subhnb

Subtract High Narrow (Bottom) (SVE2)

SUBHNB <Zd>.<T>, <Zn>.<Tb>, <Zm>.<Tb>

Subtracts wide elements, narrows, and stores in bottom half.

Pseudocode Operation

No pseudocode available.

Encoding

Binary Layout

01000101

31:24

size

23:22

20:16

011

15:13

9:5

4:0

Format SVE2 Math

Opcode 0x45207000

Extension SVE2

Operands

Zd
Dest
Zn
Src 1
Zm
Src 2

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x45207000	SUBHNB <Zd>.<T>, <Zn>.<Tb>, <Zm>.<Tb>		A64		01000101 \| size \| 1 \| Zm \| 011 \| 1 \| 0 \| 0 \| Zn \| Zd

Description

Subtract each vector element of the second source vector from the corresponding vector element in the first source vector, and place the most significant half of the result in the even-numbered half-width destination elements, while setting the odd-numbered elements to zero. This instruction is unpredicated.

Operation

CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer elements = VL DIV esize;
bits(VL) operand1 = Z[n, VL];
bits(VL) operand2 = Z[m, VL];
bits(VL) result;
constant integer halfesize = esize DIV 2;

for e = 0 to elements-1
    integer element1 = UInt(Elem[operand1, e, esize]);
    integer element2 = UInt(Elem[operand2, e, esize]);
    integer res = (element1 - element2) >> halfesize;
    Elem[result, 2*e + 0, halfesize] = res<halfesize-1:0>;
    Elem[result, 2*e + 1, halfesize] = Zeros(halfesize);

Z[d, VL] = result;