UDOT (4-way, indexed) Unsigned integer indexed dot product The unsigned integer indexed dot product instruction computes the dot product of a group of four unsigned 8-bit or 16-bit integer values held in each 32-bit or 64-bit element of the first source vector multiplied by a group of four unsigned 8-bit or 16-bit integer values in an indexed 32-bit or 64-bit element of the second source vector, and then destructively adds the widened dot product to the corresponding 32-bit or 64-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 one less than the number of groups per 128-bit segment, encoded in 1 to 2 bits depending on the size of the group. This instruction is unpredicated. Green False True True It has encodings from 2 classes: 32-bit and 64-bit 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 0 1 UDOT <Zda>.S, <Zn>.B, <Zm>.B[<imm>] if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) 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); 0 1 0 0 0 1 0 0 1 1 1 0 0 0 0 0 1 UDOT <Zda>.D, <Zn>.H, <Zm>.H[<imm>] if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 64; constant integer index = UInt(i1); 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> For the 32-bit variant: is the name of the second source scalable vector register Z0-Z7, encoded in the "Zm" field. <Zm> For the 64-bit variant: is the name of the second source scalable vector register Z0-Z15, encoded in the "Zm" field. <imm> For the 32-bit variant: is the immediate index of a 32-bit group of four 8-bit values within each 128-bit vector segment, in the range 0 to 3, encoded in the "i2" field. <imm> For the 64-bit variant: is the immediate index of a 64-bit group of four 16-bit values within each 128-bit vector segment, in the range 0 to 1, encoded in the "i1" 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 3 constant integer element1 = UInt(Elem[operand1, 4 * e + i, esize DIV 4]); constant integer element2 = UInt(Elem[operand2, 4 * s + i, esize DIV 4]); res = res + element1 * element2; Elem[result, e, esize] = res; Z[da, VL] = result;