Add xoroshiro128++ PRNG

Xoroshiro128++ is a fast non-cryptographic random generator.
Reference implementation is available at https://prng.di.unimi.it/

Co-Authored-By: Pieter Wuille <[email protected]>

Author: martinus

src/Makefile.test.include

@@ -162,7 +162,8 @@ BITCOIN_TESTS =\
   test/validation_flush_tests.cpp \
   test/validation_tests.cpp \
   test/validationinterface_tests.cpp \
-  test/versionbits_tests.cpp
+  test/versionbits_tests.cpp \
+  test/xoroshiro128plusplus_tests.cpp
 
 if ENABLE_WALLET
 BITCOIN_TESTS += \

src/Makefile.test_util.include

@@ -18,7 +18,8 @@ TEST_UTIL_H = \
   test/util/str.h \
   test/util/transaction_utils.h \
   test/util/txmempool.h \
-  test/util/validation.h
+  test/util/validation.h \
+  test/util/xoroshiro128plusplus.h
 
 if ENABLE_WALLET
 TEST_UTIL_H += wallet/test/util.h

src/test/util/xoroshiro128plusplus.h

@@ -0,0 +1,71 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_TEST_UTIL_XOROSHIRO128PLUSPLUS_H
+#define BITCOIN_TEST_UTIL_XOROSHIRO128PLUSPLUS_H
+
+#include <cstdint>
+#include <limits>
+
+/** xoroshiro128++ PRNG. Extremely fast, not appropriate for cryptographic purposes.
+ *
+ * Memory footprint is 128bit, period is 2^128 - 1.
+ * This class is not thread-safe.
+ *
+ * Reference implementation available at https://prng.di.unimi.it/xoroshiro128plusplus.c
+ * See https://prng.di.unimi.it/
+ */
+class XoRoShiRo128PlusPlus
+{
+    uint64_t m_s0;
+    uint64_t m_s1;
+
+    [[nodiscard]] constexpr static uint64_t rotl(uint64_t x, int n)
+    {
+        return (x << n) | (x >> (64 - n));
+    }
+
+    [[nodiscard]] constexpr static uint64_t SplitMix64(uint64_t& seedval) noexcept
+    {
+        uint64_t z = (seedval += UINT64_C(0x9e3779b97f4a7c15));
+        z = (z ^ (z >> 30U)) * UINT64_C(0xbf58476d1ce4e5b9);
+        z = (z ^ (z >> 27U)) * UINT64_C(0x94d049bb133111eb);
+        return z ^ (z >> 31U);
+    }
+
+public:
+    using result_type = uint64_t;
+
+    constexpr explicit XoRoShiRo128PlusPlus(uint64_t seedval) noexcept
+        : m_s0(SplitMix64(seedval)), m_s1(SplitMix64(seedval))
+    {
+    }
+
+    // no copy - that is dangerous, we don't want accidentally copy the RNG and then have two streams
+    // with exactly the same results. If you need a copy, call copy().
+    XoRoShiRo128PlusPlus(const XoRoShiRo128PlusPlus&) = delete;
+    XoRoShiRo128PlusPlus& operator=(const XoRoShiRo128PlusPlus&) = delete;
+
+    // allow moves
+    XoRoShiRo128PlusPlus(XoRoShiRo128PlusPlus&&) = default;
+    XoRoShiRo128PlusPlus& operator=(XoRoShiRo128PlusPlus&&) = default;
+
+    ~XoRoShiRo128PlusPlus() = default;
+
+    constexpr result_type operator()() noexcept
+    {
+        uint64_t s0 = m_s0, s1 = m_s1;
+        const uint64_t result = rotl(s0 + s1, 17) + s0;
+        s1 ^= s0;
+        m_s0 = rotl(s0, 49) ^ s1 ^ (s1 << 21);
+        m_s1 = rotl(s1, 28);
+        return result;
+    }
+
+    static constexpr result_type min() noexcept { return std::numeric_limits<result_type>::min(); }
+    static constexpr result_type max() noexcept { return std::numeric_limits<result_type>::max(); }
+    static constexpr double entropy() noexcept { return 0.0; }
+};
+
+#endif // BITCOIN_TEST_UTIL_XOROSHIRO128PLUSPLUS_H

src/test/xoroshiro128plusplus_tests.cpp

@@ -0,0 +1,29 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <test/util/setup_common.h>
+#include <test/util/xoroshiro128plusplus.h>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(xoroshiro128plusplus_tests, BasicTestingSetup)
+
+BOOST_AUTO_TEST_CASE(reference_values)
+{
+    // numbers generated from reference implementation
+    XoRoShiRo128PlusPlus rng(0);
+    BOOST_TEST(0x6f68e1e7e2646ee1 == rng());
+    BOOST_TEST(0xbf971b7f454094ad == rng());
+    BOOST_TEST(0x48f2de556f30de38 == rng());
+    BOOST_TEST(0x6ea7c59f89bbfc75 == rng());
+
+    // seed with a random number
+    rng = XoRoShiRo128PlusPlus(0x1a26f3fa8546b47a);
+    BOOST_TEST(0xc8dc5e08d844ac7d == rng());
+    BOOST_TEST(0x5b5f1f6d499dad1b == rng());
+    BOOST_TEST(0xbeb0031f93313d6f == rng());
+    BOOST_TEST(0xbfbcf4f43a264497 == rng());
+}
+
+BOOST_AUTO_TEST_SUITE_END()

test/sanitizer_suppressions/ubsan

@@ -53,6 +53,7 @@ unsigned-integer-overflow:policy/fees.cpp
 unsigned-integer-overflow:prevector.h
 unsigned-integer-overflow:script/interpreter.cpp
 unsigned-integer-overflow:txmempool.cpp
+unsigned-integer-overflow:xoroshiro128plusplus.h
 implicit-integer-sign-change:compat/stdin.cpp
 implicit-integer-sign-change:compressor.h
 implicit-integer-sign-change:crypto/
@@ -69,3 +70,4 @@ shift-base:crypto/
 shift-base:hash.cpp
 shift-base:streams.h
 shift-base:util/bip32.cpp
+shift-base:xoroshiro128plusplus.h