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Diffstat (limited to 'cpukit/zlib/contrib/blast/blast.c')
| -rw-r--r-- | cpukit/zlib/contrib/blast/blast.c | 444 |
1 files changed, 444 insertions, 0 deletions
diff --git a/cpukit/zlib/contrib/blast/blast.c b/cpukit/zlib/contrib/blast/blast.c new file mode 100644 index 0000000000..4ce697a41f --- /dev/null +++ b/cpukit/zlib/contrib/blast/blast.c @@ -0,0 +1,444 @@ +/* blast.c + * Copyright (C) 2003 Mark Adler + * For conditions of distribution and use, see copyright notice in blast.h + * version 1.1, 16 Feb 2003 + * + * blast.c decompresses data compressed by the PKWare Compression Library. + * This function provides functionality similar to the explode() function of + * the PKWare library, hence the name "blast". + * + * This decompressor is based on the excellent format description provided by + * Ben Rudiak-Gould in comp.compression on August 13, 2001. Interestingly, the + * example Ben provided in the post is incorrect. The distance 110001 should + * instead be 111000. When corrected, the example byte stream becomes: + * + * 00 04 82 24 25 8f 80 7f + * + * which decompresses to "AIAIAIAIAIAIA" (without the quotes). + */ + +/* + * Change history: + * + * 1.0 12 Feb 2003 - First version + * 1.1 16 Feb 2003 - Fixed distance check for > 4 GB uncompressed data + */ + +#include <setjmp.h> /* for setjmp(), longjmp(), and jmp_buf */ +#include "blast.h" /* prototype for blast() */ + +#define local static /* for local function definitions */ +#define MAXBITS 13 /* maximum code length */ +#define MAXWIN 4096 /* maximum window size */ + +/* input and output state */ +struct state { + /* input state */ + blast_in infun; /* input function provided by user */ + void *inhow; /* opaque information passed to infun() */ + unsigned char *in; /* next input location */ + unsigned left; /* available input at in */ + int bitbuf; /* bit buffer */ + int bitcnt; /* number of bits in bit buffer */ + + /* input limit error return state for bits() and decode() */ + jmp_buf env; + + /* output state */ + blast_out outfun; /* output function provided by user */ + void *outhow; /* opaque information passed to outfun() */ + unsigned next; /* index of next write location in out[] */ + int first; /* true to check distances (for first 4K) */ + unsigned char out[MAXWIN]; /* output buffer and sliding window */ +}; + +/* + * Return need bits from the input stream. This always leaves less than + * eight bits in the buffer. bits() works properly for need == 0. + * + * Format notes: + * + * - Bits are stored in bytes from the least significant bit to the most + * significant bit. Therefore bits are dropped from the bottom of the bit + * buffer, using shift right, and new bytes are appended to the top of the + * bit buffer, using shift left. + */ +local int bits(struct state *s, int need) +{ + int val; /* bit accumulator */ + + /* load at least need bits into val */ + val = s->bitbuf; + while (s->bitcnt < need) { + if (s->left == 0) { + s->left = s->infun(s->inhow, &(s->in)); + if (s->left == 0) longjmp(s->env, 1); /* out of input */ + } + val |= (int)(*(s->in)++) << s->bitcnt; /* load eight bits */ + s->left--; + s->bitcnt += 8; + } + + /* drop need bits and update buffer, always zero to seven bits left */ + s->bitbuf = val >> need; + s->bitcnt -= need; + + /* return need bits, zeroing the bits above that */ + return val & ((1 << need) - 1); +} + +/* + * Huffman code decoding tables. count[1..MAXBITS] is the number of symbols of + * each length, which for a canonical code are stepped through in order. + * symbol[] are the symbol values in canonical order, where the number of + * entries is the sum of the counts in count[]. The decoding process can be + * seen in the function decode() below. + */ +struct huffman { + short *count; /* number of symbols of each length */ + short *symbol; /* canonically ordered symbols */ +}; + +/* + * Decode a code from the stream s using huffman table h. Return