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             : }