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// #################################################################################################
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// # < neo430_trng.c - True random number generator helper functions > #
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// # ********************************************************************************************* #
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// # BSD 3-Clause License #
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// # #
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// # Copyright (c) 2020, Stephan Nolting. All rights reserved. #
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// # #
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// # Redistribution and use in source and binary forms, with or without modification, are #
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// # permitted provided that the following conditions are met: #
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// # #
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// # 1. Redistributions of source code must retain the above copyright notice, this list of #
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// # conditions and the following disclaimer. #
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// # #
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// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
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// # conditions and the following disclaimer in the documentation and/or other materials #
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// # provided with the distribution. #
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// # #
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// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
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// # endorse or promote products derived from this software without specific prior written #
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// # permission. #
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// # #
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// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
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// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
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// # MERCHANTABILITY AND FITNESS 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, INCIDENTAL, SPECIAL, #
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// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
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// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
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// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
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// # NEGLIGENCE OR OTHERWISE) 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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// # The NEO430 Processor - https://github.com/stnolting/neo430 #
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// #################################################################################################
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#include "neo430.h"
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#include "neo430_trng.h"
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/* ------------------------------------------------------------
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* INFO Enable TRNG
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* ------------------------------------------------------------ */
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void neo430_trng_enable(uint16_t tap_mask) {
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TRNG_CT = 0; // reset
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asm volatile("nop");
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asm volatile("nop");
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asm volatile("nop");
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TRNG_CT = (1<<TRNG_CT_EN) | tap_mask;
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asm volatile("nop");
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asm volatile("nop");
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asm volatile("nop");
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}
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/* ------------------------------------------------------------
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* INFO Disable TRNG
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* ------------------------------------------------------------ */
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void neo430_trng_disable(void) {
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TRNG_CT = 0;
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}
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/* ------------------------------------------------------------
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* INFO Get TRNG data and status information
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* PARAM byte-pointer to store random data
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* RETURN is 0 when data is VALID
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* ------------------------------------------------------------ */
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uint16_t neo430_trng_get(uint8_t *data) {
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uint16_t trng_ct = TRNG_CT;
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*data = (uint8_t)trng_ct; // actual TRNG data
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if (trng_ct & (1<<TRNG_CT_VALID)) // output data valid?
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return 0;
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else
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return 1;
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}
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