#include "stm32c0xx.h"
#include "stm32c0xx_hal.h"
#include <stdio.h>

const uint8_t DANIEL[6][8] = {
    {0XFF, 0XFF, 0X18, 0X18, 0X18, 0X18, 0X1F, 0X1F}, // J
    {0xFF, 0x03, 0x03, 0xFF, 0xFF, 0x03, 0x03, 0xFF}, // E
    {0xFF, 0xFF, 0x01, 0xFF, 0xFF, 0x80, 0xFF, 0xFF}, // S
    {0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xFF, 0xFF}, // U
    {0xFF, 0xFF, 0x01, 0xFF, 0xFF, 0x80, 0xFF, 0xFF}, // S
    {0x00, 0x66, 0xFF, 0xFF, 0xFF, 0x7E, 0x3C, 0x18}  // LOVES U
};


// MAX7219 REGISTER MAP
typedef enum {
    MAX7219_REG_NOOP        = 0x00,
    MAX7219_REG_DIGIT0      = 0x01,
    MAX7219_REG_DIGIT1      = 0x02,
    MAX7219_REG_DIGIT2      = 0x03,
    MAX7219_REG_DIGIT3      = 0x04,
    MAX7219_REG_DIGIT4      = 0x05,
    MAX7219_REG_DIGIT5      = 0x06,
    MAX7219_REG_DIGIT6      = 0x07,
    MAX7219_REG_DIGIT7      = 0x08,
    MAX7219_REG_DECODE      = 0x09,
    MAX7219_REG_INTENSITY   = 0x0A,
    MAX7219_REG_SCANLIMIT   = 0x0B,
    MAX7219_REG_SHUTDOWN    = 0x0C,
    MAX7219_REG_DISPLAYTEST = 0x0F
} MAX7219_Registers;

typedef enum {
    CS_PIN = 4, CLK_PIN = 5, DATA_PIN = 6 
} MAX7219_Pins;

typedef union {
    uint16_t raw;
    struct {
        uint16_t data:8;
        uint16_t address:4;
        uint16_t unused:4;
    } fields;
} MAX7219_cmd;

/*
*  Here you initialize all the functions that you create
*/

// Initializing the LCD by using TEST MODE
void MAX7219_INIT(MAX7219_cmd cmd);
void SEND_MAX7219_CMD(uint16_t command_word);


// Initialize GPIO
void GPIO_Init() {
    RCC->IOPENR |= RCC_IOPENR_GPIOAEN; // Enable GPIOA clock
    
    // Set PA4,5,6 as output
    GPIOA->MODER &= ~(GPIO_MODER_MODE4 | GPIO_MODER_MODE5 | GPIO_MODER_MODE6);
    GPIOA->MODER |= (GPIO_MODER_MODE4_0 | GPIO_MODER_MODE5_0 | GPIO_MODER_MODE6_0);
    
    // Initial states
    GPIOA->ODR |= (1 << CS_PIN) | (1 << CLK_PIN); // CS and CLK high
    GPIOA->ODR &= ~(1 << DATA_PIN); // DATA low
}



int main(void) {
    
    HAL_Init();
    
    // Configure the system clock
    SystemClock_Config();
    
    GPIO_Init();
    // printf("GPIO Initialized\n");
    MAX7219_cmd cmd;

    MAX7219_INIT(cmd);

    

    while(1){

      for (uint8_t col = 0; col < 6; col++) {
          for (uint8_t row = 0; row < 8; row++) {
              cmd.fields.address = row + 1;
              cmd.fields.data = DANIEL[col][row];
              
              SEND_MAX7219_CMD(cmd.raw);
          }

          HAL_Delay(1000);  // 1-second delay
      }

    };
}

void MAX7219_INIT(MAX7219_cmd cmd) {
  /*
  * Note that the LCD is initialize in shutdown mode, based on
  * the documentation
  */

  //1. Wake up from shutdown
  cmd.fields.address = MAX7219_REG_SHUTDOWN;
  cmd.fields.data = 0x01;
  SEND_MAX7219_CMD(cmd.raw);

  //2. SET SCAN LIMIT
  cmd.fields.address = MAX7219_REG_SCANLIMIT;
  cmd.fields.data = 0x07;
  SEND_MAX7219_CMD(cmd.raw);

  //3. Disable BCD
  cmd.fields.address = MAX7219_REG_DECODE;
  cmd.fields.data = 0x00;
  SEND_MAX7219_CMD(cmd.raw);

  //4. Set brightness
  cmd.fields.address = MAX7219_REG_INTENSITY;
  cmd.fields.data = 0x0F; // Max brightness
  SEND_MAX7219_CMD(cmd.raw);

}

void SEND_MAX7219_CMD(uint16_t command_word){
    
    //PIN was high, then set to 0
    GPIOA->ODR &= ~(1 << CS_PIN);
    //Loop through the data, starting with the MSB
    for (int8_t i=15; i>=0; i--) {

        //set CLk to low
        GPIOA->ODR &= ~(1 << CLK_PIN);

        if (command_word & (1 << i)) {
          GPIOA->ODR |= (1 << DATA_PIN);
        } else {
          GPIOA->ODR &= ~(1 << DATA_PIN);
        }
        // delayMicroseconds(50);
        GPIOA->ODR |= (1 << CLK_PIN);
        // delayMicroseconds(50);
    }
    //Pin is 0, then set to 1
    
    GPIOA->ODR |= (1<< CS_PIN);

    // delayMicroseconds(100);
    

}