/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2026 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "string.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include"csprng.h"
#include <stdlib.h>
struct entropy_pool s_entropy;

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

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

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

ETH_TxPacketConfig TxConfig;
ETH_DMADescTypeDef  DMARxDscrTab[ETH_RX_DESC_CNT]; /* Ethernet Rx DMA Descriptors */
ETH_DMADescTypeDef  DMATxDscrTab[ETH_TX_DESC_CNT]; /* Ethernet Tx DMA Descriptors */

ETH_HandleTypeDef heth;

RNG_HandleTypeDef hrng;

UART_HandleTypeDef huart3;
UART_HandleTypeDef huart6;

PCD_HandleTypeDef hpcd_USB_OTG_FS;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_ETH_Init(void);
static void MX_USART3_UART_Init(void);
static void MX_USB_OTG_FS_PCD_Init(void);
static void MX_RNG_Init(void);
static void MX_USART6_UART_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/*
 * Fill the entropy structure with random data
 */
void init_entropy(){

  // Generate entropy
  memset(&s_entropy, 0, sizeof(s_entropy));

  while(s_entropy.pool_size < BUFSIZE){
      generateEntropy(s_entropy.position++);
      s_entropy.pool_size++;

      // Add a delay for avoiding the same value
      //delay(50);
  }
  /* We start at 0, ready for pickup to the pool */
  s_entropy.position = 0;
}

/*
 * Generate a random value from the analog input
 * Store the value in the entropy structure at the position specified in argument
 */
static void generateEntropy(int position){
  unsigned int sensorValue = 0;

  //RNG->CR|=RNG_CR_RNGEN;
  RNG->CR = RNG_CR_RNGEN; /* RNG_CR_RNGEN -> 4 */

  while (sensorValue == 0){
    HAL_GPIO_TogglePin (GPIOB, GPIO_PIN_0);
    HAL_Delay (100);   /* Insert delay 100 ms */

	// Wait until the data is ready
	while (RNG_SR_DRDY == 0);

    uint32_t random = RNG->DR;

    sensorValue = abs(random);

    if (sensorValue != 0){
      if(sensorValue <= 10)
        sensorValue = sensorValue << 5;
      else if(sensorValue > 10 && sensorValue <= 100)
        sensorValue = sensorValue << 4;

      s_entropy.buf[position] = sensorValue;
    }
  }
}

/*
 * Pick a random data from the entropy pool
 * This function is the API function to get the random number from the pool
 */
unsigned int prng(){
    unsigned int p = 0;

    if (s_entropy.position == BUFSIZE)
        s_entropy.position = 0;

    // We consume the entropy
    p = s_entropy.buf[s_entropy.position];
    s_entropy.pool_size--;

    // We have consumed the entropy, we replace the value by a new one
    generateEntropy(s_entropy.position);

    s_entropy.position++;

    return p;
}

/*
 * For the Blum-Blum-Shub, we need to find a prime number and must be congruent 3 modulo 4
 */
static void prime_number_finder(unsigned int *p){
    while(!isPrimeNumber(*p) || (*p % 4 != 3))
        *p += 1;
}
/*
 * Check if the number specified is a prime number
 */
static int isPrimeNumber(unsigned int x){
    for (int i = 0; i < SIEVES_LEN; i++){
        if (x % sieves[i] == 0)
            return 0;
    }
    return 1;
}
/*
 * This function find the GCD
 */
static int gcd(unsigned long a, unsigned long b){
    if (b == 0)
        return a;
    return gcd(b, a % b);
}

unsigned int random_range(int min, int max){
	// Wait until the data is ready
	while (RNG_SR_DRDY == 0);

    uint32_t random = RNG->DR;
    return (random % max) + 1;
}

static unsigned short csum(unsigned short *buf, int nwords) {
    unsigned long sum = 0;
    while (nwords > 0) {
        sum += *buf++;
        nwords--;
    }
    sum = (sum >> 16) + (sum & 0xFFFF);
    sum += (sum >> 16);
    return (unsigned short)(~sum);
}

/*
 * This function implement the Blum-Blum-Shub algorithm
 * Based on the algorithm described in the Chapter 5:
 *   https://cacr.uwaterloo.ca/hac/about/chap5.pdf
 */
static unsigned long long bbs(unsigned int *p, unsigned int *q, unsigned long long *s){
    /* We pickup data from the entropy pool */
    unsigned int p1 = prng();
    unsigned int p2 = prng();
    unsigned long long n = 0, seed = 0;

    // We check if they are prime numbers
    prime_number_finder(&p1);
    prime_number_finder(&p2);
    *p = p1;
    *q = p2;

    n = (unsigned long long)p1 * (unsigned long long)p2;

