MicroAPRS/Modem/protocol/mp1.c

#include "mp1.h"
#include "hardware.h"
#include "config.h"
#include <stdlib.h>			// Used for random
#include <string.h>
#include <drv/ser.h>
#include <drv/timer.h>		// Timer driver from BertOS

#include "compression/heatshrink_encoder.h"
#include "compression/heatshrink_decoder.h"

// We need an indicator to tell us whether we
// should send a parity byte. This happens
// whenever two normal bytes of data has been
// sent. We also keep the last sent byte in
// memory because we need it to calculate the
// parity byte.
static bool sendParityBlock = false;
static uint8_t lastByte = 0x00;

// We also need a buffer for compressing and
// decompressing packet data.
#if MP1_ENABLE_COMPRESSION
	static uint8_t compressionBuffer[MP1_MAX_DATA_SIZE];
#endif

#if SERIAL_DEBUG
// An int to hold amount of free RAM updated
// by the FREE_RAM function;
static int FREE_RAM;
#endif

// The GET_BIT macro is used in the interleaver
// and deinterleaver to access single bits of a
// byte.
INLINE bool GET_BIT(uint8_t byte, int n) { return (byte & (1 << (8-n))) == (1 << (8-n)); }

// This function calculates and returns a parity
// byte for two input bytes. The parity byte is
// used for correcting errors in the transmission.
// The error correction algorithm is a standard
// (12,8) Hamming code.
INLINE bool BIT(uint8_t byte, int n) { return ((byte & BV(n-1))>>(n-1)); }
static uint8_t mp1ParityBlock(uint8_t first, uint8_t other) {
	uint8_t parity = 0x00;

	parity = 	((BIT(first, 1) ^ BIT(first, 2) ^ BIT(first, 4) ^ BIT(first, 5) ^ BIT(first, 7))) +
				((BIT(first, 1) ^ BIT(first, 3) ^ BIT(first, 4) ^ BIT(first, 6) ^ BIT(first, 7))<<1) +
				((BIT(first, 2) ^ BIT(first, 3) ^ BIT(first, 4) ^ BIT(first, 8))<<2) +
				((BIT(first, 5) ^ BIT(first, 6) ^ BIT(first, 7) ^ BIT(first, 8))<<3) +

				((BIT(other, 1) ^ BIT(other, 2) ^ BIT(other, 4) ^ BIT(other, 5) ^ BIT(other, 7))<<4) +
				((BIT(other, 1) ^ BIT(other, 3) ^ BIT(other, 4) ^ BIT(other, 6) ^ BIT(other, 7))<<5) +
				((BIT(other, 2) ^ BIT(other, 3) ^ BIT(other, 4) ^ BIT(other, 8))<<6) +
				((BIT(other, 5) ^ BIT(other, 6) ^ BIT(other, 7) ^ BIT(other, 8))<<7);

	return parity;
}

// This decode function retrieves the buffer of
// received, deinterleaved and error-corrected
// bytes, inspects the header and determines
// whether there is padding to be removed, and
// whether the packet is compressed. If it is
// it is decompressed before being passed to
// the registered callback.
static void mp1Decode(MP1 *mp1) {
	MP1Packet packet;				// A decoded packet struct
	uint8_t *buffer	= mp1->buffer;	// Get the buffer from the protocol context
	
	// Get the header and "remove" it from the buffer
	uint8_t header = buffer[0];
	buffer++;

	// If header indicates a padded packet, remove
	// padding
	uint8_t padding = header >> 4;
	if (header & MP1_HEADER_PADDED) {
		for (int i = 0; i < padding; i++) {
			buffer++;
		}
	}

	if (SERIAL_DEBUG) kprintf("[TS=%d] ", mp1->packetLength);

	// Set the payload length of the packet to the counted
	// length minus 1, so we remove the checksum
	packet.dataLength = mp1->packetLength - 2 - (header & MP1_HEADER_PADDED)*padding;

	// Check if we have received a compressed packet
	if (MP1_ENABLE_COMPRESSION && (header & MP1_HEADER_COMPRESSION)) {
		// If we have, we decompress it and use the
		// decompressed data for the packet
		#if MP1_ENABLE_COMPRESSION
			if (SERIAL_DEBUG) kprintf("[CS=%d] ", packet.dataLength);
			size_t decompressedSize = decompress(buffer, packet.dataLength);
			if (SERIAL_DEBUG) kprintf("[DS=%d]", decompressedSize);
			packet.dataLength = decompressedSize;
			memcpy(mp1->buffer, compressionBuffer, decompressedSize);
		#endif
	} else {
		// If the packet was not compressed, we shift
		// the data in our buffer back down to the actual
		// beginning of the buffer array, since we incremented
		// the pointer address for removing the header and
		// padding.
		for (unsigned long i = 0; i < packet.dataLength; i++) {
			mp1->buffer[i] = buffer[i];
		}
	}

