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1079 lines
28 KiB
1079 lines
28 KiB
/* $Id: tif_lzw.c,v 1.1 2005-06-17 13:54:52 vp153 Exp $ */ |
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/* |
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* Copyright (c) 1988-1997 Sam Leffler |
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* Copyright (c) 1991-1997 Silicon Graphics, Inc. |
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* |
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* Permission to use, copy, modify, distribute, and sell this software and |
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* its documentation for any purpose is hereby granted without fee, provided |
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* that (i) the above copyright notices and this permission notice appear in |
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* all copies of the software and related documentation, and (ii) the names of |
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* Sam Leffler and Silicon Graphics may not be used in any advertising or |
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* publicity relating to the software without the specific, prior written |
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* permission of Sam Leffler and Silicon Graphics. |
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* |
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* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, |
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* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY |
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* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. |
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* |
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* IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR |
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* ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, |
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* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, |
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* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF |
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* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE |
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* OF THIS SOFTWARE. |
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*/ |
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#include "tiffiop.h" |
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#ifdef LZW_SUPPORT |
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/* |
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* TIFF Library. |
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* Rev 5.0 Lempel-Ziv & Welch Compression Support |
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* |
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* This code is derived from the compress program whose code is |
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* derived from software contributed to Berkeley by James A. Woods, |
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* derived from original work by Spencer Thomas and Joseph Orost. |
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* |
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* The original Berkeley copyright notice appears below in its entirety. |
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*/ |
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#include "tif_predict.h" |
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#include <stdio.h> |
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/* |
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* NB: The 5.0 spec describes a different algorithm than Aldus |
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* implements. Specifically, Aldus does code length transitions |
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* one code earlier than should be done (for real LZW). |
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* Earlier versions of this library implemented the correct |
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* LZW algorithm, but emitted codes in a bit order opposite |
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* to the TIFF spec. Thus, to maintain compatibility w/ Aldus |
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* we interpret MSB-LSB ordered codes to be images written w/ |
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* old versions of this library, but otherwise adhere to the |
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* Aldus "off by one" algorithm. |
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* |
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* Future revisions to the TIFF spec are expected to "clarify this issue". |
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*/ |
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#define LZW_COMPAT /* include backwards compatibility code */ |
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/* |
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* Each strip of data is supposed to be terminated by a CODE_EOI. |
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* If the following #define is included, the decoder will also |
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* check for end-of-strip w/o seeing this code. This makes the |
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* library more robust, but also slower. |
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*/ |
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#define LZW_CHECKEOS /* include checks for strips w/o EOI code */ |
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#define MAXCODE(n) ((1L<<(n))-1) |
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/* |
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* The TIFF spec specifies that encoded bit |
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* strings range from 9 to 12 bits. |
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*/ |
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#define BITS_MIN 9 /* start with 9 bits */ |
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#define BITS_MAX 12 /* max of 12 bit strings */ |
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/* predefined codes */ |
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#define CODE_CLEAR 256 /* code to clear string table */ |
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#define CODE_EOI 257 /* end-of-information code */ |
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#define CODE_FIRST 258 /* first free code entry */ |
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#define CODE_MAX MAXCODE(BITS_MAX) |
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#define HSIZE 9001L /* 91% occupancy */ |
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#define HSHIFT (13-8) |
