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archived-ballistic/spec/arm64_xml/rev64_advsimd.xml
Ronald Caesar 26a677f8b4 decoder: Add ARM specification docs
Signed-off-by: Ronald Caesar <github43132@proton.me>
2025-12-12 18:11:36 -04:00

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<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet type="text/xsl" encoding="UTF-8" href="iform.xsl" version="1.0"?>
<!DOCTYPE instructionsection PUBLIC "-//ARM//DTD instructionsection //EN" "iform-p.dtd">
<!-- Copyright (c) 2010-2022 Arm Limited or its affiliates. All rights reserved. -->
<!-- This document is Non-Confidential. This document may only be used and distributed in accordance with the terms of the agreement entered into by Arm and the party that Arm delivered this document to. -->
<instructionsection id="REV64_advsimd" title="REV64 -- A64" type="instruction">
<docvars>
<docvar key="advsimd-type" value="simd" />
<docvar key="instr-class" value="advsimd" />
<docvar key="isa" value="A64" />
<docvar key="mnemonic" value="REV64" />
</docvars>
<heading>REV64</heading>
<desc>
<brief>
<para>Reverse elements in 64-bit doublewords (vector)</para>
</brief>
<authored>
<para>Reverse elements in 64-bit doublewords (vector). This instruction reverses the order of 8-bit, 16-bit, or 32-bit elements in each doubleword of the vector in the source SIMD&amp;FP register, places the results into a vector, and writes the vector to the destination SIMD&amp;FP register.</para>
<para>Depending on the settings in the <xref linkend="AArch64.cpacr_el1">CPACR_EL1</xref>, <xref linkend="AArch64.cptr_el2">CPTR_EL2</xref>, and <xref linkend="AArch64.cptr_el3">CPTR_EL3</xref> registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.</para>
</authored>
</desc>
<operationalnotes>
<para>If PSTATE.DIT is 1:</para>
<list type="unordered">
<listitem><content>The execution time of this instruction is independent of:<list type="unordered"><listitem><content>The values of the data supplied in any of its registers.</content></listitem><listitem><content>The values of the NZCV flags.</content></listitem></list></content></listitem>
<listitem><content>The response of this instruction to asynchronous exceptions does not vary based on:<list type="unordered"><listitem><content>The values of the data supplied in any of its registers.</content></listitem><listitem><content>The values of the NZCV flags.</content></listitem></list></content></listitem>
</list>
</operationalnotes>
<alias_list howmany="0"></alias_list>
<classes>
<iclass name="Vector" oneof="1" id="iclass_simd" no_encodings="1" isa="A64">
<docvars>
<docvar key="advsimd-type" value="simd" />
<docvar key="instr-class" value="advsimd" />
<docvar key="isa" value="A64" />
<docvar key="mnemonic" value="REV64" />
</docvars>
<iclassintro count="1"></iclassintro>
<regdiagram form="32" psname="aarch64/instrs/vector/arithmetic/unary/rev" tworows="1">
<box hibit="31" settings="1">
<c>0</c>
</box>
<box hibit="30" name="Q" usename="1">
<c></c>
</box>
<box hibit="29" name="U" usename="1" settings="1" psbits="x">
<c>0</c>
</box>
<box hibit="28" width="5" settings="5">
<c>0</c>
<c>1</c>
<c>1</c>
<c>1</c>
<c>0</c>
</box>
<box hibit="23" width="2" name="size" usename="1">
<c colspan="2"></c>
</box>
<box hibit="21" width="5" settings="5">
<c>1</c>
<c>0</c>
<c>0</c>
<c>0</c>
<c>0</c>
</box>
<box hibit="16" width="4" name="opcode[4:1]" settings="4">
<c>0</c>
<c>0</c>
<c>0</c>
<c>0</c>
</box>
<box hibit="12" name="o0" usename="1" settings="1" psbits="x">
<c>0</c>
</box>
<box hibit="11" width="2" settings="2">
<c>1</c>
<c>0</c>
</box>
<box hibit="9" width="5" name="Rn" usename="1">
<c colspan="5"></c>
</box>
<box hibit="4" width="5" name="Rd" usename="1">
<c colspan="5"></c>
</box>
</regdiagram>
<encoding name="REV64_asimdmisc_R" oneofinclass="1" oneof="1" label="">
<docvars>
<docvar key="advsimd-type" value="simd" />
<docvar key="instr-class" value="advsimd" />
<docvar key="isa" value="A64" />
<docvar key="mnemonic" value="REV64" />
</docvars>
<asmtemplate><text>REV64 </text><a link="sa_vd" hover="SIMD&amp;FP destination register (field &quot;Rd&quot;)">&lt;Vd&gt;</a><text>.</text><a link="sa_t" hover="Arrangement specifier (field &quot;size:Q&quot;) [2S,4H,4S,8B,8H,16B]">&lt;T&gt;</a><text>, </text><a link="sa_vn" hover="SIMD&amp;FP source register (field &quot;Rn&quot;)">&lt;Vn&gt;</a><text>.</text><a link="sa_t" hover="Arrangement specifier (field &quot;size:Q&quot;) [2S,4H,4S,8B,8H,16B]">&lt;T&gt;</a></asmtemplate>
</encoding>
<ps_section howmany="1">
