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| <title>Using as: M68HC11-Syntax</title> |
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| <a name="M68HC11_002dSyntax"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="M68HC11_002dModifiers.html#M68HC11_002dModifiers" accesskey="n" rel="next">M68HC11-Modifiers</a>, Previous: <a href="M68HC11_002dOpts.html#M68HC11_002dOpts" accesskey="p" rel="prev">M68HC11-Opts</a>, Up: <a href="M68HC11_002dDependent.html#M68HC11_002dDependent" accesskey="u" rel="up">M68HC11-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> |
| </div> |
| <hr> |
| <a name="Syntax-17"></a> |
| <h4 class="subsection">9.24.2 Syntax</h4> |
| |
| <a name="index-M68HC11-syntax"></a> |
| <a name="index-syntax_002c-M68HC11"></a> |
| |
| <p>In the M68HC11 syntax, the instruction name comes first and it may |
| be followed by one or several operands (up to three). Operands are |
| separated by comma (‘<samp>,</samp>’). In the normal mode, |
| <code>as</code> will complain if too many operands are specified for |
| a given instruction. In the MRI mode (turned on with ‘<samp>-M</samp>’ option), |
| it will treat them as comments. Example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">inx |
| lda #23 |
| bset 2,x #4 |
| brclr *bot #8 foo |
| </pre></div> |
| |
| <a name="index-line-comment-character_002c-M68HC11"></a> |
| <a name="index-M68HC11-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-M68HC11"></a> |
| <a name="index-statement-separator_002c-M68HC11"></a> |
| <a name="index-M68HC11-line-separator"></a> |
| <p>The M68HC11 assembler does not currently support a line separator |
| character. |
| </p> |
| <a name="index-M68HC11-addressing-modes"></a> |
| <a name="index-addressing-modes_002c-M68HC11"></a> |
| <p>The following addressing modes are understood for 68HC11 and 68HC12: |
| </p><dl compact="compact"> |
| <dt><em>Immediate</em></dt> |
| <dd><p>‘<samp>#<var>number</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Address Register</em></dt> |
| <dd><p>‘<samp><var>number</var>,X</samp>’, ‘<samp><var>number</var>,Y</samp>’ |
| </p> |
| <p>The <var>number</var> may be omitted in which case 0 is assumed. |
| </p> |
| </dd> |
| <dt><em>Direct Addressing mode</em></dt> |
| <dd><p>‘<samp>*<var>symbol</var></samp>’, or ‘<samp>*<var>digits</var></samp>’ |
| </p> |
| </dd> |
| <dt><em>Absolute</em></dt> |
| <dd><p>‘<samp><var>symbol</var></samp>’, or ‘<samp><var>digits</var></samp>’ |
| </p></dd> |
| </dl> |
| |
| <p>The M68HC12 has other more complex addressing modes. All of them |
| are supported and they are represented below: |
| </p> |
| <dl compact="compact"> |
| <dt><em>Constant Offset Indexed Addressing Mode</em></dt> |
| <dd><p>‘<samp><var>number</var>,<var>reg</var></samp>’ |
| </p> |
| <p>The <var>number</var> may be omitted in which case 0 is assumed. |
| The register can be either ‘<samp>X</samp>’, ‘<samp>Y</samp>’, ‘<samp>SP</samp>’ or |
| ‘<samp>PC</samp>’. The assembler will use the smaller post-byte definition |
| according to the constant value (5-bit constant offset, 9-bit constant |
| offset or 16-bit constant offset). If the constant is not known by |
| the assembler it will use the 16-bit constant offset post-byte and the value |
| will be resolved at link time. |
| </p> |
| </dd> |
| <dt><em>Offset Indexed Indirect</em></dt> |
| <dd><p>‘<samp>[<var>number</var>,<var>reg</var>]</samp>’ |
| </p> |
| <p>The register can be either ‘<samp>X</samp>’, ‘<samp>Y</samp>’, ‘<samp>SP</samp>’ or ‘<samp>PC</samp>’. |
| </p> |
| </dd> |
| <dt><em>Auto Pre-Increment/Pre-Decrement/Post-Increment/Post-Decrement</em></dt> |
| <dd><p>‘<samp><var>number</var>,-<var>reg</var></samp>’ |
| ‘<samp><var>number</var>,+<var>reg</var></samp>’ |
| ‘<samp><var>number</var>,<var>reg</var>-</samp>’ |
| ‘<samp><var>number</var>,<var>reg</var>+</samp>’ |
| </p> |
| <p>The number must be in the range ‘<samp>-8</samp>’..‘<samp>+8</samp>’ and must not be 0. |
| The register can be either ‘<samp>X</samp>’, ‘<samp>Y</samp>’, ‘<samp>SP</samp>’ or ‘<samp>PC</samp>’. |
| </p> |
| </dd> |
| <dt><em>Accumulator Offset</em></dt> |
| <dd><p>‘<samp><var>acc</var>,<var>reg</var></samp>’ |
| </p> |
| <p>The accumulator register can be either ‘<samp>A</samp>’, ‘<samp>B</samp>’ or ‘<samp>D</samp>’. |
| The register can be either ‘<samp>X</samp>’, ‘<samp>Y</samp>’, ‘<samp>SP</samp>’ or ‘<samp>PC</samp>’. |
| </p> |
| </dd> |
| <dt><em>Accumulator D offset indexed-indirect</em></dt> |
| <dd><p>‘<samp>[D,<var>reg</var>]</samp>’ |
| </p> |
| <p>The register can be either ‘<samp>X</samp>’, ‘<samp>Y</samp>’, ‘<samp>SP</samp>’ or ‘<samp>PC</samp>’. |
| </p> |
| </dd> |
| </dl> |
| |
| <p>For example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">ldab 1024,sp |
| ldd [10,x] |
| orab 3,+x |
| stab -2,y- |
| ldx a,pc |
| sty [d,sp] |
| </pre></div> |
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| Next: <a href="M68HC11_002dModifiers.html#M68HC11_002dModifiers" accesskey="n" rel="next">M68HC11-Modifiers</a>, Previous: <a href="M68HC11_002dOpts.html#M68HC11_002dOpts" accesskey="p" rel="prev">M68HC11-Opts</a>, Up: <a href="M68HC11_002dDependent.html#M68HC11_002dDependent" accesskey="u" rel="up">M68HC11-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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