+++ /dev/null
-/* $Id: tif_lzw.c,v 1.1 2005/06/17 13:54:52 vp153 Exp $ */
-
-/*
- * Copyright (c) 1988-1997 Sam Leffler
- * Copyright (c) 1991-1997 Silicon Graphics, Inc.
- *
- * Permission to use, copy, modify, distribute, and sell this software and
- * its documentation for any purpose is hereby granted without fee, provided
- * that (i) the above copyright notices and this permission notice appear in
- * all copies of the software and related documentation, and (ii) the names of
- * Sam Leffler and Silicon Graphics may not be used in any advertising or
- * publicity relating to the software without the specific, prior written
- * permission of Sam Leffler and Silicon Graphics.
- *
- * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
- * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
- *
- * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
- * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
- * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
- * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
- * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
- * OF THIS SOFTWARE.
- */
-
-#include "tiffiop.h"
-#ifdef LZW_SUPPORT
-/*
- * TIFF Library.
- * Rev 5.0 Lempel-Ziv & Welch Compression Support
- *
- * This code is derived from the compress program whose code is
- * derived from software contributed to Berkeley by James A. Woods,
- * derived from original work by Spencer Thomas and Joseph Orost.
- *
- * The original Berkeley copyright notice appears below in its entirety.
- */
-#include "tif_predict.h"
-
-#include <stdio.h>
-
-/*
- * NB: The 5.0 spec describes a different algorithm than Aldus
- * implements. Specifically, Aldus does code length transitions
- * one code earlier than should be done (for real LZW).
- * Earlier versions of this library implemented the correct
- * LZW algorithm, but emitted codes in a bit order opposite
- * to the TIFF spec. Thus, to maintain compatibility w/ Aldus
- * we interpret MSB-LSB ordered codes to be images written w/
- * old versions of this library, but otherwise adhere to the
- * Aldus "off by one" algorithm.
- *
- * Future revisions to the TIFF spec are expected to "clarify this issue".
- */
-#define LZW_COMPAT /* include backwards compatibility code */
-/*
- * Each strip of data is supposed to be terminated by a CODE_EOI.
- * If the following #define is included, the decoder will also
- * check for end-of-strip w/o seeing this code. This makes the
- * library more robust, but also slower.
- */
-#define LZW_CHECKEOS /* include checks for strips w/o EOI code */
-
-#define MAXCODE(n) ((1L<<(n))-1)
-/*
- * The TIFF spec specifies that encoded bit
- * strings range from 9 to 12 bits.
- */
-#define BITS_MIN 9 /* start with 9 bits */
-#define BITS_MAX 12 /* max of 12 bit strings */
-/* predefined codes */
-#define CODE_CLEAR 256 /* code to clear string table */
-#define CODE_EOI 257 /* end-of-information code */
-#define CODE_FIRST 258 /* first free code entry */
-#define CODE_MAX MAXCODE(BITS_MAX)
-#define HSIZE 9001L /* 91% occupancy */
-#define HSHIFT (13-8)
-#ifdef LZW_COMPAT
-/* NB: +1024 is for compatibility with old files */
-#define CSIZE (MAXCODE(BITS_MAX)+1024L)
-#else
-#define CSIZE (MAXCODE(BITS_MAX)+1L)
-#endif
-
-/*
- * State block for each open TIFF file using LZW
- * compression/decompression. Note that the predictor
- * state block must be first in this data structure.
- */
-typedef struct {
- TIFFPredictorState predict; /* predictor super class */
-
- unsigned short nbits; /* # of bits/code */
- unsigned short maxcode; /* maximum code for lzw_nbits */
- unsigned short free_ent; /* next free entry in hash table */
- long nextdata; /* next bits of i/o */
- long nextbits; /* # of valid bits in lzw_nextdata */
-
- int rw_mode; /* preserve rw_mode from init */
-} LZWBaseState;
-
-#define lzw_nbits base.nbits
-#define lzw_maxcode base.maxcode
-#define lzw_free_ent base.free_ent
-#define lzw_nextdata base.nextdata
-#define lzw_nextbits base.nextbits
-
-/*
- * Encoding-specific state.
- */
-typedef uint16 hcode_t; /* codes fit in 16 bits */
-typedef struct {
- long hash;
- hcode_t code;
-} hash_t;
-
-/*
- * Decoding-specific state.
