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 VPX_TEST_ACM_RANDOM_H_ 12 #define VPX_TEST_ACM_RANDOM_H_ 13 14 #include <assert.h> 15 16 #include <limits> 17 18 #include "gtest/gtest.h" 19 20 #include "vpx/vpx_integer.h" 21 22 namespace libvpx_test { 23 24 class ACMRandom { 25 public: ACMRandom()26 ACMRandom() : random_(DeterministicSeed()) {} 27 ACMRandom(int seed)28 explicit ACMRandom(int seed) : random_(seed) {} 29 Reset(int seed)30 void Reset(int seed) { random_.Reseed(seed); } Rand16()31 uint16_t Rand16() { 32 const uint32_t value = 33 random_.Generate(testing::internal::Random::kMaxRange); 34 return (value >> 15) & 0xffff; 35 } 36 Rand20Signed()37 int32_t Rand20Signed() { 38 // Use 20 bits: values between 524287 and -524288. 39 const uint32_t value = random_.Generate(1048576); 40 return static_cast<int32_t>(value) - 524288; 41 } 42 Rand16Signed()43 int16_t Rand16Signed() { 44 // Use 16 bits: values between 32767 and -32768. 45 return static_cast<int16_t>(random_.Generate(65536)); 46 } 47 Rand12()48 uint16_t Rand12() { 49 const uint32_t value = 50 random_.Generate(testing::internal::Random::kMaxRange); 51 // There's a bit more entropy in the upper bits of this implementation. 52 return (value >> 19) & 0xfff; 53 } 54 Rand8()55 uint8_t Rand8() { 56 const uint32_t value = 57 random_.Generate(testing::internal::Random::kMaxRange); 58 // There's a bit more entropy in the upper bits of this implementation. 59 return (value >> 23) & 0xff; 60 } 61 Rand8Extremes()62 uint8_t Rand8Extremes() { 63 // Returns a random value near 0 or near 255, to better exercise 64 // saturation behavior. 65 const uint8_t r = Rand8(); 66 return static_cast<uint8_t>((r < 128) ? r << 4 : r >> 4); 67 } 68 RandRange(const uint32_t range)69 uint32_t RandRange(const uint32_t range) { 70 // testing::internal::Random::Generate provides values in the range 71 // testing::internal::Random::kMaxRange. 72 assert(range <= testing::internal::Random::kMaxRange); 73 return random_.Generate(range); 74 } 75 PseudoUniform(int range)76 int PseudoUniform(int range) { return random_.Generate(range); } 77 operator()78 int operator()(int n) { return PseudoUniform(n); } 79 DeterministicSeed()80 static int DeterministicSeed() { return 0xbaba; } 81 82 private: 83 testing::internal::Random random_; 84 }; 85 86 } // namespace libvpx_test 87 88 #endif // VPX_TEST_ACM_RANDOM_H_ 89