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Diffstat (limited to 'app/tools/halibut/deflate.c')
| -rw-r--r-- | app/tools/halibut/deflate.c | 2781 |
1 files changed, 2781 insertions, 0 deletions
diff --git a/app/tools/halibut/deflate.c b/app/tools/halibut/deflate.c new file mode 100644 index 0000000..685097b --- /dev/null +++ b/app/tools/halibut/deflate.c @@ -0,0 +1,2781 @@ +/* + * Reimplementation of Deflate (RFC1951) compression. Adapted from + * the version in PuTTY, and extended to write dynamic Huffman + * trees and choose block boundaries usefully. + */ + +/* + * TODO: + * + * - Feature: could do with forms of flush other than SYNC_FLUSH. + * I'm not sure exactly how those work when you don't know in + * advance that your next block will be static (as we did in + * PuTTY). And remember the 9-bit limitation of zlib. + * + also, zlib has FULL_FLUSH which clears the LZ77 state as + * well, for random access. + * + * - Compression quality: chooseblock() appears to be computing + * wildly inaccurate block size estimates. Possible resolutions: + * + find and fix some trivial bug I haven't spotted yet + * + abandon the entropic approximation and go with trial + * Huffman runs + * + * - Compression quality: see if increasing SYMLIMIT causes + * dynamic blocks to start being consistently smaller than it. + * + actually we seem to be there already, but check on a + * larger corpus. + * + * - Compression quality: we ought to be able to fall right back + * to actual uncompressed blocks if really necessary, though + * it's not clear what the criterion for doing so would be. + */ + +/* + * This software is copyright 2000-2006 Simon Tatham. + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, + * copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following + * conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES + * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE + * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR + * IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include <stdio.h> +#include <stddef.h> +#include <string.h> +#include <stdlib.h> +#include <assert.h> + +#include "deflate.h" + +#define snew(type) ( (type *) malloc(sizeof(type)) ) +#define snewn(n, type) ( (type *) malloc((n) * sizeof(type)) ) +#define sresize(x, n, type) ( (type *) realloc((x), (n) * sizeof(type)) ) +#define sfree(x) ( free((x)) ) + +#define lenof(x) (sizeof((x)) / sizeof(*(x))) + +#ifndef FALSE +#define FALSE 0 +#define TRUE (!FALSE) +#endif + +/* ---------------------------------------------------------------------- + * This file can be compiled in a number of modes. + * + * With -DSTANDALONE, it builds a self-contained deflate tool which + * can compress, decompress, and also analyse a deflated file to + * print out the sequence of literals and copy commands it + * contains. + * + * With -DTESTMODE, it builds a test application which is given a + * file on standard input, both compresses and decompresses it, and + * outputs the re-decompressed result so it can be conveniently + * diffed against the original. Define -DTESTDBG as well for lots + * of diagnostics. + */ + +#if defined TESTDBG +/* gcc-specific diagnostic macro */ +#define debug_int(x...) ( fprintf(stderr, x) ) +#define debug(x) ( debug_int x ) +#else +#define debug(x) +#endif + +#ifdef STANDALONE +#define ANALYSIS +#endif + +#ifdef ANALYSIS +int analyse_level = 0; +#endif + +/* ---------------------------------------------------------------------- + * Basic LZ77 code. This bit is designed modularly, so it could be + * ripped out and used in a different LZ77 compressor. Go to it, + * and good luck :-) + */ + +struct LZ77InternalContext; +struct LZ77Context { + struct LZ77InternalContext *ictx; + void *userdata; + void (*literal) (struct LZ77Context * ctx, unsigned char c); + void (*match) (struct LZ77Context * ctx, int distance, int len); +}; + +/* + * Initialise the private fields of an LZ77Context. It's up to the + * user to initialise the public fields. + */ +static int lz77_init(struct LZ77Context *ctx); + +/* + * Supply data to be compressed. Will update the private fields of + * the LZ77Context, and will call literal() and match() to output. + * If `compress' is FALSE, it will never emit a match, but will + * instead call literal() for everything. + */ +static void lz77_compress(struct LZ77Context *ctx, + const unsigned char *data, int len, int compress); + +/* + * Modifiable parameters. + */ +#define WINSIZE 32768 /* window size. Must be power of 2! */ +#define HASHMAX 2039 /* one more than max hash value */ +#define MAXMATCH 32 /* how many matches we track */ +#define HASHCHARS 3 /* how many chars make a hash */ + +/* + * This compressor takes a less slapdash approach than the + * gzip/zlib one. Rather than allowing our hash chains to fall into + * disuse near the far end, we keep them doubly linked so we can + * _find_ the far end, and then every time we add a new byte to the + * window (thus rolling round by one and removing the previous + * byte), we can carefully remove the hash chain entry. + */ + +#define INVALID -1 /* invalid hash _and_ invalid offset */ +struct WindowEntry { + short next, prev; /* array indices within the window */ + short hashval; +}; + +struct HashEntry { + short first; /* window index of first in chain */ +}; + +struct Match { + int distance, len; +}; + +struct LZ77InternalContext { + struct WindowEntry win[WINSIZE]; + unsigned char data[WINSIZE]; + int winpos; + struct HashEntry hashtab[HASHMAX]; + unsigned char pending[HASHCHARS]; + int npending; +}; + +static int lz77_hash(const unsigned char *data) +{ + return (257 * data[0] + 263 * data[1] + 269 * data[2]) % HASHMAX; +} + +static int lz77_init(struct LZ77Context *ctx) +{ + struct LZ77InternalContext *st; + int i; + + st = snew(struct LZ77InternalContext); + if (!st) + return 0; + + ctx->ictx = st; + + for (i = 0; i < WINSIZE; i++) + st->win[i].next = st->win[i].prev = st->win[i].hashval = INVALID; + for (i = 0; i < HASHMAX; i++) + st->hashtab[i].first = INVALID; + st->winpos = 0; + + st->npending = 0; + + return 1; +} + +static void lz77_advance(struct LZ77InternalContext *st, + unsigned char c, int hash) +{ + int off; + + /* + * Remove the hash entry at winpos from the tail of its chain, + * or empty the chain if it's the only thing on the chain. + */ + if (st->win[st->winpos].prev != INVALID) { + st->win[st->win[st->winpos].prev].next = INVALID; + } else if (st->win[st->winpos].hashval != INVALID) { + st->hashtab[st->win[st->winpos].hashval].first = INVALID; + } + + /* + * Create a new entry at winpos and add it to the head of its + * hash chain. + */ + st->win[st->winpos].hashval = hash; + st->win[st->winpos].prev = INVALID; + off = st->win[st->winpos].next = st->hashtab[hash].first; + st->hashtab[hash].first = st->winpos; + if (off != INVALID) + st->win[off].prev = st->winpos; + st->data[st->winpos] = c; + + /* + * Advance the window pointer. + */ + st->winpos = (st->winpos + 1) & (WINSIZE - 1); +} + +#define CHARAT(k) ( (k)<0 ? st->data[(st->winpos+k)&(WINSIZE-1)] : data[k] ) + +static void lz77_compress(struct LZ77Context *ctx, + const unsigned char *data, int len, int compress) +{ + struct LZ77InternalContext *st = ctx->ictx; + int i, hash, distance, off, nmatch, matchlen, advance; + struct Match defermatch, matches[MAXMATCH]; + int deferchr; + + /* + * Add any pending characters from last time to the window. (We + * might not be able to.) + */ + for (i = 0; i < st->npending; i++) { + unsigned char foo[HASHCHARS]; + int j; + if (len + st->npending - i < HASHCHARS) { + /* Update the pending array. */ + for (j = i; j < st->npending; j++) + st->pending[j - i] = st->pending[j]; + break; + } + for (j = 0; j < HASHCHARS; j++) + foo[j] = (i + j < st->npending ? st->pending[i + j] : + data[i + j - st->npending]); + lz77_advance(st, foo[0], lz77_hash(foo)); + } + st->npending -= i; + + defermatch.len = 0; + deferchr = '\0'; + while (len > 0) { + + /* Don't even look for a match, if we're not compressing. */ + if (compress && len >= HASHCHARS) { + /* + * Hash the next few characters. + */ + hash = lz77_hash(data); + + /* + * Look the hash up in the corresponding hash chain and see + * what we can find. + */ + nmatch = 0; + for (off = st->hashtab[hash].first; + off != INVALID; off = st->win[off].next) { + /* distance = 1 if off == st->winpos-1 */ + /* distance = WINSIZE if off == st->winpos */ + distance = + WINSIZE - (off + WINSIZE - st->winpos) % WINSIZE; + for (i = 0; i < HASHCHARS; i++) + if (CHARAT(i) != CHARAT(i - distance)) + break; + if (i == HASHCHARS) { + matches[nmatch].distance = distance; + matches[nmatch].len = 3; + if (++nmatch >= MAXMATCH) + break; + } + } + } else { + nmatch = 0; + hash = INVALID; + } + + if (nmatch > 0) { + /* + * We've now filled up matches[] with nmatch potential + * matches. Follow them down to find the longest. (We + * assume here that it's always worth favouring a + * longer match over a shorter one.) + */ + matchlen = HASHCHARS; + while (matchlen < len) { + int j; + for (i = j = 0; i < nmatch; i++) { + if (CHARAT(matchlen) == + CHARAT(matchlen - matches[i].distance)) { + matches[j++] = matches[i]; + } + } + if (j == 0) + break; + matchlen++; + nmatch = j; + } + + /* + * We've now got all the longest matches. We favour the + * shorter distances, which means we go with matches[0]. + * So see if we want to defer it or throw it away. + */ + matches[0].len = matchlen; + if (defermatch.len > 0) { + if (matches[0].len > defermatch.len + 1) { + /* We have a better match. Emit the deferred char, + * and defer this match. */ + ctx->literal(ctx, (unsigned char) deferchr); + defermatch = matches[0]; + deferchr = data[0]; + advance = 1; + } else { + /* We don't have a better match. Do the deferred one. */ + ctx->match(ctx, defermatch.distance, defermatch.len); + advance = defermatch.len - 1; + defermatch.len = 0; + } + } else { + /* There was no deferred match. Defer this one. */ + defermatch = matches[0]; + deferchr = data[0]; + advance = 1; + } + } else { + /* + * We found no matches. Emit the deferred match, if + * any; otherwise emit a literal. + */ + if (defermatch.len > 0) { + ctx->match(ctx, defermatch.distance, defermatch.len); + advance = defermatch.len - 1; + defermatch.len = 0; + } else { + ctx->literal(ctx, data[0]); + advance = 1; + } + } + + /* + * Now advance the position by `advance' characters, + * keeping the window and hash chains consistent. + */ + while (advance > 0) { + if (len >= HASHCHARS) { + lz77_advance(st, *data, lz77_hash(data)); + } else { + st->pending[st->npending++] = *data; + } + data++; + len--; + advance--; + } + } +} + +/* ---------------------------------------------------------------------- + * Deflate functionality common to both compression and decompression. + */ + +static const unsigned char lenlenmap[] = { + 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 +}; + +#define MAXCODELEN 16 + +/* + * Given a sequence of Huffman code lengths, compute the actual + * codes, in the final form suitable for feeding to outbits (i.e. + * already bit-mirrored). + * + * Returns the maximum code length found. Can also return -1 to + * indicate the table was overcommitted (too many or too short + * codes to exactly cover the possible space), or -2 to indicate it + * was undercommitted (too few or too long codes). + */ +static int hufcodes(const unsigned char *lengths, int *codes, int nsyms) +{ + int count[MAXCODELEN], startcode[MAXCODELEN]; + int code, maxlen; + int i, j; + + /* Count the codes of each length. */ + maxlen = 0; + for (i = 1; i < MAXCODELEN; i++) + count[i] = 0; + for (i = 0; i < nsyms; i++) { + count[lengths[i]]++; + if (maxlen < lengths[i]) + maxlen = lengths[i]; + } + /* Determine the starting code for each length block. */ + code = 0; + for (i = 1; i < MAXCODELEN; i++) { + startcode[i] = code; + code += count[i]; + if (code > (1 << i)) + maxlen = -1; /* overcommitted */ + code <<= 1; + } + if (code < (1 << MAXCODELEN)) + maxlen = -2; /* undercommitted */ + /* Determine the code for each symbol. Mirrored, of course. */ + for (i = 0; i < nsyms; i++) { + code = startcode[lengths[i]]++; + codes[i] = 0; + for (j = 0; j < lengths[i]; j++) { + codes[i] = (codes[i] << 1) | (code & 1); + code >>= 1; + } + } + + return maxlen; +} + +/* + * Adler32 checksum function. + */ +static unsigned long adler32_update(unsigned long s, + const unsigned char *data, int len) +{ + unsigned s1 = s & 0xFFFF, s2 = (s >> 16) & 0xFFFF; + int i; + + for (i = 0; i < len; i++) { + s1 += data[i]; + s2 += s1; + if (!(i & 0xFFF)) { + s1 %= 65521; + s2 %= 65521; + } + } + + return ((s2 % 65521) << 16) | (s1 % 65521); +} + +/* + * CRC32 checksum function. + */ + +static unsigned long crc32_update(unsigned long crcword, + const unsigned char *data, int len) +{ + static const unsigned long crc32_table[256] = { + 0x00000000L, 0x77073096L, 0xEE0E612CL, 0x990951BAL, + 0x076DC419L, 0x706AF48FL, 0xE963A535L, 0x9E6495A3L, + 0x0EDB8832L, 0x79DCB8A4L, 0xE0D5E91EL, 0x97D2D988L, + 0x09B64C2BL, 0x7EB17CBDL, 0xE7B82D07L, 0x90BF1D91L, + 0x1DB71064L, 0x6AB020F2L, 0xF3B97148L, 0x84BE41DEL, + 0x1ADAD47DL, 0x6DDDE4EBL, 0xF4D4B551L, 0x83D385C7L, + 0x136C9856L, 0x646BA8C0L, 0xFD62F97AL, 0x8A65C9ECL, + 0x14015C4FL, 0x63066CD9L, 0xFA0F3D63L, 0x8D080DF5L, + 0x3B6E20C8L, 0x4C69105EL, 0xD56041E4L, 0xA2677172L, + 0x3C03E4D1L, 0x4B04D447L, 0xD20D85FDL, 0xA50AB56BL, + 0x35B5A8FAL, 0x42B2986CL, 0xDBBBC9D6L, 0xACBCF940L, + 0x32D86CE3L, 0x45DF5C75L, 0xDCD60DCFL, 0xABD13D59L, + 0x26D930ACL, 0x51DE003AL, 0xC8D75180L, 0xBFD06116L, + 0x21B4F4B5L, 0x56B3C423L, 0xCFBA9599L, 0xB8BDA50FL, + 0x2802B89EL, 0x5F058808L, 0xC60CD9B2L, 0xB10BE924L, + 0x2F6F7C87L, 0x58684C11L, 0xC1611DABL, 0xB6662D3DL, + 0x76DC4190L, 0x01DB7106L, 0x98D220BCL, 0xEFD5102AL, + 0x71B18589L, 0x06B6B51FL, 0x9FBFE4A5L, 0xE8B8D433L, + 0x7807C9A2L, 0x0F00F934L, 0x9609A88EL, 0xE10E9818L, + 0x7F6A0DBBL, 0x086D3D2DL, 0x91646C97L, 0xE6635C01L, + 0x6B6B51F4L, 0x1C6C6162L, 0x856530D8L, 0xF262004EL, + 0x6C0695EDL, 0x1B01A57BL, 0x8208F4C1L, 0xF50FC457L, + 0x65B0D9C6L, 0x12B7E950L, 0x8BBEB8EAL, 0xFCB9887CL, + 0x62DD1DDFL, 0x15DA2D49L, 0x8CD37CF3L, 0xFBD44C65L, + 0x4DB26158L, 0x3AB551CEL, 0xA3BC0074L, 0xD4BB30E2L, + 0x4ADFA541L, 0x3DD895D7L, 0xA4D1C46DL, 0xD3D6F4FBL, + 0x4369E96AL, 0x346ED9FCL, 0xAD678846L, 0xDA60B8D0L, + 0x44042D73L, 0x33031DE5L, 0xAA0A4C5FL, 0xDD0D7CC9L, + 0x5005713CL, 0x270241AAL, 0xBE0B1010L, 0xC90C2086L, + 0x5768B525L, 0x206F85B3L, 0xB966D409L, 0xCE61E49FL, + 0x5EDEF90EL, 0x29D9C998L, 0xB0D09822L, 0xC7D7A8B4L, + 0x59B33D17L, 0x2EB40D81L, 0xB7BD5C3BL, 0xC0BA6CADL, + 0xEDB88320L, 0x9ABFB3B6L, 0x03B6E20CL, 0x74B1D29AL, + 0xEAD54739L, 0x9DD277AFL, 0x04DB2615L, 0x73DC1683L, + 0xE3630B12L, 0x94643B84L, 0x0D6D6A3EL, 0x7A6A5AA8L, + 0xE40ECF0BL, 0x9309FF9DL, 0x0A00AE27L, 0x7D079EB1L, + 0xF00F9344L, 0x8708A3D2L, 0x1E01F268L, 0x6906C2FEL, + 0xF762575DL, 0x806567CBL, 0x196C3671L, 0x6E6B06E7L, + 0xFED41B76L, 0x89D32BE0L, 0x10DA7A5AL, 0x67DD4ACCL, + 0xF9B9DF6FL, 0x8EBEEFF9L, 0x17B7BE43L, 0x60B08ED5L, + 0xD6D6A3E8L, 0xA1D1937EL, 0x38D8C2C4L, 0x4FDFF252L, + 0xD1BB67F1L, 0xA6BC5767L, 0x3FB506DDL, 0x48B2364BL, + 0xD80D2BDAL, 0xAF0A1B4CL, 0x36034AF6L, 0x41047A60L, + 0xDF60EFC3L, 0xA867DF55L, 0x316E8EEFL, 0x4669BE79L, + 0xCB61B38CL, 0xBC66831AL, 0x256FD2A0L, 0x5268E236L, + 0xCC0C7795L, 0xBB0B4703L, 0x220216B9L, 0x5505262FL, + 0xC5BA3BBEL, 0xB2BD0B28L, 0x2BB45A92L, 0x5CB36A04L, + 0xC2D7FFA7L, 0xB5D0CF31L, 0x2CD99E8BL, 0x5BDEAE1DL, + 0x9B64C2B0L, 0xEC63F226L, 0x756AA39CL, 0x026D930AL, + 0x9C0906A9L, 0xEB0E363FL, 0x72076785L, 0x05005713L, + 0x95BF4A82L, 0xE2B87A14L, 0x7BB12BAEL, 0x0CB61B38L, + 0x92D28E9BL, 0xE5D5BE0DL, 0x7CDCEFB7L, 0x0BDBDF21L, + 0x86D3D2D4L, 0xF1D4E242L, 0x68DDB3F8L, 0x1FDA836EL, + 0x81BE16CDL, 0xF6B9265BL, 0x6FB077E1L, 0x18B74777L, + 0x88085AE6L, 0xFF0F6A70L, 0x66063BCAL, 0x11010B5CL, + 0x8F659EFFL, 0xF862AE69L, 0x616BFFD3L, 0x166CCF45L, + 0xA00AE278L, 0xD70DD2EEL, 0x4E048354L, 0x3903B3C2L, + 0xA7672661L, 0xD06016F7L, 0x4969474DL, 0x3E6E77DBL, + 0xAED16A4AL, 0xD9D65ADCL, 0x40DF0B66L, 0x37D83BF0L, + 0xA9BCAE53L, 0xDEBB9EC5L, 0x47B2CF7FL, 0x30B5FFE9L, + 0xBDBDF21CL, 0xCABAC28AL, 0x53B39330L, 0x24B4A3A6L, + 0xBAD03605L, 0xCDD70693L, 0x54DE5729L, 0x23D967BFL, + 0xB3667A2EL, 0xC4614AB8L, 0x5D681B02L, 0x2A6F2B94L, + 0xB40BBE37L, 0xC30C8EA1L, 0x5A05DF1BL, 0x2D02EF8DL + }; + crcword ^= 0xFFFFFFFFL; + while (len--) { + unsigned long newbyte = *data++; + newbyte ^= crcword & 0xFFL; + crcword = (crcword >> 8) ^ crc32_table[newbyte]; + } + return crcword ^ 0xFFFFFFFFL; +} + +typedef struct { + short code, extrabits; + int min, max; +} coderecord; + +static const coderecord lencodes[] = { + {257, 0, 3, 3}, + {258, 0, 4, 4}, + {259, 0, 5, 5}, + {260, 0, 6, 6}, + {261, 0, 7, 7}, + {262, 0, 8, 8}, + {263, 0, 9, 9}, + {264, 0, 10, 10}, + {265, 1, 11, 12}, + {266, 1, 13, 14}, + {267, 1, 15, 16}, + {268, 1, 17, 18}, + {269, 2, 19, 22}, + {270, 2, 23, 26}, + {271, 2, 27, 30}, + {272, 2, 31, 34}, + {273, 3, 35, 42}, + {274, 3, 43, 50}, + {275, 3, 51, 58}, + {276, 3, 59, 66}, + {277, 4, 67, 82}, + {278, 4, 83, 98}, + {279, 4, 99, 114}, + {280, 4, 115, 130}, + {281, 5, 131, 162}, + {282, 5, 163, 194}, + {283, 5, 195, 226}, + {284, 5, 227, 257}, + {285, 0, 258, 258}, +}; + +static const coderecord distcodes[] = { + {0, 0, 1, 1}, + {1, 0, 2, 2}, + {2, 0, 3, 3}, + {3, 0, 4, 4}, + {4, 1, 5, 6}, + {5, 1, 7, 8}, + {6, 2, 9, 12}, + {7, 2, 13, 16}, + {8, 3, 17, 24}, + {9, 3, 25, 32}, + {10, 4, 33, 48}, + {11, 4, 49, 64}, + {12, 5, 65, 96}, + {13, 5, 97, 128}, + {14, 6, 129, 192}, + {15, 6, 193, 256}, + {16, 7, 257, 384}, + {17, 7, 385, 512}, + {18, 8, 513, 768}, + {19, 8, 769, 1024}, + {20, 9, 1025, 1536}, + {21, 9, 1537, 2048}, + {22, 10, 2049, 3072}, + {23, 10, 3073, 4096}, + {24, 11, 4097, 6144}, + {25, 11, 6145, 8192}, + {26, 12, 8193, 12288}, + {27, 12, 12289, 16384}, + {28, 13, 16385, 24576}, + {29, 13, 24577, 32768}, +}; + +/* ---------------------------------------------------------------------- + * Deflate compression. + */ + +#define SYMLIMIT 65536 +#define SYMPFX_LITLEN 0x00000000U +#define SYMPFX_DIST 0x40000000U +#define SYMPFX_EXTRABITS 0x80000000U +#define SYMPFX_CODELEN 0xC0000000U +#define SYMPFX_MASK 0xC0000000U + +#define SYM_EXTRABITS_MASK 0x3C000000U +#define