Problems compiling assembly file - Error: undefined reference to `function name' - c

Question

I am trying to take a look at a test program my professor gave us, but I am having trouble compiling it. I am on Ubuntu 14.04. I am compiling it with
gcc -Wall test.c AssemblyFunction.S -m32 -o test
I was having problems running the code on a 64-bit machine and read that adding -Wall and -m32 will allow it to work. Doing that fixed the first problem I had, but now I am getting the error: undefined reference to `addnumbersinAssembly'.
Here is the C file
#include <stdio.h>
#include <stdlib.h>
extern int addnumbersinAssembly(int, int);
int main(void)
{
int a, b;
int res;
a = 5;
b = 6;
// Call the assembly function to add the numbers
res = addnumbersinAssembly(a,b);
printf("\nThe sum as computed in assembly is : %d", res);
return(0);
}
And here is the assembly file
.global _addnumbersinAssembly
_addnumbersinAssembly:
pushl %ebp
movl %esp,%ebp
movl 8(%ebp), %eax
addl 12(%ebp), %eax # Add the args
movl %ebp,%esp
popl %ebp
ret
Thank you for your time. I have been trying to figure this out for hours, so I appreciate any help.

Answer 1

I believe that with GCC you are going to want to remove the _ in your assembler file. So these lines:
.global _addnumbersinAssembly
_addnumbersinAssembly:
Should be:
.global addnumbersinAssembly
addnumbersinAssembly:
More information on this issue can be found in this StackOverflow question/answer.
The -m32 compile parameter is needed because the assembly code you have needs to be rewritten to support some 64 bit operations. In your case it was stack operations. The -Wall isn't needed to compile but it does turn on many more warnings.