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/*-------------------------------------------------------------------------
*
* rand.c
* Missing rand implementations for Win32
*
*-------------------------------------------------------------------------
*/
#include "c.h"
/*
* Copyright (c) 1993 Martin Birgmeier
* All rights reserved.
*
* You may redistribute unmodified or modified versions of this source
* code provided that the above copyright notice and this and the
* following conditions are retained.
*
* This software is provided ``as is'', and comes with no warranties
* of any kind. I shall in no event be liable for anything that happens
* to anyone/anything when using this software.
*/
#define RAND48_SEED_0 (0x330e)
#define RAND48_SEED_1 (0xabcd)
#define RAND48_SEED_2 (0x1234)
#define RAND48_MULT_0 (0xe66d)
#define RAND48_MULT_1 (0xdeec)
#define RAND48_MULT_2 (0x0005)
#define RAND48_ADD (0x000b)
unsigned short _rand48_seed[3] = {
RAND48_SEED_0,
RAND48_SEED_1,
RAND48_SEED_2
};
unsigned short _rand48_mult[3] = {
RAND48_MULT_0,
RAND48_MULT_1,
RAND48_MULT_2
};
unsigned short _rand48_add = RAND48_ADD;
static void
_dorand48(unsigned short xseed[3])
{
unsigned long accu;
unsigned short temp[2];
accu = (unsigned long) _rand48_mult[0] * (unsigned long) xseed[0] +
(unsigned long) _rand48_add;
temp[0] = (unsigned short) accu; /* lower 16 bits */
accu >>= sizeof(unsigned short) * 8;
accu += (unsigned long) _rand48_mult[0] * (unsigned long) xseed[1] +
(unsigned long) _rand48_mult[1] * (unsigned long) xseed[0];
temp[1] = (unsigned short) accu; /* middle 16 bits */
accu >>= sizeof(unsigned short) * 8;
accu += _rand48_mult[0] * xseed[2] + _rand48_mult[1] * xseed[1] + _rand48_mult[2] * xseed[0];
xseed[0] = temp[0];
xseed[1] = temp[1];
xseed[2] = (unsigned short) accu;
}
long
lrand48(void)
{
_dorand48(_rand48_seed);
return ((long) _rand48_seed[2] << 15) + ((long) _rand48_seed[1] >> 1);
}
void
srand48(long seed)
{
_rand48_seed[0] = RAND48_SEED_0;
_rand48_seed[1] = (unsigned short) seed;
_rand48_seed[2] = (unsigned short) (seed >> 16);
_rand48_mult[0] = RAND48_MULT_0;
_rand48_mult[1] = RAND48_MULT_1;
_rand48_mult[2] = RAND48_MULT_2;
_rand48_add = RAND48_ADD;
}
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