STTRH

Store Register Halfword (unprivileged) stores a halfword from a 32-bit register to memory. The address that is used for the store is calculated from a base register and an immediate offset.

Memory accesses made by the instruction behave as if the instruction was executed at EL0 if the Effective value of PSTATE.UAO is 0 and either:

Otherwise, the memory access operates with the restrictions determined by the Exception level at which the instruction is executed. For information about memory accesses, see Load/Store addressing modes.

313029282726252423222120191817161514131211109876543210
01111000000imm910RnRt
sizeopc

Unscaled offset

STTRH <Wt>, [<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.

Shared Decode

integer n = UInt(Rn); integer t = UInt(Rt); unpriv_at_el1 = PSTATE.EL == EL1 && !(EL2Enabled() && HaveNVExt() && HCR_EL2.<NV,NV1> == '11'); unpriv_at_el2 = HaveEL(EL2) && HaveVirtHostExt() && PSTATE.EL == EL2 && HCR_EL2.<E2H,TGE> == '11'; user_access_override = HaveUAOExt() && PSTATE.UAO == '1'; if !user_access_override && (unpriv_at_el1 || unpriv_at_el2) then acctype = AccType_UNPRIV; else acctype = AccType_NORMAL;

Operation

if HaveMTEExt() then boolean is_load_store = MemOp_STORE IN {MemOp_STORE, MemOp_LOAD}; SetNotTagCheckedInstruction(is_load_store && n == 31); bits(64) address; bits(16) data; if n == 31 then CheckSPAlignment(); address = SP[]; else address = X[n]; address = address + offset; data = X[t]; Mem[address, 2, acctype] = data;

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: isa v30.25, AdvSIMD v27.01, pseudocode v85-xml-00bet8_rc3 ; Build timestamp: 2018-09-13T13:25

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