/**
 * $Id:$
 * ***** BEGIN GPL/BL DUAL LICENSE BLOCK *****
 *
 * The contents of this file may be used under the terms of either the GNU
 * General Public License Version 2 or later (the "GPL", see
 * http://www.gnu.org/licenses/gpl.html ), or the Blender License 1.0 or
 * later (the "BL", see http://www.blender.org/BL/ ) which has to be
 * bought from the Blender Foundation to become active, in which case the
 * above mentioned GPL option does not apply.
 *
 * The Original Code is Copyright (C) 1997 by Ton Roosendaal, Frank van Beek and Joeri Kassenaar.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL/BL DUAL LICENSE BLOCK *****
 */

/*

 *	togif - 
 *		Convert an IRIS image to GIF format.  Converts b/w and 
 *	color images to 8 bit per pixel GIF format.  Color images
 *	are dithered with a 4 by 4 dither matrix.  GIF image files 
 *	may be uuencoded, and sent over the network.
 *
 *			Paul Haeberli @ Silicon Graphics - 1989
 *
 */
#include <gl/image.h>
#include <math.h>
#include <local/iff.h>

#define GIFGAMMA	(1.5)	/* smaller makes output image darker */

#define MAXXSIZE 8192
#define MAXCOLORS 256

short rbuf[MAXXSIZE];
short gbuf[MAXXSIZE];
short bbuf[MAXXSIZE];
short obuf[MAXXSIZE];
int rmap[MAXCOLORS];
int gmap[MAXCOLORS];
int bmap[MAXCOLORS];

int iscolor, currow;
struct ImBuf * ibuf;

int getgifpix(x,y)
int x, y;
{
	int pix;

	pix = ibuf->rect[(ibuf->x * y) + x];

/*	if(iscolor) {
		if(currow!= y) {
			getrow(iimage,rbuf,iimage->ysize-1-y,0);
			gammawarp(rbuf,1.0/GIFGAMMA,iimage->xsize);
			getrow(iimage,gbuf,iimage->ysize-1-y,1);
			gammawarp(gbuf,1.0/GIFGAMMA,iimage->xsize);
			getrow(iimage,bbuf,iimage->ysize-1-y,2);
			gammawarp(bbuf,1.0/GIFGAMMA,iimage->xsize);
			ditherrow(rbuf,gbuf,bbuf,obuf,iimage->xsize,y);
			currow = y;
		}
		pix = obuf[x];
	} else {
	for (pix = 0; pix < ibuf->y - 1 - y)
		if(currow!= y) {
			getrow(iimage,rbuf,iimage->ysize-1-y,0);
			gammawarp(rbuf,1.0/GIFGAMMA,iimage->xsize);
			ditherrow(rbuf,rbuf,rbuf,obuf,iimage->xsize,y);
			currow = y;
		}
		pix = obuf[x]&0xf;
	}
*/
	return pix;
}

main( argc, argv )
int argc;
char *argv[];
{
	FILE *of;
	int xsize, ysize, col;
	int i, bpp;
	int r, g, b;

	if(argc<3) {
		fprintf(stderr,"usage: togif image.rgb image.gif\n");
		exit(1);
	}
	
	ibuf = loadiffname(argv[1], IB_rect | IB_cmap);
	if (ibuf == 0 | ibuf->cmap == 0 | ibuf->maxcol > 256) {
		exit(0);
	}
	flipy(ibuf);
	xsize = ibuf->x;
	ysize = ibuf->y;
	iscolor = 0;

	of = fopen(argv[2],"w");
	if(!of) {
		fprintf(stderr,"togif: can't open output image [%s]\n",argv[2]);
		exit(1);
	}

	bpp = ibuf->depth;
	for(i=0; i<ibuf->maxcol; i++) {
		col = ibuf->cmap[i];
		rmap[i] = (col & 0xff);
		gmap[i] = ((col >> 8) & 0xff);
		bmap[i] = ((col >> 16) & 0xff);
	}
	
	currow = -1;
	GIFEncode(of,xsize,ysize,0,0,bpp,rmap,gmap,bmap,getgifpix);
	exit(0);
}

