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[/] [neorv32/] [trunk/] [sw/] [lib/] [source/] [neorv32_trng.c] - Rev 25
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// ################################################################################################# // # << NEORV32: neorv32_trng.c - True Random Number Generator (TRNG) HW Driver >> # // # ********************************************************************************************* # // # BSD 3-Clause License # // # # // # Copyright (c) 2020, Stephan Nolting. 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. # // # ********************************************************************************************* # // # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting # // ################################################################################################# /**********************************************************************//** * @file neorv32_trng.c * @author Stephan Nolting * @brief True Random Number Generator (TRNG) HW driver source file. * * @note These functions should only be used if the TRNG unit was synthesized (IO_TRNG_USE = true). **************************************************************************/ #include "neorv32.h" #include "neorv32_trng.h" /**********************************************************************//** * Check if TRNG unit was synthesized. * * @return 0 if TRNG was not synthesized, 1 if TRNG is available. **************************************************************************/ int neorv32_trng_available(void) { if (SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_IO_TRNG)) { return 1; } else { return 0; } } /**********************************************************************//** * Enable true random number generator. The TRNG control register bits are listed in #NEORV32_TRNG_CT_enum. **************************************************************************/ void neorv32_trng_enable(void) { int i; TRNG_CT = 0; // reset for (i=0; i<1000; i++) { asm volatile ("nop"); } TRNG_CT = 1 << TRNG_CT_EN; // activate for (i=0; i<1000; i++) { asm volatile ("nop"); } } /**********************************************************************//** * Disable true random number generator. **************************************************************************/ void neorv32_trng_disable(void) { TRNG_CT &= ~((uint32_t)(1 << TRNG_CT_EN)); } /**********************************************************************//** * Get random data from TRNG. * * @note The TRNG is automatically reset if a stuck-at-one/stuck-at-zero error is detected. * * @param[in,out] data uint8_t pointer for storing random data word * @return Data is valid when 0, stuck-at-zero error when 1, stuck-at-one error when 2, data not (yet) valid when 3 **************************************************************************/ int neorv32_trng_get(uint8_t *data) { uint32_t trng_ct_reg = TRNG_CT; if (trng_ct_reg & (1<<TRNG_CT_ERROR_0)) { // stuck at zero error neorv32_trng_enable(); // reset TRNG return 1; } if (trng_ct_reg & (1<<TRNG_CT_ERROR_1)) { // stuck at one error neorv32_trng_enable(); // reset TRNG return 2; } if ((trng_ct_reg & (1<<TRNG_CT_VALID)) == 0) { // output data valid (yet)? return 3; } *data = (uint8_t)(trng_ct_reg >> TRNG_CT_DATA_LSB); return 0; // valid data }
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