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#ifdef LZW_COMPAT |
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/* NB: +1024 is for compatibility with old files */ |
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#define CSIZE (MAXCODE(BITS_MAX)+1024L) |
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#else |
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#define CSIZE (MAXCODE(BITS_MAX)+1L) |
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#endif |
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/* |
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* State block for each open TIFF file using LZW |
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* compression/decompression. Note that the predictor |
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* state block must be first in this data structure. |
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*/ |
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typedef struct { |
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TIFFPredictorState predict; /* predictor super class */ |
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unsigned short nbits; /* # of bits/code */ |
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unsigned short maxcode; /* maximum code for lzw_nbits */ |
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unsigned short free_ent; /* next free entry in hash table */ |
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long nextdata; /* next bits of i/o */ |
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long nextbits; /* # of valid bits in lzw_nextdata */ |
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int rw_mode; /* preserve rw_mode from init */ |
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} LZWBaseState; |
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#define lzw_nbits base.nbits |
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#define lzw_maxcode base.maxcode |
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#define lzw_free_ent base.free_ent |
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#define lzw_nextdata base.nextdata |
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#define lzw_nextbits base.nextbits |
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/* |
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* Encoding-specific state. |
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*/ |
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typedef uint16 hcode_t; /* codes fit in 16 bits */ |
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typedef struct { |
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long hash; |
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hcode_t code; |
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} hash_t; |
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/* |
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* Decoding-specific state. |
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*/ |
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typedef struct code_ent { |
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struct code_ent *next; |
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unsigned short length; /* string len, including this token */ |
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unsigned char value; /* data value */ |
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unsigned char firstchar; /* first token of string */ |
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} code_t; |
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typedef int (*decodeFunc)(TIFF*, tidata_t, tsize_t, tsample_t); |
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typedef struct { |
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LZWBaseState base; |
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/* Decoding specific data */ |
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long dec_nbitsmask; /* lzw_nbits 1 bits, right adjusted */ |
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long dec_restart; /* restart count */ |
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#ifdef LZW_CHECKEOS |
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long dec_bitsleft; /* available bits in raw data */ |
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#endif |
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decodeFunc dec_decode; /* regular or backwards compatible */ |
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code_t* dec_codep; /* current recognized code */ |
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code_t* dec_oldcodep; /* previously recognized code */ |
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code_t* dec_free_entp; /* next free entry */ |
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code_t* dec_maxcodep; /* max available entry */ |
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code_t* dec_codetab; /* kept separate for small machines */ |
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/* Encoding specific data */ |
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int enc_oldcode; /* last code encountered */ |
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long enc_checkpoint; /* point at which to clear table */ |
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#define CHECK_GAP 10000 /* enc_ratio check interval */ |
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long enc_ratio; /* current compression ratio */ |
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long enc_incount; /* (input) data bytes encoded */ |
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long enc_outcount; /* encoded (output) bytes */ |
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tidata_t enc_rawlimit; /* bound on tif_rawdata buffer */ |
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hash_t* enc_hashtab; /* kept separate for small machines */ |
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} LZWCodecState; |
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#define LZWState(tif) ((LZWBaseState*) (tif)->tif_data) |
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#define DecoderState(tif) ((LZWCodecState*) LZWState(tif)) |
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#define EncoderState(tif) ((LZWCodecState*) LZWState(tif)) |
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static int LZWDecode(TIFF*, tidata_t, tsize_t, tsample_t); |
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#ifdef LZW_COMPAT |
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static int LZWDecodeCompat(TIFF*, tidata_t, tsize_t, tsample_t); |
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#endif |
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static void cl_hash(LZWCodecState*); |
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/* |
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* LZW Decoder. |
