diff options
Diffstat (limited to 'filter/lzwd.c')
| -rw-r--r-- | filter/lzwd.c | 253 |
1 files changed, 0 insertions, 253 deletions
diff --git a/filter/lzwd.c b/filter/lzwd.c deleted file mode 100644 index 95fc462a..00000000 --- a/filter/lzwd.c +++ /dev/null @@ -1,253 +0,0 @@ -#include <fitz.h> - -/* TODO: error checking */ - -enum -{ - MINBITS = 9, - MAXBITS = 12, - NUMCODES = (1 << MAXBITS), - LZW_CLEAR = 256, - LZW_EOD = 257, - LZW_FIRST = 258 -}; - -typedef struct lzw_code_s lzw_code; - -struct lzw_code_s -{ - int prev; /* prev code (in string) */ - unsigned short length; /* string len, including this token */ - unsigned char value; /* data value */ - unsigned char firstchar; /* first token of string */ -}; - -typedef struct fz_lzwd_s fz_lzwd; - -struct fz_lzwd_s -{ - fz_filter super; - - int earlychange; - - unsigned int word; /* bits loaded from data */ - int bidx; - - int resume; /* resume output of code from needout */ - int codebits; /* num bits/code */ - int code; /* current code */ - int oldcode; /* previously recognized code */ - int nextcode; /* next free entry */ - lzw_code table[NUMCODES]; -}; - -fz_error * -fz_newlzwd(fz_filter **fp, fz_obj *params) -{ - int i; - - FZ_NEWFILTER(fz_lzwd, lzw, lzwd); - - lzw->earlychange = 0; - - if (params) - { - fz_obj *obj; - obj = fz_dictgets(params, "EarlyChange"); - if (obj) lzw->earlychange = fz_toint(obj) != 0; - } - - lzw->bidx = 32; - lzw->word = 0; - - for (i = 0; i < 256; i++) - { - lzw->table[i].value = i; - lzw->table[i].firstchar = i; - lzw->table[i].length = 1; - lzw->table[i].prev = -1; - } - - for (i = LZW_FIRST; i < NUMCODES; i++) - { - lzw->table[i].value = 0; - lzw->table[i].firstchar = 0; - lzw->table[i].length = 0; - lzw->table[i].prev = -1; - } - - lzw->codebits = MINBITS; - lzw->code = -1; - lzw->nextcode = LZW_FIRST; - lzw->oldcode = -1; - lzw->resume = 0; - - return nil; -} - -void -fz_droplzwd(fz_filter *filter) -{ -} - -static inline void eatbits(fz_lzwd *lzw, int nbits) -{ - lzw->word <<= nbits; - lzw->bidx += nbits; -} - -static inline fz_error * fillbits(fz_lzwd *lzw, fz_buffer *in) -{ - while (lzw->bidx >= 8) - { - if (in->rp + 1 > in->wp) - return fz_ioneedin; - lzw->bidx -= 8; - lzw->word |= *in->rp << lzw->bidx; - in->rp ++; - } - return nil; -} - -static inline void unstuff(fz_lzwd *lzw, fz_buffer *in) -{ - int i = (32 - lzw->bidx) / 8; - while (i-- && in->rp > in->bp) - in->rp --; -} - -fz_error * -fz_processlzwd(fz_filter *filter, fz_buffer *in, fz_buffer *out) -{ - fz_lzwd *lzw = (fz_lzwd*)filter; - unsigned char *s; - int len; - - if (lzw->resume) - { - lzw->resume = 0; - goto output; - } - - while (1) - { - if (fillbits(lzw, in)) - { - if (in->eof) - { - if (lzw->bidx > 32 - lzw->codebits) - { - out->eof = 1; - unstuff(lzw, in); - return fz_iodone; - } - } - else - { - return fz_ioneedin; - } - } - - lzw->code = lzw->word >> (32 - lzw->codebits); - - if (lzw->code == LZW_EOD) - { - eatbits(lzw, lzw->codebits); - out->eof = 1; - unstuff(lzw, in); - return fz_iodone; - } - - if (lzw->code == LZW_CLEAR) - { - int oldcodebits = lzw->codebits; - - lzw->codebits = MINBITS; - lzw->nextcode = LZW_FIRST; - - lzw->code = lzw->word >> (32 - oldcodebits - MINBITS) & ((1 << MINBITS) - 1); - - if (lzw->code == LZW_EOD) - { - eatbits(lzw, oldcodebits + MINBITS); - out->eof = 1; - unstuff(lzw, in); - return fz_iodone; - } - - if (out->wp + 1 > out->ep) - return fz_ioneedout; - - *out->wp++ = lzw->code; - - lzw->oldcode = lzw->code; - - eatbits(lzw, oldcodebits + MINBITS); - - continue; - } - - eatbits(lzw, lzw->codebits); - - /* if stream starts without a clear code, oldcode is undefined... */ - if (lzw->oldcode == -1) - { - lzw->oldcode = lzw->code; - goto output; - } - - /* add new entry to the code table */ - lzw->table[lzw->nextcode].prev = lzw->oldcode; - lzw->table[lzw->nextcode].firstchar = lzw->table[lzw->oldcode].firstchar; - lzw->table[lzw->nextcode].length = lzw->table[lzw->oldcode].length + 1; - if (lzw->code < lzw->nextcode) - lzw->table[lzw->nextcode].value = lzw->table[lzw->code].firstchar; - else - lzw->table[lzw->nextcode].value = lzw->table[lzw->nextcode].firstchar; - - lzw->nextcode ++; - - if (lzw->nextcode >= (1 << lzw->codebits) - lzw->earlychange - 1) - { - lzw->codebits ++; - if (lzw->codebits > MAXBITS) - lzw->codebits = MAXBITS; /* FIXME */ - } - - lzw->oldcode = lzw->code; - -output: - /* code maps to a string, copy to output (in reverse...) */ - if (lzw->code > 255) - { - if (out->wp + lzw->table[lzw->code].length > out->ep) - { - lzw->resume = 1; - return fz_ioneedout; - } - - len = lzw->table[lzw->code].length; - s = out->wp + len; - - do - { - *(--s) = lzw->table[lzw->code].value; - lzw->code = lzw->table[lzw->code].prev; - } while (lzw->code >= 0 && s > out->wp); - out->wp += len; - } - - /* ... or just a single character */ - else - { - if (out->wp + 1 > out->ep) - { - lzw->resume = 1; - return fz_ioneedout; - } - - *out->wp++ = lzw->code; - } - } -} - |