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715 lines
28 KiB
HTML
715 lines
28 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<head>
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<title>xasm 2.6.1</title>
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<meta name="Author" content="Piotr Fusik"/>
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</head>
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<body>
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<h2>NAME</h2>
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<p>xasm - 6502 cross-assembler</p>
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<h2>SYNOPSIS</h2>
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<p><tt>xasm source [options]</tt></p>
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<h2>DESCRIPTION</h2>
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<p><b>xasm</b> is a cross-assembler which generates code for the 6502
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processor.</p>
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<p><tt>source</tt> is the name of the source file. If no filename extension
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is given, <tt>.ASX</tt> is appended. The default action (when invoked without
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options) is to assembly <tt>source</tt>, writing the result to a file with
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the <tt>.OBX</tt> extension.</p>
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<h2>OPTIONS</h2>
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<dl>
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<dt><tt>/c</tt></dt>
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<dd>Enable listing false conditionals.
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Lines skipped due to a false condition are not listed by default.</dd>
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<dt><a name="new_deflabel"/><tt>/d:label=value</tt></dt>
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<dd>Define a label.
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<tt>label</tt> should be a valid label name.
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<tt>value</tt> may be any expression (it may use forward references
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to labels defined in the source file).
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You may use several <tt>/d</tt> options to define many labels
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from the command line.</dd>
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<dt><a name="new_environment"/><tt>/e</tt></dt>
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<dd>Enable setting environment variables pointing at the error location.
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With this option, <b>xasm</b> sets two environment variables:
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<tt>ERRFILE</tt> and <tt>ERRLINE</tt>.
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They may be used in a batch file to locate the error and set editor's
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insertion point on it. If there was no error, the variables point at the last
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issued warning. If no warning occured, they are removed from
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the environment.</dd>
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<dt><tt>/i</tt></dt>
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<dd>Disable listing included sources. Only main source file will be
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listed.</dd>
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<dt><tt>/l[:filename]</tt></dt>
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<dd>Enable listing. If no <tt>filename</tt> is given, the listing is written
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to <tt>source.lst</tt>, where <tt>source</tt> is the name of the source file
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(without the extension).</dd>
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<dt><tt>/o:filename</tt></dt>
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<dd>Specify object file name. The default is <tt>source.obx</tt>.
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You may use the null device (<tt>/o:nul</tt>) to generate no object file.</dd>
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<dt><a name="new_fullpaths"/><tt>/p</tt></dt>
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<dd>Print fully qualified file names in listing and error messages.
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This option is useful for the Code-Genie editor, which can jump to the error
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location only if the full path is given.</dd>
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<dt><a name="new_quiet"/><tt>/q</tt></dt>
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<dd>Suppress info messages.
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Prevents <b>xasm</b> from printing its name and the summary (how many lines
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assembled and bytes written). Good if you are building a project from many
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source files and don't want tons of messages.</dd>
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<dt><tt>/t[:filename]</tt></dt>
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<dd>List label table. If no <tt>filename</tt> given, the table is appended
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to the listing.</dd>
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<dt><a name="new_unlabels"/><tt>/u</tt></dt>
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<dd>Warn of unused labels. A warning message will be issued for each label,
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whose value is never used.</dd>
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</dl>
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<h2>SYNTAX</h2>
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<p>Source files should be plain ASCII files. Although different line
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terminators are supported, CR/LF is recommended because it is the standard
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in the DOS/Windows environment. Lines must be no longer than 256
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characters. <b>xasm</b> is not case-sensitive, so you can mix upper-
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and lower-case for labels and instructions.</p>
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<p><b>xasm</b> is backward compatible with Quick Assembler.
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If you want to assembly QA sources with <b>xasm</b>, simply convert the text
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file to CR/LF terminators and replace ATASCII specific characters with their
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integer representation. You also have to change all <tt>OPT</tt> directives,
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but usually you only need to remove them.</p>
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<p>A <i>label</i> is a symbol that represents a 32-bit signed integer.
