FNMAD
Floating-point negated fused multiply-add vectors (predicated), writing multiplicand [Zdn = -Za + -Zdn * Zm]
Multiply the corresponding active floating-point elements of the first and second source vectors and add to elements of the third (addend) vector without intermediate rounding. Destructively place the negated results in the destination and first source (multiplicand) vector. Inactive elements in the destination vector register remain unmodified.
Green
True
True
True
0
1
1
0
0
1
0
1
1
1
1
0
FNMAD <Zdn>.<T>, <Pg>/M, <Zm>.<T>, <Za>.<T>
if !HaveSVE() && !HaveSME() then UNDEFINED;
if size == '00' then UNDEFINED;
constant integer esize = 8 << UInt(size);
integer g = UInt(Pg);
integer dn = UInt(Zdn);
integer m = UInt(Zm);
integer a = UInt(Za);
boolean op1_neg = TRUE;
boolean op3_neg = TRUE;
<Zdn>
Is the name of the first source and destination scalable vector register, encoded in the "Zdn" field.
<T>
Is the size specifier,
size
<T>
00
RESERVED
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.
CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
bits(PL) mask = P[g, PL];
bits(VL) operand1 = Z[dn, VL];
bits(VL) operand2 = if AnyActiveElement(mask, esize) then Z[m, VL] else Zeros(VL);
bits(VL) operand3 = if AnyActiveElement(mask, esize) then Z[a, VL] else Zeros(VL);
bits(VL) result;
for e = 0 to elements-1
if ActivePredicateElement(mask, e, esize) then
bits(esize) element1 = Elem[operand1, e, esize];
bits(esize) element2 = Elem[operand2, e, esize];
bits(esize) element3 = Elem[operand3, e, esize];
if op1_neg then element1 = FPNeg(element1);
if op3_neg then element3 = FPNeg(element3);
Elem[result, e, esize] = FPMulAdd(element3, element1, element2, FPCR[]);
else
Elem[result, e, esize] = Elem[operand1, e, esize];
Z[dn, VL] = result;