ARM VERSION 1.2 manual Flexible offset syntax

ARM Instruction Reference

Flexible offset syntax

Both pre-indexed and post-indexed offsets can be either of the following:

#expr

{-}Rm{, shift}

where:

-is an optional minus sign. If - is present, the offset is subtracted from Rn. Otherwise, the offset is added to Rn.

expr	is an expression evaluating to an integer in the range –4095 to +4095.
	This is often a numeric constant (see examples below).
Rm	is a register containing a value to be used as the offset. Rm must not be r15.
shift	is an optional shift to be applied to Rm. It can be any one of:
ASR n
		arithmetic shift right n bits. 1 ≤ n ≤ 32.
LSL n
		logical shift left n bits. 0 ≤ n ≤ 31.
LSR n
		logical shift right n bits. 1 ≤ n ≤ 32.
ROR n
		rotate right n bits. 1 ≤ n ≤ 31.
	RRX	rotate right one bit, with extend.

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