neorv32/sw/example/demo_crc/main.c

// ================================================================================ //
// The NEORV32 RISC-V Processor - https://github.com/stnolting/neorv32              //
// Copyright (c) NEORV32 contributors.                                              //
// Copyright (c) 2020 - 2025 Stephan Nolting. All rights reserved.                  //
// Licensed under the BSD-3-Clause license, see LICENSE for details.                //
// SPDX-License-Identifier: BSD-3-Clause                                            //
// ================================================================================ //


/**********************************************************************//**
 * @file demo_crc/main.c
 * @brief CRC demo program.
 **************************************************************************/

#include <neorv32.h>


/**********************************************************************//**
 * @name User configuration
 **************************************************************************/
/**@{*/
/** UART BAUD rate */
#define BAUD_RATE 19200
/**@}*/

// CRC test array
const uint8_t test_string[] = {0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x00};


/**********************************************************************//**
 * Simple demo program to showcase the NEORV32 CRC unit.
 *
 * @note This program requires UART0 and the CRC unit to be synthesized.
 * The DMA controller is optional.
 *
 * @return Irrelevant.
 **************************************************************************/
int main() {

  // setup NEORV32 runtime environment
  neorv32_rte_setup();

  // setup UART at default baud rate, no interrupts
  neorv32_uart0_setup(BAUD_RATE, 0);

  // intro
  neorv32_uart0_printf("\n<<< CRC Unit Demo Program >>>\n\n");

  // check if CRC unit is implemented at all
  if (neorv32_crc_available() == 0) {
    neorv32_uart0_printf("ERROR! CRC unit not implemented!\n");
    return 1;
  }

  uint32_t result, polynomial, reference, seed;
  neorv32_uart0_printf("Test string: '%s'\n", test_string);

  // CRC8 example
  polynomial = 0x07;
  reference  = 0x5b; // generated by http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
  seed       = 0x00;
  neorv32_crc_setup(CRC_MODE8, polynomial, seed);
  result = neorv32_crc_block((uint8_t*)test_string, sizeof(test_string)) & 0xff;
  neorv32_uart0_printf("\n[CRC8]\n");
  neorv32_uart0_printf("Polynomial = 0x%x\n", polynomial);
  neorv32_uart0_printf("Seed       = 0x%x\n", seed);
  neorv32_uart0_printf("Result     = 0x%x ", result);
  if (result == reference) {
    neorv32_uart0_printf("[OK]\n");
  }
  else {
    neorv32_uart0_printf("[FAILED]\n");
  }

  // CRC16 example
  polynomial = 0x1021;
  reference  = 0x96B9; // generated by http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
  seed       = 0x0000;
  neorv32_crc_setup(CRC_MODE16, polynomial, seed);
  result = neorv32_crc_block((uint8_t*)test_string, sizeof(test_string)) & 0xffff;
  neorv32_uart0_printf("\n[CRC16]\n");
  neorv32_uart0_printf("Polynomial = 0x%x\n", polynomial);
  neorv32_uart0_printf("Seed       = 0x%x\n", seed);
  neorv32_uart0_printf("Result     = 0x%x ", result);
  if (result == reference) {
    neorv32_uart0_printf("[OK]\n");
  }
  else {
    neorv32_uart0_printf("[FAILED]\n");
  }

  // CRC32 example
  polynomial = 0x04C11DB7;
  reference  = 0xF58D7B78; // generated by http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
  seed       = 0xFFFFFFFF;
  neorv32_crc_setup(CRC_MODE32, polynomial, seed);
  result = neorv32_crc_block((uint8_t*)test_string, sizeof(test_string)) & 0xffffffff;
  neorv32_uart0_printf("\n[CRC32]\n");
  neorv32_uart0_printf("Polynomial = 0x%x\n", polynomial);
  neorv32_uart0_printf("Seed       = 0x%x\n", seed);
  neorv32_uart0_printf("Result     = 0x%x ", result);
  if (result == reference) {
    neorv32_uart0_printf("[OK]\n");
  }
  else {
    neorv32_uart0_printf("[FAILED]\n");
  }

  // CRC8 example using the DMA
  if (neorv32_dma_available() != 0) {

    polynomial = 0x07;
    reference  = 0x5b; // generated by http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
    seed       = 0x00;
    neorv32_crc_setup(CRC_MODE8, polynomial, seed);

    neorv32_uart0_printf("\n[CRC8] using DMA\n");
    neorv32_uart0_printf("Polynomial = 0x%x\n", polynomial);
    neorv32_uart0_printf("Seed       = 0x%x\n", seed);

    neorv32_dma_enable();

    // configure DMA descriptor
    neorv32_dma_desc_t dma_desc;
    dma_desc.src = (uint32_t)(&test_string[0]);    // source array base address (data = 0xff)
    dma_desc.dst = (uint32_t)(&NEORV32_CRC->DATA); // destination address = CRC data register (32-bit!)
    dma_desc.num = sizeof(test_string);            // number of elements to transfer
    dma_desc.cmd = DMA_CMD_B2UW     |              // read source in byte quantities, write destination in WORD quantities
                   DMA_CMD_SRC_INC  |              // auto-increment source address
                   DMA_CMD_DST_CONST;              // constant destination address

    // trigger DMA transfer
    neorv32_dma_transfer(&dma_desc);

    // wait for transfer to complete using polling
    neorv32_uart0_printf("Waiting for DMA... ");
    int rc;
    while (1) {
      rc = neorv32_dma_status();
      if (rc == DMA_STATUS_DONE) {
        neorv32_uart0_printf("Transfer done.\n");
        break;
      }
      else if ((rc == DMA_STATUS_ERR_RD) || (rc == DMA_STATUS_ERR_WR)) {
        neorv32_uart0_printf("Transfer failed!\n");
        break;
      }
    }

    // check DMA status
    rc = neorv32_dma_status();
    if ((rc == DMA_STATUS_ERR_RD) || (rc == DMA_STATUS_ERR_WR)) {
      neorv32_uart0_printf("Transfer failed!\n");
    }

    result = neorv32_crc_get() & 0xff;
    neorv32_uart0_printf("Result     = 0x%x ", result);
    if (result == reference) {
      neorv32_uart0_printf("[OK]\n");
    }
    else {
      neorv32_uart0_printf("[FAILED]\n");
    }

  }

  neorv32_uart0_printf("\nProgram completed.\n");
  return 0;
}