279 lines
11 KiB
XML
279 lines
11 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<?xml-stylesheet type="text/xsl" encoding="UTF-8" href="iform.xsl" version="1.0"?>
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<!DOCTYPE instructionsection PUBLIC "-//ARM//DTD instructionsection //EN" "iform-p.dtd">
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<!-- Copyright (c) 2010-2022 Arm Limited or its affiliates. All rights reserved. -->
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<!-- 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. -->
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<instructionsection id="NOP" title="NOP -- AArch32" type="instruction">
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<docvars>
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<docvar key="instr-class" value="general" />
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<docvar key="mnemonic" value="NOP" />
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</docvars>
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<heading>NOP</heading>
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<desc>
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<brief>
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<para>No Operation</para>
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</brief>
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<authored>
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<para>No Operation does nothing. This instruction can be used for instruction alignment purposes.</para>
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<note>
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<para>The timing effects of including a <instruction>NOP</instruction> instruction in a program are not guaranteed. It can increase execution time, leave it unchanged, or even reduce it. Therefore, <instruction>NOP</instruction> instructions are not suitable for timing loops.</para>
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</note>
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</authored>
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<encodingnotes>
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<para>For more information about the <arm-defined-word>constrained unpredictable</arm-defined-word> behavior of this instruction, see <xref linkend="CJAEGDJC">Architectural Constraints on UNPREDICTABLE behaviors</xref>.</para>
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</encodingnotes>
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</desc>
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<operationalnotes>
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<para>If CPSR.DIT is 1 and this instruction passes its condition execution check:</para>
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<list type="unordered">
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<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>
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<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>
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</list>
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</operationalnotes>
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<alias_list howmany="0"></alias_list>
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<classes>
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<classesintro count="3">
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<txt>It has encodings from the following instruction sets:</txt>
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<txt> A32 (</txt>
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<a href="#iclass_a1">A1</a>
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<txt>)</txt>
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<txt> and </txt>
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<txt> T32 (</txt>
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<a href="#iclass_t1">T1</a>
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<txt> and </txt>
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<a href="#iclass_t2">T2</a>
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<txt>)</txt>
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<txt>.</txt>
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</classesintro>
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<iclass name="A1" oneof="3" id="iclass_a1" no_encodings="1" isa="A32">
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<docvars>
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<docvar key="armarmheading" value="A1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="A32" />
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<docvar key="mnemonic" value="NOP" />
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</docvars>
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<iclassintro count="1"></iclassintro>
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<regdiagram form="32" psname="aarch32/instrs/NOP/A1_A.txt" tworows="1">
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<box hibit="31" width="4" name="cond" usename="1" settings="4" constraint="!= 1111">
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<c colspan="4">!= 1111</c>
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</box>
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<box hibit="27" width="5" settings="5">
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<c>0</c>
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<c>0</c>
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<c>1</c>
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<c>1</c>
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<c>0</c>
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</box>
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<box hibit="22" name="R" settings="1">
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<c>0</c>
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</box>
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<box hibit="21" width="2" settings="2">
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<c>1</c>
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<c>0</c>
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</box>
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<box hibit="19" width="2" name="imm4<3:2>" settings="2">
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<c>0</c>
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<c>0</c>
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</box>
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<box hibit="17" width="2" name="imm4<1:0>" settings="2">
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<c>0</c>
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<c>0</c>
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</box>
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<box hibit="15" settings="1">
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<c>(1)</c>
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</box>
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<box hibit="14" settings="1">
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<c>(1)</c>
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</box>
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<box hibit="13" settings="1">
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<c>(1)</c>
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</box>
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<box hibit="12" settings="1">
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<c>(1)</c>
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</box>
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<box hibit="11" width="12" name="imm12" settings="12">
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<c>(0)</c>
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<c>(0)</c>
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<c>(0)</c>
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<c>(0)</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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</box>
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</regdiagram>
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<encoding name="NOP_A1" oneofinclass="1" oneof="3" label="A1">
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<docvars>
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<docvar key="armarmheading" value="A1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="A32" />
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<docvar key="mnemonic" value="NOP" />
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</docvars>
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<asmtemplate><text>NOP</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><q></a><text>}</text></asmtemplate>
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</encoding>
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<ps_section howmany="1">
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<ps name="aarch32/instrs/NOP/A1_A.txt" mylink="aarch32.instrs.NOP.A1_A.txt" enclabels="" sections="1" secttype="noheading">
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<pstext mayhavelinks="1" section="Decode" rep_section="decode">// No additional decoding required</pstext>
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</ps>
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</ps_section>
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</iclass>
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<iclass name="T1" oneof="3" id="iclass_t1" no_encodings="1" isa="T32">
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<docvars>
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<docvar key="armarmheading" value="T1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="T32" />
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<docvar key="mnemonic" value="NOP" />
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</docvars>
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<iclassintro count="1"></iclassintro>
