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 "third_party/googletest/src/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 Rand13Signed()48 int16_t Rand13Signed() { 49 // Use 13 bits: values between 4095 and -4096. 50 const uint32_t value = random_.Generate(8192); 51 return static_cast<int16_t>(value) - 4096; 52 } 53 Rand9Signed()54 int16_t Rand9Signed() { 55 // Use 9 bits: values between 255 (0x0FF) and -256 (0x100). 56 const uint32_t value = random_.Generate(512); 57 return static_cast<int16_t>(value) - 256; 58 } 59 Rand8()60 uint8_t Rand8() { 61 const uint32_t value = 62 random_.Generate(testing::internal::Random::kMaxRange); 63 // There's a bit more entropy in the upper bits of this implementation. 64 return (value >> 23) & 0xff; 65 } 66 Rand8Extremes()67 uint8_t Rand8Extremes() { 68 // Returns a random value near 0 or near 255, to better exercise 69 // saturation behavior. 70 const uint8_t r = Rand8(); 71 return static_cast<uint8_t>((r < 128) ? r << 4 : r >> 4); 72 } 73 RandRange(const uint32_t range)74 uint32_t RandRange(const uint32_t range) { 75 // testing::internal::Random::Generate provides values in the range 76 // testing::internal::Random::kMaxRange. 77 assert(range <= testing::internal::Random::kMaxRange); 78 return random_.Generate(range); 79 } 80 PseudoUniform(int range)81 int PseudoUniform(int range) { return random_.Generate(range); } 82 operator()83 int operator()(int n) { return PseudoUniform(n); } 84 DeterministicSeed()85 static int DeterministicSeed() { return 0xbaba; } 86 87 private: 88 testing::internal::Random random_; 89 }; 90 91 } // namespace libvpx_test 92 93 #endif // VPX_TEST_ACM_RANDOM_H_ 94