SYM_EXTRABITS_SHIFT 26 + +struct huftrees { + unsigned char *len_litlen; + int *code_litlen; + unsigned char *len_dist; + int *code_dist; + unsigned char *len_codelen; + int *code_codelen; +}; + +struct deflate_compress_ctx { + struct LZ77Context *lzc; + unsigned char *outbuf; + int outlen, outsize; + unsigned long outbits; + int noutbits; + int firstblock; + unsigned long *syms; + int symstart, nsyms; + int type; + unsigned long checksum; + unsigned long datasize; + int lastblock; + int finished; + unsigned char static_len1[286], static_len2[30]; + int static_code1[286], static_code2[30]; + struct huftrees sht; +#ifdef STATISTICS + unsigned long bitcount; +#endif +}; + +static void outbits(deflate_compress_ctx *out, + unsigned long bits, int nbits) +{ + assert(out->noutbits + nbits <= 32); + out->outbits |= bits << out->noutbits; + out->noutbits += nbits; + while (out->noutbits >= 8) { + if (out->outlen >= out->outsize) { + out->outsize = out->outlen + 64; + out->outbuf = sresize(out->outbuf, out->outsize, unsigned char); + } + out->outbuf[out->outlen++] = (unsigned char) (out->outbits & 0xFF); + out->outbits >>= 8; + out->noutbits -= 8; + } +#ifdef STATISTICS + out->bitcount += nbits; +#endif +} + +/* + * Binary heap functions used by buildhuf(). Each one assumes the + * heap to be stored in an array of ints, with two ints per node + * (user data and key). They take in the old heap length, and + * return the new one. + */ +#define HEAPPARENT(x) (((x)-2)/4*2) +#define HEAPLEFT(x) ((x)*2+2) +#define HEAPRIGHT(x) ((x)*2+4) +static int addheap(int *heap, int len, int userdata, int key) +{ + int me, dad, tmp; + + me = len; + heap[len++] = userdata; + heap[len++] = key; + + while (me > 0) { + dad = HEAPPARENT(me); + if (heap[me+1] < heap[dad+1]) { + tmp = heap[me]; heap[me] = heap[dad]; heap[dad] = tmp; + tmp = heap[me+1]; heap[me+1] = heap[dad+1]; heap[dad+1] = tmp; + me = dad; + } else + break; + } + + return len; +} +static int rmheap(int *heap, int len, int *userdata, int *key) +{ + int me, lc, rc, c, tmp; + + len -= 2; + *userdata = heap[0]; + *key = heap[1]; + heap[0] = heap[len]; + heap[1] = heap[len+1]; + + me = 0; + + while (1) { + lc = HEAPLEFT(me); + rc = HEAPRIGHT(me); + if (lc >= len) + break; + else if (rc >= len || heap[lc+1] < heap[rc+1]) + c = lc; + else + c = rc; + if (heap[me+1] > heap[c+1]) { + tmp = heap[me]; heap[me] = heap[c]; heap[c] = tmp; + tmp = heap[me+1]; heap[me+1] = heap[c+1]; heap[c+1] = tmp; + } else + break; + me = c; + } + + return len; +} + +/* + * The core of the Huffman algorithm: takes an input array of + * symbol frequencies, and produces an output array of code + * lengths. + * + * This is basically a generic Huffman implementation, but it has + * one zlib-related quirk which is that it caps the output code + * lengths to fit in an unsigned char (which is safe since Deflate + * will reject anything longer than 15 anyway). Anyone wanting to + * rip it out and use it in another context should find that easy + * to remove. + */ +#define HUFMAX 286 +static void buildhuf(const int *freqs, unsigned char *lengths, int nsyms) +{ + int parent[2*HUFMAX-1]; + int length[2*HUFMAX-1]; + int heap[2*HUFMAX]; + int heapsize; + int i, j, n; + int si, sj; + + assert(nsyms <= HUFMAX); + + memset(parent, 0, sizeof(parent)); + + /* + * Begin by building the heap. + */ + heapsize = 0; + for (i = 0; i < nsyms; i++) + if (freqs[i] > 0) /* leave unused symbols out totally */ + heapsize = addheap(heap, heapsize, i, freqs[i]); + + /* + * Now repeatedly take two elements off the heap and merge + * them. + */ + n = HUFMAX; + while (heapsize > 2) { + heapsize = rmheap(heap, heapsize, &i, &si); + heapsize = rmheap(heap, heapsize, &j, &sj); + parent[i] = n; + parent[j] = n; + heapsize = addheap(heap, heapsize, n, si + sj); + n++; + } + + /* + * Now we have our tree, in the form of a link from each node + * to the index of its parent. Count back down the tree to + * determine the code lengths. + */ + memset(length, 0, sizeof(length)); + /* The tree root has length 0 after that, which is correct. */ + for (i = n-1; i-- ;) + if (parent[i] > 0) + length[i] = 1 + length[parent[i]]; + + /* + * And that's it. (Simple, wasn't it?) Copy the lengths into + * the output array and leave. + * + * Here we cap lengths to fit in unsigned char. + */ + for (i = 0; i < nsyms; i++) + lengths[i] = (length[i] > 255 ? 255 : length[i]); +} + +/* + * Wrapper around buildhuf() which enforces the Deflate restriction + * that no code length may exceed 15 bits, or 7 for the auxiliary + * code length alphabet. This function has the same calling + * semantics as buildhuf(), except that it might modify the freqs + * array. + */ +static void deflate_buildhuf(int *freqs, unsigned char *lengths, + int nsyms, int limit) +{ + int smallestfreq, totalfreq, nactivesyms; + int num, denom, adjust; + int i; + int maxprob; + + /* + * Nasty special case: if the frequency table has fewer than + * two non-zero elements, we must invent some, because we can't + * have fewer than one bit encoding a symbol. + */ + assert(nsyms >= 2); + { + int count = 0; + for (i = 0; i < nsyms; i++) + if (freqs[i] > 0) + count++; + if (count < 2) { + for (i = 0; i < nsyms && count > 0; i++) + if (freqs[i] == 0) { + freqs[i] = 1; + count--; + } + } + } + + /* + * First, try building the Huffman table the normal way. If + * this works, it's optimal, so we don't want to mess with it. + */ + buildhuf(freqs, lengths, nsyms); + + for (i = 0; i < nsyms; i++) + if (lengths[i] > limit) + break; + + if (i == nsyms) + return; /* OK */ + + /* + * The Huffman algorithm can only ever generate a code length + * of N bits or more if there is a symbol whose probability is + * less than the reciprocal of the (N+2)th Fibonacci number + * (counting from F_0=0 and F_1=1), i.e. 1/2584 for N=16, or + * 1/55 for N=8. (This is a necessary though not sufficient + * condition.) + * + * Why is this? Well, consider the input symbol with the + * smallest probability. Let that probability be x. In order + * for this symbol to have a code length of at least 1, the + * Huffman algorithm will have to merge it with some other + * node; and since x is the smallest probability, the node it + * gets merged with must be at least x. Thus, the probability + * of the resulting combined node will be at least 2x. Now in + * order for our node to reach depth 2, this 2x-node must be + * merged again. But what with? We can't assume the node it + * merges with is at least 2x, because this one might only be + * the _second_ smallest remaining node. But we do know the + * node it merges with must be at least x, so our order-2 + * internal node is at least 3x. + * + * How small a node can merge with _that_ to get an order-3 + * internal node? Well, it must be at least 2x, because if it + * was smaller than that then it would have been one of the two + * smallest nodes in the previous step and been merged at that + * point. So at least 3x, plus at least 2x, comes to at least + * 5x for an order-3 node. + * + * And so it goes on: at every stage we must merge our current + * node with a node at least as big as the bigger of this one's + * two parents, and from this starting point that gives rise to + * the Fibonacci sequence. So we find that in order to have a + * node n levels deep (i.e. a maximum code length of n), the + * overall probability of the root of the entire tree must be + * at least F_{n+2} times the probability of the rarest symbol. + * In other words, since the overall probability is 1, it is a + * necessary condition for a code length of 16 or more that + * there must be at least one symbol with probability <= + * 1/F_18. + * + * (To demonstrate that a probability this big really can give + * rise to a code length of 16, consider the set of input + * frequencies { 1-epsilon, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, + * 89, 144, 233, 377, 610, 987 }, for arbitrarily small + * epsilon.) + * + * So here buildhuf() has returned us an overlong code. So to + * ensure it doesn't do it again, we add a constant to all the + * (non-zero) symbol frequencies, causing them to become more + * balanced and removing the danger. We can then feed the + * results back to the standard buildhuf() and be + * assert()-level confident that the resulting code lengths + * contain nothing outside the permitted range. + */ + assert(limit == 15 || limit == 7); + maxprob = (limit == 15 ? 