cntb

CNTB <Xd>{, <pattern>{, MUL #<imm>}}

Count Bytes in Vector.

Pseudocode Operation

No pseudocode available.

Encoding

Binary Layout

00000100

31:24

21:20

imm4

19:16

11100

15:11

pattern

9:5

4:0

Format SVE

Opcode 0x0420E000

Extension SVE

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x0420E000	CNTB <Xd>{, <pattern>{, MUL #<imm>}}		A64		00000100 \| 0 \| 0 \| 10 \| imm4 \| 11100 \| 0 \| pattern \| Rd

Description

Determines the number of active elements implied by the named predicate constraint, multiplies that by an immediate in the range 1 to 16 inclusive, and then places the result in the scalar destination. The named predicate constraint limits the number of active elements in a single predicate to: Unspecified or out of range constraint encodings generate an empty predicate or zero element count rather than Undefined Instruction exception.

Operation

CheckSVEEnabled();
integer count = DecodePredCount(pat, esize);

X[d, 64] = (count * imm)<63:0>;