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| <title>Using as: Literal Position Directive</title> |
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| <a name="literal_005fposition"></a> |
| <h4 class="subsubsection">9.52.5.5 literal_position</h4> |
| <a name="index-literal_005fposition-directive"></a> |
| |
| <p>When using ‘<samp>--text-section-literals</samp>’ to place literals inline |
| in the section being assembled, the <code>.literal_position</code> directive |
| can be used to mark a potential location for a literal pool. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample"> .literal_position |
| </pre></div> |
| |
| <p>The <code>.literal_position</code> directive is ignored when the |
| ‘<samp>--text-section-literals</samp>’ option is not used or when |
| <code>L32R</code> instructions use the absolute addressing mode. |
| </p> |
| <p>The assembler will automatically place text section literal pools |
| before <code>ENTRY</code> instructions, so the <code>.literal_position</code> |
| directive is only needed to specify some other location for a literal |
| pool. You may need to add an explicit jump instruction to skip over an |
| inline literal pool. |
| </p> |
| <p>For example, an interrupt vector does not begin with an <code>ENTRY</code> |
| instruction so the assembler will be unable to automatically find a good |
| place to put a literal pool. Moreover, the code for the interrupt |
| vector must be at a specific starting address, so the literal pool |
| cannot come before the start of the code. The literal pool for the |
| vector must be explicitly positioned in the middle of the vector (before |
| any uses of the literals, due to the negative offsets used by |
| PC-relative <code>L32R</code> instructions). The <code>.literal_position</code> |
| directive can be used to do this. In the following code, the literal |
| for ‘<samp>M</samp>’ will automatically be aligned correctly and is placed after |
| the unconditional jump. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample"> .global M |
| code_start: |
| </pre><pre class="smallexample"> j continue |
| .literal_position |
| .align 4 |
| </pre><pre class="smallexample">continue: |
| movi a4, M |
| </pre></div> |
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