the symbol or + * a negative value if there is an error. If all of the lengths are zero, i.e. + * an empty code, or if the code is incomplete and an invalid code is received, + * then -9 is returned after reading MAXBITS bits. + * + * Format notes: + * + * - The codes as stored in the compressed data are bit-reversed relative to + * a simple integer ordering of codes of the same lengths. Hence below the + * bits are pulled from the compressed data one at a time and used to + * build the code value reversed from what is in the stream in order to + * permit simple integer comparisons for decoding. + * + * - The first code for the shortest length is all ones. Subsequent codes of + * the same length are simply integer decrements of the previous code. When + * moving up a length, a one bit is appended to the code. For a complete + * code, the last code of the longest length will be all zeros. To support + * this ordering, the bits pulled during decoding are inverted to apply the + * more "natural" ordering starting with all zeros and incrementing. + */ +local int decode(struct state *s, struct huffman *h) +{ + int len; /* current number of bits in code */ + int code; /* len bits being decoded */ + int first; /* first code of length len */ + int count; /* number of codes of length len */ + int index; /* index of first code of length len in symbol table */ + int bitbuf; /* bits from stream */ + int left; /* bits left in next or left to process */ + short *next; /* next number of codes */ + + bitbuf = s->bitbuf; + left = s->bitcnt; + code = first = index = 0; + len = 1; + next = h->count + 1; + while (1) { + while (left--) { + code |= (bitbuf & 1) ^ 1; /* invert code */ + bitbuf >>= 1; + count = *next++; + if (code < first + count) { /* if length len, return symbol */ + s->bitbuf = bitbuf; + s->bitcnt = (s->bitcnt - len) & 7; + return h->symbol[index + (code - first)]; + } + index += count; /* else update for next length */ + first += count; + first <<= 1; + code <<= 1; + len++; + } + left = (MAXBITS+1) - len; + if (left == 0) break; + if (s->left == 0) { + s->left = s->infun(s->inhow, &(s->in)); + if (s->left == 0) longjmp(s->env, 1); /* out of input */ + } + bitbuf = *(s->in)++; + s->left--; + if (left > 8) left = 8; + } + return -9; /* ran out of codes */ +} + +/* + * Given a list of repeated code lengths rep[0..n-1], where each byte is a + * count (high four bits + 1) and a code length (low four bits), generate the + * list of code lengths. This compaction reduces the size of the object code. + * Then given the list of code lengths length[0..n-1] representing a canonical + * Huffman code for n symbols, construct the tables required to decode those + * codes. Those tables are the number of codes of each length, and the symbols + * sorted by length, retaining their original order within each length. The + * return value is zero for a complete code set, negative for an over- + * subscribed code set, and positive for an incomplete code set. The tables + * can be used if the return value is zero or positive, but they cannot be used + * if the return value is negative. If the return value is zero, it is not + * possible for decode() using that table to return an error--any stream of + * enough bits will resolve to a symbol. If the return value is positive, then + * it is possible for decode() using that table to return an error for received + * codes past the end of the incomplete lengths. + */ +local int construct(struct huffman *h, const unsigned char *rep, int n) +{ + int symbol; /* current symbol when stepping through length[] */ + int len; /* current length when stepping through h->count[] */ + int left; /* number of possible codes left of current length */ + short offs[MAXBITS+1]; /* offsets in symbol table for each length */ + short length[256]; /* code lengths */ + + /* convert compact repeat counts into symbol bit length list */ + symbol = 0; + do { + len = *rep++; + left = (len >> 4) + 1; + len &= 