calling assembly function from c

I'm trying to call an assembly function from c,but i keep getting errors.

    .text
    .globl integrate
    .type integrate, @function
integrate:
    push %ebp
    mov %esp, %ebp
    mov $0,%edi
start_loop:                
    cmp %edi,1024           
    je loop_exit
    mov 8(%ebp),%eax          
    mov 12(%ebp),%ecx          
    sub %eax,%ecx              
    add %edi,%ecx
    incl %edi                
    jmp start_loop             
loop_exit:                 
    movl %ebp, %esp
    popl %ebp
    ret   

This is my assembly function,file called integrate.s.

#include <stdio.h>

extern int integrate(int from,int to);

void main()
{
    printf("%d",integrate(1,10));
}

Heres my c code.

function.c:5:6: warning: return type of ‘main’ is not ‘int’ [-Wmain]
/tmp/cciR63og.o: In function `main':
function.c:(.text+0x19): undefined reference to `integrate'
collect2: ld returned 1 exit status

Whenever i try to compile my code with gcc -Wall function.c -o function,it gives the 'undefined reference to integrate' error.I also tried adding link to the integrate.s file from c,like

#include<(file path)/integrate.s>

but it didnt work as well.Btw what assembly code is doing is not important,for now im just trying to call the function from c successfully.Can anyone help me about solving this problem ?