Count Leading Zeros counts the number of binary zero bits before the first binary one bit in the value of the source register, and writes the result to 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 | 0 | 0 | Rn | Rd | ||||||||
| op | |||||||||||||||||||||||||||||||
integer d = UInt(Rd); integer n = UInt(Rn); integer datasize = if sf == '1' then 64 else 32; CountOp opcode = if op == '0' then CountOp_CLZ else CountOp_CLS;
| <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. |
integer result; bits(datasize) operand1 = X[n]; if opcode == CountOp_CLZ then result = CountLeadingZeroBits(operand1); else result = CountLeadingSignBits(operand1); X[d] = result<datasize-1:0>;
If PSTATE.DIT is 1:
Internal version only: isa v33.11seprel, AdvSIMD v29.05, pseudocode v2021-09_rel, sve v2021-09_rc3d ; Build timestamp: 2021-10-06T11:41
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