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<instructionsection id="LDXRB" title="LDXRB -- A64" type="instruction">
  <docvars>
    <docvar key="address-form" value="base-register" />
    <docvar key="address-form-reg-type" value="base-register-32-reg" />
    <docvar key="atomic-ops" value="LDXRB-32-reg" />
    <docvar key="instr-class" value="general" />
    <docvar key="isa" value="A64" />
    <docvar key="mnemonic" value="LDXRB" />
    <docvar key="reg-type" value="32-reg" />
  </docvars>
  <heading>LDXRB</heading>
  <desc>
    <brief>
      <para>Load Exclusive Register Byte</para>
    </brief>
    <authored>
      <para>Load Exclusive Register Byte derives an address from a base register value, loads a byte from memory, zero-extends it and writes it to a register. The memory access is atomic. The PE marks the physical address being accessed as an exclusive access. This exclusive access mark is checked by Store Exclusive instructions. See <xref linkend="Chdcgdja">Synchronization and semaphores</xref>. For information about memory accesses see <xref linkend="CHDIIIBB">Load/Store addressing modes</xref>.</para>
    </authored>
  </desc>
  <operationalnotes>
    <para>If PSTATE.DIT is 1, the timing of this instruction is insensitive to the value of the data being loaded or stored.</para>
  </operationalnotes>
  <alias_list howmany="0"></alias_list>
  <classes>
    <iclass name="No offset" oneof="1" id="iclass_base_register" no_encodings="1" isa="A64">
      <docvars>
        <docvar key="address-form" value="base-register" />
        <docvar key="address-form-reg-type" value="base-register-32-reg" />
        <docvar key="atomic-ops" value="LDXRB-32-reg" />
        <docvar key="instr-class" value="general" />
        <docvar key="isa" value="A64" />
        <docvar key="mnemonic" value="LDXRB" />
        <docvar key="reg-type" value="32-reg" />
      </docvars>
      <iclassintro count="1"></iclassintro>
      <regdiagram form="32" psname="aarch64/instrs/memory/exclusive/single" tworows="1">
        <box hibit="31" width="2" name="size" usename="1" settings="2" psbits="xx">
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="29" width="6" settings="6">
          <c>0</c>
          <c>0</c>
          <c>1</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="23" name="o2" settings="1">
          <c>0</c>
        </box>
        <box hibit="22" name="L" usename="1" settings="1" psbits="x">
          <c>1</c>
        </box>
        <box hibit="21" name="o1" settings="1">
          <c>0</c>
        </box>
        <box hibit="20" width="5" name="Rs" usename="1" settings="5" psbits="xxxxx">
          <c>(1)</c>
          <c>(1)</c>
          <c>(1)</c>
          <c>(1)</c>
          <c>(1)</c>
        </box>
        <box hibit="15" name="o0" usename="1" settings="1" psbits="x">
          <c>0</c>
        </box>
        <box hibit="14" width="5" name="Rt2" usename="1" settings="5" psbits="xxxxx">
          <c>(1)</c>
          <c>(1)</c>
          <c>(1)</c>
          <c>(1)</c>
          <c>(1)</c>
        </box>
        <box hibit="9" width="5" name="Rn" usename="1">
          <c colspan="5"></c>
        </box>
        <box hibit="4" width="5" name="Rt" usename="1">
          <c colspan="5"></c>
        </box>
      </regdiagram>
      <encoding name="LDXRB_LR32_ldstexclr" oneofinclass="1" oneof="1" label="">
        <docvars>
          <docvar key="address-form" value="base-register" />
          <docvar key="address-form-reg-type" value="base-register-32-reg" />
