diff options
Diffstat (limited to 'fitz/filt_lzwe.c')
| -rw-r--r-- | fitz/filt_lzwe.c | 261 |
1 files changed, 0 insertions, 261 deletions
diff --git a/fitz/filt_lzwe.c b/fitz/filt_lzwe.c deleted file mode 100644 index 6b271dfa..00000000 --- a/fitz/filt_lzwe.c +++ /dev/null @@ -1,261 +0,0 @@ -#include "fitz_base.h" -#include "fitz_stream.h" - -#define noDEBUG 1 - -enum -{ - MINBITS = 9, - MAXBITS = 12, - MAXBYTES = 2, - NUMCODES = (1 << MAXBITS), - LZW_CLEAR = 256, - LZW_EOD = 257, - LZW_FIRST = 258, - HSIZE = 9001, /* 91% occupancy (???) */ - HSHIFT = (13 - 8) -}; - -typedef struct lzw_hash_s lzw_hash; - -struct lzw_hash_s -{ - int hash; - int code; -}; - -typedef struct fz_lzwe_s fz_lzwe; - -struct fz_lzwe_s -{ - fz_filter super; - - int earlychange; - - int bidx; /* partial bits used in out->wp */ - unsigned char bsave; /* partial byte saved between process() calls */ - - int resume; - int code; - int fcode; - int hcode; - - int codebits; - int oldcode; - int nextcode; - - lzw_hash table[HSIZE]; -}; - -static void -clearhash(fz_lzwe *lzw) -{ - int i; - for (i = 0; i < HSIZE; i++) - lzw->table[i].hash = -1; -} - -fz_error -fz_newlzwe(fz_filter **fp, fz_obj *params) -{ - FZ_NEWFILTER(fz_lzwe, lzw, lzwe); - - lzw->earlychange = 0; - - if (params) - { - fz_obj *obj; - obj = fz_dictgets(params, "EarlyChange"); - if (obj) lzw->earlychange = fz_toint(obj) != 0; - } - - lzw->bidx = 0; - lzw->bsave = 0; - - lzw->resume = 0; - lzw->code = -1; - lzw->hcode = -1; - lzw->fcode = -1; - - lzw->codebits = MINBITS; - lzw->nextcode = LZW_FIRST; - lzw->oldcode = -1; /* generates LZW_CLEAR */ - - clearhash(lzw); - - return fz_okay; -} - -void -fz_droplzwe(fz_filter *filter) -{ -} - -static void -putcode(fz_lzwe *lzw, fz_buffer *out, int code) -{ - int nbits = lzw->codebits; - - while (nbits > 0) - { - if (lzw->bidx == 0) - { - *out->wp = 0; - } - - /* code does not fit: shift right */ - if (nbits > (8 - lzw->bidx)) - { - *out->wp |= code >> (nbits - (8 - lzw->bidx)); - nbits = nbits - (8 - lzw->bidx); - lzw->bidx = 0; - out->wp ++; - } - - /* shift left */ - else - { - *out->wp |= code << ((8 - lzw->bidx) - nbits); - lzw->bidx += nbits; - if (lzw->bidx == 8) - { - lzw->bidx = 0; - out->wp ++; - } - nbits = 0; - } - } -} - - -static fz_error -compress(fz_lzwe *lzw, fz_buffer *in, fz_buffer *out) -{ - if (lzw->resume) - { - lzw->resume = 0; - goto resume; - } - - /* at start of data, output a clear code */ - if (lzw->oldcode == -1) - { - if (out->wp + 3 > out->ep) - return fz_ioneedout; - - if (in->rp + 1 > in->wp) - { - if (in->eof) - goto eof; - return fz_ioneedin; - } - - putcode(lzw, out, LZW_CLEAR); - - lzw->oldcode = *in->rp++; - } - -begin: - while (1) - { - if (in->rp + 1 > in->wp) - { - if (in->eof) - goto eof; - return fz_ioneedin; - } - - /* read character */ - lzw->code = *in->rp++; - - /* hash string + character */ - lzw->fcode = (lzw->code << MAXBITS) + lzw->oldcode; - lzw->hcode = (lzw->code << HSHIFT) ^ lzw->oldcode; - - /* primary hash */ - if (lzw->table[lzw->hcode].hash == lzw->fcode) - { - lzw->oldcode = lzw->table[lzw->hcode].code; - continue; - } - - /* secondary hash */ - if (lzw->table[lzw->hcode].hash != -1) - { - int disp = HSIZE - lzw->hcode; - if (lzw->hcode == 0) - disp = 1; - do - { - lzw->hcode = lzw->hcode - disp; - if (lzw->hcode < 0) - lzw->hcode += HSIZE; - if (lzw->table[lzw->hcode].hash == lzw->fcode) - { - lzw->oldcode = lzw->table[lzw->hcode].code; - goto begin; - } - } while (lzw->table[lzw->hcode].hash != -1); - } - -resume: - /* new entry: emit code and add to table */ - - /* reserve space for this code and an eventual CLEAR code */ - if (out->wp + 5 > out->ep) - { - lzw->resume = 1; - return fz_ioneedout; - } - - putcode(lzw, out, lzw->oldcode); - - lzw->oldcode = lzw->code; - lzw->table[lzw->hcode].code = lzw->nextcode; - lzw->table[lzw->hcode].hash = lzw->fcode; - - lzw->nextcode ++; - - /* table is full: emit clear code and reset */ - if (lzw->nextcode == NUMCODES - 1) - { - putcode(lzw, out, LZW_CLEAR); - clearhash(lzw); - lzw->nextcode = LZW_FIRST; - lzw->codebits = MINBITS; - } - - /* check if next entry will be too big for the code size */ - else if (lzw->nextcode >= (1 << lzw->codebits) - lzw->earlychange) - { - lzw->codebits ++; - } - } - -eof: - if (out->wp + 5 > out->ep) - return fz_ioneedout; - - putcode(lzw, out, lzw->oldcode); - putcode(lzw, out, LZW_EOD); - - return fz_iodone; -} - -fz_error -fz_processlzwe(fz_filter *filter, fz_buffer *in, fz_buffer *out) -{ - fz_lzwe *lzw = (fz_lzwe*)filter; - fz_error error; - - /* restore partial bits */ - *out->wp = lzw->bsave; - - error = compress(lzw, in, out); - - /* save partial bits */ - lzw->bsave = *out->wp; - - return error; -} - |