/* USER CODE BEGIN Header */
/**
 ******************************************************************************
 * @file           : main.c
 * @brief          : Main program body
 ******************************************************************************
 * @attention
 *
 * <h2><center>&copy; Copyright (c) 2021 STMicroelectronics.
 * All rights reserved.</center></h2>
 *
 * This software component is licensed by ST under Ultimate Liberty license
 * SLA0044, the "License"; You may not use this file except in compliance with
 * the License. You may obtain a copy of the License at:
 *                             www.st.com/SLA0044
 *
 ******************************************************************************
 */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "stm32f103xb.h"
#include "stm32f1xx_hal_dma.h"
#include "stm32f1xx_hal_flash.h"
#include "stm32f1xx_hal_flash_ex.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <errno.h>
#include <stdint.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
typedef void (*void_func_ptr)(void);
typedef enum {
	TARGET_NONE = 0,
	TARGET_ROM,
	TARGET_I2C
} UpdateTarget;
/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
#define STDIN_FILENO 0
#define STDOUT_FILENO 1
#define STDERR_FILENO 2

#define BOOTLOADER_RCC_CSR_ENTRY_MASK (RCC_CSR_WWDGRSTF | RCC_CSR_IWDGRSTF | RCC_CSR_SFTRSTF | RCC_CSR_PINRSTF)
#define BOOTLOADER_SIZE (16 * 1024)
#define USER_PROGRAM (FLASH_BASE + BOOTLOADER_SIZE)
/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/
UART_HandleTypeDef huart1;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART1_UART_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
static const uint32_t crc_table[0x100] = {
	0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9, 0x130476DC, 0x17C56B6B, 0x1A864DB2, 0x1E475005, 0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61, 0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD, 
	0x4C11DB70, 0x48D0C6C7, 0x4593E01E, 0x4152FDA9, 0x5F15ADAC, 0x5BD4B01B, 0x569796C2, 0x52568B75, 0x6A1936C8, 0x6ED82B7F, 0x639B0DA6, 0x675A1011, 0x791D4014, 0x7DDC5DA3, 0x709F7B7A, 0x745E66CD, 
	0x9823B6E0, 0x9CE2AB57, 0x91A18D8E, 0x95609039, 0x8B27C03C, 0x8FE6DD8B, 0x82A5FB52, 0x8664E6E5, 0xBE2B5B58, 0xBAEA46EF, 0xB7A96036, 0xB3687D81, 0xAD2F2D84, 0xA9EE3033, 0xA4AD16EA, 0xA06C0B5D, 
	0xD4326D90, 0xD0F37027, 0xDDB056FE, 0xD9714B49, 0xC7361B4C, 0xC3F706FB, 0xCEB42022, 0xCA753D95, 0xF23A8028, 0xF6FB9D9F, 0xFBB8BB46, 0xFF79A6F1, 0xE13EF6F4, 0xE5FFEB43, 0xE8BCCD9A, 0xEC7DD02D, 
	0x34867077, 0x30476DC0, 0x3D044B19, 0x39C556AE, 0x278206AB, 0x23431B1C, 0x2E003DC5, 0x2AC12072, 0x128E9DCF, 0x164F8078, 0x1B0CA6A1, 0x1FCDBB16, 0x018AEB13, 0x054BF6A4, 0x0808D07D, 0x0CC9CDCA, 
