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<instructionsection id="MUL" title="MUL, MULS -- AArch32" type="instruction">
  <docvars>
    <docvar key="instr-class" value="general" />
  </docvars>
  <heading>MUL, MULS</heading>
  <desc>
    <brief>
      <para>Multiply</para>
    </brief>
    <authored>
      <para>Multiply multiplies two register values. The least significant 32 bits of the result are written to the destination register. These 32 bits do not depend on whether the source register values are considered to be signed values or unsigned values.</para>
      <para>Optionally, it can update the condition flags based on the result. In the T32 instruction set, this option is limited to only a few forms of the instruction. Use of this option adversely affects performance on many implementations.</para>
    </authored>
    <encodingnotes>
      <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>
    </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="3">
      <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> and </txt>
      <a href="#iclass_t2">T2</a>
      <txt>)</txt>
      <txt>.</txt>
    </classesintro>
    <iclass name="A1" oneof="3" id="iclass_a1" no_encodings="2" isa="A32">
      <docvars>
        <docvar key="armarmheading" value="A1" />
        <docvar key="instr-class" value="general" />
        <docvar key="isa" value="A32" />
      </docvars>
      <iclassintro count="2"></iclassintro>
      <regdiagram form="32" psname="aarch32/instrs/MUL/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="4" settings="4">
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="23" width="3" name="opc" settings="3">
          <c>0</c>
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="20" name="S" usename="1">
          <c></c>
        </box>
        <box hibit="19" width="4" name="Rd" usename="1">
          <c colspan="4"></c>
        </box>
        <box hibit="15" width="4" name="RdLo" settings="4">
          <c>(0)</c>
          <c>(0)</c>
          <c>(0)</c>
          <c>(0)</c>
        </box>
        <box hibit="11" width="4" name="Rm" usename="1">
          <c colspan="4"></c>
        </box>
        <box hibit="7" width="4" settings="4">
          <c>1</c>
          <c>0</c>
          <c>0</c>
          <c>1</c>
        </box>
        <box hibit="3" width="4" name="Rn" usename="1">
          <c colspan="4"></c>
        </box>
      </regdiagram>
      <encoding name="MULS_A1" oneofinclass="2" oneof="4" label="Flag setting" bitdiffs="S == 1">
        <docvars>
          <docvar key="armarmheading" value="A1" />
          <docvar key="cond-setting" value="s" />
          <docvar key="instr-class" value="general" />
          <docvar key="isa" value="A32" />
          <docvar key="mnemonic" value="MULS" />
        </docvars>
        <box hibit="20" width="1" name="S">
          <c>1</c>
        </box>
        <asmtemplate><text>MULS</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_rd" hover="General-purpose destination register (field &quot;Rd&quot;)">&lt;Rd&gt;</a><text>, </text><a link="sa_rn" hover="First general-purpose source register holding multiplicand (field &quot;Rn&quot;)">&lt;Rn&gt;</a><text>{</text><text>, </text><a link="sa_rm" hover="Second general-purpose source register holding multiplier (field &quot;Rm&quot;)">&lt;Rm&gt;</a><text>}</text></asmtemplate>
      </encoding>
      <encoding name="MUL_A1" oneofinclass="2" oneof="4" label="Not flag setting" bitdiffs="S == 0">
        <docvars>
          <docvar key="armarmheading" value="A1" />
          <docvar key="cond-setting" value="no-s" />
          <docvar key="instr-class" value="general" />
          <docvar key="isa" value="A32" />
          <docvar key="mnemonic" value="MUL" />
        </docvars>
        <box hibit="20" width="1" name="S">
          <c>0</c>
        </box>
        <asmtemplate><text>MUL</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_rd" hover="General-purpose destination register (field &quot;Rd&quot;)">&lt;Rd&gt;</a><text>, </text><a link="sa_rn" hover="First general-purpose source register holding multiplicand (field &quot;Rn&quot;)">&lt;Rn&gt;</a><text>{</text><text>, </text><a link="sa_rm" hover="Second general-purpose source register holding multiplier (field &quot;Rm&quot;)">&lt;Rm&gt;</a><text>}</text></asmtemplate>
      </encoding>
      <ps_section howmany="1">
        <ps name="aarch32/instrs/MUL/A1_A.txt" mylink="aarch32.instrs.MUL.A1_A.txt" enclabels="" sections="1" secttype="noheading">
