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URSHR

Unsigned rounding shift right by immediate.

Shift right by immediate each active unsigned element of the source vector, and destructively place the rounded results in the corresponding elements of the source vector. The immediate shift amount is an unsigned value in the range 1 to number of bits per element. Inactive elements in the destination vector register remain unmodified.

313029282726252423222120191817161514131211109876543210
00000100tszh001101100Pgtszlimm3Zdn
LU
if !HaveSVE2() then UNDEFINED;
bits(4) tsize = tszh:tszl;
case tsize of
    when '0000' UNDEFINED;
    when '0001' esize = 8;
    when '001x' esize = 16;
    when '01xx' esize = 32;
    when '1xxx' esize = 64;
integer g = UInt(Pg);
integer dn = UInt(Zdn);
integer shift = (2 * esize) - UInt(tsize:imm3);

Assembler Symbols

<Zdn>

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

<T> Is the size specifier, encoded in tszh:tszl:
tszh tszl <T>
00 00 RESERVED
00 01 B
00 1x H
01 xx S
1x xx D
<Pg>

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

<const>

Is the immediate shift amount, in the range 1 to number of bits per element, encoded in "tsz:imm3".

Operation

CheckSVEEnabled();
integer elements = VL DIV esize;
bits(VL) operand1 = Z[dn];
bits(PL) mask = P[g];
bits(VL) result;
integer round_const = 1 << (shift-1);

for e = 0 to elements-1
    integer element1 = UInt(Elem[operand1, e, esize]);
    if ElemP[mask, e, esize] == '1' then
        integer res = (element1 + round_const) >> shift;
        Elem[result, e, esize] = res<esize-1:0>;
    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.