SDOT (2-way, indexed)
Signed integer indexed dot product
The signed integer indexed dot product instruction computes the dot product of a group of two signed 16-bit integer values held in each 32-bit element of the first source vector multiplied by a group of two signed 16-bit integer values in an indexed 32-bit element of the second source vector, and then destructively adds the widened dot product to the corresponding 32-bit element of the destination vector.
The groups within the second source vector are specified using an immediate index which selects the same group position within each 128-bit vector segment. The index range is from 0 to 3. This instruction is unpredicated.
Green
False
True
True
0
1
0
0
0
1
0
0
1
0
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1
1
0
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1
0
SDOT <Zda>.S, <Zn>.H, <Zm>.H[<imm>]
if !IsFeatureImplemented(FEAT_SME2) && !IsFeatureImplemented(FEAT_SVE2p1) then UNDEFINED;
constant integer esize = 32;
constant integer index = UInt(i2);
constant integer n = UInt(Zn);
constant integer m = UInt(Zm);
constant integer da = UInt(Zda);
<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 Z0-Z7, encoded in the "Zm" field.
<imm>
Is the immediate index of a group of two 16-bit elements within each 128-bit vector segment, in the range 0 to 3, encoded in the "i2" field.
CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
constant integer eltspersegment = 128 DIV esize;
constant bits(VL) operand1 = Z[n, VL];
constant bits(VL) operand2 = Z[m, VL];
constant bits(VL) operand3 = Z[da, VL];
bits(VL) result;
for e = 0 to elements-1
constant integer segmentbase = e - (e MOD eltspersegment);
constant integer s = segmentbase + index;
bits(esize) res = Elem[operand3, e, esize];
for i = 0 to 1
constant integer element1 = SInt(Elem[operand1, 2 * e + i, esize DIV 2]);
constant integer element2 = SInt(Elem[operand2, 2 * s + i, esize DIV 2]);
res = res + element1 * element2;
Elem[result, e, esize] = res;
Z[da, VL] = result;