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*/ |
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#ifdef LZW_CHECKEOS |
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/* |
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* This check shouldn't be necessary because each |
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* strip is suppose to be terminated with CODE_EOI. |
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*/ |
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#define NextCode(_tif, _sp, _bp, _code, _get) { \ |
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if ((_sp)->dec_bitsleft < nbits) { \ |
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TIFFWarning(_tif->tif_name, \ |
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"LZWDecode: Strip %d not terminated with EOI code", \ |
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_tif->tif_curstrip); \ |
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_code = CODE_EOI; \ |
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} else { \ |
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_get(_sp,_bp,_code); \ |
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(_sp)->dec_bitsleft -= nbits; \ |
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} \ |
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} |
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#else |
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#define NextCode(tif, sp, bp, code, get) get(sp, bp, code) |
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#endif |
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static int |
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LZWSetupDecode(TIFF* tif) |
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{ |
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LZWCodecState* sp = DecoderState(tif); |
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static const char module[] = " LZWSetupDecode"; |
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int code; |
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if( sp == NULL ) |
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{ |
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/* |
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* Allocate state block so tag methods have storage to record |
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* values. |
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*/ |
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tif->tif_data = (tidata_t) _TIFFmalloc(sizeof(LZWCodecState)); |
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if (tif->tif_data == NULL) |
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{ |
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TIFFError("LZWPreDecode", "No space for LZW state block"); |
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return (0); |
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} |
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DecoderState(tif)->dec_codetab = NULL; |
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DecoderState(tif)->dec_decode = NULL; |
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/* |
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* Setup predictor setup. |
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*/ |
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(void) TIFFPredictorInit(tif); |
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sp = DecoderState(tif); |
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} |
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assert(sp != NULL); |
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if (sp->dec_codetab == NULL) { |
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sp->dec_codetab = (code_t*)_TIFFmalloc(CSIZE*sizeof (code_t)); |
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if (sp->dec_codetab == NULL) { |
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TIFFError(module, "No space for LZW code table"); |
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return (0); |
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} |
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/* |
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* Pre-load the table. |
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*/ |
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code = 255; |
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do { |
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sp->dec_codetab[code].value = code; |
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sp->dec_codetab[code].firstchar = code; |
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sp->dec_codetab[code].length = 1; |
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sp->dec_codetab[code].next = NULL; |
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} while (code--); |
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} |
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return (1); |
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} |
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/* |
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* Setup state for decoding a strip. |
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*/ |
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static int |
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LZWPreDecode(TIFF* tif, tsample_t s) |
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{ |
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LZWCodecState *sp = DecoderState(tif); |
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(void) s; |
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assert(sp != NULL); |
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/* |
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* Check for old bit-reversed codes. |
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*/ |
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if (tif->tif_rawdata[0] == 0 && (tif->tif_rawdata[1] & 0x1)) { |
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#ifdef LZW_COMPAT |
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if (!sp->dec_decode) { |
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TIFFWarning(tif->tif_name, |
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"Old-style LZW codes, convert file"); |
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/* |
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* Override default decoding methods with |
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* ones that deal with the old coding. |
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* Otherwise the predictor versions set |
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* above will call the compatibility routines |
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* through the dec_decode method. |
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*/ |
