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/*
* librd - Rapid Development C library
*
* Copyright (c) 2012, Magnus Edenhill
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. 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.
*
* 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 "rd.h"
#include "rdrand.h"
#include "rdtime.h"
#include "tinycthread.h"
int rd_jitter(int low, int high) {
int rand_num;
#if HAVE_RAND_R
static RD_TLS unsigned int seed = 0;
/* Initial seed with time+thread id */
if (unlikely(seed == 0)) {
struct timeval tv;
rd_gettimeofday(&tv, NULL);
seed = (unsigned int)(tv.tv_usec / 1000);
seed ^= (unsigned int)(intptr_t)thrd_current();
}
rand_num = rand_r(&seed);
#else
rand_num = rand();
#endif
return (low + (rand_num % ((high - low) + 1)));
}
void rd_array_shuffle(void *base, size_t nmemb, size_t entry_size) {
int i;
void *tmp = rd_alloca(entry_size);
/* FIXME: Optimized version for word-sized entries. */
for (i = (int)nmemb - 1; i > 0; i--) {
int j = rd_jitter(0, i);
if (unlikely(i == j))
continue;
memcpy(tmp, (char *)base + (i * entry_size), entry_size);
memcpy((char *)base + (i * entry_size),
(char *)base + (j * entry_size), entry_size);
memcpy((char *)base + (j * entry_size), tmp, entry_size);
}
}
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