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66 mjames 1 
/*
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 * nvram.c
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 *
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 *  Created on: 4 Jun 2017
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 *      Author: Mike
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 */
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/* Includes ------------------------------------------------------------------*/
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#include "stm32l1xx_hal.h"
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#include "nvram.h"
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// NVRAM hardware erases to all 0x
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nvram_info_t const HARDWARE_ERASED = {.u32 = 0UL};
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// Marked as erased change to all 1
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nvram_info_t const MARKED_ERASED = {.u32 = ~0UL};
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// marked as unusable  change pattern to something in between
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nvram_info_t const MARKED_UNUSABLE = {.u32 = 0x555555FFUL};
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nvram_info_t NVRAM_Base[NVRAM_WORDS] __attribute__((section(".NVRAM_Data"))); // set by linker
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static void
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WriteNVRAM(int offset, nvram_info_t data)
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{
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  HAL_FLASHEx_DATAEEPROM_Unlock();
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  HAL_FLASHEx_DATAEEPROM_Program(FLASH_TYPEPROGRAMDATA_WORD, (uint32_t)(&NVRAM_Base[offset]), data.u32);
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  HAL_FLASHEx_DATAEEPROM_Lock();
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}
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static void
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EraseNVRAM(int offset)
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{
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  HAL_FLASHEx_DATAEEPROM_Unlock();
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  HAL_FLASHEx_DATAEEPROM_Erase(FLASH_TYPEERASEDATA_WORD, (uint32_t)(&NVRAM_Base[offset]));
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  HAL_FLASHEx_DATAEEPROM_Lock();
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}
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void write_nvram_data(nvram_info_t data)
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{
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#if defined SEMIHOSTING
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  printf("write\n");
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#endif
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  int base = 0;
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  /* search blank */
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  for (int ptr = 0; ptr < NVRAM_WORDS; ptr++)
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  {
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    // erase the entry just found
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    if (NVRAM_Base[ptr].data.tag == data.data.tag)
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    {
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      // erase previous data, delete any entries that have a matching tag
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#if defined SEMIHOSTING
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      printf("marked erased %d\n", ptr);
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#endif
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      WriteNVRAM(ptr, MARKED_ERASED);
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      base = ptr;
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    }
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  }
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  // search forward for next erased or empty element, use it
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  for (int offset = 1; offset < NVRAM_WORDS + 1; offset++)
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  {
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    int index = (base + offset) % NVRAM_WORDS;
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    if (NVRAM_Base[index].u32 == MARKED_ERASED.u32 || NVRAM_Base[index].u32 == HARDWARE_ERASED.u32)
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    {
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      if (NVRAM_Base[index].u32 != HARDWARE_ERASED.u32)
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      {
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   #if defined SEMIHOSTING
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       printf("erase %d\n", index);
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#endif
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        EraseNVRAM(index);
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      }
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        #if defined SEMIHOSTING
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printf("write %d=%d\n", index, data.data.pos);
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#endif
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      WriteNVRAM(index, data);
66 mjames 80 
      // now check to see if it actually went
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      if (NVRAM_Base[index].u32 != data.u32)
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      {
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          #if defined SEMIHOSTING
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        printf("unusable %d\n", index);
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#endif
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        WriteNVRAM(index, MARKED_UNUSABLE); // mark as neither unused or used
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        continue;
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      }
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      return;
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    }
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  }
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}
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nvram_info_t *find_nvram_data(uint8_t searchTag)
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{  
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  #if defined SEMIHOSTING
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  printf("find\n");
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#endif
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  for (int ptr = 0; ptr < NVRAM_WORDS; ptr++)
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  {
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    if (NVRAM_Base[ptr].data.tag == searchTag)
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    {
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        #if defined SEMIHOSTING
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      printf("found %d=%d\n", ptr, NVRAM_Base[ptr].data.pos);
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#endif
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      return &NVRAM_Base[ptr];
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    }
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  }
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  return NULL;
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}
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void erase_nvram()
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{
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    #if defined SEMIHOSTING
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  printf("erase all\n");
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#endif
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  for (int ptr = 0; ptr < NVRAM_WORDS; ptr++)
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    EraseNVRAM(ptr);
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}