acm_random.h 1.62 KB
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/*
 *  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.
 */

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#ifndef TEST_ACM_RANDOM_H_
#define TEST_ACM_RANDOM_H_
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#include "third_party/googletest/src/include/gtest/gtest.h"
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#include "vpx/vpx_integer.h"

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namespace libvpx_test {

class ACMRandom {
 public:
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  ACMRandom() : random_(DeterministicSeed()) {}
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  explicit ACMRandom(int seed) : random_(seed) {}
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  void Reset(int seed) {
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    random_.Reseed(seed);
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  }
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  uint16_t Rand16(void) {
    const uint32_t value =
        random_.Generate(testing::internal::Random::kMaxRange);
    return (value >> 16) & 0xffff;
  }
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  uint8_t Rand8(void) {
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    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 >> 24) & 0xff;
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  }

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  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;
  }

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  int PseudoUniform(int range) {
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    return random_.Generate(range);
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  }

  int operator()(int n) {
    return PseudoUniform(n);
  }

  static int DeterministicSeed(void) {
    return 0xbaba;
  }
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 private:
  testing::internal::Random random_;
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};

}  // namespace libvpx_test

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#endif  // TEST_ACM_RANDOM_H_