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<instructionsection id="FMUL_float" title="FMUL (scalar) -- A64" type="instruction">
  <docvars>
    <docvar key="instr-class" value="float"/>
    <docvar key="isa" value="A64"/>
    <docvar key="mnemonic" value="FMUL"/>
  </docvars>
  <heading>FMUL (scalar)</heading>
  <desc>
    <brief>
      <para>Floating-point multiply (scalar)</para>
    </brief>
    <authored>
      <para>This instruction multiplies the floating-point values of the two source SIMD&amp;FP
registers, and writes the result to the destination SIMD&amp;FP register.</para>
      <para>This instruction can generate a floating-point exception.
  Depending on the settings in <register_link id="AArch64-fpcr.xml" state="AArch64">FPCR</register_link>,
  the exception results in either a flag being set in <register_link id="AArch64-fpsr.xml" state="AArch64">FPSR</register_link>
  or a synchronous exception being generated.
  For more information, see
  <xref linkend="ARMARM_BEIJDDAG">Floating-point exceptions and exception traps</xref>.</para>
      <para>Depending on the settings in the <register_link id="AArch64-cpacr_el1.xml" state="AArch64">CPACR_EL1</register_link>,
  <register_link id="AArch64-cptr_el2.xml" state="AArch64">CPTR_EL2</register_link>, and <register_link id="AArch64-cptr_el3.xml" state="AArch64">CPTR_EL3</register_link> registers,
  and the current Security state and Exception level,
  an attempt to execute the instruction might be trapped.</para>
    </authored>
  </desc>
  <alias_list howmany="0"/>
  <classes>
    <iclass name="Floating-point" oneof="1" id="iclass_floating_point" no_encodings="3" isa="A64">
      <docvars>
        <docvar key="instr-class" value="float"/>
        <docvar key="isa" value="A64"/>
        <docvar key="mnemonic" value="FMUL"/>
      </docvars>
      <iclassintro count="3"/>
      <regdiagram form="32" psname="A64.simd_dp.floatdp2.FMUL_H_floatdp2" tworows="1">
        <box hibit="31" name="M" usename="1" settings="1" psbits="x">
          <c>0</c>
        </box>
        <box hibit="30" width="1" settings="1">
          <c>0</c>
        </box>
        <box hibit="29" name="S" usename="1" settings="1" psbits="x">
          <c>0</c>
        </box>
        <box hibit="28" width="5" settings="5">
          <c>1</c>
          <c>1</c>
          <c>1</c>
          <c>1</c>
          <c>0</c>
        </box>
        <box hibit="23" width="2" name="ftype" usename="1">
          <c colspan="2"/>
        </box>
        <box hibit="21" width="1" settings="1">
          <c>1</c>
        </box>
        <box hibit="20" width="5" name="Rm" usename="1">
          <c colspan="5"/>
        </box>
        <box hibit="15" name="op" usename="1" settings="1" psbits="x">
          <c>0</c>
        </box>
        <box hibit="14" width="5" settings="5">
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>1</c>
          <c>0</c>
        </box>
        <box hibit="9" width="5" name="Rn" usename="1">
          <c colspan="5"/>
        </box>
        <box hibit="4" width="5" name="Rd" usename="1">
          <c colspan="5"/>
        </box>
      </regdiagram>
      <encoding name="FMUL_H_floatdp2" oneofinclass="3" oneof="3" label="Half-precision" bitdiffs="ftype == 11">
        <docvars>
          <docvar key="datatype" value="half"/>
          <docvar key="instr-class" value="float"/>
          <docvar key="isa" value="A64"/>
          <docvar key="mnemonic" value="FMUL"/>
        </docvars>
        <arch_variants>
          <arch_variant feature="FEAT_FP16" name="v8Ap2"/>
        </arch_variants>
        <box hibit="23" width="2" name="ftype">
          <c>1</c>
          <c>1</c>
        </box>
        <asmtemplate><text>FMUL  </text><a hover="Is the 16-bit name of the SIMD&amp;FP destination register, encoded in the &quot;Rd&quot; field." link="Hd">&lt;Hd&gt;</a><text>, </text><a hover="For the &quot;Half-precision&quot; variant: is the 16-bit name of the first SIMD&amp;FP source register, encoded in the &quot;Rn&quot; field." link="Hn">&lt;Hn&gt;</a><text>, </text><a hover="Is the 16-bit name of the second SIMD&amp;FP source register, encoded in the &quot;Rm&quot; field." link="Hm">&lt;Hm&gt;</a></asmtemplate>
      </encoding>
      <encoding name="FMUL_S_floatdp2" oneofinclass="3" oneof="3" label="Single-precision" bitdiffs="ftype == 00">
        <docvars>
          <docvar key="datatype" value="single"/>
          <docvar key="instr-class" value="float"/>
          <docvar key="isa" value="A64"/>
          <docvar key="mnemonic" value="FMUL"/>
        </docvars>
        <arch_variants>
          <arch_variant feature="FEAT_FP" name="v8Ap0"/>
        </arch_variants>
        <box hibit="23" width="2" name="ftype">
          <c>0</c>
          <c>0</c>
        </box>
        <asmtemplate><text>FMUL  </text><a hover="Is the 32-bit name of the SIMD&amp;FP destination register, encoded in the &quot;Rd&quot; field." link="Sd">&lt;Sd&gt;</a><text>, </text><a hover="For the &quot;Single-precision&quot; variant: is the 32-bit name of the first SIMD&amp;FP source register, encoded in the &quot;Rn&quot; field." link="Sn__3">&lt;Sn&gt;</a><text>, </text><a hover="Is the 32-bit name of the second SIMD&amp;FP source register, encoded in the &quot;Rm&quot; field." link="Sm">&lt;Sm&gt;</a></asmtemplate>
      </encoding>
      <encoding name="FMUL_D_floatdp2" oneofinclass="3" oneof="3" label="Double-precision" bitdiffs="ftype == 01">
        <docvars>
          <docvar key="datatype" value="double"/>
          <docvar key="instr-class" value="float"/>
          <docvar key="isa" value="A64"/>
          <docvar key="mnemonic" value="FMUL"/>
        </docvars>
        <arch_variants>
          <arch_variant feature="FEAT_FP" name="v8Ap0"/>
        </arch_variants>
        <box hibit="23" width="2" name="ftype">
          <c>0</c>
          <c>1</c>
        </box>
        <asmtemplate><text>FMUL  </text><a hover="Is the 64-bit name of the SIMD&amp;FP destination register, encoded in the &quot;Rd&quot; field." link="Dd">&lt;Dd&gt;</a><text>, </text><a hover="For the &quot;Double-precision&quot; variant: is the 64-bit name of the first SIMD&amp;FP source register, encoded in the &quot;Rn&quot; field." link="Dn__2">&lt;Dn&gt;</a><text>, </text><a hover="Is the 64-bit name of the second SIMD&amp;FP source register, encoded in the &quot;Rm&quot; field." link="Dm">&lt;Dm&gt;</a></asmtemplate>
      </encoding>
      <ps_section howmany="1">
        <ps name="A64.simd_dp.floatdp2.FMUL_H_floatdp2" sections="1" secttype="noheading">
          <pstext mayhavelinks="1" section="Decode" rep_section="decode">if !IsFeatureImplemented(FEAT_FP) then EndOfDecode(Decode_UNDEF); end;
if ftype == '10' then EndOfDecode(Decode_UNDEF); end;
if ftype == '11' &amp;&amp; !IsFeatureImplemented(FEAT_FP16) then EndOfDecode(Decode_UNDEF); end;

