QSUB16 Saturating Subtract 16 Saturating Subtract 16 performs two 16-bit integer subtractions, saturates the results to the 16-bit signed integer range -2¹⁵ <= x <= 2¹⁵ - 1, and writes the results to the destination register. For more information about the constrained unpredictable behavior of this instruction, see Architectural Constraints on UNPREDICTABLE behaviors. It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) . != 1111 0 1 1 0 0 0 1 0 (1) (1) (1) (1) 0 1 1 1 QSUB16{<c>}{<q>} {<Rd>,} <Rn>, <Rm> d = UInt(Rd); n = UInt(Rn); m = UInt(Rm); if d == 15 || n == 15 || m == 15 then UNPREDICTABLE; 1 1 1 1 1 0 1 0 1 1 0 1 1 1 1 1 0 0 0 1 QSUB16{<c>}{<q>} {<Rd>,} <Rn>, <Rm> d = UInt(Rd); n = UInt(Rn); m = UInt(Rm); if d == 15 || n == 15 || m == 15 then UNPREDICTABLE; // Armv8-A removes UNPREDICTABLE for R13 <c> See Standard assembler syntax fields. <q> See Standard assembler syntax fields. <Rd> Is the general-purpose destination register, encoded in the "Rd" field. <Rn> Is the first general-purpose source register, encoded in the "Rn" field. <Rm> Is the second general-purpose source register, encoded in the "Rm" field. if ConditionPassed() then EncodingSpecificOperations(); diff1 = SInt(R[n]<15:0>) - SInt(R[m]<15:0>); diff2 = SInt(R[n]<31:16>) - SInt(R[m]<31:16>); R[d]<15:0> = SignedSat(diff1, 16); R[d]<31:16> = SignedSat(diff2, 16);