          <docvar key="atomic-ops" value="LDXRB-32-reg" />
          <docvar key="instr-class" value="general" />
          <docvar key="isa" value="A64" />
          <docvar key="mnemonic" value="LDXRB" />
          <docvar key="reg-type" value="32-reg" />
        </docvars>
        <asmtemplate><text>LDXRB  </text><a link="sa_wt" hover="32-bit general-purpose register to be transferred (field &quot;Rt&quot;)">&lt;Wt&gt;</a><text>, [</text><a link="sa_xn_sp" hover="64-bit general-purpose base register or SP (field &quot;Rn&quot;)">&lt;Xn|SP&gt;</a><text>{,#0}</text><text>]</text></asmtemplate>
      </encoding>
      <ps_section howmany="1">
        <ps name="aarch64/instrs/memory/exclusive/single" mylink="aarch64.instrs.memory.exclusive.single" enclabels="" sections="1" secttype="noheading">
          <pstext mayhavelinks="1" section="Decode" rep_section="decode">integer n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn);
integer t = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rt);
integer t2 = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rt2);    // ignored by load/store single register
integer s = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rs);      // ignored by all loads and store-release

boolean acqrel = o0 == '1';
boolean pair = FALSE;
<a link="MemOp" file="shared_pseudocode.xml" hover="enumeration MemOp {MemOp_LOAD, MemOp_STORE, MemOp_PREFETCH}">MemOp</a> memop = if L == '1' then <a link="MemOp_LOAD" file="shared_pseudocode.xml" hover="enumeration MemOp {MemOp_LOAD, MemOp_STORE, MemOp_PREFETCH}">MemOp_LOAD</a> else <a link="MemOp_STORE" file="shared_pseudocode.xml" hover="enumeration MemOp {MemOp_LOAD, MemOp_STORE, MemOp_PREFETCH}">MemOp_STORE</a>;
integer elsize = 8 &lt;&lt; <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(size);
integer regsize = if elsize == 64 then 64 else 32;
integer datasize = if pair then elsize * 2 else elsize;
boolean tagchecked = n != 31;

boolean rt_unknown = FALSE;
boolean rn_unknown = FALSE;
if memop == <a link="MemOp_LOAD" file="shared_pseudocode.xml" hover="enumeration MemOp {MemOp_LOAD, MemOp_STORE, MemOp_PREFETCH}">MemOp_LOAD</a> &amp;&amp; pair &amp;&amp; t == t2 then
    <a link="Constraint" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint</a> c = <a link="impl-shared.ConstrainUnpredictable.1" file="shared_pseudocode.xml" hover="function: Constraint ConstrainUnpredictable(Unpredictable which)">ConstrainUnpredictable</a>(<a link="Unpredictable_LDPOVERLAP" file="shared_pseudocode.xml" hover="enumeration Unpredictable {  Unpredictable_VMSR,  Unpredictable_WBOVERLAPLD,  Unpredictable_WBOVERLAPST,  Unpredictable_LDPOVERLAP,  Unpredictable_BASEOVERLAP,  Unpredictable_DATAOVERLAP,  Unpredictable_DEVPAGE2,  Unpredictable_INSTRDEVICE,  Unpredictable_RESCPACR,  Unpredictable_RESMAIR,  Unpredictable_S1CTAGGED,  Unpredictable_S2RESMEMATTR,  Unpredictable_RESTEXCB,  Unpredictable_RESPRRR,  Unpredictable_RESDACR,  Unpredictable_RESVTCRS,  Unpredictable_RESTnSZ,  Unpredictable_RESTCF,  Unpredictable_DEVICETAGSTORE,  Unpredictable_OORTnSZ,  Unpredictable_LARGEIPA,  Unpredictable_ESRCONDPASS,  Unpredictable_ILZEROIT,  Unpredictable_ILZEROT,  Unpredictable_BPVECTORCATCHPRI,  Unpredictable_VCMATCHHALF,   Unpredictable_VCMATCHDAPA,  Unpredictable_WPMASKANDBAS,  Unpredictable_WPBASCONTIGUOUS,  Unpredictable_RESWPMASK,  Unpredictable_WPMASKEDBITS,  Unpredictable_RESBPWPCTRL,  Unpredictable_BPNOTIMPL,  Unpredictable_RESBPTYPE,  Unpredictable_BPNOTCTXCMP,  