FMLAL (multiple and indexed vector, FP8 to FP16)

Multi-vector 8-bit floating-point multiply-add long by indexed element to half-precision

This 8-bit floating-point multiply-add long instruction widens all 8-bit floating-point elements in the one, two, or four first source vectors and the indexed element of the second source vector to half-precision format and multiplies the corresponding elements. The intermediate products are scaled by 2^{-UInt(FPMR.LSCALE[3:0])} before being destructively added without intermediate rounding to the overlapping 16-bit half-precision elements of the ZA double-vector groups.

The 8-bit floating-point elements within the second source vector are specified using a 4-bit immediate index which selects the same element position within each 128-bit vector segment.

The double-vector group within all of, each half of, or each quarter of the ZA array is selected by the sum of the vector select register and offset range, modulo all, 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 double-vector groups respectively. The vector group symbol is preferred for disassembly, but optional in assembler source code.

The 8-bit floating-point encoding format for the elements of the first source vector and the second source vector is selected by FPMR.F8S1 and FPMR.F8S2 respectively.

This instruction is unpredicated.

It has encodings from 3 classes: One ZA double-vector , Two ZA double-vectors and Four ZA double-vectors

One ZA double-vector
(FEAT_SME_F8F16)

if !IsFeatureImplemented(FEAT_SME_F8F16) then UNDEFINED; constant integer v = UInt('010':Rv); constant integer n = UInt(Zn); constant integer m = UInt('0':Zm); constant integer offset = UInt(off3:'0'); constant integer index = UInt(i4A:i4B:i4C); constant integer nreg = 1;

Two ZA double-vectors
(FEAT_SME_F8F16)

if !IsFeatureImplemented(FEAT_SME_F8F16) then UNDEFINED; constant integer v = UInt('010':Rv); constant integer n = UInt(Zn:'0'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off2:'0'); constant integer index = UInt(i4h:i4l); constant integer nreg = 2;

Four ZA double-vectors
(FEAT_SME_F8F16)

if !IsFeatureImplemented(FEAT_SME_F8F16) then UNDEFINED; constant integer v = UInt('010':Rv); constant integer n = UInt(Zn:'00'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off2:'0'); constant integer index = UInt(i4h:i4l); constant integer nreg = 4;