used like:
    node = db->ht[db->hash(key, db->maxlen)%HASH_SIZE];
    while (node) {
        c = db->cmp(key, node->key, db->maxlen);
        if (c == 0) {
            if (!(node->deleted)) {
                db->cache = node;
                found = true;
            }
            break;
        }
        if (c < 0)
            node = node->left;
        else
            node = node->right;
    }
---
 
/**
 * Default hasher for DB_INT databases.
 * Returns the value of the key as an unsigned int.
 * <code>maxlen</code> is ignored.
 * @param key Key to be hashed
 * @param maxlen Maximum length of the key to hash
 * @return hash of the key
 * @see DBType#DB_INT
 * @see #DBHasher
 * @see #db_default_hash(DBType)
 */
static unsigned int db_int_hash(DBKey key, unsigned short maxlen)
{
    (void)maxlen;//not used
    DB_COUNTSTAT(db_int_hash);
    return (unsigned int)key.i;
}
 
/**
 * Default hasher for DB_UINT databases.
 * Just returns the value of the key.
 * <code>maxlen</code> is ignored.
 * @param key Key to be hashed
 * @param maxlen Maximum length of the key to hash
 * @return hash of the key
 * @see DBType#DB_UINT
 * @see #DBHasher
 * @see #db_default_hash(DBType)
 */
static unsigned int db_uint_hash(DBKey key, unsigned short maxlen)
{
    (void)maxlen;//not used
    DB_COUNTSTAT(db_uint_hash);
    return key.ui;
}
 
/**
 * Default hasher for DB_STRING databases.
 * @param key Key to be hashed
 * @param maxlen Maximum length of the key to hash
 * @return hash of the key
 * @see DBType#DB_STRING
 * @see #DBHasher
 * @see #db_default_hash(DBType)
 */
static unsigned int db_string_hash(DBKey key, unsigned short maxlen)
{
    const char *k = key.str;
    unsigned int hash = 0;
    unsigned short i;
 
    DB_COUNTSTAT(db_string_hash);
 
    for (i = 0; *k; ++i) {
        hash = (hash*33 + ((unsigned char)*k))^(hash>>24);
        k++;
        if (i == maxlen)
            break;
    }
 
    return hash;
}
 
/**
 * Default hasher for DB_ISTRING databases.
 * @param key Key to be hashed
 * @param maxlen Maximum length of the key to hash
 * @return hash of the key
 * @see DBType#DB_ISTRING
 * @see #db_default_hash(DBType)
 */
static unsigned int db_istring_hash(DBKey key, unsigned short maxlen)
{
    const char *k = key.str;
    unsigned int hash = 0;
    unsigned short i;
 
    DB_COUNTSTAT(db_istring_hash);
 
    for (i = 0; *k; i++) {
        hash = (hash*33 + ((unsigned char)TOLOWER(*k)))^(hash>>24);
        k++;
        if (i == maxlen)
            break;
    }
 
    return hash;
}
 
/**
 * Default hasher for DB_INT64 databases.
 * Returns the value of the key as an unsigned int.
 * <code>maxlen</code> is ignored.
 * @param key Key to be hashed
 * @param maxlen Maximum length of the key to hash
 * @return hash of the key
 * @see DBType#DB_INT64
 * @see #DBHasher
 * @see #db_default_hash(DBType)
 */
static unsigned int db_int64_hash(DBKey key, unsigned short maxlen)
{
    (void)maxlen;//not used
    DB_COUNTSTAT(db_int64_hash);
    return (unsigned int)key.i64;
}
 
/**
 * Default hasher for DB_UINT64 databases.
 * Just returns the value of the key.
 * <code>maxlen</code> is ignored.
 * @param key Key to be hashed
 * @param maxlen Maximum length of the key to hash
 * @return hash of the key
 * @see DBType#DB_UINT64
 * @see #DBHasher
 * @see #db_default_hash(DBType)
 */
static unsigned int db_uint64_hash(DBKey key, unsigned short maxlen)
{
    (void)maxlen;//not used
    DB_COUNTSTAT(db_uint64_hash);
    return (unsigned int)key.ui64;
}