/*
 *  	dithering code follows
 *
 *
 */
#define XSIZE	4
#define YSIZE	4
#define TOTAL		(XSIZE*YSIZE)
#define WRAPY(y)	((y)%YSIZE)
#define WRAPX(x)	((x)%XSIZE)

static short dithmat[YSIZE][XSIZE] = {
	0, 8, 2, 10,
	12, 4, 14, 6,
	3, 11, 1, 9,
	15, 7, 13, 5,
};

short **rtab;
short **gtab;
short **btab;

short **makedittab(levels,mult,add)
int levels, mult, add;
{
	register int val;
	register int nshades;
	register int i, j, k;
	register int matval, tabval;
	short **tab;

	nshades = XSIZE*YSIZE*(levels-1)+1;
	tab = (short **)malloc(YSIZE*sizeof(short *));
	for(j=0; j<YSIZE; j++) {
		tab[j] = (short *)malloc(XSIZE*256*sizeof(short));
		for(i=0; i<XSIZE; i++ ) {
			matval = dithmat[i][j];
			for(k=0; k<256; k++) {
				val = (nshades*k)/255;
				if(val==nshades)
					val = nshades-1;
				if((val%TOTAL)>matval)
					tabval =  (val/TOTAL)+1;
				else 
					tabval = (val/TOTAL);
				tabval *= mult;
				tabval += add;
				tab[j][256*i+k] = tabval;
			}
		}
	}
	return tab;
}

ditherrow(r,g,b,wp,n,y)
unsigned short *r, *g, *b;
short *wp;
int n, y;
{
	short *rbase;
	short *gbase;
	short *bbase;

	if(!rtab) {
		if(iscolor) {
			rtab = makedittab(8,1,0);
			gtab = makedittab(8,8,0);
			btab = makedittab(4,64,0);
		} else {
			rtab = makedittab(16,1,0);
			gtab = makedittab(2,16,0);
			btab = makedittab(2,32,0);
		}
	}
	rbase = rtab[WRAPY(y)];
	gbase = gtab[WRAPY(y)];
	bbase = btab[WRAPY(y)];
	while(n) {
		if(n>=XSIZE) {
			*wp++ = rbase[*r++ +   0] + gbase[*g++ +   0] + bbase[*b++ +   0];
			*wp++ = rbase[*r++ + 256] + gbase[*g++ + 256] + bbase[*b++ + 256];
			*wp++ = rbase[*r++ + 512] + gbase[*g++ + 512] + bbase[*b++ + 512];
			*wp++ = rbase[*r++ + 768] + gbase[*g++ + 768] + bbase[*b++ + 768];
			n -= XSIZE;
		} else {
			*wp++ = rbase[*r++] + gbase[*g++] + bbase[*b++];
			rbase += 256;
			gbase += 256;
			bbase += 256;
			n--;
		}
	}
}

/*
 * SCARY GIF code follows . . . . sorry.
 *
 * Based on GIFENCOD by David Rowley <mgardi@watdscu.waterloo.edu>.A
 * Lempel-Zim compression based on "compress".
 *
 */

/*****************************************************************************
 *
 * GIFENCODE.C    - GIF Image compression interface
 *
 * GIFEncode( FName, GHeight, GWidth, GInterlace, Background,
 *            BitsPerPixel, Red, Green, Blue, GetPixel )
 *
 *****************************************************************************/
typedef int (* ifunptr)();

#define TRUE 1
#define FALSE 0

int Width, Height;
int curx, cury;
long CountDown;
int Pass;
int Interlace;
unsigned long cur_accum = 0;
int cur_bits = 0;

/*
 * Bump the 'curx' and 'cury' to point to the next pixel
 */
BumpPixel()
{
	curx++;
	if( curx == Width ) {
		curx = 0;
		if( !Interlace ) {
			cury++;
		} else {
			switch( Pass ) {
			case 0:
				cury += 8;
				if( cury >= Height ) {
					Pass++;
					cury = 4;
				}
				break;
			case 1:
				cury += 8;
				if( cury >= Height ) {
					Pass++;
					cury = 2;
				}
				break;
			case 2:
				cury += 4;
				if( cury >= Height ) {
					Pass++;
					cury = 1;
				}
				break;
			case 3:
				cury += 2;
				break;
			}
		}
	}
}

/*
 * Return the next pixel from the image
 */
GIFNextPixel( getpixel )
ifunptr getpixel;
{
	int r;

	if( CountDown == 0 )
		return EOF;
	CountDown--;
	r = (*getpixel)( curx, cury );
	BumpPixel();
	return r;
}