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<regdiagram form="16" psname="aarch32/instrs/NOP/T1_A.txt">
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<box hibit="31" width="8" settings="8">
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<c>1</c>
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<c>0</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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</box>
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<box hibit="23" width="4" name="hint" settings="4">
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<c>0</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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</box>
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<box hibit="19" width="4" settings="4">
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<c>0</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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</box>
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</regdiagram>
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<encoding name="NOP_T1" oneofinclass="1" oneof="3" label="T1">
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<docvars>
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<docvar key="armarmheading" value="T1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="T32" />
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<docvar key="mnemonic" value="NOP" />
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</docvars>
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<asmtemplate><text>NOP</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><q></a><text>}</text></asmtemplate>
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</encoding>
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<ps_section howmany="1">
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<ps name="aarch32/instrs/NOP/T1_A.txt" mylink="aarch32.instrs.NOP.T1_A.txt" enclabels="" sections="1" secttype="noheading">
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<pstext mayhavelinks="1" section="Decode" rep_section="decode">// No additional decoding required</pstext>
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</ps>
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</ps_section>
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</iclass>
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<iclass name="T2" oneof="3" id="iclass_t2" no_encodings="1" isa="T32">
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<docvars>
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<docvar key="armarmheading" value="T2" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="T32" />
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<docvar key="mnemonic" value="NOP" />
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</docvars>
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<iclassintro count="1"></iclassintro>
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<regdiagram form="16x2" psname="aarch32/instrs/NOP/T2_A.txt">
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<box hibit="31" width="12" settings="12">
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>0</c>
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<c>0</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>0</c>
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<c>1</c>
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<c>0</c>
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</box>
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<box hibit="19" settings="1">
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<c>(1)</c>
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</box>
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<box hibit="18" settings="1">
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<c>(1)</c>
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</box>
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<box hibit="17" settings="1">
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<c>(1)</c>
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</box>
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<box hibit="16" settings="1">
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<c>(1)</c>
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</box>
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<box hibit="15" width="2" settings="2">
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<c>1</c>
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<c>0</c>
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</box>
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<box hibit="13" settings="1">
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<c>(0)</c>
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</box>
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<box hibit="12" settings="1">
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<c>0</c>
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</box>
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<box hibit="11" settings="1">
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<c>(0)</c>
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</box>
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<box hibit="10" width="3" settings="3">
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<c>0</c>
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<c>0</c>
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<c>0</c>
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</box>
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<box hibit="7" width="4" name="hint" settings="4">
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<c>0</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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</box>
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<box hibit="3" width="4" name="option" settings="4">
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<c>0</c>
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<c>0</c>
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<c>0</c>
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<c>0</c>
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</box>
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</regdiagram>
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<encoding name="NOP_T2" oneofinclass="1" oneof="3" label="T2">
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<docvars>
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<docvar key="armarmheading" value="T2" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="T32" />
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<docvar key="mnemonic" value="NOP" />
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</docvars>
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<asmtemplate><text>NOP</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>.W</text></asmtemplate>
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</encoding>
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<ps_section howmany="1">
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<ps name="aarch32/instrs/NOP/T2_A.txt" mylink="aarch32.instrs.NOP.T2_A.txt" enclabels="" sections="1" secttype="noheading">
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<pstext mayhavelinks="1" section="Decode" rep_section="decode">// No additional decoding required</pstext>
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</ps>
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</ps_section>
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</iclass>
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</classes>
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<explanations scope="all">
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<explanation enclist="NOP_A1, NOP_T1, NOP_T2" symboldefcount="1">
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<symbol link="sa_c"><c></symbol>
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<account encodedin="">
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<intro>
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<para>See <xref linkend="Babbefhf">Standard assembler syntax fields</xref>.</para>
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</intro>
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</account>
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</explanation>
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<explanation enclist="NOP_A1, NOP_T1" symboldefcount="1">
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<symbol link="sa_q"><q></symbol>
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<account encodedin="">
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<intro>
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<para>See <xref linkend="Babbefhf">Standard assembler syntax fields</xref>.</para>
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</intro>
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</account>
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</explanation>
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</explanations>
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<ps_section howmany="1">
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<ps name="aarch32/instrs/NOP/Op_A.txt" mylink="execute" enclabels="" sections="1" secttype="Operation">
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<pstext mayhavelinks="1" section="Execute" rep_section="execute">if <a link="impl-aarch32.ConditionPassed.0" file="shared_pseudocode.xml" hover="function: boolean ConditionPassed()">ConditionPassed</a>() then
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EncodingSpecificOperations();
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// Do nothing</pstext>
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</ps>
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</ps_section>
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</instructionsection>
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