You copied the Doc URL to your clipboard.

RSHRNT

Rounding shift right narrow by immediate (top).

Shift each unsigned integer value in the source vector elements right by an immediate value, and place the rounded results in the odd-numbered half-width destination elements, leaving the even-numbered elements unchanged. The immediate shift amount is an unsigned value in the range 1 to number of bits per element. This instruction is unpredicated.

313029282726252423222120191817161514131211109876543210
010001010tszh1tszlimm3000111ZnZd
URT

RSHRNT <Zd>.<T>, <Zn>.<Tb>, #<const>

if !HaveSVE2() then UNDEFINED;
bits(3) tsize = tszh:tszl;
case tsize of
    when '000' UNDEFINED;
    when '001' esize = 8;
    when '01x' esize = 16;
    when '1xx' esize = 32;
integer n = UInt(Zn);
integer d = UInt(Zd);
integer shift = (2 * esize) - UInt(tsize:imm3);

Assembler Symbols

<Zd>

Is the name of the destination scalable vector register, encoded in the "Zd" field.

<T> Is the size specifier, encoded in tszh:tszl:
tszh tszl <T>
0 00 RESERVED
0 01 B
0 1x H
1 xx S
<Zn>

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

<Tb> Is the size specifier, encoded in tszh:tszl:
tszh tszl <Tb>
0 00 RESERVED
0 01 H
0 1x S
1 xx D
<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 (2 * esize);
bits(VL) operand = Z[n];
bits(VL) result = Z[d];
integer round_const = 1 << (shift-1);

for e = 0 to elements-1
    bits(2*esize) element = Elem[operand, e, 2*esize];
    integer res = (UInt(element) + round_const) >> shift;
    Elem[result, 2*e + 1, esize] = res<esize-1:0>;

Z[d] = result;

Operational information

If PSTATE.DIT is 1:

  • The execution time of this instruction is independent of:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.
  • The response of this instruction to asynchronous exceptions does not vary based on:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.
Previous Next