| <!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) 1991-2013 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: s390 Operands</title> |
| |
| <meta name="description" content="Using as: s390 Operands"> |
| <meta name="keywords" content="Using as: s390 Operands"> |
| <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="s390-Syntax.html#s390-Syntax" rel="up" title="s390 Syntax"> |
| <link href="s390-Formats.html#s390-Formats" rel="next" title="s390 Formats"> |
| <link href="s390-Mnemonics.html#s390-Mnemonics" rel="prev" title="s390 Mnemonics"> |
| <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="s390-Operands"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="s390-Formats.html#s390-Formats" accesskey="n" rel="next">s390 Formats</a>, Previous: <a href="s390-Mnemonics.html#s390-Mnemonics" accesskey="p" rel="prev">s390 Mnemonics</a>, Up: <a href="s390-Syntax.html#s390-Syntax" accesskey="u" rel="up">s390 Syntax</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="Instruction-Operands"></a> |
| <h4 class="subsubsection">9.37.3.3 Instruction Operands</h4> |
| <a name="index-instruction-operands_002c-s390"></a> |
| <a name="index-s390-instruction-operands"></a> |
| |
| <p>Instruction operands can be grouped into three classes, operands located |
| in registers, immediate operands, and operands in storage. |
| </p> |
| <p>A register operand can be located in general, floating-point, access, |
| or control register. The register is identified by a four-bit field. |
| The field containing the register operand is called the R field. |
| </p> |
| <p>Immediate operands are contained within the instruction and can have |
| 8, 16 or 32 bits. The field containing the immediate operand is called |
| the I field. Dependent on the instruction the I field is either signed |
| or unsigned. |
| </p> |
| <p>A storage operand consists of an address and a length. The address of a |
| storage operands can be specified in any of these ways: |
| </p> |
| <ul> |
| <li> The content of a single general R |
| </li><li> The sum of the content of a general register called the base |
| register B plus the content of a displacement field D |
| </li><li> The sum of the contents of two general registers called the |
| index register X and the base register B plus the content of a |
| displacement field |
| </li><li> The sum of the current instruction address and a 32-bit signed |
| immediate field multiplied by two. |
| </li></ul> |
| |
| <p>The length of a storage operand can be: |
| </p> |
| <ul> |
| <li> Implied by the instruction |
| </li><li> Specified by a bitmask |
| </li><li> Specified by a four-bit or eight-bit length field L |
| </li><li> Specified by the content of a general register |
| </li></ul> |
| |
| <p>The notation for storage operand addresses formed from multiple fields is |
| as follows: |
| </p> |
| <dl compact="compact"> |
| <dt><code>Dn(Bn)</code></dt> |
| <dd><p>the address for operand number n is formed from the content of general |
| register Bn called the base register and the displacement field Dn. |
| </p></dd> |
| <dt><code>Dn(Xn,Bn)</code></dt> |
| <dd><p>the address for operand number n is formed from the content of general |
| register Xn called the index register, general register Bn called the |
| base register and the displacement field Dn. |
| </p></dd> |
| <dt><code>Dn(Ln,Bn)</code></dt> |
| <dd><p>the address for operand number n is formed from the content of general |
| regiser Bn called the base register and the displacement field Dn. |
| The length of the operand n is specified by the field Ln. |
| </p></dd> |
| </dl> |
| |
| <p>The base registers Bn and the index registers Xn of a storage operand can |
| be skipped. If Bn and Xn are skipped, a zero will be stored to the operand |
| field. The notation changes as follows: |
| </p> |
| <div class="display"> |
| <table> |
| <thead><tr><th width="30%"><pre class="display">full notation</pre></th><th width="30%"><pre class="display">short notation</pre></th></tr></thead> |
| <tr><td width="30%"><pre class="display">Dn(0,Bn)</pre></td><td width="30%"><pre class="display">Dn(Bn)</pre></td></tr> |
| <tr><td width="30%"><pre class="display">Dn(0,0)</pre></td><td width="30%"><pre class="display">Dn</pre></td></tr> |
| <tr><td width="30%"><pre class="display">Dn(0)</pre></td><td width="30%"><pre class="display">Dn</pre></td></tr> |
| <tr><td width="30%"><pre class="display">Dn(Ln,0)</pre></td><td width="30%"><pre class="display">Dn(Ln)</pre></td></tr> |
| </table> |
| </div> |
| |
| |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="s390-Formats.html#s390-Formats" accesskey="n" rel="next">s390 Formats</a>, Previous: <a href="s390-Mnemonics.html#s390-Mnemonics" accesskey="p" rel="prev">s390 Mnemonics</a>, Up: <a href="s390-Syntax.html#s390-Syntax" accesskey="u" rel="up">s390 Syntax</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> |
