107 lines
5.9 KiB
HTML
107 lines
5.9 KiB
HTML
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<html lang="en">
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<head>
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<title>D30V-Chars - Using as</title>
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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="D30V_002dSyntax.html#D30V_002dSyntax" title="D30V-Syntax">
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<link rel="prev" href="D30V_002dSubs.html#D30V_002dSubs" title="D30V-Subs">
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<link rel="next" href="D30V_002dGuarded.html#D30V_002dGuarded" title="D30V-Guarded">
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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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<style type="text/css"><!--
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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="D30V-Chars"></a>
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<a name="D30V_002dChars"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="D30V_002dGuarded.html#D30V_002dGuarded">D30V-Guarded</a>,
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Previous: <a rel="previous" accesskey="p" href="D30V_002dSubs.html#D30V_002dSubs">D30V-Subs</a>,
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Up: <a rel="up" accesskey="u" href="D30V_002dSyntax.html#D30V_002dSyntax">D30V-Syntax</a>
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<hr>
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</div>
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<h5 class="subsubsection">9.12.2.3 Special Characters</h5>
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<p><a name="index-line-comment-character_002c-D30V-1014"></a><a name="index-D30V-line-comment-character-1015"></a>A semicolon (‘<samp><span class="samp">;</span></samp>’) can be used anywhere on a line to start a
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comment that extends to the end of the line.
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<p>If a ‘<samp><span class="samp">#</span></samp>’ appears as the first character of a line, the whole line
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is treated as a comment, but in this case the line could also be a
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logical line number directive (see <a href="Comments.html#Comments">Comments</a>) or a preprocessor
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control command (see <a href="Preprocessing.html#Preprocessing">Preprocessing</a>).
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<p><a name="index-sub_002dinstruction-ordering_002c-D30V-1016"></a><a name="index-D30V-sub_002dinstruction-ordering-1017"></a>Sub-instructions may be executed in order, in reverse-order, or in parallel.
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Instructions listed in the standard one-per-line format will be executed
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sequentially unless you use the ‘<samp><span class="samp">-O</span></samp>’ option.
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<p>To specify the executing order, use the following symbols:
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<dl>
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<dt>‘<samp><span class="samp">-></span></samp>’<dd>Sequential with instruction on the left first.
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<br><dt>‘<samp><span class="samp"><-</span></samp>’<dd>Sequential with instruction on the right first.
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<br><dt>‘<samp><span class="samp">||</span></samp>’<dd>Parallel
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</dl>
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<p>The D30V syntax allows either one instruction per line, one instruction per line with
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the execution symbol, or two instructions per line. For example
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<dl>
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<dt><code>abs r2,r3 -> abs r4,r5</code><dd>Execute these sequentially. The instruction on the right is in the right
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container and is executed second.
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<br><dt><code>abs r2,r3 <- abs r4,r5</code><dd>Execute these reverse-sequentially. The instruction on the right is in the right
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container, and is executed first.
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<br><dt><code>abs r2,r3 || abs r4,r5</code><dd>Execute these in parallel.
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<br><dt><code>ldw r2,@(r3,r4) ||</code><dt><code>mulx r6,r8,r9</code><dd>Two-line format. Execute these in parallel.
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<br><dt><code>mulx a0,r8,r9</code><dt><code>stw r2,@(r3,r4)</code><dd>Two-line format. Execute these sequentially unless ‘<samp><span class="samp">-O</span></samp>’ option is
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used. If the ‘<samp><span class="samp">-O</span></samp>’ option is used, the assembler will determine if
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the instructions could be done in parallel (the above two instructions
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can be done in parallel), and if so, emit them as parallel instructions.
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The assembler will put them in the proper containers. In the above
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example, the assembler will put the ‘<samp><span class="samp">stw</span></samp>’ instruction in left
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container and the ‘<samp><span class="samp">mulx</span></samp>’ instruction in the right container.
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<br><dt><code>stw r2,@(r3,r4) -></code><dt><code>mulx a0,r8,r9</code><dd>Two-line format. Execute the ‘<samp><span class="samp">stw</span></samp>’ instruction followed by the
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‘<samp><span class="samp">mulx</span></samp>’ instruction sequentially. The first instruction goes in the
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left container and the second instruction goes into right container.
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The assembler will give an error if the machine ordering constraints are
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violated.
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<br><dt><code>stw r2,@(r3,r4) <-</code><dt><code>mulx a0,r8,r9</code><dd>Same as previous example, except that the ‘<samp><span class="samp">mulx</span></samp>’ instruction is
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executed before the ‘<samp><span class="samp">stw</span></samp>’ instruction.
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</dl>
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<p><a name="index-symbol-names_002c-_0040samp_007b_0024_007d-in-1018"></a><a name="index-g_t_0040code_007b_0024_007d-in-symbol-names-1019"></a>Since ‘<samp><span class="samp">$</span></samp>’ has no special meaning, you may use it in symbol names.
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</body></html>
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