aom/test/acm_random.h

74 строки
1.8 KiB
C++

/*
* Copyright (c) 2012 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef TEST_ACM_RANDOM_H_
#define TEST_ACM_RANDOM_H_
#include "third_party/googletest/src/include/gtest/gtest.h"
#include "vpx/vpx_integer.h"
namespace libvpx_test {
class ACMRandom {
public:
ACMRandom() : random_(DeterministicSeed()) {}
explicit ACMRandom(int seed) : random_(seed) {}
void Reset(int seed) {
random_.Reseed(seed);
}
uint16_t Rand16(void) {
const uint32_t value =
random_.Generate(testing::internal::Random::kMaxRange);
return (value >> 15) & 0xffff;
}
int16_t Rand9Signed(void) {
// Use 9 bits: values between 255 (0x0FF) and -256 (0x100).
const uint32_t value = random_.Generate(512);
return static_cast<int16_t>(value) - 256;
}
uint8_t Rand8(void) {
const uint32_t value =
random_.Generate(testing::internal::Random::kMaxRange);
// There's a bit more entropy in the upper bits of this implementation.
return (value >> 23) & 0xff;
}
uint8_t Rand8Extremes(void) {
// Returns a random value near 0 or near 255, to better exercise
// saturation behavior.
const uint8_t r = Rand8();
return r < 128 ? r << 4 : r >> 4;
}
int PseudoUniform(int range) {
return random_.Generate(range);
}
int operator()(int n) {
return PseudoUniform(n);
}
static int DeterministicSeed(void) {
return 0xbaba;
}
private:
testing::internal::Random random_;
};
} // namespace libvpx_test
#endif // TEST_ACM_RANDOM_H_