60 lines
1.9 KiB
C++
60 lines
1.9 KiB
C++
// Copyright 2021 The Tint Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "fuzzers/mersenne_twister_engine.h"
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#include <algorithm>
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#include <cassert>
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#include "src/utils/hash.h"
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namespace tint {
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namespace fuzzers {
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namespace {
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/// Generate integer from uniform distribution
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/// @tparam I - integer type
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/// @param engine - random number engine to use
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/// @param lower - Lower bound of integer generated
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/// @param upper - Upper bound of integer generated
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/// @returns i, where lower <= i < upper
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template <typename I>
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I RandomInteger(std::mt19937_64* engine, I lower, I upper) {
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assert(lower < upper && "|lower| must be strictly less than |upper|");
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return std::uniform_int_distribution<I>(lower, upper - 1)(*engine);
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}
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} // namespace
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MersenneTwisterEngine::MersenneTwisterEngine(uint64_t seed) : engine_(seed) {}
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uint32_t MersenneTwisterEngine::RandomUInt32(uint32_t lower, uint32_t upper) {
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return RandomInteger(&engine_, lower, upper);
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}
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uint64_t MersenneTwisterEngine::RandomUInt64(uint64_t lower, uint64_t upper) {
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return RandomInteger(&engine_, lower, upper);
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}
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void MersenneTwisterEngine::RandomNBytes(uint8_t* dest, size_t n) {
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assert(dest && "|dest| must not be nullptr");
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std::generate(
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dest, dest + n,
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std::independent_bits_engine<std::mt19937_64, 8, uint8_t>(engine_));
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}
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} // namespace fuzzers
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} // namespace tint
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