//-------------------------------------------------------------------
//	dacproto.cpp
//
//	This testbed lets us see the effect of modifying the values 
//	that are programmed into the 256 DAC color-table registers.
//
//	   compile using:  $ dacproto.cpp int86.cpp -o dacproto
//
//	programmer: ALLAN CRUSE
//	written on: 20 NOV 2005
//-------------------------------------------------------------------

#include <stdio.h>	// for printf(), perror() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for exit() 
#include <unistd.h>	// for lseek() 
#include <termios.h>	// for tcgetattr(), tcsetattr() 
#include <sys/mman.h>	// for mmap() 
#include <sys/io.h>	// for outb()
#include "int86.h"	// for init8086(), int86() 

unsigned char *vram = (unsigned char*)0xA0000000; 
int   vesa_mode = 0x4101, hres = 640, vres = 480; 
struct vm86plus_struct	vm;
struct rgb_struct { unsigned char r, g, b; };

void reprogram_color_registers( struct rgb_struct *table )
{
	for (int color = 0; color < 256; color++)
		{
		outb( color, 0x3C8 );
		outb( table[ color ].r, 0x3C9 );	
		outb( table[ color ].g, 0x3C9 );	
		outb( table[ color ].b, 0x3C9 );	
		}
}

void draw_color_grid( void )
{
	int	wide = hres/16, high = vres/16;

	for (int color = 0; color < 256; color++)
		{
		int	horiz = color % 16;
		int	vertl = color / 16;
		int	x_start = wide * horiz;
		int	y_start = high * vertl;
		int	screen_offset = y_start * hres + x_start;
		int	box_margin = 5; 
		unsigned char	*destn = vram + screen_offset;
		for (int y = box_margin; y < high-box_margin; y++) 
			for (int x = box_margin; x < wide-box_margin; x++) 
				destn[ y*hres + x ] = color;
		}
}

int main( int argc, char **argv )
{
	int	fd = open( "/dev/vram", O_RDWR ); 
	if ( fd < 0 ) { perror( "/dev/vram" ); return -1; } 
	int	size = lseek( fd, 0, SEEK_END );
	int	prot = PROT_READ | PROT_WRITE; 
	int	flag = MAP_FIXED | MAP_SHARED; 
	if ( mmap( (void*)vram, size, prot, flag, fd, 0 ) == MAP_FAILED ) 
		{ perror( "mmap" ); return -1; } 

	struct termios	otty; 
	tcgetattr( 0, &otty ); 
	struct termios	tty = otty; 
	tty.c_lflag &= ~( ICANON | ECHO | ISIG ); 
	tty.c_cc[ VMIN ] = 1; 
	tty.c_cc[ VTIME ] = 0; 
	tcsetattr( 0, TCSAFLUSH, &tty ); 

	init8086();
	vm.regs.eax = 0x4F02;
	vm.regs.ebx = vesa_mode;
	int86( 0x10, vm );

	int	minx = 0, miny = 0, maxx = hres-1, maxy = vres-1;
	int	x = minx, y = miny, 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 ); 
	draw_color_grid();
	getchar();

	// design a new array of color values 
	int	b = 0, g = 64, r = 128, w = 192;
	struct rgb_struct color_table[ 256 ] = { 0 };
	for (int i = 0; i < 64; i++)
		{
		color_table[ r + i ].r = i;
		color_table[ g + i ].g = i;
		color_table[ b + i ].b = i;
		color_table[ w + i ].r = i;
		color_table[ w + i ].g = i;
		color_table[ w + i ].b = i;
		}	
	reprogram_color_registers( color_table );
	getchar();
	
	vm.regs.eax = 0x4F02;
	vm.regs.ebx = 0x0003;
	int86( 0x10, vm );
	tcsetattr( 0, TCSAFLUSH, &otty ); 
}