	// Set the data field of the packet to our buffer
	packet.data = mp1->buffer;

	// If a callback have been specified, let's
	// call it and pass the decoded packet
	if (mp1->callback) mp1->callback(&packet);
}


////////////////////////////////////////////////////////////
// The Poll function reads data from the modem, handles   //
// frame recognition and passes data on to higher layers  //
// if valid packets are found                             //
////////////////////////////////////////////////////////////
void mp1Poll(MP1 *mp1) {
	int byte; // A place to store our read byte

	// Read bytes from the modem until we reach EOF
	while ((byte = kfile_getc(mp1->modem)) != EOF) {
		// We read something from the modem, so we
		// set the settleTimer
		mp1->settleTimer = timer_clock();

		/////////////////////////////////////////////
		// This following block handles forward    //
		// error correction using an interleaved   //
		// (12,8) Hamming code                     //
		/////////////////////////////////////////////

		// If we have started reading (received an
		// HDLC_FLAG), we will start looking at the
		// incoming data and perform forward error
		// correction on it.
		

		if ((mp1->reading && (byte != AX25_ESC )) || (mp1->reading && (mp1->escape && (byte == AX25_ESC || byte == HDLC_FLAG || byte == HDLC_RESET)))) {
			// We have a byte, increment our read counter
			mp1->readLength++;

			// Check if we have read three bytes. If we
			// have, we should now have a block of two
			// data bytes and a parity byte. This block
			if (mp1->readLength % MP1_INTERLEAVE_SIZE == 0) {
				// If the last character in the block
				// looks like a control character, we
				// need to set the escape indicator to
				// false, since the next byte will be
				// read immediately after the FEC
				// routine, and thus, the normal reading
				// code will not reset the indicator.
				if (byte == AX25_ESC || byte == HDLC_FLAG || byte == HDLC_RESET) mp1->escape = false;
				
				// The block is interleaved, so we will
				// first put the received bytes in the
				// deinterleaving buffer
				for (int i = 1; i < MP1_INTERLEAVE_SIZE; i++) {
					mp1->interleaveIn[i-1] = mp1->buffer[mp1->packetLength-(MP1_INTERLEAVE_SIZE-i)];
				}
				mp1->interleaveIn[MP1_INTERLEAVE_SIZE-1] = byte;

				// We then deinterleave the block
				mp1Deinterleave(mp1);

				// Adjust the packet length, since we will get
				// parity bytes in the data buffer with block
				// sizes larger than 3
				mp1->packetLength -= MP1_INTERLEAVE_SIZE/3 - 1;

				// For each 3-byte block in the deinterleaved
				// bytes, we apply forward error correction
				for (int i = 0; i < MP1_INTERLEAVE_SIZE; i+=3) {
					// We now calculate a parity byte on the
					// received data.

					// Deinterleaved data bytes
					uint8_t a = mp1->interleaveIn[i];
					uint8_t b = mp1->interleaveIn[i+1];

					// Deinterleaved parity byte
					uint8_t p = mp1->interleaveIn[i+2];

					mp1->calculatedParity = mp1ParityBlock(a, b);

					// By XORing the calculated parity byte
					// with the received parity byte, we get
					// what is called the "syndrome". This
					// number will tell us if we had any
					// errors during transmission, and if so
					// where they are. Using Hamming code, we
					// can only detect single bit errors in a
					// byte though, which is why we interleave
					// the data, since most errors will usually
					// occur in bursts of more than one bit.
					// With 2 data byte interleaving we can
					// correct 2 consecutive bit errors.
					uint8_t syndrome = mp1->calculatedParity ^ p;
					if (syndrome == 0x00) {
						// If the syndrome equals 0, we either
						// don't have any errors, or the error
						// is unrecoverable, so we don't do
						// anything
					} else {
						// If the syndrome is not equal to 0,
						// there is a problem, and we will try
						// to correct it. We first need to split
						// the syndrome byte up into the two
						// actual syndrome numbers, one for
						// each data byte.
						uint8_t syndromes[2];
						syndromes[0] = syndrome & 0x0f;
						syndromes[1] = (syndrome & 0xf0) >> 4;

						// Then we look at each syndrome number
						// to determine what bit in the data
						// bytes to correct.
						for (int i = 0; i < 2; i++) {
							uint8_t s = syndromes[i];
							uint8_t correction = 0x00;
							if (s == 1 || s == 2 || s == 4 || s == 8) {
								// This signifies an error in the
								// parity block, so we actually
								// don't need any correction
								continue;
							}

