78 lines
3.0 KiB
HTML
78 lines
3.0 KiB
HTML
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<html lang="en">
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<head>
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<title>ARM-Instruction-Set - Using as</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Using as">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="ARM-Syntax.html#ARM-Syntax" title="ARM Syntax">
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<link rel="next" href="ARM_002dChars.html#ARM_002dChars" title="ARM-Chars">
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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) 1991-2019 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 1.3
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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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-->
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<meta http-equiv="Content-Style-Type" content="text/css">
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<style type="text/css"><!--
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pre.display { font-family:inherit }
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pre.format { font-family:inherit }
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pre.smalldisplay { font-family:inherit; font-size:smaller }
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pre.smalllisp { font-size:smaller }
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span.sc { font-variant:small-caps }
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span.roman { font-family:serif; font-weight:normal; }
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span.sansserif { font-family:sans-serif; font-weight:normal; }
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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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<a name="ARM-Instruction-Set"></a>
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<a name="ARM_002dInstruction_002dSet"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="ARM_002dChars.html#ARM_002dChars">ARM-Chars</a>,
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Up: <a rel="up" accesskey="u" href="ARM-Syntax.html#ARM-Syntax">ARM Syntax</a>
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<hr>
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</div>
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<h5 class="subsubsection">9.4.2.1 Instruction Set Syntax</h5>
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<p>Two slightly different syntaxes are support for ARM and THUMB
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instructions. The default, <code>divided</code>, uses the old style where
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ARM and THUMB instructions had their own, separate syntaxes. The new,
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<code>unified</code> syntax, which can be selected via the <code>.syntax</code>
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directive, and has the following main features:
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<ul>
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<li>Immediate operands do not require a <code>#</code> prefix.
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<li>The <code>IT</code> instruction may appear, and if it does it is validated
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against subsequent conditional affixes. In ARM mode it does not
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generate machine code, in THUMB mode it does.
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<li>For ARM instructions the conditional affixes always appear at the end
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of the instruction. For THUMB instructions conditional affixes can be
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used, but only inside the scope of an <code>IT</code> instruction.
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<li>All of the instructions new to the V6T2 architecture (and later) are
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available. (Only a few such instructions can be written in the
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<code>divided</code> syntax).
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<li>The <code>.N</code> and <code>.W</code> suffixes are recognized and honored.
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<li>All instructions set the flags if and only if they have an <code>s</code>
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affix.
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</ul>
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</body></html>
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