LASTB (SIMD&FP scalar)

Extract last element to SIMD&FP scalar register

If there is an active element then extract the last active element from the final source vector register. If there are no active elements, extract the highest-numbered element. Then place the extracted element in the destination SIMD&FP register.

313029282726252423222120191817161514131211109876543210
00000101size100011100PgZnVd
B

LASTB <V><d>, <Pg>, <Zn>.<T>

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 8 << UInt(size); constant integer g = UInt(Pg); constant integer n = UInt(Zn); constant integer d = UInt(Vd); constant boolean isBefore = TRUE;

Assembler Symbols

<V>

Is a width specifier, encoded in size:

size <V>
00 B
01 H
10 S
11 D
<d>

Is the number [0-31] of the destination SIMD&FP register, encoded in the "Vd" field.

<Pg>

Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.

<Zn>

Is the name of the source scalable vector register, encoded in the "Zn" field.

<T>

Is the size specifier, encoded in size:

size <T>
00 B
01 H
10 S
11 D

Operation

CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; constant bits(PL) mask = P[g, PL]; constant bits(VL) operand = Z[n, VL]; integer last = LastActiveElement(mask, esize); if isBefore then if last < 0 then last = elements - 1; else last = last + 1; if last >= elements then last = 0; V[d, esize] = Elem[operand, last, esize];


Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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