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You can define a label by putting its name at the beginning of a line
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(with no spaces before). If you do not use the <tt>EQU</tt> directive,
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the label is assigned the current value of the origin counter.</p>
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<p>Instructions and directives must be preceded with
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whitespace. Note that in <b>xasm</b> you can use instruction and directive
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names as label names. For example</p>
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<pre>nop
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</pre><p>defines a label called <tt>nop</tt>, whereas</p>
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<pre> nop
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</pre><p>is a 6502 instruction.</p>
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<p>Full comment lines must start with a semicolon, a pipe or an asterisk,
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with optional label definition and spaces before. Here are examples
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of full comment lines:</p>
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<pre>; this is a comment
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* so it is
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label | and this too
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</pre>
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<p><a name="new_linerep"/>Lines with instructions (and some directives)
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may be <i>repeated</i>. A single line may be assembled several times,
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for example:</p>
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<pre>:4 asl @
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table :32*5 dta 5
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</pre>
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<p>In lines with instructions or directives, a comment starts after
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the instruction/directive has been successfully parsed. That is, <b>xasm</b>
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does not require a special character to start a comment. However,
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you still can use one, because it is usually required for correct syntax
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highlighting in text editors.</p>
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<pre> lda foo ; this is a comment
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sta bar so it is
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tax #0 tax requires no operand, so #0 starts a comment
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</pre>
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<p><a name="new_pairing"/>You may put two instructions on the same line.
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In this case they have the same operand. For example:</p>
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<pre> eor:sta foo
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</pre>
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<p>is equivalent to</p>
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<pre> eor foo
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sta foo
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</pre>
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<p>Note that</p>
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<pre> lda:tax #0
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</pre><p>is allowed (<tt>#0</tt> is a comment for <tt>tax</tt>).</p>
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<h2>EXPRESSIONS</h2>
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<p>Expressions are numbers combined with operators and brackets.
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You should use square brackets, because parentheses are reserved
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for the indirect addressing.</p>
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<p>Numbers are 32-bit signed integers, in the range of -$7fffffff..$7fffffff.
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A number may be:</p>
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<ul>
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<li>a decimal number, e.g. <tt>-12345</tt></li>
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<li>a hexadecimal number, e.g. <tt>$abcd</tt></li>
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<li>a binary number, e.g. <tt>%10100101</tt></li>
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<li>an ASCII character, e.g. <tt>'a'</tt> or <tt>"a"</tt></li>
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<li>the origin counter value: <tt>*</tt></li>
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<li>a hardware register, e.g. <tt>^4e</tt></li>
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<li><a name="new_opcode"/>an op-code, e.g. <tt>{lda #0}</tt> equals
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<tt>$a9</tt></li>
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<li><a name="new_linecnt"/>the line repeat counter: <tt>#</tt></li>
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</ul>
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<p>Abbreviations of Atari hardware registers are provided to save you
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the trouble of typing two extra characters (<tt>^4e</tt> vs <tt>$d40e</tt>)
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and to ease porting software between Atari 8-bit computers and the Atari 5200
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console. These are very similar machines, one of the biggest differences is
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different location of hardware registers.</p>
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<table>
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<tr><th>Syntax</th><th>Chip</th>
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<th>Value in the Atari 8-bit<br/>computer mode (<tt>opt g-</tt>)</th>
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<th>Value in the Atari 5200<br/>game console mode (<tt>opt g+</tt>)</th>
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</tr>
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<tr><td><tt>^0x</tt></td><td>GTIA</td>
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<td><tt>$D00x</tt></td><td><tt>$C00x</tt></td></tr>
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<tr><td><tt>^1x</tt></td><td>GTIA</td>
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<td><tt>$D01x</tt></td><td><tt>$C01x</tt></td></tr>
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<tr><td><tt>^2x</tt></td><td>POKEY</td>
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<td><tt>$D20x</tt></td><td><tt>$E80x</tt></td></tr>
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<tr><td><tt>^3x</tt></td><td>PIA</td>
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<td><tt>$D30x</tt></td><td>error (there's no PIA chip)</td></tr>
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<tr><td><tt>^4x</tt></td><td>ANTIC</td>
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<td><tt>$D40x</tt></td><td><tt>$D40x</tt></td></tr>
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</table>
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<p>An op-code is the single-byte op-code of the instruction inside braces.
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The operand of the instruction is discarded and is necessary only for
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identifying the addressing mode. The instruction should begin just after
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the left brace and the right brace should immediately follow the operand
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or the instruction.
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<a name="new_op_op"/>You can skip the operand if the addressing mode
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is fixed. Examples:
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<tt>{lda #}</tt>, <tt>{jsr}</tt>, <tt>{bne}</tt>, <tt>{jmp ()}</tt>,
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<tt>{sta a:,x}</tt>.</p>
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<p>You can use the line repeat counter (<tt>#</tt>) in the repeated lines.
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It counts the iterations starting from zero. Examples:</p>
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<pre>:3 dta # ; generates three bytes: 00, 01, 02.
