You copied the Doc URL to your clipboard.

SQSHL (immediate)

Signed saturating Shift Left (immediate). This instruction reads each vector element in the source SIMD&FP register, shifts each result by an immediate value, places the final result in a vector, and writes the vector to the destination SIMD&FP register. The results are truncated. For rounded results, see UQRSHL.

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

Scalar

313029282726252423222120191817161514131211109876543210
010111110!= 0000immb011101RnRd
Uimmhop

Scalar

SQSHL <V><d>, <V><n>, #<shift>

integer d = UInt(Rd);
integer n = UInt(Rn);

if immh == '0000' then UNDEFINED;
integer esize = 8 << HighestSetBit(immh);
integer datasize = esize;
integer elements = 1;

integer shift = UInt(immh:immb) - esize;

boolean src_unsigned;
boolean dst_unsigned;
case op:U of
    when '00' UNDEFINED;
    when '01' src_unsigned = FALSE; dst_unsigned = TRUE;
    when '10' src_unsigned = FALSE; dst_unsigned = FALSE;
    when '11' src_unsigned = TRUE; dst_unsigned = TRUE;

Vector

313029282726252423222120191817161514131211109876543210
0Q0011110!= 0000immb011101RnRd
Uimmhop

Vector

SQSHL <Vd>.<T>, <Vn>.<T>, #<shift>

integer d = UInt(Rd);
integer n = UInt(Rn);

if immh == '0000' then SEE(asimdimm);
if immh<3>:Q == '10' then UNDEFINED;
integer esize = 8 << HighestSetBit(immh);
integer datasize = if Q == '1' then 128 else 64;
integer elements = datasize DIV esize;

integer shift = UInt(immh:immb) - esize;

boolean src_unsigned;
boolean dst_unsigned;
case op:U of
    when '00' UNDEFINED;
    when '01' src_unsigned = FALSE; dst_unsigned = TRUE;
    when '10' src_unsigned = FALSE; dst_unsigned = FALSE;
    when '11' src_unsigned = TRUE; dst_unsigned = TRUE;

Assembler Symbols

<V> Is a width specifier, encoded in immh:
immh <V>
0000 RESERVED
0001 B
001x H
01xx S
1xxx D
<d>

Is the number of the SIMD&FP destination register, in the "Rd" field.

<n>

Is the number of the first SIMD&FP source register, encoded in the "Rn" field.

<Vd>

Is the name of the SIMD&FP destination register, encoded in the "Rd" field.

<T> Is an arrangement specifier, encoded in immh:Q:
immh Q <T>
0000 x SEE Advanced SIMD modified immediate
0001 0 8B
0001 1 16B
001x 0 4H
001x 1 8H
01xx 0 2S
01xx 1 4S
1xxx 0 RESERVED
1xxx 1 2D
<Vn>

Is the name of the SIMD&FP source register, encoded in the "Rn" field.

<shift> For the scalar variant: is the left shift amount, in the range 0 to the operand width in bits minus 1, encoded in immh:immb:
immh <shift>
0000 RESERVED
0001 (UInt(immh:immb)-8)
001x (UInt(immh:immb)-16)
01xx (UInt(immh:immb)-32)
1xxx (UInt(immh:immb)-64)
For the vector variant: is the left shift amount, in the range 0 to the element width in bits minus 1, encoded in immh:immb:
immh <shift>
0000 SEE Advanced SIMD modified immediate
0001 (UInt(immh:immb)-8)
001x (UInt(immh:immb)-16)
01xx (UInt(immh:immb)-32)
1xxx (UInt(immh:immb)-64)

Operation

CheckFPAdvSIMDEnabled64();
bits(datasize) operand = V[n];
bits(datasize) result;
integer element;
boolean sat;

for e = 0 to elements-1
    element = Int(Elem[operand, e, esize], src_unsigned) << shift;
    (Elem[result, e, esize], sat) = SatQ(element, esize, dst_unsigned);
    if sat then FPSR.QC = '1';

V[d] = result;
Was this page helpful? Yes No