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>;
Internal version only: isa v32.13, AdvSIMD v29.04, pseudocode morello-2022-01_rc2, capabilities morello-2022-01_rc2 ; Build timestamp: 2022-01-11T11:23
Copyright © 2010-2022 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.