mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
synced 2024-11-15 00:16:48 +00:00
129 lines
4.5 KiB
C++
129 lines
4.5 KiB
C++
/*
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* Copyright (c) 2018-2019 Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <random>
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#include <stratosphere.hpp>
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namespace ams::rnd {
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namespace {
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/* Generator type. */
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/* Official HOS uses TinyMT. This is high effort. Let's just use XorShift. */
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/* https://en.wikipedia.org/wiki/Xorshift */
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class XorShiftGenerator {
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public:
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using ResultType = uint32_t;
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using result_type = ResultType;
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static constexpr ResultType (min)() { return std::numeric_limits<ResultType>::min(); }
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static constexpr ResultType (max)() { return std::numeric_limits<ResultType>::max(); }
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static constexpr size_t SeedSize = 4;
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private:
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ResultType random_state[SeedSize];
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public:
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explicit XorShiftGenerator() {
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/* Seed using process entropy. */
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u64 val = 0;
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for (size_t i = 0; i < SeedSize; i++) {
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R_ASSERT(svcGetInfo(&val, InfoType_RandomEntropy, INVALID_HANDLE, i));
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this->random_state[i] = ResultType(val);
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}
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}
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explicit XorShiftGenerator(std::random_device &rd) {
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for (size_t i = 0; i < SeedSize; i++) {
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this->random_state[i] = ResultType(rd());
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}
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}
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ResultType operator()() {
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ResultType s, t = this->random_state[3];
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t ^= t << 11;
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t ^= t >> 8;
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this->random_state[3] = this->random_state[2]; this->random_state[2] = this->random_state[1]; this->random_state[1] = (s = this->random_state[0]);
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t ^= s;
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t ^= s >> 19;
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this->random_state[0] = t;
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return t;
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}
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void discard(size_t n) {
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for (size_t i = 0; i < n; i++) {
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operator()();
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}
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}
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};
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/* Generator global. */
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XorShiftGenerator g_rnd_generator;
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/* Templated helpers. */
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template<typename T>
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T GenerateRandom(T max = std::numeric_limits<T>::max()) {
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std::uniform_int_distribution<T> rnd(std::numeric_limits<T>::min(), max);
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return rnd(g_rnd_generator);
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}
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}
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void GenerateRandomBytes(void* _out, size_t size) {
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uintptr_t out = reinterpret_cast<uintptr_t>(_out);
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uintptr_t end = out + size;
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/* Force alignment. */
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if (out % sizeof(u16) && out < end) {
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*reinterpret_cast<u8 *>(out) = GenerateRandom<u8>();
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out += sizeof(u8);
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}
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if (out % sizeof(u32) && out < end) {
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*reinterpret_cast<u16 *>(out) = GenerateRandom<u16>();
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out += sizeof(u16);
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}
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if (out % sizeof(u64) && out < end) {
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*reinterpret_cast<u32 *>(out) = GenerateRandom<u32>();
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out += sizeof(u32);
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}
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/* Perform as many aligned writes as possible. */
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while (out + sizeof(u64) <= end) {
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*reinterpret_cast<u64 *>(out) = GenerateRandom<u64>();
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out += sizeof(u64);
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}
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/* Do remainder writes. */
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if (out + sizeof(u32) <= end) {
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*reinterpret_cast<u32 *>(out) = GenerateRandom<u32>();
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out += sizeof(u32);
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}
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if (out + sizeof(u16) <= end) {
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*reinterpret_cast<u16 *>(out) = GenerateRandom<u16>();
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out += sizeof(u16);
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}
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if (out + sizeof(u8) <= end) {
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*reinterpret_cast<u8 *>(out) = GenerateRandom<u8>();
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out += sizeof(u8);
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}
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}
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u32 GenerateRandomU32(u32 max) {
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return GenerateRandom<u32>(max);
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}
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u64 GenerateRandomU64(u64 max) {
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return GenerateRandom<u64>(max);
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}
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}
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