Subversion Repositories neorv32

// #################################################################################################
// # << NEORV32 - TRNG Demo Program >>                                                             #
// # ********************************************************************************************* #
// # BSD 3-Clause License                                                                          #
// #                                                                                               #
// # Copyright (c) 2021, 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.                                                                                #
// #                                                                                               #
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// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF               #
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// # ********************************************************************************************* #
// # The NEORV32 Processor - https://github.com/stnolting/neorv32              (c) Stephan Nolting #
// #################################################################################################
 
 
/**********************************************************************//**
 * @file demo_trng/main.c
 * @author Stephan Nolting
 * @brief True random number generator demo program.
 **************************************************************************/
 
#include <neorv32.h>
 
 
/**********************************************************************//**
 * @name User configuration
 **************************************************************************/
/**@{*/
/** UART BAUD rate */
#define BAUD_RATE 19200
/**@}*/
 
 
// prototypes
void print_random_data(void);
void generate_histogram(void);
 
 
/**********************************************************************//**
 * Simple true random number test/demo program.
 *
 * @note This program requires the UART and the TRNG to be synthesized.
 *
 * @return 0 if execution was successful
 **************************************************************************/
int main(void) {
 
  // check if UART unit is implemented at all
  if (neorv32_uart0_available() == 0) {
    return 1;
  }
 
  // capture all exceptions and give debug info via UART
  // this is not required, but keeps us safe
  neorv32_rte_setup();
 
 
  // init UART at default baud rate, no parity bits, ho hw flow control
  neorv32_uart0_setup(BAUD_RATE, PARITY_NONE, FLOW_CONTROL_NONE);
 
  // check available hardware extensions and compare with compiler flags
  neorv32_rte_check_isa(0); // silent = 0 -> show message if isa mismatch
 
  // intro
  neorv32_uart0_printf("\n<<< NEORV32 TRNG Demo >>>\n");
 
  // check if TRNG unit is implemented at all
  if (neorv32_trng_available() == 0) {
    neorv32_uart0_printf("No TRNG implemented.");
    return 1;
  }
 
  // enable TRNG
  neorv32_trng_enable();
  neorv32_cpu_delay_ms(100); // TRNG "warm up"
 
  while(1) {
 
    // main menu
    neorv32_uart0_printf("\nCommands:\n"
                         " n: Print 8-bit random numbers (abort by pressing any key)\n"
                         " h: Generate histogram and analyze data\n");
 
    neorv32_uart0_printf("CMD:> ");
    char cmd = neorv32_uart0_getc();
    neorv32_uart0_putc(cmd); // echo
    neorv32_uart0_printf("\n");
 
    if (cmd == 'n') {
      print_random_data();
    }
    else if (cmd == 'h') {
      generate_histogram();
    }
    else {
      neorv32_uart0_printf("Invalid command.\n");
    }
  }
 
  return 0;
}
 
 
/**********************************************************************//**
 * Print random numbers until a key is pressed.
 **************************************************************************/
void print_random_data(void) {
 
  uint32_t num_samples = 0;
  int err = 0;
  uint8_t trng_data;
 
  while(1) {
    err = neorv32_trng_get(&trng_data);
    if (err) {
      neorv32_uart0_printf("\nTRNG error!\n");
      break;
    }
    neorv32_uart0_printf("%u ", (uint32_t)(trng_data));
    num_samples++;
    if (neorv32_uart0_char_received()) { // abort when key pressed
      break;
    }
  }
  neorv32_uart0_printf("\nPrinted samples: %u\n", num_samples);
}
 
 
/**********************************************************************//**
 * Generate and print histogram. Samples random data until a key is pressed.
 **************************************************************************/
void generate_histogram(void) {
 
  uint32_t hist[256];
  uint32_t i;
  uint32_t cnt = 0;
  uint8_t trng_data;
  uint64_t average = 0;
 
  neorv32_uart0_printf("Press any key to start.\n");
 
  while(neorv32_uart0_char_received() == 0);
  neorv32_uart0_printf("Sampling... Press any key to stop.\n");
 
  // clear histogram
  for (i=0; i<256; i++) {
    hist[i] = 0;
  }
 
 
  // sample random data
  while(1) {
 
    // get raw TRNG data
    if (neorv32_trng_get(&trng_data)) {
      continue;
    }
 
    // add to histogram
    hist[trng_data & 0xff]++;
    cnt++;
 
    // average
    average += (uint64_t)trng_data;
 
    // abort conditions
    if ((neorv32_uart0_char_received()) || // abort when key pressed
        (cnt & 0x80000000UL)) { // to prevent overflow
      break;
    }
  }
 
  average = average / cnt;
 
 
  // deviation (histogram samples)
  uint32_t avg_occurence = cnt / 256;
  int32_t tmp_int;
  int32_t dev_int;
  int32_t dev_int_max = 0x80000000UL; uint32_t bin_max = 0;
  int32_t dev_int_min = 0x7fffffffUL; uint32_t bin_min = 0;
  int32_t dev_int_avg = 0;
  for (i=0; i<256; i++) {
    tmp_int = (int32_t)hist[i];
    dev_int = tmp_int - avg_occurence;
 
    dev_int_avg += (uint64_t)dev_int;
 
    if (dev_int < dev_int_min) {
      dev_int_min = dev_int;
      bin_min = i;
    }
    if (dev_int > dev_int_max) {
      dev_int_max = dev_int;
      bin_max = i;
    }
  }
 
  dev_int_avg = dev_int_avg / 256;
 
  // print histogram
  neorv32_uart0_printf("Histogram [random data value] : [# occurrences]\n");
  for (i=0; i<256; i++) {
    neorv32_uart0_printf("%u: %u\n", (uint32_t)i, hist[i]);
  }
  neorv32_uart0_printf("\n");
 
 
  // print results
  neorv32_uart0_printf("Analysis results (integer only)\n\n");
  neorv32_uart0_printf("Number of samples: %u\n", cnt);
  neorv32_uart0_printf("Arithmetic mean:   %u\n", (uint32_t)average);
  neorv32_uart0_printf("\nArithmetic deviation\n");
  neorv32_uart0_printf("Avg. occurrence: %u\n", avg_occurence);
  neorv32_uart0_printf("Avg. deviation:  %i\n", dev_int_avg);
  neorv32_uart0_printf("Minimum:         %i (histogram bin %u)\n", dev_int_min, bin_min);
  neorv32_uart0_printf("Maximum:         %i (histogram bin %u)\n", dev_int_max, bin_max);
}