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HISTSEG

Count matching elements in vector segments.

This instruction compares each 8-bit byte element of the first source vector with all of the elements in the corresponding 128-bit segment of the second source vector and places the count of matching elements in the corresponding element of the destination vector. This instruction is unpredicated.

313029282726252423222120191817161514131211109876543210
01000101size1Zm101000ZnZd

HISTSEG <Zd>.B, <Zn>.B, <Zm>.B

if !HaveSVE2() then UNDEFINED;
if size != '00' then UNDEFINED;
integer esize = 8;
integer d = UInt(Zd);
integer n = UInt(Zn);
integer m = UInt(Zm);

Assembler Symbols

<Zd>

Is the name of the destination scalable vector register, encoded in the "Zd" field.

<Zn>

Is the name of the first source scalable vector register, encoded in the "Zn" field.

<Zm>

Is the name of the second source scalable vector register, encoded in the "Zm" field.

Operation

CheckSVEEnabled();
integer segments = VL DIV 128;
integer eltspersegment = 128 DIV esize;
bits(VL) operand1 = Z[n];
bits(VL) operand2 = Z[m];
bits(VL) result;

for b = 0 to segments-1
    for s = 0 to eltspersegment-1
        integer count = 0;
        integer e = eltspersegment * b + s;
        bits(esize) element1 = Elem[operand1, e, esize];
        for i = 0 to eltspersegment-1
            integer e2 = eltspersegment * b + i;
            bits(esize) element2 = Elem[operand2, e2, esize];
            if element1 == element2 then
                count = count + 1;
        Elem[result, e, esize] = count<esize-1:0>;

Z[d] = result;