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SQDMULH (vectors)

Signed saturating doubling multiply high (unpredicated).

Multiply then double the corresponding signed elements of the first and second source vectors, and place the most significant half of the results in the corresponding elements of the destination vector register. Each result element is saturated to the N-bit element's signed integer range -2(N-1) to (2(N-1) )-1. This instruction is unpredicated.

313029282726252423222120191817161514131211109876543210
00000100size1Zm011100ZnZd

SVE2

SQDMULH <Zd>.<T>, <Zn>.<T>, <Zm>.<T>

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

Assembler Symbols

<Zd>

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

<T> Is the size specifier, encoded in size:
size <T>
00 B
01 H
10 S
11 D
<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 elements = VL DIV esize;
bits(VL) operand1 = Z[n];
bits(VL) operand2 = Z[m];
bits(VL) result;

for e = 0 to elements-1
    integer element1 = SInt(Elem[operand1, e, esize]);
    integer element2 = SInt(Elem[operand2, e, esize]);
    integer res = 2 * element1 * element2;
    Elem[result, e, esize] = SignedSat(res >> esize, esize);

Z[d] = result;

Operational information

If PSTATE.DIT is 1:

  • The execution time of this instruction is independent of:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.
  • The response of this instruction to asynchronous exceptions does not vary based on:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.
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