							// The following determines what
							// bit to correct according to
							// the syndrome value.
							if (s == 3)  correction = 0x01;
							if (s == 5)  correction = 0x02;
							if (s == 6)  correction = 0x04;
							if (s == 7)  correction = 0x08;
							if (s == 9)  correction = 0x10;
							if (s == 10) correction = 0x20;
							if (s == 11) correction = 0x40;
							if (s == 12) correction = 0x80;

							// And finally we apply the correction
							if (i == 1) a ^= correction;
							if (i == 0) b ^= correction;

							// This is just for testing purposes.
							// Nice to know when corrections were
							// actually made.
							if (s != 0) mp1->correctionsMade += 1;
						}
					}

					// We now update the checksum of the packet
					// with the deinterleaved and possibly
					// corrected bytes.
					mp1->checksum_in ^= a;
					mp1->checksum_in ^= b;
					mp1->buffer[mp1->packetLength-(MP1_DATA_BLOCK_SIZE)+((i/3)*2)] = a;
					mp1->buffer[mp1->packetLength-(MP1_DATA_BLOCK_SIZE-1)+((i/3)*2)] = b;
				}

				continue;
			}
		}
		/////////////////////////////////////////////
		// End of forward error correction block   //
		/////////////////////////////////////////////
		
		// This next part of the poll function handles
		// the reading from the modem, and looks for
		// starts and ends of transmissions. It also
		// handles escape characters by discarding them
		// so they don't get put into the output data.

		// Let's first check if we have read an HDLC_FLAG.
		if (!mp1->escape && byte == HDLC_FLAG) {
			// We are not in an escape sequence and we
			// found a HDLC_FLAG. This can mean two things:
			if (mp1->readLength >= MP1_MIN_FRAME_LENGTH) {
				// We already have more data than the minimum
				// frame length, which means the flag signifies
				// the end of the packet. Pass control to the
				// decoder.
				//
				// We also set the settle timer to indicate
				// the time the frame completed reading.
				mp1->settleTimer = timer_clock();
				if ((mp1->checksum_in & 0xff) == 0x00) {
					if (SERIAL_DEBUG) kprintf("[CHK-OK] [C=%d] ", mp1->correctionsMade);
					mp1Decode(mp1);
				} else {
					// Checksum was incorrect, we don't do anything,
					// but you can enable the decode anyway, if you
					// need it for testing or debugging
					if (PASSALL) {
						if (SERIAL_DEBUG) kprintf("[CHK-ER] [C=%d] ", mp1->correctionsMade);
						mp1Decode(mp1);
					}
				}
			}
			// If the above is not the case, this must be the
			// beginning of a frame
			mp1->reading = true;
			mp1->packetLength = 0;
			mp1->readLength = 0;
			mp1->checksum_in = MP1_CHECKSUM_INIT;
			mp1->correctionsMade = 0;

			// We have indicated that we are reading,
			// and reset the length counter. Now we'll
			// continue to the next byte.
			continue;
		}

		if (!mp1->escape && byte == HDLC_RESET) {
			// Not good, we got a reset. The transmitting
			// party may have encountered an error. We'll
			// stop receiving this packet immediately.
			mp1->reading = false;
			continue;
		}

		if (!mp1->escape && byte == AX25_ESC) {
			// We found an escape character. We'll set
			// the escape seqeunce indicator so we don't
			// interpret the next byte as a reset or flag
			mp1->escape = true;

			// We then continue reading the next byte.
			continue;
		}

		// Now let's get to the actual reading of the data
		if (mp1->reading) {
			if (mp1->packetLength < MP1_MAX_FRAME_LENGTH + MP1_INTERLEAVE_SIZE) {
				// If the length of the current incoming frame is
				// still less than our max length, put the incoming
				// byte in the buffer. When we have collected 3
				// bytes, they will be processed by the error
				// correction part above.
				mp1->buffer[mp1->packetLength++] = byte;
			} else {
				// If not, we have a problem: The buffer has overrun
				// We need to stop receiving, and the packet will be
				// dropped :(
				mp1->reading = false;
			}
		}

		// We need to set the escape sequence indicator back
		// to false after each byte.
		mp1->escape = false;
	}

	if (kfile_error(mp1->modem)) {
		// If there was an error from the modem, we'll be rude
		// and just reset it. No error handling is done for now.
		kfile_clearerr(mp1->modem);
	}
}

// This is called to actually send the bytes
// after they have been interleaved
static void mp1WriteByte(MP1 *mp1, uint8_t byte) {
	// If we are sending something that looks
	// like an HDLC special byte, send an escape
	// character first
	if (byte == HDLC_FLAG ||
		byte == HDLC_RESET ||
		byte == AX25_ESC) {
		kfile_putc(AX25_ESC, mp1->modem);
	}
	kfile_putc(byte, mp1->modem);
}

