CODEWITHSUNDEEP
assemblynasm
Terry Mobley
Terry Mobley

Reputation: 17

Floating point in nasm

The code below always returns 0.0000000. I don't know why it is doing this.

here is the code

SECTION .data
flt1:   dq  5.327
formatin: db "%f", 0
SECTION .bss

SECTION .text
   global _main 

   extern _scanf 
   extern _printf     

_main:

    push ebp
    mov ebp, esp
push dword[flt1]    

push formatin
call _printf
add esp, 8


    mov esp, ebp
    pop ebp
    ret

can you help me fix this problem so I can display numbers with a decimal point

Upvotes: 1

Views: 2312

Answers (1)

Gold Dragon
Gold Dragon

Reputation: 480

In c function calls, float is promoted to double. You also declared flt1 as dq, a double. So regardless, you need to pass a 64-bit type. If you are on a 64-bit system, simply use push qword[flt1]. If you are on a 32-bit system, you will have to instead use fld. Because your parameter sizes are different, you will then have to use add esp, 12 rather than add esp, 8

Upvotes: 1

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