2.6.5.3.1 Syntax

op{S}{cond} Rd, Rm, Rs

op{S}{cond} Rd, Rm, #n

RRX{S}{cond} Rd, Rm

where:

• op is one of:
  • ASR: Arithmetic Shift Right.
  • LSL: Logical Shift Left.
  • LSR: Logical Shift Right.
  • ROR: Rotate Right.
• S is an optional suffix. If S is specified, the condition code flags are updated on the result of the operation, see 2.6.3.7 Conditional Execution.
• Rd is the destination register.
• Rm is the register holding the value to be shifted.
• Rs is the register holding the shift length to apply to the value in Rm. Only the least significant byte is used and can be in the range 0 to 255.
• n is the shift length. The range of shift length depends on the instruction:
  • ASR shift length from 1 to 32
  • LSL shift length from 0 to 31
  • LSR shift length from 1 to 32
  • ROR shift length from 1 to 31
    Important: MOVS Rd, Rm is the preferred syntax for LSLS Rd, Rm, #0.