Unpredictable_BPMATCHHALF,  Unpredictable_BPMISMATCHHALF,  Unpredictable_RESTARTALIGNPC,  Unpredictable_RESTARTZEROUPPERPC,  Unpredictable_ZEROUPPER,   Unpredictable_ERETZEROUPPERPC,   Unpredictable_A32FORCEALIGNPC,  Unpredictable_SMD,  Unpredictable_NONFAULT,  Unpredictable_SVEZEROUPPER,  Unpredictable_SVELDNFDATA,  Unpredictable_SVELDNFZERO,  Unpredictable_CHECKSPNONEACTIVE,  Unpredictable_SMEZEROUPPER,  Unpredictable_NVNV1,  Unpredictable_Shareability,  Unpredictable_AFUPDATE,  Unpredictable_DBUPDATE,  Unpredictable_IESBinDebug,  Unpredictable_BADPMSFCR,  Unpredictable_ZEROBTYPE,  Unpredictable_EL2TIMESTAMP, Unpredictable_EL1TIMESTAMP,  Unpredictable_RESERVEDNSxB,  Unpredictable_WFxTDEBUG,  Unpredictable_LS64UNSUPPORTED,   Unpredictable_MISALIGNEDATOMIC,  Unpredictable_CLEARERRITEZERO,   Unpredictable_ALUEXCEPTIONRETURN,  Unpredictable_IGNORETRAPINDEBUG,  Unpredictable_DBGxVR_RESS,  Unpredictable_PMUEVENTCOUNTER,  Unpredictable_PMSCR_PCT,   Unpredictable_CounterReservedForEL2,  Unpredictable_BRBFILTRATE,   Unpredictable_MOPSOVERLAP31,  Unpredictable_STOREONLYTAGCHECKEDCAS,  Unpredictable_RESTC }">Unpredictable_LDPOVERLAP</a>);
    assert c IN {<a link="Constraint_UNKNOWN" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNKNOWN</a>, <a link="Constraint_UNDEF" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNDEF</a>, <a link="Constraint_NOP" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_NOP</a>};
    case c of
        when <a link="Constraint_UNKNOWN" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNKNOWN</a>    rt_unknown = TRUE;    // result is UNKNOWN
        when <a link="Constraint_UNDEF" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNDEF</a>      UNDEFINED;
        when <a link="Constraint_NOP" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_NOP</a>        <a link="impl-shared.EndOfInstruction.0" file="shared_pseudocode.xml" hover="function: EndOfInstruction()">EndOfInstruction</a>();

if memop == <a link="MemOp_STORE" file="shared_pseudocode.xml" hover="enumeration MemOp {MemOp_LOAD, MemOp_STORE, MemOp_PREFETCH}">MemOp_STORE</a> then
    if s == t || (pair &amp;&amp; s == t2) then
        <a link="Constraint" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint</a> c = <a link="impl-shared.ConstrainUnpredictable.1" file="shared_pseudocode.xml" hover="function: Constraint ConstrainUnpredictable(Unpredictable which)">ConstrainUnpredictable</a>(<a link="Unpredictable_DATAOVERLAP" file="shared_pseudocode.xml" hover="enumeration Unpredictable {  Unpredictable_VMSR,  Unpredictable_WBOVERLAPLD,  Unpredictable_WBOVERLAPST,  Unpredictable_LDPOVERLAP,  Unpredictable_BASEOVERLAP,  Unpredictable_DATAOVERLAP,  Unpredictable_DEVPAGE2,  Unpredictable_INSTRDEVICE,  Unpredictable_RESCPACR,  Unpredictable_RESMAIR,  Unpredictable_S1CTAGGED,  Unpredictable_S2RESMEMATTR,  Unpredictable_RESTEXCB,  Unpredictable_RESPRRR,  Unpredictable_RESDACR,  Unpredictable_RESVTCRS,  Unpredictable_RESTnSZ,  Unpredictable_RESTCF,  Unpredictable_DEVICETAGSTORE,  Unpredictable_OORTnSZ,  Unpredictable_LARGEIPA,  Unpredictable_ESRCONDPASS,  Unpredictable_ILZEROIT,  Unpredictable_ILZEROT,  Unpredictable_BPVECTORCATCHPRI,  Unpredictable_VCMATCHHALF,   Unpredictable_VCMATCHDAPA,  Unpredictable_WPMASKANDBAS,  Unpredictable_WPBASCONTIGUOUS,  Unpredictable_RESWPMASK,  Unpredictable_WPMASKEDBITS,  Unpredictable_RESBPWPCTRL,  Unpredictable_BPNOTIMPL,  Unpredictable_RESBPTYPE,  Unpredictable_BPNOTCTXCMP,  Unpredictable_BPMATCHHALF,  Unpredictable_BPMISMATCHHALF,  