/*
 * public GIFEncode
 */
GIFEncode( fp, GWidth, GHeight, GInterlace, Background,
BitsPerPixel, Red, Green, Blue, GetPixel )
FILE *fp;
int GWidth, GHeight;
int GInterlace;
int Background;
int BitsPerPixel;
int Red[], Green[], Blue[];
ifunptr GetPixel;
{
	int B;
	int RWidth, RHeight;
	int LeftOfs, TopOfs;
	int Resolution;
	int ColorMapSize;
	int InitCodeSize;
	int i;

	long cur_accum = 0;
	cur_bits = 0;

	Interlace = GInterlace;
	ColorMapSize = 1 << BitsPerPixel;
	RWidth = Width = GWidth;
	RHeight = Height = GHeight;
	LeftOfs = TopOfs = 0;
	Resolution = BitsPerPixel;

	CountDown = (long)Width * (long)Height;
	Pass = 0;
	if( BitsPerPixel <= 1 )
		InitCodeSize = 2;
	else
		InitCodeSize = BitsPerPixel;
	curx = cury = 0;
	fwrite( "GIF87a", 1, 6, fp );
	Putword( RWidth, fp );
	Putword( RHeight, fp );
	B = 0x80;       /* Yes, there is a color map */
	B |= (Resolution - 1) << 5;
	B |= (BitsPerPixel - 1);
	fputc( B, fp );
	fputc( Background, fp );
	fputc( 0, fp );
	for( i=0; i<ColorMapSize; i++ ) {
		fputc( Red[i], fp );
		fputc( Green[i], fp );
		fputc( Blue[i], fp );
	}
	fputc( ',', fp );
	Putword( LeftOfs, fp );
	Putword( TopOfs, fp );
	Putword( Width, fp );
	Putword( Height, fp );
	if( Interlace )
		fputc( 0x40, fp );
	else
		fputc( 0x00, fp );
	fputc( InitCodeSize, fp );
	compress( InitCodeSize+1, fp, GetPixel );
	fputc( 0, fp );
	fputc( ';', fp );
	fclose( fp );
}

/*
 * Write out a word to the GIF file
 */
Putword( w, fp )
int w;
FILE *fp;
{
	fputc( w & 0xff, fp );
	fputc( (w/256) & 0xff, fp );
}


/***************************************************************************
 *
 *  GIFCOMPR.C       - GIF Image compression routines
 *
 *  Lempel-Ziv compression based on 'compress'.  GIF modifications by
 *  David Rowley (mgardi@watdcsu.waterloo.edu)
 *
 ***************************************************************************/

#define CBITS    12
#define HSIZE  5003            /* 80% occupancy */

/*
 * a code_int must be able to hold 2**CBITS values of type int, and also -1
 */
typedef int             code_int;
typedef long int        count_int;
typedef unsigned char  	char_type;

/*
 *
 * GIF Image compression - modified 'compress'
 *
 * Based on: compress.c - File compression ala IEEE Computer, June 1984.
 *
 * By Authors:  Spencer W. Thomas       (decvax!harpo!utah-cs!utah-gr!thomas)
 *              Jim McKie               (decvax!mcvax!jim)
 *              Steve Davies            (decvax!vax135!petsd!peora!srd)
 *              Ken Turkowski           (decvax!decwrl!turtlevax!ken)
 *              James A. Woods          (decvax!ihnp4!ames!jaw)
 *              Joe Orost               (decvax!vax135!petsd!joe)
 *
 */
#include <ctype.h>

#define ARGVAL() (*++(*argv) || (--argc && *++argv))

int n_bits;                        /* number of bits/code */
int maxbits = CBITS;                /* user settable max # bits/code */
code_int maxcode;                  /* maximum code, given n_bits */
code_int maxmaxcode = (code_int)1 << CBITS; /* should NEVER generate this code */
# define MAXCODE(n_bits)        (((code_int) 1 << (n_bits)) - 1)

count_int htab [HSIZE];
unsigned short codetab [HSIZE];
#define HashTabOf(i)       htab[i]
#define CodeTabOf(i)    codetab[i]