// This is an intermediary function that
// receives outgoing bytes, and adds
// interleaving and a parity byte to the
// outgoing data in blocks of two data
// bytes. The actual transmitted block will
// be 3 bytes long due to the added parity
// byte.
static void mp1Putbyte(MP1 *mp1, uint8_t byte) {
	mp1Interleave(mp1, byte);

	if (sendParityBlock) {
		uint8_t p = mp1ParityBlock(lastByte, byte);
		mp1Interleave(mp1, p);
	}

	lastByte = byte;
	sendParityBlock ^= true;
}

// This function accepts a buffer with data
// to be transmitted, and structures it into
// a valid packet.
void mp1Send(MP1 *mp1, void *_buffer, size_t length) {
	// Reset our parity tx indicator
	sendParityBlock = false;

	// Open transmitter and wait for MP1_TXDELAY msecs
	AFSK_HW_PTT_ON();
	ticks_t start = timer_clock();
	#if MP1_USE_TX_QUEUE
	if (!mp1->queueProcessing) {
		while (timer_clock() - start < ms_to_ticks(MP1_TXDELAY)) {
			cpu_relax();
		}
	}
	#else
		while (timer_clock() - start < ms_to_ticks(MP1_TXDELAY)) {
			cpu_relax();
		}
	#endif


	// Get the transmit data buffer
	uint8_t *buffer = (uint8_t *)_buffer;

	// Initialize checksum to zero
	mp1->checksum_out = MP1_CHECKSUM_INIT;

	// We also reset the interleave counter to zero
	mp1->interleaveCounter = 0;

	// We start out assuming we should not use
	// compression.
	bool packetCompression = false;

	// We then try to compress the data to see
	// if we can save some space with compression.
	#if MP1_ENABLE_COMPRESSION
		size_t compressedSize = compress(buffer, length);
		if (compressedSize != 0 && compressedSize < length) {
			// Compression saved us some space, we'll
			// send the paket compressed
			packetCompression = true;
			// Write the compressed data into the
			// outgoing data buffer
			memcpy(buffer, compressionBuffer, compressedSize);
			
			// Make sure to set the length of the
			// data to the new (compressed) length
			length = compressedSize;
		} else {
			// We are not going to use compression,
			// so we don't do anything.
		}
	#endif

	// Transmit the HDLC_FLAG to signify start of TX
	kfile_putc(HDLC_FLAG, mp1->modem);
	
	// We now need to construct a header, that
	// can tell the receiving end whether the
	// packet is compressed. Since a packet must
	// have an even number of total payload bytes
	// (including the header), we check the length
	// of the outgoing data, and if it is not even,
	// we add a single byte of padding to the
	// packet. Remember that we also send a single
	// byte checksum at the end of the packet, so
	// the header and checksum bytes together don't
	// change whether the payload length is even
	// or not. The payload length needs to be even
	// since we are sending a parity byte for every
	// two data bytes sent, and because interleaving
	// happens in blocks of three bytes.
	uint8_t header = 0x00;

	// If we are using compression, set the
	// appropriate header flag to true.
	if (packetCompression) header ^= MP1_HEADER_COMPRESSION;

	// We check if the data length matches our
	// required block size
	uint8_t padding = (length+2) % MP1_DATA_BLOCK_SIZE;

	if (padding != 0) {
		// If it does not, we set the appropriate
		// header flag to indicate that we are
		// padding this packet.
		header ^= MP1_HEADER_PADDED;

		// And calculate how much padding we need
		padding = MP1_DATA_BLOCK_SIZE - padding;

		// And put the amount of padding we are
		// going to append in the header
		header ^= (padding << 4);

		// We then update the checksum with the
		// header byte and queue it for transmit
		mp1->checksum_out = mp1->checksum_out ^ header;
		mp1Putbyte(mp1, header);

		// We now update the checksum with the
		// padding bytes, and queue these for
		// transmission as well.
		for (int i = 0; i < padding; i++) {
			mp1->checksum_out = mp1->checksum_out ^ MP1_PADDING;
			mp1Putbyte(mp1, MP1_PADDING);
		}
	} else {
		// If the length already matches, we
		// just update the checksum with the
		// header byte and queue it.
		mp1->checksum_out = mp1->checksum_out ^ header;
		mp1Putbyte(mp1, header);
	}

	// Now we'll transmit the actual data of
	// the packet. We continously increment the
	// pointer address of the buffer while
	// passing it to the intermediary output
	// function. Everytime the interleaving
	// counter reaches 3, a block will be
	// transmitted.
	while (length--) {
		mp1->checksum_out = mp1->checksum_out ^ *buffer;
		mp1Putbyte(mp1, *buffer++);
	}