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line_lo :192 dta l(screen+40*#)
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line_hi :192 dta h(screen+40*#)
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dl :59 dta $4f,a(screen+40*#),0,$4f,a(screen+40*#),0
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</pre>
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<p>The follownig binary operators are supported:</p>
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<ul>
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<li><tt>+ </tt> Addition</li>
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<li><tt>- </tt> Subtraction</li>
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<li><tt>* </tt> Multiplication</li>
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<li><tt>/ </tt> Division</li>
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<li><tt>% </tt> Remainder</li>
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<li><tt>& </tt> Bitwise AND</li>
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<li><tt>| </tt> Bitwise OR</li>
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<li><tt>^ </tt> Bitwise XOR</li>
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<li><tt><<</tt> Arithmetic shift left</li>
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<li><tt>>></tt> Arithmetic shift right</li>
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<li><tt>= </tt> Equal</li>
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<li><tt>==</tt> Equal (same as <tt>=</tt>)</li>
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<li><tt><></tt> Not equal</li>
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<li><tt>!=</tt> Not equal (same as <tt><></tt>)</li>
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<li><tt>< </tt> Less than</li>
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<li><tt>> </tt> Greater than</li>
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<li><tt><=</tt> Less or equal</li>
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<li><tt>>=</tt> Greater or equal</li>
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<li><tt>&&</tt> Logical AND</li>
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<li><tt>||</tt> Logical OR</li>
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</ul>
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<p><a name="new_unary"/>The following unary operators are supported:</p>
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<ul>
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<li><tt>+ </tt> Plus (does nothing)</li>
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<li><tt>- </tt> Minus (changes the sign)</li>
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<li><tt>~ </tt> Bitwise NOT (complements all bits)</li>
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<li><tt>! </tt> Logical NOT (changes true to false and vice versa)</li>
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<li><tt>< </tt> Low (extracts the low byte)</li>
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<li><tt>> </tt> High (extracts the high byte)</li>
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</ul>
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<p>The operator precedence is following:</p>
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<table>
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<tr><td>first</td><td><tt>[]</tt></td>
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<td>(brackets)</td></tr>
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<tr><td> </td><td><tt>+ - ~ < ></tt></td>
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<td>(unary)</td></tr>
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<tr><td> </td><td><tt>* / % & << >></tt></td>
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<td>(binary)</td></tr>
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<tr><td> </td><td><tt>+ - | ^</tt></td>
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<td>(binary)</td></tr>
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<tr><td> </td><td><tt>= == <> != < > <= >=</tt></td>
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<td>(binary)</td></tr>
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<tr><td> </td><td><tt>!</tt></td>
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<td>(unary)</td></tr>
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<tr><td> </td><td><tt>&&</tt></td>
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<td>(binary)</td></tr>
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<tr><td>last </td><td><tt>||</tt></td>
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<td>(binary)</td></tr>
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</table>
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<p>Note that although the operators are similar to those used in C, C++
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and Java, their priorities are different than in these languages.</p>
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<p>Compare and logical operators assume that zero is false and a non-zero
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is true. They return 1 for true.</p>
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<p>While calculating an expression, signed 32-bit arithmetic is used.
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When range of 32 bits is exceeded, the '<tt>Arithmetic overflow</tt>' error
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is generated.</p>
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<h2>DIRECTIVES</h2>
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<dl>
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<dt><tt><b>EQU</b></tt> - assign a value of an expression to the label</dt>
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<dd>Note that a label represents a number, not a text macro.<br/>
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Examples:
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<pre>five equ 5
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here equ *
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</pre></dd>
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<dt><a name="new_opt"/><tt><b>OPT</b></tt> - set assembly options</dt>
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<dd>Five options are available:
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<ul>
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<li><tt>F</tt> - fill the space between <tt>ORG</tt>s
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with <tt>$FF</tt> bytes</li>
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<li><tt>G</tt> - Atari 5200 mode for hardware register abbreviations</li>
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<li><tt>H</tt> - generate Atari executable headers</li>
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<li><tt>L</tt> - generate listing</li>
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<li><tt>O</tt> - generate object file</li>
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</ul>
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You can turn any of these on or off.<br/>
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The default (if no <tt>OPT</tt> specified) is <tt>opt f-g-h+l+o+</tt>.<br/>
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Examples:
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<pre> opt l- listing off
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opt l+o- listing on, object file off
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opt f+g+h- useful for Atari 5200 cartridges - raw output format, 5200 hw regs
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</pre></dd>
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<dt><tt><b>ORG</b></tt> - change value of the origin counter</dt>
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<dd>You can set some options applied to the new header (if headers are
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enabled):
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<ul>
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<li><tt>a:</tt> tells <b>xasm</b> to always make a header, even it is
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unnecessary, like in <tt>ORG *</tt>.</li>
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<li><tt>f:</tt> works same as <tt>a:</tt>, but additionally tells to generate
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a <tt>$FF,$FF</tt> prefix before the header. <b>xasm</b> adds it
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at the beginning of the file by default, so use this option only if you want
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the <tt>$FF</tt>'s somewhere inside.</li>
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</ul>
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Examples:
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<pre> org $600
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org f:$700
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table org *+100
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</pre>
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In the latter example <tt>table</tt> points to 100 bytes
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of uninitialized data (label is assigned to <tt>*</tt>
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before the <tt>ORG</tt> directive is executed).
