You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
104 lines
4.6 KiB
HTML
104 lines
4.6 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>Flonums - Using as</title>
|
|
<meta http-equiv="Content-Type" content="text/html">
|
|
<meta name="description" content="Using as">
|
|
<meta name="generator" content="makeinfo 4.13">
|
|
<link title="Top" rel="start" href="index.html#Top">
|
|
<link rel="up" href="Numbers.html#Numbers" title="Numbers">
|
|
<link rel="prev" href="Bignums.html#Bignums" title="Bignums">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
This file documents the GNU Assembler "as".
|
|
|
|
Copyright (C) 1991-2015 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 no Invariant Sections, with no Front-Cover Texts, and with no
|
|
Back-Cover Texts. A copy of the license is included in the
|
|
section entitled ``GNU Free Documentation License''.
|
|
|
|
-->
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
|
<style type="text/css"><!--
|
|
pre.display { font-family:inherit }
|
|
pre.format { font-family:inherit }
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
|
pre.smallexample { font-size:smaller }
|
|
pre.smalllisp { font-size:smaller }
|
|
span.sc { font-variant:small-caps }
|
|
span.roman { font-family:serif; font-weight:normal; }
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
<div class="node">
|
|
<a name="Flonums"></a>
|
|
<p>
|
|
Previous: <a rel="previous" accesskey="p" href="Bignums.html#Bignums">Bignums</a>,
|
|
Up: <a rel="up" accesskey="u" href="Numbers.html#Numbers">Numbers</a>
|
|
<hr>
|
|
</div>
|
|
|
|
<h5 class="subsubsection">3.6.2.3 Flonums</h5>
|
|
|
|
<p><a name="index-flonums-181"></a><a name="index-floating-point-numbers-182"></a><a name="index-constants_002c-floating-point-183"></a>
|
|
<a name="index-precision_002c-floating-point-184"></a>A <dfn>flonum</dfn> represents a floating point number. The translation is
|
|
indirect: a decimal floating point number from the text is converted by
|
|
<samp><span class="command">as</span></samp> to a generic binary floating point number of more than
|
|
sufficient precision. This generic floating point number is converted
|
|
to a particular computer's floating point format (or formats) by a
|
|
portion of <samp><span class="command">as</span></samp> specialized to that computer.
|
|
|
|
<p>A flonum is written by writing (in order)
|
|
<ul>
|
|
<li>The digit ‘<samp><span class="samp">0</span></samp>’.
|
|
(‘<samp><span class="samp">0</span></samp>’ is optional on the HPPA.)
|
|
|
|
<li>A letter, to tell <samp><span class="command">as</span></samp> the rest of the number is a flonum.
|
|
<kbd>e</kbd> is recommended. Case is not important.
|
|
|
|
<p>On the H8/300, Renesas / SuperH SH,
|
|
and AMD 29K architectures, the letter must be
|
|
one of the letters ‘<samp><span class="samp">DFPRSX</span></samp>’ (in upper or lower case).
|
|
|
|
<p>On the ARC, the letter must be one of the letters ‘<samp><span class="samp">DFRS</span></samp>’
|
|
(in upper or lower case).
|
|
|
|
<p>On the Intel 960 architecture, the letter must be
|
|
one of the letters ‘<samp><span class="samp">DFT</span></samp>’ (in upper or lower case).
|
|
|
|
<p>On the HPPA architecture, the letter must be ‘<samp><span class="samp">E</span></samp>’ (upper case only).
|
|
|
|
<li>An optional sign: either ‘<samp><span class="samp">+</span></samp>’ or ‘<samp><span class="samp">-</span></samp>’.
|
|
|
|
<li>An optional <dfn>integer part</dfn>: zero or more decimal digits.
|
|
|
|
<li>An optional <dfn>fractional part</dfn>: ‘<samp><span class="samp">.</span></samp>’ followed by zero
|
|
or more decimal digits.
|
|
|
|
<li>An optional exponent, consisting of:
|
|
|
|
<ul>
|
|
<li>An ‘<samp><span class="samp">E</span></samp>’ or ‘<samp><span class="samp">e</span></samp>’.
|
|
<!-- I can't find a config where "EXP_CHARS" is other than 'eE', but in -->
|
|
<!-- principle this can perfectly well be different on different targets. -->
|
|
<li>Optional sign: either ‘<samp><span class="samp">+</span></samp>’ or ‘<samp><span class="samp">-</span></samp>’.
|
|
<li>One or more decimal digits.
|
|
</ul>
|
|
|
|
</ul>
|
|
|
|
<p>At least one of the integer part or the fractional part must be
|
|
present. The floating point number has the usual base-10 value.
|
|
|
|
<p><samp><span class="command">as</span></samp> does all processing using integers. Flonums are computed
|
|
independently of any floating point hardware in the computer running
|
|
<samp><span class="command">as</span></samp>.
|
|
|
|
</body></html>
|
|
|