102 lines
3.5 KiB
C
102 lines
3.5 KiB
C
/*
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* Copyright (c) 2018, Texas Instruments Incorporated - http://www.ti.com/
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \addtogroup cc13xx-cc26xx-cpu
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* @{
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*
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* \defgroup cc13xx-cc26xx-prng Pseudo Random Number Generator (PRNG) for CC13xx/CC26xx.
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* @{
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*
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* Implementation based on Bob Jenkins' small noncryptographic PRNG.
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* - http://burtleburtle.net/bob/rand/smallprng.html
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*
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* This file overrides os/lib/random.c. Note that the file name must
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* match the original file for the override to work.
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*
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* \file
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* Implementation of Pseudo Random Number Generator for CC13xx/CC26xx.
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* \author
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* Edvard Pettersen <e.pettersen@ti.com>
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*/
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/*---------------------------------------------------------------------------*/
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#include <contiki.h>
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/*---------------------------------------------------------------------------*/
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#include <stdint.h>
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/*---------------------------------------------------------------------------*/
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typedef struct {
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uint32_t a;
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uint32_t b;
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uint32_t c;
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uint32_t d;
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} ranctx_t;
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static ranctx_t ranctx;
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/*---------------------------------------------------------------------------*/
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#define rot32(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Generates a new random number using the PRNG.
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* \return The random number.
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*/
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unsigned short
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random_rand(void)
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{
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uint32_t e;
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e = ranctx.a - rot32(ranctx.b, 27);
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ranctx.a = ranctx.b ^ rot32(ranctx.c, 17);
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ranctx.b = ranctx.c + ranctx.d;
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ranctx.c = ranctx.d + e;
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ranctx.d = e + ranctx.a;
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return (unsigned short)ranctx.d;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Initialize the PRNG.
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* \param seed Seed for the PRNG.
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*/
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void
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random_init(unsigned short seed)
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{
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uint32_t i;
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ranctx.a = 0xf1ea5eed;
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ranctx.b = ranctx.c = ranctx.d = (uint32_t)seed;
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for(i = 0; i < 20; ++i) {
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(void)random_rand();
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}
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}
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/*---------------------------------------------------------------------------*/
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/**
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* @}
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* @}
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*/
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