68 lines
2.5 KiB
C
68 lines
2.5 KiB
C
/*-
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* Portions Copyright (c) 2010, Intel Corporation. All rights reserved.<BR>
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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//__FBSDID("$FreeBSD: src/lib/libc/stdlib/rand.c,v 1.17.2.1.2.1 2009/10/25 01:10:29 kensmith Exp $");
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#include <LibConfig.h>
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#include <stdlib.h>
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static UINT32 next = 1;
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/** Compute a pseudo-random number.
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*
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* Compute x = (7^5 * x) mod (2^31 - 1)
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* without overflowing 31 bits:
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* (2^31 - 1) = 127773 * (7^5) + 2836
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* From "Random number generators: good ones are hard to find",
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* Park and Miller, Communications of the ACM, vol. 31, no. 10,
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* October 1988, p. 1195.
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**/
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int
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rand()
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{
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INT32 hi, lo, x;
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/* Can't be initialized with 0, so use another value. */
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if (next == 0)
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next = 123459876;
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hi = next / 127773;
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lo = next % 127773;
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x = 16807 * lo - 2836 * hi;
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if (x < 0)
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x += 0x7fffffff;
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return ((next = x) % ((UINT32)RAND_MAX + 1));
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}
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void
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srand(unsigned int seed)
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{
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next = (UINT32)seed;
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}
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