cls

CLS <Zd>.<T>, <Pg>/M, <Zn>.<T>

Count Leading Sign Bits.

Pseudocode Operation

No pseudocode available.

Encoding

Binary Layout

00000100

31:24

size

23:22

011

21:19

18:17

101

15:13

12:10

9:5

4:0

Format SVE

Opcode 0x0418A000

Extension SVE

Other forms of cls

cls Count Leading Sign Bits, Base

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction	ISA	Bit pattern
0x0E204800	CLS <Vd>.<T>, <Vn>.<T>	A64	0 \| Q \| 0 \| 01110 \| size \| 10000 \| 00100 \| 10 \| Rn \| Rd
0x5AC01400	CLS <Wd>, <Wn>	A64	0 \| 1 \| 0 \| 11010110 \| 00000 \| 00010 \| 1 \| Rn \| Rd
0xDAC01400	CLS <Xd>, <Xn>	A64	1 \| 1 \| 0 \| 11010110 \| 00000 \| 00010 \| 1 \| Rn \| Rd
0x0418A000	CLS <Zd>.<T>, <Pg>/M, <Zn>.<T>	A64	00000100 \| size \| 011 \| 00 \| 0 \| 101 \| Pg \| Zn \| Zd

Description

Count the number of consecutive sign bits, starting from the most significant bit in each active element of the source vector, and place the results in the corresponding elements of the destination vector. Inactive elements in the destination vector register remain unmodified.

Operation

CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
bits(PL) mask = P[g, PL];
bits(VL) operand = if AnyActiveElement(mask, esize) then Z[n, VL] else Zeros(VL);
bits(VL) result = Z[d, VL];

for e = 0 to elements-1
    if ActivePredicateElement(mask, e, esize) then
        bits(esize) element = Elem[operand, e, esize];
        Elem[result, e, esize] = CountLeadingSignBits(element)<esize-1:0>;

Z[d, VL] = result;

cls