SSUBoot.ino

/*
  Copyright (c) 2020 Arduino LLC.  All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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 Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

/**************************************************************************************
   INCLUDE
 **************************************************************************************/

#include <FlashStorage.h>
#include <MKRGSM.h>

#include "lzss.h"

/**************************************************************************************
   DEFINE
 **************************************************************************************/

#define SSU_START    0x2000
#define SSU_SIZE     0x8000

#define SKETCH_START (uint32_t*)(SSU_START + SSU_SIZE)

/**************************************************************************************
   GLOBAL CONSTANTS
 **************************************************************************************/

       const char * UPDATE_FILE_NAME      = "UPDATE.BIN";
       const char * UPDATE_FILE_NAME_LZSS = "UPDATE.BIN.LZSS";
static const char * CHECK_FILE_NAME       = "UPDATE.OK";

/**************************************************************************************
   GLOBAL VARIABLES
 **************************************************************************************/

FlashClass mcu_flash;
GSMFileUtils fileUtils;

/**************************************************************************************
   FUNCTION DECLARATION
 **************************************************************************************/

extern "C" void __libc_init_array(void);

/**************************************************************************************
   MAIN
 **************************************************************************************/

int main()
{
  init();

  __libc_init_array();

  delay(1);

  constexpr size_t blockSize = 512;

  fileUtils.begin();

  bool update_success = false;

  // Try to update only if update file
  // has been download successfully.
  if (fileUtils.listFile(CHECK_FILE_NAME) > 0)
  {
    /* This is for LZSS compressed binaries. */
    if (fileUtils.listFile(UPDATE_FILE_NAME_LZSS) > 0)
    {
      /* Erase the complete flash starting from the SSU forward
       * because we've got no possibility of knowing how large
       * the decompressed binary will finally be.
       */
      mcu_flash.erase((void*)SKETCH_START, 0x40000 - (uint32_t)SKETCH_START);
      /* Initialize the lzss module with the data which
       * it requires.
       */
      lzss_init((uint32_t)SKETCH_START);
      /* During the process of decoding UPDATE.BIN.LZSS
       * is decompressed and stored as UPDATE.BIN.
       */
      lzss_decode();
      /* Write the data remaining in the write buffer to
       * the file.
       */
      lzss_flush();
      /* Signal a successul update. */
      update_success = true;
    }
    /* This is for uncompressed binaries. */
    else if (fileUtils.listFile(UPDATE_FILE_NAME) > 0)
    {
      uint32_t size = fileUtils.listFile(UPDATE_FILE_NAME);
      size_t cycles = (size / blockSize) + 1;

      if (size > SSU_SIZE) {
        size -= SSU_SIZE;

        /* Erase the MCU flash */
        uint32_t flash_address = (uint32_t)SKETCH_START;
        mcu_flash.erase((void*)flash_address, size);

        for (auto i = 0; i < cycles; i++) {
          uint8_t block[blockSize] { 0 };
          digitalWrite(LED_BUILTIN, LOW);
          uint32_t read = fileUtils.readBlock(UPDATE_FILE_NAME, (i * blockSize) + SSU_SIZE, blockSize, block);
          digitalWrite(LED_BUILTIN, HIGH);
          mcu_flash.write((void*)flash_address, block, read);
          flash_address += read;
        }
        update_success = true;
      }
    }
    /* Clean up in case of success */
    if (update_success) {
      fileUtils.deleteFile(UPDATE_FILE_NAME);
      fileUtils.deleteFile(UPDATE_FILE_NAME_LZSS);
      fileUtils.deleteFile(CHECK_FILE_NAME);
    }
  }
  /* Jump to the sketch */
  __set_MSP(*SKETCH_START);

  /* Reset vector table address */
  SCB->VTOR = ((uint32_t)(SKETCH_START) & SCB_VTOR_TBLOFF_Msk);

  /* Address of Reset_Handler is written by the linker at the beginning of the .text section (see linker script) */
  uint32_t resetHandlerAddress = (uint32_t) * (SKETCH_START + 1);
  /* Jump to reset handler */
  asm("bx %0"::"r"(resetHandlerAddress));
}