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arm instruction query

Hi All, Could any one of tell me what does the plus sign in the undermentioned denote.

LDR r3, [r0,+r1,LSL #1]

Without the plus sign its just a simple load instruction.

regards ashu

Reply to
ashu
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AFAICT, this plus sign is just the unary positive operator, and it is used to stress the "offset" nature of r1.

formatting link

A5.2 Addressing Mode 2 - Load and Store Word or Unsigned Byte

  1. [, +/-, #] See Load and Store Word or Unsigned Byte - Scaled register offset on page A5-22.

Syntax One of: [, +/-, LSL #] [, +/-, LSR #] [, +/-, ASR #] [, +/-, ROR #] [, +/-, RRX] where: Specifies the register containing the base address. Specifies the register containing the offset to add to or subtract from Rn.

So your instruction would compute addr = r0 + (r1

Reply to
Noob

denote.

A5-22.

Rn.

thanks so much Noob. The explanation really helped.

Reply to
ashu

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