smaz.c

/*
Copyright (c) 2006-2009, Salvatore Sanfilippo
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
    * Neither the name of Smaz nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <string.h>

/* Our compression codebook, used for compression */
static const char *Smaz_cb[241] = {
"\002s,\266", "\003had\232\002leW", "\003on \216", "", "\001yS",
"\002ma\255\002li\227", "\003or \260", "", "\002ll\230\003s t\277",
"\004fromg\002mel", "", "\003its\332", "\001z\333", "\003ingF", "\001>\336",
"\001 \000\003   (\002nc\344", "\002nd=\003 on\312",
"\002ne\213\003hat\276\003re q", "", "\002ngT\003herz\004have\306\003s o\225",
"", "\003ionk\003s a\254\002ly\352", "\003hisL\003 inN\003 be\252", "",
"\003 fo\325\003 of \003 ha\311", "", "\002of\005",
"\003 co\241\002no\267\003 ma\370", "", "", "\003 cl\356\003enta\003 an7",
"\002ns\300\001\"e", "\003n t\217\002ntP\003s, \205",
"\002pe\320\003 we\351\002om\223", "\002on\037", "", "\002y G", "\003 wa\271",
"\003 re\321\002or*", "", "\002=\"\251\002ot\337", "\003forD\002ou[",
"\003 toR", "\003 th\r", "\003 it\366",
"\003but\261\002ra\202\003 wi\363\002</\361", "\003 wh\237", "\002  4",
"\003nd ?", "\002re!", "", "\003ng c", "",
"\003ly \307\003ass\323\001a\004\002rir", "", "", "", "\002se_", "\003of \"",
"\003div\364\002ros\003ere\240", "", "\002ta\310\001bZ\002si\324", "",
"\003and\a\002rs\335", "\002rt\362", "\002teE", "\003ati\316", "\002so\263",
"\002th\021", "\002tiJ\001c\034\003allp", "\003ate\345", "\002ss\246",
"\002stM", "", "\002><\346", "\002to\024", "\003arew", "\001d\030",
"\002tr\303", "", "\001\n1\003 a \222", "\003f tv\002veo", "\002un\340", "",
"\003e o\242", "\002a \243\002wa\326\001e\002", "\002ur\226\003e a\274",
"\002us\244\003\n\r\n\247", "\002ut\304\003e c\373", "\002we\221", "", "",
"\002wh\302", "\001f,", "", "", "", "\003d t\206", "", "", "\003th \343",
"\001g;", "", "", "\001\r9\003e s\265", "\003e t\234", "", "\003to Y",
"\003e\r\n\236", "\002d \036\001h\022", "", "\001,Q", "\002 a\031", "\002 b^",
"\002\r\n\025\002 cI", "\002 d\245", "\002 e\253", "\002 fh\001i\b\002e \v",
"", "\002 hU\001-\314", "\002 i8", "", "", "\002 l\315", "\002 m{",
"\002f :\002 n\354", "\002 o\035", "\002 p}\001.n\003\r\n\r\250", "",
"\002 r\275", "\002 s>", "\002 t\016", "", "\002g \235\005which+\003whi\367",
"\002 w5", "\001/\305", "\003as \214", "\003at \207", "", "\003who\331", "",
"\001l\026\002h \212", "", "\002, $", "", "\004withV", "", "", "", "\001m-", "",
"", "\002ac\357", "\002ad\350", "\003TheH", "", "", "\004this\233\001n\t",
"", "\002. y", "", "\002alX\003e, \365", "\003tio\215\002be\\",
"\002an\032\003ver\347", "", "\004that0\003tha\313\001o\006", "\003was2",
"\002arO", "\002as.", "\002at'\003the\001\004they\200\005there\322\005theird",
"\002ce\210", "\004were]", "", "\002ch\231\002l \264\001p<", "", "",
"\003one\256", "", "\003he \023\002dej", "\003ter\270", "\002cou", "",
"\002by\177\002di\201\002eax", "", "\002ec\327", "\002edB", "\002ee\353", "",
"", "\001r\f\002n )", "", "", "", "\002el\262", "", "\003in i\002en3", "",
"\002o `\001s\n", "", "\002er\033", "\003is t\002es6", "", "\002ge\371",
"\004.com\375", "\002fo\334\003our\330", "\003ch \301\001t\003", "\002hab", "",
"\003men\374", "", "\002he\020", "", "", "\001u&", "\002hif", "",
"\003not\204\002ic\203", "\003ed @\002id\355", "", "", "\002ho\273",
"\002r K\001vm", "", "", "", "\003t t\257\002il\360", "\002im\342",
"\003en \317\002in\017", "\002io\220", "\002s \027\001wA", "", "\003er |",
"\003es ~\002is%", "\002it/", "", "\002iv\272", "",
"\002t #\ahttp://C\001x\372", "\002la\211", "\001<\341", "\003, a\224"
};