2584 : 55); /* no point in computing full F_n */ + totalfreq = nactivesyms = 0; + smallestfreq = -1; + for (i = 0; i < nsyms; i++) { + if (freqs[i] == 0) + continue; + if (smallestfreq < 0 || smallestfreq > freqs[i]) + smallestfreq = freqs[i]; + totalfreq += freqs[i]; + nactivesyms++; + } + assert(smallestfreq <= totalfreq / maxprob); + + /* + * We want to find the smallest integer `adjust' such that + * (totalfreq + nactivesyms * adjust) / (smallestfreq + + * adjust) is less than maxprob. A bit of algebra tells us + * that the threshold value is equal to + * + * totalfreq - maxprob * smallestfreq + * ---------------------------------- + * maxprob - nactivesyms + * + * rounded up, of course. And we'll only even be trying + * this if + */ + num = totalfreq - smallestfreq * maxprob; + denom = maxprob - nactivesyms; + adjust = (num + denom - 1) / denom; + + /* + * Now add `adjust' to all the input symbol frequencies. + */ + for (i = 0; i < nsyms; i++) + if (freqs[i] != 0) + freqs[i] += adjust; + + /* + * Rebuild the Huffman tree... + */ + buildhuf(freqs, lengths, nsyms); + + /* + * ... and this time it ought to be OK. + */ + for (i = 0; i < nsyms; i++) + assert(lengths[i] <= limit); +} + +/* + * Compute the bit length of a symbol, given the three Huffman + * trees. + */ +static int symsize(unsigned sym, const struct huftrees *trees) +{ + unsigned basesym = sym &~ SYMPFX_MASK; + + switch (sym & SYMPFX_MASK) { + case SYMPFX_LITLEN: + return trees->len_litlen[basesym]; + case SYMPFX_DIST: + return trees->len_dist[basesym]; + case SYMPFX_CODELEN: + return trees->len_codelen[basesym]; + default /*case SYMPFX_EXTRABITS*/: + return basesym >> SYM_EXTRABITS_SHIFT; + } +} + +/* + * Write out a single symbol, given the three Huffman trees. + */ +static void writesym(deflate_compress_ctx *out, + unsigned sym, const struct huftrees *trees) +{ + unsigned basesym = sym &~ SYMPFX_MASK; + int i; + + switch (sym & SYMPFX_MASK) { + case SYMPFX_LITLEN: + debug(("send: litlen %d\n", basesym)); + outbits(out, trees->code_litlen[basesym], trees->len_litlen[basesym]); + break; + case SYMPFX_DIST: + debug(("send: dist %d\n", basesym)); + outbits(out, trees->code_dist[basesym], trees->len_dist[basesym]); + break; + case SYMPFX_CODELEN: + debug(("send: codelen %d\n", basesym)); + outbits(out, trees->code_codelen[basesym],trees->len_codelen[basesym]); + break; + case SYMPFX_EXTRABITS: + i = basesym >> SYM_EXTRABITS_SHIFT; + basesym &= ~SYM_EXTRABITS_MASK; + debug(("send: extrabits %d/%d\n", basesym, i)); + outbits(out, basesym, i); + break; + } +} + +/* + * outblock() must output _either_ a dynamic block of length + * `dynamic_len', _or_ a static block of length `static_len', but + * it gets to choose which. + */ +static void outblock(deflate_compress_ctx *out, + int dynamic_len, int static_len) +{ + int freqs1[286], freqs2[30], freqs3[19]; + unsigned char len1[286], len2[30], len3[19]; + int code1[286], code2[30], code3[19]; + int hlit, hdist, hclen, bfinal, btype; + int treesrc[286 + 30]; + int treesyms[286 + 30]; + int codelen[19]; + int i, ntreesrc, ntreesyms; + int dynamic, blklen; + struct huftrees dht; + const struct huftrees *ht; +#ifdef STATISTICS + unsigned long bitcount_before; +#endif + + dht.len_litlen = len1; + dht.len_dist = len2; + dht.len_codelen = len3; + dht.code_litlen = code1; + dht.code_dist = code2; + dht.code_codelen = code3; + + /* + * We make our choice of block to output by doing all the + * detailed work to determine the exact length of each possible + * block. Then we choose the one which has fewest output bits + * per symbol. + */ + + /* + * First build the two main Huffman trees for the dynamic + * block. + */ + + /* + * Count up the frequency tables. + */ + memset(freqs1, 0, sizeof(freqs1)); + memset(freqs2, 0, sizeof(freqs2)); + freqs1[256] = 1; /* we're bound to need one EOB */ + for (i = 0; i < dynamic_len; i++) { + unsigned sym = out->syms[(out->symstart + i) % SYMLIMIT]; + + /* + * Increment the occurrence counter for this symbol, if + * it's in one of the Huffman alphabets and isn't extra + * bits. + */ + if ((sym & SYMPFX_MASK) == SYMPFX_LITLEN) { + sym &= ~SYMPFX_MASK; + assert(sym < lenof(freqs1)); + freqs1[sym]++; + } else if ((sym & SYMPFX_MASK) == SYMPFX_DIST) { + sym &= ~SYMPFX_MASK; + assert(sym < lenof(freqs2)); + freqs2[sym]++; + } + } + deflate_buildhuf(freqs1, len1, lenof(freqs1), 15); + deflate_buildhuf(freqs2, len2, lenof(freqs2), 15); + hufcodes(len1, code1, lenof(freqs1)); + hufcodes(len2, code2, lenof(freqs2)); + + /* + * Determine HLIT and HDIST. + */ + for (hlit = 286; hlit > 257 && len1[hlit-1] == 0; hlit--); + for (hdist = 30; hdist > 1 && len2[hdist-1] == 0; hdist--); + + /* + * Write out the list of symbols used to transmit the + * trees. + */ + ntreesrc = 0; + for (i = 0; i < hlit; i++) + treesrc[ntreesrc++] = len1[i]; + for (i = 0; i < hdist; i++) + treesrc[ntreesrc++] = len2[i]; + ntreesyms = 0; + for (i = 0; i < ntreesrc ;) { + int j = 1; + int k; + + /* Find length of run of the same length code. */ + while (i+j < ntreesrc && treesrc[i+j] == treesrc[i]) + j++; + + /* Encode that run as economically as we can. */ + k = j; + if (treesrc[i] == 0) { + /* + * Zero code length: we can output run codes for + * 3-138 zeroes. So if we have fewer than 3 zeroes, + * we just output literals. Otherwise, we output + * nothing but run codes, and tweak their lengths + * to make sure we aren't left with under 3 at the + * end. + */ + if (k < 3) { + while (k--) + treesyms[ntreesyms++] = 0 | SYMPFX_CODELEN; + } else { + while (k > 0) { + int rpt = (k < 138 ? k : 138); + if (rpt > k-3 && rpt < k) + rpt = k-3; + assert(rpt >= 3 && rpt <= 138); + if (rpt < 11) { + treesyms[ntreesyms++] = 17 | SYMPFX_CODELEN; + treesyms[ntreesyms++] = + (SYMPFX_EXTRABITS | (rpt - 3) | + (3 << SYM_EXTRABITS_SHIFT)); + } else { + treesyms[ntreesyms++] = 18 | SYMPFX_CODELEN; + treesyms[ntreesyms++] = + (SYMPFX_EXTRABITS | (rpt - 11) | + (7 << SYM_EXTRABITS_SHIFT)); + } + k -= rpt; + } + } + } else { + /* + * Non-zero code length: we must output the first + * one explicitly, then we can output a copy code + * for 3-6 repeats. So if we have fewer than 4 + * repeats, we _just_ output literals. Otherwise, + * we output one literal plus at least one copy + * code, and tweak the copy codes to make sure we + * aren't left with under 3 at the end. + */ + assert(treesrc[i] < 16); + treesyms[ntreesyms++] = treesrc[i] | SYMPFX_CODELEN; + k--; + if (k < 3) { + while (k--) + treesyms[ntreesyms++] = treesrc[i] | SYMPFX_CODELEN; + } else { + while (k > 0) { + int rpt = (k < 6 ? k : 6); + if (rpt > k-3 && rpt < k) + rpt = k-3; + assert(rpt >= 3 && rpt <= 6); + treesyms[ntreesyms++] = 16 | SYMPFX_CODELEN; + treesyms[ntreesyms++] = (SYMPFX_EXTRABITS | (rpt - 3) | + (2 << SYM_EXTRABITS_SHIFT)); + k -= rpt; + } + } + } + + i += j; + } + assert((unsigned)ntreesyms < lenof(treesyms)); + + /* + * Count up the frequency table for the tree-transmission + * symbols, and build the auxiliary Huffman tree for that. + */ + memset(freqs3, 0, sizeof(freqs3)); + for (i = 0; i < ntreesyms; i++) { + unsigned sym = treesyms[i]; + + /* + * Increment the occurrence counter for this symbol, if + * it's the Huffman alphabet and isn't extra bits. + */ + if ((sym & SYMPFX_MASK) == SYMPFX_CODELEN) { + sym &= ~SYMPFX_MASK; + assert(sym < lenof(freqs3)); + freqs3[sym]++; + } + } + deflate_buildhuf(freqs3, len3, lenof(freqs3), 7); + hufcodes(len3, code3, lenof(freqs3)); + + /* + * Reorder the code length codes into transmission order, and + * determine HCLEN. + */ + for (i = 0; i < 19; i++) + codelen[i] = len3[lenlenmap[i]]; + for (hclen = 19; hclen > 4 && codelen[hclen-1] == 0; hclen--); + + /* + * Now work out the exact size of both the dynamic and the + * static block, in bits. + */ + { + int ssize, dsize; + + /* + * First the dynamic block. + */ + dsize = 3 + 5 + 5 + 4; /* 3-bit header, HLIT, HDIST, HCLEN */ + dsize += 3 * hclen; /* code-length-alphabet code lengths */ + /* Code lengths */ + for (i = 0; i < ntreesyms; i++) + dsize += symsize(treesyms[i], &dht); + /* The actual block data */ + for (i = 0; i < dynamic_len; i++) { + unsigned sym = out->syms[(out->symstart + i) % SYMLIMIT]; + dsize += symsize(sym, &dht); + } + /* And the end-of-data symbol. */ + dsize += symsize(SYMPFX_LITLEN | 256, &dht); + + /* + * Now the static block. + */ + ssize = 3; /* 3-bit block header */ + /* The actual block data */ + for (i = 0; i < static_len; i++) { + unsigned sym = out->syms[(out->symstart + i) % SYMLIMIT]; + ssize += symsize(sym, &out->sht); + } + /* And the end-of-data symbol. */ + ssize += symsize(SYMPFX_LITLEN | 256, &out->sht); + + /* + * Compare the two and decide which to output. We break + * exact ties in favour of the static block, because of the + * special case in which that block has zero length. + */ + dynamic = ((double)ssize * dynamic_len > (double)dsize * static_len); + ht = dynamic ? &dht : &out->sht; + blklen = dynamic ? dynamic_len : static_len; + } + + /* + * Actually transmit the block. + */ + + /* 3-bit block header */ + bfinal = (out->lastblock ? 1 : 0); + btype = dynamic ? 