1//===-- random.cpp ----------------------------------------------*- 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 9#include "gwp_asan/random.h" 10#include "gwp_asan/common.h" 11 12#include <time.h> 13 14// Initialised to a magic constant so that an uninitialised GWP-ASan won't 15// regenerate its sample counter for as long as possible. The xorshift32() 16// algorithm used below results in getRandomUnsigned32(0xff82eb50) == 17// 0xfffffea4. 18GWP_ASAN_TLS_INITIAL_EXEC uint32_t RandomState = 0xff82eb50; 19 20namespace gwp_asan { 21void initPRNG() { 22 RandomState = time(nullptr) + getThreadID(); 23} 24 25uint32_t getRandomUnsigned32() { 26 RandomState ^= RandomState << 13; 27 RandomState ^= RandomState >> 17; 28 RandomState ^= RandomState << 5; 29 return RandomState; 30} 31} // namespace gwp_asan 32