69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// <random>
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// template <class UIntType, UIntType a, UIntType c, UIntType m>
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// class linear_congruential_engine;
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// result_type operator()();
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#include <random>
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#include <cassert>
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#include "test_macros.h"
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int main(int, char**)
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{
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typedef unsigned long long T;
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// m might overflow, but the overflow is OK so it shouldn't use schrage's algorithm
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typedef std::linear_congruential_engine<T, 25214903917ull, 1, (1ull<<48)> E1;
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E1 e1;
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// make sure the right algorithm was used
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assert(e1() == 25214903918);
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assert(e1() == 205774354444503);
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assert(e1() == 158051849450892);
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// make sure result is in bounds
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assert(e1() < (1ull<<48));
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assert(e1() < (1ull<<48));
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assert(e1() < (1ull<<48));
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assert(e1() < (1ull<<48));
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assert(e1() < (1ull<<48));
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// m might overflow. The overflow is not OK and result will be in bounds
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// so we should use shrage's algorithm
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typedef std::linear_congruential_engine<T, (1ull<<2), 0, (1ull<<63) + 1> E2;
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E2 e2;
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// make sure shrage's algorithm is used (it would be 0s otherwise)
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assert(e2() == 4);
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assert(e2() == 16);
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assert(e2() == 64);
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// make sure result is in bounds
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assert(e2() < (1ull<<48) + 1);
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assert(e2() < (1ull<<48) + 1);
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assert(e2() < (1ull<<48) + 1);
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assert(e2() < (1ull<<48) + 1);
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assert(e2() < (1ull<<48) + 1);
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// m will not overflow so we should not use shrage's algorithm
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typedef std::linear_congruential_engine<T, 1ull, 1, (1ull<<48)> E3;
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E3 e3;
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// make sure the correct algorithm was used
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assert(e3() == 2);
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assert(e3() == 3);
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assert(e3() == 4);
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// make sure result is in bounds
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assert(e3() < (1ull<<48));
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assert(e3() < (1ull<<48));
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assert(e3() < (1ull<<48));
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assert(e3() < (1ull<<48));
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assert(e2() < (1ull<<48));
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return 0;
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} |