//-------------------------------------------------------------------
//	brickpat.cpp
//
//	This demo shows how a graphics application draws patterns. 
//
//	programmer: ALLAN CRUSE
//	written on: 13 SEP 2003
//-------------------------------------------------------------------

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

#define VRAM_BASE_ADDRESS 0x000A0000
#define VGA_WINDOW_LENGTH (64 << 10)

unsigned char	*vram = (unsigned char *)VRAM_BASE_ADDRESS;
int	mode = 19, hres = 320, vres = 200;

char brickpat[ 8 ] = { 0xFF, 0x80, 0x80, 0x80, 0xFF, 0x08, 0x08, 0x08 };
void fill_rect( int x, int y, int h, int v, int fg, int bg, char *pat );
int map_system_memory( int base, int size );


int main( int argc, char **argv )
{
	// map the VRAM into application's virtual address-space
	map_system_memory( VRAM_BASE_ADDRESS, VGA_WINDOW_LENGTH );

	// enter graphics mode
	char	command[ 40 ];
	sprintf( command, "clear ; mode3 %d ", mode );
	system( command ); 

	// draw screen border
	int	minx = 0, maxx = hres-1, miny = 0, maxy = vres-1;
	int	x = 0, y = 0, color = 15;
	do { vram[ y*hres + x ] = color; ++x; } while ( x < maxx );	
	do { vram[ y*hres + x ] = color; ++y; } while ( y < maxy );	
	do { vram[ y*hres + x ] = color; --x; } while ( x > minx );	
	do { vram[ y*hres + x ] = color; --y; } while ( y > miny );	
	getchar();
	
	// fill the screen area with our 2-color brick pattern
	int	red = 4, white = 15;
	fill_rect( 1, 1, hres-2, vres-2, white, red, brickpat );
	getchar();

	// restore text mode
	system( "mode3" );
}



void fill_rect( int x, int y, int h, int v, int fg, int bg, char *pat )
{
	int	minx = x, maxx = x+h-1, miny = y, maxy = y+v-1;
	
	for (y = miny; y <= maxy; y++)
	for (x = minx; x <= maxx; x++)
		{
		int	r = y % 8;	
		int	k = x % 8;
		int	color = ( pat[ r ] & (0x80>>k) ) ? fg : bg;
		vram[ y*hres + x ] = color;
		}
}


int 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/mem", O_RDWR );
	if ( fd < 0 ) { perror( "/dev/mem" ); exit(1); }
	if ( mmap( mm, size, prot, flag, fd, base ) == MAP_FAILED )
		{ perror( "mmap" ); exit(1); }
	close( fd );
	return	0;
}