CODEWITHSUNDEEP
carguments64-bitnasm
BerretMan
BerretMan

Reputation: 83

Try to pass argument to C function in Nasm elf64 but it return SIGFPE error

I try to implement the C sqrt function in Nasm elf64, it works correctly without argument (with the value of "a" define in the function), but when I try to pass an argument to this function ,the code return an error "Stopped reason: SIGFPE".

Here's my code

The c function

int le_sqrt(int a) {
   int n=1;
   int number = a;
   for (int i=0; i<10; i++) {
       n=(n+number/n)/2;  
   }
   return n; 
}

The nasm program

bits 64
global _start
extern le_sqrt 

_start:
    mov rbp,9 ;argument 
    push rbp ;same argument push
    call le_sqrt ; my c function

    mov rax,60 ;exit program
    mov rsi,0
    syscall

Upvotes: 3

Views: 125

Answers (2)

Lakshay Rohila
Lakshay Rohila

Reputation: 189

SIGFPE usually happens when you divide a number by 0. In your assembly program, you are using mov rbp, 9 for passing an argument to c function, which might be wrong in your case. It becomes obvious since you're getting SIGFPE. See Microsoft calling conventions and System V ABI calling conventions (for 64-bit). For 32-bit, follow these calling conventions.

Upvotes: 1

Kolodez
Kolodez

Reputation: 635

If you want to call le_sqrt(9) with System V AMD64 ABI calling convention, do this:

_start:
    mov rdi,9
    call le_sqrt

Upvotes: 3

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