/*
 * nvram.c
 *
 *  Created on: 4 Jun 2017
 *      Author: Mike
 */

/* Includes ------------------------------------------------------------------*/
#include "stm32l1xx_hal.h"

#include "nvram.h"

nvram_info_t NVRAM_Base[NVRAM_WORDS] __attribute__((section(".NVRAM_Data"))); // set by linker 

static void
WriteNVRAM(nvram_info_t *Address, nvram_info_t data)
{
  HAL_FLASHEx_DATAEEPROM_Unlock();
  HAL_FLASHEx_DATAEEPROM_Program(FLASH_TYPEPROGRAMDATA_WORD, (uint32_t)Address, data.u32);
  HAL_FLASHEx_DATAEEPROM_Lock();
}

static void
EraseNVRAM(nvram_info_t *Address)
{
  HAL_FLASHEx_DATAEEPROM_Unlock();
  HAL_FLASHEx_DATAEEPROM_Erase(FLASH_TYPEERASEDATA_WORD, (uint32_t)Address);
  HAL_FLASHEx_DATAEEPROM_Lock();
}

void write_nvram_data(nvram_info_t data)
{

  /* search blank */
  for (int ptr = 0; ptr < NVRAM_WORDS; ptr++)
  {

    // erase the entry just found
    if (NVRAM_Base[ptr].data.tag == data.data.tag)
    {
      nvram_info_t dat;
      dat.u32 = ~0;
      // erase previous data, leave as 0xFF
      WriteNVRAM(&NVRAM_Base[ptr], dat);
      // search forward for next erased or empty element, use it 
      for (int offset = 1; offset < NVRAM_WORDS+1; offset++)
      {
        int index = (ptr + offset) % NVRAM_WORDS;
        if (NVRAM_Base[index].u32 == ~0 || NVRAM_Base[index].u32 == 0)
        {
          if (NVRAM_Base[index].u32 != 0)
            EraseNVRAM(&NVRAM_Base[ptr]);
          WriteNVRAM(&NVRAM_Base[ptr], data);
          return;
        }
      }
    }
  }
}

nvram_info_t *find_nvram_data(uint8_t searchTag)
{
  for (int ptr = 0; ptr < NVRAM_WORDS; ptr++)
  {
    if (NVRAM_Base[ptr].data.tag == searchTag)
      return &NVRAM_Base[ptr];
  }
  return NULL;
}