--- /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