#ifndef _DISPLAY_H
#define _DISPLAY_H

// NTSC horizontal sync pulses occur at 63.55 microseconds.
// We will make our cycles 63.625 microseconds.  
// Clock: 16 MHz    Interrupt when counter is at: 1018.
#define _DISP_LINE_TIME 1018
// Top and bottom line numbers of the viewable portion of the screen
#define _DISP_SCREEN_TOP 30
#define _DISP_SCREEN_BOTTOM 230
#define _DISP_HEIGHT 100
// Sync is when Video Output = 0V.  No pins are asserted
#define _DISP_SYNC 0x00;
// Low is when Video Port Pin 5 is asserted, which correspons to black ~ 0.3 V.
#define _DISP_LOW  0x20;

extern int lineCount;   // The current scanline number to be outputed.
extern char syncOn;     // The output for video out when sync is ON.
extern char syncOff;    // The output for video out when sync is OFF.
extern char screen[1600]; // The TV screen buffer.

/** Flags Bits **/
#define RENDER_SHIP_1 0x1
#define RENDER_SHIP_2 0x2
#define RENDER_BULLET 0x4 
#define RENDER_EXPLODE 0x10  
#define RENDER_PLANET 0x20   
#define RENDER_ERROR  0x80

/** Last Screen Index for last line */	
#define MAX_SCREEN_LINE 1584

/**
* Zoom Mode Enable.
* @param x     The horizontal coordinate for top left corner of zoom.
* @param y     The vertical coordinate for top left corner of zoom.
* @returns     Whether zoom was successful. (0 if unsuccessful).
*/
char zoomEnable (char x, char y);

/**
* Zoom Mode Disable.
*/
void zoomDisable();

/**
* returns whether we are in zoom mode.
*/
char isZoomed();

/**
* Initalize Display Parameters
*/
void initializeDisplay();

/** 
* Clears the screen. - Might be slow.
*/
void clearScreen();

/**
* Draws ship for player on screen.
* @param x      The horizontal coordinate for the center of the ship.
* @param y      The vertical coordinate for the center of the ship.
* @param theat  The angle of ship's orientation (0 to NUM_ANGLES - 1) 
* @param type   The ship type.
* @param player The player number 0 or 1.
*/ 
void drawShip(char x, char y, char theta, char type, char player);

/** 
* Erases the ship from screen.
* @param player  The player number 0 or 1.
*/
void eraseShip(char player);

/**
* Renderes the ships on the screen.  Must be called every frame.
*/
void renderShip();

/**
* Draw Bullet on screen
* @param x     The horizontal coordinate for the center of the bullet.
* @param y     The vertical coordinate for the center of the bullet.
* @param theta The angle of bullet's orientation.
* @param type  The type of bullet.
* @param player The player who fired the bullet.
*/
void drawBullet(char x, char y, char theta, char type, char player);

/**
* Erase the bullets from screen fired by the given player.
* @param player The player who fired the bullets.
*/
void eraseBullets(char player);

/**
* Render all the bullets.
* @param Render bullets for player.
*/
void renderBullets(char player); 

/**
* Draw Explosion on screen
* @param x     The horizontal coordinate for the center of the explosion.
* @param y     The vertical coordinate for the center of the explosion.
* @param type  The type of explosion effect (Frame #).
*/
void drawExplosion(char x, char y,  char type);

/**
* Erase the all the explosions from screen.
*/
void eraseExplosions();

/**
* Render all the explosions.
*/
void renderExplosions();  

/**
* Draw Planet on Screen.
*/
void drawPlanet();

/**
* Render the Planet. drawPlanet call is required.
*/
void renderPlanet();

/**
* Draw a Big Ship @ (x,y) - Top Left Corner.
* @param xCoord Top Left x-coordinates
* @param yCoord Top Left y-coordinates.
* @param type The ship type
*/
void drawBigShips(signed char xCoord, signed char yCoord, char type);
#endif