code_int hsize = HSIZE;                 /* for dynamic table sizing */

/*
 * To save much memory, we overlay the table used by compress() with those
 * used by decompress().  The tab_prefix table is the same size and type
 * as the codetab.  The tab_suffix table needs 2**CBITS characters.  We
 * get this from the beginning of htab.  The output stack uses the rest
 * of htab, and contains characters.  There is plenty of room for any
 * possible stack (stack used to be 8000 characters).
 */
#define tab_prefixof(i) CodeTabOf(i)
#define tab_suffixof(i)        ((char_type *)(htab))[i]
#define de_stack               ((char_type *)&tab_suffixof((code_int)1<<CBITS))

code_int free_ent = 0;                  /* first unused entry */

/*
 * block compression parameters -- after all codes are used up,
 * and compression rate changes, start over.
 */
int clear_flg = 0;
int offset;
long int in_count = 1;            /* length of input */
long int out_count = 0;           /* # of codes output (for debugging) */

/*
 * compress stdin to stdout
 *
 * Algorithm:  use open addressing double hashing (no chaining) on the
 * prefix code / next character combination.  We do a variant of Knuth's
 * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
 * secondary probe.  Here, the modular division first probe is gives way
 * to a faster exclusive-or manipulation.  Also do block compression with
 * an adaptive reset, whereby the code table is cleared when the compression
 * ratio decreases, but after the table fills.  The variable-length output
 * codes are re-sized at this point, and a special CLEAR code is generated
 * for the decompressor.  Late addition:  construct the table according to
 * file size for noticeable speed improvement on small files.  Please direct
 * questions about this implementation to ames!jaw.
 */

int g_init_bits;
FILE *g_outfile;
int ClearCode;
int EOFCode;

compress( init_bits, outfile, ReadValue )
int init_bits;
FILE *outfile;
ifunptr ReadValue;
{
	register long fcode;
	register code_int i = 0;
	register int c;
	register code_int ent;
	register code_int disp;
	register code_int hsize_reg;
	register int hshift;

	/*
     * Set up the globals:  g_init_bits - initial number of bits
     *                      g_outfile   - pointer to output file
     */
	g_init_bits = init_bits;
	g_outfile = outfile;
	/*
     * Set up the necessary values
     */
	offset = 0;
	out_count = 0;
	clear_flg = 0;
	in_count = 1;
	maxcode = MAXCODE(n_bits = g_init_bits);
	ClearCode = (1 << (init_bits - 1));
	EOFCode = ClearCode + 1;
	free_ent = ClearCode + 2;
	char_init();
	ent = GIFNextPixel( ReadValue );
	hshift = 0;
	for ( fcode = (long) hsize;  fcode < 65536L; fcode *= 2L )
		hshift++;
	hshift = 8 - hshift;                /* set hash code range bound */
	hsize_reg = hsize;
	cl_hash( (count_int) hsize_reg);            /* clear hash table */
	output( (code_int)ClearCode );
	while ( (c = GIFNextPixel( ReadValue )) != EOF ) {
		in_count++;
		fcode = (long) (((long) c << maxbits) + ent);
		/* i = (((code_int)c << hshift) ~ ent);    /* xor hashing */
		i = (((code_int)c << hshift) ^ ent);    /* xor hashing */
		if ( HashTabOf (i) == fcode ) {
			ent = CodeTabOf (i);
			continue;
		} else if ( (long)HashTabOf (i) < 0 )      /* empty slot */
			goto nomatch;
		disp = hsize_reg - i;           /* secondary hash (after G. Knott) */
		if ( i == 0 )
			disp = 1;
probe:
		if ( (i -= disp) < 0 )
			i += hsize_reg;
		if ( HashTabOf (i) == fcode ) {
			ent = CodeTabOf (i);
			continue;
		}
		if ( (long)HashTabOf (i) > 0 )
			goto probe;
nomatch:
		output ( (code_int) ent );
		out_count++;
		ent = c;
		if ( free_ent < maxmaxcode ) {
			CodeTabOf (i) = free_ent++; /* code -> hashtable */
			HashTabOf (i) = fcode;
		} else
			cl_block();
	}
	/*
     * Put out the final code.
     */
	output( (code_int)ent );
	out_count++;
	output( (code_int) EOFCode );
	return;
}

