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/*****
* LZWStream.h : LZW uncompressor public header file
*
* This file Version $Revision: 1.3 $
*
* Creation date: Thu May 8 04:57:06 GMT+0100 1997
* Last modification: $Date: 1997/08/30 00:25:02 $
* By: $Author: newt $
* Current State: $State: Exp $
*
* Author: newt
*
* Copyright (C) 1994-1997 by Ripley Software Development
* All Rights Reserved
*
* This file is part of the XmHTML Widget Library.
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose and without fee is hereby granted, provided
* that the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation. This software is provided "as is" without express or
* implied warranty.
*
* Based on an idea from Derek D. Noonburg <derekn@ece.cmu.edu>, author of
* the public domain xpdf package, a PDF viewer.
*
*****/
/*****
* $Source: /usr/local/rcs/Newt/XmHTML/RCS/LZWStream.h,v $
*****/
/*****
* ChangeLog
* $Log: LZWStream.h,v $
* Revision 1.3 1997/08/30 00:25:02 newt
* Changed copyright. Use of the LZWStream package is now totally unrestricted.
*
* Revision 1.2 1997/08/01 12:52:23 newt
* Progressive image loading changes
*
* Revision 1.1 1997/05/28 01:27:04 newt
* Initial Revision
*
*****/
#ifndef _LZWStream_h_
#define _LZWStream_h_
#define BUFFERSIZE 512
/*****
* LZW stream definition
*****/
typedef struct _LZWStream{
FILE *zPipe; /* uncompress file handle */
FILE *f; /* compress file handle */
char zCmd[256]; /* uncompress command */
char *zName; /* compress file name, indexes in zCmd */
int error; /* uncompress error flag */
int uncompressed; /* uncompress finished flag */
ImageBuffer *ib; /* master input buffer */
unsigned char accum[BUFFERSIZE]; /* buffered output */
int acount; /* current char count */
/* LZW code computation variables */
char buf[280]; /* input buffer */
int curBit; /* no of bits processed so far */
int lastBit; /* bitcount of last bit in input buffer */
int lastByte; /* last known processed byte */
int done; /* input done flag */
int nextCode; /* LZW code counter */
/* global raster data variables */
int codeSize; /* bits per pixel */
int codeBits; /* bits used by each LZW code */
int clearCode; /* reset signal table signal */
int endCode; /* end-of-data signal */
int maxCode; /* start code signal */
int maxCodeSize; /* maximum signal table size */
char outBuf[16]; /* compress output buffer */
/* variables for images with 7 or less bits per pixel */
int offset; /* current bit offset */
int freeEntry; /* compress code counter */
int n_bits; /* output code size */
int maxcode8; /* maximum output signal */
int clearFlag; /* clear signal table flag */
/* data readers */
size_t (*readOK)(ImageBuffer*, unsigned char*, int);
size_t (*getData)(ImageBuffer*, unsigned char*);
char *err_msg; /* error description */
}LZWStream;
/* create a new stream object */
extern LZWStream *LZWStreamCreate(ImageBuffer *ib, char *zCmd);
/*****
* Initialize uncompression. Possible return codes:
* -2: the read functions haven't been set;
* -1: temp file couldn't be opened;
* 0: gif code size is invalid/couldn't be read;
* 1: success.
*****/
extern int LZWStreamInit(LZWStream *lzw);
/* convert GIF LZW to compress LZW */
extern void LZWStreamConvert(LZWStream *lzw);
/* destroy the stream object */
extern void LZWStreamDestroy(LZWStream *lzw);
/* return an allocated buffer with uncompressed stream data */
extern unsigned char *LZWStreamUncompress(LZWStream *lzw, int *size);
/* read uncompressed data from the stream */
extern int LZWStreamFillBuffer(LZWStream *lzw, unsigned char *data, int size);
/* return original bits per pixel */
extern int LZWStreamGetCodeSize(LZWStream *lzw);
/* Don't add anything after this endif! */
#endif /* _LZWStream_h_ */
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