/* Reverse compression codebook, used for decompression */
static char *Smaz_rcb[254] = {
" ", "the", "e", "t", "a", "of", "o", "and", "i", "n", "s", "e ", "r", " th",
" t", "in", "he", "th", "h", "he ", "to", "\r\n", "l", "s ", "d", " a", "an",
"er", "c", " o", "d ", "on", " of", "re", "of ", "t ", ", ", "is", "u", "at",
"   ", "n ", "or", "which", "f", "m", "as", "it", "that", "\n", "was", "en",
"  ", " w", "es", " an", " i", "\r", "f ", "g", "p", "nd", " s", "nd ", "ed ",
"w", "ed", "http://", "for", "te", "ing", "y ", "The", " c", "ti", "r ", "his",
"st", " in", "ar", "nt", ",", " to", "y", "ng", " h", "with", "le", "al", "to ",
"b", "ou", "be", "were", " b", "se", "o ", "ent", "ha", "ng ", "their", "\"",
"hi", "from", " f", "in ", "de", "ion", "me", "v", ".", "ve", "all", "re ",
"ri", "ro", "is ", "co", "f t", "are", "ea", ". ", "her", " m", "er ", " p",
"es ", "by", "they", "di", "ra", "ic", "not", "s, ", "d t", "at ", "ce", "la",
"h ", "ne", "as ", "tio", "on ", "n t", "io", "we", " a ", "om", ", a", "s o",
"ur", "li", "ll", "ch", "had", "this", "e t", "g ", "e\r\n", " wh", "ere",
" co", "e o", "a ", "us", " d", "ss", "\n\r\n", "\r\n\r", "=\"", " be", " e",
"s a", "ma", "one", "t t", "or ", "but", "el", "so", "l ", "e s", "s,", "no",
"ter", " wa", "iv", "ho", "e a", " r", "hat", "s t", "ns", "ch ", "wh", "tr",
"ut", "/", "have", "ly ", "ta", " ha", " on", "tha", "-", " l", "ati", "en ",
"pe", " re", "there", "ass", "si", " fo", "wa", "ec", "our", "who", "its", "z",
"fo", "rs", ">", "ot", "un", "<", "im", "th ", "nc", "ate", "><", "ver", "ad",
" we", "ly", "ee", " n", "id", " cl", "ac", "il", "</", "rt", " wi", "div",
"e, ", " it", "whi", " ma", "ge", "x", "e c", "men", ".com"
};

int smaz_compress(const char *in, int inlen, char *out, int outlen) {
    unsigned int h1,h2,h3=0;
    int verblen = 0, _outlen = outlen;
    char verb[256], *_out = out;

    while(inlen) {
        int j = 7, needed;
        char *flush = NULL;
        char *slot;

        h1 = h2 = in[0]<<3;
        if (inlen > 1) h2 += in[1];
        if (inlen > 2) h3 = h2^in[2];
        if (j > inlen) j = inlen;

        /* Try to lookup substrings into the hash table, starting from the
         * longer to the shorter substrings */
        for (; j > 0; j--) {
            switch(j) {
            case 1: slot = Smaz_cb[h1%241]; break;
            case 2: slot = Smaz_cb[h2%241]; break;
            default: slot = Smaz_cb[h3%241]; break;
            }
            while(slot[0]) {
                if (slot[0] == j && memcmp(slot+1,in,j) == 0) {
                    /* Match found in the hash table,
                     * prepare a verbatim bytes flush if needed */
                    if (verblen) {
                        needed = (verblen == 1) ? 2 : 2+verblen;
                        flush = out;
                        out += needed;
                        outlen -= needed;
                    }
                    /* Emit the byte */
                    if (outlen <= 0) return _outlen+1;
                    out[0] = slot[slot[0]+1];
                    out++;
                    outlen--;
                    inlen -= j;
                    in += j;
                    goto out;
                } else {
                    slot += slot[0]+2;
                }
            }
        }
        /* Match not found - add the byte to the verbatim buffer */
        verb[verblen] = in[0];
        verblen++;
        inlen--;
        in++;
out:
        /* Prepare a flush if we reached the flush length limit, and there
         * is not already a pending flush operation. */
        if (!flush && (verblen == 256 || (verblen > 0 && inlen == 0))) {
            needed = (verblen == 1) ? 2 : 2+verblen;
            flush = out;
            out += needed;
            outlen -= needed;
            if (outlen < 0) return _outlen+1;
        }
        /* Perform a verbatim flush if needed */
        if (flush) {
            if (verblen == 1) {
                flush[0] = (signed char)254;
                flush[1] = verb[0];
            } else {
                flush[0] = (signed char)255;
                flush[1] = (signed char)(verblen-1);
                memcpy(flush+2,verb,verblen);
            }
            flush = NULL;
            verblen = 0;
        }
    }
    return out-_out;
}

int smaz_decompress(const char *in, int inlen, char *out, int outlen) {
    unsigned char *c = (unsigned char*) in;
    char *_out = out;
    int _outlen = outlen;

    while(inlen) {
        if (*c == 254) {
            /* Verbatim byte */
            if (outlen < 1) return _outlen+1;
            *out = *(c+1);
            out++;
            outlen--;
            c += 2;
            inlen -= 2;
        } else if (*c == 255) {
            /* Verbatim string */
            int len = (*(c+1))+1;
            if (outlen < len) return _outlen+1;
            memcpy(out,c+2,len);
            out += len;
            outlen -= len;
            c += 2+len;
            inlen -= 2+len;
        } else {
            /* Codebook entry */
            const char *s = Smaz_rcb[*c];
            int len = strlen(s);

            if (outlen < len) return _outlen+1;
            memcpy(out,s,len);
            out += len;
            outlen -= len;
            c++;
            inlen--;
        }
    }
    return out-_out;
}