vsli

Vector Shift Left and Insert

VSLI<c>.<size> <Qd>, <Qm>, #<imm>

Shifts bits left and inserts into destination (merging).

Pseudocode Operation

for i = 0 to elements_in_Qd - 1
  shift_amount ← imm6
  shifted ← Qm[i] << shift_amount
  mask ← (1 << shift_amount) - 1
  Qd[i] ← (Qd[i] & ~mask) | (shifted & mask)
endfor

Example

VSLI.size q0, q2, #16

Encoding

Binary Layout

1111001

31:25

1

24

1

23

D

22

imm6

21:16

Vd

15:12

0101

11:8

L

7

1

6

M

5

1

4

Vm

3:0

 

Format NEON Shift

Opcode 0xF3800550

Extension NEON (SIMD)

Operands

• Qd
  Destination 128-bit SIMD register
• Qm
  Second source 128-bit SIMD register
• imm
  Signed immediate value

Related

More in NEON (SIMD)

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xF3800510	VSLI{<c>}{<q>}.<size> {<Dd>,} <Dm>, #<imm>		A32		1111001 | 1 | 1 | D | imm6 | Vd | 0101 | L | 0 | M | 1 | Vm
0xF3800550	VSLI{<c>}{<q>}.<size> {<Qd>,} <Qm>, #<imm>		A32		1111001 | 1 | 1 | D | imm6 | Vd | 0101 | L | 1 | M | 1 | Vm
0xFF800510	VSLI{<c>}{<q>}.<size> {<Dd>,} <Dm>, #<imm>		T32		111 | 1 | 11111 | D | imm6 | Vd | 0101 | L | 0 | M | 1 | Vm
0xFF800550	VSLI{<c>}{<q>}.<size> {<Qd>,} <Qm>, #<imm>		T32		111 | 1 | 11111 | D | imm6 | Vd | 0101 | L | 1 | M | 1 | Vm

Description

Vector Shift Left and Insert takes each element in the operand vector, left shifts them by an immediate value, and inserts 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. There is no distinction between data types. 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.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();  CheckAdvSIMDEnabled();
    mask = LSL(Ones(esize), shift_amount);
    for r = 0 to regs-1
        for e = 0 to elements-1
            shifted_op = LSL(Elem[D[m+r],e,esize], shift_amount);
            Elem[D[d+r],e,esize] = (Elem[D[d+r],e,esize] AND NOT(mask)) OR shifted_op;