 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2078 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2080 End of macro definition (see section <ref id="macros" name="Macros">).
2083 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2085 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2088 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2090 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2093 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2095 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2098 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2100 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2101 command and the separate section named <ref id="structs" name=""Structs
2105 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2107 Start an enumeration. This directive is very similar to the C <tt/enum/
2108 keyword. If a name is given, a new scope is created for the enumeration,
2109 otherwise the enumeration members are placed in the enclosing scope.
2111 In the enumeration body, symbols are declared. The first symbol has a value
2112 of zero, and each following symbol will get the value of the preceding plus
2113 one. This behaviour may be overridden by an explicit assignment. Two symbols
2114 may have the same value.
2126 Above example will create a new scope named <tt/errorcodes/ with three
2127 symbols in it that get the values 0, 1 and 2 respectively. Another way
2128 to write this would have been:
2138 Please note that explicit scoping must be used to access the identifiers:
2141 .word errorcodes::no_error
2144 A more complex example:
2153 EWOULDBLOCK = EAGAIN
2157 In this example, the enumeration does not have a name, which means that the
2158 members will be visible in the enclosing scope and can be used in this scope
2159 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2160 The value for the following members is incremented by one, so <tt/EOK/ would
2161 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2162 override for the value using an already defined symbol.
2165 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2167 Force an assembly error. The assembler will output an error message
2168 preceded by "User error" and will <em/not/ produce an object file.
2170 This command may be used to check for initial conditions that must be
2171 set before assembling a source file.
2181 .error "Must define foo or bar!"
2185 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2186 id=".OUT" name=".OUT"></tt> directives.
2189 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2191 Abort a macro expansion immediately. This command is often useful in
2192 recursive macros. See separate section <ref id="macros" name="Macros">.
2195 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2197 Make symbols accessible from other modules. Must be followed by a comma
2198 separated list of symbols to export, with each one optionally followed by an
2199 address specification and (also optional) an assignment. Using an additional
2200 assignment in the export statement allows to define and export a symbol in
2201 one statement. The default is to export the symbol with the address size it
2202 actually has. The assembler will issue a warning, if the symbol is exported
2203 with an address size smaller than the actual address size.
2210 .export foobar: far = foo * bar
2211 .export baz := foobar, zap: far = baz - bar
2214 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2217 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2220 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2222 Make symbols accessible from other modules. Must be followed by a comma
2223 separated list of symbols to export. The exported symbols are explicitly
2224 marked as zero page symbols. An assignment may be included in the
2225 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2232 .exportzp baz := $02
2235 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2238 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2240 Define far (24 bit) address data. The command must be followed by a
2241 sequence of (not necessarily constant) expressions.
2246 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2249 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2252 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2254 This directive may be used to enable one or more compatibility features
2255 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2256 possible, it may be useful when porting sources written for other
2257 assemblers. There is no way to switch a feature off, once you have
2258 enabled it, so using
2264 will enable the feature until end of assembly is reached.
2266 The following features are available:
2270 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2272 Accept the at character (`@') as a valid character in identifiers. The
2273 at character is not allowed to start an identifier, even with this
2276 <tag><tt>c_comments</tt></tag>
2278 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2279 comment terminators. Note that C comments may not be nested. There's also a
2280 pitfall when using C like comments: All statements must be terminated by
2281 "end-of-line". Using C like comments, it is possible to hide the newline,
2282 which results in error messages. See the following non working example:
2285 lda #$00 /* This comment hides the newline
2289 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2291 Accept the dollar sign (`$') as a valid character in identifiers. The
2292 dollar character is not allowed to start an identifier, even with this
2295 <tag><tt>dollar_is_pc</tt></tag>
2297 The dollar sign may be used as an alias for the star (`*'), which
2298 gives the value of the current PC in expressions.
2299 Note: Assignment to the pseudo variable is not allowed.
2301 <tag><tt>labels_without_colons</tt></tag>
2303 Allow labels without a trailing colon. These labels are only accepted,
2304 if they start at the beginning of a line (no leading white space).
2306 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2308 Accept the dot (`.') as the first character of an identifier. This may be
2309 used for example to create macro names that start with a dot emulating
2310 control directives of other assemblers. Note however, that none of the
2311 reserved keywords built into the assembler, that starts with a dot, may be
2312 overridden. When using this feature, you may also get into trouble if
2313 later versions of the assembler define new keywords starting with a dot.
2315 <tag><tt>loose_char_term</tt></tag>
2317 Accept single quotes as well as double quotes as terminators for char
2320 <tag><tt>loose_string_term</tt></tag>
2322 Accept single quotes as well as double quotes as terminators for string
2325 <tag><tt>missing_char_term</tt></tag>
2327 Accept single quoted character constants where the terminating quote is
2332 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2333 loose_string_term/, since in this case the input would be ambiguous.
2335 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2337 This feature makes relocatable/absolute mode local to the current segment.
2338 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2339 effect will only enable absolute mode for the current segment. Dito for
2340 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2342 <tag><tt>pc_assignment</tt></tag>
2344 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2345 is enabled). Such an assignment is handled identical to the <tt><ref
2346 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2347 removing the lines with the assignments may also be an option when porting
2348 code written for older assemblers).
2350 <tag><tt>ubiquitous_idents</tt></tag>
2352 Allow the use of instructions names as names for macros and symbols. This
2353 makes it possible to "overload" instructions by defining a macro with the
2354 same name. This does also make it possible to introduce hard to find errors
2355 in your code, so be careful!
2359 It is also possible to specify features on the command line using the
2360 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2361 This is useful when translating sources written for older assemblers, when
2362 you don't want to change the source code.
