CODEWITHSUNDEEP
assemblyx86attmovaddressing-mode
anonymous
anonymous

Reputation:

What is the meaning of MOV (%r11,%r12,1), %edx?

What does this instruction do?

mov (%r11,%r12,1), %edx

Upvotes: 6

Views: 2916

Answers (2)

dikamilo
dikamilo

Reputation: 667

mov (%r11,%r12,1), %edx this instruction is use to calculate the address (indexed addressing mode).

  • %r11 is a base adress
  • %r12 is a index
  • and 1 is a multipler

It's work like this:

adres = base adres + index * multipler

base adres and multipler must be constants (base adress can be register), index must be register.

Upvotes: -1

nc3b
nc3b

Reputation: 16270

Look here. It says

In the AT&T Syntax, memory is referenced in the following way,

segment-override:signed-offset(base,index,scale)

Down on the page there are some examples. I find this the best:

GAS memory operand   NASM memory operand
------------------   -------------------
(%ecx,%ebx,2)    [ecx+ebx*2]

mov source, destination in AT&T syntax copies the value from source to destination. Also consider the size of edx. How many bytes (4) do you think mov will copy ?

Upvotes: 8

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