ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

Instruction Details
A8.6.291 VCLZ
Vector Count Leading Zeros counts the number of consecutive zeros, starting from the most significant bit,
in each element in a vector, and places the results in a second vector.
The operand vector elements can be any one of 8-bit, 16-bit, or 32-bit integers. There is no distinction
between signed and unsigned integers.
The result vector elements are the same data type as the operand vector elements.
Encoding T1 / A1 Advanced SIMD
VCLZ. ,
VCLZ. ,
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 1 1 1 1 1 1 1 1 D 1 1 size 0 0 Vd 0 1 0 0 1 Q M 0 Vm
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
1 1 1 1 0 0 1 1 1 D 1 1 size 0 0 Vd 0 1 0 0 1 Q M 0 Vm
if size == ‘11’ then UNDEFINED;
if Q == ‘1’ && (Vd == ‘1’ || Vm == ‘1’) then UNDEFINED;
esize = 8