LDARB

Load-Acquire 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 instruction also has memory ordering semantics as described in Load-Acquire, Store-Release. For information about memory accesses, see Load/Store addressing modes.

For this instruction, if the destination is WZR/ZXR, it is impossible for software to observe the presence of the acquire semantic other than its effect on the arrival at endpoints.

313029282726252423222120191817161514131211109876543210
00001000110(1)(1)(1)(1)(1)1(1)(1)(1)(1)(1)RnRt
sizeLRso0Rt2

No offset

LDARB <Wt>, [<Xn|SP>{,#0}]

integer n = UInt(Rn); integer t = UInt(Rt);

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.

Operation

bits(64) address; bits(8) data; if n == 31 then CheckSPAlignment(); address = SP[]; else address = X[n]; data = Mem[address, 1, AccType_ORDERED]; X[t] = ZeroExtend(data, 32);

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 v29.05, AdvSIMD v26.0, pseudocode v35.3 ; Build timestamp: 2018-06-16T09:58

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