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tif->tif_decoderow = LZWDecodeCompat; |
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tif->tif_decodestrip = LZWDecodeCompat; |
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tif->tif_decodetile = LZWDecodeCompat; |
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/* |
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* If doing horizontal differencing, must |
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* re-setup the predictor logic since we |
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* switched the basic decoder methods... |
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*/ |
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(*tif->tif_setupdecode)(tif); |
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sp->dec_decode = LZWDecodeCompat; |
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} |
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sp->lzw_maxcode = MAXCODE(BITS_MIN); |
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#else /* !LZW_COMPAT */ |
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if (!sp->dec_decode) { |
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TIFFError(tif->tif_name, |
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"Old-style LZW codes not supported"); |
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sp->dec_decode = LZWDecode; |
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} |
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return (0); |
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#endif/* !LZW_COMPAT */ |
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} else { |
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sp->lzw_maxcode = MAXCODE(BITS_MIN)-1; |
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sp->dec_decode = LZWDecode; |
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} |
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sp->lzw_nbits = BITS_MIN; |
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sp->lzw_nextbits = 0; |
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sp->lzw_nextdata = 0; |
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sp->dec_restart = 0; |
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sp->dec_nbitsmask = MAXCODE(BITS_MIN); |
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#ifdef LZW_CHECKEOS |
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sp->dec_bitsleft = tif->tif_rawcc << 3; |
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#endif |
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sp->dec_free_entp = sp->dec_codetab + CODE_FIRST; |
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/* |
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* Zero entries that are not yet filled in. We do |
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* this to guard against bogus input data that causes |
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* us to index into undefined entries. If you can |
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* come up with a way to safely bounds-check input codes |
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* while decoding then you can remove this operation. |
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*/ |
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_TIFFmemset(sp->dec_free_entp, 0, (CSIZE-CODE_FIRST)*sizeof (code_t)); |
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sp->dec_oldcodep = &sp->dec_codetab[-1]; |
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sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask-1]; |
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return (1); |
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} |
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/* |
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* Decode a "hunk of data". |
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*/ |
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#define GetNextCode(sp, bp, code) { \ |
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nextdata = (nextdata<<8) | *(bp)++; \ |
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nextbits += 8; \ |
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if (nextbits < nbits) { \ |
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nextdata = (nextdata<<8) | *(bp)++; \ |
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nextbits += 8; \ |
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} \ |
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code = (hcode_t)((nextdata >> (nextbits-nbits)) & nbitsmask); \ |
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nextbits -= nbits; \ |
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} |
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static void |
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codeLoop(TIFF* tif) |
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{ |
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TIFFError(tif->tif_name, |
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"LZWDecode: Bogus encoding, loop in the code table; scanline %d", |
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tif->tif_row); |
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} |
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static int |
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LZWDecode(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s) |
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{ |
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LZWCodecState *sp = DecoderState(tif); |
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char *op = (char*) op0; |
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long occ = (long) occ0; |
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char *tp; |
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unsigned char *bp; |
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hcode_t code; |
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int len; |
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long nbits, nextbits, nextdata, nbitsmask; |
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code_t *codep, *free_entp, *maxcodep, *oldcodep; |
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(void) s; |
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assert(sp != NULL); |
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/* |
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* Restart interrupted output operation. |
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*/ |
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if (sp->dec_restart) { |
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long residue; |
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codep = sp->dec_codep; |
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residue = codep->length - sp->dec_restart; |
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if (residue > occ) { |
