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.
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| sf | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | Rn | Rd | ||||||||
| S | opcode2 | opcode | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_CSSC) then EndOfDecode(Decode_UNDEF); 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>;
If PSTATE.DIT is 1:
Internal version only: aarchmrs v2024-12_rel, pseudocode v2024-12_rel ; Build timestamp: 2024-12-15T22:18
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