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| <title>Using as: M32C-Modifiers</title> |
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| <a name="M32C_002dModifiers"></a> |
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| Next: <a href="M32C_002dChars.html#M32C_002dChars" accesskey="n" rel="next">M32C-Chars</a>, Up: <a href="M32C_002dSyntax.html#M32C_002dSyntax" accesskey="u" rel="up">M32C-Syntax</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="Symbolic-Operand-Modifiers"></a> |
| <h4 class="subsubsection">9.21.2.1 Symbolic Operand Modifiers</h4> |
| |
| <a name="index-M32C-modifiers"></a> |
| <a name="index-modifiers_002c-M32C"></a> |
| |
| <p>The assembler supports several modifiers when using symbol addresses |
| in M32C instruction operands. The general syntax is the following: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">%modifier(symbol) |
| </pre></div> |
| |
| <dl compact="compact"> |
| <dd><a name="index-symbol-modifiers-2"></a> |
| |
| </dd> |
| <dt><code>%dsp8</code></dt> |
| <dt><code>%dsp16</code></dt> |
| <dd> |
| <p>These modifiers override the assembler’s assumptions about how big a |
| symbol’s address is. Normally, when it sees an operand like |
| ‘<samp>sym[a0]</samp>’ it assumes ‘<samp>sym</samp>’ may require the widest |
| displacement field (16 bits for ‘<samp>-m16c</samp>’, 24 bits for |
| ‘<samp>-m32c</samp>’). These modifiers tell it to assume the address will fit |
| in an 8 or 16 bit (respectively) unsigned displacement. Note that, of |
| course, if it doesn’t actually fit you will get linker errors. Example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">mov.w %dsp8(sym)[a0],r1 |
| mov.b #0,%dsp8(sym)[a0] |
| </pre></div> |
| |
| </dd> |
| <dt><code>%hi8</code></dt> |
| <dd> |
| <p>This modifier allows you to load bits 16 through 23 of a 24 bit |
| address into an 8 bit register. This is useful with, for example, the |
| M16C ‘<samp>smovf</samp>’ instruction, which expects a 20 bit address in |
| ‘<samp>r1h</samp>’ and ‘<samp>a0</samp>’. Example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">mov.b #%hi8(sym),r1h |
| mov.w #%lo16(sym),a0 |
| smovf.b |
| </pre></div> |
| |
| </dd> |
| <dt><code>%lo16</code></dt> |
| <dd> |
| <p>Likewise, this modifier allows you to load bits 0 through 15 of a 24 |
| bit address into a 16 bit register. |
| </p> |
| </dd> |
| <dt><code>%hi16</code></dt> |
| <dd> |
| <p>This modifier allows you to load bits 16 through 31 of a 32 bit |
| address into a 16 bit register. While the M32C family only has 24 |
| bits of address space, it does support addresses in pairs of 16 bit |
| registers (like ‘<samp>a1a0</samp>’ for the ‘<samp>lde</samp>’ instruction). This |
| modifier is for loading the upper half in such cases. Example: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">mov.w #%hi16(sym),a1 |
| mov.w #%lo16(sym),a0 |
| … |
| lde.w [a1a0],r1 |
| </pre></div> |
| |
| </dd> |
| </dl> |
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