15; + do { + length[symbol++] = len; + } while (--left); + } while (--n); + n = symbol; + + /* count number of codes of each length */ + for (len = 0; len <= MAXBITS; len++) + h->count[len] = 0; + for (symbol = 0; symbol < n; symbol++) + (h->count[length[symbol]])++; /* assumes lengths are within bounds */ + if (h->count[0] == n) /* no codes! */ + return 0; /* complete, but decode() will fail */ + + /* check for an over-subscribed or incomplete set of lengths */ + left = 1; /* one possible code of zero length */ + for (len = 1; len <= MAXBITS; len++) { + left <<= 1; /* one more bit, double codes left */ + left -= h->count[len]; /* deduct count from possible codes */ + if (left < 0) return left; /* over-subscribed--return negative */ + } /* left > 0 means incomplete */ + + /* generate offsets into symbol table for each length for sorting */ + offs[1] = 0; + for (len = 1; len < MAXBITS; len++) + offs[len + 1] = offs[len] + h->count[len]; + + /* + * put symbols in table sorted by length, by symbol order within each + * length + */ + for (symbol = 0; symbol < n; symbol++) + if (length[symbol] != 0) + h->symbol[offs[length[symbol]]++] = symbol; + + /* return zero for complete set, positive for incomplete set */ + return left; +} + +/* + * Decode PKWare Compression Library stream. + * + * Format notes: + * + * - First byte is 0 if literals are uncoded or 1 if they are coded. Second + * byte is 4, 5, or 6 for the number of extra bits in the distance code. + * This is the base-2 logarithm of the dictionary size minus six. + * + * - Compressed data is a combination of literals and length/distance pairs + * terminated by an end code. Literals are either Huffman coded or + * uncoded bytes. A length/distance pair is a coded length followed by a + * coded distance to represent a string that occurs earlier in the + * uncompressed data that occurs again at the current location. + * + * - A bit preceding a literal or length/distance pair indicates which comes + * next, 0 for literals, 1 for length/distance. + * + * - If literals are uncoded, then the next eight bits are the literal, in the + * normal bit order in th stream, i.e. no bit-reversal is needed. Similarly, + * no bit reversal is needed for either the length extra bits or the distance + * extra bits. + * + * - Literal bytes are simply written to the output. A length/distance pair is + * an instruction to copy previously uncompressed bytes to the output. The + * copy is from distance bytes back in the output stream, copying for length + * bytes. + * + * - Distances pointing before the beginning of the output data are not + * permitted. + * + * - Overlapped copies, where the length is greater than the distance, are + * allowed and common. For example, a distance of one and a length of 518 + * simply copies the last byte 518 times. A distance of four and a length of + * twelve copies the last four bytes three times. A simple forward copy + * ignoring whether the length is greater than the distance or not implements + * this correctly. + */ +local int decomp(struct state *s) +{ + int lit; /* true if literals are coded */ + int dict; /* log2(dictionary size) - 6 */ + int symbol; /* decoded symbol, extra bits for distance */ + int len; /* length for copy */ + int dist; /* distance for copy */ + int copy; /* copy counter */ + unsigned char *from, *to; /* copy pointers */ + static int virgin = 1; /* build tables once */ + static short litcnt[MAXBITS+1], litsym[256]; /* litcode memory */ + static short lencnt[MAXBITS+1], lensym[16]; /* lencode memory */ + static short distcnt[MAXBITS+1], distsym[64]; /* distcode memory */ + static struct huffman litcode = {litcnt, litsym}; /* length code */ + static struct huffman lencode = {lencnt, lensym}; /* length code */ + static struct huffman distcode = {distcnt, distsym};/* distance code */ + /* bit lengths of literal codes */ + static const unsigned char litlen[] = { + 11, 124, 8, 7, 28, 7, 188, 13, 76, 4, 10, 8, 12, 10, 12, 10, 