CTZ Count trailing zeros This instruction counts the number of consecutive binary zero bits, starting from the least significant bit in the source register, and places the count in the destination register. If PSTATE.DIT is 1: 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. 1 0 1 1 0 1 0 1 1 0 0 0 0 0 0 0 0 0 1 1 0 0 CTZ <Wd>, <Wn> 1 CTZ <Xd>, <Xn> if !IsFeatureImplemented(FEAT_CSSC) then UNDEFINED; constant integer datasize = 32 << UInt(sf); constant integer d = UInt(Rd); constant integer n = UInt(Rn); <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. constant bits(datasize) operand1 = X[n, datasize]; constant integer result = CountLeadingZeroBits(BitReverse(operand1)); X[d, datasize] = result<datasize-1:0>;