#include <stdio.h>

#include <stdlib.h>

#include <dos.h>

#include <tiga.h>

#include <extend.h>

#include <typedefs.h>





CONFIG config;





struct pal {

	int r;

	int g;

	int b;

	} Pal[256];



int PX, PY;

int Xoff = 0;

int Yoff = 0;



int Width, Height;		/* Width and Height of the entire image */



int iWidth, iHeight;		/* Width and Height of sub-image */







static unsigned char outrow[1024] = {0};

static unsigned char ostack[4096] = {0};





static unsigned char cmask[9] = {0,1,3,7,0xf,0x1f,0x3f,0x7f,0xff};



static unsigned int rem = 0;



static int remct = 0;



static FILE *fp = NULL;

static int bufct = 0;



static int xsize = 0;

static int ysize = 0;

static int xadj = 0;

static int yadj = 0;



static int x = 0;

static int y = 0;

static int ix = 0;

static int iy = 0;

static int iw = 0;

static int ih = 0;



static int pass = 0;



static int rowcnt = 0;

static int done = 0;

static int interlaced = 0;



static unsigned char ctfirst[4096] = {0};

static unsigned char ctlast[4096] = {0};

static int ctlink[4096] = {0};



static int nextcode = 0;

static int nextlim = 0;









void inittiga()

{

int ip_result;

char outbuf[80];



	if (!(set_videomode(TIGA, INIT_GLOBALS | CLR_SCREEN) )) {

		printf("Error: set_videomode() has failed.\n");

		printf("Make sure that TIGACD has been loaded.\n");

		exit(-1);

		}





	/*

	 *

	 * Next, install the extended primitives.

	 *

	 * See page 3-99 of the TIGA-340 User's Guide for

	 * an explanation of the error result codes.

	 *

	 */



	 if (!function_implemented(DRAW_LINE)) {



		if ( (ip_result = install_primitives()) < 0) {

			set_videomode(PREVIOUS, INIT);

			printf("Error: install_primitives() has failed\n");

			printf("with an error code of %d.\n",ip_result);

			exit(-1);

			}



		}





	get_config(&config);







	init_text();



	set_fcolor(WHITE);



	set_bcolor(BLACK);



	sprintf(outbuf,"Current Display Mode: %d of %d",config.current_mode,

		config.num_modes);



	text_out(0,0,outbuf);



	sprintf(outbuf,"Resolution: %d by %d by %d bits",config.mode.disp_hres,

		config.mode.disp_vres, config.mode.disp_psize);



	text_out(0,20,outbuf);



	text_out(0,40,"Press a key to continue:");





	getch();



}





/*

 *	Put the card back in text mode

 */



void endtiga()

{



	set_videomode(PREVIOUS, INIT);



}









void FlushIn()

{

	do

	{

		while (bufct) {

			fgetc(fp);

			bufct--;

		}

	} while (bufct = fgetc(fp));

}







unsigned char getgb()

{

	unsigned char gb;



	if (bufct == 0) {

		bufct = fgetc(fp);

		if ((bufct == EOF) || (bufct == 0)) {

			endtiga();

			printf("Error: Unexpected End of Data");

			exit(2);

		}

	}

	if ((gb = fgetc(fp)) == EOF) {

		endtiga();

		printf("Error: Unexpected EOF");

		exit(1);

	}

	bufct--;

	return(gb);

}









unsigned char getbcode(reqct)

int	reqct;

{

	unsigned char retcode;



	if (remct == 0) {

		rem = getgb();

		remct = 8;

	}

	if (remct < reqct) {

		rem = rem | (((int) getgb()) << remct);

		remct += 8;

	}

	retcode = rem & cmask[reqct];

	remct -= reqct;

	rem = rem >> reqct;

	return(retcode);

}





unsigned int getcode(reqct)

int reqct;

{

	int	temp;



	if (reqct <= 8) return(getbcode(reqct));

	temp = getbcode(8);

	return((getbcode(reqct-8) << 8) | temp);

}





void init_codetable(cc)

int	cc;

{

	int	code = 0;



	nextcode = cc + 2;

	nextlim = cc << 1;

	while (code < cc) {

		ctfirst[code] = ctlast[code] = code;

		ctlink[code++] = -1;

	}

	while (code < 4096) ctlink[code++] = -2;

}





void insert_code(code, oldcode, csizeptr)

int code, oldcode, *csizeptr;

{

	ctlink[nextcode] = oldcode;

	ctlast[nextcode] = ctfirst[code];

	ctfirst[nextcode] = ctfirst[oldcode];

	if (++nextcode == nextlim) {

		if (*csizeptr < 12) {

			*csizeptr += 1;

			nextlim <<= 1;

