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87 lines
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<title>Literal Position Directive - Using as</title>
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This file documents the GNU Assembler "as".
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Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
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2006, 2007 Free Software Foundation, Inc.
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<p>
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<a name="Literal-Position-Directive"></a>Next: <a rel="next" accesskey="n" href="Literal-Prefix-Directive.html#Literal-Prefix-Directive">Literal Prefix Directive</a>,
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Previous: <a rel="previous" accesskey="p" href="Literal-Directive.html#Literal-Directive">Literal Directive</a>,
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Up: <a rel="up" accesskey="u" href="Xtensa-Directives.html#Xtensa-Directives">Xtensa Directives</a>
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<h5 class="subsubsection">9.36.5.5 literal_position</h5>
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<p><a name="index-_0040code_007bliteral_005fposition_007d-directive-1891"></a>
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When using <span class="samp">--text-section-literals</span> to place literals inline
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in the section being assembled, the <code>.literal_position</code> directive
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can be used to mark a potential location for a literal pool.
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<pre class="smallexample"> .literal_position
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</pre>
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<p>The <code>.literal_position</code> directive is ignored when the
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<span class="samp">--text-section-literals</span> option is not used or when
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<code>L32R</code> instructions use the absolute addressing mode.
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<p>The assembler will automatically place text section literal pools
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before <code>ENTRY</code> instructions, so the <code>.literal_position</code>
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directive is only needed to specify some other location for a literal
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pool. You may need to add an explicit jump instruction to skip over an
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inline literal pool.
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<p>For example, an interrupt vector does not begin with an <code>ENTRY</code>
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instruction so the assembler will be unable to automatically find a good
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place to put a literal pool. Moreover, the code for the interrupt
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vector must be at a specific starting address, so the literal pool
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cannot come before the start of the code. The literal pool for the
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vector must be explicitly positioned in the middle of the vector (before
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any uses of the literals, due to the negative offsets used by
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PC-relative <code>L32R</code> instructions). The <code>.literal_position</code>
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directive can be used to do this. In the following code, the literal
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for <span class="samp">M</span> will automatically be aligned correctly and is placed after
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the unconditional jump.
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<pre class="smallexample"> .global M
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code_start:
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j continue
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.literal_position
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.align 4
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continue:
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movi a4, M
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</pre>
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</body></html>
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