	0x7897AB07, 0x7C56B6B0, 0x71159069, 0x75D48DDE, 0x6B93DDDB, 0x6F52C06C, 0x6211E6B5, 0x66D0FB02, 0x5E9F46BF, 0x5A5E5B08, 0x571D7DD1, 0x53DC6066, 0x4D9B3063, 0x495A2DD4, 0x44190B0D, 0x40D816BA, 
	0xACA5C697, 0xA864DB20, 0xA527FDF9, 0xA1E6E04E, 0xBFA1B04B, 0xBB60ADFC, 0xB6238B25, 0xB2E29692, 0x8AAD2B2F, 0x8E6C3698, 0x832F1041, 0x87EE0DF6, 0x99A95DF3, 0x9D684044, 0x902B669D, 0x94EA7B2A, 
	0xE0B41DE7, 0xE4750050, 0xE9362689, 0xEDF73B3E, 0xF3B06B3B, 0xF771768C, 0xFA325055, 0xFEF34DE2, 0xC6BCF05F, 0xC27DEDE8, 0xCF3ECB31, 0xCBFFD686, 0xD5B88683, 0xD1799B34, 0xDC3ABDED, 0xD8FBA05A, 
	0x690CE0EE, 0x6DCDFD59, 0x608EDB80, 0x644FC637, 0x7A089632, 0x7EC98B85, 0x738AAD5C, 0x774BB0EB, 0x4F040D56, 0x4BC510E1, 0x46863638, 0x42472B8F, 0x5C007B8A, 0x58C1663D, 0x558240E4, 0x51435D53, 
	0x251D3B9E, 0x21DC2629, 0x2C9F00F0, 0x285E1D47, 0x36194D42, 0x32D850F5, 0x3F9B762C, 0x3B5A6B9B, 0x0315D626, 0x07D4CB91, 0x0A97ED48, 0x0E56F0FF, 0x1011A0FA, 0x14D0BD4D, 0x19939B94, 0x1D528623, 
	0xF12F560E, 0xF5EE4BB9, 0xF8AD6D60, 0xFC6C70D7, 0xE22B20D2, 0xE6EA3D65, 0xEBA91BBC, 0xEF68060B, 0xD727BBB6, 0xD3E6A601, 0xDEA580D8, 0xDA649D6F, 0xC423CD6A, 0xC0E2D0DD, 0xCDA1F604, 0xC960EBB3, 
	0xBD3E8D7E, 0xB9FF90C9, 0xB4BCB610, 0xB07DABA7, 0xAE3AFBA2, 0xAAFBE615, 0xA7B8C0CC, 0xA379DD7B, 0x9B3660C6, 0x9FF77D71, 0x92B45BA8, 0x9675461F, 0x8832161A, 0x8CF30BAD, 0x81B02D74, 0x857130C3, 
	0x5D8A9099, 0x594B8D2E, 0x5408ABF7, 0x50C9B640, 0x4E8EE645, 0x4A4FFBF2, 0x470CDD2B, 0x43CDC09C, 0x7B827D21, 0x7F436096, 0x7200464F, 0x76C15BF8, 0x68860BFD, 0x6C47164A, 0x61043093, 0x65C52D24, 
	0x119B4BE9, 0x155A565E, 0x18197087, 0x1CD86D30, 0x029F3D35, 0x065E2082, 0x0B1D065B, 0x0FDC1BEC, 0x3793A651, 0x3352BBE6, 0x3E119D3F, 0x3AD08088, 0x2497D08D, 0x2056CD3A, 0x2D15EBE3, 0x29D4F654, 
	0xC5A92679, 0xC1683BCE, 0xCC2B1D17, 0xC8EA00A0, 0xD6AD50A5, 0xD26C4D12, 0xDF2F6BCB, 0xDBEE767C, 0xE3A1CBC1, 0xE760D676, 0xEA23F0AF, 0xEEE2ED18, 0xF0A5BD1D, 0xF464A0AA, 0xF9278673, 0xFDE69BC4, 
	0x89B8FD09, 0x8D79E0BE, 0x803AC667, 0x84FBDBD0, 0x9ABC8BD5, 0x9E7D9662, 0x933EB0BB, 0x97FFAD0C, 0xAFB010B1, 0xAB710D06, 0xA6322BDF, 0xA2F33668, 0xBCB4666D, 0xB8757BDA, 0xB5365D03, 0xB1F740B4, 
};

uint32_t crc32(uint8_t* data, uint16_t length) {
	uint32_t crc = 0xFFFFFFFF;
	for(uint16_t i = 0; i < length; i++)
	{
		uint8_t top = (uint8_t)(crc >> 24);
		top ^= data[i];
		crc = (crc << 8) ^ crc_table[top];
	}
	return crc;
}

uint8_t should_start_user_program = 0;
void start_user_program() {
	// Deinit
	HAL_UART_DeInit(&huart1);
	HAL_GPIO_DeInit(GPIOC, GPIO_PIN_13);
	HAL_DeInit();

