You copied the Doc URL to your clipboard.

VSHL (immediate)

Vector Shift Left (immediate) takes each element in a vector of integers, left shifts them by an immediate value, and places the results in the destination vector.

Bits shifted out of the left of each element are lost.

The elements must all be the same size, and can be 8-bit, 16-bit, 32-bit, or 64-bit integers. There is no distinction between signed and unsigned integers.

Depending on settings in the CPACR, NSACR, and HCPTR registers, and the Security state and PE mode in which the instruction is executed, an attempt to execute the instruction might be undefined, or trapped to Hyp mode. For more information see Enabling Advanced SIMD and floating-point support.

It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .

A1

313029282726252423222120191817161514131211109876543210
111100101Dimm6Vd0101LQM1Vm

64-bit SIMD vector (!(imm6 == 000xxx && L == 0) && Q == 0)

VSHL{<c>}{<q>}.I<size> {<Dd>,} <Dm>, #<imm>

128-bit SIMD vector (!(imm6 == 000xxx && L == 0) && Q == 1)

VSHL{<c>}{<q>}.I<size> {<Qd>,} <Qm>, #<imm>

if L:imm6 == '0000xxx' then SEE "Related encodings";
if Q == '1' && (Vd<0> == '1' || Vm<0> == '1') then UNDEFINED;
case L:imm6 of
    when '0001xxx'  esize = 8;  elements = 8;  shift_amount = UInt(imm6) - 8;
    when '001xxxx'  esize = 16;  elements = 4;  shift_amount = UInt(imm6) - 16;
    when '01xxxxx'  esize = 32;  elements = 2;  shift_amount = UInt(imm6) - 32;
    when '1xxxxxx'  esize = 64;  elements = 1;  shift_amount = UInt(imm6);
d = UInt(D:Vd);  m = UInt(M:Vm);  regs = if Q == '0' then 1 else 2;

T1

15141312111098765432101514131211109876543210
111011111Dimm6Vd0101LQM1Vm

64-bit SIMD vector (!(imm6 == 000xxx && L == 0) && Q == 0)

VSHL{<c>}{<q>}.I<size> {<Dd>,} <Dm>, #<imm>

128-bit SIMD vector (!(imm6 == 000xxx && L == 0) && Q == 1)

VSHL{<c>}{<q>}.I<size> {<Qd>,} <Qm>, #<imm>

if L:imm6 == '0000xxx' then SEE "Related encodings";
if Q == '1' && (Vd<0> == '1' || Vm<0> == '1') then UNDEFINED;
case L:imm6 of
    when '0001xxx'  esize = 8;  elements = 8;  shift_amount = UInt(imm6) - 8;
    when '001xxxx'  esize = 16;  elements = 4;  shift_amount = UInt(imm6) - 16;
    when '01xxxxx'  esize = 32;  elements = 2;  shift_amount = UInt(imm6) - 32;
    when '1xxxxxx'  esize = 64;  elements = 1;  shift_amount = UInt(imm6);
d = UInt(D:Vd);  m = UInt(M:Vm);  regs = if Q == '0' then 1 else 2;

Related encodings: See Advanced SIMD one register and modified immediate for the T32 instruction set, or Advanced SIMD one register and modified immediate for the A32 instruction set.

Assembler Symbols

<c>

For encoding A1: see Standard assembler syntax fields. This encoding must be unconditional.

For encoding T1: see Standard assembler syntax fields.

<q>

See Standard assembler syntax fields.

<size> Is the data size for the elements of the vectors, encoded in L:imm6<5:3>:
L imm6<5:3> <size>
0 001 8
0 01x 16
0 1xx 32
1 xxx 64
<Qd>

Is the 128-bit name of the SIMD&FP destination register, encoded in the "D:Vd" field as <Qd>*2.

<Qm>

Is the 128-bit name of the SIMD&FP source register, encoded in the "M:Vm" field as <Qm>*2.

<Dd>

Is the 64-bit name of the SIMD&FP destination register, encoded in the "D:Vd" field.

<Dm>

Is the 64-bit name of the SIMD&FP source register, encoded in the "M:Vm" field.

<imm>

Is an immediate value, in the range 0 to <size>-1, encoded in the "imm6" field.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();  CheckAdvSIMDEnabled();
    for r = 0 to regs-1
        for e = 0 to elements-1
            Elem[D[d+r],e,esize] = LSL(Elem[D[m+r],e,esize], shift_amount);

Operational information

If CPSR.DIT is 1 and this instruction passes its condition execution check:

  • 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.