134 lines
6.8 KiB
HTML
134 lines
6.8 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- This file documents the GNU Assembler "as".
|
|
|
|
Copyright (C) 1991-2016 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".
|
|
-->
|
|
<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>Using as: i386-Float</title>
|
|
|
|
<meta name="description" content="Using as: i386-Float">
|
|
<meta name="keywords" content="Using as: i386-Float">
|
|
<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="AS-Index.html#AS-Index" rel="index" title="AS Index">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="i386_002dDependent.html#i386_002dDependent" rel="up" title="i386-Dependent">
|
|
<link href="i386_002dSIMD.html#i386_002dSIMD" rel="next" title="i386-SIMD">
|
|
<link href="i386_002dJumps.html#i386_002dJumps" rel="prev" title="i386-Jumps">
|
|
<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="i386_002dFloat"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="i386_002dSIMD.html#i386_002dSIMD" accesskey="n" rel="next">i386-SIMD</a>, Previous: <a href="i386_002dJumps.html#i386_002dJumps" accesskey="p" rel="prev">i386-Jumps</a>, Up: <a href="i386_002dDependent.html#i386_002dDependent" accesskey="u" rel="up">i386-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<a name="Floating-Point-8"></a>
|
|
<h4 class="subsection">9.15.9 Floating Point</h4>
|
|
|
|
<a name="index-i386-floating-point"></a>
|
|
<a name="index-floating-point_002c-i386"></a>
|
|
<a name="index-x86_002d64-floating-point"></a>
|
|
<a name="index-floating-point_002c-x86_002d64"></a>
|
|
<p>All 80387 floating point types except packed BCD are supported.
|
|
(BCD support may be added without much difficulty). These data
|
|
types are 16-, 32-, and 64- bit integers, and single (32-bit),
|
|
double (64-bit), and extended (80-bit) precision floating point.
|
|
Each supported type has an instruction mnemonic suffix and a constructor
|
|
associated with it. Instruction mnemonic suffixes specify the operand’s
|
|
data type. Constructors build these data types into memory.
|
|
</p>
|
|
<a name="index-float-directive_002c-i386"></a>
|
|
<a name="index-single-directive_002c-i386"></a>
|
|
<a name="index-double-directive_002c-i386"></a>
|
|
<a name="index-tfloat-directive_002c-i386"></a>
|
|
<a name="index-float-directive_002c-x86_002d64"></a>
|
|
<a name="index-single-directive_002c-x86_002d64"></a>
|
|
<a name="index-double-directive_002c-x86_002d64"></a>
|
|
<a name="index-tfloat-directive_002c-x86_002d64"></a>
|
|
<ul>
|
|
<li> Floating point constructors are ‘<samp>.float</samp>’ or ‘<samp>.single</samp>’,
|
|
‘<samp>.double</samp>’, and ‘<samp>.tfloat</samp>’ for 32-, 64-, and 80-bit formats.
|
|
These correspond to instruction mnemonic suffixes ‘<samp>s</samp>’, ‘<samp>l</samp>’,
|
|
and ‘<samp>t</samp>’. ‘<samp>t</samp>’ stands for 80-bit (ten byte) real. The 80387
|
|
only supports this format via the ‘<samp>fldt</samp>’ (load 80-bit real to stack
|
|
top) and ‘<samp>fstpt</samp>’ (store 80-bit real and pop stack) instructions.
|
|
|
|
</li><li> <a name="index-word-directive_002c-i386"></a>
|
|
<a name="index-long-directive_002c-i386"></a>
|
|
<a name="index-int-directive_002c-i386"></a>
|
|
<a name="index-quad-directive_002c-i386"></a>
|
|
<a name="index-word-directive_002c-x86_002d64"></a>
|
|
<a name="index-long-directive_002c-x86_002d64"></a>
|
|
<a name="index-int-directive_002c-x86_002d64"></a>
|
|
<a name="index-quad-directive_002c-x86_002d64"></a>
|
|
Integer constructors are ‘<samp>.word</samp>’, ‘<samp>.long</samp>’ or ‘<samp>.int</samp>’, and
|
|
‘<samp>.quad</samp>’ for the 16-, 32-, and 64-bit integer formats. The
|
|
corresponding instruction mnemonic suffixes are ‘<samp>s</samp>’ (single),
|
|
‘<samp>l</samp>’ (long), and ‘<samp>q</samp>’ (quad). As with the 80-bit real format,
|
|
the 64-bit ‘<samp>q</samp>’ format is only present in the ‘<samp>fildq</samp>’ (load
|
|
quad integer to stack top) and ‘<samp>fistpq</samp>’ (store quad integer and pop
|
|
stack) instructions.
|
|
</li></ul>
|
|
|
|
<p>Register to register operations should not use instruction mnemonic suffixes.
|
|
‘<samp>fstl %st, %st(1)</samp>’ will give a warning, and be assembled as if you
|
|
wrote ‘<samp>fst %st, %st(1)</samp>’, since all register to register operations
|
|
use 80-bit floating point operands. (Contrast this with ‘<samp>fstl %st, mem</samp>’,
|
|
which converts ‘<samp>%st</samp>’ from 80-bit to 64-bit floating point format,
|
|
then stores the result in the 4 byte location ‘<samp>mem</samp>’)
|
|
</p>
|
|
<hr>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="i386_002dSIMD.html#i386_002dSIMD" accesskey="n" rel="next">i386-SIMD</a>, Previous: <a href="i386_002dJumps.html#i386_002dJumps" accesskey="p" rel="prev">i386-Jumps</a>, Up: <a href="i386_002dDependent.html#i386_002dDependent" accesskey="u" rel="up">i386-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|