compiler-rt/lib/fuzzer/FuzzerRandom.h

   1 //===- FuzzerRandom.h - Internal header for the Fuzzer ----------*- C++ -* ===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 // fuzzer::Random
   9 //===----------------------------------------------------------------------===//
  10
  11 #ifndef LLVM_FUZZER_RANDOM_H
  12 #define LLVM_FUZZER_RANDOM_H
  13
  14 #include <random>
  15
  16 namespace fuzzer {
  17 class Random : public std::minstd_rand {
  18  public:
  19   Random(unsigned int seed) : std::minstd_rand(seed) {}
  20   result_type operator()() { return this->std::minstd_rand::operator()(); }
  21   size_t Rand() { return this->operator()(); }
  22   size_t RandBool() { return Rand() % 2; }
  23   size_t SkewTowardsLast(size_t n) {
  24     size_t T = this->operator()(n * n);
  25     size_t Res = sqrt(T);
  26     return Res;
  27   }
  28   size_t operator()(size_t n) { return n ? Rand() % n : 0; }
  29   intptr_t operator()(intptr_t From, intptr_t To) {
  30     assert(From < To);
  31     intptr_t RangeSize = To - From + 1;
  32     return operator()(RangeSize) + From;
  33   }
  34 };
  35
  36 }  // namespace fuzzer
  37
  38 #endif  // LLVM_FUZZER_RANDOM_H