2364 As an example, to translate sources written for Andre Fachats xa65
2365 assembler, the features
2368 labels_without_colons, pc_assignment, loose_char_term
2371 may be helpful. They do not make ca65 completely compatible, so you may not
2372 be able to translate the sources without changes, even when enabling these
2373 features. However, I have found several sources that translate without
2374 problems when enabling these features on the command line.
2377 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2379 Insert an option string into the object file. There are two forms of
2380 this command, one specifies the option by a keyword, the second
2381 specifies it as a number. Since usage of the second one needs knowledge
2382 of the internal encoding, its use is not recommended and I will only
2383 describe the first form here.
2385 The command is followed by one of the keywords
2393 a comma and a string. The option is written into the object file
2394 together with the string value. This is currently unidirectional and
2395 there is no way to actually use these options once they are in the
2401 .fileopt comment, "Code stolen from my brother"
2402 .fileopt compiler, "BASIC 2.0"
2403 .fopt author, "J. R. User"
2407 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2409 Import an absolute symbol from another module. The command is followed by a
2410 comma separated list of symbols to import. The command is similar to <tt>
2411 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2412 written to the generated object file, even if the symbol is never referenced
2413 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2414 references for unused symbols).
2419 .forceimport needthisone, needthistoo
2422 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2425 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2427 Declare symbols as global. Must be followed by a comma separated list of
2428 symbols to declare. Symbols from the list, that are defined somewhere in the
2429 source, are exported, all others are imported. Additional <tt><ref
2430 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2431 name=".EXPORT"></tt> commands for the same symbol are allowed.
2440 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2442 Declare symbols as global. Must be followed by a comma separated list of
2443 symbols to declare. Symbols from the list, that are defined somewhere in the
2444 source, are exported, all others are imported. Additional <tt><ref
2445 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2446 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2447 in the list are explicitly marked as zero page symbols.
2455 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2457 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2458 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2459 the operator '>' prepended to each expression in its list.
2464 .lobytes $1234, $2345, $3456, $4567
2465 .hibytes $fedc, $edcb, $dcba, $cba9
2468 which is equivalent to
2471 .byte $34, $45, $56, $67
2472 .byte $fe, $ed, $dc, $cb
2478 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2480 TableLookupLo: .lobytes MyTable
2481 TableLookupHi: .hibytes MyTable
2484 which is equivalent to
2487 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2488 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2491 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2492 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2493 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2496 <sect1><tt>.I16</tt><label id=".I16"><p>
2498 Valid only in 65816 mode. Switch the index registers to 16 bit.
2500 Note: This command will not emit any code, it will tell the assembler to
2501 create 16 bit operands for immediate operands.
2503 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2504 name=".SMART"></tt> commands.
2507 <sect1><tt>.I8</tt><label id=".I8"><p>
2509 Valid only in 65816 mode. Switch the index registers to 8 bit.
2511 Note: This command will not emit any code, it will tell the assembler to
2512 create 8 bit operands for immediate operands.
2514 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2515 name=".SMART"></tt> commands.
2518 <sect1><tt>.IF</tt><label id=".IF"><p>
2520 Conditional assembly: Evaluate an expression and switch assembler output
2521 on or off depending on the expression. The expression must be a constant
2522 expression, that is, all operands must be defined.
2524 A expression value of zero evaluates to FALSE, any other value evaluates
2528 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2530 Conditional assembly: Check if there are any remaining tokens in this line,
2531 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2532 condition is not true, further lines are not assembled until an <tt><ref
2533 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2534 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2536 This command is often used to check if a macro parameter was given. Since an
2537 empty macro parameter will evaluate to nothing, the condition will evaluate
2538 to FALSE if an empty parameter was given.
2552 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2555 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2557 Conditional assembly: Evaluate an expression and switch assembler output
2558 on or off depending on the constness of the expression.
2560 A const expression evaluates to to TRUE, a non const expression (one
2561 containing an imported or currently undefined symbol) evaluates to
2564 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2567 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2569 Conditional assembly: Check if a symbol is defined. Must be followed by
2570 a symbol name. The condition is true if the the given symbol is already
2571 defined, and false otherwise.
2573 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2576 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2578 Conditional assembly: Check if there are any remaining tokens in this line,
2579 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2580 condition is not true, further lines are not assembled until an <tt><ref
2581 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2582 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2584 This command is often used to check if a macro parameter was given.
2585 Since an empty macro parameter will evaluate to nothing, the condition
2586 will evaluate to FALSE if an empty parameter was given.
2599 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2602 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2604 Conditional assembly: Check if a symbol is defined. Must be followed by
2605 a symbol name. The condition is true if the the given symbol is not
2606 defined, and false otherwise.
2608 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2611 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2613 Conditional assembly: Check if a symbol is referenced. Must be followed
2614 by a symbol name. The condition is true if if the the given symbol was
2615 not referenced before, and false otherwise.
2617 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2620 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2622 Conditional assembly: Check if the assembler is currently in 6502 mode
2623 (see <tt><ref id=".P02" name=".P02"></tt> command).
2626 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2628 Conditional assembly: Check if the assembler is currently in 65816 mode
2629 (see <tt><ref id=".P816" name=".P816"></tt> command).
2632 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2634 Conditional assembly: Check if the assembler is currently in 65C02 mode
2635 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2638 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2640 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2641 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2644 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2646 Conditional assembly: Check if a symbol is referenced. Must be followed
2647 by a symbol name. The condition is true if if the the given symbol was
2648 referenced before, and false otherwise.
2650 This command may be used to build subroutine libraries in include files
2651 (you may use separate object modules for this purpose too).
