//
// Flash: Nonvolatile storage for settings / etc
//

#include "stm32f3xx_hal.h"
#include "flash.h"
#include "config.h"

// Takes up 1 page (1k size)
static __attribute__((__section__(".eeprom"))) uint16_t eeprom_emulation[512];
settings_t settings;


// Initialize flash and restore settings
void flash_init(void)
{
	flash_restoresettings();
}


// Save settings to flash memory
void flash_savesettings(void)
{
	// Unlock flash memory
	HAL_FLASH_Unlock();

	// Initialize eraser to erase one page of flash
	FLASH_EraseInitTypeDef eraser =
	{
			.TypeErase = TYPEERASE_PAGES,
			.PageAddress = eeprom_emulation,
			.NbPages = 1,
	};
	uint32_t errvar = 0;

	// Erase flash page
	HAL_FLASHEx_Erase(&eraser, &errvar);

	// Write new flash data
	uint16_t writectr;
	for(writectr = 0; writectr < 128; writectr++)// 128 bytes data
	{
		HAL_FLASH_Program(TYPEPROGRAM_HALFWORD, eeprom_emulation+writectr,settings.data[writectr]);
	}

	// Write magic value to flash
	HAL_FLASH_Program(TYPEPROGRAM_HALFWORD, eeprom_emulation+FLASH_MAGIC_LOC,FLASH_MAGIC_VALUE);

	// Lock flash memory
	HAL_FLASH_Lock();
	HAL_Delay(2);
}


// Restore configuration from flash memory, if any was previously saved
void flash_restoresettings(void)
{
	// Check for magic flash value
	if(eeprom_emulation[FLASH_MAGIC_LOC] == FLASH_MAGIC_VALUE)
	{
		// Read page of flash into settings structure
		uint16_t readctr = 0;
		for(readctr = 0; readctr < 128; readctr++)
		{
			settings.data[readctr] = eeprom_emulation[readctr];
		}
	}
	// No data in flash! Set defaults here
	else
	{
		settings.values.can_id = 22;
	}
}


// Accessor to retrieve settings structure
inline settings_t* flash_getsettings(void)
{
	return &settings;
}