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/* |
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* Residue from previous decode is sufficient |
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* to satisfy decode request. Skip to the |
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* start of the decoded string, place decoded |
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* values in the output buffer, and return. |
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*/ |
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sp->dec_restart += occ; |
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do { |
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codep = codep->next; |
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} while (--residue > occ && codep); |
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if (codep) { |
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tp = op + occ; |
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do { |
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*--tp = codep->value; |
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codep = codep->next; |
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} while (--occ && codep); |
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} |
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return (1); |
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} |
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/* |
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* Residue satisfies only part of the decode request. |
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*/ |
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op += residue, occ -= residue; |
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tp = op; |
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do { |
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int t; |
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--tp; |
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t = codep->value; |
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codep = codep->next; |
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*tp = t; |
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} while (--residue && codep); |
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sp->dec_restart = 0; |
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} |
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bp = (unsigned char *)tif->tif_rawcp; |
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nbits = sp->lzw_nbits; |
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nextdata = sp->lzw_nextdata; |
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nextbits = sp->lzw_nextbits; |
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nbitsmask = sp->dec_nbitsmask; |
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oldcodep = sp->dec_oldcodep; |
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free_entp = sp->dec_free_entp; |
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maxcodep = sp->dec_maxcodep; |
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while (occ > 0) { |
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NextCode(tif, sp, bp, code, GetNextCode); |
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if (code == CODE_EOI) |
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break; |
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if (code == CODE_CLEAR) { |
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free_entp = sp->dec_codetab + CODE_FIRST; |
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nbits = BITS_MIN; |
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nbitsmask = MAXCODE(BITS_MIN); |
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maxcodep = sp->dec_codetab + nbitsmask-1; |
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NextCode(tif, sp, bp, code, GetNextCode); |
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if (code == CODE_EOI) |
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break; |
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*op++ = (char)code, occ--; |
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oldcodep = sp->dec_codetab + code; |
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continue; |
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} |
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codep = sp->dec_codetab + code; |
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/* |
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* Add the new entry to the code table. |
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*/ |
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if (free_entp < &sp->dec_codetab[0] || |
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free_entp >= &sp->dec_codetab[CSIZE]) { |
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TIFFError(tif->tif_name, |
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"LZWDecode: Corrupted LZW table at scanline %d", |
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tif->tif_row); |
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return (0); |
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} |
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free_entp->next = oldcodep; |
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if (free_entp->next < &sp->dec_codetab[0] || |
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free_entp->next >= &sp->dec_codetab[CSIZE]) { |
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TIFFError(tif->tif_name, |
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"LZWDecode: Corrupted LZW table at scanline %d", |
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tif->tif_row); |
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return (0); |
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} |
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free_entp->firstchar = free_entp->next->firstchar; |
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free_entp->length = free_entp->next->length+1; |
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free_entp->value = (codep < free_entp) ? |
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codep->firstchar : free_entp->firstchar; |
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if (++free_entp > maxcodep) { |
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if (++nbits > BITS_MAX) /* should not happen */ |
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nbits = BITS_MAX; |
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nbitsmask = MAXCODE(nbits); |
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maxcodep = sp->dec_codetab + nbitsmask-1; |
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} |
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oldcodep = codep; |
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if (code >= 256) { |
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/* |
