/*!The Treasure Box Library
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 * Copyright (C) 2009 - 2017, TBOOX Open Source Group.
 *
 * @author      ruki
 * @file        rs.c
 * @ingroup     hash
 *
 */

/* //////////////////////////////////////////////////////////////////////////////////////
 * includes
 */
#include "rs.h"

/* //////////////////////////////////////////////////////////////////////////////////////
 * implementation
 */
tb_size_t tb_rs_make(tb_byte_t const* data, tb_size_t size, tb_size_t seed)
{
    // check
    tb_assert_and_check_return_val(data && size, 0);

    // init value
    tb_size_t value = seed;

    // generate it
    tb_size_t b = 378551;  
    tb_size_t a = 63689;  
    while (size--)
    {  
        value = value * a + (*data++);  
        a = a * b;  
    }  
    return value;
}
tb_size_t tb_rs_make_from_cstr(tb_char_t const* cstr, tb_size_t seed)
{
    // check
    tb_assert_and_check_return_val(cstr, 0);

    // make it
    return tb_rs_make((tb_byte_t const*)cstr, tb_strlen(cstr) + 1, seed);
}
