Arm® A64 Instruction Set Architecture: Armv8, for Armv8-A architecture profile

PUNPKHI, PUNPKLO

Unpack and widen half of predicate.

Unpack elements from the lowest or highest half of the source predicate and place in elements of twice their size within the destination predicate. This instruction is unpredicated.

It has encodings from 2 classes: High half and Low half

High half

if !HaveSVE() then UNDEFINED;
integer esize = 16;
integer n = UInt(Pn);
integer d = UInt(Pd);
boolean hi = TRUE;

Low half

if !HaveSVE() then UNDEFINED;
integer esize = 16;
integer n = UInt(Pn);
integer d = UInt(Pd);
boolean hi = FALSE;

Assembler Symbols

CheckSVEEnabled();
integer elements = VL DIV esize;
bits(PL) operand = P[n];
bits(PL) result;

for e = 0 to elements-1
    ElemP[result, e, esize] = ElemP[operand, if hi then e + elements else e, esize DIV 2];

P[d] = result;