Unpredictable_RESTARTALIGNPC,  Unpredictable_RESTARTZEROUPPERPC,  Unpredictable_ZEROUPPER,   Unpredictable_ERETZEROUPPERPC,   Unpredictable_A32FORCEALIGNPC,  Unpredictable_SMD,  Unpredictable_NONFAULT,  Unpredictable_SVEZEROUPPER,  Unpredictable_SVELDNFDATA,  Unpredictable_SVELDNFZERO,  Unpredictable_CHECKSPNONEACTIVE,  Unpredictable_SMEZEROUPPER,  Unpredictable_NVNV1,  Unpredictable_Shareability,  Unpredictable_AFUPDATE,  Unpredictable_DBUPDATE,  Unpredictable_IESBinDebug,  Unpredictable_BADPMSFCR,  Unpredictable_ZEROBTYPE,  Unpredictable_EL2TIMESTAMP, Unpredictable_EL1TIMESTAMP,  Unpredictable_RESERVEDNSxB,  Unpredictable_WFxTDEBUG,  Unpredictable_LS64UNSUPPORTED,   Unpredictable_MISALIGNEDATOMIC,  Unpredictable_CLEARERRITEZERO,   Unpredictable_ALUEXCEPTIONRETURN,  Unpredictable_IGNORETRAPINDEBUG,  Unpredictable_DBGxVR_RESS,  Unpredictable_PMUEVENTCOUNTER,  Unpredictable_PMSCR_PCT,   Unpredictable_CounterReservedForEL2,  Unpredictable_BRBFILTRATE,   Unpredictable_MOPSOVERLAP31,  Unpredictable_STOREONLYTAGCHECKEDCAS,  Unpredictable_RESTC }">Unpredictable_DATAOVERLAP</a>);
        assert c IN {<a link="Constraint_UNKNOWN" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNKNOWN</a>, <a link="Constraint_UNDEF" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNDEF</a>, <a link="Constraint_NOP" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_NOP</a>};
        case c of
            when <a link="Constraint_UNKNOWN" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNKNOWN</a>    rt_unknown = TRUE;    // store UNKNOWN value
            when <a link="Constraint_UNDEF" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNDEF</a>      UNDEFINED;
            when <a link="Constraint_NOP" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_NOP</a>        <a link="impl-shared.EndOfInstruction.0" file="shared_pseudocode.xml" hover="function: EndOfInstruction()">EndOfInstruction</a>();
    if s == n &amp;&amp; n != 31 then
        <a link="Constraint" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint</a> c = <a link="impl-shared.ConstrainUnpredictable.1" file="shared_pseudocode.xml" hover="function: Constraint ConstrainUnpredictable(Unpredictable which)">ConstrainUnpredictable</a>(<a link="Unpredictable_BASEOVERLAP" file="shared_pseudocode.xml" hover="enumeration Unpredictable {  Unpredictable_VMSR,  Unpredictable_WBOVERLAPLD,  Unpredictable_WBOVERLAPST,  Unpredictable_LDPOVERLAP,  Unpredictable_BASEOVERLAP,  Unpredictable_DATAOVERLAP,  Unpredictable_DEVPAGE2,  Unpredictable_INSTRDEVICE,  Unpredictable_RESCPACR,  Unpredictable_RESMAIR,  Unpredictable_S1CTAGGED,  Unpredictable_S2RESMEMATTR,  Unpredictable_RESTEXCB,  Unpredictable_RESPRRR,  Unpredictable_RESDACR,  Unpredictable_RESVTCRS,  Unpredictable_RESTnSZ,  Unpredictable_RESTCF,  Unpredictable_DEVICETAGSTORE,  Unpredictable_OORTnSZ,  Unpredictable_LARGEIPA,  Unpredictable_ESRCONDPASS,  Unpredictable_ILZEROIT,  Unpredictable_ILZEROT,  Unpredictable_BPVECTORCATCHPRI,  Unpredictable_VCMATCHHALF,   Unpredictable_VCMATCHDAPA,  Unpredictable_WPMASKANDBAS,  Unpredictable_WPBASCONTIGUOUS,  Unpredictable_RESWPMASK,  Unpredictable_WPMASKEDBITS,  Unpredictable_RESBPWPCTRL,  Unpredictable_BPNOTIMPL,  Unpredictable_RESBPTYPE,  Unpredictable_BPNOTCTXCMP,  Unpredictable_BPMATCHHALF,  Unpredictable_BPMISMATCHHALF,  Unpredictable_RESTARTALIGNPC,  Unpredictable_RESTARTZEROUPPERPC,  Unpredictable_ZEROUPPER,   Unpredictable_ERETZEROUPPERPC,   Unpredictable_A32FORCEALIGNPC,  Unpredictable_SMD,  Unpredictable_NONFAULT,  