SQDMLSLB (indexed)

Signed saturating doubling multiply-subtract long from accumulator (bottom, indexed)

Multiply then double the even-numbered signed elements within each 128-bit segment of the first source vector and the specified signed element in the corresponding second source vector segment. Each intermediate value is saturated to the double-width N-bit value's signed integer range -2^(N-1) to (2^(N-1) )-1. Then destructively subtract from the overlapping double-width elements of the addend and destination vector. Each destination element is saturated to the double-width 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 which 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, encoded in 2 or 3 bits depending on the size of the element.

It has encodings from 2 classes: 32-bit and 64-bit

32-bit

if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 16; constant integer index = UInt(i3h:i3l); constant integer n = UInt(Zn); constant integer m = UInt(Zm); constant integer da = UInt(Zda); constant integer sel = 0;

64-bit

if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 32; constant integer index = UInt(i2h:i2l); constant integer n = UInt(Zn); constant integer m = UInt(Zm); constant integer da = UInt(Zda); constant integer sel = 0;