#include "stm32c0xx_hal.h"

volatile int mode = 0;
volatile int brightness = 0;
volatile int direction = 1;

void delay(volatile uint32_t t)
{
    while(t--);
}

// Software PWM
void pwm_rgb(int r, int g, int b, int bright)
{
    for(int i=0; i<100; i++)
    {
        if(i < bright)
        {
            if(r) GPIOA->BSRR = (1 << 0);
            else  GPIOA->BRR  = (1 << 0);

            if(g) GPIOA->BSRR = (1 << 1);
            else  GPIOA->BRR  = (1 << 1);

            if(b) GPIOA->BSRR = (1 << 2);
            else  GPIOA->BRR  = (1 << 2);
        }
        else
        {
            GPIOA->BRR = (1 << 0);
            GPIOA->BRR = (1 << 1);
            GPIOA->BRR = (1 << 2);
        }

        delay(50);
    }
}

int main(void)
{
    // GPIOA clock
    RCC->IOPENR |= RCC_IOPENR_GPIOAEN;

    // PA0 PA1 PA2 output
    GPIOA->MODER &= ~(0x3F);
    GPIOA->MODER |=  (0x15);

    // PA3 input
    GPIOA->MODER &= ~(3 << (3 * 2));

    // pull-up
    GPIOA->PUPDR &= ~(3 << (3 * 2));
    GPIOA->PUPDR |=  (1 << (3 * 2));

    int old_button = 1;
    int rainbow_step = 0;

    while(1)
    {
        // knopka o‘qish
        int button = (GPIOA->IDR & (1 << 3));

        // bosildi
        if(!button && old_button)
        {
            mode++;

            if(mode > 3)
                mode = 0;

            delay(300000);
        }

        old_button = button;

        // brightness o‘zgarishi
        brightness += direction;

        if(brightness >= 100)
            direction = -1;

        if(brightness <= 0)
            direction = 1;

        // mode lar
        switch(mode)
        {
            case 0:
                pwm_rgb(1,0,0,brightness);
                break;

            case 1:
                pwm_rgb(0,1,0,brightness);
                break;

            case 2:
                pwm_rgb(0,0,1,brightness);
                break;

            case 3:

                switch(rainbow_step)
                {
                    case 0:
                        pwm_rgb(1,0,0,brightness);
                        break;

                    case 1:
                        pwm_rgb(0,1,0,brightness);
                        break;

                    case 2:
                        pwm_rgb(0,0,1,brightness);
                        break;

                    case 3:
                        pwm_rgb(1,1,0,brightness);
                        break;

                    case 4:
                        pwm_rgb(1,0,1,brightness);
                        break;

                    case 5:
                        pwm_rgb(0,1,1,brightness);
                        break;
                }

                // brightness tugaganda keyingi rang
                if(brightness == 0)
                {
                    rainbow_step++;

                    if(rainbow_step > 5)
                        rainbow_step = 0;
                }

                break;
        }
    }
}