SDOT (2-way, multiple and indexed vector)

Multi-vector signed integer dot-product by indexed element

The signed integer dot product instruction computes the dot product of two signed 16-bit integer values held in each 32-bit element of the two or four first source vectors and two signed 16-bit integer values in the corresponding indexed 32-bit element of the second source vector. The widened dot product result is destructively added to the corresponding 32-bit element of the ZA single-vector groups.

The groups within the second source vector are specified using an immediate element index which selects the same group position within each 128-bit vector segment. The index range is from 0 to 3, encoded in 2 bits.

The single-vector group within each half of or each quarter of the ZA array is selected by the sum of the vector select register and offset , modulo half or quarter the number of ZA array vectors.

The vector group symbol, VGx2 or VGx4, indicates that the ZA operand consists of two or four ZA single-vector groups respectively. The vector group symbol is preferred for disassembly, but optional in assembler source code.

This instruction is unpredicated.

It has encodings from 2 classes: Two ZA single-vectors and Four ZA single-vectors

Two ZA single-vectors
(FEAT_SME2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF); constant integer v = UInt('010':Rv); constant integer esize = 32; constant integer n = UInt(Zn:'0'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off3); constant integer index = UInt(i2); constant integer nreg = 2;

Four ZA single-vectors
(FEAT_SME2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF); constant integer v = UInt('010':Rv); constant integer esize = 32; constant integer n = UInt(Zn:'00'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off3); constant integer index = UInt(i2); constant integer nreg = 4;