Contiki-NG
random.c
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1 /*
2  * Copyright (c) 2020, Toshiba BRIL
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  * notice, this list of conditions and the following disclaimer in the
12  * documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the copyright holder nor the names of its
14  * contributors may be used to endorse or promote products derived
15  * from this software without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
20  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
21  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
24  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
26  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
28  * OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 /*---------------------------------------------------------------------------*/
31 /**
32  * \addtogroup nrf52840
33  * @{
34  *
35  * \addtogroup nrf52840-dev Device drivers
36  * @{
37  *
38  * \addtogroup nrf52840-rng Hardware random number generator
39  * @{
40  *
41  * \file
42  * Wrapper around rand() using the hardware RNG for seeding.
43  *
44  * This file overrides os/lib/random.c.
45  */
46 /*---------------------------------------------------------------------------*/
47 #include <stdlib.h>
48 #include <nrfx_rng.h>
49 /*---------------------------------------------------------------------------*/
50 unsigned short
52 {
53  return (unsigned short)rand();
54 }
55 /*---------------------------------------------------------------------------*/
56 /**
57 * \brief Initialize the libc random number generator from the hardware RNG.
58 * \param seed Ignored.
59 *
60 */
61 void
62 random_init(unsigned short seed)
63 {
64  (void)seed;
65  unsigned short hwrng = 0;
66  NRF_RNG->TASKS_START = 1;
67 
68  NRF_RNG->EVENTS_VALRDY = 0;
69  while(!NRF_RNG->EVENTS_VALRDY);
70  hwrng = (NRF_RNG->VALUE & 0xFF);
71 
72  NRF_RNG->EVENTS_VALRDY = 0;
73  while(!NRF_RNG->EVENTS_VALRDY);
74  hwrng |= ((NRF_RNG->VALUE & 0xFF) << 8);
75 
76  NRF_RNG->TASKS_STOP = 1;
77 
78  srand(hwrng);
79 }
80 /*---------------------------------------------------------------------------*/
81 /**
82  * @}
83  * @}
84  * @}
85  */
void random_init(unsigned short seed)
Seed the cc2538 random number generator.
Definition: random.c:84
unsigned short random_rand(void)
Generates a new random number using the cc2538 RNG.
Definition: random.c:58