	// Finally we write the checksum to the
	// end of the packet.
	mp1Putbyte(mp1, mp1->checksum_out);

	// And transmit a HDLC_FLAG to signify
	// end of the transmission.
	kfile_putc(HDLC_FLAG, mp1->modem);

	// Turn off manual PTT
	#if MP1_USE_TX_QUEUE
		if (!mp1->queueProcessing) AFSK_HW_PTT_OFF();
	#else
		AFSK_HW_PTT_OFF();
	#endif
}

// This function accepts a frame and stores
// it in the transmission queue
#if MP1_USE_TX_QUEUE
	void mp1QueueFrame(MP1 *mp1, void *_buffer, size_t length) {
		if (mp1->queueLength < MP1_TX_QUEUE_LENGTH) {
			uint8_t *buffer = (uint8_t *)_buffer;
			mp1->frameLengths[mp1->queueLength] = length;
			memcpy(mp1->frameQueue[mp1->queueLength++], buffer, length);
		}
	}
#endif

// This function processes the transmission
// queue.
#if MP1_USE_TX_QUEUE
	void mp1ProcessQueue(MP1 *mp1) {
		int i = 0;
		while (mp1->queueLength) {
			mp1Send(mp1, mp1->frameQueue[i], mp1->frameLengths[i]);
			i++;
			mp1->queueLength--;
		}
		AFSK_HW_PTT_OFF();
	}
#endif

// A simple form of P-persistent CSMA.
// Everytime we have heard activity
// on the channel, we wait at least
// MP1_SETTLE_TIME milliseconds after the
// activity has ceased. We then pick a random
// number, and if it is less than
// MP1_P_PERSISTENCE, we transmit.
bool mp1CarrierSense(MP1 *mp1) {
	if (MP1_ENABLE_CSMA) {
		if (mp1->randomSeed == 0) {
			mp1->randomSeed = timer_clock();
			srand(mp1->randomSeed);
		}

		if (timer_clock() - mp1->settleTimer > ms_to_ticks(MP1_SETTLE_TIME)) {
			uint8_t r = rand() % 255;
			if (r < MP1_P_PERSISTENCE) {
				return false;
			} else {
				mp1->settleTimer = timer_clock() - MP1_SETTLE_TIME + MP1_SLOT_TIME;
				return true;
			}
		} else {
			return true;
		}
	} else {
		return false;
	}
}

// This function will simply initialize
// the protocol context and allocate the
// needed memory.
void mp1Init(MP1 *mp1, KFile *modem, mp1_callback_t callback) {
	// Allocate memory for our protocol "object"
	memset(mp1, 0, sizeof(*mp1));
	// Set references to our modem "object" and
	// a callback for when a packet has been decoded
	mp1->modem = modem;
	mp1->callback = callback;
	mp1->settleTimer = timer_clock();
	mp1->randomSeed = 0;
	#if MP1_USE_TX_QUEUE
		mp1->queueLength = 0;
		mp1->queueProcessing = false;
	#endif
}

// A handy debug function that can determine
// how much available memory we have left.
#if SERIAL_DEBUG
int freeRam(void) {
   extern int __heap_start, *__brkval; 
   int v;
   FREE_RAM = (int) &v - (__brkval == 0 ? (int) &__heap_start : (int) __brkval);
   return FREE_RAM; 
}
#endif

// This function compresses data using
// the Heatshrink library
#if MP1_ENABLE_COMPRESSION
size_t compress(uint8_t *input, size_t length) {
	heatshrink_encoder *hse = heatshrink_encoder_alloc(8, 4);
	if (hse == NULL) {
		if (SERIAL_DEBUG) kprintf("Could not allocate compressor\n");
		return 0;
	}

	size_t written = 0;
	size_t sunk = 0;
	heatshrink_encoder_sink(hse, input, length, &sunk);
	int status = heatshrink_encoder_finish(hse);

	if (sunk < length) {
		heatshrink_encoder_free(hse);
		return 0;
	} else {
		if (status == HSER_FINISH_MORE) {
			heatshrink_encoder_poll(hse, compressionBuffer, MP1_MAX_FRAME_LENGTH, &written);
		}
	}

	heatshrink_encoder_free(hse);
	return written;
}
#endif

// This function decompresses data using
// the Heatshrink library
#if MP1_ENABLE_COMPRESSION
size_t decompress(uint8_t *input, size_t length) {
	heatshrink_decoder *hsd = heatshrink_decoder_alloc(MP1_MAX_FRAME_LENGTH, 8, 4);
	if (hsd == NULL) {
		if (SERIAL_DEBUG) kprintf("Could not allocate decompressor\n");
		return 0;
	}

