| 1 | //===-- Implementation of rand --------------------------------------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #include "src/stdlib/rand.h" |
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| 10 | #include "src/__support/common.h" |
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| 11 | #include "src/stdlib/rand_util.h" |
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| 12 | |
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| 13 | namespace LIBC_NAMESPACE { |
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| 14 | |
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| 15 | // An implementation of the xorshift64star pseudo random number generator. This |
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| 16 | // is a good general purpose generator for most non-cryptographics applications. |
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| 17 | LLVM_LIBC_FUNCTION(int, rand, (void)) { |
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| 18 | unsigned long x = rand_next; |
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| 19 | x ^= x >> 12; |
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| 20 | x ^= x << 25; |
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| 21 | x ^= x >> 27; |
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| 22 | rand_next = x; |
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| 23 | return static_cast<int>((x * 0x2545F4914F6CDD1Dul) >> 32) & RAND_MAX; |
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| 24 | } |
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| 25 | |
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| 26 | } // namespace LIBC_NAMESPACE |
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| 27 | |
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