2656 .ifref ToHex ; If someone used this subroutine
2657 ToHex: tay ; Define subroutine
2663 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2666 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2668 Import a symbol from another module. The command is followed by a comma
2669 separated list of symbols to import, with each one optionally followed by
2670 an address specification.
2676 .import bar: zeropage
2679 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2682 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2684 Import a symbol from another module. The command is followed by a comma
2685 separated list of symbols to import. The symbols are explicitly imported
2686 as zero page symbols (that is, symbols with values in byte range).
2694 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2697 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2699 Include a file as binary data. The command expects a string argument
2700 that is the name of a file to include literally in the current segment.
2701 In addition to that, a start offset and a size value may be specified,
2702 separated by commas. If no size is specified, all of the file from the
2703 start offset to end-of-file is used. If no start position is specified
2704 either, zero is assumed (which means that the whole file is inserted).
2709 ; Include whole file
2710 .incbin "sprites.dat"
2712 ; Include file starting at offset 256
2713 .incbin "music.dat", $100
2715 ; Read 100 bytes starting at offset 200
2716 .incbin "graphics.dat", 200, 100
2720 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2722 Include another file. Include files may be nested up to a depth of 16.
2731 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
2733 Export a symbol and mark it as an interruptor. This may be used together
2734 with the linker to build a table of interruptor subroutines that are called
2737 Note: The linker has a feature to build a table of marked routines, but it
2738 is your code that must call these routines, so just declaring a symbol as
2739 interruptor does nothing by itself.
2741 An interruptor is always exported as an absolute (16 bit) symbol. You don't
2742 need to use an additional <tt/.export/ statement, this is implied by
2743 <tt/.interruptor/. It may have an optional priority that is separated by a
2744 comma. Higher numeric values mean a higher priority. If no priority is
2745 given, the default priority of 7 is used. Be careful when assigning
2746 priorities to your own module constructors so they won't interfere with the
2747 ones in the cc65 library.
2752 .interruptor IrqHandler
2753 .interruptor Handler, 16
2756 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
2757 section <ref id="condes" name="Module constructors/destructors"> explaining
2758 the feature in more detail.
2761 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2763 Switch on or off line continuations using the backslash character
2764 before a newline. The option is off by default.
2765 Note: Line continuations do not work in a comment. A backslash at the
2766 end of a comment is treated as part of the comment and does not trigger
2768 The command must be followed by a '+' or '-' character to switch the
2769 option on or off respectively.
2774 .linecont + ; Allow line continuations
2777 #$20 ; This is legal now
2781 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2783 Enable output to the listing. The command must be followed by a boolean
2784 switch ("on", "off", "+" or "-") and will enable or disable listing
2786 The option has no effect if the listing is not enabled by the command line
2787 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2788 to the listing file, if the counter is greater than zero, and suppressed if
2789 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2795 .list on ; Enable listing output
2799 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2801 Set, how many bytes are shown in the listing for one source line. The
2802 default is 12, so the listing will show only the first 12 bytes for any
2803 source line that generates more than 12 bytes of code or data.
2804 The directive needs an argument, which is either "unlimited", or an
2805 integer constant in the range 4..255.
2810 .listbytes unlimited ; List all bytes
2811 .listbytes 12 ; List the first 12 bytes
2812 .incbin "data.bin" ; Include large binary file
2816 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
2818 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
2819 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2820 the operator '<' prepended to each expression in its list.
2825 .lobytes $1234, $2345, $3456, $4567
2826 .hibytes $fedc, $edcb, $dcba, $cba9
2829 which is equivalent to
2832 .byte $34, $45, $56, $67
2833 .byte $fe, $ed, $dc, $cb
2839 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2841 TableLookupLo: .lobytes MyTable
2842 TableLookupHi: .hibytes MyTable
2845 which is equivalent to
2848 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2849 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2852 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2853 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2854 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2857 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2859 This command may only be used inside a macro definition. It declares a
2860 list of identifiers as local to the macro expansion.
2862 A problem when using macros are labels: Since they don't change their name,
2863 you get a "duplicate symbol" error if the macro is expanded the second time.
2864 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2865 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2868 Some other assemblers start a new lexical block inside a macro expansion.
2869 This has some drawbacks however, since that will not allow <em/any/ symbol
2870 to be visible outside a macro, a feature that is sometimes useful. The
2871 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2872 to address the problem.
2874 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2878 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2880 Defines the character that start "cheap" local labels. You may use one
2881 of '@' and '?' as start character. The default is '@'.
2883 Cheap local labels are labels that are visible only between two non
2884 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2885 using explicit lexical nesting.
2892 Clear: lda #$00 ; Global label
2893 ?Loop: sta Mem,y ; Local label
2897 Sub: ... ; New global label
2898 bne ?Loop ; ERROR: Unknown identifier!
2902 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2904 Insert a predefined macro package. The command is followed by an
2905 identifier specifying the macro package to insert. Available macro
2909 atari Defines the scrcode macro.
2910 cbm Defines the scrcode macro.
2911 cpu Defines constants for the .CPU variable.
2912 generic Defines generic macros like add and sub.
2913 longbranch Defines conditional long jump macros.
2916 Including a macro package twice, or including a macro package that
2917 redefines already existing macros will lead to an error.
2922 .macpack longbranch ; Include macro package
2924 cmp #$20 ; Set condition codes
2925 jne Label ; Jump long on condition
2928 Macro packages are explained in more detail in section <ref
2929 id="macropackages" name="Macro packages">.
2932 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2934 Start a classic macro definition. The command is followed by an identifier
2935 (the macro name) and optionally by a comma separated list of identifiers
2936 that are macro parameters.
