| 1 | /* Reentrant random function from POSIX.1c. |
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| 2 | Copyright (C) 1996-2022 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | #include <stdlib.h> |
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| 20 | |
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| 21 | |
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| 22 | /* This algorithm is mentioned in the ISO C standard, here extended |
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| 23 | for 32 bits. */ |
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| 24 | int |
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| 25 | rand_r (unsigned int *seed) |
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| 26 | { |
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| 27 | unsigned int next = *seed; |
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| 28 | int result; |
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| 29 | |
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| 30 | next *= 1103515245; |
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| 31 | next += 12345; |
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| 32 | result = (unsigned int) (next / 65536) % 2048; |
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| 33 | |
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| 34 | next *= 1103515245; |
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| 35 | next += 12345; |
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| 36 | result <<= 10; |
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| 37 | result ^= (unsigned int) (next / 65536) % 1024; |
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| 38 | |
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| 39 | next *= 1103515245; |
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| 40 | next += 12345; |
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| 41 | result <<= 10; |
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| 42 | result ^= (unsigned int) (next / 65536) % 1024; |
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| 43 | |
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| 44 | *seed = next; |
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| 45 | |
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| 46 | return result; |
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| 47 | } |
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| 48 | |
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