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archived-ballistic/spec/arm64_xml/urshr_z_p_zi.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="urshr_z_p_zi" title="URSHR" type="instruction">
<docvars>
<docvar key="instr-class" value="sve2" />
<docvar key="isa" value="A64" />
<docvar key="mnemonic" value="URSHR" />
</docvars>
<heading>URSHR</heading>
<desc>
<brief>Unsigned rounding shift right by immediate</brief>
<description>
<para>Shift right by immediate each active unsigned element of the source vector, and destructively place the rounded results in the corresponding elements of the source vector. The immediate shift amount is an unsigned value in the range 1 to number of bits per element. Inactive elements in the destination vector register remain unmodified.</para>
</description>
<status>Green</status>
<predicated>True</predicated>
<takes_movprfx>True</takes_movprfx>
<takes_pred_movprfx>True</takes_pred_movprfx>
</desc>
<alias_list howmany="0"></alias_list>
<classes>
<iclass name="SVE2" oneof="1" id="iclass_sve2" no_encodings="1" isa="A64">
<docvars>
<docvar key="instr-class" value="sve2" />
<docvar key="isa" value="A64" />
<docvar key="mnemonic" value="URSHR" />
</docvars>
<iclassintro count="1"></iclassintro>
<regdiagram form="32" psname="URSHR-Z.P.ZI-_" tworows="1">
<box hibit="31" width="8" settings="8">
<c>0</c>
<c>0</c>
<c>0</c>
<c>0</c>
<c>0</c>
<c>1</c>
<c>0</c>
<c>0</c>
</box>
<box hibit="23" width="2" name="tszh" usename="1">
<c colspan="2"></c>
</box>
<box hibit="21" width="2" settings="2">
<c>0</c>
<c>0</c>
</box>
<box hibit="19" name="opc&lt;1&gt;" settings="1">
<c>1</c>
</box>
<box hibit="18" name="opc&lt;0&gt;" settings="1">
<c>1</c>
</box>
<box hibit="17" name="L" usename="1" settings="1">
<c>0</c>
</box>
<box hibit="16" name="U" usename="1" settings="1">
<c>1</c>
</box>
<box hibit="15" width="3" settings="3">
<c>1</c>
<c>0</c>
<c>0</c>
</box>
<box hibit="12" width="3" name="Pg" usename="1">
<c colspan="3"></c>
</box>
<box hibit="9" width="2" name="tszl" usename="1">
<c colspan="2"></c>
</box>
<box hibit="7" width="3" name="imm3" usename="1">
<c colspan="3"></c>
</box>
<box hibit="4" width="5" name="Zdn" usename="1">
<c colspan="5"></c>
</box>
</regdiagram>
<encoding name="urshr_z_p_zi_" oneofinclass="1" oneof="1" label="">
<docvars>
<docvar key="instr-class" value="sve2" />
<docvar key="isa" value="A64" />
<docvar key="mnemonic" value="URSHR" />
</docvars>
<asmtemplate><text>URSHR </text><a link="sa_zdn" hover="Source and destination scalable vector register (field &quot;Zdn&quot;)">&lt;Zdn&gt;</a><text>.</text><a link="sa_t" hover="Size specifier (field &quot;tszh:tszl&quot;) [B,D,H,S]">&lt;T&gt;</a><text>, </text><a link="sa_pg" hover="Governing scalable predicate register P0-P7 (field &quot;Pg&quot;)">&lt;Pg&gt;</a><text>/M, </text><a link="sa_zdn" hover="Source and destination scalable vector register (field &quot;Zdn&quot;)">&lt;Zdn&gt;</a><text>.</text><a link="sa_t" hover="Size specifier (field &quot;tszh:tszl&quot;) [B,D,H,S]">&lt;T&gt;</a><text>, #</text><a link="sa_const" hover="Immediate shift amount [1-number of bits per element] (field &quot;tszh:tszl:imm3&quot;)">&lt;const&gt;</a></asmtemplate>
</encoding>
<ps_section howmany="1">
<ps name="URSHR-Z.P.ZI-_" mylink="URSHR-Z.P.ZI-_" enclabels="" sections="1" secttype="noheading">
<pstext mayhavelinks="1" section="Decode" rep_section="decode">if !<a link="impl-aarch64.HaveSVE2.0" file="shared_pseudocode.xml" hover="function: boolean HaveSVE2()">HaveSVE2</a>() &amp;&amp; !<a link="impl-aarch64.HaveSME.0" file="shared_pseudocode.xml" hover="function: boolean HaveSME()">HaveSME</a>() then UNDEFINED;
bits(4) tsize = tszh:tszl;
integer esize;
case tsize of
when '0000' UNDEFINED;
when '0001' esize = 8;
when '001x' esize = 16;
when '01xx' esize = 32;
when '1xxx' esize = 64;
