LDURSW
Load register signed word (unscaled)
This instruction calculates an
address from a base
register and an immediate offset, loads a signed word from memory,
sign-extends it, and writes it
to a register. For information about addressing modes, see
Load/Store addressing modes.
If PSTATE.DIT is 1, the timing of this instruction is insensitive to the value of the data being loaded or stored.
1
0
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0
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1
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LDURSW <Xt>, [<Xn|SP>{, #<simm>}]
constant bits(64) offset = SignExtend(imm9, 64);
<Xt>
Is the 64-bit name of the general-purpose register to be transferred, encoded in the "Rt" field.
<Xn|SP>
Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.
<simm>
Is the optional signed immediate byte offset, in the range -256 to 255, defaulting to 0 and encoded in the "imm9" field.
constant integer n = UInt(Rn);
constant integer t = UInt(Rt);
constant integer datasize = 32;
constant boolean nontemporal = FALSE;
constant boolean tagchecked = n != 31;
bits(64) address;
constant boolean privileged = PSTATE.EL != EL0;
constant AccessDescriptor accdesc = CreateAccDescGPR(MemOp_LOAD, nontemporal, privileged,
tagchecked);
if n == 31 then
CheckSPAlignment();
address = SP[];
else
address = X[n, 64];
address = AddressAdd(address, offset, accdesc);
constant bits(datasize) data = Mem[address, datasize DIV 8, accdesc];
X[t, 64] = SignExtend(data, 64);