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| <title>Using as: XGATE-Syntax</title> |
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| <a name="XGATE_002dSyntax"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="XGATE_002dDirectives.html#XGATE_002dDirectives" accesskey="n" rel="next">XGATE-Directives</a>, Previous: <a href="XGATE_002dOpts.html#XGATE_002dOpts" accesskey="p" rel="prev">XGATE-Opts</a>, Up: <a href="XGATE_002dDependent.html#XGATE_002dDependent" accesskey="u" rel="up">XGATE-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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| <hr> |
| <a name="Syntax-30"></a> |
| <h4 class="subsection">9.50.2 Syntax</h4> |
| |
| <a name="index-XGATE-syntax"></a> |
| <a name="index-syntax_002c-XGATE"></a> |
| |
| <p>In XGATE RISC syntax, the instruction name comes first and it may |
| be followed by up to three operands. Operands are separated by commas |
| (‘<samp>,</samp>’). <code>as</code> will complain if too many operands are specified |
| for a given instruction. The same will happen if you specified too few |
| operands. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">nop |
| ldl #23 |
| CMP R1, R2 |
| </pre></div> |
| |
| <a name="index-line-comment-character_002c-XGATE"></a> |
| <a name="index-XGATE-line-comment-character"></a> |
| <p>The presence of a ‘<samp>;</samp>’ character or a ‘<samp>!</samp>’ character anywhere |
| on a line indicates the start of a comment that extends to the end of |
| that line. |
| </p> |
| <p>A ‘<samp>*</samp>’ or a ‘<samp>#</samp>’ character at the start of a line also |
| introduces a line comment, but these characters do not work elsewhere |
| on the line. If the first character of the line is a ‘<samp>#</samp>’ then as |
| well as starting a comment, the line could also be logical line number |
| directive (see <a href="Comments.html#Comments">Comments</a>) or a preprocessor control command |
| (see <a href="Preprocessing.html#Preprocessing">Preprocessing</a>). |
| </p> |
| <a name="index-line-separator_002c-XGATE"></a> |
| <a name="index-statement-separator_002c-XGATE"></a> |
| <a name="index-XGATE-line-separator"></a> |
| <p>The XGATE assembler does not currently support a line separator |
| character. |
| </p> |
| <a name="index-XGATE-addressing-modes"></a> |
| <a name="index-addressing-modes_002c-XGATE"></a> |
| <p>The following addressing modes are understood for XGATE: |
| </p><dl compact="compact"> |
| <dt><em>Inherent</em></dt> |
| <dd><p>‘<samp></samp>’ |
| </p> |
| </dd> |
| <dt><em>Immediate 3 Bit Wide</em></dt> |
| <dd><p>‘<samp>#<var>number</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Immediate 4 Bit Wide</em></dt> |
| <dd><p>‘<samp>#<var>number</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Immediate 8 Bit Wide</em></dt> |
| <dd><p>‘<samp>#<var>number</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Monadic Addressing</em></dt> |
| <dd><p>‘<samp><var>reg</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Dyadic Addressing</em></dt> |
| <dd><p>‘<samp><var>reg</var>, <var>reg</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Triadic Addressing</em></dt> |
| <dd><p>‘<samp><var>reg</var>, <var>reg</var>, <var>reg</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Relative Addressing 9 Bit Wide</em></dt> |
| <dd><p>‘<samp>*<var>symbol</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Relative Addressing 10 Bit Wide</em></dt> |
| <dd><p>‘<samp>*<var>symbol</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Index Register plus Immediate Offset</em></dt> |
| <dd><p>‘<samp><var>reg</var>, (<var>reg</var>, #<var>number</var>)</samp>’ |
| </p> |
| </dd> |
| <dt><em>Index Register plus Register Offset</em></dt> |
| <dd><p>‘<samp><var>reg</var>, <var>reg</var>, <var>reg</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Index Register plus Register Offset with Post-increment</em></dt> |
| <dd><p>‘<samp><var>reg</var>, <var>reg</var>, <var>reg</var>+</samp>’ |
| </p> |
| </dd> |
| <dt><em>Index Register plus Register Offset with Pre-decrement</em></dt> |
| <dd><p>‘<samp><var>reg</var>, <var>reg</var>, -<var>reg</var></samp>’ |
| </p> |
| <p>The register can be either ‘<samp>R0</samp>’, ‘<samp>R1</samp>’, ‘<samp>R2</samp>’, ‘<samp>R3</samp>’, |
| ‘<samp>R4</samp>’, ‘<samp>R5</samp>’, ‘<samp>R6</samp>’ or ‘<samp>R7</samp>’. |
| </p> |
| </dd> |
| </dl> |
| |
| <p>Convience macro opcodes to deal with 16-bit values have been added. |
| </p> |
| <dl compact="compact"> |
| <dt><em>Immediate 16 Bit Wide</em></dt> |
| <dd><p>‘<samp>#<var>number</var></samp>’, or ‘<samp>*<var>symbol</var></samp>’ |
| </p> |
| <p>For example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">ldw R1, #1024 |
| ldw R3, timer |
| ldw R1, (R1, #0) |
| COM R1 |
| stw R2, (R1, #0) |
| </pre></div> |
| </dd> |
| </dl> |
| |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="XGATE_002dDirectives.html#XGATE_002dDirectives" accesskey="n" rel="next">XGATE-Directives</a>, Previous: <a href="XGATE_002dOpts.html#XGATE_002dOpts" accesskey="p" rel="prev">XGATE-Opts</a>, Up: <a href="XGATE_002dDependent.html#XGATE_002dDependent" accesskey="u" rel="up">XGATE-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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