Subversion Repositories neo430

// #################################################################################################
// #  < neo430_trng.c - True random number generator helper functions >                            #
// # ********************************************************************************************* #
// # BSD 3-Clause License                                                                          #
// #                                                                                               #
// # Copyright (c) 2020, Stephan Nolting. All rights reserved.                                     #
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// # permitted provided that the following conditions are met:                                     #
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// #    permission.                                                                                #
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// # ********************************************************************************************* #
// # The NEO430 Processor - https://github.com/stnolting/neo430                                    #
// #################################################################################################
 
#include "neo430.h"
#include "neo430_trng.h"
 
 
/* ------------------------------------------------------------
 * INFO Enable TRNG
 * ------------------------------------------------------------ */
void neo430_trng_enable(uint16_t tap_mask) {
 
  TRNG_CT = 0; // reset
 
  asm volatile("nop");
  asm volatile("nop");
  asm volatile("nop");
 
  TRNG_CT = (1<<TRNG_CT_EN) | tap_mask;
 
  asm volatile("nop");
  asm volatile("nop");
  asm volatile("nop");
}
 
 
/* ------------------------------------------------------------
 * INFO Disable TRNG
 * ------------------------------------------------------------ */
void neo430_trng_disable(void) {
 
  TRNG_CT = 0;
}
 
 
/* ------------------------------------------------------------
 * INFO Get TRNG data and status information
 * PARAM byte-pointer to store random data
 * RETURN is 0 when data is VALID
 * ------------------------------------------------------------ */
uint16_t neo430_trng_get(uint8_t *data) {
 
  uint16_t trng_ct = TRNG_CT;
  *data = (uint8_t)trng_ct; // actual TRNG data
  if (trng_ct & (1<<TRNG_CT_VALID)) // output data valid?
    return 0;
  else
    return 1;
}