          <pstext mayhavelinks="1" section="Decode" rep_section="decode">d = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rd);  n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn);  m = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rm);  setflags = (S == '1');
if d == 15 || n == 15 || m == 15 then UNPREDICTABLE;</pstext>
        </ps>
      </ps_section>
    </iclass>
    <iclass name="T1" oneof="3" 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="MUL" />
      </docvars>
      <iclassintro count="1"></iclassintro>
      <regdiagram form="16" psname="aarch32/instrs/MUL/T1_A.txt">
        <box hibit="31" width="6" settings="6">
          <c>0</c>
          <c>1</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="25" width="4" name="op" settings="4">
          <c>1</c>
          <c>1</c>
          <c>0</c>
          <c>1</c>
        </box>
        <box hibit="21" width="3" name="Rn" usename="1">
          <c colspan="3"></c>
        </box>
        <box hibit="18" width="3" name="Rdm" usename="1">
          <c colspan="3"></c>
        </box>
      </regdiagram>
      <encoding name="MUL_T1" oneofinclass="1" oneof="4" label="T1">
        <docvars>
          <docvar key="armarmheading" value="T1" />
          <docvar key="instr-class" value="general" />
          <docvar key="isa" value="T32" />
          <docvar key="mnemonic" value="MUL" />
        </docvars>
        <asmtemplate comment="Inside IT block"><text>MUL</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}">&lt;c&gt;</a><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_rdm" hover="Second general-purpose source register holding multiplier and the destination register (field &quot;Rdm&quot;)">&lt;Rdm&gt;</a><text>, </text><a link="sa_rn" hover="First general-purpose source register holding multiplicand (field &quot;Rn&quot;)">&lt;Rn&gt;</a><text>{</text><text>, </text><a link="sa_rdm" hover="Second general-purpose source register holding multiplier and the destination register (field &quot;Rdm&quot;)">&lt;Rdm&gt;</a><text>}</text></asmtemplate>
        <asmtemplate comment="Outside IT block"><text>MULS</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_rdm" hover="Second general-purpose source register holding multiplier and the destination register (field &quot;Rdm&quot;)">&lt;Rdm&gt;</a><text>, </text><a link="sa_rn" hover="First general-purpose source register holding multiplicand (field &quot;Rn&quot;)">&lt;Rn&gt;</a><text>{</text><text>, </text><a link="sa_rdm" hover="Second general-purpose source register holding multiplier and the destination register (field &quot;Rdm&quot;)">&lt;Rdm&gt;</a><text>}</text></asmtemplate>
      </encoding>
      <ps_section howmany="1">
        <ps name="aarch32/instrs/MUL/T1_A.txt" mylink="aarch32.instrs.MUL.T1_A.txt" enclabels="" sections="1" secttype="noheading">
          <pstext mayhavelinks="1" section="Decode" rep_section="decode">d = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rdm);  n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn);  m = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rdm);  setflags = !<a link="impl-aarch32.InITBlock.0" file="shared_pseudocode.xml" hover="function: boolean InITBlock()">InITBlock</a>();</pstext>
        </ps>
      </ps_section>
    </iclass>
    <iclass name="T2" oneof="3" id="iclass_t2" no_encodings="1" isa="T32">
      <docvars>
        <docvar key="armarmheading" value="T2" />
        <docvar key="instr-class" value="general" />
        <docvar key="isa" value="T32" />
        <docvar key="mnemonic" value="MUL" />
      </docvars>
      <iclassintro count="1"></iclassintro>
      <regdiagram form="16x2" psname="aarch32/instrs/MUL/T2_A.txt">
        <box hibit="31" width="9" settings="9">
          <c>1</c>
          <c>1</c>
          <c>1</c>
          <c>1</c>
          <c>1</c>
          <c>0</c>
          <c>1</c>
          <c>1</c>
          <c>0</c>
        </box>
        <box hibit="22" width="3" name="op1" settings="3">
          <c>0</c>
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="19" width="4" name="Rn" usename="1">
          <c colspan="4"></c>
        </box>
        <box hibit="15" width="4" name="Ra" settings="4">
          <c>1</c>
          <c>1</c>
          <c>1</c>
          <c>1</c>
        </box>
        <box hibit="11" width="4" name="Rd" usename="1">
          <c colspan="4"></c>
        </box>
        <box hibit="7" width="2" settings="2">
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="5" width="2" name="op2" settings="2">
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="3" width="4" name="Rm" usename="1">
          <c colspan="4"></c>
        </box>
      </regdiagram>
      <encoding name="MUL_T2" oneofinclass="1" oneof="4" label="T2">
