1 /*
2  * Copyright (C) 2017 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef CHRE_WIFI_OFFLOAD_TEST_RANDOM_GENERATOR_H_
18 #define CHRE_WIFI_OFFLOAD_TEST_RANDOM_GENERATOR_H_
19 
20 #include <cinttypes>
21 #include <random>
22 
23 namespace wifi_offload_test {
24 
25 /**
26  * @class RandomGenerator A class to generate random values for any uint type:
27  *        (uint8_t, ..., uint64_t). Also supports resetting to its initial
28  *        state to be able to reproduce the same random sequence.
29  */
30 class RandomGenerator {
31  public:
32   /**
33    * Default constructs a RandomGenerator object
34    */
35   RandomGenerator();
36 
37   /**
38    * Resets the object to its initial state. Useful if we want to reproduce the
39    * exact same sequenct again.
40    */
41   void Reset();
42 
43   /**
44    * Generates a random number of type IntType
45    *
46    * @return A random number of type IntType
47    */
48   template <typename IntType>
get()49   IntType get() {
50     return static_cast<IntType>(uniform_distribution_(random_engine_));
51   }
52 
53  private:
54   /* The initial seed kept to use again when need to reset  */
55   std::random_device::result_type initial_seed_;
56 
57   /* Standard mersenne_twister_engine */
58   std::mt19937 random_engine_;
59 
60   /**
61    * Use uniform_distribution_ to transform the random unsigned int generated by
62    * random_engine_ into an uint64_t
63    */
64   std::uniform_int_distribution<uint64_t> uniform_distribution_;
65 };
66 
67 }  // namespace wifi_offload_test
68 
69 #endif  // CHRE_WIFI_OFFLOAD_TEST_RANDOM_GENERATOR_H_
70