#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>

#define IO_REGS_LENGTH 0x80000
// GMU No longer needed
//#define IO_BASE_ADDR   0xe0080000


off_t  get_offset(char *argv1)
{
  char  *c       = strchr(argv1, 'x');
  off_t  io_base = 0x0;


  if (c != NULL)
  {
    sscanf(argv1, "%lx", &io_base);
  }
  else  // no 'x' in the string, must be an integer instead of a hex value
  {
    // Is this valid?
    io_base = atol(argv1);
  }


  return io_base;
}



int main(int argc, char *argv[]) 
{
  unsigned long *MMIOBase;
  unsigned long  swf1;
  int            fd;
  off_t          io_base_addr;

  if (argc != 2)
  {
    fprintf(stderr, "Usage:\n\t%s <offset>\n\n\tWhere <offset> is base address of Display Controller 32-bit, non-prefetchable memory.\n\tHint: use /sbin/lspci -v to obtain this value.\n", argv[0]);
    return -1;
  }

  io_base_addr = get_offset(argv[1]);

  if ((fd = open("/dev/mem", O_RDWR)) < 0) 
  {
    fprintf(stderr, "Cannot open /dev/mem\n");
    return -1;
  }

//  MMIOBase = (unsigned long *)mmap(NULL, IO_REGS_LENGTH, PROT_READ | PROT_WRITE, MAP_SHARED, fd, (off_t)IO_BASE_ADDR);
  MMIOBase = (unsigned long *)mmap(NULL, IO_REGS_LENGTH, PROT_READ | PROT_WRITE, MAP_SHARED, fd, io_base_addr);
  
  if (MMIOBase == (unsigned long *)-1) 
  {
    close(fd);
    perror("IOBase ");
    fprintf(stderr, "Can't map MMIOBase\n");
    return -1;
  }
  swf1 = MMIOBase[0x71414/4];

  printf("SWF1 before = 0x%8.8X\n", swf1);
  swf1 &= ~0xf;
  swf1 |= 8;
  printf("SWF1 after  = 0x%8.8X\n", swf1);

  MMIOBase[0x71414/4] = swf1;

  munmap(MMIOBase, IO_REGS_LENGTH);
  close(fd);
  return 0;
}