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/*
*
* Copyright (c) 2020 Project CHIP Authors
* Copyright (c) 2013-2017 Nest Labs, Inc.
*
* Licensed 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.
*/
/**
* @file
* This file implements an object for the core Verhoeff
* check-digit algorithm operations.
*
*/
#include "Verhoeff.h"
int Verhoeff::DihedralMultiply(int x, int y, int n)
{
int n2 = n * 2;
x = x % n2;
y = y % n2;
if (x < n)
{
if (y < n)
return (x + y) % n;
return ((x + (y - n)) % n) + n;
}
if (y < n)
return ((n + (x - n) - y) % n) + n;
return (n + (x - n) - (y - n)) % n;
}
int Verhoeff::DihedralInvert(int val, int n)
{
if (val > 0 && val < n)
return n - val;
return val;
}
int Verhoeff::Permute(int val, const uint8_t * permTable, int permTableLen, uint64_t iterCount)
{
val = val % permTableLen;
if (iterCount == 0)
return val;
return Permute(permTable[val], permTable, permTableLen, iterCount - 1);
}