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/* M-runtime for c++
* Copyright (C) 2005-2008 Vladimir Menshakov
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "random.h"
#include <time.h>
#include "serializator.h"
#ifdef _WINDOWS
# ifndef uint64_t
# define uint64_t unsigned __int64
# endif
# ifndef uint32_t
# define uint32_t unsigned __int32
# endif
# ifndef uint16_t
# define uint16_t unsigned __int16
# endif
#else
# include <stdint.h>
#endif
#include <assert.h>
static uint32_t mrt_rand_seed;
//LPRG
#if 0
static uint32_t rand_impl() {
uint64_t x = mrt_rand_seed;
x *= 279470273;
x %= 4294967291U;
mrt_rand_seed = (uint32_t)x;
return x;
}
#endif
#if 1
//LFSR
static uint32_t rand_impl() {
return mrt_rand_seed = (mrt_rand_seed >> 1) ^ (-(mrt_rand_seed & 1u) & 0xd0000001u); /* taps 32 31 29 1 */
}
#endif
//#include "logger.h"
const int mrt::random(const unsigned max) {
if (max < 2)
return 0;
// int bits;
// unsigned m = max;
// for(bits = 1; m >>= 1; ++bits);
// bits = (32 - bits) / 2; //take middle bits of the generated number
unsigned x = rand_impl();
/*
unsigned len, n = max;
for(len = 0; n != 0; n >>= 1, ++len);
assert(len > 0 && len <= 32);
len = (32 - len);
//LOG_DEBUG(("random len: %u for maximum %u", len, max));
//LOG_DEBUG(("random number: 0x%08x, shifted: %u, max: %u", x, x >> len, max));
x >>= len;
*/
//x = (x >> bits) % max;
x %= max;
//LOG_DEBUG(("result: %u of %d, bits: %d", x, max, bits));
return (int)x;
}
void mrt::init_seed() {
mrt_rand_seed = time(NULL); //fixme!
}
void mrt::random_serialize(Serializator &s) {
s.add((unsigned)mrt_rand_seed);
}
void mrt::random_deserialize(const Serializator &s) {
unsigned x;
s.get(x);
mrt_rand_seed = x;
}
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