10b57cec5SDimitry Andric //===- FuzzerRandom.h - Internal header for the Fuzzer ----------*- C++ -* ===//
20b57cec5SDimitry Andric //
30b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
40b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
50b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
60b57cec5SDimitry Andric //
70b57cec5SDimitry Andric //===----------------------------------------------------------------------===//
80b57cec5SDimitry Andric // fuzzer::Random
90b57cec5SDimitry Andric //===----------------------------------------------------------------------===//
100b57cec5SDimitry Andric 
110b57cec5SDimitry Andric #ifndef LLVM_FUZZER_RANDOM_H
120b57cec5SDimitry Andric #define LLVM_FUZZER_RANDOM_H
130b57cec5SDimitry Andric 
140b57cec5SDimitry Andric #include <random>
150b57cec5SDimitry Andric 
160b57cec5SDimitry Andric namespace fuzzer {
170b57cec5SDimitry Andric class Random : public std::minstd_rand {
180b57cec5SDimitry Andric  public:
Random(unsigned int seed)190b57cec5SDimitry Andric   Random(unsigned int seed) : std::minstd_rand(seed) {}
operator()200b57cec5SDimitry Andric   result_type operator()() { return this->std::minstd_rand::operator()(); }
210b57cec5SDimitry Andric   template <typename T>
Rand()220b57cec5SDimitry Andric   typename std::enable_if<std::is_integral<T>::value, T>::type Rand() {
230b57cec5SDimitry Andric     return static_cast<T>(this->operator()());
240b57cec5SDimitry Andric   }
RandBool()250b57cec5SDimitry Andric   size_t RandBool() { return this->operator()() % 2; }
SkewTowardsLast(size_t n)260b57cec5SDimitry Andric   size_t SkewTowardsLast(size_t n) {
270b57cec5SDimitry Andric     size_t T = this->operator()(n * n);
280b57cec5SDimitry Andric     size_t Res = static_cast<size_t>(sqrt(T));
290b57cec5SDimitry Andric     return Res;
300b57cec5SDimitry Andric   }
310b57cec5SDimitry Andric   template <typename T>
operator()320b57cec5SDimitry Andric   typename std::enable_if<std::is_integral<T>::value, T>::type operator()(T n) {
330b57cec5SDimitry Andric     return n ? Rand<T>() % n : 0;
340b57cec5SDimitry Andric   }
350b57cec5SDimitry Andric   template <typename T>
360b57cec5SDimitry Andric   typename std::enable_if<std::is_integral<T>::value, T>::type
operator()370b57cec5SDimitry Andric   operator()(T From, T To) {
380b57cec5SDimitry Andric     assert(From < To);
39     auto RangeSize = static_cast<unsigned long long>(To) -
40                      static_cast<unsigned long long>(From) + 1;
41     return static_cast<T>(this->operator()(RangeSize) + From);
42   }
43 };
44 
45 }  // namespace fuzzer
46 
47 #endif  // LLVM_FUZZER_RANDOM_H
48