slonik/specs/cmn_i.xml

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XML

<?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="CMN_i" title="CMN (immediate) -- AArch32" type="instruction">
<docvars>
<docvar key="instr-class" value="general" />
<docvar key="mnemonic" value="CMN" />
</docvars>
<heading>CMN (immediate)</heading>
<desc>
<brief>
<para>Compare Negative (immediate)</para>
</brief>
<authored>
<para>Compare Negative (immediate) adds a register value and an immediate value. It updates the condition flags based on the result, and discards the result.</para>
</authored>
<encodingnotes>
<para>For more information about the <arm-defined-word>constrained unpredictable</arm-defined-word> behavior, see <xref linkend="CJAEGDJC">Architectural Constraints on UNPREDICTABLE behaviors</xref>.</para>
</encodingnotes>
</desc>
<operationalnotes>
<para>If CPSR.DIT is 1, this instruction has passed its condition execution check, and does not use R15 as either its source or destination:</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>
<classesintro count="2">
<txt>It has encodings from the following instruction sets:</txt>
<txt> A32 (</txt>
<a href="#iclass_a1">A1</a>
<txt>)</txt>
<txt> and </txt>
<txt> T32 (</txt>
<a href="#iclass_t1">T1</a>
<txt>)</txt>
<txt>.</txt>
</classesintro>
<iclass name="A1" oneof="2" id="iclass_a1" no_encodings="1" isa="A32">
<docvars>
<docvar key="armarmheading" value="A1" />
<docvar key="instr-class" value="general" />
<docvar key="isa" value="A32" />
<docvar key="mnemonic" value="CMN" />
</docvars>
<iclassintro count="1"></iclassintro>
<regdiagram form="32" psname="aarch32/instrs/CMN_i/A1_A.txt" tworows="1">
<box hibit="31" width="4" name="cond" usename="1" settings="4" constraint="!= 1111">
<c colspan="4">!= 1111</c>
</box>
<box hibit="27" width="5" settings="5">
<c>0</c>
<c>0</c>
<c>1</c>
<c>1</c>
<c>0</c>
</box>
<box hibit="22" width="2" name="opc" settings="2">
<c>1</c>
<c>1</c>
</box>
<box hibit="20" settings="1">
<c>1</c>
</box>
<box hibit="19" width="4" name="Rn" usename="1">
<c colspan="4"></c>
</box>
<box hibit="15" settings="1">
<c>(0)</c>
</box>
<box hibit="14" settings="1">
<c>(0)</c>
</box>
<box hibit="13" settings="1">
<c>(0)</c>
</box>
<box hibit="12" settings="1">
<c>(0)</c>
</box>
<box hibit="11" width="12" name="imm12" usename="1">
<c colspan="12"></c>
</box>
</regdiagram>
<encoding name="CMN_i_A1" oneofinclass="1" oneof="2" label="A1">
<docvars>
<docvar key="armarmheading" value="A1" />
<docvar key="instr-class" value="general" />
<docvar key="isa" value="A32" />
<docvar key="mnemonic" value="CMN" />
</docvars>
<asmtemplate><text>CMN</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}">&lt;c&gt;</a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}">&lt;q&gt;</a><text>}</text><text> </text><a link="sa_rn_1" hover="General-purpose source register (field &quot;Rn&quot;)">&lt;Rn&gt;</a><text>, #</text><a link="sa_const_1" hover="An immediate value">&lt;const&gt;</a></asmtemplate>
</encoding>
<ps_section howmany="1">
<ps name="aarch32/instrs/CMN_i/A1_A.txt" mylink="aarch32.instrs.CMN_i.A1_A.txt" enclabels="" sections="1" secttype="noheading">
<pstext mayhavelinks="1" section="Decode" rep_section="decode">n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn); imm32 = <a link="impl-aarch32.A32ExpandImm.1" file="shared_pseudocode.xml" hover="function: bits(32) A32ExpandImm(bits(12) imm12)">A32ExpandImm</a>(imm12);</pstext>
</ps>
</ps_section>
</iclass>
<iclass name="T1" oneof="2" id="iclass_t1" no_encodings="1" isa="T32">
<docvars>
<docvar key="armarmheading" value="T1" />
<docvar key="instr-class" value="general" />
<docvar key="isa" value="T32" />
<docvar key="mnemonic" value="CMN" />
</docvars>
<iclassintro count="1"></iclassintro>
<regdiagram form="16x2" psname="aarch32/instrs/CMN_i/T1_A.txt">
<box hibit="31" width="5" settings="5">
<c>1</c>
<c>1</c>
<c>1</c>
<c>1</c>
<c>0</c>
</box>
<box hibit="26" name="i" usename="1">
<c></c>
</box>
<box hibit="25" settings="1">
<c>0</c>
</box>
<box hibit="24" width="4" name="op1" settings="4">
<c>1</c>
<c>0</c>
<c>0</c>
<c>0</c>
</box>
<box hibit="20" name="S" settings="1">
<c>1</c>
</box>
<box hibit="19" width="4" name="Rn" usename="1">
<c colspan="4"></c>