2938 See section <ref id="macros" name="Macros">.
2941 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2943 Start a section of absolute code. The command is followed by a constant
2944 expression that gives the new PC counter location for which the code is
2945 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2948 By default, absolute/relocatable mode is global (valid even when switching
2949 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
2950 it can be made segment local.
2952 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
2953 code at a specific address is the job of the linker, not the assembler, so
2954 there is usually no reason to assemble code to a specific address.
2959 .org $7FF ; Emit code starting at $7FF
2963 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2965 Output a string to the console without producing an error. This command
2966 is similar to <tt/.ERROR/, however, it does not force an assembler error
2967 that prevents the creation of an object file.
2972 .out "This code was written by the codebuster(tm)"
2975 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2976 id=".ERROR" name=".ERROR"></tt> directives.
2979 <sect1><tt>.P02</tt><label id=".P02"><p>
2981 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
2982 instructions. This is the default if not overridden by the
2983 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
2985 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
2986 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2989 <sect1><tt>.P816</tt><label id=".P816"><p>
2991 Enable the 65816 instruction set. This is a superset of the 65SC02 and
2992 6502 instruction sets.
2994 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2995 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
2998 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3000 Set the page length for the listing. Must be followed by an integer
3001 constant. The value may be "unlimited", or in the range 32 to 127. The
3002 statement has no effect if no listing is generated. The default value is -1
3003 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3004 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3005 after assembly is complete, you cannot use multiple line lengths with one
3006 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3011 .pagelength 66 ; Use 66 lines per listing page
3013 .pagelength unlimited ; Unlimited page length
3017 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3019 Enable the 65C02 instructions set. This instruction set includes all
3020 6502 and 65SC02 instructions.
3022 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3023 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3026 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3028 Pop the last pushed segment from the stack, and set it.
3030 This command will switch back to the segment that was last pushed onto the
3031 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3032 command, and remove this entry from the stack.
3034 The assembler will print an error message if the segment stack is empty
3035 when this command is issued.
3037 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3040 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3042 Start a nested lexical level with the given name and adds a symbol with this
3043 name to the enclosing scope. All new symbols from now on are in the local
3044 lexical level and are accessible from outside only via <ref id="scopesyntax"
3045 name="explicit scope specification">. Symbols defined outside this local
3046 level may be accessed as long as their names are not used for new symbols
3047 inside the level. Symbols names in other lexical levels do not clash, so you
3048 may use the same names for identifiers. The lexical level ends when the
3049 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3050 may be nested up to a depth of 16 (this is an artificial limit to protect
3051 against errors in the source).
3053 Note: Macro names are always in the global level and in a separate name
3054 space. There is no special reason for this, it's just that I've never
3055 had any need for local macro definitions.
3060 .proc Clear ; Define Clear subroutine, start new level
3062 L1: sta Mem,y ; L1 is local and does not cause a
3063 ; duplicate symbol error if used in other
3066 bne L1 ; Reference local symbol
3068 .endproc ; Leave lexical level
3071 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3075 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3077 Enable the 65SC02 instructions set. This instruction set includes all
3080 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3081 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3084 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3086 Push the currently active segment onto a stack. The entries on the stack
3087 include the name of the segment and the segment type. The stack has a size
3090 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3091 to switch to another segment and to restore the old segment later, without
3092 even knowing the name and type of the current segment.
3094 The assembler will print an error message if the segment stack is already
3095 full, when this command is issued.
3097 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3100 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3102 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3103 name=".ORG"></tt> command.
3106 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3108 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3109 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3110 a constant expression that tells how many times the commands in the body
3111 should get repeated. Optionally, a comma and an identifier may be specified.
3112 If this identifier is found in the body of the repeat statement, it is
3113 replaced by the current repeat count (starting with zero for the first time
3114 the body is repeated).
3116 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3117 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3118 level will be used, not the one from the outer level.
3122 The following macro will emit a string that is "encrypted" in that all
3123 characters of the string are XORed by the value $55.
3127 .repeat .strlen(Arg), I
3128 .byte .strat(Arg, I) ^ $55
3133 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3136 <sect1><tt>.RES</tt><label id=".RES"><p>
3138 Reserve storage. The command is followed by one or two constant
3139 expressions. The first one is mandatory and defines, how many bytes of
3140 storage should be defined. The second, optional expression must by a
3141 constant byte value that will be used as value of the data. If there
3142 is no fill value given, the linker will use the value defined in the
3143 linker configuration file (default: zero).
3148 ; Reserve 12 bytes of memory with value $AA
3153 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3155 Switch to the RODATA segment. The name of the RODATA segment is always
3156 "RODATA", so this is a shortcut for
3162 The RODATA segment is a segment that is used by the compiler for
3163 readonly data like string constants.
3165 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3168 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3170 Start a nested lexical level with the given name. All new symbols from now
3171 on are in the local lexical level and are accessible from outside only via
3172 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3173 outside this local level may be accessed as long as their names are not used
3174 for new symbols inside the level. Symbols names in other lexical levels do
3175 not clash, so you may use the same names for identifiers. The lexical level
3176 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3177 read. Lexical levels may be nested up to a depth of 16 (this is an
3178 artificial limit to protect against errors in the source).
3180 Note: Macro names are always in the global level and in a separate name
3181 space. There is no special reason for this, it's just that I've never
3182 had any need for local macro definitions.
3187 .scope Error ; Start new scope named Error
3189 File = 1 ; File error
3190 Parse = 2 ; Parse error
3191 .endscope ; Close lexical level
3194 lda #Error::File ; Use symbol from scope Error
3197 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3201 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3203 Switch to another segment. Code and data is always emitted into a
3204 segment, that is, a named section of data. The default segment is
3205 "CODE". There may be up to 254 different segments per object file
3206 (and up to 65534 per executable). There are shortcut commands for
3207 the most common segments ("CODE", "DATA" and "BSS").