    /*
     * We need to find the seed
     * between 1 < s < n - 1 and gcd(s, n) = 1
     */
    seed = random_range(1, n);
    while (gcd(seed, n) != 1)
        seed += 1;
    *s = seed;

    unsigned long long x0 = (seed * seed) % n;

    unsigned long long tmp = x0;

    char output[ITER_BBS];
    memset(output, 0, ITER_BBS);
    int pos = 0;
    for (size_t i = 1; i < ITER_BBS; i++){
        unsigned long long x = (tmp * tmp) % n;
        output[pos++] = (x & 1) + '0';
        tmp = x;
    }

    /* We convert the bit sequence to unsigned long long */
    unsigned long long res = 0;
    for (int i = 0; i < strlen(output); i++)
        res = (res << 1) + output[i] - '0';

    return res;
}


/* 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_ETH_Init();
  MX_USART3_UART_Init();
  MX_USB_OTG_FS_PCD_Init();
  MX_RNG_Init();
  MX_USART6_UART_Init();
  /* USER CODE BEGIN 2 */
  init_entropy();

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */


  uint8_t buffer[sizeof(struct prng)];
  uint8_t buf_recv[sizeof(struct cmd)];

  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
	HAL_StatusTypeDef status = HAL_UART_Receive(&huart6, buf_recv, sizeof(struct cmd), 100);

	if (status == HAL_OK){
     struct cmd *s_cmd = (struct cmd *)buf_recv;
	 if (s_cmd->cmd == CSPRNG_CMD_GET_RNG){
		 struct prng s_prng = {0};

		 memset(buffer, 0, sizeof(struct prng));
		 HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0, GPIO_PIN_SET);


		 unsigned long long random = bbs(&s_prng.p, &s_prng.q, &s_prng.seed);
		 s_prng.output = random;
		 memcpy(buffer, &s_prng, sizeof(struct prng));

		 HAL_StatusTypeDef s = HAL_UART_Transmit(&huart6, buffer, sizeof(struct prng), 0xF);

		 // We have finished, we disable the pin
		 HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0, GPIO_PIN_RESET);
	  }
	}

  }
  /* USER CODE END 3 */
}

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

  /** Configure the main internal regulator output voltage
  */
  __HAL_RCC_PWR_CLK_ENABLE();
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

  /** 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_BYPASS;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLM = 4;
  RCC_OscInitStruct.PLL.PLLN = 168;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
  RCC_OscInitStruct.PLL.PLLQ = 7;
  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_DIV4;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief ETH Initialization Function
  * @param None
  * @retval None
  */
static void MX_ETH_Init(void)
{

  /* USER CODE BEGIN ETH_Init 0 */

  /* USER CODE END ETH_Init 0 */

   static uint8_t MACAddr[6];

  /* USER CODE BEGIN ETH_Init 1 */

  /* USER CODE END ETH_Init 1 */
  heth.Instance = ETH;
  MACAddr[0] = 0x00;
  MACAddr[1] = 0x80;
  MACAddr[2] = 0xE1;
  MACAddr[3] = 0x00;
  MACAddr[4] = 0x00;
  MACAddr[5] = 0x00;
  heth.Init.MACAddr = &MACAddr[0];
  heth.Init.MediaInterface = HAL_ETH_RMII_MODE;
  heth.Init.TxDesc = DMATxDscrTab;
  heth.Init.RxDesc = DMARxDscrTab;
  heth.Init.RxBuffLen = 1524;

  /* USER CODE BEGIN MACADDRESS */

  /* USER CODE END MACADDRESS */

  if (HAL_ETH_Init(&heth) != HAL_OK)
  {
    Error_Handler();
  }

  memset(&TxConfig, 0 , sizeof(ETH_TxPacketConfig));
  TxConfig.Attributes = ETH_TX_PACKETS_FEATURES_CSUM | ETH_TX_PACKETS_FEATURES_CRCPAD;
  TxConfig.ChecksumCtrl = ETH_CHECKSUM_IPHDR_PAYLOAD_INSERT_PHDR_CALC;
  TxConfig.CRCPadCtrl = ETH_CRC_PAD_INSERT;
  /* USER CODE BEGIN ETH_Init 2 */

  /* USER CODE END ETH_Init 2 */

}

/**
  * @brief RNG Initialization Function
  * @param None
  * @retval None
  */
static void MX_RNG_Init(void)
{

  /* USER CODE BEGIN RNG_Init 0 */

  /* USER CODE END RNG_Init 0 */

  /* USER CODE BEGIN RNG_Init 1 */

  /* USER CODE END RNG_Init 1 */
  hrng.Instance = RNG;
  if (HAL_RNG_Init(&hrng) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN RNG_Init 2 */

