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coova-chilli

    1: #include "system.h"
    2: #undef get16bits
    3: #if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) \
    4:   || defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
    5: #define get16bits(d) (*((const uint16_t *) (d)))
    6: #endif
    7: 
    8: #if !defined (get16bits)
    9: #define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
   10:                        +(uint32_t)(((const uint8_t *)(d))[0]) )
   11: #endif
   12: 
   13: uint32_t SuperFastHash (const char * data, int len, uint32_t hash) {
   14: uint32_t tmp;
   15: int rem;
   16: 
   17:     if (len <= 0 || data == NULL) return 0;
   18: 
   19:     rem = len & 3;
   20:     len >>= 2;
   21: 
   22:     /* Main loop */
   23:     for (;len > 0; len--) {
   24:         hash  += get16bits (data);
   25:         tmp    = (get16bits (data+2) << 11) ^ hash;
   26:         hash   = (hash << 16) ^ tmp;
   27:         data  += 2*sizeof (uint16_t);
   28:         hash  += hash >> 11;
   29:     }
   30: 
   31:     /* Handle end cases */
   32:     switch (rem) {
   33:         case 3: hash += get16bits (data);
   34:                 hash ^= hash << 16;
   35:                 hash ^= data[sizeof (uint16_t)] << 18;
   36:                 hash += hash >> 11;
   37:                 break;
   38:         case 2: hash += get16bits (data);
   39:                 hash ^= hash << 11;
   40:                 hash += hash >> 17;
   41:                 break;
   42:         case 1: hash += *data;
   43:                 hash ^= hash << 10;
   44:                 hash += hash >> 1;
   45:     }
   46: 
   47:     /* Force "avalanching" of final 127 bits */
   48:     hash ^= hash << 3;
   49:     hash += hash >> 5;
   50:     hash ^= hash << 4;
   51:     hash += hash >> 17;
   52:     hash ^= hash << 25;
   53:     hash += hash >> 6;
   54: 
   55:     return hash;
   56: }