/*-----------------------------------------------------------------------------------------------
  Arduino library to control SK6812 RGB Led strips using the Arduino STM32 LibMaple core
  -----------------------------------------------------------------------------------------------
 
  Note. 
  This library has only been tested on the SK6812 LED. It may not work with the older WS2812 or
  other types of addressable RGB LED, becuase it relies on a division multiple of the 72Mhz clock 
  frequence on the STM32 SPI to generate the correct width T0H pulse, of 400ns +/- 150nS
  SPI DIV32 gives a pulse width of 444nS which is well within spec for the SK6812 but
  is probably too long for the WS2812 which needs a 350ns pulse for T0H
 
  This WS2811B library is free software: you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as
  published by the Free Software Foundation, either version 3 of
  the License, or (at your option) any later version.

  It is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU Lesser General Public License for more details.

  See   <http://www.gnu.org/licenses/>.
  -----------------------------------------------------------------------------------------------*/

#include "SK6812.h"
#include "pins_arduino.h"
#include "wiring_private.h"
#include <SPI.h>


// Constructor when n is the number of LEDs in the strip
SK6812::SK6812(uint16_t number_of_leds) :
  brightness(0), pixels(NULL), doubleBuffer(NULL), begun(false)
{
  updateLength(number_of_leds);
}


SK6812::~SK6812() 
{
  if(pixels)   
  {
	  free(pixels);
  }
  SPI.end();
}

void SK6812::begin(void) {

if (!begun)
{
  SPI.setClockDivider(SPI_CLOCK_DIV4);// need bit rate of 400nS but closest we can do @ 72Mhz is 444ns (which is within spec)
  SPI.setBitOrder(LSBFIRST);
  SPI.begin();
  begun = true;
}
}

void SK6812::updateLength(uint16_t n)
{
  if(doubleBuffer) 
  {
	  free(doubleBuffer); 
  }

  numBytes = (n<<5) + n + 2; // 9 encoded bytes per pixel. 1 byte empty peamble to fix issue with SPI MOSI and on byte at the end to clear down MOSI 
							// Note. (n<<3) +n is a fast way of doing n*9
  if((doubleBuffer = (uint8_t *)malloc(numBytes*2)))
  {
    numLEDs = n;	 
	pixels = doubleBuffer;
	// Only need to init the part of the double buffer which will be interacted with by the API e.g. setPixelColor
	*pixels=0;//clear the preamble byte
	*(pixels+numBytes-1)=0;// clear the post send cleardown byte.
	clear();// Set the encoded data to all encoded zeros 
  } 
  else 
  {
    numLEDs = numBytes = 0;
  }
}

// Sends the current buffer to the leds
void SK6812::show(void) 
{
  SPI.dmaSendAsync(pixels,numBytes);// Start the DMA transfer of the current pixel buffer to the LEDs and return immediately.

  // Need to copy the last / current buffer to the other half of the double buffer as most API code does not rebuild the entire contents
  // from scratch. Often just a few pixels are changed e.g in a chaser effect
  
  if (pixels==doubleBuffer)
  {
	// pixels was using the first buffer
	pixels	= doubleBuffer+numBytes;  // set pixels to second buffer
	memcpy(pixels,doubleBuffer,numBytes);// copy first buffer to second buffer
  }
  else
  {
	// pixels was using the second buffer	  
	pixels	= doubleBuffer;  // set pixels to first buffer
	memcpy(pixels,doubleBuffer+numBytes,numBytes);	 // copy second buffer to first buffer 
  }	
}

/*Sets a specific pixel to a specific r,g,b colour 
* Because the pixels buffer contains the encoded bitstream, which is in triplets
* the lookup table need to be used to find the correct pattern for each byte in the 3 byte sequence.
*/
void SK6812::setPixelColor(uint16_t n, uint8_t r, uint8_t g, uint8_t b)
 {
   uint8_t *bptr = pixels + (n<<5) + n +1;
   
