Subversion Repositories 395_vgs

#include <system.h>
#include "gpu_pic.h"
 
//Loads the source address (registers 0, 1, and 2) into the GPU 
void load_s_addr(unsigned long address)
{	
	portc = 0x02; 								//Load least significant byte
	portb = (char) (0x000000FF & address);
	porta = 0x01;								//enable load
	porta = 0x00;								//load complete
	address >>= 8;
	portc = 0x01; 								//Load middle byte
	portb = (char) (0x000000FF & address);
	porta = 0x01;								//enable load
	porta = 0x00;								//load complete
	address >>= 8;
	portc = 0x00; 								//Load most significant byte
	portb = (char) (0x000000FF & address);
	porta = 0x01;								//enable load
	porta = 0x00;								//load complete
	return;
}
 
void load_t_addr(unsigned long address)
{	
	portc = 0x05; 								
	portb = (char) (0x000000FF & address);
	porta = 0x01;								
	porta = 0x00;								
	address >>= 8;
	portc = 0x04; 								
	portb = (char) (0x000000FF & address);
	porta = 0x01;								
	porta = 0x00;							
	address >>= 8;
	portc = 0x03; 								
	portb = (char) (0x000000FF & address);
	porta = 0x01;							
	porta = 0x00;
	return;
}
 
void load_s_lines(unsigned lines)
{	
	portc = 0x07;
	portb = (char) (0x00FF & lines);
	porta = 0x01;
	porta = 0x00;
	lines >>= 8;
	portc = 0x06;
	portb = (char) (0x00FF & lines);
	porta = 0x01;
	porta = 0x00;
	return;
}
 
void load_l_size(unsigned size)
{	
	portc = 0x09;
	portb = (char) (0x00FF & size);
	porta = 0x01;
	porta = 0x00;
	size >>= 8;
	portc = 0x08;
	portb = (char) (0x000F & size);
	porta = 0x01;
	porta = 0x00;
	return;
}
 
void load_alphaOp( bool alphaOp)
{
	portc = 0x0A;
	if (alphaOp)
		portb = 0x01;
	else
		portb = 0x00;
	porta = 0x01;
	porta = 0x00;
	return;
}
 
void draw()
{
	porta = 00000010b;					//initialize draw
	porta = 00000000b;					//draw command recieved, so turn off draw bit
	while ( !(portd & 10000000b) )		//hang here till we recieve idle from GPU
	{
	}
}
 
 
//draw a fullscreen background
void drawtobackground ( Bitmap source )
{
	load_t_addr(0x00000000);
	load_s_addr(source.address);
	load_s_lines(source.lines);
	load_l_size(source.width);
	load_alphaOp(false);
	draw();
}
 
void drawsprite (Sprite sprite)
{
	unsigned long destination_address = sprite.position.y * 160;
	destination_address += sprite.position.x;
	load_t_addr(destination_address);
	load_s_addr(sprite.image.address);
	load_s_lines(sprite.image.lines);
	load_l_size(sprite.image.width);
	if (sprite.alpha)
		load_alphaOp(true);
	else
		load_alphaOp(false);
	draw();
}