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<p><a name="new_orgr"/>Starting with version 2.6.0, <b>xasm</b> supports code
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that is relocated in the memory at runtime. Let's say you want your code
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to be run at the zero page. Typically you can't load it directly into this
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place, so you load it at a different address and then move at the runtime.
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<b>xasm</b> differentiates between the address that it used
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for code generation from the address that is used for generating
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Atari executable headers. <tt>org r:</tt> affects only the former one.
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Example:</p>
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<pre> org $8000
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ldx #code_length-1
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mva:rpl code_loaded,x z:code_zpage,x-
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jmp code_zpage
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code_loaded
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org r:$30
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code_zpage
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jmp * ; ... or something more sensible
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code_length equ *-code_zpage
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</pre>
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<p>Note that both <tt>*</tt> and label definitions use the counter used
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for code generation. There is no direct access to the other counter,
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because I think this is not useful. If you really need it, you can
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always type something like:</p>
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<pre>where_am_i equ *-code_zpage+code_loaded
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</pre></dd>
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<dt><a name="new_dta"/><tt><b>DTA</b></tt> - define data</dt>
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<dd>There are various data types:
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<ul>
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<li>integers
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<ul>
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<li>bytes: <tt>b(200)</tt> or simply <tt>200</tt></li>
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<li>words: <tt>a(10000)</tt></li>
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<li>low bytes of words: <tt>l(511)</tt> defines byte 255</li>
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<li>high bytes of words: <tt>h(511)</tt> defines byte 1</li>
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</ul>
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You may enter many expressions in parentheses and combine different types
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of data in a single line, separating things with commas.<br/>
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You may also define a sine lookup table. The syntax is:<br/>
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<tt>sin(center,amp,size,first,last)</tt><br/>
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where:
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<ul>
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<li><tt>center</tt> is a number which is added to every sine value</li>
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<li><tt>amp</tt> is the sine amplitude</li>
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<li><tt>size</tt> is the sine period</li>
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<li><tt>first,last</tt> define range of values in the table.
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They are optional. The default are <tt>0,size-1</tt>.</li>
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</ul>
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Example: <tt>dta a(sin(0,1000,256,0,63))</tt> defines a table of 64 words
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representing a quarter of sine with the amplitude of 1000.</li>
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<li>real numbers: <tt>r(-1.23456e12)</tt><br/>
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Real numbers are written in the 6-byte Atari Floating-Point format.</li>
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<li>text strings
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<ul>
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<li>ASCII strings: <tt>c'Text'</tt> or <tt>c"Text"</tt></li>
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<li>ANTIC strings: <tt>d'Text'</tt> or <tt>d"Text"</tt></li>
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</ul>
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A character string consists of any of characters surrounded by quotation
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marks. Within a string, a single quotation mark character is
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represented by two succesive quotation marks.<br/>
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Placing a <tt>*</tt> character after a string inverts
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the highest bit in every byte of the string.</li>
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</ul>
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Examples of <tt>DTA</tt>:
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<pre>
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dta b(1,2),3,a(1000,-1),l(12345,sin(0,127,256))
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dta d"ANTIC"*,c'It''s a string',$9b
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</pre></dd>
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<dt><tt><b>ICL</b></tt> - include another source file</dt>
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<dd>Specifies another file to be included in the assembly as if the contents
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of the referenced file appeared in place of the <tt>ICL</tt> statement.
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The included file may contain other <tt>ICL</tt> statements.
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The <tt>.ASX</tt> extension is added if none given.<br/>
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Examples:
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<pre>
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icl 'macros.asx'
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icl 'c:\atari\xasm\fileio'
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</pre></dd>
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<dt><tt><b>END</b></tt> - end assembling file</dt>
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<dd>Remaining part of the file is not assembled. If this statement does
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not occur, the assembler stops assembling when it encounters the end
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of the file.<br/>
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Example:
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<pre>
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end
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</pre></dd>
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<dt><tt><b>INS</b></tt> - insert contents of file</dt>
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<dd>Copies every byte of the specified file into the object file and updates
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the origin counter, as if these bytes were defined with <tt>DTA</tt>.<br/>
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You may specify a range of the inserted file. The syntax is following:
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<pre>
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ins 'file'[,offset[,length]]
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</pre>
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The first byte in a file has the offset of zero.<br/>
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If the offset is negative, it is counted from the end of the file.<br/>
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Examples:
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<pre>
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ins 'picture.raw'
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ins 'file',-256 insert last 256 bytes of file
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ins 'file',10,10 insert bytes 10..19 of file
|
|
</pre></dd>
|
|
<dt><tt><b>RUN</b></tt> - generate run address</dt>
|
|
<dd>An Atari executable program should specify a run address.