Unpredictable_SVEZEROUPPER,  Unpredictable_SVELDNFDATA,  Unpredictable_SVELDNFZERO,  Unpredictable_CHECKSPNONEACTIVE,  Unpredictable_SMEZEROUPPER,  Unpredictable_NVNV1,  Unpredictable_Shareability,  Unpredictable_AFUPDATE,  Unpredictable_DBUPDATE,  Unpredictable_IESBinDebug,  Unpredictable_BADPMSFCR,  Unpredictable_ZEROBTYPE,  Unpredictable_EL2TIMESTAMP, Unpredictable_EL1TIMESTAMP,  Unpredictable_RESERVEDNSxB,  Unpredictable_WFxTDEBUG,  Unpredictable_LS64UNSUPPORTED,   Unpredictable_MISALIGNEDATOMIC,  Unpredictable_CLEARERRITEZERO,   Unpredictable_ALUEXCEPTIONRETURN,  Unpredictable_IGNORETRAPINDEBUG,  Unpredictable_DBGxVR_RESS,  Unpredictable_PMUEVENTCOUNTER,  Unpredictable_PMSCR_PCT,   Unpredictable_CounterReservedForEL2,  Unpredictable_BRBFILTRATE,   Unpredictable_MOPSOVERLAP31,  Unpredictable_STOREONLYTAGCHECKEDCAS,  Unpredictable_RESTC }">Unpredictable_BASEOVERLAP</a>);
        assert c IN {<a link="Constraint_UNKNOWN" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNKNOWN</a>, <a link="Constraint_UNDEF" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNDEF</a>, <a link="Constraint_NOP" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_NOP</a>};
        case c of
            when <a link="Constraint_UNKNOWN" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNKNOWN</a>    rn_unknown = TRUE;    // address is UNKNOWN
            when <a link="Constraint_UNDEF" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_UNDEF</a>      UNDEFINED;
            when <a link="Constraint_NOP" file="shared_pseudocode.xml" hover="enumeration Constraint    { Constraint_NONE,   Constraint_UNKNOWN,  Constraint_UNDEF, Constraint_UNDEFEL0, Constraint_NOP, Constraint_TRUE, Constraint_FALSE, Constraint_DISABLED, Constraint_UNCOND, Constraint_COND, Constraint_ADDITIONAL_DECODE,   Constraint_WBSUPPRESS, Constraint_FAULT, Constraint_LIMITED_ATOMICITY,   Constraint_NVNV1_00, Constraint_NVNV1_01, Constraint_NVNV1_11, Constraint_EL1TIMESTAMP, Constraint_EL2TIMESTAMP, Constraint_OSH, Constraint_ISH, Constraint_NSH,  Constraint_NC, Constraint_WT, Constraint_WB,   Constraint_FORCE, Constraint_FORCENOSLCHECK,  Constraint_MAPTOALLOCATED,  Constraint_PMSCR_PCT_VIRT }">Constraint_NOP</a>        <a link="impl-shared.EndOfInstruction.0" file="shared_pseudocode.xml" hover="function: EndOfInstruction()">EndOfInstruction</a>();</pstext>
        </ps>
      </ps_section>
    </iclass>
  </classes>
  <explanations scope="all">
    <explanation enclist="LDXRB_LR32_ldstexclr" symboldefcount="1">
      <symbol link="sa_wt">&lt;Wt&gt;</symbol>
      <account encodedin="Rt">
        <intro>
          <para>Is the 32-bit name of the general-purpose register to be transferred, encoded in the "Rt" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="LDXRB_LR32_ldstexclr" symboldefcount="1">
      <symbol link="sa_xn_sp">&lt;Xn|SP&gt;</symbol>
      <account encodedin="Rn">
        <intro>
          <para>Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.</para>
        </intro>
      </account>
    </explanation>
  </explanations>
  <ps_section howmany="1">
    <ps name="aarch64/instrs/memory/exclusive/single" mylink="execute" enclabels="" sections="1" secttype="Operation">
      <pstext mayhavelinks="1" section="Execute" rep_section="execute">bits(64) address;
bits(datasize) data;
constant integer dbytes = datasize DIV 8;