3209 The command is followed by a string containing the segment name (there are
3210 some constraints for the name - as a rule of thumb use only those segment
3211 names that would also be valid identifiers). There may also be an optional
3212 address size separated by a colon. See the section covering <tt/<ref
3213 id="address-sizes" name="address sizes">/ for more information.
3215 The default address size for a segment depends on the memory model specified
3216 on the command line. The default is "absolute", which means that you don't
3217 have to use an address size modifier in most cases.
3219 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3220 That is, the segment will reside somewhere in core memory outside the zero
3221 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3222 page and direct (short) addressing is possible for data in this segment.
3224 Beware: Only labels in a segment with the zeropage attribute are marked
3225 as reachable by short addressing. The `*' (PC counter) operator will
3226 work as in other segments and will create absolute variable values.
3228 Please note that a segment cannot have two different address sizes. A
3229 segment specified as zeropage cannot be declared as being absolute later.
3234 .segment "ROM2" ; Switch to ROM2 segment
3235 .segment "ZP2": zeropage ; New direct segment
3236 .segment "ZP2" ; Ok, will use last attribute
3237 .segment "ZP2": absolute ; Error, redecl mismatch
3240 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3241 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3242 id=".RODATA" name=".RODATA"></tt>
3245 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3247 Switch the CPU instruction set. The command is followed by a string that
3248 specifies the CPU. Possible values are those that can also be supplied to
3249 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3250 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3251 note that support for the sunplus CPU is not available in the freeware
3252 version, because the instruction set of the sunplus CPU is "proprietary
3255 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3256 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3257 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3258 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3259 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3260 <tt><ref id=".P02" name=".P02"></tt>,
3261 <tt><ref id=".P816" name=".P816"></tt>,
3262 <tt><ref id=".PC02" name=".PC02"></tt>,
3263 <tt><ref id=".PSC02" name=".PSC02"></tt>
3266 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3268 Switch on or off smart mode. The command must be followed by a '+' or '-'
3269 character to switch the option on or off respectively. The default is off
3270 (that is, the assembler doesn't try to be smart), but this default may be
3271 changed by the -s switch on the command line.
3273 In smart mode the assembler will do the following:
3276 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3277 and update the operand sizes accordingly. If the operand of such an
3278 instruction cannot be evaluated by the assembler (for example, because
3279 the operand is an imported symbol), a warning is issued. Beware: Since
3280 the assembler cannot trace the execution flow this may lead to false
3281 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3282 instructions to tell the assembler about the current settings.
3283 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3284 used within a procedure declared as <tt/far/, or if the procedure has
3285 no explicit address specification, but it is <tt/far/ because of the
3293 .smart - ; Stop being smart
3296 See: <tt><ref id=".A16" name=".A16"></tt>,
3297 <tt><ref id=".A8" name=".A8"></tt>,
3298 <tt><ref id=".I16" name=".I16"></tt>,
3299 <tt><ref id=".I8" name=".I8"></tt>
3302 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3304 Starts a struct definition. Structs are covered in a separate section named
3305 <ref id="structs" name=""Structs and unions"">.
3307 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3310 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3312 Enable the SunPlus instructions set. This command will not work in the
3313 freeware version of the assembler, because the instruction set is
3314 "proprietary and confidential".
3316 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3317 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3318 <tt><ref id=".P816" name=".P816"></tt>
3321 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3323 Allocate space for a struct or union.
3334 .tag Point ; Allocate 4 bytes
3338 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3340 Force an assembly warning. The assembler will output a warning message
3341 preceded by "User warning". This warning will always be output, even if
3342 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3343 command line option.
3345 This command may be used to output possible problems when assembling
3354 .warning "Forward jump in jne, cannot optimize!"
3364 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
3365 name=".OUT"></tt> directives.
3368 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3370 Define word sized data. Must be followed by a sequence of (word ranged,
3371 but not necessarily constant) expressions.
3376 .word $0D00, $AF13, _Clear
3380 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3382 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3383 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3387 .segment "ZEROPAGE", zeropage
3390 Because of the "zeropage" attribute, labels declared in this segment are
3391 addressed using direct addressing mode if possible. You <em/must/ instruct
3392 the linker to place this segment somewhere in the address range 0..$FF
3393 otherwise you will get errors.
3395 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3399 <sect>Macros<label id="macros"><p>
3402 <sect1>Introduction<p>
3404 Macros may be thought of as "parametrized super instructions". Macros are
3405 sequences of tokens that have a name. If that name is used in the source
3406 file, the macro is "expanded", that is, it is replaced by the tokens that
3407 were specified when the macro was defined.