		}

	}

}





void putpixel(val)

unsigned char val;

{



	set_fcolor(val);

	draw_point(PX + Xoff,PY + Yoff);



	PX++;

	if (PX == iWidth) {

		PX = 0;

		PY++;

		}



}





void putx(code, psize)

int code, psize;

{

	int ccount = 0;

	unsigned char *s;



	s=ostack;

	do

	{

		*s++ = ctlast[code];

		ccount++;

		code = ctlink[code];

	} while (code != -1);

	if (psize == 1) {

		do

		{

			putpixel(*--s & 1);

			putpixel(*s >> 1);

		} while (--ccount);

	}

	else do {

		putpixel(*--s);

	} while (--ccount);

}









void ximage(codestart,pixelsize)

int codestart,pixelsize;

{

	int reqct, code, cc, eoi, oldcode;



	cc = 1 << codestart;

	eoi = cc + 1;

	reqct = codestart + 1;

	init_codetable(cc);

	oldcode = -1;

	done = 0;

	pass = 0;

	rowcnt = iw;

	x = 0;

	y = 0;

	do {

		code = getcode(reqct);

		if (code == cc) {

			init_codetable(cc);

			reqct = codestart + 1;

			oldcode = -1;

		} else if (code == eoi) {

			FlushIn();

			done = -1;

		} else {

			if (ctlink[code] != -2) {

				if (oldcode != -1) insert_code(code, oldcode, &reqct);

			} else {

				insert_code(oldcode, oldcode, &reqct);

			}

			putx(code, pixelsize);

			oldcode = code;

		}



	} while (!done);





}









void bgfill(background)

unsigned char background;

{



	clear_page(background);





}







void getcolors(psize)

int psize;

{

	int cindex, cmax;



	cmax = 1 << psize;

	for (cindex = 0; cindex < cmax; cindex++) {





			Pal[cindex].r = fgetc(fp);

			Pal[cindex].g = fgetc(fp);

			Pal[cindex].b = fgetc(fp);



			set_palet_entry(cindex,Pal[cindex].r,Pal[cindex].g,Pal[cindex].b,0);



			}









}







/*

 *	Get a two-byte word (LSB first) from the file.

 *

 */



int gword()

{

	return(fgetc(fp) | (fgetc(fp) << 8));

}







main(int argc,char *argv[])

{

	int	n;

	int	alldone, bitspixel, pixelsize, csize, blen;

	unsigned char sflags, background, work, iflags;

	char namework[64];







	if (argc != 2) {

		printf("Usage: gsgif filename\n");

		exit(-1);

		}







	if ( ( fp = fopen(argv[1],"rb") ) == NULL) {

		strcpy(namework,argv[1]);

		strcat(namework,".GIF");



		if ( ( fp = fopen(namework,"rb") ) == NULL) {

			printf("Error: File Not Found");

			exit(-1);

			}



		}





	if (fgetc(fp) != 'G') {

		printf("Error: Invalid File Format\n");

		exit(1);

	}

	for (n=1;n<=5;n++) fgetc(fp);



	Width = gword();

	Height = gword();



	sflags = fgetc(fp);

	bitspixel = (sflags & 7) + 1;



	background = fgetc(fp);



	if (fgetc(fp)) {

		printf("Error: Invalid File Format\n");

		exit(1);

	}



	inittiga();



	if (config.mode.disp_hres > Width) Xoff = ( (config.mode.disp_hres - Width) / 2);

	if (config.mode.disp_vres > Height) Yoff = ( (config.mode.disp_vres - Height) / 2);



	if (sflags & 0x80) getcolors(bitspixel);



	bgfill(background);



	alldone = 0;



	while (!alldone && ((work = fgetc(fp)) != EOF)) {

		if (work == ',') {



			Xoff += gword();		/* center the image */

			Yoff += gword();

			iWidth = gword();

			iHeight = gword();



			iflags = fgetc(fp);

			interlaced = iflags & 0x40;

			if (interlaced) {

				endtiga();

				printf("Error: Can't handle interlaced image.");

				exit(-1);

				}



			pixelsize = bitspixel;



			if (iflags & 0x80) {

				pixelsize = (iflags & 7) + 1;

				getcolors(pixelsize);				/* only last map used */

			}



			csize = fgetc(fp);

			bufct = 0;

			ximage(csize, pixelsize);



		} else if (work == '!') {

			fgetc(fp);

			while (blen = fgetc(fp)) {

				for (n=0; n<blen; n++) fgetc(fp);

			}

		} else if (work = ';') alldone = -1;

		else {

			endtiga();

			printf("Error: Invalid File Format\n");

			exit(1);

		}

	}

	getch();

	endtiga();



}