//-------------------------------------------------------------------
//	quikcopy.cpp
//
//	This program shows how a graphics application written in C++
//	can call an external procedure written in assembly language.
//
//	 compile: g++ quikcopy.cpp int86.cpp copypage.o -o quikcopy
//
//	programmer: ALLAN CRUSE
//	written on: 03 DEC 2003
//	revised on: 06 OCT 2005 -- replaced svgalib with 'int86()'
//-------------------------------------------------------------------

#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 "int86.h"	// for init8086(), int86()

extern "C" void copypage( int src_pgno, int dst_pgno, int pagesz );

unsigned char *vram = (unsigned char*)0xA0000000; 
const int vesa_mode = 0x4101, hres = 640, vres = 480; 
struct vm86plus_struct	vm;

void draw_rectangle( int x, int y, int h, int v, int color ) 
{
	int	minx = x, miny = y, maxx = x+h-1, maxy = y+v-1; 

	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 ); 
}

void fill_rectangle( int x, int y, int h, int v, unsigned char *pat )
{
	int	minx = x, miny = y, maxx = x+h-1, maxy = y+v-1; 

	for (y = miny; y < maxy; y++) for (x = minx; x < maxx; x++)
		vram[ y*hres + x ] = pat[ ((y/4) % 4)*4 + ((x/4) % 4) ]; 
}

int main( int argc, char **argv )
{
	// memory-map the display-memory into user-space
	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; } 

	// enable non-canonical keyboard input
	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 ); 

	// enter graphics mode
	init8086();
	vm.regs.eax = 0x04F02;
	vm.regs.ebx = vesa_mode;
	int86( 0x10, vm );

	// draw border rectangle
	int	color = 15; 
	draw_rectangle( 0, 0, hres, vres, color ); 
	getchar(); 

	//-----------------------------------------------------------
	// draw rectangle on page 1, then copy from page 1 to page 0
	//-----------------------------------------------------------
	color = 14;
	draw_rectangle( 0, vres, hres, vres, color );
	copypage( 1, 0, hres*vres );	//<-- call external function
	getchar();
	//-----------------------------------------------------------

	//-----------------------------------------------------------
	// draw a pattern on page 1, then copy from page 1 to page 0
	//-----------------------------------------------------------
	unsigned char	pattern[ 16 ];	// for 4x4 bitmap pattern
	for (int i = 0; i < 16; i++) pattern[ i ] = random();
	fill_rectangle( 4, vres+4, hres-8, vres-8, pattern );
	color = 6;
	draw_rectangle( 2, vres+2, hres-4, vres-4, color );
	copypage( 1, 0, hres*vres );	//<-- call external function
	getchar();
	//-----------------------------------------------------------

	// leave graphics mode
	vm.regs.eax = 0x0003;
	int86( 0x10, vm );

	// restore canonical keyboard input
	tcsetattr( 0, TCSAFLUSH, &otty ); 
	printf( "finished\n" );
}