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FMLALT (vectors)

Half-precision floating-point multiply-add long to single-precision (top).

This half-precision floating-point multiply-add long instruction widens the odd-numbered 16-bit half-precision elements in the first source vector and the corresponding elements in the second source vector to single-precision format and then destructively multiplies and adds these values without intermediate rounding to the overlapping 32-bit single-precision elements of the addend and destination vector. This instruction is unpredicated.

313029282726252423222120191817161514131211109876543210
01100100101Zm100001ZnZda

SVE2

FMLALT <Zda>.S, <Zn>.H, <Zm>.H

if !HaveSVE2() then UNDEFINED;
integer esize = 32;
integer n = UInt(Zn);
integer m = UInt(Zm);
integer da = UInt(Zda);
boolean op1_neg = FALSE;

Assembler Symbols

<Zda>

Is the name of the third source and destination scalable vector register, encoded in the "Zda" 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 elements = VL DIV esize;
bits(VL) operand1 = Z[n];
bits(VL) operand2 = Z[m];
bits(VL) operand3 = Z[da];
bits(VL) result;

for e = 0 to elements-1
    bits(esize DIV 2) element1 = Elem[operand1, 2 * e + 1, esize DIV 2];
    bits(esize DIV 2) element2 = Elem[operand2, 2 * e + 1, esize DIV 2];
    bits(esize) element3 = Elem[operand3, e, esize];
    if op1_neg then element1 = FPNeg(element1);
    Elem[result, e, esize] = FPMulAddH(element3, element1, element2, FPCR);

Z[da] = result;

Operational information

This instruction might be immediately preceded in program order by a MOVPRFX instruction that conforms to all of the following requirements, otherwise the behavior of either or both instructions is unpredictable:

  • The MOVPRFX instruction must specify the same destination register as this instruction.
  • The destination register must not refer to architectural register state referenced by any other source operand register of this instruction.
The MOVPRFX instructions that can be used with this instruction are as follows:
  • An unpredicated MOVPRFX instruction.