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/* Shows DEGAS  PI1/PC1 pictures on your PC! */


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

FILE* f;
union REGS regs;

unsigned char far *screen;
unsigned int id;

main(int argc,char **argv)
{
unsigned char fname[80];

	if(argc > 1)
	{
		if(! (f = fopen(argv[1],"rb")) )
		{
			printf("Couldn't find %s!\n",argv[1]);
			exit(1);
		}

		screen = MK_FP(0xA000,0);
		setpal();

		if(id & 0x8000)
			load_pc();
		else
			load_pi();

		getch();

		set_text();
	}
	else
	{
		printf("DEGASHOW Atari Degas Elite picture viewer\n");
		printf("usage: degashow <filename.p?1>\n");
	}
}


load_pc()
{
unsigned int i,plane,scrstart;
unsigned int addr,scan,nextline;
unsigned char byte,b;

	dis_refresh();

	for(scan=0;scan < 200;scan++)
	{
		for(plane=0;plane < 4; plane++)              /* four bitplanes */
		{
			addr = 320*scan;
			nextline = addr + 320;
			do
			{
				byte = (unsigned char)getc(f);

				if(byte < 128)
				{
					for(i=0;i < byte+1; i++)
					{
						b = (unsigned char)getc(f);

						screen[addr++] |= (b >> 7 & 1) << plane;
						screen[addr++] |= (b >> 6 & 1) << plane;
						screen[addr++] |= (b >> 5 & 1) << plane;
						screen[addr++] |= (b >> 4 & 1) << plane;
						screen[addr++] |= (b >> 3 & 1) << plane;
						screen[addr++] |= (b >> 2 & 1) << plane;
						screen[addr++] |= (b >> 1 & 1) << plane;
						screen[addr++] |= (b & 1) << plane;
					}
				}
				else if(byte > 128)
				{
					b = (unsigned char)getc(f);

					for(i=0;i < (256-byte)+1; i++)
					{
						screen[addr++] |= (b >> 7 & 1) << plane;
						screen[addr++] |= (b >> 6 & 1) << plane;
						screen[addr++] |= (b >> 5 & 1) << plane;
						screen[addr++] |= (b >> 4 & 1) << plane;
						screen[addr++] |= (b >> 3 & 1) << plane;
						screen[addr++] |= (b >> 2 & 1) << plane;
						screen[addr++] |= (b >> 1 & 1) << plane;
						screen[addr++] |= (b & 1) << plane;
					}
				}
			} while(addr < nextline);
		}
	}
	fclose(f);
	ena_refresh();
}

load_pi()
{
unsigned int i,plane;
unsigned int addr,scan,nextline,offset;
unsigned char b;

	dis_refresh();

	for(scan=0;scan < 200;scan++)
	{
		addr = 320*scan;
		nextline = addr+320;
		offset = 0;

		do
		{
			for(plane=0;plane<4;plane++)
			{
				addr = 320*scan+offset;

				for (i=0;i<2;i++)
				{
					b = (unsigned char)getc(f);

					screen[addr++] |= (b >> 7 & 1) << plane;
					screen[addr++] |= (b >> 6 & 1) << plane;
					screen[addr++] |= (b >> 5 & 1) << plane;
					screen[addr++] |= (b >> 4 & 1) << plane;
					screen[addr++] |= (b >> 3 & 1) << plane;
					screen[addr++] |= (b >> 2 & 1) << plane;
					screen[addr++] |= (b >> 1 & 1) << plane;
					screen[addr++] |= (b & 1) << plane;
				}
			}
			offset += 16;
		} while(addr < nextline);
	}
	fclose(f);
	ena_refresh();
}



setpal()
{
int i;
unsigned colword;
unsigned char  red,green,blue;

	set_mcga();

	id = read16bit();

	for(i=0;i < 16 ;i++)
	{
		colword = read16bit();
		blue =  (unsigned char)((colword & 7) * 9) ;
		colword >>= 4;
		green =  (unsigned char)((colword & 7) * 9) ;
		colword >>= 4;
		red =  (unsigned char)((colword & 7) * 9) ;

		regs.h.ah = 0x10;
		regs.h.al = 0x10;
		regs.x.bx = i;
		regs.h.ch = green;
		regs.h.cl = blue;
		regs.h.dh = red;
		int86(0x10,&regs,&regs);
	}
}


int read16bit()
{
	int c1, c2;
	c1 = getc(f);
	c2 = getc(f);
	return to16bit(c1,c2);
}

int to16bit(c1,c2)
int c1, c2;
{
	return ((c1 & 0xff ) << 8) + (c2 & 0xff);
}


set_mcga()
{
	regs.h.ah = 0;                            /* MCGA mode, 320x200 */
	regs.h.al = 0x13;
	int86(0x10,&regs,&regs);
}

set_text()
{
	regs.h.ah = 0;                            /* MCGA mode, 320x200 */
	regs.h.al = 3;
	int86(0x10,&regs,&regs);
}

dis_refresh()
{
	regs.h.ah = 0x12;
	regs.h.al = 1;
	regs.h.bl = 0x36;
	int86(0x10,&regs,&regs);
}

ena_refresh()
{
	regs.h.ah = 0x12;
	regs.h.al = 0;
	regs.h.bl = 0x36;
	int86(0x10,&regs,&regs);
}
.

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