	size_t written = 0;
	size_t sunk = 0;
	heatshrink_decoder_sink(hsd, input, length, &sunk);
	int status = heatshrink_decoder_finish(hsd);

	if (sunk < length) {
		heatshrink_decoder_free(hsd);
		return 0;
	} else {
		if (status == HSER_FINISH_MORE) {
			heatshrink_decoder_poll(hsd, compressionBuffer, MP1_MAX_FRAME_LENGTH, &written);
		}
	}

	heatshrink_decoder_free(hsd);
	return written;
}
#endif


// Following is the functions responsible
// for interleaving and deinterleaving
// blocks of data. The interleaving table
// for 3-byte interleaving is also included.
// The table for 12-byte is much simpler,
// and should be inferable from looking
// at the function.

///////////////////////////////
// Interleave-table (3-byte) //
///////////////////////////////
//
// Non-interleaved:
// aaaaaaaa bbbbbbbb cccccccc
// 12345678 12345678 12345678
// M      L
// S      S
// B      B
//
// Interleaved:
// abcabcab cabcabca bcabcabc
// 11144477 22255578 63336688
//
///////////////////////////////

void mp1Interleave(MP1 *mp1, uint8_t byte) {
	mp1->interleaveOut[mp1->interleaveCounter] = byte;
	mp1->interleaveCounter++;
	if (mp1->interleaveCounter == MP1_INTERLEAVE_SIZE) {
		// We have the bytes we need for interleaving
		// in the buffer and are ready to interleave them.
		#if MP1_INTERLEAVE_SIZE == 3
			// This is for 3-byte interleaving
			uint8_t a = (GET_BIT(mp1->interleaveOut[0], 1) << 7) +
						(GET_BIT(mp1->interleaveOut[1], 1) << 6) +
						(GET_BIT(mp1->interleaveOut[2], 1) << 5) +
						(GET_BIT(mp1->interleaveOut[0], 4) << 4) +
						(GET_BIT(mp1->interleaveOut[1], 4) << 3) +
						(GET_BIT(mp1->interleaveOut[2], 4) << 2) +
						(GET_BIT(mp1->interleaveOut[0], 7) << 1) +
						(GET_BIT(mp1->interleaveOut[1], 7));
			mp1WriteByte(mp1, a);

			uint8_t b = (GET_BIT(mp1->interleaveOut[2], 2) << 7) +
						(GET_BIT(mp1->interleaveOut[0], 2) << 6) +
						(GET_BIT(mp1->interleaveOut[1], 2) << 5) +
						(GET_BIT(mp1->interleaveOut[2], 5) << 4) +
						(GET_BIT(mp1->interleaveOut[0], 5) << 3) +
						(GET_BIT(mp1->interleaveOut[1], 5) << 2) +
						(GET_BIT(mp1->interleaveOut[2], 7) << 1) +
						(GET_BIT(mp1->interleaveOut[0], 8));
			mp1WriteByte(mp1, b);

			uint8_t c = (GET_BIT(mp1->interleaveOut[1], 6) << 7) +
						(GET_BIT(mp1->interleaveOut[2], 3) << 6) +
						(GET_BIT(mp1->interleaveOut[0], 3) << 5) +
						(GET_BIT(mp1->interleaveOut[1], 3) << 4) +
						(GET_BIT(mp1->interleaveOut[2], 6) << 3) +
						(GET_BIT(mp1->interleaveOut[0], 6) << 2) +
						(GET_BIT(mp1->interleaveOut[1], 8) << 1) +
						(GET_BIT(mp1->interleaveOut[2], 8));

			mp1WriteByte(mp1, c);
		#elif MP1_INTERLEAVE_SIZE == 12
			// This is for 12-byte interleaving
			uint8_t a = (GET_BIT(mp1->interleaveOut[0], 1) << 7) +
						(GET_BIT(mp1->interleaveOut[1], 1) << 6) +
						(GET_BIT(mp1->interleaveOut[3], 1) << 5) +
						(GET_BIT(mp1->interleaveOut[4], 1) << 4) +
						(GET_BIT(mp1->interleaveOut[6], 1) << 3) +
						(GET_BIT(mp1->interleaveOut[7], 1) << 2) +
						(GET_BIT(mp1->interleaveOut[9], 1) << 1) +
						(GET_BIT(mp1->interleaveOut[10],1));
			mp1WriteByte(mp1, a);