|
|
A program may be loaded in many areas of the memory and started from any
|
|
address.
|
|
<pre> run addr
|
|
</pre>
|
|
is equivalent to:
|
|
<pre> org $2e0
|
|
dta a(addr)
|
|
</pre>
|
|
Example:
|
|
<pre> run main
|
|
</pre></dd>
|
|
<dt><tt><b>INI</b></tt> - generate init address</dt>
|
|
<dd>An Atari executable program may have some routines which are executed
|
|
during the loading process. There may be many init blocks in one file.<br/>
|
|
Example:
|
|
<pre> ini showpic
|
|
</pre></dd>
|
|
<dt><tt><b>ERT</b></tt> - generate an error if an expression is true</dt>
|
|
<dd>Examples:
|
|
<pre> ert *>$c000
|
|
ert len1>$ff||len2>$ff
|
|
</pre></dd>
|
|
<dt><a name="new_eli"/><tt><b>IFT</b></tt> - assemble if expression is
|
|
true<br/>
|
|
<tt><b>ELI</b></tt> - else if<br/>
|
|
<tt><b>ELS</b></tt> - else<br/>
|
|
<tt><b>EIF</b></tt> - end if</dt>
|
|
<dd>With these directives you can construct fragments which
|
|
are assembled when a condition is met.
|
|
Conditional constructions can be nested.<br/>
|
|
Example:
|
|
<pre>noscr equ 1
|
|
widescr equ 1
|
|
ift noscr
|
|
lda #0
|
|
eli widescr
|
|
lda #$23
|
|
els
|
|
lda #$22
|
|
eif
|
|
sta $22f
|
|
</pre>
|
|
The above example can be rewritten using the line repeating feature:
|
|
<pre>noscr equ 1
|
|
widescr equ 1
|
|
:noscr lda #0
|
|
:!noscr&&widescr lda #$23
|
|
:!noscr&&!widescr lda #$22
|
|
sta $22f
|
|
</pre></dd>
|
|
</dl>
|
|
<h2>PSEUDO-COMMANDS</h2>
|
|
<p>Pseudo-commands are built-in macros.</p>
|
|
<dl>
|
|
<dt><tt><b>ADD</b></tt> - addition without carry</dt>
|
|
<dd>If you have ever programmed a 6502, you must have noticed that you had
|
|
to use a <tt>CLC</tt> before <tt>ADC</tt> for every simple addition.<br/>
|
|
<b>xasm</b> can do it for you. <tt>ADD</tt> replaces two instructions:
|
|
<tt>CLC</tt> and <tt>ADC</tt>.</dd>
|
|
<dt><tt><b>SUB</b></tt> - subtraction</dt>
|
|
<dd>It is <tt>SEC</tt> and <tt>SBC</tt>.</dd>
|
|
<dt><a name="new_repskip"/><tt><b>RCC, RCS, REQ, RMI, RNE, RPL, RVC,
|
|
RVS</b></tt> - conditional repeat</dt>
|
|
<dd>These are branches to the previous instruction.
|
|
They take no operand, because the branch target
|
|
is the address of previously assembled instruction.<br/>
|
|
Example:
|
|
<pre> ldx #0
|
|
mva:rne $500,x $600,x+
|
|
</pre>
|
|
The example code copies memory $500-$5ff to $600-$6ff.
