/*
* Copyright (c) 2018 Jiri Svoboda
* 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
/** @addtogroup libc
* @{
*/
/**
* @file
* @brief Random number generator.
*
* Generate random (as opposed to pseudorandom) numbers. This should be
* used sparingly (e.g. to seed a pseudorandom number generator).
*/
#include <errno.h>
#include <rndgen.h>
#include <stdint.h>
#include <stdlib.h>
#include <time.h>
/** Create random number generator.
*
* @param rrndgen Place to store new random number generator
* @return EOK on success or error code
*/
errno_t rndgen_create(rndgen_t **rrndgen)
{
rndgen_t *rndgen;
struct timespec ts;
rndgen = calloc(1, sizeof(rndgen_t));
if (rndgen == NULL)
return ENOMEM;
/* XXX This is a rather poor way of generating random numbers */
getuptime(&ts);
rndgen->seed = ts.tv_sec ^ ts.tv_nsec;
*rrndgen = rndgen;
return EOK;
}
/** Destroy random number generator.
*
* @param rndgen Random number generator or @c NULL
*/
void rndgen_destroy(rndgen_t *rndgen)
{
if (rndgen == NULL)
return;
free(rndgen);
}
/** Generate random 8-bit integer.
*
* @param rndgen Random number generator
* @param rb Place to store random 8-bit integer
* @return EOK on success or error code
*/
errno_t rndgen_uint8(rndgen_t *rndgen, uint8_t *rb)
{
rndgen->seed = (1366 * rndgen->seed + 150889) % 714025;
*rb = rndgen->seed & 0xff;
return EOK;
}
/** Generate random 16-bit integer.
*
* @param rndgen Random number generator
* @param rw Place to store random 16-bit integer
* @return EOK on success or error code
*/
errno_t rndgen_uint16(rndgen_t *rndgen, uint16_t *rw)
{
int i;
uint8_t b;
uint16_t w;
errno_t rc;
w = 0;
for (i = 0; i < 2; i++) {
rc = rndgen_uint8(rndgen, &b);
if (rc != EOK)
return rc;
w = (w << 8) | b;
}
*rw = w;
return EOK;
}
/** Generate random 32-bit integer.
*
* @param rndgen Random number generator
* @param rw Place to store random 32-bit integer
* @return EOK on success or error code
*/
errno_t rndgen_uint32(rndgen_t *rndgen, uint32_t *rw)
{
int i;
uint8_t b;
uint32_t w;
errno_t rc;
w = 0;
for (i = 0; i < 4; i++) {
rc = rndgen_uint8(rndgen, &b);
if (rc != EOK)
return rc;
w = (w << 8) | b;
}
*rw = w;
return EOK;
}
/** @}
*/