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A copy of the license is included in the section entitled "GNU Free Documentation License". --> <!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ --> <head> <title>s390 Formats (Using as)</title> <meta name="description" content="s390 Formats (Using as)"> <meta name="keywords" content="s390 Formats (Using as)"> <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-Aliases.html#s390-Aliases" rel="next" title="s390 Aliases"> <link href="s390-Operands.html#s390-Operands" rel="prev" title="s390 Operands"> <style type="text/css"> <!-- a.summary-letter {text-decoration: none} blockquote.indentedblock {margin-right: 0em} blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} blockquote.smallquotation {font-size: smaller} div.display {margin-left: 3.2em} div.example {margin-left: 3.2em} div.lisp {margin-left: 3.2em} div.smalldisplay {margin-left: 3.2em} div.smallexample {margin-left: 3.2em} 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.nolinebreak {white-space: nowrap} span.roman {font-family: initial; font-weight: normal} span.sansserif {font-family: sans-serif; font-weight: normal} ul.no-bullet {list-style: none} --> </style> </head> <body lang="en"> <a name="s390-Formats"></a> <div class="header"> <p> Next: <a href="s390-Aliases.html#s390-Aliases" accesskey="n" rel="next">s390 Aliases</a>, Previous: <a href="s390-Operands.html#s390-Operands" accesskey="p" rel="prev">s390 Operands</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-Formats-1"></a> <h4 class="subsubsection">9.40.3.4 Instruction Formats</h4> <a name="index-instruction-formats_002c-s390"></a> <a name="index-s390-instruction-formats"></a> <p>The Principles of Operation manuals lists 26 instruction formats where some of the formats have multiple variants. For the ‘<samp>.insn</samp>’ pseudo directive the assembler recognizes some of the formats. Typically, the most general variant of the instruction format is used by the ‘<samp>.insn</samp>’ directive. </p> <p>The following table lists the abbreviations used in the table of instruction formats: </p> <div class="display"> <table> <tr><td><pre class="display">OpCode / OpCd</pre></td><td><pre class="display">Part of the op code.</pre></td></tr> <tr><td><pre class="display">Bx</pre></td><td><pre class="display">Base register number for operand x.</pre></td></tr> <tr><td><pre class="display">Dx</pre></td><td><pre class="display">Displacement for operand x.</pre></td></tr> <tr><td><pre class="display">DLx</pre></td><td><pre class="display">Displacement lower 12 bits for operand x.</pre></td></tr> <tr><td><pre class="display">DHx</pre></td><td><pre class="display">Displacement higher 8-bits for operand x.</pre></td></tr> <tr><td><pre class="display">Rx</pre></td><td><pre class="display">Register number for operand x.</pre></td></tr> <tr><td><pre class="display">Xx</pre></td><td><pre class="display">Index register number for operand x.</pre></td></tr> <tr><td><pre class="display">Ix</pre></td><td><pre class="display">Signed immediate for operand x.</pre></td></tr> <tr><td><pre class="display">Ux</pre></td><td><pre class="display">Unsigned immediate for operand x.</pre></td></tr> </table> </div> <p>An instruction is two, four, or six bytes in length and must be aligned on a 2 byte boundary. The first two bits of the instruction specify the length of the instruction, 00 indicates a two byte instruction, 01 and 10 indicates a four byte instruction, and 11 indicates a six byte instruction. </p> <p>The following table lists the s390 instruction formats that are available with the ‘<samp>.insn</samp>’ pseudo directive: </p> <dl compact="compact"> <dt><code>E format</code></dt> <dd><pre class="verbatim">+-------------+ | OpCode | +-------------+ 0 15 </pre> </dd> <dt><code>RI format: <insn> R1,I2</code></dt> <dd><pre class="verbatim">+--------+----+----+------------------+ | OpCode | R1 |OpCd| I2 | +--------+----+----+------------------+ 0 8 12 16 31 </pre> </dd> <dt><code>RIE format: <insn> R1,R3,I2</code></dt> <dd><pre class="verbatim">+--------+----+----+------------------+--------+--------+ | OpCode | R1 | R3 | I2 |////////| OpCode | +--------+----+----+------------------+--------+--------+ 0 8 12 16 32 40 47 </pre> </dd> <dt><code>RIL format: <insn> R1,I2</code></dt> <dd><pre class="verbatim">+--------+----+----+------------------------------------+ | OpCode | R1 |OpCd| I2 | +--------+----+----+------------------------------------+ 0 8 12 16 47 </pre> </dd> <dt><code>RILU format: <insn> R1,U2</code></dt> <dd><pre class="verbatim">+--------+----+----+------------------------------------+ | OpCode | R1 |OpCd| U2 | +--------+----+----+------------------------------------+ 0 8 12 16 47 </pre> </dd> <dt><code>RIS format: <insn> R1,I2,M3,D4(B4)</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+--------+--------+ | OpCode | R1 | M3 | B4 | D4 | I2 | Opcode | +--------+----+----+----+-------------+--------+--------+ 