|
|
Here is the same written with standard 6502 commands only:
|
|
<pre> ldx #0
|
|
loop lda $500,x
|
|
sta $600,x
|
|
inx
|
|
bne loop
|
|
</pre></dd>
|
|
<dt><tt><b>SCC, SCS, SEQ, SMI, SNE, SPL, SVC, SVS</b></tt> - conditional
|
|
skip</dt>
|
|
<dd>These are branches over the next instructions. No operand is required,
|
|
because the target is the address of the instruction following
|
|
the next instruction.<br/>
|
|
Example:
|
|
<pre> lda #40
|
|
add:sta $80
|
|
scc:inc $81
|
|
</pre>
|
|
In the above example the word-sized variable $80 is incremented by 40.</dd>
|
|
<dt><tt><b>JCC, JCS, JEQ, JMI, JNE, JPL, JVC, JVS</b></tt> - conditional
|
|
jumps</dt>
|
|
<dd>These are a kind of 'long' branches. While standard branches
|
|
(such as <tt>BNE</tt>) have range of -128..+127, these jumps have range
|
|
of all 64 kB.<br/>
|
|
Example:
|
|
<pre> jne dest
|
|
</pre>is equivalent to:
|
|
<pre> seq:jmp dest
|
|
</pre></dd>
|
|
<dt><tt><b>INW</b></tt> - increment word</dt>
|
|
<dd>Increments a 16-bit word in the memory.<br/>
|
|
Example:
|
|
<pre> inw dest
|
|
</pre>is equivalent to:
|
|
<pre> inc dest
|
|
sne:inc dest+1
|
|
</pre></dd>
|
|
<dt><tt><b>MVA, MVX, MVY</b></tt> - move byte using accumulator, X or Y</dt>
|
|
<dd>Each of these pseudo-commands requires two operands
|
|
and substitutes two commands:
|
|
<pre> mva source dest = lda source : sta dest
|
|
mvx source dest = ldx source : stx dest
|
|
mvy source dest = ldy source : sty dest
|
|
</pre></dd>
|
|
<dt><a name="new_mwinde"/><tt><b>MWA, MWX, MWY</b></tt> - move word using
|
|
accumulator, X or Y</dt>
|
|
<dd>These pseudo-commands require two operands
|
|
and are combinations of two <tt>MV*</tt>'s:
|
|
one to move the low byte, and the other to move the high byte.<br/>
|
|
You can't use indirect nor pseudo addressing mode with <tt>MW*</tt>.
|
|
Destination must be an absolute address (optionally indexed).<br/>
|
|
When source is also absolute, an <tt>mw* source dest</tt> will be:
|
|
<pre> mv* source dest
|
|
mv* source+1 dest+1
|
|
</pre>
|
|
When source is an immediate, an <tt>mw* #immed dest</tt> will be:
|
|
<pre> mv* <immed dest
|
|
mv* >immed dest+1
|
|
</pre>
|
|
When <tt><immed</tt> equals <tt>>immed</tt> and <tt>immed</tt>
|
|
is not forward-referenced, <b>xasm</b> uses an optimization:
|
|
<pre> mv* <immed dest
|
|
st* dest+1
|
|
</pre>
|
|
If possible, <tt>MWX</tt> and <tt>MWY</tt> use increment/decrement
|
|
commands. E.g. <tt>mwx #1 dest</tt> is assembled as:
|
|
<pre> ldx #1
|
|
stx dest
|
|
dex
|
|
stx dest+1
|
|
</pre></dd>
|
|
</dl>
|
|
<h2>ADDRESSING MODES</h2>
|
|
<p>All addressing modes are entered in the standard 6502 convention except for
|
|
the accumulator addressing mode, which should be marked with
|
|
the <tt>@</tt> character (as in Quick Assembler).</p>
|
|
<p>There are two extra immediate addressing modes:
|
|
<tt><</tt> and <tt>></tt>,
|
|
which use the low/high byte of a 16-bit word constant.
|
|
They are for Quick Assembler compatibility.
|
|
You can use traditional <tt>#<</tt> and <tt>#></tt>.
|
|
Note <tt>lda >$ff+5</tt> loads 1 (<tt>>$104</tt>),
|
|
while <tt>lda #>$ff+5</tt>
|
|
loads 5 (<tt>0+5</tt>) to the accumulator, because the unary operator
|
|
<tt>></tt> has a higher priority than the binary plus.</p>
|
|
<p>In absolute addressing modes, <b>xasm</b> examines the expression
|
|
and uses zero-page addressing mode if it supposes it's possible.
