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LSLV

Logical shift left variable

This instruction shifts a register value left by a variable number of bits, shifting in zeros, and writes the result to the destination register. The value of the second source register modulo the register size in bits gives the number of bits by which the first source register is left-shifted.

This instruction is used by the alias LSL (register).

313029282726252423222120191817161514131211109876543210
sf0011010110Rm001000RnRd
Sop2

32-bit encoding

(sf == 0)

LSLV <Wd>, <Wn>, <Wm>

64-bit encoding

(sf == 1)

LSLV <Xd>, <Xn>, <Xm>

Decode (all encodings)

constant integer d = UInt(Rd); constant integer n = UInt(Rn); constant integer m = UInt(Rm); constant integer datasize = 32 << UInt(sf); constant ShiftType shift_type = DecodeShift(op2);

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 first general-purpose source register, encoded in the "Rn" field.

<Wm>

Is the 32-bit name of the second general-purpose source register holding a shift amount from 0 to 31 in its bottom 5 bits, encoded in the "Rm" field.

<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 first general-purpose source register, encoded in the "Rn" field.

<Xm>

Is the 64-bit name of the second general-purpose source register holding a shift amount from 0 to 63 in its bottom 6 bits, encoded in the "Rm" field.

Operation

constant bits(datasize) operand2 = X[m, datasize]; X[d, datasize] = ShiftReg(n, shift_type, UInt(operand2) MOD datasize, datasize);

Operational information

This instruction is a data-independent-time instruction as described in About PSTATE.DIT.

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