driver_ex2.c

#ifndef CDECL_HEADER_FILE
#define CDECL_HEADER_FILE

/*
 * Define macros to specify the standard C calling convention
 * The macros are designed so that they will work with all
 * supported C/C++ compilers.
 *
 * To use define your function prototype like this:
 *
 * return_type PRE_CDECL func_name( args ) POST_CDECL;
 *
 * For example:
 *
 * int PRE_CDECL f( int x, int y) POST_CDECL;
 */

#if defined(__GNUC__)
#define PRE_CDECL
#define POST_CDECL __attribute__((cdecl))
#else
#define PRE_CDECL __cdecl
#define POST_CDECL
#endif

#endif

#include <stdio.h>
#include <stdlib.h>

float compute_derivative(float (*f)(float),float x, float epsilon);

int PRE_CDECL asm_main( void ) POST_CDECL;

float f(float x) {
  return (x*x + 10.0/x);
}

int main(int argc, char **argv)
{
  float derivative;
  float x, epsilon;

  if (argc != 3) {
    fprintf(stderr,"Usage: %s <x> <epsilon>\n",argv[0]);
    exit(1);
  }

  if (sscanf(argv[1],"%f",&x) != 1) {
    fprintf(stderr,"Invalid command-line argument '%s'\n",argv[1]);
    exit(1);
  }

  if (sscanf(argv[2],"%f",&epsilon) != 1) {
    fprintf(stderr,"Invalid command-line argument '%s'\n",argv[2]);
    exit(1);
  }


  derivative = compute_derivative(f, x, epsilon);
  printf("Derivative of function f at point %f is %.5f\n",x,derivative);

  exit(0);
}