SQRDMLSH (indexed)

Signed saturating rounding doubling multiply-subtract high by indexed element

This instruction multiplies all signed elements within each 128-bit segment of the first source vector by the specified signed element of the corresponding second source vector segment, and then doubles the result and destructively subtracts the rounded high half of each result to the corresponding elements of the addend and destination vector. Each destination element is saturated to the N-bit element's signed integer range -2^(N-1) to (2^(N-1))-1.

The elements within the second source vector are specified using an immediate index that selects the same element position within each 128-bit vector segment. The index range is from 0 to one less than the number of elements per 128-bit segment.

It has encodings from 3 classes: 16-bit , 32-bit and 64-bit

16-bit
(FEAT_SVE2 || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 16; let index : integer = UInt(i3h::i3l); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let da : integer = UInt(Zda);

32-bit
(FEAT_SVE2 || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 32; let index : integer = UInt(i2); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let da : integer = UInt(Zda);

64-bit
(FEAT_SVE2 || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 64; let index : integer = UInt(i1); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let da : integer = UInt(Zda);