//=========================================================================
#define PROGRAMMER "BAHN, William"
#define PROG_CODE  "bahw"
#define COURSE     "ECE-1021"
#define YEAR       (2003)
#define TERM       "Fall"
#define SECTION    (0)
#define ASSIGNMENT "RWA 5.9"
#define REVISION   (0)
#define TITLE      "Real World Application from Section 5.9"
#define SUBTITLE   "Recursive Tiling"
#define EMAIL      "wbahn@eas.uccs.edu"
#define FILENAME   "rwa0509.c"
//=========================================================================

//== INCLUDE FILES ========================================================
#include <stdio.h> // putchar()
#include <conio.h> // gotoxy()
#include <math.h>  // pow()

//== FUNCTION PROTOTYPES ==================================================
void PrintHeader(void);
void tile(int x, int y, int size, int xm, int ym);
int GetOrder(void);
int GetXmiss(void);
int GetYmiss(void);

//== MAIN FUNCTION ========================================================
int main(void)
{
	int order, size;
	int xmiss, ymiss;

	PrintHeader();
	printf("\n"); // Print a blank line

	order = GetOrder();
	xmiss = GetXmiss();
	ymiss = GetYmiss();

	size = pow(2, order);

	tile(60, 9, size, 60+xmiss, 9+ymiss);

	return(0);
}

//== SUPPORT FUNCTIONS ====================================================
void PrintHeader(void)
{
	printf("========================================"
			 "=======================================\n");
	printf("Course....... %s-%i (%s %i)\n", COURSE, SECTION, TERM, YEAR);
	printf("Programmer... %s (%s)\n", PROGRAMMER, PROG_CODE);
	printf("Assignment... %s (Rev %i) (Source Code in %s)\n",
		ASSIGNMENT, REVISION, FILENAME);
	printf("Description.. %s\n", TITLE);
	printf("              %s\n", SUBTITLE);
	printf("========================================"
			 "=======================================\n");

	return;
}

int GetOrder(void)
{
	int i;

	printf("Enter the 'n' value (size is 2^n per side): ");
	scanf("%i", &i);
	printf("\n");
	printf("NOTE: Tile (0,0) is the upper left corner.\n");
	printf("\n");
	return(i);
}

int GetXmiss(void)
{
	int i;

	printf("Enter the x value of the missing tile: ");
	scanf("%i", &i);
	return(i);
}

int GetYmiss(void)
{
	int i;

	printf("Enter the y value of the missing tile: ");
	scanf("%i", &i);
	return(i);
}

void tile(int x, int y, int size, int xm, int ym)
{
	static char gsym = ' ';

	int r, c;
	int xmlh, ymuh;

	if (2 == size)  // Base Case
	{
		gsym++;
		for(r = y; r < y + size; r++ )
			for(c = x; c < x + size; c++ )
			{
				gotoxy(c, r);
				if(! ((c == xm) && (r == ym)) )
					putchar(gsym);
			}
	}
	else
	{
		size /= 2;

		// Set offsets
		xmlh = xm < x + size; // tile is missing in Left Half
		ymuh = ym < y + size; // Tile is missing from Upper Half

		// Tile the lateral half that the missing tile is NOT in
		tile(x+size *  xmlh, y,      size, x+size, y+size-1); // Upper
		tile(x+size *  xmlh, y+size, size, x+size, y+size);   // Lower

		// Tile the Quadrant with the Missing Tile
		tile(x+size * !xmlh, y+size * !ymuh, size, xm, ym);

		// Tile the Quadrant without the Missing Tile
		tile(x+size * !xmlh, y+size *  ymuh, size, x+size-xmlh, y+size-!ymuh);

		// Tile the Overlap of the three full quadrants
		tile(x+size-1, y+size-1, 2, x+size-xmlh, y+size-ymuh);
	}

	return;
}