Flood fill/C example

This flood fill code is adapted from a Tetris clone called "Tetanus On Drugs" by Damian Yerrick. It's licensed under the GNU General Public License and comes with ABSOLUTELY NO WARRANTY.

#define BOARD_WIDTH  10
#define BOARD_HEIGHT 20

typedef struct MAP
{
  unsigned char b[BOARD_HEIGHT][BOARD_WIDTH];
} MAP;

static void flood_loop(MAP *map, int x, int y, unsigned int dst_c, unsigned int src_c)
{
  int fillL, fillR, i;
  int in_line = 1;

  /* find left side, filling along the way */
  fillL = fillR = x;
  while(in_line)
  {
    map->b[y][fillL] = dst_c;
    fillL--;
    in_line = (fillL < 0) ? 0 : (map->b[y][fillL] == src_c);
  }
  fillL++;

  /* find right side, filling along the way */
  in_line = 1;
  while(in_line)
  {
    map->b[y][fillR] = c;
    fillR++;
    in_line = (fillR > 9) ? 0 : (map->b[y][fillR] == fillC);
  }
  fillR--;

  /* search top and bottom */
  for(i = fillL; i <= fillR; i++)
  {
    if(y > 0 && map->b[y - 1][i] == fillC)
	flood_loop(map, i, y - 1, c, fillC);
    if(y < BOARD_HEIGHT && map->b[y + 1][i] == fillC)
	flood_loop(map, i, y + 1, c, fillC);
  }
}

void flood_fill(MAP *map, int x, int y, unsigned int c)
{
  flood_loop(map, x, y, c, map->b[y][x]);
  map->b[y][x] = c;  /* some buggy optimizers needed this line */
}