|
|
You may override it with <tt>a:</tt> and <tt>z:</tt> prefixes.</p>
|
|
<p>Examples:</p>
|
|
<pre>
|
|
nop
|
|
asl @
|
|
lda >$1234 assembles to lda #$12
|
|
lda $100,x
|
|
lda a:0 generates 16-bit address
|
|
jmp ($0a)
|
|
lda ($80),y
|
|
</pre>
|
|
<p>There are also pseudo addressing modes, which are similar to
|
|
pseudo-commands. You may use them just like standard addressing modes
|
|
in all 6502 commands and pseudo-commands, except for
|
|
<tt>MWA</tt>, <tt>MWX</tt> and <tt>MWY</tt>:</p>
|
|
<pre> cmd a,x+ = cmd a,x : inx
|
|
cmd a,x- = cmd a,x : dex
|
|
cmd a,y+ = cmd a,y : iny
|
|
cmd a,y- = cmd a,y : dey
|
|
cmd (z),y+ = cmd (z),y : iny
|
|
cmd (z),y- = cmd (z),y : dey
|
|
cmd (z,0) = ldx #0 : cmd (z,x)
|
|
cmd (z),0 = ldy #0 : cmd (z),y
|
|
<a name="new_adrmodes"/> cmd (z),0+ = ldy #0 : cmd (z),y : iny
|
|
cmd (z),0- = ldy #0 : cmd (z),y : dey
|
|
</pre>
|
|
<h2>CHANGES</h2>
|
|
<h3>Version 2.6.1 (2005-05-21)</h3>
|
|
<ul>
|
|
<li>no more "Arithmetic overflow" and "Division by zero" errors when correctly
|
|
using forward-referenced labels (bug found by Marcin Lewandowski)</li>
|
|
<li>the following now assembles:
|
|
<pre> ift 0
|
|
foo equ 1
|
|
ift foo
|
|
eif
|
|
eif
|
|
</pre>
|
|
(bug found by Adrian Matoga)</li>
|
|
<li>errors for non-existing <tt>INC @</tt> and <tt>DEC @</tt></li>
|
|
<li>negative numbers fixed in the listing</li>
|
|
</ul>
|
|
<h3>Version 2.6.0 (2005-02-07)</h3>
|
|
<ul>
|
|
<li>long file names are supported under Windows</li>
|
|
<li><a href="#new_orgr">support for code that is relocated at runtime</a></li>
|
|
<li><a href="#new_linecnt">line repeat counter</a></li>
|
|
<li>label values are now 32-bit, not just 17-bit</li>
|
|
<li>command-line options <tt>/n</tt> and <tt>/s</tt> are no longer
|
|
supported</li>
|
|
<li>fatal I/O errors (such as floppy not ready) no longer print the annoying
|
|
'<tt>Abort, Retry, Ignore</tt>' message</li>
|
|
</ul>
|
|
<h3>Version 2.5.2 (2002-10-03)</h3>
|
|
<ul>
|
|
<li>version 2.5.1 broke Unix EOLs - fixed</li>
|
|
<li>version 2.5.1 omitted all blank/comment/label lines, unless <tt>/c</tt>
|
|
was used</li>
|
|
</ul>
|
|
<h3>Version 2.5.1 (2002-08-21)</h3>
|
|
<ul>
|
|
<li>fixed assembling sources with Atari EOLs</li>
|
|
<li>blank/comment/label lines in false conditionals are now correctly omitted
|
|
in listing</li>
|
|
</ul>
|
|
<h3>Version 2.5 (2002-07-08)</h3>
|
|
<ul>
|
|
<li>fixed another bug, very similar to the previous one, e.g.
|
|
<pre> ift 0
|
|
:label nop
|
|
eif
|
|
</pre>
|
|
reported <tt>Label not defined before</tt> error for the repeat count</li>
|
|
<li><a href="#new_opt"><tt>OPT F+</tt> causes <tt>ORG</tt>s to fill the space
|
|
between the old and the new location with <tt>$FF</tt>s</a></li>
|
|
<li><a href="#new_opt"><tt>OPT G+</tt> enables Atari 5200 mode for hardware
|
|
register abbreviations</a></li>
|
|
</ul>
|
|
<h3>Version 2.4.1 (2002-06-27)</h3>
|
|
<ul>
|
|
<li>fixed a bug related to label definitions in conditionally skipped code,
|
|
e.g.
