/* Id */ /* * 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 /* * 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) { \ TIFFWarningExt(_tif->tif_clientdata, _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) { TIFFErrorExt(tif->tif_clientdata, "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) { TIFFErrorExt(tif->tif_clientdata, 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) { TIFFWarningExt(tif->tif_clientdata, 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) { TIFFErrorExt(tif->tif_clientdata, 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) { TIFFErrorExt(tif->tif_clientdata, 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]) { TIFFErrorExt(tif->tif_clientdata, 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]) { TIFFErrorExt(tif->tif_clientdata, 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) { TIFFErrorExt(tif->tif_clientdata, 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) { TIFFErrorExt(tif->tif_clientdata, 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]) { TIFFErrorExt(tif->tif_clientdata, 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]) { TIFFErrorExt(tif->tif_clientdata, 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) { TIFFErrorExt(tif->tif_clientdata, 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) { TIFFErrorExt(tif->tif_clientdata, 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) { TIFFErrorExt(tif->tif_clientdata, 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) { (void)TIFFPredictorCleanup(tif); assert(tif->tif_data != 0); 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; _TIFFSetDefaultCompressionState(tif); } int TIFFInitLZW(TIFF* tif, int scheme) { assert(scheme == COMPRESSION_LZW); (void)scheme; /* * 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: TIFFErrorExt(tif->tif_clientdata, "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: */