REV Reverse bytes This instruction reverses the byte order in a register. This instruction is a data-independent-time instruction as described in About PSTATE.DIT. This instruction is used by the alias REV64 Never See below for details of when the alias is preferred. 1 0 1 1 0 1 0 1 1 0 0 0 0 0 0 0 0 0 0 1 x 0 0 REV <Wd>, <Wn> 1 1 REV <Xd>, <Xn> if opc == '11' && sf == '0' then EndOfDecode(Decode_UNDEF); end; let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let datasize : integer{} = 32 << UInt(sf); let container_size : integer{} = 8 << UInt(opc); <Wd> Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field. <Wn> Is the 32-bit name of the general-purpose source register, encoded in the "Rn" field. <Xd> Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field. <Xn> Is the 64-bit name of the general-purpose source register, encoded in the "Rn" field. Alias Conditions let operand : bits(datasize) = X{}(n); var result : bits(datasize); let containers : integer = datasize DIV container_size; for c = 0 to containers-1 do let container : bits(container_size) = operand[c*:container_size]; result[c*:container_size] = Reverse{container_size}(container, 8); end; X{datasize}(d) = result; 2026-03-26 20:27:25 2026-03_rel