/* Single-File-Header for using asynchronous LEDs with the CH32V003 using GPIO.

   Copyright 2023 <>< Charles Lohr, under the MIT-x11 or NewBSD License, you choose!

   If you are including this in main, simply
        #define WS2812BSIMPLE_IMPLEMENTATION

   You may also want to define
        #define WS2812BSIMPLE_NO_IRQ_TWEAKING

*/

#ifndef _WS2812B_SIMPLE
#define _WS2812B_SIMPLE

#include <stdint.h>

void WS2812BSimpleSend(GPIO_TypeDef *port, int pin, uint8_t *data, int len_in_bytes);

#ifdef WS2812BSIMPLE_IMPLEMENTATION

#include "funconfig.h"

#if FUNCONF_SYSTICK_USE_HCLK != 1
#error WS2812B Driver Requires FUNCONF_SYSTICK_USE_HCLK
#endif

void WS2812BSimpleSend(GPIO_TypeDef *port, int pin, uint8_t *data, int len_in_bytes)
{
    int port_id = (((intptr_t)port - (intptr_t)GPIOA) >> 10);
    RCC->APB2PCENR |= (RCC_APB2Periph_GPIOA << port_id); // Make sure port is enabled.

    int poffset  = (pin * 4);
    port->CFGLR  = (port->CFGLR & (~(0xf << poffset))) | ((GPIO_Speed_2MHz | GPIO_CNF_OUT_PP) << (poffset));

    int maskon   = 1 << pin;
    int maskoff  = 1 << (16 + pin);

    port->BSHR   = maskoff;

    uint8_t *end = data + len_in_bytes;
    while (data != end)
    {
        uint8_t byte = *data;

        int     i;
        for (i = 0; i < 8; i++)
        {
            if (byte & 0x80)
            {
                // WS2812B's need AT LEAST 625ns for a logical "1"
                port->BSHR = maskon;
                DelaySysTick(25);
                port->BSHR = maskoff;
                DelaySysTick(1);
            }
            else
            {
                // WS2812B's need BETWEEN 62.5 to about 500 ns for a logical "0"
#ifndef WS2812BSIMPLE_NO_IRQ_TWEAKING
                __disable_irq();
#endif
                port->BSHR = maskon;
                asm volatile("nop\nnop\nnop\nnop");
                port->BSHR = maskoff;
#ifndef WS2812BSIMPLE_NO_IRQ_TWEAKING
                __enable_irq();
#endif
                DelaySysTick(15);
            }
            byte <<= 1;
        }

        data++;
    }

    port->BSHR = maskoff;
}

#endif

#endif