USDOT (multiple and indexed vector)

Multi-vector unsigned by signed integer dot-product by indexed element

The unsigned by signed integer dot product instruction computes the dot product of four unsigned 8-bit integer values held in each 32-bit element of the two or four first source vectors and four signed 8-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 vector numbers forming the single-vector group within each half of or each quarter of the ZA array are selected by the sum of the vector select register and immediate 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)

if !HaveSME2() then UNDEFINED; integer v = UInt('010':Rv); constant integer esize = 32; integer n = UInt(Zn:'0'); integer m = UInt('0':Zm); integer offset = UInt(off3); integer index = UInt(i2); constant integer nreg = 2;

Four ZA single-vectors
(FEAT_SME2)

if !HaveSME2() then UNDEFINED; integer v = UInt('010':Rv); constant integer esize = 32; integer n = UInt(Zn:'00'); integer m = UInt('0':Zm); integer offset = UInt(off3); integer index = UInt(i2); constant integer nreg = 4;