LDURSH

Load Register Signed Halfword (unscaled) calculates an address from a base register and an immediate offset, loads a signed halfword from memory, sign-extends it, and writes it to a register. For information about addressing modes, see Load/Store addressing modes.

313029282726252423222120191817161514131211109876543210
011110001x0imm900RnRt
sizeVRopc

32-bit (opc == 11)

LDURSH <Wt>, [<Xn|SP>{, #<simm>}]

64-bit (opc == 10)

LDURSH <Xt>, [<Xn|SP>{, #<simm>}]

bits(64) offset = SignExtend(imm9, 64);

Assembler Symbols

<Wt>

Is the 32-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.

<Xt>

Is the 64-bit name of the general-purpose register to be transferred, encoded in the "Rt" field.

Shared Decode

integer n = UInt(Rn); integer t = UInt(Rt); integer regsize = 64 >> UInt(opc<0>); boolean nontemporal = FALSE; boolean tagchecked = n != 31;

Operation

bits(64) address; boolean privileged = PSTATE.EL != EL0; 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); bits(16) data = Mem[address, 2, accdesc]; X[t, regsize] = SignExtend(data, regsize);

Operational information

If PSTATE.DIT is 1, the timing of this instruction is insensitive to the value of the data being loaded or stored.


Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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