1<html lang="en"> 2<head> 3<title>Fixed-Point - Using the GNU Compiler Collection (GCC)</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Using the GNU Compiler Collection (GCC)"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="C-Extensions.html#C-Extensions" title="C Extensions"> 9<link rel="prev" href="Hex-Floats.html#Hex-Floats" title="Hex Floats"> 10<link rel="next" href="Named-Address-Spaces.html#Named-Address-Spaces" title="Named Address Spaces"> 11<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 12<!-- 13Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 141998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 152010 Free Software Foundation, Inc. 16 17Permission is granted to copy, distribute and/or modify this document 18under the terms of the GNU Free Documentation License, Version 1.3 or 19any later version published by the Free Software Foundation; with the 20Invariant Sections being ``Funding Free Software'', the Front-Cover 21Texts being (a) (see below), and with the Back-Cover Texts being (b) 22(see below). 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Support for fixed-point 64types in GCC will evolve as the draft technical report changes. 65Calling conventions for any target might also change. Not all targets 66support fixed-point types. 67 68 <p>The fixed-point types are 69<code>short _Fract</code>, 70<code>_Fract</code>, 71<code>long _Fract</code>, 72<code>long long _Fract</code>, 73<code>unsigned short _Fract</code>, 74<code>unsigned _Fract</code>, 75<code>unsigned long _Fract</code>, 76<code>unsigned long long _Fract</code>, 77<code>_Sat short _Fract</code>, 78<code>_Sat _Fract</code>, 79<code>_Sat long _Fract</code>, 80<code>_Sat long long _Fract</code>, 81<code>_Sat unsigned short _Fract</code>, 82<code>_Sat unsigned _Fract</code>, 83<code>_Sat unsigned long _Fract</code>, 84<code>_Sat unsigned long long _Fract</code>, 85<code>short _Accum</code>, 86<code>_Accum</code>, 87<code>long _Accum</code>, 88<code>long long _Accum</code>, 89<code>unsigned short _Accum</code>, 90<code>unsigned _Accum</code>, 91<code>unsigned long _Accum</code>, 92<code>unsigned long long _Accum</code>, 93<code>_Sat short _Accum</code>, 94<code>_Sat _Accum</code>, 95<code>_Sat long _Accum</code>, 96<code>_Sat long long _Accum</code>, 97<code>_Sat unsigned short _Accum</code>, 98<code>_Sat unsigned _Accum</code>, 99<code>_Sat unsigned long _Accum</code>, 100<code>_Sat unsigned long long _Accum</code>. 101 102 <p>Fixed-point data values contain fractional and optional integral parts. 103The format of fixed-point data varies and depends on the target machine. 104 105 <p>Support for fixed-point types includes: 106 <ul> 107<li>prefix and postfix increment and decrement operators (<code>++</code>, <code>--</code>) 108<li>unary arithmetic operators (<code>+</code>, <code>-</code>, <code>!</code>) 109<li>binary arithmetic operators (<code>+</code>, <code>-</code>, <code>*</code>, <code>/</code>) 110<li>binary shift operators (<code><<</code>, <code>>></code>) 111<li>relational operators (<code><</code>, <code><=</code>, <code>>=</code>, <code>></code>) 112<li>equality operators (<code>==</code>, <code>!=</code>) 113<li>assignment operators (<code>+=</code>, <code>-=</code>, <code>*=</code>, <code>/=</code>, 114<code><<=</code>, <code>>>=</code>) 115<li>conversions to and from integer, floating-point, or fixed-point types 116</ul> 117 118 <p>Use a suffix in a fixed-point literal constant: 119 <ul> 120<li>‘<samp><span class="samp">hr</span></samp>’ or ‘<samp><span class="samp">HR</span></samp>’ for <code>short _Fract</code> and 121<code>_Sat short _Fract</code> 122<li>‘<samp><span class="samp">r</span></samp>’ or ‘<samp><span class="samp">R</span></samp>’ for <code>_Fract</code> and <code>_Sat _Fract</code> 123<li>‘<samp><span class="samp">lr</span></samp>’ or ‘<samp><span class="samp">LR</span></samp>’ for <code>long _Fract</code> and 124<code>_Sat long _Fract</code> 125<li>‘<samp><span class="samp">llr</span></samp>’ or ‘<samp><span class="samp">LLR</span></samp>’ for <code>long long _Fract</code> and 126<code>_Sat long long _Fract</code> 127<li>‘<samp><span class="samp">uhr</span></samp>’ or ‘<samp><span class="samp">UHR</span></samp>’ for <code>unsigned short _Fract</code> and 128<code>_Sat unsigned short _Fract</code> 129<li>‘<samp><span class="samp">ur</span></samp>’ or ‘<samp><span class="samp">UR</span></samp>’ for <code>unsigned _Fract</code> and 130<code>_Sat unsigned _Fract</code> 131<li>‘<samp><span class="samp">ulr</span></samp>’ or ‘<samp><span class="samp">ULR</span></samp>’ for <code>unsigned long _Fract</code> and 132<code>_Sat unsigned long _Fract</code> 133<li>‘<samp><span class="samp">ullr</span></samp>’ or ‘<samp><span class="samp">ULLR</span></samp>’ for <code>unsigned long long _Fract</code> 134and <code>_Sat unsigned long long _Fract</code> 135<li>‘<samp><span class="samp">hk</span></samp>’ or ‘<samp><span class="samp">HK</span></samp>’ for <code>short _Accum</code> and 136<code>_Sat short _Accum</code> 137<li>‘<samp><span class="samp">k</span></samp>’ or ‘<samp><span class="samp">K</span></samp>’ for <code>_Accum</code> and <code>_Sat _Accum</code> 138<li>‘<samp><span class="samp">lk</span></samp>’ or ‘<samp><span class="samp">LK</span></samp>’ for <code>long _Accum</code> and 139<code>_Sat long _Accum</code> 140<li>‘<samp><span class="samp">llk</span></samp>’ or ‘<samp><span class="samp">LLK</span></samp>’ for <code>long long _Accum</code> and 141<code>_Sat long long _Accum</code> 142<li>‘<samp><span class="samp">uhk</span></samp>’ or ‘<samp><span class="samp">UHK</span></samp>’ for <code>unsigned short _Accum</code> and 143<code>_Sat unsigned short _Accum</code> 144<li>‘<samp><span class="samp">uk</span></samp>’ or ‘<samp><span class="samp">UK</span></samp>’ for <code>unsigned _Accum</code> and 145<code>_Sat unsigned _Accum</code> 146<li>‘<samp><span class="samp">ulk</span></samp>’ or ‘<samp><span class="samp">ULK</span></samp>’ for <code>unsigned long _Accum</code> and 147<code>_Sat unsigned long _Accum</code> 148<li>‘<samp><span class="samp">ullk</span></samp>’ or ‘<samp><span class="samp">ULLK</span></samp>’ for <code>unsigned long long _Accum</code> 149and <code>_Sat unsigned long long _Accum</code> 150</ul> 151 152 <p>GCC support of fixed-point types as specified by the draft technical report 153is incomplete: 154 155 <ul> 156<li>Pragmas to control overflow and rounding behaviors are not implemented. 157</ul> 158 159 <p>Fixed-point types are supported by the DWARF2 debug information format. 160 161 </body></html> 162 163