/** library to program EEPROM using block programming
 *  @file
 *  @author King Kévin <kingkevin@cuvoodoo.info>
 *  @copyright SPDX-License-Identifier: GPL-3.0-or-later
 *  @date 2021
 *  @warning functions need to be put in and run from RAM (because block programming is used)
 */

// RAM code-putting from https://lujji.github.io/blog/executing-code-from-ram-on-stm8/

/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdbool.h> // boolean types

#include "stm8s.h" // STM8S definitions
#include "eeprom_blockprog.h" // own definitions

// start address of EEPROM
#define EEPROM_ADDR 0x4000
// block size from low-density devices (including STM8S103)
#define DATA_BLOCK_SIZE 64U

#pragma codeseg RAM_SEG
bool eeprom_blockprog(const uint8_t* data, uint16_t length)
{
	if (0 == length) {
		return true; // nothing to do
	}
	if (!data) {
		return false; // data missing
	}
	if (0 != (length % DATA_BLOCK_SIZE)) {
		return false; // we can only program whole blocks
	}

	// disable DATA (e.g. EEPROM) write protection
	// don't check if it is locked this it does not save that much time and uses memory)
	FLASH_DUKR = FLASH_DUKR_KEY1;
	FLASH_DUKR = FLASH_DUKR_KEY2;
// don't verify if unlock succeeded to save memory
//	if (!(FLASH_IAPSR & FLASH_IAPSR_DUL)) { // un-protecting failed
//		return false;
//	}


	// program data
	uint8_t* eeprom = (uint8_t*)(EEPROM_ADDR);
	while (length) {
		// enable standard block programming
		FLASH_CR2 |= FLASH_CR2_PRG;
		FLASH_NCR2 &= ~FLASH_NCR2_NPRG;
		// program block
		for (uint8_t i = 0; i < DATA_BLOCK_SIZE; i++) {
			*(eeprom++) = *(data++);
		}
		length -= DATA_BLOCK_SIZE;
		// wait until program completed
		while (FLASH_CR2 & FLASH_CR2_PRG);
		// check if programming failed
		// we don't check for WR_PG_DIS (while checking EOP) because EEPROM isn't (and can't be) write protected
		if (!(FLASH_IAPSR & FLASH_IAPSR_EOP)) {
			FLASH_IAPSR &= ~FLASH_IAPSR_DUL; // re-enable write protection
			return false;
		}
	}

	FLASH_IAPSR &= ~FLASH_IAPSR_DUL; // re-enable write protection
	return true;
}