/*****************************************************************
 * TAG( output )
 *
 * Output the given code.
 * Inputs:
 *      code:   A n_bits-bit integer.  If == -1, then EOF.  This assumes
 *              that n_bits =< (long)wordsize - 1.
 * Outputs:
 *      Outputs code to the file.
 * Assumptions:
 *      Chars are 8 bits long.
 * Algorithm:
 *      Maintain a CBITS character long buffer (so that 8 codes will
 * fit in it exactly).  Use the VAX insv instruction to insert each
 * code in turn.  When the buffer fills up empty it and start over.
 */

unsigned long masks[] = { 
	0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
	0x001F, 0x003F, 0x007F, 0x00FF,
	0x01FF, 0x03FF, 0x07FF, 0x0FFF,
	0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };

output( code )
code_int  code;
{
	cur_accum &= masks[ cur_bits ];
	if( cur_bits > 0 )
		cur_accum |= ((long)code << cur_bits);
	else
		cur_accum = code;
	cur_bits += n_bits;
	while( cur_bits >= 8 ) {
		char_out( (unsigned int)(cur_accum & 0xff) );
		cur_accum >>= 8;
		cur_bits -= 8;
	}

	/*
     * If the next entry is going to be too big for the code size,
     * then increase it, if possible.
     */
	if ( free_ent > maxcode || clear_flg ) {
		if( clear_flg ) {
			maxcode = MAXCODE (n_bits = g_init_bits);
			clear_flg = 0;
		} else {
			n_bits++;
			if ( n_bits == maxbits )
				maxcode = maxmaxcode;
			else
				maxcode = MAXCODE(n_bits);
		}
	}
	if( code == EOFCode ) {
		/*
         * At EOF, write the rest of the buffer.
         */
		while( cur_bits > 0 ) {
			char_out( (unsigned int)(cur_accum & 0xff) );
			cur_accum >>= 8;
			cur_bits -= 8;
		}
		flush_char();
		fflush( g_outfile );
		if( ferror( g_outfile ) )
			writeerr();
	}
}

/*
 * Clear out the hash table
 */
cl_block ()             /* table clear for block compress */
{
	cl_hash ( (count_int) hsize );
	free_ent = ClearCode + 2;
	clear_flg = 1;
	output( (code_int)ClearCode );
}

cl_hash(hsize)          /* reset code table */
register count_int hsize;
{
	register count_int *htab_p = htab+hsize;
	register long i;
	register long m1 = -1;

	i = hsize - 16;
	do {                            /* might use Sys V memset(3) here */
		*(htab_p-16) = m1;
		*(htab_p-15) = m1;
		*(htab_p-14) = m1;
		*(htab_p-13) = m1;
		*(htab_p-12) = m1;
		*(htab_p-11) = m1;
		*(htab_p-10) = m1;
		*(htab_p-9) = m1;
		*(htab_p-8) = m1;
		*(htab_p-7) = m1;
		*(htab_p-6) = m1;
		*(htab_p-5) = m1;
		*(htab_p-4) = m1;
		*(htab_p-3) = m1;
		*(htab_p-2) = m1;
		*(htab_p-1) = m1;
		htab_p -= 16;
	} while ((i -= 16) >= 0);
	for ( i += 16; i > 0; i-- )
		*--htab_p = m1;
}

writeerr()
{
	printf( "error writing output file\n" );
	exit(1);
}

/******************************************************************************
 *
 * GIF Specific routines
 *
 ******************************************************************************/

/*
 * Number of characters so far in this 'packet'
 */
int a_count;

/*
 * Set up the 'byte output' routine
 */
char_init()
{
	a_count = 0;
}

/*
 * Define the storage for the packet accumulator
 */
char accum[256];

/*
 * Add a character to the end of the current packet, and if it is 254
 * characters, flush the packet to disk.
 */
char_out( c )
int c;
{
	accum[ a_count++ ] = c;
	if( a_count >= 254 )
		flush_char();
}

/*
 * Flush the packet to disk, and reset the accumulator
 */
flush_char()
{
	if( a_count > 0 ) {
		fputc( a_count, g_outfile );
		fwrite( accum, 1, a_count, g_outfile );
		a_count = 0;
	}
}

static float curgamma;
static short gamtab[256];

gammawarp(sbuf,gam,n)
short *sbuf;
float gam;
int n;
{
	int i;
	float f;

	if(gam!=curgamma) {
		for(i=0; i<256; i++)
			gamtab[i] = 255*pow(i/255.0,gam)+0.5;
		curgamma = gam;
	}
	while(n--) {
		*sbuf = gamtab[*sbuf];
		sbuf++;
	}
}