</box>
<box hibit="15" settings="1">
<c>0</c>
</box>
<box hibit="14" width="3" name="imm3" usename="1">
<c colspan="3"></c>
</box>
<box hibit="11" width="4" name="Rd" settings="4">
<c>1</c>
<c>1</c>
<c>1</c>
<c>1</c>
</box>
<box hibit="7" width="8" name="imm8" usename="1">
<c colspan="8"></c>
</box>
</regdiagram>
<encoding name="CMN_i_T1" oneofinclass="1" oneof="2" label="T1">
<docvars>
<docvar key="armarmheading" value="T1" />
<docvar key="instr-class" value="general" />
<docvar key="isa" value="T32" />
<docvar key="mnemonic" value="CMN" />
</docvars>
<asmtemplate><text>CMN</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}">&lt;c&gt;</a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}">&lt;q&gt;</a><text>}</text><text> </text><a link="sa_rn" hover="General-purpose source register (field &quot;Rn&quot;)">&lt;Rn&gt;</a><text>, #</text><a link="sa_const" hover="An immediate value">&lt;const&gt;</a></asmtemplate>
</encoding>
<ps_section howmany="1">
<ps name="aarch32/instrs/CMN_i/T1_A.txt" mylink="aarch32.instrs.CMN_i.T1_A.txt" enclabels="" sections="1" secttype="noheading">
<pstext mayhavelinks="1" section="Decode" rep_section="decode">n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn); imm32 = <a link="impl-aarch32.T32ExpandImm.1" file="shared_pseudocode.xml" hover="function: bits(32) T32ExpandImm(bits(12) imm12)">T32ExpandImm</a>(i:imm3:imm8);
if n == 15 then UNPREDICTABLE;</pstext>
</ps>
</ps_section>
</iclass>
</classes>
<explanations scope="all">
<explanation enclist="CMN_i_A1, CMN_i_T1" symboldefcount="1">
<symbol link="sa_c">&lt;c&gt;</symbol>
<account encodedin="">
<intro>
<para>See <xref linkend="Babbefhf">Standard assembler syntax fields</xref>.</para>
</intro>
</account>
</explanation>
<explanation enclist="CMN_i_A1, CMN_i_T1" symboldefcount="1">
<symbol link="sa_q">&lt;q&gt;</symbol>
<account encodedin="">
<intro>
<para>See <xref linkend="Babbefhf">Standard assembler syntax fields</xref>.</para>
</intro>
</account>
</explanation>
<explanation enclist="CMN_i_A1" symboldefcount="1">
<symbol link="sa_rn_1">&lt;Rn&gt;</symbol>
<account encodedin="Rn">
<docvars>
<docvar key="armarmheading" value="A1" />
<docvar key="isa" value="A32" />
</docvars>
<intro>
<para>For encoding A1: is the general-purpose source register, encoded in the "Rn" field. The PC can be used, but this is deprecated.</para>
</intro>
</account>
</explanation>
<explanation enclist="CMN_i_T1" symboldefcount="2">
<symbol link="sa_rn">&lt;Rn&gt;</symbol>
<account encodedin="Rn">
<docvars>
<docvar key="armarmheading" value="T1" />
<docvar key="isa" value="T32" />
</docvars>
<intro>
<para>For encoding T1: is the general-purpose source register, encoded in the "Rn" field.</para>
</intro>
</account>
</explanation>
<explanation enclist="CMN_i_A1" symboldefcount="1">
<symbol link="sa_const_1">&lt;const&gt;</symbol>
<account encodedin="imm12">
<docvars>
<docvar key="armarmheading" value="A1" />
<docvar key="isa" value="A32" />
</docvars>
<intro>
<para>For encoding A1: an immediate value. See <xref linkend="BABHDAJF">Modified immediate constants in A32 instructions</xref> for the range of values.</para>
</intro>
</account>
</explanation>
<explanation enclist="CMN_i_T1" symboldefcount="2">
<symbol link="sa_const">&lt;const&gt;</symbol>
<account encodedin="i:imm3:imm8">
<docvars>
<docvar key="armarmheading" value="T1" />
<docvar key="isa" value="T32" />
</docvars>
<intro>
<para>For encoding T1: an immediate value. See <xref linkend="BABGHAGA">Modified immediate constants in T32 instructions</xref> for the range of values.</para>
</intro>
</account>
</explanation>
</explanations>
<ps_section howmany="1">
<ps name="aarch32/instrs/CMN_i/Op_A.txt" mylink="execute" enclabels="" sections="1" secttype="Operation">
<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
EncodingSpecificOperations();
(result, nzcv) = <a link="impl-shared.AddWithCarry.3" file="shared_pseudocode.xml" hover="function: (bits(N), bits(4)) AddWithCarry(bits(N) x, bits(N) y, bit carry_in)">AddWithCarry</a>(<a link="impl-aarch32.R.read.1" file="shared_pseudocode.xml" hover="accessor: bits(32) R[integer n]">R</a>[n], imm32, '0');
PSTATE.&lt;N,Z,C,V&gt; = nzcv;</pstext>
</ps>
</ps_section>
</instructionsection>