  /* USER CODE END RNG_Init 2 */

}

/**
  * @brief USART3 Initialization Function
  * @param None
  * @retval None
  */
static void MX_USART3_UART_Init(void)
{

  /* USER CODE BEGIN USART3_Init 0 */

  /* USER CODE END USART3_Init 0 */

  /* USER CODE BEGIN USART3_Init 1 */

  /* USER CODE END USART3_Init 1 */
  huart3.Instance = USART3;
  huart3.Init.BaudRate = 115200;
  huart3.Init.WordLength = UART_WORDLENGTH_8B;
  huart3.Init.StopBits = UART_STOPBITS_1;
  huart3.Init.Parity = UART_PARITY_NONE;
  huart3.Init.Mode = UART_MODE_TX_RX;
  huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart3.Init.OverSampling = UART_OVERSAMPLING_16;
  if (HAL_UART_Init(&huart3) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART3_Init 2 */

  /* USER CODE END USART3_Init 2 */

}

/**
  * @brief USART6 Initialization Function
  * @param None
  * @retval None
  */
static void MX_USART6_UART_Init(void)
{

  /* USER CODE BEGIN USART6_Init 0 */

  /* USER CODE END USART6_Init 0 */

  /* USER CODE BEGIN USART6_Init 1 */

  /* USER CODE END USART6_Init 1 */
  huart6.Instance = USART6;
  huart6.Init.BaudRate = 115200;
  huart6.Init.WordLength = UART_WORDLENGTH_8B;
  huart6.Init.StopBits = UART_STOPBITS_1;
  huart6.Init.Parity = UART_PARITY_NONE;
  huart6.Init.Mode = UART_MODE_TX_RX;
  huart6.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart6.Init.OverSampling = UART_OVERSAMPLING_16;
  if (HAL_UART_Init(&huart6) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART6_Init 2 */

  /* USER CODE END USART6_Init 2 */

}

/**
  * @brief USB_OTG_FS Initialization Function
  * @param None
  * @retval None
  */
static void MX_USB_OTG_FS_PCD_Init(void)
{

  /* USER CODE BEGIN USB_OTG_FS_Init 0 */

  /* USER CODE END USB_OTG_FS_Init 0 */

  /* USER CODE BEGIN USB_OTG_FS_Init 1 */

  /* USER CODE END USB_OTG_FS_Init 1 */
  hpcd_USB_OTG_FS.Instance = USB_OTG_FS;
  hpcd_USB_OTG_FS.Init.dev_endpoints = 4;
  hpcd_USB_OTG_FS.Init.speed = PCD_SPEED_FULL;
  hpcd_USB_OTG_FS.Init.dma_enable = DISABLE;
  hpcd_USB_OTG_FS.Init.phy_itface = PCD_PHY_EMBEDDED;
  hpcd_USB_OTG_FS.Init.Sof_enable = ENABLE;
  hpcd_USB_OTG_FS.Init.low_power_enable = DISABLE;
  hpcd_USB_OTG_FS.Init.lpm_enable = DISABLE;
  hpcd_USB_OTG_FS.Init.vbus_sensing_enable = ENABLE;
  hpcd_USB_OTG_FS.Init.use_dedicated_ep1 = DISABLE;
  if (HAL_PCD_Init(&hpcd_USB_OTG_FS) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USB_OTG_FS_Init 2 */

  /* USER CODE END USB_OTG_FS_Init 2 */

}

/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  /* USER CODE BEGIN MX_GPIO_Init_1 */

  /* USER CODE END MX_GPIO_Init_1 */

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

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOB, LD1_Pin|LD3_Pin|LD2_Pin, GPIO_PIN_RESET);

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(USB_PowerSwitchOn_GPIO_Port, USB_PowerSwitchOn_Pin, GPIO_PIN_RESET);

  /*Configure GPIO pin : USER_Btn_Pin */
  GPIO_InitStruct.Pin = USER_Btn_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(USER_Btn_GPIO_Port, &GPIO_InitStruct);

  /*Configure GPIO pins : LD1_Pin LD3_Pin LD2_Pin */
  GPIO_InitStruct.Pin = LD1_Pin|LD3_Pin|LD2_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

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

  /*Configure GPIO pin : USB_OverCurrent_Pin */
  GPIO_InitStruct.Pin = USB_OverCurrent_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(USB_OverCurrent_GPIO_Port, &GPIO_InitStruct);

  /* USER CODE BEGIN MX_GPIO_Init_2 */

  /* USER CODE END MX_GPIO_Init_2 */
}

/* USER CODE BEGIN 4 */
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
  if (huart->Instance == USART3)
	  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0, GPIO_PIN_RESET);
}
/* 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 */