SQSUBR

Signed saturating subtraction reversed vectors (predicated).

Subtract active signed elements of the first source vector from corresponding signed elements of the second source vector and destructively place the results in the corresponding elements of the first source vector. Each result element is saturated to the N-bit element's signed integer range -2(N-1) to (2(N-1) )-1. Inactive elements in the destination vector register remain unmodified.

313029282726252423222120191817161514131211109876543210
01000100size011110100PgZmZdn

SVE2

SQSUBR <Zdn>.<T>, <Pg>/M, <Zdn>.<T>, <Zm>.<T>

if !HaveSVE2() then UNDEFINED; integer esize = 8 << UInt(size); integer g = UInt(Pg); integer dn = UInt(Zdn); integer m = UInt(Zm); boolean unsigned = FALSE;

Assembler Symbols

<Zdn>

Is the name of the first source and destination scalable vector register, encoded in the "Zdn" field.

<T> Is the size specifier, encoded in size:
size <T>
00 B
01 H
10 S
11 D
<Pg>

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

<Zm>

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

Operation

CheckSVEEnabled(); integer elements = VL DIV esize; bits(PL) mask = P[g]; bits(VL) operand1 = Z[dn]; bits(VL) operand2 = Z[m]; bits(VL) result; for e = 0 to elements-1 integer element1 = SInt(Elem[operand1, e, esize]); integer element2 = SInt(Elem[operand2, e, esize]); if ElemP[mask, e, esize] == '1' then integer res = SInt(Sat(element2 - element1, esize, unsigned)); Elem[result, e, esize] = res<esize-1:0>; else Elem[result, e, esize] = Elem[operand1, e, esize]; Z[dn] = result;

Operational information

If PSTATE.DIT is 1:

This instruction might be immediately preceded in program order by a MOVPRFX instruction that conforms to all of the following requirements, otherwise the behavior of either or both instructions is unpredictable:

The MOVPRFX instructions that can be used with this instruction are as follows:


Internal version only: isa v30.44, AdvSIMD v27.08, pseudocode v8.5-2019-06_rc2-5-g22901f2, sve v2019-06_rc4 ; Build timestamp: 2019-06-26T22:04

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