2 : 1; + debug(("send: bfinal=%d btype=%d\n", bfinal, btype)); + outbits(out, bfinal, 1); + outbits(out, btype, 2); + +#ifdef STATISTICS + bitcount_before = out->bitcount; +#endif + + if (dynamic) { + /* HLIT, HDIST and HCLEN */ + debug(("send: hlit=%d hdist=%d hclen=%d\n", hlit, hdist, hclen)); + outbits(out, hlit - 257, 5); + outbits(out, hdist - 1, 5); + outbits(out, hclen - 4, 4); + + /* Code lengths for the auxiliary tree */ + for (i = 0; i < hclen; i++) { + debug(("send: lenlen %d\n", codelen[i])); + outbits(out, codelen[i], 3); + } + + /* Code lengths for the literal/length and distance trees */ + for (i = 0; i < ntreesyms; i++) + writesym(out, treesyms[i], ht); +#ifdef STATISTICS + fprintf(stderr, "total tree size %lu bits\n", + out->bitcount - bitcount_before); +#endif + } + + /* Output the actual symbols from the buffer */ + for (i = 0; i < blklen; i++) { + unsigned sym = out->syms[(out->symstart + i) % SYMLIMIT]; + writesym(out, sym, ht); + } + + /* Output the end-of-data symbol */ + writesym(out, SYMPFX_LITLEN | 256, ht); + + /* + * Remove all the just-output symbols from the symbol buffer by + * adjusting symstart and nsyms. + */ + out->symstart = (out->symstart + blklen) % SYMLIMIT; + out->nsyms -= blklen; +} + +/* + * Give the approximate log-base-2 of an input integer, measured in + * 8ths of a bit. (I.e. this computes an integer approximation to + * 8*logbase2(x).) + */ +static int approxlog2(unsigned x) +{ + int ret = 31*8; + + /* + * Binary-search to get the top bit of x up to bit 31. + */ + if (x < 0x00010000U) x <<= 16, ret -= 16*8; + if (x < 0x01000000U) x <<= 8, ret -= 8*8; + if (x < 0x10000000U) x <<= 4, ret -= 4*8; + if (x < 0x40000000U) x <<= 2, ret -= 2*8; + if (x < 0x80000000U) x <<= 1, ret -= 1*8; + + /* + * Now we know the logarithm we want is in [ret,ret+1). + * Determine the bottom three bits by checking against + * threshold values. + * + * (Each of these threshold values is 0x80000000 times an odd + * power of 2^(1/16). Therefore, this function rounds to + * nearest.) + */ + if (x <= 0xAD583EEAU) { + if (x <= 0x91C3D373U) + ret += (x <= 0x85AAC367U ? 0 : 1); + else + ret += (x <= 0x9EF53260U ? 2 : 3); + } else { + if (x <= 0xCE248C15U) + ret += (x <= 0xBD08A39FU ? 4 : 5); + else + ret += (x <= 0xE0CCDEECU ? 6 : x <= 0xF5257D15L ? 7 : 8); + } + + return ret; +} + +static void chooseblock(deflate_compress_ctx *out) +{ + int freqs1[286], freqs2[30]; + int i, len, bestlen, longestlen = 0; + int total1, total2; + int bestvfm; + + memset(freqs1, 0, sizeof(freqs1)); + memset(freqs2, 0, sizeof(freqs2)); + freqs1[256] = 1; /* we're bound to need one EOB */ + total1 = 1; + total2 = 0; + + /* + * Iterate over all possible block lengths, computing the + * entropic coding approximation to the final length at every + * stage. We divide the result by the number of symbols + * encoded, to determine the `value for money' (overall + * bits-per-symbol count) of a block of that length. + */ + bestlen = -1; + bestvfm = 0; + + len = 300 * 8; /* very approximate size of the Huffman trees */ + + for (i = 0; i < out->nsyms; i++) { + unsigned sym = out->syms[(out->symstart + i) % SYMLIMIT]; + + if (i > 0 && (sym & SYMPFX_MASK) == SYMPFX_LITLEN) { + /* + * This is a viable point at which to end the block. + * Compute the value for money. + */ + int vfm = i * 32768 / len; /* symbols encoded per bit */ + + if (bestlen < 0 || vfm > bestvfm) { + bestlen = i; + bestvfm = vfm; + } + + longestlen = i; + } + + /* + * Increment the occurrence counter for this symbol, if + * it's in one of the Huffman alphabets and isn't extra + * bits. + */ + if ((sym & SYMPFX_MASK) == SYMPFX_LITLEN) { + sym &= ~SYMPFX_MASK; + assert(sym < lenof(freqs1)); + len += freqs1[sym] * approxlog2(freqs1[sym]); + len -= total1 * approxlog2(total1); + freqs1[sym]++; + total1++; + len -= freqs1[sym] * approxlog2(freqs1[sym]); + len += total1 * approxlog2(total1); + } else if ((sym & SYMPFX_MASK) == SYMPFX_DIST) { + sym &= ~SYMPFX_MASK; + assert(sym < lenof(freqs2)); + len += freqs2[sym] * approxlog2(freqs2[sym]); + len -= total2 * approxlog2(total2); + freqs2[sym]++; + total2++; + len -= freqs2[sym] * approxlog2(freqs2[sym]); + len += total2 * approxlog2(total2); + } else if ((sym & SYMPFX_MASK) == SYMPFX_EXTRABITS) { + len += 8 * ((sym &~ SYMPFX_MASK) >> SYM_EXTRABITS_SHIFT); + } + } + + assert(bestlen > 0); + + outblock(out, bestlen, longestlen); +} + +/* + * Force the current symbol buffer to be flushed out as a single + * block. + */ +static void flushblock(deflate_compress_ctx *out) +{ + /* + * No need to check that out->nsyms is a valid block length: we + * know it has to be, because flushblock() is called in between + * two matches/literals. + */ + outblock(out, out->nsyms, out->nsyms); + assert(out->nsyms == 0); +} + +/* + * Place a symbol into the symbols buffer. + */ +static void outsym(deflate_compress_ctx *out, unsigned long sym) +{ + assert(out->nsyms < SYMLIMIT); + out->syms[(out->symstart + out->nsyms++) % SYMLIMIT] = sym; + + if (out->nsyms == SYMLIMIT) + chooseblock(out); +} + +static void literal(struct LZ77Context *ectx, unsigned char c) +{ + deflate_compress_ctx *out = (deflate_compress_ctx *) ectx->userdata; + + outsym(out, SYMPFX_LITLEN | c); +} + +static void match(struct LZ77Context *ectx, int distance, int len) +{ + const coderecord *d, *l; + int i, j, k; + deflate_compress_ctx *out = (deflate_compress_ctx *) ectx->userdata; + + while (len > 0) { + int thislen; + + /* + * We can transmit matches of lengths 3 through 258 + * inclusive. So if len exceeds 258, we must transmit in + * several steps, with 258 or less in each step. + * + * Specifically: if len >= 261, we can transmit 258 and be + * sure of having at least 3 left for the next step. And if + * len <= 258, we can just transmit len. But if len == 259 + * or 260, we must transmit len-3. + */ + thislen = (len > 260 ? 258 : len <= 258 ? len : len - 3); + len -= thislen; + + /* + * Binary-search to find which length code we're + * transmitting. + */ + i = -1; + j = sizeof(lencodes) / sizeof(*lencodes); + while (1) { + assert(j - i >= 2); + k = (j + i) / 2; + if (thislen < lencodes[k].min) + j = k; + else if (thislen > lencodes[k].max) + i = k; + else { + l = &lencodes[k]; + break; /* found it! */ + } + } + + /* + * Transmit the length code. + */ + outsym(out, SYMPFX_LITLEN | l->code); + + /* + * Transmit the extra bits. + */ + if (l->extrabits) { + outsym(out, (SYMPFX_EXTRABITS | (thislen - l->min) | + (l->extrabits << SYM_EXTRABITS_SHIFT))); + } + + /* + * Binary-search to find which distance code we're + * transmitting. + */ + i = -1; + j = sizeof(distcodes) / sizeof(*distcodes); + while (1) { + assert(j - i >= 2); + k = (j + i) / 2; + if (distance < distcodes[k].min) + j = k; + else if (distance > distcodes[k].max) + i = k; + else { + d = &distcodes[k]; + break; /* found it! */ + } + } + + /* + * Write the distance code. + */ + outsym(out, SYMPFX_DIST | d->code); + + /* + * Transmit the extra bits. + */ + if (d->extrabits) { + outsym(out, (SYMPFX_EXTRABITS | (distance - d->min) | + (d->extrabits << SYM_EXTRABITS_SHIFT))); + } + } +} + +deflate_compress_ctx *deflate_compress_new(int type) +{ + deflate_compress_ctx *out; + struct LZ77Context *ectx = snew(struct LZ77Context); + + lz77_init(ectx); + ectx->literal = literal; + ectx->match = match; + + out = snew(deflate_compress_ctx); + out->type = type; + out->outbits = out->noutbits = 0; + out->firstblock = TRUE; +#ifdef STATISTICS + out->bitcount = 0; +#endif + + out->syms = snewn(SYMLIMIT, unsigned long); + out->symstart = out->nsyms = 0; + + out->checksum = (type == DEFLATE_TYPE_ZLIB ? 1 : 0); + out->datasize = 0; + out->lastblock = FALSE; + out->finished = FALSE; + + /* + * Build the static Huffman tables now, so we'll have them + * available every time outblock() is called. + */ + { + int i; + + for (i = 0; i < lenof(out->static_len1); i++) + out->static_len1[i] = (i < 144 ? 8 : + i < 256 ? 9 : + i < 280 ? 7 : 8); + for (i = 0; i < lenof(out->static_len2); i++) + out->static_len2[i] = 5; + } + hufcodes(out->static_len1, out->static_code1, lenof(out->static_code1)); + hufcodes(out->static_len2, out->static_code2, lenof(out->static_code2)); + out->sht.len_litlen = out->static_len1; + out->sht.len_dist = out->static_len2; + out->sht.len_codelen = NULL; + out->sht.code_litlen = out->static_code1; + out->sht.code_dist = out->static_code2; + out->sht.code_codelen = NULL; + + ectx->userdata = out; + out->lzc = ectx; + + return out; +} + +void deflate_compress_free(deflate_compress_ctx *out) +{ + struct LZ77Context *ectx = out->lzc; + + sfree(out->syms); + sfree(ectx->ictx); + sfree(ectx); + sfree(out); +} + +void deflate_compress_data(deflate_compress_ctx *out, + const void *vblock, int len, int flushtype, + void **outblock, int *outlen) +{ + struct LZ77Context *ectx = out->lzc; + const unsigned char *block = (const unsigned char *)vblock; + + assert(!out->finished); + + out->outbuf = NULL; + out->outlen = out->outsize = 0; + + /* + * If this is the first block, output the header. + */ + if (out->firstblock) { + switch (out->type) { + case DEFLATE_TYPE_BARE: + break; /* no header */ + case DEFLATE_TYPE_ZLIB: + /* + * zlib (RFC1950) header bytes: 78 9C. (Deflate + * compression, 32K window size, default algorithm.) + */ + outbits(out, 0x9C78, 16); + break; + case DEFLATE_TYPE_GZIP: + /* + * Minimal gzip (RFC1952) header: + * + * - basic header of 1F 8B + * - compression method byte (8 = deflate) + * - flags byte (zero: we use no optional features) + * - modification time (zero: no time stamp available) + * - extra flags byte (2: we use maximum compression + * always) + * - operating system byte (255: we do not specify) + */ + outbits(out, 0x00088B1F, 32); /* header, CM, flags */ + outbits(out, 0, 32); /* mtime */ + outbits(out, 