- */
-typedef struct code_ent {
- struct code_ent *next;
- unsigned short length; /* string len, including this token */
- unsigned char value; /* data value */
- unsigned char firstchar; /* first token of string */
-} code_t;
-
-typedef int (*decodeFunc)(TIFF*, tidata_t, tsize_t, tsample_t);
-
-typedef struct {
- LZWBaseState base;
-
- /* Decoding specific data */
- long dec_nbitsmask; /* lzw_nbits 1 bits, right adjusted */
- long dec_restart; /* restart count */
-#ifdef LZW_CHECKEOS
- long dec_bitsleft; /* available bits in raw data */
-#endif
- decodeFunc dec_decode; /* regular or backwards compatible */
- code_t* dec_codep; /* current recognized code */
- code_t* dec_oldcodep; /* previously recognized code */
- code_t* dec_free_entp; /* next free entry */
- code_t* dec_maxcodep; /* max available entry */
- code_t* dec_codetab; /* kept separate for small machines */
-
- /* Encoding specific data */
- int enc_oldcode; /* last code encountered */
- long enc_checkpoint; /* point at which to clear table */
-#define CHECK_GAP 10000 /* enc_ratio check interval */
- long enc_ratio; /* current compression ratio */
- long enc_incount; /* (input) data bytes encoded */
- long enc_outcount; /* encoded (output) bytes */
- tidata_t enc_rawlimit; /* bound on tif_rawdata buffer */
- hash_t* enc_hashtab; /* kept separate for small machines */
-} LZWCodecState;
-
-#define LZWState(tif) ((LZWBaseState*) (tif)->tif_data)
-#define DecoderState(tif) ((LZWCodecState*) LZWState(tif))
-#define EncoderState(tif) ((LZWCodecState*) LZWState(tif))
-
-static int LZWDecode(TIFF*, tidata_t, tsize_t, tsample_t);
-#ifdef LZW_COMPAT
-static int LZWDecodeCompat(TIFF*, tidata_t, tsize_t, tsample_t);
-#endif
-static void cl_hash(LZWCodecState*);
-
-/*
- * LZW Decoder.
- */
-
-#ifdef LZW_CHECKEOS
-/*
- * This check shouldn't be necessary because each
- * strip is suppose to be terminated with CODE_EOI.
- */
-#define NextCode(_tif, _sp, _bp, _code, _get) { \
- if ((_sp)->dec_bitsleft < nbits) { \
- TIFFWarning(_tif->tif_name, \
- "LZWDecode: Strip %d not terminated with EOI code", \
- _tif->tif_curstrip); \
- _code = CODE_EOI; \
- } else { \
- _get(_sp,_bp,_code); \
- (_sp)->dec_bitsleft -= nbits; \
- } \
-}
-#else
-#define NextCode(tif, sp, bp, code, get) get(sp, bp, code)
-#endif
-
-static int
-LZWSetupDecode(TIFF* tif)
-{
- LZWCodecState* sp = DecoderState(tif);
- static const char module[] = " LZWSetupDecode";
- int code;
-
- if( sp == NULL )
- {
- /*
- * Allocate state block so tag methods have storage to record
- * values.
- */
- tif->tif_data = (tidata_t) _TIFFmalloc(sizeof(LZWCodecState));
- if (tif->tif_data == NULL)
- {
- TIFFError("LZWPreDecode", "No space for LZW state block");
- return (0);
- }
-
- DecoderState(tif)->dec_codetab = NULL;
- DecoderState(tif)->dec_decode = NULL;
-
- /*
- * Setup predictor setup.
- */
- (void) TIFFPredictorInit(tif);
-
- sp = DecoderState(tif);
- }
-
- assert(sp != NULL);
-
- if (sp->dec_codetab == NULL) {
- sp->dec_codetab = (code_t*)_TIFFmalloc(CSIZE*sizeof (code_t));
- if (sp->dec_codetab == NULL) {
- TIFFError(module, "No space for LZW code table");
- return (0);
- }
- /*
- * Pre-load the table.
- */
- code = 255;
- do {
- sp->dec_codetab[code].value = code;
- sp->dec_codetab[code].firstchar = code;
- sp->dec_codetab[code].length = 1;
- sp->dec_codetab[code].next = NULL;
- } while (code--);
- }
- return (1);
-}
-
-/*
- * Setup state for decoding a strip.
- */
-static int
-LZWPreDecode(TIFF* tif, tsample_t s)
-{
- LZWCodecState *sp = DecoderState(tif);
-
- (void) s;
- assert(sp != NULL);
- /*
- * Check for old bit-reversed codes.
- */
- if (tif->tif_rawdata[0] == 0 && (tif->tif_rawdata[1] & 0x1)) {
-#ifdef LZW_COMPAT
- if (!sp->dec_decode) {
- TIFFWarning(tif->tif_name,
- "Old-style LZW codes, convert file");
- /*
- * Override default decoding methods with
- * ones that deal with the old coding.
- * Otherwise the predictor versions set
- * above will call the compatibility routines
- * through the dec_decode method.
- */
- tif->tif_decoderow = LZWDecodeCompat;
- tif->tif_decodestrip = LZWDecodeCompat;
- tif->tif_decodetile = LZWDecodeCompat;
- /*
- * If doing horizontal differencing, must
- * re-setup the predictor logic since we
- * switched the basic decoder methods...