	// Setup
	void_func_ptr user_program = (void_func_ptr) *(volatile uint32_t*) (USER_PROGRAM + 0x04);
	SCB->VTOR = USER_PROGRAM;
	__set_MSP((*(volatile uint32_t*) USER_PROGRAM));

	// Call application
	user_program();

	while (1);
}

uint8_t ack[] = {0x01};
uint8_t nack[] = {0xFE};
void receive() {
	UpdateTarget target;

	HAL_UART_Receive(&huart1, &target, 1, 1000);
	HAL_UART_Transmit(&huart1, ack, sizeof(ack), HAL_MAX_DELAY);

	uint8_t length_buffer[2];
	HAL_UART_Receive(&huart1, length_buffer, sizeof(length_buffer), HAL_MAX_DELAY);
	HAL_UART_Transmit(&huart1, length_buffer, sizeof(length_buffer), HAL_MAX_DELAY);
	uint16_t length = length_buffer[0] + (length_buffer[1] << 8);

	uint8_t* data = malloc(length);
	HAL_UART_Receive(&huart1, data, length, 1000);

	// Calculate the CRC of the data and send it back
	// @todo Figure how we can actually use the hardware crc
	/* uint32_t crc = HAL_CRC_Calculate(&hcrc, (uint32_t*)data, length); */
	uint32_t crc = crc32(data, length);
	uint8_t c[] = {crc, crc >> 8, crc >> 16, crc >> 24};
	HAL_UART_Transmit(&huart1, c, sizeof(c), HAL_MAX_DELAY);

	switch (target) {
		case TARGET_I2C: {
			 // Unlock flash
			 HAL_FLASH_Unlock();
			 HAL_UART_Transmit(&huart1, ack, sizeof(ack), HAL_MAX_DELAY);

			 // Erase flash
			 uint32_t error = 0;
			 FLASH_EraseInitTypeDef erase = {
				 .TypeErase = FLASH_TYPEERASE_PAGES,
				 .PageAddress = (uint32_t)0x8004000,
				 .NbPages = ceil(length/1024.0f),
			 };
			 HAL_FLASHEx_Erase(&erase, &error);

			 // Write to flash
			 for (int i = 0; i < length/2; ++i) {
				 if (HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, 0x8004000 + i*2, ((uint16_t*)data)[i])) {
					 return;
				 }
				 uint8_t progress[] = {(i*2) & 0xFF, (i*2) >> 8};
				 HAL_UART_Transmit(&huart1, progress, sizeof(progress), HAL_MAX_DELAY);
			 }
			 uint8_t progress[] = {(length) & 0xFF, (length) >> 8};
			 HAL_UART_Transmit(&huart1, progress, sizeof(progress), HAL_MAX_DELAY);

			 // Done
			 HAL_FLASH_Lock();
			 HAL_UART_Transmit(&huart1, ack, sizeof(ack), HAL_MAX_DELAY);

			 should_start_user_program = 1;

			 break;
		 }

		default:
			 printf("Target not implemented!\n\r");
			 break;

