ccutil/hashfn.cpp

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#include          "mfcpch.h"     //precompiled headers
#include          "hashfn.h"

INT32 hash(               //hash function
           INT32 bits,    //bits in hash function
           void *key,     //key to hash
           INT32 keysize  //size of key
          ) {
  INT32 bitindex;                //current bit count
  UINT32 keybits;                //bit buffer
  UINT32 hcode;                  //current hash code
  UINT32 mask;                   //bit mask

  mask = (1 << bits) - 1;
  keysize *= 8;                  //in bits
  bitindex = 0;
  keybits = 0;
  hcode = 0;
  do {
    while (keysize > 0 && bitindex <= 24) {
      keybits |= *((UINT8 *) key) << bitindex;
      key = (UINT8 *) key + 1;
      bitindex += 8;
      keysize -= 8;
    }
    hcode ^= keybits & mask;     //key new key
    keybits >>= bits;
  }
  while (keysize > 0);
  return hcode;                  //initial hash
}

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