#include "stm32f4xx_hal.h"

#define BUFFER_SIZE 100

// Circular buffer structure
typedef struct {
    uint8_t buffer[BUFFER_SIZE];
    uint32_t head;
    uint32_t tail;
} CircularBuffer;

CircularBuffer rxBuffer;

// Flag to indicate continuous data reading from port D
volatile uint8_t continuousRead = 0;

// External interrupt callback function
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin) {
    // Check if the interrupt is from the expected pin
    if (GPIO_Pin == GPIO_PIN_0) {
        continuousRead = 1; // Set the flag for continuous reading
    }
}

int main(void) {
    HAL_Init();
    // Initialize the HAL Library
    HAL_Init();

    // Configure GPIO pins for external interrupt and port D for input
    GPIO_InitTypeDef GPIO_InitStruct;
    __HAL_RCC_GPIOD_CLK_ENABLE();

    GPIO_InitStruct.Pin = GPIO_PIN_0;
    GPIO_InitStruct.Mode = GPIO_MODE_IT_FALLING;
    GPIO_InitStruct.Pull = GPIO_PULLUP;
    HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);

    // Enable and set EXTI line 0 Interrupt to the lowest priority
    HAL_NVIC_SetPriority(EXTI0_IRQn, 2, 0);
    HAL_NVIC_EnableIRQ(EXTI0_IRQn);

    // Initialize circular buffer
    rxBuffer.head = 0;
    rxBuffer.tail = 0;

    while (1) {
        // Continuously read from port D if the flag is set
        if (continuousRead) {
            // Read data from port D and store it in the circular buffer
            rxBuffer.buffer[rxBuffer.head] = GPIOB->IDR & 0xFF; // Assuming port D
            rxBuffer.head = (rxBuffer.head + 1) % BUFFER_SIZE;
        }

        // Process the data
        if (rxBuffer.head != rxBuffer.tail) {
            uint8_t data = rxBuffer.buffer[rxBuffer.tail];
            // Your processing code here
            rxBuffer.tail = (rxBuffer.tail + 1) % BUFFER_SIZE;
        }

        // Clear the flag after processing data
        continuousRead = 0;
    }
}

// EXTI0 interrupt handler
void EXTI0_IRQHandler(void) {
    HAL_GPIO_EXTI_IRQHandler(GPIO_PIN_0);
}