libgphoto2/camlibs/jd11/decomp.c

/*
 * Jenoptik JD11 Camera Driver
 * Copyright © 1999-2001 Marcus Meissner <marcus@jet.franken.de>
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, 
 * but WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details. 
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include "config.h"
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>
#include <unistd.h>

#include "decomp.h"

struct chain { int 	left,val,right; };
struct compstate {
    unsigned char	curmask;
    unsigned char	bytebuf;
    unsigned char	*byteptr;

    struct chain	cl[200];
    int			stackstart;
};

/* FLOAT_QUERY: 0.860000 1.030000 1.150000. */

/********************************************************/
/* The bit stage                                        */
/********************************************************/
static inline int
jd11_getbit(struct compstate *cs) {
    int	ret;
    if (cs->curmask == 0x80)
	cs->bytebuf = *cs->byteptr++;
    ret = cs->curmask & cs->bytebuf;
    cs->curmask >>=1;
    if (!cs->curmask) cs->curmask = 0x80;
    return !!ret;
}

/********************************************************/
/* The huffman compressor stage                         */
/********************************************************/
static int
decomp_1byte(struct compstate *cs) {
    int	xcs = cs->stackstart;
    int	xbit;

    while ((cs->cl[xcs].left>=0) && (cs->cl[xcs].right>=0)) {
	xbit = jd11_getbit(cs); 
	if (xbit)
	    xcs = cs->cl[xcs].left;
	else
	    xcs = cs->cl[xcs].right;
    }
    return cs->cl[xcs].val;
}

static void
build_huffmann_tree(struct compstate *cs) {
	int	xstack[200];
	int	i,curcl=0,curstack=0;
	const int df[] = {
	    -180,180,1000,-90,1000,90,1000,-45,1000,45,1000,-20,1000,
	     20,1000,-11,1000,11,1000,-6,1000,2,1000,6,-2,1000,1000
	};
	for (i=0;i<sizeof(df)/sizeof(df[0]);i++) {
		if (df[i]!=1000) {
			cs->cl[curcl].left = -1;
			cs->cl[curcl].right = -1;
			cs->cl[curcl].val = df[i];
		} else {
			cs->cl[curcl].right	= xstack[--curstack];
			cs->cl[curcl].left	= xstack[--curstack];
		}
		xstack[curstack++] = curcl++;
	}
	cs->stackstart = xstack[0];
}

#define F1	0.5
#define F2	0.0
#define F3	0.5
#define F4	0.0

void
picture_decomp_v1(char *compressed,char *uncompressed,int width,int height) {
	struct	compstate cs;
	unsigned char xbyte;
	int	i=0,curbyte=0,diff,lastval;
	int	*line,*lastline;

	cs.curmask = 0x80; cs.bytebuf = 0; cs.byteptr = compressed;

	build_huffmann_tree(&cs);

	line	= (int*)malloc(sizeof(int)*width);
	lastline= (int*)malloc(sizeof(int)*width);
	curbyte=0;
	memset(line,0,sizeof(line));
	memset(lastline,0,sizeof(line));
	for (i=0;i<width;i++) {
		diff = decomp_1byte(&cs);
		curbyte+=diff;
		xbyte = curbyte;
		if (curbyte>255) xbyte = 255;
		if (curbyte<0) xbyte = 0;

		*uncompressed++=xbyte;

		line[i] = curbyte;
	}
	height--;
	while (height--) {
		lastval = line[0]; /* just before the copy */
		memcpy(lastline,line,width*sizeof(int));
		memset(line,0,width*sizeof(int));
		for (i=0;i<width;i++) {
			diff = decomp_1byte(&cs);
			line[i]=diff+lastval;
			if (i<width-2) {
				lastval = (int)((lastline[i+2]*F4+lastline[i]*F2+lastline[i+1]*F1+line[i]*F3));
			} else {
				if (i==width-2)
					lastval = (int)(lastline[i]*F2+lastline[i+1]*F1+line[i]*F3);
				else
					lastval = line[i];
			}

			xbyte = line[i];
			if (line[i]>255) xbyte = 255;
			if (line[i]<0)	 xbyte = 0;
			*uncompressed++=xbyte;
		}
	}
}

/* Just blow up the picture from 6 bit uncompressed to 8 bit uncompressed */
void
picture_decomp_v2(char *compressed,char *uncompressed,int width,int height) {
	struct	compstate cs;
	int	i,j;
	unsigned char xbyte;

	cs.curmask = 0x80; cs.bytebuf = 0; cs.byteptr = compressed;
	for (i=width*height;i--;) {
		unsigned char xmask = 0x80;
		xbyte = 0;
		for (j=6;j--;) {
			if (jd11_getbit(&cs))
				xbyte|=xmask;
			xmask>>=1;
		}
		*uncompressed++=xbyte;
	}
}