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/*
* Copyright (c) 2009-2016, Albertas Vyšniauskas
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* * Neither the name of the software author nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "Random.h"
#include <string.h>
static unsigned long random_function_znew(struct Random* r, unsigned long seed_offset)
{
return (r->seed[seed_offset] = 36969 * (r->seed[seed_offset] & 65535) + (r->seed[seed_offset] >> 16));
}
static unsigned long random_function_wnew(struct Random* r, unsigned long seed_offset)
{
return (r->seed[seed_offset] = 18000 * (r->seed[seed_offset] & 65535) + (r->seed[seed_offset] >> 16));
}
static unsigned long random_function_MWC(struct Random* r, unsigned long seed_offset)
{
return (random_function_znew(r, 0) << 16) + random_function_wnew(r, 1);
}
static unsigned long random_function_SHR3(struct Random* r, unsigned long seed_offset)
{
r->seed[seed_offset] ^= r->seed[seed_offset] << 17;
r->seed[seed_offset] ^= (r->seed[seed_offset] & 0xFFFFFFFF) >> 13;
return (r->seed[seed_offset] ^= r->seed[seed_offset] << 5);
}
struct Random* random_new(const char* random_function)
{
struct Random* r = new struct Random;
struct RandomFunction
{
const char* name;
unsigned long (*function)(struct Random* r, unsigned long seed_offset);
unsigned long seed_size;
};
struct RandomFunction functions[] = {
{"znew", random_function_znew, 1},
{"wnew", random_function_wnew, 1},
{"MWC", random_function_MWC, 2},
{"SHR3", random_function_SHR3, 1},
};
bool found = false;
for (unsigned long i = 0; i < sizeof(functions) / sizeof(struct RandomFunction); ++i){
if (strcmp(random_function, functions[i].name) == 0){
r->function = functions[i].function;
r->seed_size = functions[i].seed_size;
r->seed = new unsigned long [r->seed_size];
found = true;
break;
}
}
if (found) return r;
delete r;
return 0;
}
struct Random* random_new(const char* random_function, unsigned long seed)
{
struct Random* random = random_new(random_function);
random_seed(random, &seed);
random_get(random);
return random;
}
unsigned long random_get(struct Random* r)
{
if (!r) return 0;
return r->function(r, 0);
}
double random_get_double(struct Random* r)
{
return (random_get(r) & 0xFFFFFFFF) / (double)0xFFFFFFFF;
}
void random_seed(struct Random* r, void* seed)
{
if (!r) return;
memcpy(r->seed, seed, r->seed_size * sizeof(unsigned long));
}
void random_destroy(struct Random* r)
{
if (r){
delete [] r->seed;
delete r;
}
}
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