   //uint8_t *tPtr = (uint8_t *)encoderLookup + g*2 + g;// need to index 3 x g into the lookup
   uint8_t *tPtr = (uint8_t *)encoderLookup + g*11;// need to index 3 x g into the lookup
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;

   tPtr = (uint8_t *)encoderLookup + r*11;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   
   tPtr = (uint8_t *)encoderLookup + b*11;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
 }

void SK6812::setPixelColor(uint16_t n, uint32_t c)
  {
     uint8_t r,g,b;
   
    if(brightness) 
	{ 
      r = ((int)((uint8_t)(c >> 16)) * (int)brightness) >> 8;
      g = ((int)((uint8_t)(c >>  8)) * (int)brightness) >> 8;
      b = ((int)((uint8_t)c) * (int)brightness) >> 8;
	}
	else
	{
      r = (uint8_t)(c >> 16),
      g = (uint8_t)(c >>  8),
	  b = (uint8_t)c;		
	}
	
   uint8_t *bptr = pixels + (n<<5) + n +1;
   
   uint8_t *tPtr = (uint8_t *)encoderLookup + g*11;// need to index 3 x g into the lookup
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;

   tPtr = (uint8_t *)encoderLookup + r*11;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   
   tPtr = (uint8_t *)encoderLookup + b*11;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
   *bptr++ = *tPtr++;
}

// Convert separate R,G,B into packed 32-bit RGB color.
// Packed format is always RGB, regardless of LED strand color order.
uint32_t SK6812::Color(uint8_t r, uint8_t g, uint8_t b) {
  return ((uint32_t)r << 16) | ((uint32_t)g <<  8) | b;
}

// Convert separate R,G,B,W into packed 32-bit WRGB color.
// Packed format is always WRGB, regardless of LED strand color order.
uint32_t SK6812::Color(uint8_t r, uint8_t g, uint8_t b, uint8_t w) {
  return ((uint32_t)w << 24) | ((uint32_t)r << 16) | ((uint32_t)g <<  8) | b;
}


uint16_t SK6812::numPixels(void) const {
  return numLEDs;
}

// Adjust output brightness; 0=darkest (off), 255=brightest.  This does
// NOT immediately affect what's currently displayed on the LEDs.  The
// next call to show() will refresh the LEDs at this level.  However,
// this process is potentially "lossy," especially when increasing
// brightness.  The tight timing in the WS2811/WS2812 code means there
// aren't enough free cycles to perform this scaling on the fly as data
// is issued.  So we make a pass through the existing color data in RAM
// and scale it (subsequent graphics commands also work at this
// brightness level).  If there's a significant step up in brightness,
// the limited number of steps (quantization) in the old data will be
// quite visible in the re-scaled version.  For a non-destructive
// change, you'll need to re-render the full strip data.  C'est la vie.
void SK6812::setBrightness(uint8_t b) {
  // Stored brightness value is different than what's passed.
  // This simplifies the actual scaling math later, allowing a fast
  // 8x8-bit multiply and taking the MSB.  'brightness' is a uint8_t,
  // adding 1 here may (intentionally) roll over...so 0 = max brightness
  // (color values are interpreted literally; no scaling), 1 = min
  // brightness (off), 255 = just below max brightness.
  uint8_t newBrightness = b + 1;
  if(newBrightness != brightness) { // Compare against prior value
    // Brightness has changed -- re-scale existing data in RAM
    uint8_t  c,
            *ptr           = pixels,
             oldBrightness = brightness - 1; // De-wrap old brightness value
    uint16_t scale;
    if(oldBrightness == 0) scale = 0; // Avoid /0
    else if(b == 255) scale = 65535 / oldBrightness;
    else scale = (((uint16_t)newBrightness << 8) - 1) / oldBrightness;
    for(uint16_t i=0; i<numBytes; i++) 
	{
      c      = *ptr;
      *ptr++ = (c * scale) >> 8;
    }
    brightness = newBrightness;
  }
}

//Return the brightness value
uint8_t SK6812::getBrightness(void) const {
  return brightness - 1;
}

/*
*	Sets the encoded pixel data to turn all the LEDs off.
*/
void SK6812::clear() 
{
	uint8_t * bptr= pixels+1;// Note first byte in the buffer is a preable and is always zero. hence the +1
	uint8_t *tPtr;

	for(int i=0;i< (numLEDs *3);i++)
	{
	   tPtr = (uint8_t *)encoderLookup;
   	   *bptr++ = *tPtr++;
	   *bptr++ = *tPtr++;
	   *bptr++ = *tPtr++;	
	}
}