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* Code maps to a string, copy string |
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* value to output (written in reverse). |
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*/ |
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if(codep->length == 0) { |
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TIFFError(tif->tif_name, |
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"LZWDecode: Wrong length of decoded string: " |
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"data probably corrupted at scanline %d", |
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tif->tif_row); |
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return (0); |
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} |
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if (codep->length > occ) { |
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/* |
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* String is too long for decode buffer, |
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* locate portion that will fit, copy to |
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* the decode buffer, and setup restart |
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* logic for the next decoding call. |
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*/ |
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sp->dec_codep = codep; |
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do { |
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codep = codep->next; |
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} while (codep && codep->length > occ); |
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if (codep) { |
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sp->dec_restart = occ; |
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tp = op + occ; |
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do { |
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*--tp = codep->value; |
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codep = codep->next; |
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} while (--occ && codep); |
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if (codep) |
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codeLoop(tif); |
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} |
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break; |
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} |
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len = codep->length; |
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tp = op + len; |
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do { |
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int t; |
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--tp; |
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t = codep->value; |
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codep = codep->next; |
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*tp = t; |
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} while (codep && tp > op); |
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if (codep) { |
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codeLoop(tif); |
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break; |
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} |
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op += len, occ -= len; |
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} else |
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*op++ = (char)code, occ--; |
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} |
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|
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tif->tif_rawcp = (tidata_t) bp; |
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sp->lzw_nbits = (unsigned short) nbits; |
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sp->lzw_nextdata = nextdata; |
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sp->lzw_nextbits = nextbits; |
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sp->dec_nbitsmask = nbitsmask; |
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sp->dec_oldcodep = oldcodep; |
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sp->dec_free_entp = free_entp; |
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sp->dec_maxcodep = maxcodep; |
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|
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if (occ > 0) { |
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TIFFError(tif->tif_name, |
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"LZWDecode: Not enough data at scanline %d (short %d bytes)", |
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tif->tif_row, occ); |
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return (0); |
|
} |
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return (1); |
|
} |
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|
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#ifdef LZW_COMPAT |
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/* |
|
* Decode a "hunk of data" for old images. |
|
*/ |
|
#define GetNextCodeCompat(sp, bp, code) { \ |
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nextdata |= (unsigned long) *(bp)++ << nextbits; \ |
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nextbits += 8; \ |
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if (nextbits < nbits) { \ |
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nextdata |= (unsigned long) *(bp)++ << nextbits;\ |
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nextbits += 8; \ |
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} \ |
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code = (hcode_t)(nextdata & nbitsmask); \ |
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nextdata >>= nbits; \ |
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nextbits -= nbits; \ |
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} |
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|
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static int |
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LZWDecodeCompat(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s) |
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{ |
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LZWCodecState *sp = DecoderState(tif); |
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char *op = (char*) op0; |
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long occ = (long) occ0; |
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char *tp; |
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unsigned char *bp; |
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int code, nbits; |
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long nextbits, nextdata, nbitsmask; |
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code_t *codep, *free_entp, *maxcodep, *oldcodep; |
