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<instructionsection id="CLS_int" title="CLS -- A64" type="instruction">
  <docvars>
    <docvar key="instr-class" value="general" />
    <docvar key="isa" value="A64" />
    <docvar key="mnemonic" value="CLS" />
  </docvars>
  <heading>CLS</heading>
  <desc>
    <brief>
      <para>Count Leading Sign bits</para>
    </brief>
    <authored>
      <para>Count Leading Sign bits counts the number of leading bits of the source register that have the same value as the most significant bit of the register, and writes the result to the destination register. This count does not include the most significant bit of the source register.</para>
    </authored>
  </desc>
  <operationalnotes>
    <para>If PSTATE.DIT is 1:</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>
    <iclass name="Integer" oneof="1" id="iclass_general" no_encodings="2" isa="A64">
      <docvars>
        <docvar key="instr-class" value="general" />
        <docvar key="isa" value="A64" />
        <docvar key="mnemonic" value="CLS" />
      </docvars>
      <iclassintro count="2"></iclassintro>
      <regdiagram form="32" psname="aarch64/instrs/integer/arithmetic/cnt" tworows="1">
        <box hibit="31" name="sf" usename="1">
          <c></c>
        </box>
        <box hibit="30" settings="1">
          <c>1</c>
        </box>
        <box hibit="29" name="S" settings="1">
          <c>0</c>
        </box>
        <box hibit="28" width="8" settings="8">
          <c>1</c>
          <c>1</c>
          <c>0</c>
          <c>1</c>
          <c>0</c>
          <c>1</c>
          <c>1</c>
          <c>0</c>
        </box>
        <box hibit="20" width="5" name="opcode2" settings="5">
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="15" width="5" name="opcode[5:1]" settings="5">
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>1</c>
          <c>0</c>
        </box>
        <box hibit="10" name="op" usename="1" settings="1" psbits="x">
          <c>1</c>
        </box>
        <box hibit="9" width="5" name="Rn" usename="1">
          <c colspan="5"></c>
        </box>
        <box hibit="4" width="5" name="Rd" usename="1">
          <c colspan="5"></c>
        </box>
      </regdiagram>
      <encoding name="CLS_32_dp_1src" oneofinclass="2" oneof="2" label="32-bit" bitdiffs="sf == 0">
        <docvars>
          <docvar key="datatype" value="32" />
          <docvar key="instr-class" value="general" />
          <docvar key="isa" value="A64" />
          <docvar key="mnemonic" value="CLS" />
        </docvars>
        <box hibit="31" width="1" name="sf">
          <c>0</c>
        </box>
        <asmtemplate><text>CLS  </text><a link="sa_wd" hover="32-bit general-purpose destination register (field &quot;Rd&quot;)">&lt;Wd&gt;</a><text>, </text><a link="sa_wn" hover="32-bit general-purpose source register (field &quot;Rn&quot;)">&lt;Wn&gt;</a></asmtemplate>
      </encoding>
      <encoding name="CLS_64_dp_1src" oneofinclass="2" oneof="2" label="64-bit" bitdiffs="sf == 1">
        <docvars>
          <docvar key="datatype" value="64" />
          <docvar key="instr-class" value="general" />
          <docvar key="isa" value="A64" />
          <docvar key="mnemonic" value="CLS" />
        </docvars>
        <box hibit="31" width="1" name="sf">
          <c>1</c>
        </box>
        <asmtemplate><text>CLS  </text><a link="sa_xd" hover="64-bit general-purpose destination register (field &quot;Rd&quot;)">&lt;Xd&gt;</a><text>, </text><a link="sa_xn" hover="64-bit general-purpose source register (field &quot;Rn&quot;)">&lt;Xn&gt;</a></asmtemplate>
      </encoding>
      <ps_section howmany="1">
        <ps name="aarch64/instrs/integer/arithmetic/cnt" mylink="aarch64.instrs.integer.arithmetic.cnt" enclabels="" sections="1" secttype="noheading">
          <pstext mayhavelinks="1" section="Decode" rep_section="decode">integer d = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rd);
integer n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn);
integer datasize = if sf == '1' then 64 else 32;
<a link="CountOp" file="shared_pseudocode.xml" hover="enumeration CountOp     {CountOp_CLZ, CountOp_CLS, CountOp_CNT}">CountOp</a> opcode = if op == '0' then <a link="CountOp_CLZ" file="shared_pseudocode.xml" hover="enumeration CountOp     {CountOp_CLZ, CountOp_CLS, CountOp_CNT}">CountOp_CLZ</a> else <a link="CountOp_CLS" file="shared_pseudocode.xml" hover="enumeration CountOp     {CountOp_CLZ, CountOp_CLS, CountOp_CNT}">CountOp_CLS</a>;</pstext>
        </ps>
      </ps_section>
    </iclass>
  </classes>
  <explanations scope="all">
    <explanation enclist="CLS_32_dp_1src" symboldefcount="1">
      <symbol link="sa_wd">&lt;Wd&gt;</symbol>
      <account encodedin="Rd">
        <intro>
          <para>Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="CLS_32_dp_1src" symboldefcount="1">
      <symbol link="sa_wn">&lt;Wn&gt;</symbol>
      <account encodedin="Rn">
        <intro>
          <para>Is the 32-bit name of the general-purpose source register, encoded in the "Rn" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="CLS_64_dp_1src" symboldefcount="1">
      <symbol link="sa_xd">&lt;Xd&gt;</symbol>
      <account encodedin="Rd">
        <intro>
          <para>Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="CLS_64_dp_1src" symboldefcount="1">
      <symbol link="sa_xn">&lt;Xn&gt;</symbol>
      <account encodedin="Rn">
        <intro>
          <para>Is the 64-bit name of the general-purpose source register, encoded in the "Rn" field.</para>
        </intro>
      </account>
    </explanation>
  </explanations>
  <ps_section howmany="1">
    <ps name="aarch64/instrs/integer/arithmetic/cnt" mylink="execute" enclabels="" sections="1" secttype="Operation">
      <pstext mayhavelinks="1" section="Execute" rep_section="execute">integer result;
bits(datasize) operand1 = <a link="impl-aarch64.X.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) X[integer n, integer width]">X</a>[n, datasize];

if opcode == <a link="CountOp_CLZ" file="shared_pseudocode.xml" hover="enumeration CountOp     {CountOp_CLZ, CountOp_CLS, CountOp_CNT}">CountOp_CLZ</a> then
    result = <a link="impl-shared.CountLeadingZeroBits.1" file="shared_pseudocode.xml" hover="function: integer CountLeadingZeroBits(bits(N) x)">CountLeadingZeroBits</a>(operand1);
else
    result = <a link="impl-shared.CountLeadingSignBits.1" file="shared_pseudocode.xml" hover="function: integer CountLeadingSignBits(bits(N) x)">CountLeadingSignBits</a>(operand1);

<a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[d, datasize] = result&lt;datasize-1:0&gt;;</pstext>
    </ps>
  </ps_section>
</instructionsection>