3410 <sect1>Macros without parameters<p>
3412 In it's simplest form, a macro does not have parameters. Here's an
3416 .macro asr ; Arithmetic shift right
3417 cmp #$80 ; Put bit 7 into carry
3418 ror ; Rotate right with carry
3422 The macro above consists of two real instructions, that are inserted into
3423 the code, whenever the macro is expanded. Macro expansion is simply done
3424 by using the name, like this:
3433 <sect1>Parametrized macros<p>
3435 When using macro parameters, macros can be even more useful:
3449 When calling the macro, you may give a parameter, and each occurrence of
3450 the name "addr" in the macro definition will be replaced by the given
3469 A macro may have more than one parameter, in this case, the parameters
3470 are separated by commas. You are free to give less parameters than the
3471 macro actually takes in the definition. You may also leave intermediate
3472 parameters empty. Empty parameters are replaced by empty space (that is,
3473 they are removed when the macro is expanded). If you have a look at our
3474 macro definition above, you will see, that replacing the "addr" parameter
3475 by nothing will lead to wrong code in most lines. To help you, writing
3476 macros with a variable parameter list, there are some control commands:
3478 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3479 returns true, if there are any tokens on the remainder of the line. Since
3480 empty parameters are replaced by nothing, this may be used to test if a given
3481 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3484 Look at this example:
3487 .macro ldaxy a, x, y
3500 This macro may be called as follows:
3503 ldaxy 1, 2, 3 ; Load all three registers
3505 ldaxy 1, , 3 ; Load only a and y
3507 ldaxy , , 3 ; Load y only
3510 There's another helper command for determining, which macro parameters are
3511 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3512 replaced by the parameter count given, <em/including/ intermediate empty macro
3516 ldaxy 1 ; .PARAMCOUNT = 1
3517 ldaxy 1,,3 ; .PARAMCOUNT = 3
3518 ldaxy 1,2 ; .PARAMCOUNT = 2
3519 ldaxy 1, ; .PARAMCOUNT = 2
3520 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3523 Macro parameters may optionally be enclosed into curly braces. This allows the
3524 inclusion of tokens that would otherwise terminate the parameter (the comma in
3525 case of a macro parameter).
3528 .macro foo arg1, arg2
3532 foo ($00,x) ; Two parameters passed
3533 foo {($00,x)} ; One parameter passed
3536 In the first case, the macro is called with two parameters: '<tt/($00/'
3537 and 'x)'. The comma is not passed to the macro, since it is part of the
3538 calling sequence, not the parameters.
3540 In the second case, '($00,x)' is passed to the macro, this time
3541 including the comma.
3544 <sect1>Detecting parameter types<p>
3546 Sometimes it is nice to write a macro that acts differently depending on the
3547 type of the argument supplied. An example would be a macro that loads a 16 bit
3548 value from either an immediate operand, or from memory. The <tt/<ref
3549 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3550 functions will allow you to do exactly this:
3554 .if (.match (.left (1, {arg}), #))
3556 lda #<(.right (.tcount ({arg})-1, {arg}))
3557 ldx #>(.right (.tcount ({arg})-1, {arg}))
3559 ; assume absolute or zero page
3566 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3567 check if its argument begins with a hash mark. If so, two immediate loads are
3568 emitted, Otherwise a load from an absolute zero page memory location is
3569 assumed. Please note how the curly braces are used to enclose parameters to
3570 pseudo functions handling token lists. This is necessary, because the token
3571 lists may include commas or parens, which would be treated by the assembler
3574 The macro can be used as
3579 ldax #$1234 ; X=$12, A=$34
3581 ldax foo ; X=$56, A=$78
3585 <sect1>Recursive macros<p>
3587 Macros may be used recursively:
3590 .macro push r1, r2, r3
3599 There's also a special macro to help writing recursive macros: <tt><ref
3600 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3604 .macro push r1, r2, r3, r4, r5, r6, r7
3606 ; First parameter is empty
3612 push r2, r3, r4, r5, r6, r7
3616 When expanding this macro, the expansion will push all given parameters
3617 until an empty one is encountered. The macro may be called like this:
3620 push $20, $21, $32 ; Push 3 ZP locations
3621 push $21 ; Push one ZP location
3625 <sect1>Local symbols inside macros<p>
3627 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3628 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3629 Have a look at the inc16 macro above. Here is it again:
3643 If you have a closer look at the code, you will notice, that it could be
3644 written more efficiently, like this:
3655 But imagine what happens, if you use this macro twice? Since the label
3656 "Skip" has the same name both times, you get a "duplicate symbol" error.
3657 Without a way to circumvent this problem, macros are not as useful, as
3658 they could be. One solution is, to start a new lexical block inside the
3672 Now the label is local to the block and not visible outside. However,
3673 sometimes you want a label inside the macro to be visible outside. To make
3674 that possible, there's a new command that's only usable inside a macro
3675 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3676 or more symbols as local to the macro expansion. The names of local variables
3677 are replaced by a unique name in each separate macro expansion. So we could
3678 also solve the problem above by using <tt/.LOCAL/:
3682 .local Skip ; Make Skip a local symbol
3689 Skip: ; Not visible outside
3694 <sect1>C style macros<p>
3696 Starting with version 2.5 of the assembler, there is a second macro type
3697 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3698 similar to the classic macro type described above, but behaviour is sometimes
3703 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3704 span more than a line. You may use line continuation (see <tt><ref
3705 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3706 more than one line for increased readability, but the macro itself
3707 may not contain an end-of-line token.
3709 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3710 the name space with classic macros, but they are detected and replaced
3711 at the scanner level. While classic macros may be used in every place,
3712 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3713 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3714 they are more versatile in some situations.
3716 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3717 parameters. While classic macros may have empty parameters, this is
3718 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3719 For this macro type, the number of actual parameters must match
3720 exactly the number of formal parameters.
3722 To make this possible, formal parameters are enclosed in braces when
3723 defining the macro. If there are no parameters, the empty braces may
3726 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3727 contain end-of-line tokens, there are things that cannot be done. They
3728 may not contain several processor instructions for example. So, while
3729 some things may be done with both macro types, each type has special
3730 usages. The types complement each other.
