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linuxassemblyx86-64att

Why does move copy variable address to register, in x64 assembly?

I made a program in x64 assembly, using AT&T syntax, but I don't figure out why mov operator copies address variable to register. Here is my code:

        .globl main

        .text
main:
    mov    $a, %rax

    mov     $format, %rdi           # set 1st parameter (format)
    mov     %rax, %rsi              # set 2nd parameter (current_number)
    mov     $0, %rax                # because printf is varargs

    sub     $8, %rsp                # align stack pointer
    call    printf                  # printf(format, sum/count)
    add     $8, %rsp                # restore stack pointer

    ret

        .data
a:      .quad   123
format: .asciz  "%d\n"

The program outputs 6295616 instead of 123. Please help me understand what I've done wrong.

Solution

  • Because you have indicated with the dollar sign that you want immediate mode. Remove it to get absolute mode.