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:
ACMRandom()22   ACMRandom() : random_(DeterministicSeed()) {}
23 
ACMRandom(int seed)24   explicit ACMRandom(int seed) : random_(seed) {}
25 
Reset(int seed)26   void Reset(int seed) {
27     random_.Reseed(seed);
28   }
Rand16(void)29   uint16_t Rand16(void) {
30     const uint32_t value =
31         random_.Generate(testing::internal::Random::kMaxRange);
32     return (value >> 15) & 0xffff;
33   }
34 
Rand8(void)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 
Rand8Extremes(void)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 
PseudoUniform(int range)49   int PseudoUniform(int range) {
50     return random_.Generate(range);
51   }
52 
operator()53   int operator()(int n) {
54     return PseudoUniform(n);
55   }
56 
DeterministicSeed(void)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_
68