|
|
<pre> ift 0
|
|
label
|
|
eif
|
|
</pre>
|
|
reported <tt>No ORG specified</tt> error for the label definition</li>
|
|
</ul>
|
|
<h3>Version 2.4 (2002-05-22)</h3>
|
|
<ul>
|
|
<li>fixed a bug causing incorrect unary operator precedence</li>
|
|
<li>fixed wrong label value after a skip pseudo-command</li>
|
|
<li>the assembler is .EXE (.COM caused problems with DJGPP make due
|
|
to a bug in the DJGPP runtime)</li>
|
|
<li>the assembler is not compressed (so it occupies less space in the ZIP)</li>
|
|
<li>improved command-line parsing: options may be used before source file
|
|
name, tab character is a valid separator, <tt>/</tt> may be used as a directory
|
|
separator</li>
|
|
<li>error and warning messages are written to stderr, not stdout</li>
|
|
<li>added <tt>==</tt> (equals) operator, which is equivalent to
|
|
<tt>=</tt>(but is more natural for C/C++/Java programmers)</li>
|
|
<li><a href="#new_deflabel">added <tt>/d:label=value</tt> option: define
|
|
a label</a></li>
|
|
<li><a href="#new_fullpaths">added <tt>/p</tt> option: print full paths
|
|
in listing and error messages</a></li>
|
|
<li><a href="#new_quiet">added <tt>/q</tt> option: quiet mode</a></li>
|
|
<li><a href="#new_unlabels">added <tt>/u</tt> option: warn of unused
|
|
labels</a></li>
|
|
<li><a href="#new_opt">writing to the object file may be suppressed
|
|
with <tt>OPT O-</tt></a></li>
|
|
<li><a href="#new_eli">added <tt>ELI</tt> (else if) directive</a></li>
|
|
<li><a href="#new_mwinde"><tt>MWX</tt> and <tt>MWY</tt> may use
|
|
<tt>INX</tt>/<tt>DEX</tt> and <tt>INY</tt>/<tt>DEY</tt>, respectively,
|
|
for generating smaller code</a></li>
|
|
</ul>
|
|
<h3>Version 2.3 (2002-02-10)</h3>
|
|
<ul>
|
|
<li>double skip (e.g. <tt>SCC:SNE</tt>) bug fixed</li>
|
|
<li>real number two-digit exponent bug fixed</li>
|
|
<li>trailing spaces in a listing line are now truncated</li>
|
|
<li>label definitions allowed in blank, comment and repeated lines</li>
|
|
<li><a href="#new_unary">unary operators</a></li>
|
|
<li><a href="#new_dta"><tt>DTA</tt> implied byte mode</a></li>
|
|
<li><a href="#new_op_op">operand can be skipped for some op-codes</a></li>
|
|
</ul>
|
|
<h3>Version 2.2 (1999-09-10)</h3>
|
|
<ul>
|
|
<li>invalid absolute <tt>CPX</tt> and <tt>CPY</tt> op-codes fixed</li>
|
|
<li>fixed: addressing mode not checked for branch commands</li>
|
|
<li><tt>ICL</tt> in last line bug fixed</li>
|
|
<li><tt>OPT H-H+</tt> bug fixed</li>
|
|
<li>first <tt>ORG *</tt> bug fixed</li>
|
|
<li>origin setting not required until it is used</li>
|
|
<li>Unix ($0a), Macintosh ($0d) and Atari ($9b) EOLs allowed in the source</li>
|
|
<li>value of 'true' changed to 1</li>
|
|
<li><a href="#new_environment">setting environment variables on error
|
|
option</a></li>
|
|
<li>assembling only if source newer than object option</li>
|
|
<li><a href="#new_opcode">op-code extracting</a></li>
|
|
<li><a href="#new_linerep">line repeating</a></li>
|
|
<li><a href="#new_pairing">instructions pairing</a></li>
|
|
<li><a href="#new_repskip">conditional repeat and skip pseudo commands</a></li>
|
|
<li><a href="#new_adrmodes"><tt>(),0+</tt> and <tt>(),0-</tt> pseudo
|
|
addressing modes</a></li>
|
|
</ul>
|
|
<h3>Version 2.0 (1998-11-12)</h3>
|
|
<ul>
|
|
<li>truncating name of object bug fixed</li>
|
|
<li><tt>EQU</tt> and <tt>DTA</tt> forward reference bugs fixed</li>
|
|
<li>hex number recognizing bug fixed</li>
|
|
<li>now <tt>.OBX</tt> is the default extension for Atari executables</li>
|
|
<li>assembling options (switches and <tt>OPT</tt> directive)</li>
|
|
<li>listing generation</li>
|
|
<li>label table generation</li>
|
|
<li>conditional assembly</li>
|
|
<li>user errors</li>
|
|
<li>warnings</li>
|
|
<li>improved headers generation</li>
|
|
<li>improved expressions - 19 operators and brackets, 32-bit arithmetic</li>
|
|
<li>improved signed numbers</li>
|
|
<li>6 new pseudo commands (memory-to-memory move)</li>
|
|
<li>8 pseudo addressing modes</li>
|
|
<li>indirect conditional jumps</li>
|
|
<li>Atari floating-point numbers generation</li>
|
|
<li>improved <tt>INS</tt>: inserting specified part of file</li>
|
|
</ul>
|
|
<h3>Version 1.2 (1998-08-14)</h3>
|
|
<ul>
|
|
<li>first release</li>
|
|
</ul>
|
|
<h2>AUTHOR</h2>
|
|
<p>Piotr Fusik (<a href="mailto:fox@scene.pl">fox@scene.pl</a>)</p>
|
|
<h2>SEE ALSO</h2>
|
|
<p><a href="editors.htm">How to configure a text editor for a convenient use
|
|
of xasm</a></p>
|
|
<p>xasm home page
|
|
(<a href="http://xasm.atari.org">http://xasm.atari.org</a>)</p>
|
|
</body>
|
|
</html>
|