1 // Copyright 2021 The Tint Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "fuzzers/mersenne_twister_engine.h"
16
17 #include <algorithm>
18 #include <cassert>
19
20 #include "src/utils/hash.h"
21
22 namespace tint {
23 namespace fuzzers {
24
25 namespace {
26
27 /// Generate integer from uniform distribution
28 /// @tparam I - integer type
29 /// @param engine - random number engine to use
30 /// @param lower - Lower bound of integer generated
31 /// @param upper - Upper bound of integer generated
32 /// @returns i, where lower <= i < upper
33 template <typename I>
RandomInteger(std::mt19937_64 * engine,I lower,I upper)34 I RandomInteger(std::mt19937_64* engine, I lower, I upper) {
35 assert(lower < upper && "|lower| must be strictly less than |upper|");
36 return std::uniform_int_distribution<I>(lower, upper - 1)(*engine);
37 }
38
39 } // namespace
40
MersenneTwisterEngine(uint64_t seed)41 MersenneTwisterEngine::MersenneTwisterEngine(uint64_t seed) : engine_(seed) {}
42
RandomUInt32(uint32_t lower,uint32_t upper)43 uint32_t MersenneTwisterEngine::RandomUInt32(uint32_t lower, uint32_t upper) {
44 return RandomInteger(&engine_, lower, upper);
45 }
46
RandomUInt64(uint64_t lower,uint64_t upper)47 uint64_t MersenneTwisterEngine::RandomUInt64(uint64_t lower, uint64_t upper) {
48 return RandomInteger(&engine_, lower, upper);
49 }
50
RandomNBytes(uint8_t * dest,size_t n)51 void MersenneTwisterEngine::RandomNBytes(uint8_t* dest, size_t n) {
52 assert(dest && "|dest| must not be nullptr");
53 std::generate(
54 dest, dest + n,
55 std::independent_bits_engine<std::mt19937_64, 8, uint8_t>(engine_));
56 }
57
58 } // namespace fuzzers
59 } // namespace tint
60