	}
}

uint8_t byte;
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
	if (huart->Instance == USART1) {
		static uint8_t command_mode = 0;

		if (command_mode) {
			switch (byte) {
				// Upload firmware
				case 'u':
					HAL_UART_Transmit(&huart1, ack, sizeof(ack), HAL_MAX_DELAY);
					receive();
					break;

				default:
					HAL_UART_Transmit(&huart1, nack, sizeof(nack), HAL_MAX_DELAY);
					break;
			}
			command_mode = 0;
		} else if (byte == 0xFF) {
			command_mode = 1;
			HAL_UART_Transmit(&huart1, ack, sizeof(ack), HAL_MAX_DELAY);
		}

		HAL_UART_Receive_IT(&huart1, &byte, 1);
	}
}

int _isatty(int fd) {
	if (fd >= STDIN_FILENO && fd <= STDERR_FILENO) {
		return 1;
	}

	errno = EBADF;
	return 0;
}

int _write(int fd, char* ptr, int len) {
	HAL_StatusTypeDef hstatus;

	if (fd >= STDIN_FILENO && fd <= STDERR_FILENO) {
		hstatus = HAL_UART_Transmit(&huart1, (uint8_t*)ptr, len, HAL_MAX_DELAY);
		if (hstatus == HAL_OK) {
			return len;
		} else {
			return EIO;
		}
	}
	errno = EBADF;
	return -1;
}

int _close(int fd) {
	if (fd >= STDIN_FILENO && fd <= STDERR_FILENO) {
		return 0;
	}

	errno = EBADF;
	return -1;
}

int _lseek(int fd, int ptr, int dir) {
	(void) fd;
	(void) ptr;
	(void) dir;

	errno = EBADF;
	return -1;
}

int _read(int fd, char* ptr, int len) {
	HAL_StatusTypeDef hstatus;

	if (fd == STDIN_FILENO) {
		hstatus = HAL_UART_Receive(&huart1, (uint8_t*)ptr, 1, HAL_MAX_DELAY);
		if (hstatus == HAL_OK) {
			return 1;
		} else {
			return EIO;
		}
	}
	errno = EBADF;
	return -1;
}

int _fstat(int fd, struct stat* st) {
	if (fd >= STDIN_FILENO && fd <= STDERR_FILENO) {
		st->st_mode = S_IFCHR;
		return 0;
	}

	errno = EBADF;
	return 0;
}

uint16_t get_magic_value() {
	RCC->APB1ENR |= (1 << 27 | 1 << 28);

	uint16_t value = BKP->DR10;

	if (value) {
		PWR->CR |= (1 << 8);

		BKP->DR10 = 0;

		PWR->CR &= ~(1 << 8);
	}

	RCC->APB1ENR &= ~(1 << 27 | 1 << 28);

	return value;
}

void set_magic_value() {
	RCC->APB1ENR |= (1 << 27 | 1 << 28);
	PWR->CR |= (1 << 8);

	BKP->DR10 = 0xB007;

	PWR->CR &= ~(1 << 8);
	RCC->APB1ENR &= ~(1 << 27 | 1 << 28);
}

/* USER CODE END 0 */

/**
 * @brief  The application entry point.
 * @retval int
 */
int main(void)
{
	/* USER CODE BEGIN 1 */

	/* USER CODE END 1 */

	/* MCU Configuration--------------------------------------------------------*/

	/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
	HAL_Init();

	/* USER CODE BEGIN Init */

	/* USER CODE END Init */

	/* Configure the system clock */
	SystemClock_Config();

	/* USER CODE BEGIN SysInit */

	/* USER CODE END SysInit */

	/* Initialize all configured peripherals */
	MX_GPIO_Init();
	MX_USART1_UART_Init();
	/* USER CODE BEGIN 2 */
	setvbuf(stdout, NULL, _IONBF, 0);

	printf("Bootloader started\n\r");

	// @todo We also need to detect errors/request to enter bootloader incase the program misbehaves
	uint16_t magic_value = get_magic_value();
	if (magic_value != 0xB007) {
		// We set the magic value before starting the program just to test everything easily
		set_magic_value();

		printf("\tStarting application\n\r");

		start_user_program();
	}

	printf("\tAwaiting command\n\r");
	HAL_UART_Receive_IT(&huart1, &byte, 1);

