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MSB

Multiply-subtract vectors (predicated), writing multiplicand [Zdn = Za - Zdn * Zm].

Multiply the corresponding active elements of the first and second source vectors and subtract from elements of the third (addend) vector. Destructively place the results in the destination and first source (multiplicand) vector. Inactive elements in the destination vector register remain unmodified.

313029282726252423222120191817161514131211109876543210
00000100size0Zm111PgZaZdn

SVE

MSB <Zdn>.<T>, <Pg>/M, <Zm>.<T>, <Za>.<T>

if !HaveSVE() then UNDEFINED;
integer esize = 8 << UInt(size);
integer g = UInt(Pg);
integer dn = UInt(Zdn);
integer m = UInt(Zm);
integer a = UInt(Za);
boolean sub_op = TRUE;

Assembler Symbols

<Zdn>

Is the name of the first source and destination scalable vector register, encoded in the "Zdn" field.

<T> Is the size specifier, encoded in size:
size <T>
00 B
01 H
10 S
11 D
<Pg>

Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.

<Zm>

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

<Za>

Is the name of the third source scalable vector register, encoded in the "Za" field.

Operation

CheckSVEEnabled();
integer elements = VL DIV esize;
bits(PL) mask = P[g];
bits(VL) operand1 = Z[dn];
bits(VL) operand2 = Z[m];
bits(VL) operand3 = Z[a];
bits(VL) result;

for e = 0 to elements-1
    integer element1 = UInt(Elem[operand1, e, esize]);
    integer element2 = UInt(Elem[operand2, e, esize]);
    if ElemP[mask, e, esize] == '1' then
        integer product = element1 * element2;
        if sub_op then
            Elem[result, e, esize] = Elem[operand3, e, esize] - product;
        else
            Elem[result, e, esize] = Elem[operand3, e, esize] + product;
    else
        Elem[result, e, esize] = Elem[operand1, e, esize];

Z[dn] = result;
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