main.c

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

char executable_code[128];
typedef void(function_call)();

/* demo uses a simple return statement  (0xC3).
To proved the code is actually running
you can use a 0xCC which is a breakpoint
the code wiil abort with Trace/breakpoint trap
*/

int main(int argc, char *argv[]) {
  printf("Exec code in static memory\n");
  executable_code [0] = 0xC3; // flat mode near return
  function_call *f_static = (function_call *)&executable_code[0];
  (*f_static) ();

  printf("Exec code in malloc memory\n");
  char * allocated = (char*) malloc (128);
  allocated [0] = 0xC3; // flat mode near return
  function_call *f_malloc = (function_call *)&allocated[0];
  (*f_malloc) ();

  printf("Exec code in stack memory\n");
  char stack[128];
  stack [0] = 0xC3; // flat mode near return
  function_call *f_stack = (function_call *)&stack[0];
  (*f_stack) ();

  return 0;
}