watchrobot/modules/ChibiOS/os/various/wolfssl_bindings/hwrng.c

/*
    ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/
/*
 * **** This file incorporates work covered by the following copyright and ****
 * **** permission notice:                                                 ****
 *
 * Copyright (C) 2006-2017 wolfSSL Inc.
 *
 * This file is part of wolfSSL.
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
 *
 */
#include <ch.h>
#include <stdint.h>
#include "wolfssl_chibios.h"
#include "user_settings.h"

unsigned int chibios_rand_generate(void)
{
  static unsigned int last_value=0;
  static unsigned int new_value=0;
  unsigned int error_bits = 0;
  error_bits = RNG_SR_SEIS | RNG_SR_CEIS;
  while (new_value==last_value) {
    /* Check for error flags and if data is ready. */
    if ( ((RNG->SR & error_bits) == 0) && ( (RNG->SR & RNG_SR_DRDY) == 1 ) )
      new_value=RNG->DR;
  }
  last_value=new_value;
  return new_value;
}

int custom_rand_generate_block(unsigned char* output, unsigned int sz)
{
    uint32_t i = 0;

    while (i < sz)
    {
        /* If not aligned or there is odd/remainder */
        if( (i + sizeof(CUSTOM_RAND_TYPE)) > sz ||
            ((uint32_t)&output[i] % sizeof(CUSTOM_RAND_TYPE)) != 0
        ) {
            /* Single byte at a time */
            output[i++] = (unsigned char)chibios_rand_generate();
        }
        else {
            /* Use native 8, 16, 32 or 64 copy instruction */
            *((CUSTOM_RAND_TYPE*)&output[i]) = chibios_rand_generate();
            i += sizeof(CUSTOM_RAND_TYPE);
        }
    }
    return 0;
}