<ps name="aarch64/instrs/vector/arithmetic/unary/rev" mylink="aarch64.instrs.vector.arithmetic.unary.rev" enclabels="" sections="1" secttype="noheading">
<pstext mayhavelinks="1" section="Decode" rep_section="decode">integer d = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rd);
integer n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn);
// size=esize: B(0), H(1), S(1), D(S)
integer esize = 8 &lt;&lt; <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(size);
integer datasize = if Q == '1' then 128 else 64;
// op=REVx: 64(0), 32(1), 16(2)
bits(2) op = o0:U;
// =&gt; op+size:
// 64+B = 0, 64+H = 1, 64+S = 2, 64+D = X
// 32+B = 1, 32+H = 2, 32+S = X, 32+D = X
// 16+B = 2, 16+H = X, 16+S = X, 16+D = X
// 8+B = X, 8+H = X, 8+S = X, 8+D = X
// =&gt; 3-(op+size) (index bits in group)
// 64/B = 3, 64+H = 2, 64+S = 1, 64+D = X
// 32+B = 2, 32+H = 1, 32+S = X, 32+D = X
// 16+B = 1, 16+H = X, 16+S = X, 16+D = X
// 8+B = X, 8+H = X, 8+S = X, 8+D = X
// index bits within group: 1, 2, 3
if <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(op)+<a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(size) &gt;= 3 then UNDEFINED;
integer container_size;
case op of
when '10' container_size = 16;
when '01' container_size = 32;
when '00' container_size = 64;
integer containers = datasize DIV container_size;
integer elements_per_container = container_size DIV esize;</pstext>
</ps>
</ps_section>
</iclass>
</classes>
<explanations scope="all">
<explanation enclist="REV64_asimdmisc_R" symboldefcount="1">
<symbol link="sa_vd">&lt;Vd&gt;</symbol>
<account encodedin="Rd">
<intro>
<para>Is the name of the SIMD&amp;FP destination register, encoded in the "Rd" field.</para>
</intro>
</account>
</explanation>
<explanation enclist="REV64_asimdmisc_R" symboldefcount="1">
<symbol link="sa_t">&lt;T&gt;</symbol>
<definition encodedin="size:Q">
<intro>Is an arrangement specifier, </intro>
<table class="valuetable">
<tgroup cols="3">
<thead>
<row>
<entry class="bitfield">size</entry>
<entry class="bitfield">Q</entry>
<entry class="symbol">&lt;T&gt;</entry>
</row>
</thead>
<tbody>
<row>
<entry class="bitfield">00</entry>
<entry class="bitfield">0</entry>
<entry class="symbol">8B</entry>
</row>
<row>
<entry class="bitfield">00</entry>
<entry class="bitfield">1</entry>
<entry class="symbol">16B</entry>
</row>
<row>
<entry class="bitfield">01</entry>
<entry class="bitfield">0</entry>
<entry class="symbol">4H</entry>
</row>
<row>
<entry class="bitfield">01</entry>
<entry class="bitfield">1</entry>
<entry class="symbol">8H</entry>
</row>
<row>
<entry class="bitfield">10</entry>
<entry class="bitfield">0</entry>
<entry class="symbol">2S</entry>
</row>
<row>
<entry class="bitfield">10</entry>
<entry class="bitfield">1</entry>
<entry class="symbol">4S</entry>
</row>
<row>
<entry class="bitfield">11</entry>
<entry class="bitfield">x</entry>
<entry class="symbol">RESERVED</entry>
</row>
</tbody>
</tgroup>
</table>
</definition>
</explanation>
<explanation enclist="REV64_asimdmisc_R" symboldefcount="1">
<symbol link="sa_vn">&lt;Vn&gt;</symbol>
<account encodedin="Rn">
<intro>
<para>Is the name of the SIMD&amp;FP source register, encoded in the "Rn" field.</para>
</intro>
</account>
</explanation>
</explanations>
<ps_section howmany="1">
<ps name="aarch64/instrs/vector/arithmetic/unary/rev" mylink="execute" enclabels="" sections="1" secttype="Operation">
<pstext mayhavelinks="1" section="Execute" rep_section="execute"><a link="impl-aarch64.CheckFPAdvSIMDEnabled64.0" file="shared_pseudocode.xml" hover="function: CheckFPAdvSIMDEnabled64()">CheckFPAdvSIMDEnabled64</a>();
bits(datasize) operand = <a link="impl-aarch64.V.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) V[integer n, integer width]">V</a>[n, datasize];
bits(datasize) result;
integer element = 0;
integer rev_element;
for c = 0 to containers-1
rev_element = (element + elements_per_container) - 1;
for e = 0 to elements_per_container-1
<a link="impl-shared.Elem.write.3" file="shared_pseudocode.xml" hover="accessor: Elem[bits(N) &amp;vector, integer e, integer size] = bits(size) value">Elem</a>[result, rev_element, esize] = <a link="impl-shared.Elem.read.3" file="shared_pseudocode.xml" hover="accessor: bits(size) Elem[bits(N) vector, integer e, integer size]">Elem</a>[operand, element, esize];
element = element + 1;
rev_element = rev_element - 1;
<a link="impl-aarch64.V.write.2" file="shared_pseudocode.xml" hover="accessor: V[integer n, integer width] = bits(width) value">V</a>[d, datasize] = result;</pstext>
</ps>
</ps_section>
</instructionsection>