let d : integer{} = UInt(Rd);
let n : integer{} = UInt(Rn);
let m : integer{} = UInt(Rm);

let esize : integer{} = 8 &lt;&lt; UInt(ftype XOR '10');</pstext></ps>
      </ps_section>
    </iclass>
  </classes>
  <explanations scope="all">
    <explanation enclist="FMUL_H_floatdp2" symboldefcount="1">
      <symbol link="Hd">&lt;Hd&gt;</symbol>
      <account encodedin="Rd">
        <intro>
          <para>Is the 16-bit name of the SIMD&amp;FP destination register, encoded in the "Rd" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="FMUL_H_floatdp2" symboldefcount="1">
      <symbol link="Hn">&lt;Hn&gt;</symbol>
      <account encodedin="Rn">
        <intro>
          <para>Is the 16-bit name of the first SIMD&amp;FP source register, encoded in the "Rn" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="FMUL_H_floatdp2" symboldefcount="1">
      <symbol link="Hm">&lt;Hm&gt;</symbol>
      <account encodedin="Rm">
        <intro>
          <para>Is the 16-bit name of the second SIMD&amp;FP source register, encoded in the "Rm" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="FMUL_S_floatdp2" symboldefcount="1">
      <symbol link="Sd">&lt;Sd&gt;</symbol>
      <account encodedin="Rd">
        <intro>
          <para>Is the 32-bit name of the SIMD&amp;FP destination register, encoded in the "Rd" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="FMUL_S_floatdp2" symboldefcount="1">
      <symbol link="Sn__3">&lt;Sn&gt;</symbol>
      <account encodedin="Rn">
        <intro>
          <para>Is the 32-bit name of the first SIMD&amp;FP source register, encoded in the "Rn" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="FMUL_S_floatdp2" symboldefcount="1">
      <symbol link="Sm">&lt;Sm&gt;</symbol>
      <account encodedin="Rm">
        <intro>
          <para>Is the 32-bit name of the second SIMD&amp;FP source register, encoded in the "Rm" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="FMUL_D_floatdp2" symboldefcount="1">
      <symbol link="Dd">&lt;Dd&gt;</symbol>
      <account encodedin="Rd">
        <intro>
          <para>Is the 64-bit name of the SIMD&amp;FP destination register, encoded in the "Rd" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="FMUL_D_floatdp2" symboldefcount="1">
      <symbol link="Dn__2">&lt;Dn&gt;</symbol>
      <account encodedin="Rn">
        <intro>
          <para>Is the 64-bit name of the first SIMD&amp;FP source register, encoded in the "Rn" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="FMUL_D_floatdp2" symboldefcount="1">
      <symbol link="Dm">&lt;Dm&gt;</symbol>
      <account encodedin="Rm">
        <intro>
          <para>Is the 64-bit name of the second SIMD&amp;FP source register, encoded in the "Rm" field.</para>
        </intro>
      </account>
    </explanation>
  </explanations>
  <ps_section howmany="1">
    <ps name="A64.simd_dp.floatdp2.FMUL_H_floatdp2" sections="1" secttype="Operation">
      <pstext mayhavelinks="1" section="Execute" rep_section="execute">AArch64_CheckFPEnabled();
let operand1 : bits(esize) = V{}(n);
let operand2 : bits(esize) = V{}(m);

var result : bits(128) = if IsMerging(FPCR()) then V{128}(n) else Zeros{128};

result[0+:esize]  = FPMul{esize}(operand1, operand2, FPCR());

V{128}(d) = result;</pstext></ps>
  </ps_section>
  <timestamp>2026-03-12 12:23:09</timestamp>
  <commit_id>2025-09_rel_asl1</commit_id>
</instructionsection>
