Bunch of hash functions

gistfile1.cpp

unsigned int djb2(const char *text, int len)
{
   unsigned int hash = 5381;
   int c;

   while(c = *text++)
      hash = ((hash << 5) + hash) + c;

   return hash;
}

unsigned int sdbm(const char *text, int len)
{
   unsigned int hash = 0;
   int c;

   while(c = *text++)
      hash = c + (hash << 6) + (hash << 16) - hash;

   return hash;
}

unsigned int fnv1a(const char *text, int len)
{
   const int fnvOffsetBasis = 2166136261;
   const int fnvPrime = 16777619;

   unsigned int hash = fnvOffsetBasis;
   for(int i = 0; i < len; ++i, ++text)
   {
      hash = hash ^ (unsigned int)(*text);
      hash *= fnvPrime;
   }

   return hash;
}

unsigned long long fnv1a64(const char *text, int len)
{
   const long long fnvOffsetBasis = 14695981039346656037ULL;
   const long long fnvPrime = 1099511628211ULL;

   unsigned long long hash = fnvOffsetBasis;
   for(int i = 0; i < len; ++i, ++text)
   {
      hash = hash ^ (unsigned long long)(*text);
      hash *= fnvPrime;
   }

   return hash;
}