#include "stm32c0xx_hal.h"

// Define pins for digits and segments
#define DIGIT_1_PIN GPIO_PIN_0
#define DIGIT_2_PIN GPIO_PIN_1
#define DIGIT_3_PIN GPIO_PIN_2
#define DIGIT_4_PIN GPIO_PIN_3
#define DIGIT_PORT GPIOD

#define SEG_A_PIN GPIO_PIN_0
#define SEG_B_PIN GPIO_PIN_1
#define SEG_C_PIN GPIO_PIN_2
#define SEG_D_PIN GPIO_PIN_3
#define SEG_E_PIN GPIO_PIN_4
#define SEG_F_PIN GPIO_PIN_5
#define SEG_G_PIN GPIO_PIN_6
#define SEG_DP_PIN GPIO_PIN_7
#define SEGMENT_PORT GPIOA

// Segment patterns for digits 0-9 (common anode - inverted logic)
const uint8_t digit_patterns[10] = {
    0xC0, // 0
    0xF9, // 1
    0xA4, // 2
    0xB0, // 3
    0x99, // 4
    0x92, // 5
    0x82, // 6
    0xF8, // 7
    0x80, // 8
    0x90  // 9
};

uint8_t display_buffer[4] = {0}; // Display buffer for each digit
uint8_t current_digit = 0;       // Currently active digit
uint32_t last_display_update = 0;

void setup() {
    // Enable GPIO clocks
    __HAL_RCC_GPIOA_CLK_ENABLE();
    __HAL_RCC_GPIOD_CLK_ENABLE();
    
    // Configure digit pins as output
    GPIO_InitTypeDef GPIO_InitStruct = {0};
    GPIO_InitStruct.Pin = DIGIT_1_PIN | DIGIT_2_PIN | DIGIT_3_PIN | DIGIT_4_PIN;
    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    HAL_GPIO_Init(DIGIT_PORT, &GPIO_InitStruct);
    
    // Configure segment pins as output
    GPIO_InitStruct.Pin = SEG_A_PIN | SEG_B_PIN | SEG_C_PIN | SEG_D_PIN | 
                         SEG_E_PIN | SEG_F_PIN | SEG_G_PIN | SEG_DP_PIN;
    HAL_GPIO_Init(SEGMENT_PORT, &GPIO_InitStruct);
    
    // Turn off all digits initially
    HAL_GPIO_WritePin(DIGIT_PORT, DIGIT_1_PIN | DIGIT_2_PIN | DIGIT_3_PIN | DIGIT_4_PIN, GPIO_PIN_RESET);
    
    // Set initial display value
    display_buffer[0] = 1;
    display_buffer[1] = 2;
    display_buffer[2] = 3;
    display_buffer[3] = 4;
}

void loop() {
    uint32_t now = HAL_GetTick();
    
    // Update display every 5ms
    if (now - last_display_update >= 5) {
        // Turn off all digits
        HAL_GPIO_WritePin(DIGIT_PORT, DIGIT_1_PIN | DIGIT_2_PIN | DIGIT_3_PIN | DIGIT_4_PIN, GPIO_PIN_RESET);
        
        // Set segments for current digit
        uint8_t pattern = digit_patterns[display_buffer[current_digit]];
        SEGMENT_PORT->ODR = (SEGMENT_PORT->ODR & 0xFF00) | pattern;
        
        // Enable current digit
        switch(current_digit) {
            case 0: HAL_GPIO_WritePin(DIGIT_PORT, DIGIT_1_PIN, GPIO_PIN_SET); break;
            case 1: HAL_GPIO_WritePin(DIGIT_PORT, DIGIT_2_PIN, GPIO_PIN_SET); break;
            case 2: HAL_GPIO_WritePin(DIGIT_PORT, DIGIT_3_PIN, GPIO_PIN_SET); break;
            case 3: HAL_GPIO_WritePin(DIGIT_PORT, DIGIT_4_PIN, GPIO_PIN_SET); break;
        }
        
        // Move to next digit
        current_digit = (current_digit + 1) % 4;
        
        last_display_update = now;
    }
    
    // For example, increment the display value every second
    static uint32_t last_counter_update = 0;
    static uint16_t counter = 0;
    
    if (now - last_counter_update >= 1000) {
        counter++;
        if (counter > 9999) counter = 0;
        
        // Update display buffer
        display_buffer[0] = counter / 1000;
        display_buffer[1] = (counter / 100) % 10;
        display_buffer[2] = (counter / 10) % 10;
        display_buffer[3] = counter % 10;
        
        last_counter_update = now;
    }
}

int main(void) {
    HAL_Init();
    setup();
    
    while (1) {
        loop();
    }
}