<a link="AccessDescriptor" file="shared_pseudocode.xml" hover="type AccessDescriptor is ( AccessType acctype, bits(2) el, SecurityState ss, boolean acqsc, boolean acqpc, boolean relsc, boolean limitedordered, boolean exclusive, boolean atomicop, MemAtomicOp modop, boolean nontemporal, boolean read, boolean write, CacheOp cacheop, CacheOpScope opscope, CacheType cachetype, boolean pan, boolean transactional, boolean nonfault, boolean firstfault, boolean first, boolean contiguous, boolean streamingsve, boolean ls64, boolean mops, boolean rcw, boolean rcws, boolean toplevel, VARange varange, boolean a32lsmd, boolean tagchecked, boolean tagaccess, MPAMinfo mpam )">AccessDescriptor</a> accdesc = <a link="impl-shared.CreateAccDescExLDST.3" file="shared_pseudocode.xml" hover="function: AccessDescriptor CreateAccDescExLDST(MemOp memop, boolean acqrel, boolean tagchecked)">CreateAccDescExLDST</a>(memop, acqrel, tagchecked);

if n == 31 then
    <a link="impl-aarch64.CheckSPAlignment.0" file="shared_pseudocode.xml" hover="function: CheckSPAlignment()">CheckSPAlignment</a>();
    address = <a link="impl-aarch64.SP.read.0" file="shared_pseudocode.xml" hover="accessor: bits(64) SP[]">SP</a>[];
elsif rn_unknown then
    address = bits(64) UNKNOWN;
else
    address = <a link="impl-aarch64.X.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) X[integer n, integer width]">X</a>[n, 64];

case memop of
    when <a link="MemOp_STORE" file="shared_pseudocode.xml" hover="enumeration MemOp {MemOp_LOAD, MemOp_STORE, MemOp_PREFETCH}">MemOp_STORE</a>
        if rt_unknown then
            data = bits(datasize) UNKNOWN;
        elsif pair then
            bits(datasize DIV 2) el1 = <a link="impl-aarch64.X.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) X[integer n, integer width]">X</a>[t, datasize DIV 2];
            bits(datasize DIV 2) el2 = <a link="impl-aarch64.X.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) X[integer n, integer width]">X</a>[t2, datasize DIV 2];
            data = if <a link="impl-shared.BigEndian.1" file="shared_pseudocode.xml" hover="function: boolean BigEndian(AccessType acctype)">BigEndian</a>(accdesc.acctype) then el1 : el2 else el2 : el1;
        else
            data = <a link="impl-aarch64.X.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) X[integer n, integer width]">X</a>[t, datasize];

        bit status = '1';
        // Check whether the Exclusives monitors are set to include the
        // physical memory locations corresponding to virtual address
        // range [address, address+dbytes-1].

        // If AArch64.ExclusiveMonitorsPass() returns FALSE and the memory address,
        // if accessed, would generate a synchronous Data Abort exception, it is
        // IMPLEMENTATION DEFINED whether the exception is generated.
        // It is a limitation of this model that synchronous Data Aborts are never
        // generated in this case, as Mem[] is not called.
        // If FEAT_SPE is implemented, it is also IMPLEMENTATION DEFINED whether or not the
        // physical address packet is output when permitted and when
        // AArch64.ExclusiveMonitorPass() returns FALSE for a Store Exclusive instruction.
        // This behavior is not reflected here due to the previously stated limitation.
        if <a link="AArch64.ExclusiveMonitorsPass.2" file="shared_pseudocode.xml" hover="function: boolean AArch64.ExclusiveMonitorsPass(bits(64) address, integer size)">AArch64.ExclusiveMonitorsPass</a>(address, dbytes) then
            // This atomic write will be rejected if it does not refer
            // to the same physical locations after address translation.