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|
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(void) s; |
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assert(sp != NULL); |
|
/* |
|
* Restart interrupted output operation. |
|
*/ |
|
if (sp->dec_restart) { |
|
long residue; |
|
|
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codep = sp->dec_codep; |
|
residue = codep->length - sp->dec_restart; |
|
if (residue > occ) { |
|
/* |
|
* Residue from previous decode is sufficient |
|
* to satisfy decode request. Skip to the |
|
* start of the decoded string, place decoded |
|
* values in the output buffer, and return. |
|
*/ |
|
sp->dec_restart += occ; |
|
do { |
|
codep = codep->next; |
|
} while (--residue > occ); |
|
tp = op + occ; |
|
do { |
|
*--tp = codep->value; |
|
codep = codep->next; |
|
} while (--occ); |
|
return (1); |
|
} |
|
/* |
|
* Residue satisfies only part of the decode request. |
|
*/ |
|
op += residue, occ -= residue; |
|
tp = op; |
|
do { |
|
*--tp = codep->value; |
|
codep = codep->next; |
|
} while (--residue); |
|
sp->dec_restart = 0; |
|
} |
|
|
|
bp = (unsigned char *)tif->tif_rawcp; |
|
nbits = sp->lzw_nbits; |
|
nextdata = sp->lzw_nextdata; |
|
nextbits = sp->lzw_nextbits; |
|
nbitsmask = sp->dec_nbitsmask; |
|
oldcodep = sp->dec_oldcodep; |
|
free_entp = sp->dec_free_entp; |
|
maxcodep = sp->dec_maxcodep; |
|
|
|
while (occ > 0) { |
|
NextCode(tif, sp, bp, code, GetNextCodeCompat); |
|
if (code == CODE_EOI) |
|
break; |
|
if (code == CODE_CLEAR) { |
|
free_entp = sp->dec_codetab + CODE_FIRST; |
|
nbits = BITS_MIN; |
|
nbitsmask = MAXCODE(BITS_MIN); |
|
maxcodep = sp->dec_codetab + nbitsmask; |
|
NextCode(tif, sp, bp, code, GetNextCodeCompat); |
|
if (code == CODE_EOI) |
|
break; |
|
*op++ = code, occ--; |
|
oldcodep = sp->dec_codetab + code; |
|
continue; |
|
} |
|
codep = sp->dec_codetab + code; |
|
|
|
/* |
|
* Add the new entry to the code table. |
|
*/ |
|
if (free_entp < &sp->dec_codetab[0] || |
|
free_entp >= &sp->dec_codetab[CSIZE]) { |
|
TIFFError(tif->tif_name, |
|
"LZWDecodeCompat: Corrupted LZW table at scanline %d", |
|
tif->tif_row); |
|
return (0); |
|
} |
|
|
|
free_entp->next = oldcodep; |
|
if (free_entp->next < &sp->dec_codetab[0] || |
|
free_entp->next >= &sp->dec_codetab[CSIZE]) { |
|
TIFFError(tif->tif_name, |
|
"LZWDecodeCompat: Corrupted LZW table at scanline %d", |
|
tif->tif_row); |
|
return (0); |
|
} |
|
free_entp->firstchar = free_entp->next->firstchar; |
|
free_entp->length = free_entp->next->length+1; |
|
free_entp->value = (codep < free_entp) ? |
|
codep->firstchar : free_entp->firstchar; |
|
if (++free_entp > maxcodep) { |
|
if (++nbits > BITS_MAX) /* should not happen */ |
|
nbits = BITS_MAX; |
|
nbitsmask = MAXCODE(nbits); |
|
maxcodep = sp->dec_codetab + nbitsmask; |
|
} |
|
oldcodep = codep; |
|
if (code >= 256) { |
|
/* |
|
* Code maps to a string, copy string |
|
* value to output (written in reverse). |
|
*/ |
|
if(codep->length == 0) { |
|
TIFFError(tif->tif_name, |
|
"LZWDecodeCompat: Wrong length of decoded " |
|
"string: data probably corrupted at scanline %d", |
|
tif->tif_row); |
|
return (0); |
|
} |
|
if (codep->length > occ) { |
|
/* |
|
* String is too long for decode buffer, |
|
* locate portion that will fit, copy to |
|
* the decode buffer, and setup restart |
|
* logic for the next decoding call. |
|
*/ |
|
sp->dec_codep = codep; |
|
do { |
|
codep = codep->next; |
|
} while (codep->length > occ); |
|
sp->dec_restart = occ; |
|
tp = op + occ; |
|
do { |
|
*--tp = codep->value; |
|
codep = codep->next; |
|
} while (--occ); |
|
break; |
|
} |
|
op += codep->length, occ -= codep->length; |
|
tp = op; |
|
do { |
|
*--tp = codep->value; |
|
} while( (codep = codep->next) != NULL); |
|
} else |
|
*op++ = code, occ--; |
|
} |
|
|
|
tif->tif_rawcp = (tidata_t) bp; |
|
sp->lzw_nbits = nbits; |
|
sp->lzw_nextdata = nextdata; |
|
sp->lzw_nextbits = nextbits; |
|
sp->dec_nbitsmask = nbitsmask; |
|
sp->dec_oldcodep = oldcodep; |
|
sp->dec_free_entp = free_entp; |
|
sp->dec_maxcodep = maxcodep; |
|
|
|
if (occ > 0) { |
|
TIFFError(tif->tif_name, |
|
"LZWDecodeCompat: Not enough data at scanline %d (short %d bytes)", |
|
tif->tif_row, occ); |
|
return (0); |
|
} |
|
return (1); |
|
} |
|
#endif /* LZW_COMPAT */ |
|
|
|
/* |
|
* LZW Encoding. |
|
*/ |
|
|
|
static int |
|
LZWSetupEncode(TIFF* tif) |
|
{ |
|
LZWCodecState* sp = EncoderState(tif); |
|
static const char module[] = "LZWSetupEncode"; |
|
|
|
assert(sp != NULL); |
|
sp->enc_hashtab = (hash_t*) _TIFFmalloc(HSIZE*sizeof (hash_t)); |
|
if (sp->enc_hashtab == NULL) { |
|
TIFFError(module, "No space for LZW hash table"); |
|
return (0); |
|
} |
|
return (1); |
|
} |
|
|
|
/* |
|
* Reset encoding state at the start of a strip. |
|
*/ |
|
static int |
|
LZWPreEncode(TIFF* tif, tsample_t s) |
|
{ |
|
LZWCodecState *sp = EncoderState(tif); |
|
|
|
(void) s; |
|
assert(sp != NULL); |
|
sp->lzw_nbits = BITS_MIN; |
|
sp->lzw_maxcode = MAXCODE(BITS_MIN); |
|
sp->lzw_free_ent = CODE_FIRST; |
|
sp->lzw_nextbits = 0; |
|
sp->lzw_nextdata = 0; |
|
sp->enc_checkpoint = CHECK_GAP; |
|
sp->enc_ratio = 0; |
|
sp->enc_incount = 0; |
|
sp->enc_outcount = 0; |
|
/* |
|
* The 4 here insures there is space for 2 max-sized |
|
* codes in LZWEncode and LZWPostDecode. |
|
*/ |
|
sp->enc_rawlimit = tif->tif_rawdata + tif->tif_rawdatasize-1 - 4; |
|
cl_hash(sp); /* clear hash table */ |
|
sp->enc_oldcode = (hcode_t) -1; /* generates CODE_CLEAR in LZWEncode */ |
|
return (1); |
|
} |
|
|
|
#define CALCRATIO(sp, rat) { \ |
|
if (incount > 0x007fffff) { /* NB: shift will overflow */\ |
|
rat = outcount >> 8; \ |
|
rat = (rat == 0 ? 0x7fffffff : incount/rat); \ |
|
} else \ |
|
rat = (incount<<8) / outcount; \ |
|
} |
|
#define PutNextCode(op, c) { \ |
|
nextdata = (nextdata << nbits) | c; \ |
|
nextbits += nbits; \ |
|
*op++ = (unsigned char)(nextdata >> (nextbits-8)); \ |
|
nextbits -= 8; \ |
|
if (nextbits >= 8) { \ |
|
*op++ = (unsigned char)(nextdata >> (nextbits-8)); \ |
|
nextbits -= 8; \ |
|
} \ |
|
outcount += nbits; \ |
|
} |
|
|
|
/* |
|
* Encode a chunk of pixels. |
|
* |
|
* Uses an 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 CODE_CLEAR is generated |
|
* for the decoder. |
|
*/ |
|
static int |
|
LZWEncode(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s) |
|
{ |
|
register LZWCodecState *sp = EncoderState(tif); |
|
register long fcode; |
|
register hash_t *hp; |
|
register int h, c; |
|
hcode_t ent; |
|
long disp; |
|
long incount, outcount, checkpoint; |
|
long nextdata, nextbits; |
|
int free_ent, maxcode, nbits; |
|
tidata_t op, limit; |
|
|
|
(void) s; |
|
if (sp == NULL) |
|
return (0); |
|
/* |
|
* Load local state. |
|
*/ |
|
incount = sp->enc_incount; |
|
outcount = sp->enc_outcount; |
|
checkpoint = sp->enc_checkpoint; |
|
nextdata = sp->lzw_nextdata; |
|
nextbits = sp->lzw_nextbits; |
|
free_ent = sp->lzw_free_ent; |
|
maxcode = sp->lzw_maxcode; |
|
nbits = sp->lzw_nbits; |
|
op = tif->tif_rawcp; |
|
limit = sp->enc_rawlimit; |
|
ent = sp->enc_oldcode; |