- */
- (*tif->tif_setupdecode)(tif);
- sp->dec_decode = LZWDecodeCompat;
- }
- sp->lzw_maxcode = MAXCODE(BITS_MIN);
-#else /* !LZW_COMPAT */
- if (!sp->dec_decode) {
- TIFFError(tif->tif_name,
- "Old-style LZW codes not supported");
- sp->dec_decode = LZWDecode;
- }
- return (0);
-#endif/* !LZW_COMPAT */
- } else {
- sp->lzw_maxcode = MAXCODE(BITS_MIN)-1;
- sp->dec_decode = LZWDecode;
- }
- sp->lzw_nbits = BITS_MIN;
- sp->lzw_nextbits = 0;
- sp->lzw_nextdata = 0;
-
- sp->dec_restart = 0;
- sp->dec_nbitsmask = MAXCODE(BITS_MIN);
-#ifdef LZW_CHECKEOS
- sp->dec_bitsleft = tif->tif_rawcc << 3;
-#endif
- sp->dec_free_entp = sp->dec_codetab + CODE_FIRST;
- /*
- * Zero entries that are not yet filled in. We do
- * this to guard against bogus input data that causes
- * us to index into undefined entries. If you can
- * come up with a way to safely bounds-check input codes
- * while decoding then you can remove this operation.
- */
- _TIFFmemset(sp->dec_free_entp, 0, (CSIZE-CODE_FIRST)*sizeof (code_t));
- sp->dec_oldcodep = &sp->dec_codetab[-1];
- sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask-1];
- return (1);
-}
-
-/*
- * Decode a "hunk of data".
- */
-#define GetNextCode(sp, bp, code) { \
- nextdata = (nextdata<<8) | *(bp)++; \
- nextbits += 8; \
- if (nextbits < nbits) { \
- nextdata = (nextdata<<8) | *(bp)++; \
- nextbits += 8; \
- } \
- code = (hcode_t)((nextdata >> (nextbits-nbits)) & nbitsmask); \
- nextbits -= nbits; \
-}
-
-static void
-codeLoop(TIFF* tif)
-{
- TIFFError(tif->tif_name,
- "LZWDecode: Bogus encoding, loop in the code table; scanline %d",
- tif->tif_row);
-}
-
-static int
-LZWDecode(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
-{
- LZWCodecState *sp = DecoderState(tif);
- char *op = (char*) op0;
- long occ = (long) occ0;
- char *tp;
- unsigned char *bp;
- hcode_t code;
- int len;
- long nbits, nextbits, nextdata, nbitsmask;
- code_t *codep, *free_entp, *maxcodep, *oldcodep;
-
- (void) s;
- assert(sp != NULL);
- /*
- * Restart interrupted output operation.
- */
- if (sp->dec_restart) {
- long residue;
-
- 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 && codep);
- if (codep) {
- tp = op + occ;
- do {
- *--tp = codep->value;
- codep = codep->next;
- } while (--occ && codep);
- }
- return (1);
- }
- /*
- * Residue satisfies only part of the decode request.
- */
- op += residue, occ -= residue;
- tp = op;
- do {
- int t;
- --tp;
- t = codep->value;
- codep = codep->next;
- *tp = t;
- } while (--residue && codep);
- 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, GetNextCode);
- 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-1;
- NextCode(tif, sp, bp, code, GetNextCode);
- if (code == CODE_EOI)
- break;
- *op++ = (char)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,
- "LZWDecode: 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,
- "LZWDecode: 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-1;
- }
- 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,
- "LZWDecode: 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 && codep->length > occ);
- if (codep) {
- sp->dec_restart = occ;
- tp = op + occ;
- do {
- *--tp = codep->value;
- codep = codep->next;
- } while (--occ && codep);
- if (codep)
- codeLoop(tif);
- }
- break;
- }
- len = codep->length;
- tp = op + len;
- do {
- int t;
- --tp;
- t = codep->value;
- codep = codep->next;
- *tp = t;
- } while (codep && tp > op);
- if (codep) {
- codeLoop(tif);
- break;
- }
- op += len, occ -= len;
- } else
- *op++ = (char)code, occ--;
- }
-
- tif->tif_rawcp = (tidata_t) bp;
- sp->lzw_nbits = (unsigned short) 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,
- "LZWDecode: Not enough data at scanline %d (short %d bytes)",
- tif->tif_row, occ);
- return (0);
- }
- return (1);
-}
-
-#ifdef LZW_COMPAT
-/*
- * Decode a "hunk of data" for old images.
- */
-#define GetNextCodeCompat(sp, bp, code) { \
- nextdata |= (unsigned long) *(bp)++ << nextbits; \
- nextbits += 8; \
- if (nextbits < nbits) { \
- nextdata |= (unsigned long) *(bp)++ << nextbits;\
- nextbits += 8; \
- } \
- code = (hcode_t)(nextdata & nbitsmask); \
- nextdata >>= nbits; \
- nextbits -= nbits; \
-}
-
-static int
-LZWDecodeCompat(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
-{
- LZWCodecState *sp = DecoderState(tif);
- char *op = (char*) op0;
- long occ = (long) occ0;
- char *tp;
- unsigned char *bp;
- int code, nbits;
- long nextbits, nextdata, nbitsmask;
- code_t *codep, *free_entp, *maxcodep, *oldcodep;
-
- (void) s;
- assert(sp != NULL);
- /*
- * Restart interrupted output operation.
- */
- if (sp->dec_restart) {
- long residue;
-
- 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: */
projects / opencv / blobdiff