        <docvars>
          <docvar key="armarmheading" value="T2" />
          <docvar key="instr-class" value="general" />
          <docvar key="isa" value="T32" />
          <docvar key="mnemonic" value="MUL" />
        </docvars>
        <asmtemplate comment="Inside IT block, and &lt;Rd&gt;, &lt;Rn&gt;, &lt;Rm&gt; can be represented in T1"><text>MUL</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}">&lt;c&gt;</a><text>.W </text><a link="sa_rd" hover="General-purpose destination register (field &quot;Rd&quot;)">&lt;Rd&gt;</a><text>, </text><a link="sa_rn" hover="First general-purpose source register holding multiplicand (field &quot;Rn&quot;)">&lt;Rn&gt;</a><text>{</text><text>, </text><a link="sa_rm" hover="Second general-purpose source register holding multiplier (field &quot;Rm&quot;)">&lt;Rm&gt;</a><text>}</text></asmtemplate>
        <asmtemplate><text>MUL</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_rd" hover="General-purpose destination register (field &quot;Rd&quot;)">&lt;Rd&gt;</a><text>, </text><a link="sa_rn" hover="First general-purpose source register holding multiplicand (field &quot;Rn&quot;)">&lt;Rn&gt;</a><text>{</text><text>, </text><a link="sa_rm" hover="Second general-purpose source register holding multiplier (field &quot;Rm&quot;)">&lt;Rm&gt;</a><text>}</text></asmtemplate>
      </encoding>
      <ps_section howmany="1">
        <ps name="aarch32/instrs/MUL/T2_A.txt" mylink="aarch32.instrs.MUL.T2_A.txt" enclabels="" sections="1" secttype="noheading">
          <pstext mayhavelinks="1" section="Decode" rep_section="decode">d = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rd);  n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn);  m = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rm);  setflags = FALSE;
if d == 15 || n == 15 || m == 15 then UNPREDICTABLE; // Armv8-A removes UNPREDICTABLE for R13</pstext>
        </ps>
      </ps_section>
    </iclass>
  </classes>
  <explanations scope="all">
    <explanation enclist="MUL_A1, MUL_T1, MUL_T2" 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="MUL_A1, MUL_T1, MUL_T2" 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="MUL_T1" symboldefcount="1">
      <symbol link="sa_rdm">&lt;Rdm&gt;</symbol>
      <account encodedin="Rdm">
        <intro>
          <para>Is the second general-purpose source register holding the multiplier and the destination register, encoded in the "Rdm" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="MUL_A1, MUL_T2" symboldefcount="1">
      <symbol link="sa_rd">&lt;Rd&gt;</symbol>
      <account encodedin="Rd">
        <intro>
          <para>Is the general-purpose destination register, encoded in the "Rd" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="MUL_A1, MUL_T1, MUL_T2" symboldefcount="1">
      <symbol link="sa_rn">&lt;Rn&gt;</symbol>
      <account encodedin="Rn">
        <intro>
          <para>Is the first general-purpose source register holding the multiplicand, encoded in the "Rn" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="MUL_A1, MUL_T2" symboldefcount="1">
      <symbol link="sa_rm">&lt;Rm&gt;</symbol>
      <account encodedin="Rm">
        <intro>
          <para>Is the second general-purpose source register holding the multiplier, encoded in the "Rm" field. If omitted, <syntax>&lt;Rd&gt;</syntax> is used.</para>
        </intro>
      </account>
    </explanation>
  </explanations>
  <ps_section howmany="1">
    <ps name="aarch32/instrs/MUL/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();
    operand1 = <a link="impl-shared.SInt.1" file="shared_pseudocode.xml" hover="function: integer SInt(bits(N) x)">SInt</a>(<a link="impl-aarch32.R.read.1" file="shared_pseudocode.xml" hover="accessor: bits(32) R[integer n]">R</a>[n]);  // operand1 = UInt(R[n]) produces the same final results
    operand2 = <a link="impl-shared.SInt.1" file="shared_pseudocode.xml" hover="function: integer SInt(bits(N) x)">SInt</a>(<a link="impl-aarch32.R.read.1" file="shared_pseudocode.xml" hover="accessor: bits(32) R[integer n]">R</a>[m]);  // operand2 = UInt(R[m]) produces the same final results
    result = operand1 * operand2;
    <a link="impl-aarch32.R.write.1" file="shared_pseudocode.xml" hover="accessor: R[integer n] = bits(32) value">R</a>[d] = result&lt;31:0&gt;;
    if setflags then
        PSTATE.N = result&lt;31&gt;;
        PSTATE.Z = <a link="impl-shared.IsZeroBit.1" file="shared_pseudocode.xml" hover="function: bit IsZeroBit(bits(N) x)">IsZeroBit</a>(result&lt;31:0&gt;);
        // PSTATE.C, PSTATE.V unchanged</pstext>
    </ps>
  </ps_section>
</instructionsection>
