/*
	TCLR.C Ver 0.02 1991.08.09  by Y.Kurihara (Nif PDC01620)"
		T-MENU の画面にちょっかいを出すプログラム  その１

	(1) TCLR
	(2) TCLR  <Ｘ座標> <Ｙ座標> <桁数> <行数>

	(1) 全画面をクリア
	(2) 指定範囲をクリアする
*/

#include <stdio.h>
#include <stdlib.h>
#include <dos.h>
#include <machine.h>

#define  X0	(2)
#define  Xl	(76)
#define  Y0	(7)
#define  Yl	(20)

#define VRAM( offset )  ( (char far *)MK_FP( 0xc000,( offset ) ) )
#define PORTpage     (0xff83)
#define PORTplane    (0xff81)
#define Y1page       (256)


void clr( int x1,int y1,int x2,int y2 )
{
	unsigned int x,y;
	unsigned int off;

	if( y1 < Y1page ) {
		outp( PORTpage, 0x00 );
		off = y1 * 128;
	} else {
		outp( PORTpage, 0x10 );
		off = ( y1 - Y1page )* 128;
	}
	for( y = y1; y <= y2; y++ ) {
		if( y == Y1page ) {
			outp( PORTpage, 0x10 );
			off -= Y1page * 128;
		}
		for( x = x1; x <= x2; x++ ) {
			*VRAM( off + x ) = 0xff;
		}
		off += 128;
	}
	return;
}

main( int argc,char **argv )
{
	int save_page;
	int save_plane;
	int x1 = X0;
	int y1 = Y0;
	int x2 = Xl;
	int y2 = Yl;

	if( argc >= 2 )  x1 = atoi( argv[1] );
	if( argc >= 3 )  y1 = atoi( argv[2] );
	if( argc >= 4 )  x2 = atoi( argv[3] );
	if( argc >= 5 )  y2 = atoi( argv[4] );

	if( x1 < 0 || y1 < 0 || x2 < 1 || y2 < 1 )  exit(1);
	if( x1 >= 80 || y1 >= 30 )  exit(1);
	if( ( x2 = x1 + x2 - 1 ) >= 80 )  x2 = 79;
	if( ( y2 = y1 + y2 - 1 ) >= 30 )  y2 = 29;

	if( argc < 2 ) {
		y1 = y1 *16 - 4;
		y2 = y2 *16 + 19;
	} else {
		y1 = y1 *16;
		y2 = y2 *16 + 15;
	}

	save_page  = inp( PORTpage );
	save_plane = inp( PORTplane );
	outp( PORTplane,15 );

	clr( x1,y1,x2,y2 );

	outp( PORTpage,  save_page );
	outp( PORTplane, save_plane );
	exit( 0 );
}