3734 Let's look at a few examples to make the advantages and disadvantages
3737 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3738 following <tt/.DEFINE/:
3743 foo EQU $1234 ; This is accepted now
3746 You may use the directive to define string constants used elsewhere:
3749 ; Define the version number
3750 .define VERSION "12.3a"
3756 Macros with parameters may also be useful:
3759 .define DEBUG(message) .out message
3761 DEBUG "Assembling include file #3"
3764 Note that, while formal parameters have to be placed in braces, this is
3765 not true for the actual parameters. Beware: Since the assembler cannot
3766 detect the end of one parameter, only the first token is used. If you
3767 don't like that, use classic macros instead:
3775 (This is an example where a problem can be solved with both macro types).
3778 <sect1>Characters in macros<p>
3780 When using the <ref id="option-t" name="-t"> option, characters are translated
3781 into the target character set of the specific machine. However, this happens
3782 as late as possible. This means that strings are translated if they are part
3783 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3784 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3785 used as part of an expression.
3787 This behaviour is very intuitive outside of macros but may be confusing when
3788 doing more complex macros. If you compare characters against numeric values,
3789 be sure to take the translation into account.
3794 <sect>Macro packages<label id="macropackages"><p>
3796 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3797 macro packages may be included with just one command. Available macro packages
3801 <sect1><tt>.MACPACK generic</tt><p>
3803 This macro package defines macros that are useful in almost any program.
3804 Currently, two macros are defined:
3819 <sect1><tt>.MACPACK longbranch</tt><p>
3821 This macro package defines long conditional jumps. They are named like the
3822 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3823 definition for the "<tt/jeq/" macro, the other macros are built using the same
3828 .if .def(Target) .and ((*+2)-(Target) <= 127)
3837 All macros expand to a short branch, if the label is already defined (back
3838 jump) and is reachable with a short jump. Otherwise the macro expands to a
3839 conditional branch with the branch condition inverted, followed by an absolute
3840 jump to the actual branch target.
3842 The package defines the following macros:
3845 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3850 <sect1><tt>.MACPACK cbm</tt><p>
3852 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3853 string as argument and places this string into memory translated into screen
3857 <sect1><tt>.MACPACK cpu</tt><p>
3859 This macro package does not define any macros but constants used to examine
3860 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3861 each supported CPU a constant similar to
3873 is defined. These constants may be used to determine the exact type of the
3874 currently enabled CPU. In addition to that, for each CPU instruction set,
3875 another constant is defined:
3887 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3888 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3889 currently enabled CPU supports a specific instruction set. For example the
3890 65C02 supports all instructions of the 65SC02 CPU, so it has the
3891 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3895 .if (.cpu .bitand CPU_ISET_65SC02)
3903 it is possible to determine if the
3909 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3910 CPUs (the latter two are upwards compatible to the 65SC02).
3914 <sect>Predefined constants<label id="predefined-constants"><p>
3916 For better orthogonality, the assembler defines similar symbols as the
3917 compiler, depending on the target system selected:
3920 <item><tt/__APPLE2__/ - Target system is <tt/apple2/
3921 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
3922 <item><tt/__ATARI__/ - Target system is <tt/atari/
3923 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
3924 <item><tt/__BBC__/ - Target system is <tt/bbc/
3925 <item><tt/__C128__/ - Target system is <tt/c128/
3926 <item><tt/__C16__/ - Target system is <tt/c16/
3927 <item><tt/__C64__/ - Target system is <tt/c64/
3928 <item><tt/__CBM__/ - Target is a Commodore system
3929 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
3930 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
3931 <item><tt/__GEOS__/ - Target system is <tt/geos/
3932 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
3933 <item><tt/__NES__/ - Target system is <tt/nes/
3934 <item><tt/__PET__/ - Target system is <tt/pet/
3935 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
3936 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
3937 <item><tt/__VIC20__/ - Target system is <tt/vic20/
3941 <sect>Structs and unions<label id="structs"><p>
3943 <sect1>Structs and unions Overview<p>
3945 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3946 are to some degree comparable to their C counterparts. Both have a list of
3947 members. Each member allocates storage and may optionally have a name, which,
3948 in case of a struct, is the offset from the beginning and, in case of a union,
3952 <sect1>Declaration<p>
3954 Here is an example for a very simple struct with two members and a total size
3964 A union shares the total space between all its members, its size is the same
3965 as that of the largest member.
3967 A struct or union must not necessarily have a name. If it is anonymous, no
3968 local scope is opened, the identifiers used to name the members are placed
3969 into the current scope instead.
3971 A struct may contain unnamed members and definitions of local structs. The
3972 storage allocators may contain a multiplier, as in the example below:
3977 .word 2 ; Allocate two words
3984 <sect1>The <tt/.TAG/ keyword<p>
3986 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
3987 for an already defined struct or unions within another struct:
4001 Space for a struct or union may be allocated using the <ref id=".TAG"
4002 name=".TAG"> directive.
4008 Currently, members are just offsets from the start of the struct or union. To
4009 access a field of a struct, the member offset has to be added to the address
4010 of the struct itself:
4013 lda C+Circle::Radius ; Load circle radius into A
4016 This may change in a future version of the assembler.
4019 <sect1>Limitations<p>
4021 Structs and unions are currently implemented as nested symbol tables (in fact,
4022 they were a by-product of the improved scoping rules). Currently, the
4023 assembler has no idea of types. This means that the <ref id=".TAG"
4024 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4025 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4026 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4027 this structure accessible by using the '::' operator.
4031 <sect>Module constructors/destructors<label id="condes"><p>
4033 <em>Note:</em> This section applies mostly to C programs, so the explanation
4034 below uses examples from the C libraries. However, the feature may also be
4035 useful for assembler programs.
