PianoLED-Circle-Edition/firmware/pianoleds.cpp

//
// pianoleds.cpp
//
#include "pianoleds.h"
#include <circle/util.h>
#include <assert.h>

// MIDI status nibbles
#define MIDI_NOTE_OFF		0x80
#define MIDI_NOTE_ON		0x90
#define MIDI_CONTROL_CHANGE	0xB0

// Control numbers that mean "stop everything"
#define MIDI_CC_ALL_SOUND_OFF	120
#define MIDI_CC_ALL_NOTES_OFF	123

CPianoLEDs::CPianoLEDs (void)
:	m_Stripe (WS2812B, LED_COUNT, 4000000, SPI_MASTER_DEVICE),
	m_bDirty (TRUE)
{
	memset ((void *) m_KeyVelocity, 0, sizeof m_KeyVelocity);
	memset ((void *) m_HintVelocity, 0, sizeof m_HintVelocity);
}

CPianoLEDs::~CPianoLEDs (void)
{
}

boolean CPianoLEDs::Initialize (void)
{
	if (!m_Stripe.Initialize ())
	{
		return FALSE;
	}

	// Start from a known-dark strip rather than whatever the pixels held
	// when power came up.
	return m_Stripe.Blackout ();
}

void CPianoLEDs::AttachMIDIDevice (CUSBMIDIDevice *pMIDIDevice)
{
	assert (pMIDIDevice != 0);

	// The gadget destroys and recreates its CUSBMIDIDevice across a suspend,
	// so any notes held at that moment would otherwise stay lit forever.
	AllOff ();

	pMIDIDevice->RegisterPacketHandler (MIDIPacketHandler, this);
}

void CPianoLEDs::MIDIPacketHandler (unsigned nCable, u8 *pPacket, unsigned nLength,
				    unsigned nDevice, void *pParam)
{
	CPianoLEDs *pThis = static_cast<CPianoLEDs *> (pParam);
	assert (pThis != 0);

	pThis->OnMIDIPacket (pPacket, nLength);
}

void CPianoLEDs::OnMIDIPacket (const u8 *pPacket, unsigned nLength)
{
	// Circle hands us one already-framed MIDI message of 1-3 bytes. Anything
	// shorter than a channel message cannot be a note event.
	if (nLength < 3)
	{
		return;
	}

	u8 ucStatus  = pPacket[0] & 0xF0;
	u8 ucChannel = pPacket[0] & 0x0F;

	switch (ucStatus)
	{
	case MIDI_NOTE_ON:
		// Note On with velocity 0 is the conventional Note Off.
		SetKey (pPacket[1], pPacket[2], ChannelMatches (ucChannel, HINT_MIDI_CHANNEL));
		break;

	case MIDI_NOTE_OFF:
		SetKey (pPacket[1], 0, ChannelMatches (ucChannel, HINT_MIDI_CHANNEL));
		break;

	case MIDI_CONTROL_CHANGE:
		if (   pPacket[1] == MIDI_CC_ALL_SOUND_OFF
		    || pPacket[1] == MIDI_CC_ALL_NOTES_OFF)
		{
			AllOff ();
		}
		break;

	default:
		break;
	}
}

void CPianoLEDs::SetKey (u8 ucNote, u8 ucVelocity, boolean bHint)
{
	// Drop anything off the ends of the keybed rather than trusting the
	// input; an out-of-range note would index past the strip.
	if (   ucNote < MIDI_NOTE_MIN
	    || ucNote > MIDI_NOTE_MAX)
	{
		return;
	}

	unsigned nKey = ucNote - MIDI_NOTE_MIN;

	if (bHint)
	{
		m_HintVelocity[nKey] = ucVelocity;
	}
	else
	{
		m_KeyVelocity[nKey] = ucVelocity;
	}

	m_bDirty = TRUE;
}

void CPianoLEDs::AllOff (void)
{
	memset ((void *) m_KeyVelocity, 0, sizeof m_KeyVelocity);
	memset ((void *) m_HintVelocity, 0, sizeof m_HintVelocity);

	m_bDirty = TRUE;
}

boolean CPianoLEDs::ChannelMatches (u8 ucChannel, u8 ucWanted)
{
	if (ucWanted == MIDI_CHANNEL_NONE)
	{
		return FALSE;
	}

	if (ucWanted == MIDI_CHANNEL_ANY)
	{
		return TRUE;
	}

	return ucChannel == ucWanted;
}

u8 CPianoLEDs::Scale (u8 ucChannel, u8 ucVelocity)
{
	unsigned nValue = ucChannel;

	// Global brightness ceiling. This is the clamp that keeps a whited-out
	// strip inside the supply's current budget; see config.h.
	nValue = nValue * GLOBAL_BRIGHTNESS / 255;

#if VELOCITY_SENSITIVE
	// Map velocity 1-127 onto [VELOCITY_FLOOR_PCT, 100] percent, so even the
	// softest note stays visible.
	unsigned nPercent =   VELOCITY_FLOOR_PCT
			    + (100 - VELOCITY_FLOOR_PCT) * ucVelocity / 127;
	nValue = nValue * nPercent / 100;
#endif

	return (u8) nValue;
}

void CPianoLEDs::Update (void)
{
	if (!m_bDirty)
	{
		return;
	}

	// Clear the flag before reading state, not after. An event arriving
	// mid-render then leaves the flag set and we render again next pass,
	// rather than being dropped.
	m_bDirty = FALSE;

	unsigned nLit = 0;

	for (unsigned nKey = 0; nKey < KEY_COUNT; nKey++)
	{
		u8 ucVelocity = m_KeyVelocity[nKey];
		boolean bHint = FALSE;

		if (ucVelocity == 0)
		{
			// A key being played wins over a "next note" hint on it.
			ucVelocity = m_HintVelocity[nKey];
			bHint = TRUE;
		}

		u8 ucRed = 0;
		u8 ucGreen = 0;
		u8 ucBlue = 0;

		// Bound the number of simultaneously lit keys, so no sequence of
		// MIDI events can drive the strip past the supply's budget.
		if (   ucVelocity != 0
		    && nLit < MAX_LIT_KEYS)
		{
			nLit++;

			if (bHint)
			{
				ucRed   = Scale (HINT_COLOR_R, ucVelocity);
				ucGreen = Scale (HINT_COLOR_G, ucVelocity);
				ucBlue  = Scale (HINT_COLOR_B, ucVelocity);
			}
			else
			{
				ucRed   = Scale (NOTE_COLOR_R, ucVelocity);
				ucGreen = Scale (NOTE_COLOR_G, ucVelocity);
				ucBlue  = Scale (NOTE_COLOR_B, ucVelocity);
			}
		}

#if STRIP_REVERSED
		unsigned nBase = (KEY_COUNT - 1 - nKey) * LEDS_PER_KEY;
#else
		unsigned nBase = nKey * LEDS_PER_KEY;
#endif

		for (unsigned i = 0; i < LEDS_PER_KEY; i++)
		{
			unsigned nLED = nBase + i;
			assert (nLED < LED_COUNT);

			m_Stripe.SetLED (nLED, ucRed, ucGreen, ucBlue);
		}
	}

	m_Stripe.Update ();
}