UQRSHRN, UQRSHRN2
Unsigned saturating rounded shift right narrow (immediate)
This instruction reads
each vector element in the
source SIMD&FP
register,
right shifts each result by an immediate value,
puts the final result into a vector,
and writes the vector to the lower or upper half of the
destination SIMD&FP register.
All the values in this instruction are unsigned integer values.
The results are rounded. For truncated results, see
UQSHRN.
The UQRSHRN instruction writes the vector
to the lower half of the
destination register and clears the upper half.
The UQRSHRN2 instruction writes the vector
to the upper half of the
destination register without affecting the other bits of the register.
If overflow occurs with any of the results, those results are saturated.
If saturation occurs, the cumulative saturation bit
FPSR.QC is set.
Depending on the settings in the CPACR_EL1,
CPTR_EL2, and CPTR_EL3 registers,
and the current Security state and Exception level,
an attempt to execute the instruction might be trapped.
It has encodings from 2 classes:
Scalar
and
Vector
0
1
1
1
1
1
1
1
0
!= 0000
1
0
0
1
1
1
UQRSHRN <Vb><d>, <Va><n>, #<shift>
if immh == '0000' then UNDEFINED;
if immh<3> == '1' then UNDEFINED;
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer esize = 8 << HighestSetBitNZ(immh<2:0>);
constant integer datasize = esize;
constant integer elements = 1;
constant integer part = 0;
constant integer shift = (2 * esize) - UInt(immh:immb);
constant boolean round = TRUE;
constant boolean unsigned = TRUE;
0
1
0
1
1
1
1
0
!= 0000
1
0
0
1
1
1
UQRSHRN{2} <Vd>.<Tb>, <Vn>.<Ta>, #<shift>
if immh == '0000' then SEE(asimdimm);
if immh<3> == '1' then UNDEFINED;
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer esize = 8 << HighestSetBitNZ(immh<2:0>);
constant integer datasize = 64;
constant integer part = UInt(Q);
constant integer elements = datasize DIV esize;
constant integer shift = (2 * esize) - UInt(immh:immb);
constant boolean round = TRUE;
constant boolean unsigned = TRUE;
<Vb>
Is the destination width specifier,
immh
<Vb>
0001
B
001x
H
01xx
S
1xxx
RESERVED
<d>
Is the number of the SIMD&FP destination register, in the "Rd" field.
<Va>
Is the source width specifier,
immh
<Va>
0001
H
001x
S
01xx
D
1xxx
RESERVED
<n>
Is the number of the first SIMD&FP source register, encoded in the "Rn" field.
<shift>
For the scalar variant: is the right shift amount, in the range 1 to the destination operand width in bits,
immh
<shift>
0001
16 - UInt(immh:immb)
001x
32 - UInt(immh:immb)
01xx
64 - UInt(immh:immb)
1xxx
RESERVED
<shift>
For the vector variant: is the right shift amount, in the range 1 to the destination element width in bits,
immh
<shift>
0001
16 - UInt(immh:immb)
001x
32 - UInt(immh:immb)
01xx
64 - UInt(immh:immb)
1xxx
RESERVED
2
Is the second and upper half specifier. If present it causes the operation to be performed on the upper 64 bits of the registers holding the narrower elements, and is
Q
2
0
[absent]
1
[present]
<Vd>
Is the name of the SIMD&FP destination register, encoded in the "Rd" field.
<Tb>
Is an arrangement specifier,
immh
Q
<Tb>
0001
0
8B
0001
1
16B
001x
0
4H
001x
1
8H
01xx
0
2S
01xx
1
4S
1xxx
x
RESERVED
<Vn>
Is the name of the SIMD&FP source register, encoded in the "Rn" field.
<Ta>
Is an arrangement specifier,
immh
<Ta>
0001
8H
001x
4S
01xx
2D
1xxx
RESERVED
CheckFPAdvSIMDEnabled64();
constant bits(datasize*2) operand = V[n, datasize*2];
bits(datasize) result;
integer element;
boolean sat;
for e = 0 to elements-1
element = RShr(Int(Elem[operand, e, 2*esize], unsigned), shift, round);
(Elem[result, e, esize], sat) = SatQ(element, esize, unsigned);
if sat then FPSR.QC = '1';
Vpart[d, part, datasize] = result;