134 lines
6.1 KiB
HTML
134 lines
6.1 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- This file documents the GNU Assembler "as".
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Copyright (C) 1991-2016 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, with no Front-Cover Texts, and with no
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Back-Cover Texts. A copy of the license is included in the
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section entitled "GNU Free Documentation License".
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-->
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Using as: ESA/390 Syntax</title>
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<meta name="description" content="Using as: ESA/390 Syntax">
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<meta name="keywords" content="Using as: ESA/390 Syntax">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="AS-Index.html#AS-Index" rel="index" title="AS Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="ESA_002f390_002dDependent.html#ESA_002f390_002dDependent" rel="up" title="ESA/390-Dependent">
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<link href="ESA_002f390-Floating-Point.html#ESA_002f390-Floating-Point" rel="next" title="ESA/390 Floating Point">
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<link href="ESA_002f390-Options.html#ESA_002f390-Options" rel="prev" title="ESA/390 Options">
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<style type="text/css">
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-->
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</style>
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="ESA_002f390-Syntax"></a>
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<div class="header">
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<p>
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Next: <a href="ESA_002f390-Floating-Point.html#ESA_002f390-Floating-Point" accesskey="n" rel="next">ESA/390 Floating Point</a>, Previous: <a href="ESA_002f390-Options.html#ESA_002f390-Options" accesskey="p" rel="prev">ESA/390 Options</a>, Up: <a href="ESA_002f390_002dDependent.html#ESA_002f390_002dDependent" accesskey="u" rel="up">ESA/390-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>
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</div>
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<hr>
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<a name="Syntax-13"></a>
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<h4 class="subsection">9.14.3 Syntax</h4>
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<p>The opcode/operand syntax follows the ESA/390 Principles of Operation
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manual; assembler directives and general syntax are loosely based on the
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prevailing AT&T/SVR4/ELF/Solaris style notation. HLASM-style directives
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are <em>not</em> supported for the most part, with the exception of those
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described herein.
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</p>
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<p>A leading dot in front of directives is optional, and the case of
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directives is ignored; thus for example, .using and USING have the same
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effect.
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</p>
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<p>A colon may immediately follow a label definition. This is
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simply for compatibility with how most assembly language programmers
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write code.
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</p>
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<p>‘<samp>#</samp>’ is the line comment character.
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</p>
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<p>‘<samp>;</samp>’ can be used instead of a newline to separate statements.
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</p>
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<p>Since ‘<samp>$</samp>’ has no special meaning, you may use it in symbol names.
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</p>
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<p>Registers can be given the symbolic names r0..r15, fp0, fp2, fp4, fp6.
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By using thesse symbolic names, <code>as</code> can detect simple
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syntax errors. The name rarg or r.arg is a synonym for r11, rtca or r.tca
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for r12, sp, r.sp, dsa r.dsa for r13, lr or r.lr for r14, rbase or r.base
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for r3 and rpgt or r.pgt for r4.
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</p>
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<p>‘<samp>*</samp>’ is the current location counter. Unlike ‘<samp>.</samp>’ it is always
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relative to the last USING directive. Note that this means that
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expressions cannot use multiplication, as any occurrence of ‘<samp>*</samp>’
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will be interpreted as a location counter.
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</p>
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<p>All labels are relative to the last USING. Thus, branches to a label
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always imply the use of base+displacement.
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</p>
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<p>Many of the usual forms of address constants / address literals
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are supported. Thus,
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</p><div class="example">
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<pre class="example"> .using *,r3
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L r15,=A(some_routine)
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LM r6,r7,=V(some_longlong_extern)
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A r1,=F'12'
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AH r0,=H'42'
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ME r6,=E'3.1416'
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MD r6,=D'3.14159265358979'
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O r6,=XL4'cacad0d0'
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.ltorg
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</pre></div>
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<p>should all behave as expected: that is, an entry in the literal
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pool will be created (or reused if it already exists), and the
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instruction operands will be the displacement into the literal pool
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using the current base register (as last declared with the <code>.using</code>
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directive).
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</p>
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<hr>
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<div class="header">
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<p>
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Next: <a href="ESA_002f390-Floating-Point.html#ESA_002f390-Floating-Point" accesskey="n" rel="next">ESA/390 Floating Point</a>, Previous: <a href="ESA_002f390-Options.html#ESA_002f390-Options" accesskey="p" rel="prev">ESA/390 Options</a>, Up: <a href="ESA_002f390_002dDependent.html#ESA_002f390_002dDependent" accesskey="u" rel="up">ESA/390-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>
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</div>
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</body>
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</html>
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