112 lines
4.0 KiB
C
112 lines
4.0 KiB
C
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/*
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* Copyright (c) 2011, George Oikonomou - <oikonomou@users.sourceforge.net>
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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 Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR 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, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*/
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/**
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* \file
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* Random number generator routines exploiting the cc2530 hardware
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* capabilities.
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*
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* This file overrides core/lib/random.c.
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*
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* \author
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* George Oikonomou - <oikonomou@users.sourceforge.net>
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*/
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#include "cc253x.h"
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#include "sfr-bits.h"
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#include "dev/cc2530-rf.h"
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Generates a new random number using the cc253x RNG.
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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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/* Clock the RNG LSFR once */
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ADCCON1 |= ADCCON1_RCTRL0;
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return (RNDL | (RNDH << 8));
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}
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/*---------------------------------------------------------------------------*/
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/**
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* \brief Seed the cc253x random number generator.
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* \param seed Ignored. It's here because the function prototype is in core.
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*
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* We form a seed for the RNG by sampling IF_ADC as
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* discussed in the user guide.
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* Seeding with this method should not be done during
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* normal radio operation. Thus, use this function before
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* initialising the network.
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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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int i;
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/* Make sure the RNG is on */
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ADCCON1 &= ~(ADCCON1_RCTRL1 | ADCCON1_RCTRL0);
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/* Infinite RX */
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FRMCTRL0 = FRMCTRL0_RX_MODE1;
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/* Turn RF on */
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CC2530_CSP_ISRXON();
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/* Wait until (user guide sec. 23.12, p 239) "the chip has been in RX long
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* enough for the transients to have died out. A convenient way to do this is
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* to wait for the RSSI-valid signal to go high." */
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while(!(RSSISTAT & RSSISTAT_RSSI_VALID));
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/*
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* Form the seed by concatenating bits from IF_ADC in the RF receive path.
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* Keep sampling until we have read at least 16 bits AND the seed is valid
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*
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* Invalid seeds are 0x0000 and 0x8003 - User Guide (sec. 14.2.2 p. 146):
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* "Note that a seed value of 0x0000 or 0x8003 always leads to an unchanged
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* value in the LFSR after clocking, as no values are pushed in via in_bit
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* (see Figure 14-1); hence, neither of these seed values should not be used
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* for random-number generation."
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*/
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i = 0;
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while(i < 16 || (seed == 0x0000 || seed == 0x8003)) {
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seed = (seed << 1) | (RFRND & RFRND_IRND);
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seed <<= 1;
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i++;
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}
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/* High byte first */
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RNDL = seed >> 8;
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RNDL = seed & 0xFF;
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/* RF Off. NETSTACK_RADIO.init() will sort out normal RF operation */
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CC2530_CSP_ISRFOFF();
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}
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