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| <title>Using as: ARM Mapping Symbols</title> |
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| <a name="Mapping-Symbols-1"></a> |
| <h4 class="subsection">9.4.6 Mapping Symbols</h4> |
| |
| <p>The ARM ELF specification requires that special symbols be inserted |
| into object files to mark certain features: |
| </p> |
| <dl compact="compact"> |
| <dd> |
| <a name="index-_0024a"></a> |
| </dd> |
| <dt><code>$a</code></dt> |
| <dd><p>At the start of a region of code containing ARM instructions. |
| </p> |
| <a name="index-_0024t"></a> |
| </dd> |
| <dt><code>$t</code></dt> |
| <dd><p>At the start of a region of code containing THUMB instructions. |
| </p> |
| <a name="index-_0024d-1"></a> |
| </dd> |
| <dt><code>$d</code></dt> |
| <dd><p>At the start of a region of data. |
| </p> |
| </dd> |
| </dl> |
| |
| <p>The assembler will automatically insert these symbols for you - there |
| is no need to code them yourself. Support for tagging symbols ($b, |
| $f, $p and $m) which is also mentioned in the current ARM ELF |
| specification is not implemented. This is because they have been |
| dropped from the new EABI and so tools cannot rely upon their |
| presence. |
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