Calling c function from x86 assembly code (cdecl)

func.c

#include <stdio.h>

int add_print(int a, int b) {
  int c = a + b;

  printf("%d + %d = %d\n", a, b, c);

  return c;
}

main.s

global main
extern add_print

section .text
main:
	; int eax = add_print(1, 2); // => 3
	push dword 2
	push dword 1
	call add_print
	add esp, 8

	; add_print(2, eax); // => 5
	push dword eax
	push dword 1
	call add_print
	add esp, 8

	; return 0;
	mov eax, 0
	ret

Makefile

OBJECTS = func.o main.o
CC = gcc
CFLAGS = -std=c11 -m32 -Wall -Wextra -Werror -c
AS = nasm
ASFLAGS = -f elf

all: $(OBJECTS)
	gcc -m32 $(OBJECTS) -o main

run: all
	./main

%.o: %.c
	$(CC) $(CFLAGS)  $< -o $@

%.o: %.s
	$(AS) $(ASFLAGS) $< -o $@

clean:
	rm -rf $(OBJECTS) main

It should be noted that if you're using an x64 change "-m32" in the Makefile to "-m64". It didn't work for me without doing that.