integer g = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Pg);
integer dn = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Zdn);
integer shift = (2 * esize) - <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(tsize:imm3);</pstext>
</ps>
</ps_section>
</iclass>
</classes>
<explanations scope="all">
<explanation enclist="urshr_z_p_zi_" symboldefcount="1">
<symbol link="sa_zdn">&lt;Zdn&gt;</symbol>
<account encodedin="Zdn">
<intro>
<para>Is the name of the source and destination scalable vector register, encoded in the "Zdn" field.</para>
</intro>
</account>
</explanation>
<explanation enclist="urshr_z_p_zi_" symboldefcount="1">
<symbol link="sa_t">&lt;T&gt;</symbol>
<definition encodedin="tszh:tszl">
<intro>Is the size specifier, </intro>
<table class="valuetable">
<tgroup cols="3">
<thead>
<row>
<entry class="bitfield">tszh</entry>
<entry class="bitfield">tszl</entry>
<entry class="symbol">&lt;T&gt;</entry>
</row>
</thead>
<tbody>
<row>
<entry class="bitfield">00</entry>
<entry class="bitfield">00</entry>
<entry class="symbol">RESERVED</entry>
</row>
<row>
<entry class="bitfield">00</entry>
<entry class="bitfield">01</entry>
<entry class="symbol">B</entry>
</row>
<row>
<entry class="bitfield">00</entry>
<entry class="bitfield">1x</entry>
<entry class="symbol">H</entry>
</row>
<row>
<entry class="bitfield">01</entry>
<entry class="bitfield">xx</entry>
<entry class="symbol">S</entry>
</row>
<row>
<entry class="bitfield">1x</entry>
<entry class="bitfield">xx</entry>
<entry class="symbol">D</entry>
</row>
</tbody>
</tgroup>
</table>
</definition>
</explanation>
<explanation enclist="urshr_z_p_zi_" symboldefcount="1">
<symbol link="sa_pg">&lt;Pg&gt;</symbol>
<account encodedin="Pg">
<intro>
<para>Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.</para>
</intro>
</account>
</explanation>
<explanation enclist="urshr_z_p_zi_" symboldefcount="1">
<symbol link="sa_const">&lt;const&gt;</symbol>
<account encodedin="imm3:tszh:tszl">
<intro>
<para>Is the immediate shift amount, in the range 1 to number of bits per element, encoded in "tszh:tszl:imm3".</para>
</intro>
</account>
</explanation>
</explanations>
<ps_section howmany="1">
<ps name="URSHR-Z.P.ZI-_" mylink="execute" enclabels="" sections="1" secttype="Operation">
<pstext mayhavelinks="1" section="Execute" rep_section="execute"><a link="impl-aarch64.CheckSVEEnabled.0" file="shared_pseudocode.xml" hover="function: CheckSVEEnabled()">CheckSVEEnabled</a>();
constant integer VL = <a link="impl-aarch64.CurrentVL.read.none" file="shared_pseudocode.xml" hover="accessor: integer CurrentVL">CurrentVL</a>;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
bits(VL) operand1 = <a link="impl-aarch64.Z.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) Z[integer n, integer width]">Z</a>[dn, VL];
bits(PL) mask = <a link="impl-aarch64.P.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) P[integer n, integer width]">P</a>[g, PL];
bits(VL) result;
integer round_const = 1 &lt;&lt; (shift-1);
for e = 0 to elements-1
integer element1 = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(<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>[operand1, e, esize]);
if <a link="impl-aarch64.ActivePredicateElement.3" file="shared_pseudocode.xml" hover="function: boolean ActivePredicateElement(bits(N) pred, integer e, integer esize)">ActivePredicateElement</a>(mask, e, esize) then
integer res = (element1 + round_const) &gt;&gt; shift;
<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, e, esize] = res&lt;esize-1:0&gt;;
else
<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, e, 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>[operand1, e, esize];
<a link="impl-aarch64.Z.write.2" file="shared_pseudocode.xml" hover="accessor: Z[integer n, integer width] = bits(width) value">Z</a>[dn, VL] = result;</pstext>
</ps>
</ps_section>
</instructionsection>