Line data    Source code

       1              : /*
       2              :  *
       3              :  *    Copyright (c) 2020 Project CHIP Authors
       4              :  *    Copyright (c) 2013-2017 Nest Labs, Inc.
       5              :  *
       6              :  *    Licensed under the Apache License, Version 2.0 (the "License");
       7              :  *    you may not use this file except in compliance with the License.
       8              :  *    You may obtain a copy of the License at
       9              :  *
      10              :  *        http://www.apache.org/licenses/LICENSE-2.0
      11              :  *
      12              :  *    Unless required by applicable law or agreed to in writing, software
      13              :  *    distributed under the License is distributed on an "AS IS" BASIS,
      14              :  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      15              :  *    See the License for the specific language governing permissions and
      16              :  *    limitations under the License.
      17              :  */
      18              : /**
      19              :  *    @file
      20              :  *      This file implements an object for the core Verhoeff
      21              :  *      check-digit algorithm operations.
      22              :  *
      23              :  */
      24              : 
      25              : #include "Verhoeff.h"
      26              : 
      27            0 : int Verhoeff::DihedralMultiply(int x, int y, int n)
      28              : {
      29            0 :     int n2 = n * 2;
      30              : 
      31            0 :     x = x % n2;
      32            0 :     y = y % n2;
      33              : 
      34            0 :     if (x < n)
      35              :     {
      36            0 :         if (y < n)
      37            0 :             return (x + y) % n;
      38              : 
      39            0 :         return ((x + (y - n)) % n) + n;
      40              :     }
      41              : 
      42            0 :     if (y < n)
      43            0 :         return ((n + (x - n) - y) % n) + n;
      44              : 
      45            0 :     return (n + (x - n) - (y - n)) % n;
      46              : }
      47              : 
      48           62 : int Verhoeff::DihedralInvert(int val, int n)
      49              : {
      50           62 :     if (val > 0 && val < n)
      51           23 :         return n - val;
      52           39 :     return val;
      53              : }
      54              : 
      55         9047 : int Verhoeff::Permute(int val, const uint8_t * permTable, int permTableLen, uint64_t iterCount)
      56              : {
      57         9047 :     val = val % permTableLen;
      58         9047 :     if (iterCount == 0)
      59          908 :         return val;
      60         8139 :     return Permute(permTable[val], permTable, permTableLen, iterCount - 1);
      61              : }