0 8 12 16 20 32 36 47 </pre> </dd> <dt><code>RR format: <insn> R1,R2</code></dt> <dd><pre class="verbatim">+--------+----+----+ | OpCode | R1 | R2 | +--------+----+----+ 0 8 12 15 </pre> </dd> <dt><code>RRE format: <insn> R1,R2</code></dt> <dd><pre class="verbatim">+------------------+--------+----+----+ | OpCode |////////| R1 | R2 | +------------------+--------+----+----+ 0 16 24 28 31 </pre> </dd> <dt><code>RRF format: <insn> R1,R2,R3,M4</code></dt> <dd><pre class="verbatim">+------------------+----+----+----+----+ | OpCode | R3 | M4 | R1 | R2 | +------------------+----+----+----+----+ 0 16 20 24 28 31 </pre> </dd> <dt><code>RRS format: <insn> R1,R2,M3,D4(B4)</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+----+----+--------+ | OpCode | R1 | R3 | B4 | D4 | M3 |////| OpCode | +--------+----+----+----+-------------+----+----+--------+ 0 8 12 16 20 32 36 40 47 </pre> </dd> <dt><code>RS format: <insn> R1,R3,D2(B2)</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+ | OpCode | R1 | R3 | B2 | D2 | +--------+----+----+----+-------------+ 0 8 12 16 20 31 </pre> </dd> <dt><code>RSE format: <insn> R1,R3,D2(B2)</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+--------+--------+ | OpCode | R1 | R3 | B2 | D2 |////////| OpCode | +--------+----+----+----+-------------+--------+--------+ 0 8 12 16 20 32 40 47 </pre> </dd> <dt><code>RSI format: <insn> R1,R3,I2</code></dt> <dd><pre class="verbatim">+--------+----+----+------------------------------------+ | OpCode | R1 | R3 | I2 | +--------+----+----+------------------------------------+ 0 8 12 16 47 </pre> </dd> <dt><code>RSY format: <insn> R1,R3,D2(B2)</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+--------+--------+ | OpCode | R1 | R3 | B2 | DL2 | DH2 | OpCode | +--------+----+----+----+-------------+--------+--------+ 0 8 12 16 20 32 40 47 </pre> </dd> <dt><code>RX format: <insn> R1,D2(X2,B2)</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+ | OpCode | R1 | X2 | B2 | D2 | +--------+----+----+----+-------------+ 0 8 12 16 20 31 </pre> </dd> <dt><code>RXE format: <insn> R1,D2(X2,B2)</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+--------+--------+ | OpCode | R1 | X2 | B2 | D2 |////////| OpCode | +--------+----+----+----+-------------+--------+--------+ 0 8 12 16 20 32 40 47 </pre> </dd> <dt><code>RXF format: <insn> R1,R3,D2(X2,B2)</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+----+---+--------+ | OpCode | R3 | X2 | B2 | D2 | R1 |///| OpCode | +--------+----+----+----+-------------+----+---+--------+ 0 8 12 16 20 32 36 40 47 </pre> </dd> <dt><code>RXY format: <insn> R1,D2(X2,B2)</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+--------+--------+ | OpCode | R1 | X2 | B2 | DL2 | DH2 | OpCode | +--------+----+----+----+-------------+--------+--------+ 0 8 12 16 20 32 36 40 47 </pre> </dd> <dt><code>S format: <insn> D2(B2)</code></dt> <dd><pre class="verbatim">+------------------+----+-------------+ | OpCode | B2 | D2 | +------------------+----+-------------+ 0 16 20 31 </pre> </dd> <dt><code>SI format: <insn> D1(B1),I2</code></dt> <dd><pre class="verbatim">+--------+---------+----+-------------+ | OpCode | I2 | B1 | D1 | +--------+---------+----+-------------+ 0 8 16 20 31 </pre> </dd> <dt><code>SIY format: <insn> D1(B1),U2</code></dt> <dd><pre class="verbatim">+--------+---------+----+-------------+--------+--------+ | OpCode | I2 | B1 | DL1 | DH1 | OpCode | +--------+---------+----+-------------+--------+--------+ 0 8 16 20 32 36 40 47 </pre> </dd> <dt><code>SIL format: <insn> D1(B1),I2</code></dt> <dd><pre class="verbatim">+------------------+----+-------------+-----------------+ | OpCode | B1 | D1 | I2 | +------------------+----+-------------+-----------------+ 0 16 20 32 47 </pre> </dd> <dt><code>SS format: <insn> D1(R1,B1),D2(B3),R3</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+----+------------+ | OpCode | R1 | R3 | B1 | D1 | B2 | D2 | +--------+----+----+----+-------------+----+------------+ 0 8 12 16 20 32 36 47 </pre> </dd> <dt><code>SSE format: <insn> D1(B1),D2(B2)</code></dt> <dd><pre class="verbatim">+------------------+----+-------------+----+------------+ | OpCode | B1 | D1 | B2 | D2 | +------------------+----+-------------+----+------------+ 0 8 12 16 20 32 36 47 </pre> </dd> <dt><code>SSF format: <insn> D1(B1),D2(B2),R3</code></dt> <dd><pre class="verbatim">+--------+----+----+----+-------------+----+------------+ | OpCode | R3 |OpCd| B1 | D1 | B2 | D2 | +--------+----+----+----+-------------+----+------------+ 0 8 12 16 20 32 36 47 </pre> </dd> </dl> <p>For the complete list of all instruction format variants see the Principles of Operation manuals. </p> <hr> <div class="header"> <p> Next: <a href="s390-Aliases.html#s390-Aliases" accesskey="n" rel="next">s390 Aliases</a>, Previous: <a href="s390-Operands.html#s390-Operands" accesskey="p" rel="prev">s390 Operands</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 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