test/acm_random.h

   1 /*
   2  *  Copyright (c) 2012 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11 #ifndef TEST_ACM_RANDOM_H_
  12 #define TEST_ACM_RANDOM_H_
  13
  14 #include "third_party/googletest/src/include/gtest/gtest.h"
  15
  16 #include "vpx/vpx_integer.h"
  17
  18 namespace libvpx_test {
  19
  20 class ACMRandom {
  21  public:
  22   ACMRandom() : random_(DeterministicSeed()) {}
  23
  24   explicit ACMRandom(int seed) : random_(seed) {}
  25
  26   void Reset(int seed) {
  27     random_.Reseed(seed);
  28   }
  29   uint16_t Rand16(void) {
  30     const uint32_t value =
  31         random_.Generate(testing::internal::Random::kMaxRange);
  32     return (value >> 15) & 0xffff;
  33   }
  34
  35   uint8_t Rand8(void) {
  36     const uint32_t value =
  37         random_.Generate(testing::internal::Random::kMaxRange);
  38     // There's a bit more entropy in the upper bits of this implementation.
  39     return (value >> 23) & 0xff;
  40   }
  41
  42   uint8_t Rand8Extremes(void) {
  43     // Returns a random value near 0 or near 255, to better exercise
  44     // saturation behavior.
  45     const uint8_t r = Rand8();
  46     return r < 128 ? r << 4 : r >> 4;
  47   }
  48
  49   int PseudoUniform(int range) {
  50     return random_.Generate(range);
  51   }
  52
  53   int operator()(int n) {
  54     return PseudoUniform(n);
  55   }
  56
  57   static int DeterministicSeed(void) {
  58     return 0xbaba;
  59   }
  60
  61  private:
  62   testing::internal::Random random_;
  63 };
  64
  65 }  // namespace libvpx_test
  66
  67 #endif  // TEST_ACM_RANDOM_H_