UMULL, UMULLS Unsigned Multiply Long Unsigned Multiply Long multiplies two 32-bit unsigned values to produce a 64-bit result. In A32 instructions, the condition flags can optionally be updated based on the result. Use of this option adversely affects performance on many implementations. For more information about the constrained unpredictable behavior of this instruction, see Architectural Constraints on UNPREDICTABLE behaviors. If CPSR.DIT is 1, this instruction has passed its condition execution check, and does not use R15 as either its source or destination: The execution time of this instruction is independent of:The values of the data supplied in any of its registers.The values of the NZCV flags. The response of this instruction to asynchronous exceptions does not vary based on:The values of the data supplied in any of its registers.The values of the NZCV flags. It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) . != 1111 0 0 0 0 1 0 0 1 0 0 1 1 UMULLS{<c>}{<q>} <RdLo>, <RdHi>, <Rn>, <Rm> 0 UMULL{<c>}{<q>} <RdLo>, <RdHi>, <Rn>, <Rm> dLo = UInt(RdLo); dHi = UInt(RdHi); n = UInt(Rn); m = UInt(Rm); setflags = (S == '1'); if dLo == 15 || dHi == 15 || n == 15 || m == 15 then UNPREDICTABLE; if dHi == dLo then UNPREDICTABLE; dHi == dLo 1 1 1 1 1 0 1 1 1 0 1 0 0 0 0 0 UMULL{<c>}{<q>} <RdLo>, <RdHi>, <Rn>, <Rm> dLo = UInt(RdLo); dHi = UInt(RdHi); n = UInt(Rn); m = UInt(Rm); setflags = FALSE; if dLo == 15 || dHi == 15 || n == 15 || m == 15 then UNPREDICTABLE; // Armv8-A removes UNPREDICTABLE for R13 if dHi == dLo then UNPREDICTABLE; dHi == dLo <c> See Standard assembler syntax fields. <q> See Standard assembler syntax fields. <RdLo> Is the general-purpose destination register for the lower 32 bits of the result, encoded in the "RdLo" field. <RdHi> Is the general-purpose destination register for the upper 32 bits of the result, encoded in the "RdHi" field. <Rn> Is the first general-purpose source register holding the multiplicand, encoded in the "Rn" field. <Rm> Is the second general-purpose source register holding the multiplier, encoded in the "Rm" field. if ConditionPassed() then EncodingSpecificOperations(); result = UInt(R[n]) * UInt(R[m]); R[dHi] = result<63:32>; R[dLo] = result<31:0>; if setflags then PSTATE.N = result<63>; PSTATE.Z = IsZeroBit(result<63:0>); // PSTATE.C, PSTATE.V unchanged