            Mem[address, dbytes, accdesc] = data;
            status = <a link="impl-shared.ExclusiveMonitorsStatus.0" file="shared_pseudocode.xml" hover="function: bit ExclusiveMonitorsStatus()">ExclusiveMonitorsStatus</a>();
        <a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[s, 32] = <a link="impl-shared.ZeroExtend.2" file="shared_pseudocode.xml" hover="function: bits(N) ZeroExtend(bits(M) x, integer N)">ZeroExtend</a>(status, 32);

    when <a link="MemOp_LOAD" file="shared_pseudocode.xml" hover="enumeration MemOp {MemOp_LOAD, MemOp_STORE, MemOp_PREFETCH}">MemOp_LOAD</a>
        // Tell the Exclusives monitors to record a sequence of one or more atomic
        // memory reads from virtual address range [address, address+dbytes-1].
        // The Exclusives monitor will only be set if all the reads are from the
        // same dbytes-aligned physical address, to allow for the possibility of
        // an atomicity break if the translation is changed between reads.
        <a link="AArch64.SetExclusiveMonitors.2" file="shared_pseudocode.xml" hover="function: AArch64.SetExclusiveMonitors(bits(64) address, integer size)">AArch64.SetExclusiveMonitors</a>(address, dbytes);

        if pair then
            if rt_unknown then
                // ConstrainedUNPREDICTABLE case
                <a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[t, datasize]  = bits(datasize) UNKNOWN;        // In this case t = t2
            elsif elsize == 32 then
                // 32-bit load exclusive pair (atomic)
                data = <a link="impl-aarch64.Mem.read.3" file="shared_pseudocode.xml" hover="accessor: bits(size*8) Mem[bits(64) address, integer size, AccessDescriptor accdesc]">Mem</a>[address, dbytes, accdesc];
                if <a link="impl-shared.BigEndian.1" file="shared_pseudocode.xml" hover="function: boolean BigEndian(AccessType acctype)">BigEndian</a>(accdesc.acctype) then
                    <a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[t, datasize - elsize] = data&lt;datasize-1:elsize&gt;;
                    <a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[t2, elsize] = data&lt;elsize-1:0&gt;;
                else
                    <a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[t, elsize]  = data&lt;elsize-1:0&gt;;
                    <a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[t2, datasize - elsize] = data&lt;datasize-1:elsize&gt;;
            else // elsize == 64
                // 64-bit load exclusive pair (not atomic), but must be 128-bit aligned
                if !<a link="impl-shared.IsAligned.2" file="shared_pseudocode.xml" hover="function: boolean IsAligned(integer x, integer y)">IsAligned</a>(address, dbytes) then
                    <a link="AArch64.Abort.2" file="shared_pseudocode.xml" hover="function: AArch64.Abort(bits(64) vaddress, FaultRecord fault)">AArch64.Abort</a>(address, <a link="impl-shared.AlignmentFault.1" file="shared_pseudocode.xml" hover="function: FaultRecord AlignmentFault(AccessDescriptor accdesc)">AlignmentFault</a>(accdesc));

                <a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[t, 64]  = <a link="impl-aarch64.Mem.read.3" file="shared_pseudocode.xml" hover="accessor: bits(size*8) Mem[bits(64) address, integer size, AccessDescriptor accdesc]">Mem</a>[address + 0, 8, accdesc];
                <a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[t2, 64] = <a link="impl-aarch64.Mem.read.3" file="shared_pseudocode.xml" hover="accessor: bits(size*8) Mem[bits(64) address, integer size, AccessDescriptor accdesc]">Mem</a>[address + 8, 8, accdesc];
        else
            data = <a link="impl-aarch64.Mem.read.3" file="shared_pseudocode.xml" hover="accessor: bits(size*8) Mem[bits(64) address, integer size, AccessDescriptor accdesc]">Mem</a>[address, dbytes, accdesc];
            <a link="impl-aarch64.X.write.2" file="shared_pseudocode.xml" hover="accessor: X[integer n, integer width] = bits(width) value">X</a>[t, regsize] = <a link="impl-shared.ZeroExtend.2" file="shared_pseudocode.xml" hover="function: bits(N) ZeroExtend(bits(M) x, integer N)">ZeroExtend</a>(data, regsize);</pstext>
    </ps>
  </ps_section>
</instructionsection>
