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C语言自定义的一个字符串压缩库

OC/C/C++ 水墨上仙 1682次浏览 已收录 手机上查看

C语言自定义的一个字符串压缩库

该代码转自:https://github.com/antirez/smaz/

smaz.h文件代码



#ifndef _SMAZ_H
#define _SMAZ_H

int smaz_compress(char *in, int inlen, char *out, int outlen);
int smaz_decompress(char *in, int inlen, char *out, int outlen);

#endif


smaz.c文件代码



#include <string.h>

/* Our compression codebook, used for compression */
static 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(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(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 */
            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;
}

测试代码


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "smaz.h"

int main(void) {
    char in[512];
    char out[4096];
    char d[4096];
    int comprlen, decomprlen;
    int j, ranlen;
    int times = 1000000;
    char *strings[] = {
        "This is a small string",
        "foobar",
        "the end",
        "not-a-g00d-Exampl333",
        "Smaz is a simple compression library",
        "Nothing is more difficult, and therefore more precious, than to be able to decide",
        "this is an example of what works very well with smaz",
        "1000 numbers 2000 will 10 20 30 compress very little",
        "and now a few italian sentences:",
        "Nel mezzo del cammin di nostra vita, mi ritrovai in una selva oscura",
        "Mi illumino di immenso",
        "L'autore di questa libreria vive in Sicilia",
        "try it against urls",
        "http://google.com",
        "http://programming.reddit.com",
        "http://github.com/antirez/smaz/tree/master",
        "/media/hdb1/music/Alben/The Bla",
        NULL
    };

    j=0;
    while(strings[j]) {
        int comprlevel;

        comprlen = smaz_compress(strings[j],strlen(strings[j]),out,sizeof(out));
        comprlevel = 100-((100*comprlen)/strlen(strings[j]));
        decomprlen = smaz_decompress(out,comprlen,d,sizeof(d));
        if (strlen(strings[j]) != (unsigned)decomprlen ||
            memcmp(strings[j],d,decomprlen))
        {
            printf("BUG: error compressing '%s'\n", strings[j]);
            exit(1);
        }
        if (comprlevel < 0) {
            printf("'%s' enlarged by %d%%\n",strings[j],-comprlevel);
        } else {
            printf("'%s' compressed by %d%%\n",strings[j],comprlevel);
        }
        j++;
    }
    printf("Encrypting and decrypting %d test strings...\n", times);
    while(times--) {
        char charset[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvxyz/. ";
        ranlen = random() % 512;

        for (j = 0; j < ranlen; j++) {
            if (times & 1)
                in[j] = charset[random() % (sizeof(charset)-1)];
            else
                in[j] = (char)(random() & 0xff);
        }
        comprlen = smaz_compress(in,ranlen,out,sizeof(out));
        decomprlen = smaz_decompress(out,comprlen,d,sizeof(out));

        if (ranlen != decomprlen || memcmp(in,d,ranlen)) {
            printf("Bug! TEST NOT PASSED\n");
            exit(1);
        }
        /* printf("%d -> %d\n", comprlen, decomprlen); */
    }
    printf("TEST PASSED :)\n");
    return 0;
}


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