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SQRSHL

Signed saturating rounding shift left by vector (predicated).

Shift active signed elements of the first source vector by corresponding elements of the second source vector and destructively place the rounded results in the corresponding elements of the first source vector. A positive shift amount performs a left shift, otherwise a right shift by the negated shift amount is performed. 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.

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01000100size001010100PgZmZdn
QRNU

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

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

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 element = SInt(Elem[operand1, e, esize]);
    integer shift = ShiftSat(SInt(Elem[operand2, e, esize]), esize);
    integer round_const = 1 << (-shift - 1); // 0 for left shift, 2^(n-1) for right shift
    if ElemP[mask, e, esize] == '1' then
        integer res = (element + round_const) << shift;
        Elem[result, e, esize] = SignedSat(res, esize);
    else
        Elem[result, e, esize] = Elem[operand1, e, esize];

Z[dn] = result;

Operational information

This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX instruction must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is unpredictable:

  • The MOVPRFX instruction must be unpredicated, or be predicated using the same governing predicate register and source element size as this instruction.
  • The MOVPRFX instruction must specify the same destination register as this instruction.
  • The destination register must not refer to architectural register state referenced by any other source operand register of this instruction.