	// Run the bootloader
	// @todo Start interrupt for HAL_UART
	// When it received the correct command it will run the receive routine
	/* USER CODE END 2 */

	/* Infinite loop */
	/* USER CODE BEGIN WHILE */
	while (1)
	{
		if (should_start_user_program) {
			// We set the magic value before starting the program just to test everything easily
			set_magic_value();
			start_user_program();
		}
		HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_RESET);
		HAL_Delay(100);
		HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_SET);
		HAL_Delay(100);
		/* USER CODE END WHILE */

		/* USER CODE BEGIN 3 */
	}
	/* USER CODE END 3 */
}

/**
 * @brief System Clock Configuration
 * @retval None
 */
void SystemClock_Config(void)
{
	RCC_OscInitTypeDef RCC_OscInitStruct = {0};
	RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

	/** Initializes the RCC Oscillators according to the specified parameters
	 * in the RCC_OscInitTypeDef structure.
	 */
	RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
	RCC_OscInitStruct.HSEState = RCC_HSE_ON;
	RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
	RCC_OscInitStruct.HSIState = RCC_HSI_ON;
	RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
	RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
	RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
	if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
	{
		Error_Handler();
	}
	/** Initializes the CPU, AHB and APB buses clocks
	*/
	RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
		|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
	RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
	RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
	RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
	RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

	if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
	{
		Error_Handler();
	}
}

/**
 * @brief USART1 Initialization Function
 * @param None
 * @retval None
 */
static void MX_USART1_UART_Init(void)
{

	/* USER CODE BEGIN USART1_Init 0 */

	/* USER CODE END USART1_Init 0 */

	/* USER CODE BEGIN USART1_Init 1 */

	/* USER CODE END USART1_Init 1 */
	huart1.Instance = USART1;
	huart1.Init.BaudRate = 115200;
	huart1.Init.WordLength = UART_WORDLENGTH_8B;
	huart1.Init.StopBits = UART_STOPBITS_1;
	huart1.Init.Parity = UART_PARITY_NONE;
	huart1.Init.Mode = UART_MODE_TX_RX;
	huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
	huart1.Init.OverSampling = UART_OVERSAMPLING_16;
	if (HAL_UART_Init(&huart1) != HAL_OK)
	{
		Error_Handler();
	}
	/* USER CODE BEGIN USART1_Init 2 */

	/* USER CODE END USART1_Init 2 */

}

/**
 * @brief GPIO Initialization Function
 * @param None
 * @retval None
 */
static void MX_GPIO_Init(void)
{
	GPIO_InitTypeDef GPIO_InitStruct = {0};

	/* GPIO Ports Clock Enable */
	__HAL_RCC_GPIOC_CLK_ENABLE();
	__HAL_RCC_GPIOD_CLK_ENABLE();
	__HAL_RCC_GPIOA_CLK_ENABLE();

	/*Configure GPIO pin Output Level */
	HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_RESET);

	/*Configure GPIO pin : PC13 */
	GPIO_InitStruct.Pin = GPIO_PIN_13;
	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
	GPIO_InitStruct.Pull = GPIO_NOPULL;
	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
	HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);

}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
 * @brief  This function is executed in case of error occurrence.
 * @retval None
 */
void Error_Handler(void)
{
	/* USER CODE BEGIN Error_Handler_Debug */
	/* User can add his own implementation to report the HAL error return state */
	__disable_irq();
	while (1)
	{
	}
	/* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
 * @brief  Reports the name of the source file and the source line number
 *         where the assert_param error has occurred.
 * @param  file: pointer to the source file name
 * @param  line: assert_param error line source number
 * @retval None
 */
void assert_failed(uint8_t *file, uint32_t line)
{
	/* USER CODE BEGIN 6 */
	/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
	/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/