47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
/*
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* Copyright (c) 1993 Martin Birgmeier
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* All rights reserved.
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*
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* You may redistribute unmodified or modified versions of this source
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* code provided that the above copyright notice and this and the
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* following conditions are retained.
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*
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* This software is provided ``as is'', and comes with no warranties
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* of any kind. I shall in no event be liable for anything that happens
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* to anyone/anything when using this software.
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*/
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#include "rand48.h"
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unsigned short _rand48_seed[3] = {
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RAND48_SEED_0,
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RAND48_SEED_1,
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RAND48_SEED_2
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};
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unsigned short _rand48_mult[3] = {
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RAND48_MULT_0,
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RAND48_MULT_1,
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RAND48_MULT_2
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};
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unsigned short _rand48_add = RAND48_ADD;
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void
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_dorand48(unsigned short xseed[3])
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{
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unsigned long accu;
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unsigned short temp[2];
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accu = (unsigned long) _rand48_mult[0] * (unsigned long) xseed[0] +
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(unsigned long) _rand48_add;
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temp[0] = (unsigned short) accu; /* lower 16 bits */
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accu >>= sizeof(unsigned short) * 8;
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accu += (unsigned long) _rand48_mult[0] * (unsigned long) xseed[1] +
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(unsigned long) _rand48_mult[1] * (unsigned long) xseed[0];
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temp[1] = (unsigned short) accu; /* middle 16 bits */
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accu >>= sizeof(unsigned short) * 8;
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accu += _rand48_mult[0] * xseed[2] + _rand48_mult[1] * xseed[1] + _rand48_mult[2] * xseed[0];
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xseed[0] = temp[0];
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xseed[1] = temp[1];
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xseed[2] = (unsigned short) accu;
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}
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