/*
 * .============.
 * // M A K E / \
 * // C++ DEV / \
 * // E A S Y / \/ \
 * ++ ----------. \/\ .
 * \\ \ \ /\ /
 * \\ \ \ /
 * \\ \ \ /
 * -============'
 *
 * Copyright (c) 2018 Hevake and contributors, all rights reserved.
 *
 * This file is part of cpp-tbox (https://github.com/cpp-main/cpp-tbox)
 * Use of this source code is governed by MIT license that can be found
 * in the LICENSE file in the root of the source tree. All contributing
 * project authors may be found in the CONTRIBUTORS.md file in the root
 * of the source tree.
 */
#include "checksum.h"

namespace tbox {
namespace util {

uint8_t CalcCheckSum8(const void *data_ptr, size_t data_size)
{
 const uint8_t *byte_ptr = (const uint8_t *)data_ptr;
 uint16_t acc = 0;

 for (size_t i = 0; i < data_size; ++i) {
 acc += byte_ptr[i];
 while ((acc & 0xff00) != 0)
 acc = (acc & 0xff) + (acc >> 8);
 }

 return ~((uint8_t)acc);
}

uint16_t CalcCheckSum16(const void *data_ptr, size_t data_size)
{
 uint32_t acc = 0;

 if (data_size > 0) {
 uint8_t *bytes = (uint8_t*)data_ptr;

 while (data_size > 1) {
 acc += (bytes[0] << 8 | bytes[1]);
 while ((acc & 0xffff0000UL) != 0)
 acc = (acc >> 16) + (acc & 0x0000ffffUL);

 bytes += 2;
 data_size -= 2;
 }

 if (data_size > 0) {
 acc += (bytes[0] << 8);
 while ((acc & 0xffff0000UL) != 0)
 acc = (acc >> 16) + (acc & 0x0000ffffUL);
 }
 }

 uint16_t ret = (uint16_t)acc;
 return ~ret;
}

}
}