contrib/blast/blast.c

3  * For conditions of distribution and use, see copyright notice in blast.h
11  * Ben Rudiak-Gould in comp.compression on August 13, 2001.  Interestingly, the
12  * example Ben provided in the post is incorrect.  The distance 110001 should
25  * 1.2  24 Oct 2012     - Add note about using binary mode in stdio
41     unsigned char *in;          /* next input location */
42     unsigned left;              /* available input at in */
44     int bitcnt;                 /* number of bits in bit buffer */
52     unsigned next;              /* index of next write location in out[] */
59  * eight bits in the buffer.  bits() works properly for need == 0.
63  * - Bits are stored in bytes from the least significant bit to the most
76             s->left = s->infun(s->inhow, &(s->in));
79         val |= (int)(*(s->in)++) << s->bitcnt;          /* load eight bits */
94  * each length, which for a canonical code are stepped through in order.
95  * symbol[] are the symbol values in canonical order, where the number of
96  * entries is the sum of the counts in count[].  The decoding process can be
97  * seen in the function decode() below.
112  * - The codes as stored in the compressed data are bit-reversed relative to
115  *   build the code value reversed from what is in the stream in order to
127     int len;            /* current number of bits in code */
131     int index;          /* index of first code of length len in symbol table */
133     int left;           /* bits left in next or left to process */
160             s->left = s->infun(s->inhow, &(s->in));
163         bitbuf = *(s->in)++;
192     short offs[MAXBITS+1];      /* offsets in symbol table for each length */
229      * put symbols in table sorted by length, by symbol order within each
246  *   byte is 4, 5, or 6 for the number of extra bits in the distance code.
252  *   coded distance to represent a string that occurs earlier in the
258  * - If literals are uncoded, then the next eight bits are the literal, in the
259  *   normal bit order in th stream, i.e. no bit-reversal is needed. Similarly,
265  *   copy is from distance bytes back in the output stream, copying for length
378 /* See comments in blast.h */