0xFF02, 16); /* xflags, OS */ + break; + } + out->firstblock = FALSE; + } + + /* + * Feed our data to the LZ77 compression phase. + */ + lz77_compress(ectx, block, len, TRUE); + + /* + * Update checksums and counters. + */ + switch (out->type) { + case DEFLATE_TYPE_ZLIB: + out->checksum = adler32_update(out->checksum, block, len); + break; + case DEFLATE_TYPE_GZIP: + out->checksum = crc32_update(out->checksum, block, len); + break; + } + out->datasize += len; + + switch (flushtype) { + /* + * FIXME: what other flush types are available and useful? + * In PuTTY, it was clear that we generally wanted to be in + * a static block so it was safe to open one. Here, we + * probably prefer to be _outside_ a block if we can. Think + * about this. + */ + case DEFLATE_NO_FLUSH: + break; /* don't flush any data at all (duh) */ + case DEFLATE_SYNC_FLUSH: + /* + * Close the current block. + */ + flushblock(out); + + /* + * Then output an empty _uncompressed_ block: send 000, + * then sync to byte boundary, then send bytes 00 00 FF + * FF. + */ + outbits(out, 0, 3); + if (out->noutbits) + outbits(out, 0, 8 - out->noutbits); + outbits(out, 0, 16); + outbits(out, 0xFFFF, 16); + break; + case DEFLATE_END_OF_DATA: + /* + * Output a block with BFINAL set. + */ + out->lastblock = TRUE; + flushblock(out); + + /* + * Sync to byte boundary, flushing out the final byte. + */ + if (out->noutbits) + outbits(out, 0, 8 - out->noutbits); + + /* + * Format-specific trailer data. + */ + switch (out->type) { + case DEFLATE_TYPE_ZLIB: + /* + * Just write out the Adler32 checksum. + */ + outbits(out, (out->checksum >> 24) & 0xFF, 8); + outbits(out, (out->checksum >> 16) & 0xFF, 8); + outbits(out, (out->checksum >> 8) & 0xFF, 8); + outbits(out, (out->checksum >> 0) & 0xFF, 8); + break; + case DEFLATE_TYPE_GZIP: + /* + * Write out the CRC32 checksum and the data length. + */ + outbits(out, out->checksum, 32); + outbits(out, out->datasize, 32); + break; + } + + out->finished = TRUE; + break; + } + + /* + * Return any data that we've generated. + */ + *outblock = (void *)out->outbuf; + *outlen = out->outlen; +} + +/* ---------------------------------------------------------------------- + * Deflate decompression. + */ + +/* + * The way we work the Huffman decode is to have a table lookup on + * the first N bits of the input stream (in the order they arrive, + * of course, i.e. the first bit of the Huffman code is in bit 0). + * Each table entry lists the number of bits to consume, plus + * either an output code or a pointer to a secondary table. + */ +struct table; +struct tableentry; + +struct tableentry { + unsigned char nbits; + short code; + struct table *nexttable; +}; + +struct table { + int mask; /* mask applied to input bit stream */ + struct tableentry *table; +}; + +#define MAXSYMS 288 + +#define DWINSIZE 32768 + +/* + * Build a single-level decode table for elements + * [minlength,maxlength) of the provided code/length tables, and + * recurse to build subtables. + */ +static struct table *mkonetab(int *codes, unsigned char *lengths, int nsyms, + int pfx, int pfxbits, int bits) +{ + struct table *tab = snew(struct table); + int pfxmask = (1 << pfxbits) - 1; + int nbits, i, j, code; + + tab->table = snewn(1 << bits, struct tableentry); + tab->mask = (1 << bits) - 1; + + for (code = 0; code <= tab->mask; code++) { + tab->table[code].code = -1; + tab->table[code].nbits = 0; + tab->table[code].nexttable = NULL; + } + + for (i = 0; i < nsyms; i++) { + if (lengths[i] <= pfxbits || (codes[i] & pfxmask) != pfx) + continue; + code = (codes[i] >> pfxbits) & tab->mask; + for (j = code; j <= tab->mask; j += 1 << (lengths[i] - pfxbits)) { + tab->table[j].code = i; + nbits = lengths[i] - pfxbits; + if (tab->table[j].nbits < nbits) + tab->table[j].nbits = nbits; + } + } + for (code = 0; code <= tab->mask; code++) { + if (tab->table[code].nbits <= bits) + continue; + /* Generate a subtable. */ + tab->table[code].code = -1; + nbits = tab->table[code].nbits - bits; + if (nbits > 7) + nbits = 7; + tab->table[code].nbits = bits; + tab->table[code].nexttable = mkonetab(codes, lengths, nsyms, + pfx | (code << pfxbits), + pfxbits + bits, nbits); + } + + return tab; +} + +/* + * Build a decode table, given a set of Huffman tree lengths. + */ +static struct table *mktable(unsigned char *lengths, int nlengths, +#ifdef ANALYSIS + const char *alphabet, +#endif + int *error) +{ + int codes[MAXSYMS]; + int maxlen; + +#ifdef ANALYSIS + if (alphabet && analyse_level > 1) { + int i, col = 0; + printf("code lengths for %s alphabet:\n", alphabet); + for (i = 0; i < nlengths; i++) { + col += printf("%3d", lengths[i]); + if (col > 72) { + putchar('\n'); + col = 0; + } + } + if (col > 0) + putchar('\n'); + } +#endif + + maxlen = hufcodes(lengths, codes, nlengths); + + if (maxlen < 0) { + *error = (maxlen == -1 ? DEFLATE_ERR_LARGE_HUFTABLE : + DEFLATE_ERR_SMALL_HUFTABLE); + return NULL; + } + + /* + * Now we have the complete list of Huffman codes. Build a + * table. + */ + return mkonetab(codes, lengths, nlengths, 0, 0, maxlen < 9 ? maxlen : 9); +} + +static int freetable(struct table **ztab) +{ + struct table *tab; + int code; + + if (ztab == NULL) + return -1; + + if (*ztab == NULL) + return 0; + + tab = *ztab; + + for (code = 0; code <= tab->mask; code++) + if (tab->table[code].nexttable != NULL) + freetable(&tab->table[code].nexttable); + + sfree(tab->table); + tab->table = NULL; + + sfree(tab); + *ztab = NULL; + + return (0); +} + +struct deflate_decompress_ctx { + struct table *staticlentable, *staticdisttable; + struct table *currlentable, *currdisttable, *lenlentable; + enum { + ZLIBSTART, + GZIPSTART, GZIPMETHFLAGS, GZIPIGNORE1, GZIPIGNORE2, GZIPIGNORE3, + GZIPEXTRA, GZIPFNAME, GZIPCOMMENT, + OUTSIDEBLK, TREES_HDR, TREES_LENLEN, TREES_LEN, TREES_LENREP, + INBLK, GOTLENSYM, GOTLEN, GOTDISTSYM, + UNCOMP_LEN, UNCOMP_NLEN, UNCOMP_DATA, + END, + ADLER1, ADLER2, + CRC1, CRC2, ILEN1, ILEN2, + FINALSPIN + } state; + int sym, hlit, hdist, hclen, lenptr, lenextrabits, lenaddon, len, + lenrep, lastblock; + int uncomplen; + unsigned char lenlen[19]; + unsigned char lengths[286 + 32]; + unsigned long bits; + int nbits; + unsigned char window[DWINSIZE]; + int winpos; + unsigned char *outblk; + int outlen, outsize; + int type; + unsigned long checksum; + unsigned long bytesout; + int gzflags, gzextralen; +#ifdef ANALYSIS + int bytesread; + int bitcount_before; +#define BITCOUNT(dctx) ( (dctx)->bytesread * 8 - (dctx)->nbits ) +#endif +}; + +deflate_decompress_ctx *deflate_decompress_new(int type) +{ + deflate_decompress_ctx *dctx = snew(deflate_decompress_ctx); + unsigned char lengths[288]; + + memset(lengths, 8, 144); + memset(lengths + 144, 9, 256 - 144); + memset(lengths + 256, 7, 280 - 256); + memset(lengths + 280, 8, 288 - 280); + dctx->staticlentable = mktable(lengths, 288, +#ifdef ANALYSIS + NULL, +#endif + NULL); + assert(dctx->staticlentable); + memset(lengths, 5, 32); + dctx->staticdisttable = mktable(lengths, 32, +#ifdef ANALYSIS + NULL, +#endif + NULL); + assert(dctx->staticdisttable); + dctx->state = (type == DEFLATE_TYPE_ZLIB ? ZLIBSTART : + type == DEFLATE_TYPE_GZIP ? GZIPSTART : + OUTSIDEBLK); + dctx->currlentable = dctx->currdisttable = dctx->lenlentable = NULL; + dctx->bits = 0; + dctx->nbits = 0; + dctx->winpos = 0; + dctx->type = type; + dctx->lastblock = FALSE; + dctx->checksum = (type == DEFLATE_TYPE_ZLIB ? 1 : 0); + dctx->bytesout = 0; + dctx->gzflags = dctx->gzextralen = 0; +#ifdef ANALYSIS + dctx->bytesread = dctx->bitcount_before = 0; +#endif + + return dctx; +} + +void deflate_decompress_free(deflate_decompress_ctx *dctx) +{ + if (dctx->currlentable && dctx->currlentable != dctx->staticlentable) + freetable(&dctx->currlentable); + if (dctx->currdisttable && dctx->currdisttable != dctx->staticdisttable) + freetable(&dctx->currdisttable); + if (dctx->lenlentable) + freetable(&dctx->lenlentable); + freetable(&dctx->staticlentable); + freetable(&dctx->staticdisttable); + sfree(dctx); +} + +static int huflookup(unsigned long *bitsp, int *nbitsp, struct table *tab) +{ + unsigned long bits = *bitsp; + int nbits = *nbitsp; + while (1) { + struct tableentry *ent; + ent = &tab->table[bits & tab->mask]; + if (ent->nbits > nbits) + return -1; /* not enough data */ + bits >>= ent->nbits; + nbits -= ent->nbits; + if (ent->code == -1) + tab = ent->nexttable; + else { + *bitsp = bits; + *nbitsp = nbits; + return ent->code; + } + + /* + * If we reach here with `tab' null, it can only be because + * there was a missing entry in the Huffman table. This + * should never occur even with invalid input data, because + * we enforce at mktable time that the Huffman codes should + * precisely cover the code space; so we can enforce this + * by assertion. + */ + assert(tab); + } +} + +static void emit_char(deflate_decompress_ctx *dctx, int c) +{ + dctx->window[dctx->winpos] = c; + dctx->winpos = (dctx->winpos + 1) & (DWINSIZE - 1); + if (dctx->outlen >= dctx->outsize) { + dctx->outsize = dctx->outlen * 3 / 2 + 512; + dctx->outblk = sresize(dctx->outblk, dctx->outsize, unsigned char); + } + if (dctx->type == DEFLATE_TYPE_ZLIB) { + unsigned char uc = c; + dctx->checksum = adler32_update(dctx->checksum, &uc, 1); + } else if (dctx->type == DEFLATE_TYPE_GZIP) { + unsigned char uc = c; + dctx->checksum = crc32_update(dctx->checksum, &uc, 1); + } + dctx->outblk[dctx->outlen++] = c; + dctx->bytesout++; +} + +#define EATBITS(n) ( dctx->nbits -= (n), dctx->bits >>= (n) ) + +int deflate_decompress_data(deflate_decompress_ctx *dctx, + const void *vblock, int len, + void **outblock, int *outlen) +{ + const coderecord *rec; + const unsigned char *block = (const unsigned char *)vblock; + int code, bfinal, btype, rep, dist, nlen, header, cksum; + int error = 0; + + if (len == 0) { + *outblock = NULL; + *outlen = 0; + if (dctx->state != FINALSPIN) + return DEFLATE_ERR_UNEXPECTED_EOF; + else + return 0; + } + + dctx->outblk = NULL; + dctx->outsize = 0; + dctx->outlen = 0; + + while (len > 0 || dctx->nbits > 0) { + while (dctx->nbits < 24 && len > 0) { + dctx->bits |= (*block++) << dctx->nbits; + dctx->nbits += 8; + len--; +#ifdef ANALYSIS + dctx->bytesread++; +#endif + } + switch (dctx->state) { + case ZLIBSTART: + /* Expect 16-bit zlib header. */ + if (dctx->nbits < 16) + goto finished; /* done all we can */ + + /* + * The header is stored as a big-endian 16-bit integer, + * in contrast to the general little-endian policy in + * the rest of the format :-( + */ + header = (((dctx->bits & 0xFF00) >> 8) | + ((dctx->bits & 0x00FF) << 8)); + EATBITS(16); + + /* + * Check the header: + * + * - bits 8-11 should be 1000 (Deflate/RFC1951) + * - bits 12-15 should be at most 0111 (window size) + * - bit 5 should be zero (no dictionary present) + * - we don't care about bits 6-7 (compression rate) + * - bits 0-4 should be set up to make the whole thing + * a multiple of 31 (checksum). + */ + if ((header & 0xF000) > 0x7000 || + (header & 0x0020) != 0x0000 || + (header % 31) != 0) { + error = DEFLATE_ERR_ZLIB_HEADER; + goto finished; + } + if ((header & 0x0F00) != 0x0800) { + error = DEFLATE_ERR_ZLIB_WRONGCOMP; + goto finished; + } + dctx->state = OUTSIDEBLK; + break; + case GZIPSTART: + /* Expect 16-bit gzip header. */ + if (dctx->nbits < 16) + goto finished; + header = dctx->bits & 0xFFFF; + EATBITS(16); + if (header != 0x8B1F) { + error = DEFLATE_ERR_GZIP_HEADER; + goto finished; + } + dctx->state = GZIPMETHFLAGS; + break; + case GZIPMETHFLAGS: + /* Expect gzip compression method and flags bytes. */ + if (dctx->nbits < 16) + goto finished; + header = dctx->bits & 0xFF; + EATBITS(8); + if (header != 8) { + error = DEFLATE_ERR_GZIP_WRONGCOMP; + goto finished; + } + dctx->gzflags = dctx->bits & 0xFF; + if (dctx->gzflags & 2) { + /* + * The FHCRC flag is slightly confusing. RFC1952 + * documents it as indicating the presence of a + * two-byte CRC16 of the gzip header, occurring + * just before the beginning of the Deflate stream. + * However, gzip itself (as of 1.3.5) appears to + * believe it indicates that the current gzip + * `member' is not the final one, i.e. that the + * stream is composed of multiple gzip members + * concatenated together, and furthermore gzip will + * refuse to decode any file that has it set. + * + * For this reason, I label it as `disputed' and + * also refuse to decode anything that has it set. + * I don't expect this to be a problem in practice. + */ + error = DEFLATE_ERR_GZIP_FHCRC; + goto finished; + } + EATBITS(8); + dctx->state = GZIPIGNORE1; + break; + case GZIPIGNORE1: + case GZIPIGNORE2: + case GZIPIGNORE3: + /* Expect two bytes of gzip timestamp/XFL/OS, which we ignore. */ + if (dctx->nbits < 16) + goto finished; + EATBITS(16); + if (dctx->state == GZIPIGNORE3) { + dctx->state = GZIPEXTRA; + } else + dctx->state++; /* maps IGNORE1 -> IGNORE2 -> IGNORE3 */ + break; + case GZIPEXTRA: + if (dctx->gzflags & 4) { + /* Expect two bytes of extra-length count, then that many + * extra bytes of header data, all of which we ignore. */ + if (!dctx->gzextralen) { + if (dctx->nbits < 16) + goto finished; + dctx->gzextralen = dctx->bits & 0xFFFF; + EATBITS(16); + break; + } else if (dctx->gzextralen > 0) { + if (dctx->nbits < 8) + goto finished; + EATBITS(8); + if (--dctx->gzextralen > 0) + break; + } + } + dctx->state = GZIPFNAME; + break; + case GZIPFNAME: + if (dctx->gzflags & 8) { + /* + * Expect a NUL-terminated filename. + */ + if (dctx->nbits < 8) + goto finished; + code = dctx->bits & 0xFF; + EATBITS(8); + } else + code = 0; + if (code == 0) + dctx->state = GZIPCOMMENT; + break; + case GZIPCOMMENT: + if (dctx->gzflags & 16) { + /* + * Expect a NUL-terminated filename. + */ + if (dctx->nbits < 8) + goto finished; + code = dctx->bits & 0xFF; + EATBITS(8); + } else + code = 0; + if (code == 0) + dctx->state = OUTSIDEBLK; + break; + case OUTSIDEBLK: + /* Expect 3-bit block header. */ + if (dctx->nbits < 3) + goto finished; /* done all we can */ + bfinal = dctx->bits & 1; + if (bfinal) + dctx->lastblock = TRUE; + EATBITS(1); + btype = dctx->bits & 3; + EATBITS(2); + if (btype == 0) { + int to_eat = dctx->nbits & 7; + dctx->state = UNCOMP_LEN; + EATBITS(to_eat); /* align to byte boundary */ + } else if (btype == 1) { + dctx->currlentable = dctx->staticlentable; + dctx->currdisttable = dctx->staticdisttable; + dctx->state = INBLK; + } else if (btype == 2) { + dctx->state = TREES_HDR; + } + debug(("recv: bfinal=%d btype=%d\n", bfinal, btype)); +#ifdef ANALYSIS + if (analyse_level > 1) { + static const char *const btypes[] = { + "uncompressed", "static", "dynamic", "type 3 (unknown)" + }; + printf("new block, %sfinal, %s\n", + bfinal ? "" : "not ", + btypes[btype]); + } +#endif + break; + case TREES_HDR: + /* + * Dynamic block header. Five bits of HLIT, five of + * HDIST, four of HCLEN. + */ + if (dctx->nbits < 5 + 5 + 4) + goto finished; /* done all we can */ + dctx->hlit = 257 + (dctx->bits & 31); + EATBITS(5); + dctx->hdist = 1 + (dctx->bits & 31); + EATBITS(5); + dctx->hclen = 4 + (dctx->bits & 15); + EATBITS(4); + debug(("recv: hlit=%d hdist=%d hclen=%d\n", dctx->hlit, + dctx->hdist, dctx->hclen)); +#ifdef ANALYSIS + if (analyse_level > 1) + printf("hlit=%d, hdist=%d, hclen=%d\n", + dctx->hlit, dctx->hdist, dctx->hclen); +#endif + dctx->lenptr = 0; + dctx->state = TREES_LENLEN; + memset(dctx->lenlen, 0, sizeof(dctx->lenlen)); + break; + case TREES_LENLEN: + if (dctx->nbits < 3) + goto finished; + while (dctx->lenptr < dctx->hclen && dctx->nbits >= 3) { + dctx->lenlen[lenlenmap[dctx->lenptr++]] = + (unsigned char) (dctx->bits & 7); + debug(("recv: lenlen %d\n", (unsigned char) (dctx->bits & 7))); + EATBITS(3); + } + if (dctx->lenptr == dctx->hclen) { + dctx->lenlentable = mktable(dctx->lenlen, 19, +#ifdef ANALYSIS + "code length", +#endif + &error); + if (!dctx->lenlentable) + goto finished; /* error code set up by mktable */ + dctx->state = TREES_LEN; + dctx->lenptr = 0; + } + break; + case TREES_LEN: + if (dctx->lenptr >= dctx->hlit + dctx->hdist) { + dctx->currlentable = mktable(dctx->lengths, dctx->hlit, +#ifdef ANALYSIS + "literal/length", +#endif + &error); + if (!dctx->currlentable) + goto finished; /* error code set up by mktable */ + dctx->currdisttable = mktable(dctx->lengths + dctx->hlit, + dctx->hdist, +#ifdef ANALYSIS + "distance", +#endif + &error); + if (!dctx->currdisttable) + goto finished; /* error code set up by mktable */ + freetable(&dctx->lenlentable); + dctx->lenlentable = NULL; + dctx->state = INBLK; + break; + } + code = huflookup(&dctx->bits, &dctx->nbits, dctx->lenlentable); + debug(("recv: codelen %d\n", code)); + if (code == -1) + goto finished; + if (code < 16) { +#ifdef ANALYSIS + if (analyse_level > 1) + printf("code-length %d\n", code); +#endif + dctx->lengths[dctx->lenptr++] = code; + } else { + dctx->lenextrabits = (code == 16 ? 2 : code == 17 ? 3 : 7); + dctx->lenaddon = (code == 18 ? 11 : 3); + dctx->lenrep = (code == 16 && dctx->lenptr > 0 ? + dctx->lengths[dctx->lenptr - 1] : 0); + dctx->state = TREES_LENREP; + } + break; + case TREES_LENREP: + if (dctx->nbits < dctx->lenextrabits) + goto finished; + rep = + dctx->lenaddon + + (dctx->bits & ((1 << dctx->lenextrabits) - 1)); + EATBITS(dctx->lenextrabits); + if (dctx->lenextrabits) + debug(("recv: codelen-extrabits %d/%d\n", rep - dctx->lenaddon, + dctx->lenextrabits)); +#ifdef ANALYSIS + if (analyse_level > 1) + printf("code-length-repeat: %d copies of %d\n", rep, + dctx->lenrep); +#endif + while (rep > 0 && dctx->lenptr < dctx->hlit + dctx->hdist) { + dctx->lengths[dctx->lenptr] = dctx->lenrep; + dctx->lenptr++; + rep--; + } + dctx->state = TREES_LEN; + break; + case INBLK: +#ifdef ANALYSIS + dctx->bitcount_before = BITCOUNT(dctx); +#endif + code = huflookup(&dctx->bits, &dctx->nbits, dctx->currlentable); + debug(("recv: litlen %d\n", code)); + if (code == -1) + goto finished; + if (code < 256) { +#ifdef ANALYSIS + if (analyse_level > 0) + printf("%lu: literal %d [%d]\n", dctx->bytesout, code, + BITCOUNT(dctx) - dctx->bitcount_before); +#endif + emit_char(dctx, code); + } else if (code == 256) { + if (dctx->lastblock) + dctx->state = END; + else + dctx->state = OUTSIDEBLK; + if (dctx->currlentable != dctx->staticlentable) { + freetable(&dctx->currlentable); + dctx->currlentable = NULL; + } + if (dctx->currdisttable != dctx->staticdisttable) { + freetable(&dctx->currdisttable); + dctx->currdisttable = NULL; + } + } else if (code < 286) { /* static tree can give >285; ignore */ + dctx->state = GOTLENSYM; + dctx->sym = code; + } + break; + case GOTLENSYM: + rec = &lencodes[dctx->sym - 257]; + if (dctx->nbits < rec->extrabits) + goto finished; + dctx->len = + rec->min + (dctx->bits & ((1 << rec->extrabits) - 1)); + if (rec->extrabits) + debug(("recv: litlen-extrabits %d/%d\n", + dctx->len - rec->min, rec->extrabits)); + EATBITS(rec->extrabits); + dctx->state = GOTLEN; + break; + case GOTLEN: + code = huflookup(&dctx->bits, &dctx->nbits, dctx->currdisttable); + debug(("recv: dist %d\n", code)); + if (code == -1) + goto finished; + dctx->state = GOTDISTSYM; + dctx->sym = code; + break; + case GOTDISTSYM: + rec = &distcodes[dctx->sym]; + if (dctx->nbits < rec->extrabits) + goto finished; + dist = rec->min + (dctx->bits & ((1 << rec->extrabits) - 1)); + if (rec->extrabits) + debug(("recv: dist-extrabits %d/%d\n", + dist - rec->min, rec->extrabits)); + EATBITS(rec->extrabits); + dctx->state = INBLK; +#ifdef ANALYSIS + if (analyse_level > 0) + printf("%lu: copy len=%d dist=%d [%d]\n", dctx->bytesout, + dctx->len, dist, + BITCOUNT(dctx) - dctx->bitcount_before); +#endif + while (dctx->len--) + emit_char(dctx, dctx->window[(dctx->winpos - dist) & + (DWINSIZE - 1)]); + break; + case UNCOMP_LEN: + /* + * Uncompressed block. We expect to see a 16-bit LEN. + */ + if (dctx->nbits < 16) + goto finished; + dctx->uncomplen = dctx->bits & 0xFFFF; + EATBITS(16); + dctx->state = UNCOMP_NLEN; + break; + case UNCOMP_NLEN: + /* + * Uncompressed block. We expect to see a 16-bit NLEN, + * which should be the one's complement of the previous + * LEN. + */ + if (dctx->nbits < 16) + goto finished; + nlen = dctx->bits & 0xFFFF; + EATBITS(16); + if (dctx->uncomplen == 0) + dctx->state = OUTSIDEBLK; /* block is empty */ + else + dctx->state = UNCOMP_DATA; + break; + case UNCOMP_DATA: + if (dctx->nbits < 8) + goto finished; +#ifdef ANALYSIS + if (analyse_level > 0) + printf("%lu: uncompressed %d [8]\n", dctx->bytesout, + (int)(dctx->bits & 0xFF)); +#endif + emit_char(dctx, dctx->bits & 0xFF); + EATBITS(8); + if (--dctx->uncomplen == 0) + dctx->state = OUTSIDEBLK; /* end of uncompressed block */ + break; + case END: + /* + * End of compressed data. We align to a byte boundary, + * and then look for format-specific trailer data. + */ + { + int to_eat = dctx->nbits & 7; + EATBITS(to_eat); + } + if (dctx->type == DEFLATE_TYPE_ZLIB) + dctx->state = ADLER1; + else if (dctx->type == DEFLATE_TYPE_GZIP) + dctx->state = CRC1; + else + dctx->state = FINALSPIN; + break; + case ADLER1: + if (dctx->nbits < 16) + goto finished; + cksum = (dctx->bits & 0xFF) << 8; + EATBITS(8); + cksum |= (dctx->bits & 0xFF); + EATBITS(8); + if (cksum != ((dctx->checksum >> 16) & 0xFFFF)) { + error = DEFLATE_ERR_CHECKSUM; + goto finished; + } + dctx->state = ADLER2; + break; + case ADLER2: + if (dctx->nbits < 16) + goto finished; + cksum = (dctx->bits & 0xFF) << 8; + EATBITS(8); + cksum |= (dctx->bits & 0xFF); + EATBITS(8); + if (cksum != (dctx->checksum & 0xFFFF)) { + error = DEFLATE_ERR_CHECKSUM; + goto finished; + } + dctx->state = FINALSPIN; + break; + case CRC1: + if (dctx->nbits < 16) + goto finished; + cksum = dctx->bits & 0xFFFF; + EATBITS(16); + if (cksum != (dctx->checksum & 0xFFFF)) { + error = DEFLATE_ERR_CHECKSUM; + goto finished; + } + dctx->state = CRC2; + break; + case CRC2: + if (dctx->nbits < 16) + goto finished; + cksum = dctx->bits & 0xFFFF; + EATBITS(16); + if (cksum != ((dctx->checksum >> 16) & 0xFFFF)) { + error = DEFLATE_ERR_CHECKSUM; + goto finished; + } + dctx->state = ILEN1; + break; + case ILEN1: + if (dctx->nbits < 16) + goto finished; + cksum = dctx->bits & 0xFFFF; + EATBITS(16); + if (cksum != (dctx->bytesout & 0xFFFF)) { + error = DEFLATE_ERR_INLEN; + goto finished; + } + dctx->state = ILEN2; + break; + case ILEN2: + if (dctx->nbits < 16) + goto finished; + cksum = dctx->bits & 0xFFFF; + EATBITS(16); + if (cksum != ((dctx->bytesout >> 16) & 0xFFFF)) { + error = DEFLATE_ERR_INLEN; + goto finished; + } + dctx->state = FINALSPIN; + break; + case FINALSPIN: + /* Just ignore any trailing garbage on the data stream. */ + /* (We could alternatively throw an error here, if we wanted + * to detect and complain about trailing garbage.) */ + EATBITS(dctx->nbits); + break; + } + } + + finished: + *outblock = dctx->outblk; + *outlen = dctx->outlen; + return error; +} + +#define A(code,str) str +const char *const deflate_error_msg[DEFLATE_NUM_ERRORS] = { + DEFLATE_ERRORLIST(A) +}; +#undef A + +#define A(code,str) #code +const char *const deflate_error_sym[DEFLATE_NUM_ERRORS] = { + DEFLATE_ERRORLIST(A) +}; +#undef A + +#ifdef STANDALONE + +int main(int argc, char **argv) +{ + unsigned char buf[65536]; + void *outbuf; + int ret, err, outlen; + deflate_decompress_ctx *dhandle; + deflate_compress_ctx *chandle; + int type = DEFLATE_TYPE_ZLIB, opts = TRUE; + int compress = FALSE, decompress = FALSE; + int got_arg = FALSE; + char *filename = NULL; + FILE *fp; + + while (--argc) { + char *p = *++argv; + + got_arg = TRUE; + + if (p[0] == '-' && opts) { + if (!strcmp(p, "-b")) + type = DEFLATE_TYPE_BARE; + else if (!strcmp(p, "-g")) + type = DEFLATE_TYPE_GZIP; + else if (!strcmp(p, "-c")) + compress = TRUE; + else if (!strcmp(p, "-d")) + decompress = TRUE; + else if (!strcmp(p, "-a")) + analyse_level++, decompress = TRUE; + else if (!strcmp(p, "--")) + opts = FALSE; /* next thing is filename */ + else { + fprintf(stderr, "unknown command line option '%s'\n", p); + return 1; + } + } else if (!filename) { + filename = p; + } else { + fprintf(stderr, "can only handle one filename\n"); + return 1; + } + } + + if (!compress && !decompress) { + fprintf(stderr, "usage: deflate [ -c | -d | -a ] [ -b | -g ]" + " [filename]\n"); + return (got_arg ? 1 : 0); + } + + if (compress && decompress) { + fprintf(stderr, "please do not specify both compression and" + " decompression\n"); + return (got_arg ? 1 : 0); + } + + if (compress) { + chandle = deflate_compress_new(type); + dhandle = NULL; + } else { + dhandle = deflate_decompress_new(type); + chandle = NULL; + } + + if (filename) + fp = fopen(filename, "rb"); + else + fp = stdin; + + if (!fp) { + assert(filename); + fprintf(stderr, "unable to open '%s'\n", filename); + return 1; + } + + do { + ret = fread(buf, 1, sizeof(buf), fp); + outbuf = NULL; + if (dhandle) { + if (ret > 0) + err = deflate_decompress_data(dhandle, buf, ret, + (void **)&outbuf, &outlen); + else + err = deflate_decompress_data(dhandle, NULL, 0, + (void **)&outbuf, &outlen); + } else { + if (ret > 0) + deflate_compress_data(chandle, buf, ret, DEFLATE_NO_FLUSH, + (void **)&outbuf, &outlen); + else + deflate_compress_data(chandle, buf, ret, DEFLATE_END_OF_DATA, + (void **)&outbuf, &outlen); + err = 0; + } + if (outbuf) { + if (!analyse_level && outlen) + fwrite(outbuf, 1, outlen, stdout); + sfree(outbuf); + } + if (err > 0) { + fprintf(stderr, "decoding error: %s\n", deflate_error_msg[err]); + return 1; + } + } while (ret > 0); + + if (dhandle) + deflate_decompress_free(dhandle); + if (chandle) + deflate_compress_free(chandle); + + if (filename) + fclose(fp); + + return 0; +} + +#endif + +#ifdef TESTMODE + +int main(int argc, char **argv) +{ + char *filename = NULL; + FILE *fp; + deflate_compress_ctx *chandle; + deflate_decompress_ctx *dhandle; + unsigned char buf[65536], *outbuf, *outbuf2; + int ret, err, outlen, outlen2; + int dlen = 0, clen = 0; + int opts = TRUE; + + while (--argc) { + char *p = *++argv; + + if (p[0] == '-' && opts) { + if (!strcmp(p, "--")) + opts = FALSE; /* next thing is filename */ + else { + fprintf(stderr, "unknown command line option '%s'\n", p); + return 1; + } + } else if (!filename) { + filename = p; + } else { + fprintf(stderr, "can only handle one filename\n"); + return 1; + } + } + + if (filename) + fp = fopen(filename, "rb"); + else + fp = stdin; + + if (!fp) { + assert(filename); + fprintf(stderr, "unable to open '%s'\n", filename); + return 1; + } + + chandle = deflate_compress_new(DEFLATE_TYPE_ZLIB); + dhandle = deflate_decompress_new(DEFLATE_TYPE_ZLIB); + + do { + ret = fread(buf, 1, sizeof(buf), fp); + if (ret <= 0) { + deflate_compress_data(chandle, NULL, 0, DEFLATE_END_OF_DATA, + (void **)&outbuf, &outlen); + } else { + dlen += ret; + deflate_compress_data(chandle, buf, ret, DEFLATE_NO_FLUSH, + (void **)&outbuf, &outlen); + } + if (outbuf) { + clen += outlen; + err = deflate_decompress_data(dhandle, outbuf, outlen, + (void **)&outbuf2, &outlen2); + sfree(outbuf); + if (outbuf2) { + if (outlen2) + fwrite(outbuf2, 1, outlen2, stdout); + sfree(outbuf2); + } + if (!err && ret <= 0) { + /* + * signal EOF + */ + err = deflate_decompress_data(dhandle, NULL, 0, + (void **)&outbuf2, &outlen2); + assert(outbuf2 == NULL); + } + if (err) { + fprintf(stderr, "decoding error: %s\n", + deflate_error_msg[err]); + return 1; + } + } + } while (ret > 0); + + fprintf(stderr, "%d plaintext -> %d compressed\n", dlen, clen); + + return 0; +} + +#endif |