1/* Copyright 2020 The TensorFlow Authors. All Rights Reserved.
2
3Licensed under the Apache License, Version 2.0 (the "License");
4you may not use this file except in compliance with the License.
5You may obtain a copy of the License at
6
7 http://www.apache.org/licenses/LICENSE-2.0
8
9Unless required by applicable law or agreed to in writing, software
10distributed under the License is distributed on an "AS IS" BASIS,
11WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12See the License for the specific language governing permissions and
13limitations under the License.
14==============================================================================*/
15
16#ifndef TENSORFLOW_CORE_FRAMEWORK_RNG_ALG_H_
17#define TENSORFLOW_CORE_FRAMEWORK_RNG_ALG_H_
18
19#include "tensorflow/core/platform/logging.h"
20
21namespace tensorflow {
22
23enum Algorithm {
24 // The Philox algorithm, as described in paper
25 // ['Parallel Random Numbers: As Easy as 1, 2, 3']
26 // (https://www.thesalmons.org/john/random123/papers/random123sc11.pdf)
27 RNG_ALG_PHILOX = 1,
28 // The ThreeFry algorithm, as described in paper
29 // ['Parallel Random Numbers: As Easy as 1, 2, 3']
30 // (https://www.thesalmons.org/john/random123/papers/random123sc11.pdf)
31 RNG_ALG_THREEFRY = 2,
32 // An algorithm auto-selected by the system according to device type.
33 RNG_ALG_AUTO_SELECT = 3
34};
35
36// Same as `Algorithm`, but without AUTO_SELECT. We use C++ compiler's -Wswitch
37// and -Werror to check that `switch` covers all cases. When the algorithm
38// auto-selection has been resolved, we use this type so that
39// we don't need to (unnecessarily) handle the AUTO_SELECT case.
40enum class ConcreteRngAlgorithm {
41 RNG_ALG_PHILOX = 1,
42 RNG_ALG_THREEFRY = 2,
43};
44
45// Gets the counter size (in unit of uint64) for a counter-based RNG
46// algorithm `alg`. Callers of this function must ensure that `alg` doesn't have
47// non-enumerator values.
48inline int GetCounterSize(ConcreteRngAlgorithm alg) {
49 switch (alg) {
50 case ConcreteRngAlgorithm::RNG_ALG_PHILOX:
51 return 2;
52 case ConcreteRngAlgorithm::RNG_ALG_THREEFRY:
53 return 1;
54 }
55 LOG(ERROR) << "This point shouldn't have been reached.";
56}
57static constexpr int RNG_MAX_COUNTER_SIZE = 2;
58
59static constexpr int RNG_KEY_SIZE = 1;
60
61} // end namespace tensorflow
62
63#endif // TENSORFLOW_CORE_FRAMEWORK_RNG_ALG_H_
64