/* 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