8, 23, 8, + 9, 7, 6, 7, 8, 7, 6, 55, 8, 23, 24, 12, 11, 7, 9, 11, 12, 6, 7, 22, 5, + 7, 24, 6, 11, 9, 6, 7, 22, 7, 11, 38, 7, 9, 8, 25, 11, 8, 11, 9, 12, + 8, 12, 5, 38, 5, 38, 5, 11, 7, 5, 6, 21, 6, 10, 53, 8, 7, 24, 10, 27, + 44, 253, 253, 253, 252, 252, 252, 13, 12, 45, 12, 45, 12, 61, 12, 45, + 44, 173}; + /* bit lengths of length codes 0..15 */ + static const unsigned char lenlen[] = {2, 35, 36, 53, 38, 23}; + /* bit lengths of distance codes 0..63 */ + static const unsigned char distlen[] = {2, 20, 53, 230, 247, 151, 248}; + static const short base[16] = { /* base for length codes */ + 3, 2, 4, 5, 6, 7, 8, 9, 10, 12, 16, 24, 40, 72, 136, 264}; + static const char extra[16] = { /* extra bits for length codes */ + 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8}; + + /* set up decoding tables (once--might not be thread-safe) */ + if (virgin) { + construct(&litcode, litlen, sizeof(litlen)); + construct(&lencode, lenlen, sizeof(lenlen)); + construct(&distcode, distlen, sizeof(distlen)); + virgin = 0; + } + + /* read header */ + lit = bits(s, 8); + if (lit > 1) return -1; + dict = bits(s, 8); + if (dict < 4 || dict > 6) return -2; + + /* decode literals and length/distance pairs */ + do { + if (bits(s, 1)) { + /* get length */ + symbol = decode(s, &lencode); + len = base[symbol] + bits(s, extra[symbol]); + if (len == 519) break; /* end code */ + + /* get distance */ + symbol = len == 2 ? 2 : dict; + dist = decode(s, &distcode) << symbol; + dist += bits(s, symbol); + dist++; + if (s->first && dist > s->next) + return -3; /* distance too far back */ + + /* copy length bytes from distance bytes back */ + do { + to = s->out + s->next; + from = to - dist; + copy = MAXWIN; + if (s->next < dist) { + from += copy; + copy = dist; + } + copy -= s->next; + if (copy > len) copy = len; + len -= copy; + s->next += copy; + do { + *to++ = *from++; + } while (--copy); + if (s->next == MAXWIN) { + if (s->outfun(s->outhow, s->out, s->next)) return 1; + s->next = 0; + s->first = 0; + } + } while (len != 0); + } + else { + /* get literal and write it */ + symbol = lit ? decode(s, &litcode) : bits(s, 8); + s->out[s->next++] = symbol; + if (s->next == MAXWIN) { + if (s->outfun(s->outhow, s->out, s->next)) return 1; + s->next = 0; + s->first = 0; + } + } + } while (1); + return 0; +} + +/* See comments in blast.h */ +int blast(blast_in infun, void *inhow, blast_out outfun, void *outhow) +{ + struct state s; /* input/output state */ + int err; /* return value */ + + /* initialize input state */ + s.infun = infun; + s.inhow = inhow; + s.left = 0; + s.bitbuf = 0; + s.bitcnt = 0; + + /* initialize output state */ + s.outfun = outfun; + s.outhow = outhow; + s.next = 0; + s.first = 1; + + /* return if bits() or decode() tries to read past available input */ + if (setjmp(s.env) != 0) /* if came back here via longjmp(), */ + err = 2; /* then skip decomp(), return error */ + else + err = decomp(&s); /* decompress */ + + /* write any leftover output and update the error code if needed */ + if (err != 1 && s.next && s.outfun(s.outhow, s.out, s.next) && err == 0) + err = 1; + return err; +} + +#ifdef TEST +/* Example of how to use blast() */ +#include <stdio.h> +#include <stdlib.h> + +#define CHUNK 16384 + +local unsigned inf(void *how, unsigned char **buf) +{ + static unsigned char hold[CHUNK]; + + *buf = hold; + return fread(hold, 1, CHUNK, (FILE *)how); +} + +local int outf(void *how, unsigned char *buf, unsigned len) +{ + return fwrite(buf, 1, len, (FILE *)how) != len; +} + +/* Decompress a PKWare Compression Library stream from stdin to stdout */ +int main(void) +{ + int ret, n; + + /* decompress to stdout */ + ret = blast(inf, stdin, outf, stdout); + if (ret != 0) fprintf(stderr, "blast error: %d\n", ret); + + /* see if there are any leftover bytes */ + n = 0; + while (getchar() != EOF) n++; + if (n) fprintf(stderr, "blast warning: %d unused bytes of input\n", n); + + /* return blast() error code */ + return ret; +} +#endif |