//-------------------------------------------------------------------
//	animate3.cpp
//
//	programmer: ALLAN CRUSE
//	written on: 01 OCT 2003
//-------------------------------------------------------------------

#include <stdio.h>	// for printf(), perror() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for exit() 
#include <unistd.h>	// for read(), write(), close() 
#include <sys/mman.h>	// for mman() 
#include <termios.h>	// for tcgetattr(), tcsetattr()

#define VRAM_BASE_ADDRESS 0xA0000000 
#define VGA_MEMORY_LENGTH ( 4 << 20) 

unsigned char	*vram = (unsigned char*)VRAM_BASE_ADDRESS;
const int display_mode = 0x4101, hres = 640, vres = 480;

void draw_segments( int x, int y, int xcent, int ycent, int color )
{
	int	minx = 0, miny = 0, maxx = hres-1, maxy = vres-1;
	int	xlo, xhi, v, h;

	xlo = xcent-x, xhi = xcent+x;
	if ( xlo < minx ) xlo = minx;
	if ( xhi > maxx ) xhi = maxx;

	if ( ( v = ycent-y ) >= miny )
		for (h = xlo; h <= xhi; h++) vram[ v*hres + h ] = color;
	if ( ( v = ycent+y ) <= maxy )
		for (h = xlo; h <= xhi; h++) vram[ v*hres + h ] = color;

	xlo = xcent-y, xhi = xcent+y;
	if ( xlo < minx ) xlo = minx;
	if ( xhi > maxx ) xhi = maxx;

	if ( ( v = ycent-x ) >= miny )
		for (h = xlo; h <= xhi; h++) vram[ v*hres + h ] = color;
	if ( ( v = ycent+x ) <= maxy )
		for (h = xlo; h <= xhi; h++) vram[ v*hres + h ] = color;
}	

void fill_circle( int x, int y, int radius, int color )
{
	int	xcent = x, ycent = y, decis = 3 - 2*radius;

	y = radius, x = 0;
	while ( x <= y )
		{
		draw_segments( x, y, xcent, ycent, color );
		if ( decis < 0 ) { decis += 4*x + 6; ++x; }
		else	{ decis += 4*(x - y) + 10; --y; ++x; }
		}	
}

void map_system_memory( int base, int size )
{
	int	prot = PROT_READ | PROT_WRITE; 
	int	flag = MAP_FIXED | MAP_SHARED; 
	void	*mm = (void*)base; 
	int	fd = open( "/dev/vram", O_RDWR ); 
	if ( fd < 0 ) { perror( "/dev/vram" ); exit(1); } 
	if ( mmap( mm, size, prot, flag, fd, 0 ) == MAP_FAILED ) 
		{ perror( "mmap" ); exit(1); } 
	close( fd ); 
}


int main( int argc, char **argv )
{
	struct termios	otty;
	tcgetattr( 0, &otty );
	struct termios	tty = otty;
	tty.c_lflag &= ~( ECHO | ICANON | ISIG );
	tty.c_cc[ VMIN ] = 1;
	tty.c_cc[ VTIME ] = 0;
	tcsetattr( 0, TCSAFLUSH, &tty );

	// map video memory into application's address-space	
	system( "/sbin/insmod vram.o" ); 
	map_system_memory( VRAM_BASE_ADDRESS, VGA_MEMORY_LENGTH ); 
	
	// enter graphics mode
	char	command[ 40 ];
	sprintf( command, " clear ; mode3 %d ", display_mode );
	system( command );

	// loop to draw several filled circles
	int	fgcolor = 14, bgcolor = 0, r = vres/16;
	int	x = hres/8, y = vres/4; 
	for (int i = 0; i < 4; i++)
	       	{	
		fill_circle( x, y, r, fgcolor );
		getchar();
		x += hres/4;
		}
		
	// this loop superimposes a triangle on one of the circles
	x -= hres/4;	
	for (int v = 0; v <= r; v++)
		for (int h = v+x; h <= x+r; h++) 
			{
			vram[ (y-v)*hres + h ] = bgcolor;
			vram[ (y+v)*hres + h ] = bgcolor;
			}
	getchar();

	// this loop superimposes a narrower triangle on another circle
	x -= hres/4;
	for (int v = 0; v <= r; v++)
		for (int h = v+v+x; h <= x+r; h++) 
			{
			vram[ (y-v)*hres + h ] = bgcolor;
			vram[ (y+v)*hres + h ] = bgcolor;
			}
	getchar();

	// this loop superimposes a still narrower triangle on another circle
	x -= hres/4;
	for (int v = 0; v <= r; v++)
		for (int h = v+v+v+v+x; h <= x+r; h++) 
			{
			vram[ (y-v)*hres + h ] = bgcolor;
			vram[ (y+v)*hres + h ] = bgcolor;
			}
	getchar();


	// build the array of sprite x-locations
	int	sprite[ 8 ] = {0};
	sprite[ 0 ] = 0*(hres/4);
	sprite[ 1 ] = 1*(hres/4);
	sprite[ 2 ] = 2*(hres/4);
	sprite[ 3 ] = 3*(hres/4);
	sprite[ 4 ] = 3*(hres/4);
	sprite[ 5 ] = 2*(hres/4);
	sprite[ 6 ] = 1*(hres/4);
	sprite[ 7 ] = 0*(hres/4);

	// start the bitblt loop to cycle through the sprite-array
	int	dstx = 0, dsty = vres/2;
	int	srcx = 0, srcy = 0;
	int	i = 0;
	while ( i < 256 )
		{
		srcx = sprite[ i%8 ];  dstx += 2;
		for (int v = 0; v <= vres/2; v++)
		for (int h = 0; h <= hres/4; h++)
		vram[ (dsty+v)*hres + dstx+h ] = vram[ (srcy+v)*hres + srcx+h ];
		getchar();
		++i;
		}
	getchar();
	
	// leave graphics mode
	system( "mode3 3" );
	tcsetattr( 0, TCSAFLUSH, &otty );
}