LSL (immediate) -- A64

Logical Shift Left (immediate) shifts a register value left by an immediate number of bits, shifting in zeros, and writes the result to the destination register.

32-bit (sf == 0 && N == 0 && imms != 011111)

LSL <Wd>, <Wn>, #<shift>

is equivalent to

UBFM <Wd>, <Wn>, #(-<shift> MOD 32), #(31-<shift>)

and is the preferred disassembly when UInt(imms) + 1 == UInt(immr).

64-bit (sf == 1 && N == 1 && imms != 111111)

LSL <Xd>, <Xn>, #<shift>

is equivalent to

UBFM <Xd>, <Xn>, #(-<shift> MOD 64), #(63-<shift>)

and is the preferred disassembly when UInt(imms) + 1 == UInt(immr).

Assembler Symbols

<Wd>	Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field.

<Wn>	Is the 32-bit name of the general-purpose source register, encoded in the "Rn" field.

<shift>	For the 32-bit variant: is the shift amount, in the range 0 to 31.
	For the 64-bit variant: is the shift amount, in the range 0 to 63.

<Xd>	Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field.

<Xn>	Is the 64-bit name of the general-purpose source register, encoded in the "Rn" field.

Operation

The description of UBFM gives the operational pseudocode for this instruction.

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.

Internal version only: aarchmrs v2023-12_rel, pseudocode v2023-12_rel, sve v2023-12_rel ; Build timestamp: 2023-12-15T16:46

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
sf	1	0	1	0	0	1	1	0	N	immr						!= x11111						Rn					Rd
	opc															imms