			uint8_t b = (GET_BIT(mp1->interleaveOut[0], 2) << 7) +
						(GET_BIT(mp1->interleaveOut[1], 2) << 6) +
						(GET_BIT(mp1->interleaveOut[3], 2) << 5) +
						(GET_BIT(mp1->interleaveOut[4], 2) << 4) +
						(GET_BIT(mp1->interleaveOut[6], 2) << 3) +
						(GET_BIT(mp1->interleaveOut[7], 2) << 2) +
						(GET_BIT(mp1->interleaveOut[9], 2) << 1) +
						(GET_BIT(mp1->interleaveOut[10],2));
			mp1WriteByte(mp1, b);

			uint8_t c = (GET_BIT(mp1->interleaveOut[0], 3) << 7) +
						(GET_BIT(mp1->interleaveOut[1], 3) << 6) +
						(GET_BIT(mp1->interleaveOut[3], 3) << 5) +
						(GET_BIT(mp1->interleaveOut[4], 3) << 4) +
						(GET_BIT(mp1->interleaveOut[6], 3) << 3) +
						(GET_BIT(mp1->interleaveOut[7], 3) << 2) +
						(GET_BIT(mp1->interleaveOut[9], 3) << 1) +
						(GET_BIT(mp1->interleaveOut[10],3));
			mp1WriteByte(mp1, c);

			uint8_t d = (GET_BIT(mp1->interleaveOut[0], 4) << 7) +
						(GET_BIT(mp1->interleaveOut[1], 4) << 6) +
						(GET_BIT(mp1->interleaveOut[3], 4) << 5) +
						(GET_BIT(mp1->interleaveOut[4], 4) << 4) +
						(GET_BIT(mp1->interleaveOut[6], 4) << 3) +
						(GET_BIT(mp1->interleaveOut[7], 4) << 2) +
						(GET_BIT(mp1->interleaveOut[9], 4) << 1) +
						(GET_BIT(mp1->interleaveOut[10],4));
			mp1WriteByte(mp1, d);

			uint8_t e = (GET_BIT(mp1->interleaveOut[0], 5) << 7) +
						(GET_BIT(mp1->interleaveOut[1], 5) << 6) +
						(GET_BIT(mp1->interleaveOut[3], 5) << 5) +
						(GET_BIT(mp1->interleaveOut[4], 5) << 4) +
						(GET_BIT(mp1->interleaveOut[6], 5) << 3) +
						(GET_BIT(mp1->interleaveOut[7], 5) << 2) +
						(GET_BIT(mp1->interleaveOut[9], 5) << 1) +
						(GET_BIT(mp1->interleaveOut[10],5));
			mp1WriteByte(mp1, e);

			uint8_t f = (GET_BIT(mp1->interleaveOut[0], 6) << 7) +
						(GET_BIT(mp1->interleaveOut[1], 6) << 6) +
						(GET_BIT(mp1->interleaveOut[3], 6) << 5) +
						(GET_BIT(mp1->interleaveOut[4], 6) << 4) +
						(GET_BIT(mp1->interleaveOut[6], 6) << 3) +
						(GET_BIT(mp1->interleaveOut[7], 6) << 2) +
						(GET_BIT(mp1->interleaveOut[9], 6) << 1) +
						(GET_BIT(mp1->interleaveOut[10],6));
			mp1WriteByte(mp1, f);

			uint8_t g = (GET_BIT(mp1->interleaveOut[0], 7) << 7) +
						(GET_BIT(mp1->interleaveOut[1], 7) << 6) +
						(GET_BIT(mp1->interleaveOut[3], 7) << 5) +
						(GET_BIT(mp1->interleaveOut[4], 7) << 4) +
						(GET_BIT(mp1->interleaveOut[6], 7) << 3) +
						(GET_BIT(mp1->interleaveOut[7], 7) << 2) +
						(GET_BIT(mp1->interleaveOut[9], 7) << 1) +
						(GET_BIT(mp1->interleaveOut[10],7));
			mp1WriteByte(mp1, g);

			uint8_t h = (GET_BIT(mp1->interleaveOut[0], 8) << 7) +
						(GET_BIT(mp1->interleaveOut[1], 8) << 6) +
						(GET_BIT(mp1->interleaveOut[3], 8) << 5) +
						(GET_BIT(mp1->interleaveOut[4], 8) << 4) +
						(GET_BIT(mp1->interleaveOut[6], 8) << 3) +
						(GET_BIT(mp1->interleaveOut[7], 8) << 2) +
						(GET_BIT(mp1->interleaveOut[9], 8) << 1) +
						(GET_BIT(mp1->interleaveOut[10],8));
			mp1WriteByte(mp1, h);

