libs/core/GP_TestingRandom.c

   1 /*****************************************************************************
   2  * This file is part of gfxprim library.                                     *
   3  *                                                                           *
   4  * Gfxprim is free software; you can redistribute it and/or                  *
   5  * modify it under the terms of the GNU Lesser General Public                *
   6  * License as published by the Free Software Foundation; either              *
   7  * version 2.1 of the License, or (at your option) any later version.        *
   8  *                                                                           *
   9  * Gfxprim is distributed in the hope that it will be useful,                *
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU         *
  12  * Lesser General Public License for more details.                           *
  13  *                                                                           *
  14  * You should have received a copy of the GNU Lesser General Public          *
  15  * License along with gfxprim; if not, write to the Free Software            *
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,                        *
  17  * Boston, MA  02110-1301  USA                                               *
  18  *                                                                           *
  19  * Copyright (C) 2011      Tomas Gavenciak <gavento@ucw.cz>                  *
  20  *                                                                           *
  21  *****************************************************************************/
  22
  23 #include <stdlib.h>
  24
  25 #include "GP_Common.h"
  26 #include "GP_TestingRandom.h"
  27
  28 /*
  29  * State array for testing random generator
  30  *
  31  * The idea is to have a seperate random generator for generating
  32  * random inputs for tests in case tested algorithms also use
  33  * the random generator. Change in the tested algorithm must not
  34  * change the input data generated for this or other part of the test.
  35  *
  36  * Take care when changing the values - unrelated test might start
  37  * exhibiting a bug, some tests may rely on the exact result.
  38  */
  39 #define GP_RandomStateSize 256
  40 static char GP_RandomTestingState[GP_RandomStateSize];
  41 static struct random_data GP_RandomTestingData;
  42
  43 long int GP_TestingRandom(void)
  44 {
  45         int32_t r;
  46         GP_ASSERT(random_r(&GP_RandomTestingData, &r) == 0);
  47         return r;
  48 }
  49
  50 void GP_InitTestingRandom(const char *text, uint64_t seed)
  51 {
  52         const char *p = text;
  53         for (; (p) && (*p); p++)
  54                 seed = ((seed * 327) + *p) % 0x7B391D50A10A3LL; // TODO replace with large primes
  55         GP_ASSERT(initstate_r(seed, GP_RandomTestingState, GP_RandomStateSize,
  56                               &GP_RandomTestingData) == 0);
  57 }
  58