|
|
|
if (ent == (hcode_t) -1 && cc > 0) { |
|
/* |
|
* NB: This is safe because it can only happen |
|
* at the start of a strip where we know there |
|
* is space in the data buffer. |
|
*/ |
|
PutNextCode(op, CODE_CLEAR); |
|
ent = *bp++; cc--; incount++; |
|
} |
|
while (cc > 0) { |
|
c = *bp++; cc--; incount++; |
|
fcode = ((long)c << BITS_MAX) + ent; |
|
h = (c << HSHIFT) ^ ent; /* xor hashing */ |
|
#ifdef _WINDOWS |
|
/* |
|
* Check hash index for an overflow. |
|
*/ |
|
if (h >= HSIZE) |
|
h -= HSIZE; |
|
#endif |
|
hp = &sp->enc_hashtab[h]; |
|
if (hp->hash == fcode) { |
|
ent = hp->code; |
|
continue; |
|
} |
|
if (hp->hash >= 0) { |
|
/* |
|
* Primary hash failed, check secondary hash. |
|
*/ |
|
disp = HSIZE - h; |
|
if (h == 0) |
|
disp = 1; |
|
do { |
|
/* |
|
* Avoid pointer arithmetic 'cuz of |
|
* wraparound problems with segments. |
|
*/ |
|
if ((h -= disp) < 0) |
|
h += HSIZE; |
|
hp = &sp->enc_hashtab[h]; |
|
if (hp->hash == fcode) { |
|
ent = hp->code; |
|
goto hit; |
|
} |
|
} while (hp->hash >= 0); |
|
} |
|
/* |
|
* New entry, emit code and add to table. |
|
*/ |
|
/* |
|
* Verify there is space in the buffer for the code |
|
* and any potential Clear code that might be emitted |
|
* below. The value of limit is setup so that there |
|
* are at least 4 bytes free--room for 2 codes. |
|
*/ |
|
if (op > limit) { |
|
tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata); |
|
TIFFFlushData1(tif); |
|
op = tif->tif_rawdata; |
|
} |
|
PutNextCode(op, ent); |
|
ent = c; |
|
hp->code = free_ent++; |
|
hp->hash = fcode; |
|
if (free_ent == CODE_MAX-1) { |
|
/* table is full, emit clear code and reset */ |
|
cl_hash(sp); |
|
sp->enc_ratio = 0; |
|
incount = 0; |
|
outcount = 0; |
|
free_ent = CODE_FIRST; |
|
PutNextCode(op, CODE_CLEAR); |
|
nbits = BITS_MIN; |
|
maxcode = MAXCODE(BITS_MIN); |
|
} else { |
|
/* |
|
* If the next entry is going to be too big for |
|
* the code size, then increase it, if possible. |
|
*/ |
|
if (free_ent > maxcode) { |
|
nbits++; |
|
assert(nbits <= BITS_MAX); |
|
maxcode = (int) MAXCODE(nbits); |
|
} else if (incount >= checkpoint) { |
|
long rat; |
|
/* |
|
* Check compression ratio and, if things seem |
|
* to be slipping, clear the hash table and |
|
* reset state. The compression ratio is a |
|
* 24+8-bit fractional number. |
|
*/ |
|
checkpoint = incount+CHECK_GAP; |
|
CALCRATIO(sp, rat); |
|
if (rat <= sp->enc_ratio) { |
|
cl_hash(sp); |
|
sp->enc_ratio = 0; |
|
incount = 0; |
|
outcount = 0; |
|
free_ent = CODE_FIRST; |
|
PutNextCode(op, CODE_CLEAR); |
|
nbits = BITS_MIN; |
|
maxcode = MAXCODE(BITS_MIN); |
|
} else |
|
sp->enc_ratio = rat; |
|
} |
|
} |
|
hit: |
|
; |
|
} |
|
|
|
/* |
|
* Restore global state. |
|
*/ |
|
sp->enc_incount = incount; |
|
sp->enc_outcount = outcount; |
|
sp->enc_checkpoint = checkpoint; |
|
sp->enc_oldcode = ent; |
|
sp->lzw_nextdata = nextdata; |
|
sp->lzw_nextbits = nextbits; |
|
sp->lzw_free_ent = free_ent; |
|
sp->lzw_maxcode = maxcode; |
|
sp->lzw_nbits = nbits; |
|
tif->tif_rawcp = op; |
|
return (1); |
|
} |
|
|
|
/* |
|
* Finish off an encoded strip by flushing the last |
|
* string and tacking on an End Of Information code. |
|
*/ |
|
static int |
|
LZWPostEncode(TIFF* tif) |
|
{ |
|
register LZWCodecState *sp = EncoderState(tif); |
|
tidata_t op = tif->tif_rawcp; |
|
long nextbits = sp->lzw_nextbits; |
|
long nextdata = sp->lzw_nextdata; |
|
long outcount = sp->enc_outcount; |
|
int nbits = sp->lzw_nbits; |
|
|
|
if (op > sp->enc_rawlimit) { |
|
tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata); |
|
TIFFFlushData1(tif); |
|
op = tif->tif_rawdata; |
|
} |
|
if (sp->enc_oldcode != (hcode_t) -1) { |
|
PutNextCode(op, sp->enc_oldcode); |
|
sp->enc_oldcode = (hcode_t) -1; |
|
} |
|
PutNextCode(op, CODE_EOI); |
|
if (nextbits > 0) |
|
*op++ = (unsigned char)(nextdata << (8-nextbits)); |
|
tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata); |
|
return (1); |
|
} |
|
|
|
/* |
|
* Reset encoding hash table. |
|
*/ |
|
static void |
|
cl_hash(LZWCodecState* sp) |
|
{ |
|
register hash_t *hp = &sp->enc_hashtab[HSIZE-1]; |
|
register long i = HSIZE-8; |
|
|
|
do { |
|
i -= 8; |
|
hp[-7].hash = -1; |
|
hp[-6].hash = -1; |
|
hp[-5].hash = -1; |
|
hp[-4].hash = -1; |
|
hp[-3].hash = -1; |
|
hp[-2].hash = -1; |
|
hp[-1].hash = -1; |
|
hp[ 0].hash = -1; |
|
hp -= 8; |
|
} while (i >= 0); |
|
for (i += 8; i > 0; i--, hp--) |
|
hp->hash = -1; |
|
} |
|
|
|
static void |
|
LZWCleanup(TIFF* tif) |
|
{ |
|
if (tif->tif_data) { |
|
if (DecoderState(tif)->dec_codetab) |
|
_TIFFfree(DecoderState(tif)->dec_codetab); |
|
|
|
if (EncoderState(tif)->enc_hashtab) |
|
_TIFFfree(EncoderState(tif)->enc_hashtab); |
|
|
|
_TIFFfree(tif->tif_data); |
|
tif->tif_data = NULL; |
|
} |
|
} |
|
|
|
int |
|
TIFFInitLZW(TIFF* tif, int scheme) |
|
{ |
|
assert(scheme == COMPRESSION_LZW); |
|
/* |
|
* Allocate state block so tag methods have storage to record values. |
|
*/ |
|
tif->tif_data = (tidata_t) _TIFFmalloc(sizeof (LZWCodecState)); |
|
if (tif->tif_data == NULL) |
|
goto bad; |
|
DecoderState(tif)->dec_codetab = NULL; |
|
DecoderState(tif)->dec_decode = NULL; |
|
EncoderState(tif)->enc_hashtab = NULL; |
|
LZWState(tif)->rw_mode = tif->tif_mode; |
|
|
|
/* |
|
* Install codec methods. |
|
*/ |
|
tif->tif_setupdecode = LZWSetupDecode; |
|
tif->tif_predecode = LZWPreDecode; |
|
tif->tif_decoderow = LZWDecode; |
|
tif->tif_decodestrip = LZWDecode; |
|
tif->tif_decodetile = LZWDecode; |
|
tif->tif_setupencode = LZWSetupEncode; |
|
tif->tif_preencode = LZWPreEncode; |
|
tif->tif_postencode = LZWPostEncode; |
|
tif->tif_encoderow = LZWEncode; |
|
tif->tif_encodestrip = LZWEncode; |
|
tif->tif_encodetile = LZWEncode; |
|
tif->tif_cleanup = LZWCleanup; |
|
/* |
|
* Setup predictor setup. |
|
*/ |
|
(void) TIFFPredictorInit(tif); |
|
return (1); |
|
bad: |
|
TIFFError("TIFFInitLZW", "No space for LZW state block"); |
|
return (0); |
|
} |
|
|
|
/* |
|
* Copyright (c) 1985, 1986 The Regents of the University of California. |
|
* All rights reserved. |
|
* |
|
* This code is derived from software contributed to Berkeley by |
|
* James A. Woods, derived from original work by Spencer Thomas |
|
* and Joseph Orost. |
|
* |
|
* Redistribution and use in source and binary forms are permitted |
|
* provided that the above copyright notice and this paragraph are |
|
* duplicated in all such forms and that any documentation, |
|
* advertising materials, and other materials related to such |
|
* distribution and use acknowledge that the software was developed |
|
* by the University of California, Berkeley. The name of the |
|
* University may not be used to endorse or promote products derived |
|
* from this software without specific prior written permission. |
|
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
|
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
|
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
|
*/ |
|
#endif /* LZW_SUPPORT */ |
|
|
|
/* vim: set ts=8 sts=8 sw=8 noet: */
|
|
|