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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gccint/Bit_002dFields.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
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diff --git a/share/doc/gccint/Bit_002dFields.html b/share/doc/gccint/Bit_002dFields.html new file mode 100644 index 0000000..7e6783e --- /dev/null +++ b/share/doc/gccint/Bit_002dFields.html @@ -0,0 +1,126 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>GNU Compiler Collection (GCC) Internals: Bit-Fields</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Bit-Fields"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Bit-Fields"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="RTL.html#RTL" rel="up" title="RTL"> +<link href="Vector-Operations.html#Vector-Operations" rel="next" title="Vector Operations"> +<link href="Comparisons.html#Comparisons" rel="previous" title="Comparisons"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Bit_002dFields"></a> +<div class="header"> +<p> +Next: <a href="Vector-Operations.html#Vector-Operations" accesskey="n" rel="next">Vector Operations</a>, Previous: <a href="Comparisons.html#Comparisons" accesskey="p" rel="previous">Comparisons</a>, Up: <a href="RTL.html#RTL" accesskey="u" rel="up">RTL</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Bit_002dFields-1"></a> +<h3 class="section">14.11 Bit-Fields</h3> +<a name="index-bit_002dfields"></a> + +<p>Special expression codes exist to represent bit-field instructions. +</p> +<dl compact="compact"> +<dd><a name="index-sign_005fextract"></a> +<a name="index-BITS_005fBIG_005fENDIAN_002c-effect-on-sign_005fextract"></a> +</dd> +<dt><code>(sign_extract:<var>m</var> <var>loc</var> <var>size</var> <var>pos</var>)</code></dt> +<dd><p>This represents a reference to a sign-extended bit-field contained or +starting in <var>loc</var> (a memory or register reference). The bit-field +is <var>size</var> bits wide and starts at bit <var>pos</var>. The compilation +option <code>BITS_BIG_ENDIAN</code> says which end of the memory unit +<var>pos</var> counts from. +</p> +<p>If <var>loc</var> is in memory, its mode must be a single-byte integer mode. +If <var>loc</var> is in a register, the mode to use is specified by the +operand of the <code>insv</code> or <code>extv</code> pattern +(see <a href="Standard-Names.html#Standard-Names">Standard Names</a>) and is usually a full-word integer mode, +which is the default if none is specified. +</p> +<p>The mode of <var>pos</var> is machine-specific and is also specified +in the <code>insv</code> or <code>extv</code> pattern. +</p> +<p>The mode <var>m</var> is the same as the mode that would be used for +<var>loc</var> if it were a register. +</p> +<p>A <code>sign_extract</code> cannot appear as an lvalue, or part thereof, +in RTL. +</p> +<a name="index-zero_005fextract"></a> +</dd> +<dt><code>(zero_extract:<var>m</var> <var>loc</var> <var>size</var> <var>pos</var>)</code></dt> +<dd><p>Like <code>sign_extract</code> but refers to an unsigned or zero-extended +bit-field. The same sequence of bits are extracted, but they +are filled to an entire word with zeros instead of by sign-extension. +</p> +<p>Unlike <code>sign_extract</code>, this type of expressions can be lvalues +in RTL; they may appear on the left side of an assignment, indicating +insertion of a value into the specified bit-field. +</p></dd> +</dl> + + + + +</body> +</html> |