nes-proj/arch/cpu/simplelink-cc13xx-cc26xx/dev/random.c
2018-08-31 11:06:31 +02:00

102 lines
3.5 KiB
C

/*
* Copyright (c) 2018, Texas Instruments Incorporated - http://www.ti.com/
* 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.
* 3. Neither the name of the copyright holder 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 HOLDER 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.
*/
/**
* \addtogroup cc13xx-cc26xx-cpu
* @{
*
* \defgroup cc13xx-cc26xx-prng Pseudo Random Number Generator (PRNG) for CC13xx/CC26xx.
* @{
*
* Implementation based on Bob Jenkins' small noncryptographic PRNG.
* - http://burtleburtle.net/bob/rand/smallprng.html
*
* This file overrides os/lib/random.c. Note that the file name must
* match the original file for the override to work.
*
* \file
* Implementation of Pseudo Random Number Generator for CC13xx/CC26xx.
* \author
* Edvard Pettersen <e.pettersen@ti.com>
*/
/*---------------------------------------------------------------------------*/
#include <contiki.h>
/*---------------------------------------------------------------------------*/
#include <stdint.h>
/*---------------------------------------------------------------------------*/
typedef struct {
uint32_t a;
uint32_t b;
uint32_t c;
uint32_t d;
} ranctx_t;
static ranctx_t ranctx;
/*---------------------------------------------------------------------------*/
#define rot32(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
/*---------------------------------------------------------------------------*/
/**
* \brief Generates a new random number using the PRNG.
* \return The random number.
*/
unsigned short
random_rand(void)
{
uint32_t e;
e = ranctx.a - rot32(ranctx.b, 27);
ranctx.a = ranctx.b ^ rot32(ranctx.c, 17);
ranctx.b = ranctx.c + ranctx.d;
ranctx.c = ranctx.d + e;
ranctx.d = e + ranctx.a;
return (unsigned short)ranctx.d;
}
/*---------------------------------------------------------------------------*/
/**
* \brief Initialize the PRNG.
* \param seed Seed for the PRNG.
*/
void
random_init(unsigned short seed)
{
uint32_t i;
ranctx.a = 0xf1ea5eed;
ranctx.b = ranctx.c = ranctx.d = (uint32_t)seed;
for(i = 0; i < 20; ++i) {
(void)random_rand();
}
}
/*---------------------------------------------------------------------------*/
/**
* @}
* @}
*/