4038 <sect1>Module constructors/destructors Overview<p>
4040 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4041 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4042 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
4043 special way. The linker is able to generate tables with all functions of a
4044 specific type. Such a table will <em>only</em> include symbols from object
4045 files that are linked into a specific executable. This may be used to add
4046 initialization and cleanup code for library modules, or a table of interrupt
4049 The C heap functions are an example where module initialization code is used.
4050 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4051 variables that contain the start and the end of the heap, pointers to the free
4052 list and so on. Since the end of the heap depends on the size and start of the
4053 stack, it must be initialized at runtime. However, initializing these
4054 variables for programs that do not use the heap are a waste of time and
4057 So the central module defines a function that contains initialization code and
4058 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4059 this module is added to an executable by the linker, the initialization
4060 function will be placed into the table of constructors by the linker. The C
4061 startup code will call all constructors before <tt/main/ and all destructors
4062 after <tt/main/, so without any further work, the heap initialization code is
4063 called once the module is linked in.
4065 While it would be possible to add explicit calls to initialization functions
4066 in the startup code, the new approach has several advantages:
4070 If a module is not included, the initialization code is not linked in and not
4071 called. So you don't pay for things you don't need.
4074 Adding another library that needs initialization does not mean that the
4075 startup code has to be changed. Before we had module constructors and
4076 destructors, the startup code for all systems had to be adjusted to call the
4077 new initialization code.
4080 The feature saves memory: Each additional initialization function needs just
4081 two bytes in the table (a pointer to the function).
4086 <sect1>Calling order<p>
4088 The symbols are sorted in increasing priority order by the linker when using
4089 one of the builtin linker configurations, so the functions with lower
4090 priorities come first and are followed by those with higher priorities. The C
4091 library runtime subroutine that walks over the function tables calls the
4092 functions starting from the top of the table - which means that functions with
4093 a high priority are called first.
4095 So when using the C runtime, functions are called with high priority functions
4096 first, followed by low priority functions.
4101 When using these special symbols, please take care of the following:
4106 The linker will only generate function tables, it will not generate code to
4107 call these functions. If you're using the feature in some other than the
4108 existing C environments, you have to write code to call all functions in a
4109 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4110 in the C runtime for an example on how to do this.
4113 The linker will only add addresses of functions that are in modules linked to
4114 the executable. This means that you have to be careful where to place the
4115 condes functions. If initialization or an irq handler is needed for a group of
4116 functions, be sure to place the function into a module that is linked in
4117 regardless of which function is called by the user.
4120 The linker will generate the tables only when requested to do so by the
4121 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4122 be requested separately.
4125 Constructors and destructors may have priorities. These priorities determine
4126 the order of the functions in the table. If your initialization or cleanup code
4127 does depend on other initialization or cleanup code, you have to choose the
4128 priority for the functions accordingly.
4131 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4132 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4133 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4134 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4135 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4136 (interruptor). The linker generates a separate table for each type on request.
4141 <sect>Porting sources from other assemblers<p>
4143 Sometimes it is necessary to port code written for older assemblers to ca65.
4144 In some cases, this can be done without any changes to the source code by
4145 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4146 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4149 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4150 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4151 done by the linker. Most other assemblers generate absolute code, placement is
4152 done within the assembler and there is no external linker.
4154 In general it is not a good idea to write new code using the emulation
4155 features of the assembler, but there may be situations where even this rule is
4160 You need to use some of the ca65 emulation features to simulate the behaviour
4161 of such simple assemblers.
4164 <item>Prepare your sourcecode like this:
4167 ; if you want TASS style labels without colons
4168 .feature labels_without_colons
4170 ; if you want TASS style character constants
4171 ; ("a" instead of the default 'a')
4172 .feature loose_char_term
4174 .word *+2 ; the cbm load address
4179 notice that the two emulation features are mostly useful for porting
4180 sources originally written in/for TASS, they are not needed for the
4181 actual "simple assembler operation" and are not recommended if you are
4182 writing new code from scratch.
4184 <item>Replace all program counter assignments (which are not possible in ca65
4185 by default, and the respective emulation feature works different from what
4186 you'd expect) by another way to skip to memory locations, for example the
4187 <tt><ref id=".RES" name=".RES"></tt> directive.
4191 .res $2000-* ; reserve memory up to $2000
4194 Please note that other than the original TASS, ca65 can never move the program
4195 counter backwards - think of it as if you are assembling to disk with TASS.
4197 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4198 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4199 of <tt/.goto/, everything involving loops must be replaced by
4200 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4202 <item>To assemble code to a different address than it is executed at, use the
4203 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4204 <tt/.offs/-constructs.
4211 .reloc ; back to normal
4214 <item>Then assemble like this:
4217 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4220 Note that you need to use the actual start address minus two, since two bytes
4221 are used for the cbm load address.
4226 <sect>Bugs/Feedback<p>
4228 If you have problems using the assembler, if you find any bugs, or if
4229 you're doing something interesting with the assembler, I would be glad to
4230 hear from you. Feel free to contact me by email
4231 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4237 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4238 Bassewitz. For usage of the binaries and/or sources the following
4239 conditions do apply:
4241 This software is provided 'as-is', without any expressed or implied
4242 warranty. In no event will the authors be held liable for any damages
4243 arising from the use of this software.
4245 Permission is granted to anyone to use this software for any purpose,
4246 including commercial applications, and to alter it and redistribute it
4247 freely, subject to the following restrictions:
4250 <item> The origin of this software must not be misrepresented; you must not
4251 claim that you wrote the original software. If you use this software
4252 in a product, an acknowledgment in the product documentation would be
4253 appreciated but is not required.
4254 <item> Altered source versions must be plainly marked as such, and must not
4255 be misrepresented as being the original software.
4256 <item> This notice may not be removed or altered from any source