/*

 * Licensed to Systerel under one or more contributor license

 * agreements. See the NOTICE file distributed with this work

 * for additional information regarding copyright ownership.

 * Systerel 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.

 */

#include "sopc_hash.h"

uint64_t SOPC_DJBHash(const uint8_t* data, size_t len)

{

    return SOPC_DJBHash_Step(5381, data, len);

}

uint64_t SOPC_DJBHash_Step(uint64_t current, const uint8_t* data, size_t len)

{

    for (size_t i = 0; i < len; ++i)

    {

        current = (current << 5) + current + data[i];

    }

    return current;

}

/* Constants of the 64-bit FNV-1a hash, as specified by its authors: offset basis

 * 0xcbf29ce484222325 and prime 0x100000001b3. */

#define FNV1A_OFFSET_BASIS 14695981039346656037ULL

#define FNV1A_PRIME 1099511628211ULL

uint64_t SOPC_FNV1aHash(const uint8_t* data, size_t len)

{

    return SOPC_FNV1aHash_Step(FNV1A_OFFSET_BASIS, data, len);

}

uint64_t SOPC_FNV1aHash_Step(uint64_t current, const uint8_t* data, size_t len)

{

    for (size_t i = 0; i < len; ++i)

    {

        // FNV-1a: xor before multiply (FNV-1 does the opposite and diffuses less)

        current ^= data[i];

        current *= FNV1A_PRIME;

    }

    return current;

}