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75 lines
3.4 KiB
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75 lines
3.4 KiB
HTML
15 years ago
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<title>CRIS-Expand - Using as</title>
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<meta name="description" content="Using as">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="CRIS_002dDependent.html#CRIS_002dDependent" title="CRIS-Dependent">
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<link rel="prev" href="CRIS_002dOpts.html#CRIS_002dOpts" title="CRIS-Opts">
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<link rel="next" href="CRIS_002dSymbols.html#CRIS_002dSymbols" title="CRIS-Symbols">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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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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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.1
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, with no Front-Cover Texts, and with no
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Back-Cover Texts. A copy of the license is included in the
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section entitled ``GNU Free Documentation License''.
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man end-->
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--></style>
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</head>
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<body>
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<div class="node">
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<p>
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<a name="CRIS_002dExpand"></a>Next: <a rel="next" accesskey="n" href="CRIS_002dSymbols.html#CRIS_002dSymbols">CRIS-Symbols</a>,
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Previous: <a rel="previous" accesskey="p" href="CRIS_002dOpts.html#CRIS_002dOpts">CRIS-Opts</a>,
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Up: <a rel="up" accesskey="u" href="CRIS_002dDependent.html#CRIS_002dDependent">CRIS-Dependent</a>
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<hr><br>
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</div>
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<h4 class="subsection">9.7.2 Instruction expansion</h4>
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<p><a name="index-instruction-expansion_002c-CRIS-693"></a><a name="index-CRIS-instruction-expansion-694"></a><code>as</code> will silently choose an instruction that fits
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the operand size for <span class="samp">[register+constant]</span> operands. For
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example, the offset <code>127</code> in <code>move.d [r3+127],r4</code> fits
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in an instruction using a signed-byte offset. Similarly,
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<code>move.d [r2+32767],r1</code> will generate an instruction using a
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16-bit offset. For symbolic expressions and constants that do
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not fit in 16 bits including the sign bit, a 32-bit offset is
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generated.
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<p>For branches, <code>as</code> will expand from a 16-bit branch
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instruction into a sequence of instructions that can reach a
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full 32-bit address. Since this does not correspond to a single
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instruction, such expansions can optionally be warned about.
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See <a href="CRIS_002dOpts.html#CRIS_002dOpts">CRIS-Opts</a>.
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<p>If the operand is found to fit the range, a <code>lapc</code> mnemonic
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will translate to a <code>lapcq</code> instruction. Use <code>lapc.d</code>
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to force the 32-bit <code>lapc</code> instruction.
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<p>Similarly, the <code>addo</code> mnemonic will translate to the
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shortest fitting instruction of <code>addoq</code>, <code>addo.w</code> and
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<code>addo.d</code>, when used with a operand that is a constant known
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at assembly time.
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</body></html>
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