mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
synced 2024-11-30 15:52:15 +00:00
129 lines
4.5 KiB
C++
129 lines
4.5 KiB
C++
/*
|
|
* Copyright (c) 2018-2019 Atmosphère-NX
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms and conditions of the GNU General Public License,
|
|
* version 2, as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
|
* more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
#include <random>
|
|
#include <stratosphere.hpp>
|
|
|
|
namespace ams::rnd {
|
|
|
|
namespace {
|
|
|
|
/* Generator type. */
|
|
/* Official HOS uses TinyMT. This is high effort. Let's just use XorShift. */
|
|
/* https://en.wikipedia.org/wiki/Xorshift */
|
|
class XorShiftGenerator {
|
|
public:
|
|
using ResultType = uint32_t;
|
|
using result_type = ResultType;
|
|
static constexpr ResultType (min)() { return std::numeric_limits<ResultType>::min(); }
|
|
static constexpr ResultType (max)() { return std::numeric_limits<ResultType>::max(); }
|
|
static constexpr size_t SeedSize = 4;
|
|
private:
|
|
ResultType random_state[SeedSize];
|
|
public:
|
|
|
|
explicit XorShiftGenerator() {
|
|
/* Seed using process entropy. */
|
|
u64 val = 0;
|
|
for (size_t i = 0; i < SeedSize; i++) {
|
|
R_ASSERT(svcGetInfo(&val, InfoType_RandomEntropy, INVALID_HANDLE, i));
|
|
this->random_state[i] = ResultType(val);
|
|
}
|
|
}
|
|
|
|
explicit XorShiftGenerator(std::random_device &rd) {
|
|
for (size_t i = 0; i < SeedSize; i++) {
|
|
this->random_state[i] = ResultType(rd());
|
|
}
|
|
}
|
|
|
|
ResultType operator()() {
|
|
ResultType s, t = this->random_state[3];
|
|
t ^= t << 11;
|
|
t ^= t >> 8;
|
|
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]);
|
|
t ^= s;
|
|
t ^= s >> 19;
|
|
this->random_state[0] = t;
|
|
return t;
|
|
}
|
|
|
|
void discard(size_t n) {
|
|
for (size_t i = 0; i < n; i++) {
|
|
operator()();
|
|
}
|
|
}
|
|
};
|
|
|
|
/* Generator global. */
|
|
XorShiftGenerator g_rnd_generator;
|
|
|
|
/* Templated helpers. */
|
|
template<typename T>
|
|
T GenerateRandom(T max = std::numeric_limits<T>::max()) {
|
|
std::uniform_int_distribution<T> rnd(std::numeric_limits<T>::min(), max);
|
|
return rnd(g_rnd_generator);
|
|
}
|
|
|
|
}
|
|
|
|
void GenerateRandomBytes(void* _out, size_t size) {
|
|
uintptr_t out = reinterpret_cast<uintptr_t>(_out);
|
|
uintptr_t end = out + size;
|
|
|
|
/* Force alignment. */
|
|
if (out % sizeof(u16) && out < end) {
|
|
*reinterpret_cast<u8 *>(out) = GenerateRandom<u8>();
|
|
out += sizeof(u8);
|
|
}
|
|
if (out % sizeof(u32) && out < end) {
|
|
*reinterpret_cast<u16 *>(out) = GenerateRandom<u16>();
|
|
out += sizeof(u16);
|
|
}
|
|
if (out % sizeof(u64) && out < end) {
|
|
*reinterpret_cast<u32 *>(out) = GenerateRandom<u32>();
|
|
out += sizeof(u32);
|
|
}
|
|
|
|
/* Perform as many aligned writes as possible. */
|
|
while (out + sizeof(u64) <= end) {
|
|
*reinterpret_cast<u64 *>(out) = GenerateRandom<u64>();
|
|
out += sizeof(u64);
|
|
}
|
|
|
|
/* Do remainder writes. */
|
|
if (out + sizeof(u32) <= end) {
|
|
*reinterpret_cast<u32 *>(out) = GenerateRandom<u32>();
|
|
out += sizeof(u32);
|
|
}
|
|
if (out + sizeof(u16) <= end) {
|
|
*reinterpret_cast<u16 *>(out) = GenerateRandom<u16>();
|
|
out += sizeof(u16);
|
|
}
|
|
if (out + sizeof(u8) <= end) {
|
|
*reinterpret_cast<u8 *>(out) = GenerateRandom<u8>();
|
|
out += sizeof(u8);
|
|
}
|
|
}
|
|
|
|
u32 GenerateRandomU32(u32 max) {
|
|
return GenerateRandom<u32>(max);
|
|
}
|
|
|
|
u64 GenerateRandomU64(u64 max) {
|
|
return GenerateRandom<u64>(max);
|
|
}
|
|
|
|
}
|