diff options
| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
|---|---|---|
| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gccint/Floating-Point.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
Diffstat (limited to 'share/doc/gccint/Floating-Point.html')
| -rw-r--r-- | share/doc/gccint/Floating-Point.html | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/share/doc/gccint/Floating-Point.html b/share/doc/gccint/Floating-Point.html new file mode 100644 index 0000000..4596a27 --- /dev/null +++ b/share/doc/gccint/Floating-Point.html @@ -0,0 +1,162 @@ +<!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: Floating Point</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Floating Point"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Floating Point"> +<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="Target-Macros.html#Target-Macros" rel="up" title="Target Macros"> +<link href="Mode-Switching.html#Mode-Switching" rel="next" title="Mode Switching"> +<link href="BTF-Debug.html#BTF-Debug" rel="previous" title="BTF Debug"> +<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="Floating-Point"></a> +<div class="header"> +<p> +Next: <a href="Mode-Switching.html#Mode-Switching" accesskey="n" rel="next">Mode Switching</a>, Previous: <a href="Debugging-Info.html#Debugging-Info" accesskey="p" rel="previous">Debugging Info</a>, Up: <a href="Target-Macros.html#Target-Macros" accesskey="u" rel="up">Target Macros</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="Cross-Compilation-and-Floating-Point"></a> +<h3 class="section">18.22 Cross Compilation and Floating Point</h3> +<a name="index-cross-compilation-and-floating-point"></a> +<a name="index-floating-point-and-cross-compilation"></a> + +<p>While all modern machines use twos-complement representation for integers, +there are a variety of representations for floating point numbers. This +means that in a cross-compiler the representation of floating point numbers +in the compiled program may be different from that used in the machine +doing the compilation. +</p> +<p>Because different representation systems may offer different amounts of +range and precision, all floating point constants must be represented in +the target machine’s format. Therefore, the cross compiler cannot +safely use the host machine’s floating point arithmetic; it must emulate +the target’s arithmetic. To ensure consistency, GCC always uses +emulation to work with floating point values, even when the host and +target floating point formats are identical. +</p> +<p>The following macros are provided by <samp>real.h</samp> for the compiler to +use. All parts of the compiler which generate or optimize +floating-point calculations must use these macros. They may evaluate +their operands more than once, so operands must not have side effects. +</p> +<dl> +<dt><a name="index-REAL_005fVALUE_005fTYPE"></a>Macro: <strong>REAL_VALUE_TYPE</strong></dt> +<dd><p>The C data type to be used to hold a floating point value in the target +machine’s format. Typically this is a <code>struct</code> containing an +array of <code>HOST_WIDE_INT</code>, but all code should treat it as an opaque +quantity. +</p></dd></dl> + +<dl> +<dt><a name="index-REAL_005fVALUE_005fFIX"></a>Macro: <em>HOST_WIDE_INT</em> <strong>REAL_VALUE_FIX</strong> <em>(REAL_VALUE_TYPE <var>x</var>)</em></dt> +<dd><p>Truncates <var>x</var> to a signed integer, rounding toward zero. +</p></dd></dl> + +<dl> +<dt><a name="index-REAL_005fVALUE_005fUNSIGNED_005fFIX"></a>Macro: <em>unsigned HOST_WIDE_INT</em> <strong>REAL_VALUE_UNSIGNED_FIX</strong> <em>(REAL_VALUE_TYPE <var>x</var>)</em></dt> +<dd><p>Truncates <var>x</var> to an unsigned integer, rounding toward zero. If +<var>x</var> is negative, returns zero. +</p></dd></dl> + +<dl> +<dt><a name="index-REAL_005fVALUE_005fATOF"></a>Macro: <em>REAL_VALUE_TYPE</em> <strong>REAL_VALUE_ATOF</strong> <em>(const char *<var>string</var>, machine_mode <var>mode</var>)</em></dt> +<dd><p>Converts <var>string</var> into a floating point number in the target machine’s +representation for mode <var>mode</var>. This routine can handle both +decimal and hexadecimal floating point constants, using the syntax +defined by the C language for both. +</p></dd></dl> + +<dl> +<dt><a name="index-REAL_005fVALUE_005fNEGATIVE"></a>Macro: <em>int</em> <strong>REAL_VALUE_NEGATIVE</strong> <em>(REAL_VALUE_TYPE <var>x</var>)</em></dt> +<dd><p>Returns 1 if <var>x</var> is negative (including negative zero), 0 otherwise. +</p></dd></dl> + +<dl> +<dt><a name="index-REAL_005fVALUE_005fISINF"></a>Macro: <em>int</em> <strong>REAL_VALUE_ISINF</strong> <em>(REAL_VALUE_TYPE <var>x</var>)</em></dt> +<dd><p>Determines whether <var>x</var> represents infinity (positive or negative). +</p></dd></dl> + +<dl> +<dt><a name="index-REAL_005fVALUE_005fISNAN"></a>Macro: <em>int</em> <strong>REAL_VALUE_ISNAN</strong> <em>(REAL_VALUE_TYPE <var>x</var>)</em></dt> +<dd><p>Determines whether <var>x</var> represents a “NaN” (not-a-number). +</p></dd></dl> + +<dl> +<dt><a name="index-REAL_005fVALUE_005fNEGATE"></a>Macro: <em>REAL_VALUE_TYPE</em> <strong>REAL_VALUE_NEGATE</strong> <em>(REAL_VALUE_TYPE <var>x</var>)</em></dt> +<dd><p>Returns the negative of the floating point value <var>x</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-REAL_005fVALUE_005fABS"></a>Macro: <em>REAL_VALUE_TYPE</em> <strong>REAL_VALUE_ABS</strong> <em>(REAL_VALUE_TYPE <var>x</var>)</em></dt> +<dd><p>Returns the absolute value of <var>x</var>. +</p></dd></dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Mode-Switching.html#Mode-Switching" accesskey="n" rel="next">Mode Switching</a>, Previous: <a href="Debugging-Info.html#Debugging-Info" accesskey="p" rel="previous">Debugging Info</a>, Up: <a href="Target-Macros.html#Target-Macros" accesskey="u" rel="up">Target Macros</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> + + + +</body> +</html> |