			uint8_t p = (GET_BIT(mp1->interleaveOut[2], 1) << 7) +
						(GET_BIT(mp1->interleaveOut[2], 5) << 6) +
						(GET_BIT(mp1->interleaveOut[5], 1) << 5) +
						(GET_BIT(mp1->interleaveOut[5], 5) << 4) +
						(GET_BIT(mp1->interleaveOut[8], 1) << 3) +
						(GET_BIT(mp1->interleaveOut[8], 5) << 2) +
						(GET_BIT(mp1->interleaveOut[11],1) << 1) +
						(GET_BIT(mp1->interleaveOut[11],5));
			mp1WriteByte(mp1, p);

			uint8_t q = (GET_BIT(mp1->interleaveOut[2], 2) << 7) +
						(GET_BIT(mp1->interleaveOut[2], 6) << 6) +
						(GET_BIT(mp1->interleaveOut[5], 2) << 5) +
						(GET_BIT(mp1->interleaveOut[5], 6) << 4) +
						(GET_BIT(mp1->interleaveOut[8], 2) << 3) +
						(GET_BIT(mp1->interleaveOut[8], 6) << 2) +
						(GET_BIT(mp1->interleaveOut[11],2) << 1) +
						(GET_BIT(mp1->interleaveOut[11],6));
			mp1WriteByte(mp1, q);

			uint8_t s = (GET_BIT(mp1->interleaveOut[2], 3) << 7) +
						(GET_BIT(mp1->interleaveOut[2], 7) << 6) +
						(GET_BIT(mp1->interleaveOut[5], 3) << 5) +
						(GET_BIT(mp1->interleaveOut[5], 7) << 4) +
						(GET_BIT(mp1->interleaveOut[8], 3) << 3) +
						(GET_BIT(mp1->interleaveOut[8], 7) << 2) +
						(GET_BIT(mp1->interleaveOut[11],3) << 1) +
						(GET_BIT(mp1->interleaveOut[11],7));
			mp1WriteByte(mp1, s);

			uint8_t t = (GET_BIT(mp1->interleaveOut[2], 4) << 7) +
						(GET_BIT(mp1->interleaveOut[2], 8) << 6) +
						(GET_BIT(mp1->interleaveOut[5], 4) << 5) +
						(GET_BIT(mp1->interleaveOut[5], 8) << 4) +
						(GET_BIT(mp1->interleaveOut[8], 4) << 3) +
						(GET_BIT(mp1->interleaveOut[8], 8) << 2) +
						(GET_BIT(mp1->interleaveOut[11],4) << 1) +
						(GET_BIT(mp1->interleaveOut[11],8));
			mp1WriteByte(mp1, t);

		#endif

		mp1->interleaveCounter = 0;
	}
}


void mp1Deinterleave(MP1 *mp1) {
	#if MP1_INTERLEAVE_SIZE == 3
		uint8_t a = (GET_BIT(mp1->interleaveIn[0], 1) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 2) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 3) << 5) +
					(GET_BIT(mp1->interleaveIn[0], 4) << 4) +
					(GET_BIT(mp1->interleaveIn[1], 5) << 3) +
					(GET_BIT(mp1->interleaveIn[2], 6) << 2) +
					(GET_BIT(mp1->interleaveIn[0], 7) << 1) +
					(GET_BIT(mp1->interleaveIn[1], 8));

		uint8_t b = (GET_BIT(mp1->interleaveIn[0], 2) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 3) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 4) << 5) +
					(GET_BIT(mp1->interleaveIn[0], 5) << 4) +
					(GET_BIT(mp1->interleaveIn[1], 6) << 3) +
					(GET_BIT(mp1->interleaveIn[2], 1) << 2) +
					(GET_BIT(mp1->interleaveIn[0], 8) << 1) +
					(GET_BIT(mp1->interleaveIn[2], 7));

		uint8_t c = (GET_BIT(mp1->interleaveIn[0], 3) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 1) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 2) << 5) +
					(GET_BIT(mp1->interleaveIn[0], 6) << 4) +
					(GET_BIT(mp1->interleaveIn[1], 4) << 3) +
					(GET_BIT(mp1->interleaveIn[2], 5) << 2) +
					(GET_BIT(mp1->interleaveIn[1], 7) << 1) +
					(GET_BIT(mp1->interleaveIn[2], 8));

		mp1->interleaveIn[0] = a;
		mp1->interleaveIn[1] = b;
		mp1->interleaveIn[2] = c;
	#elif MP1_INTERLEAVE_SIZE == 12
		uint8_t a = (GET_BIT(mp1->interleaveIn[0], 1) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 1) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 1) << 5) +
					(GET_BIT(mp1->interleaveIn[3], 1) << 4) +
					(GET_BIT(mp1->interleaveIn[4], 1) << 3) +
					(GET_BIT(mp1->interleaveIn[5], 1) << 2) +
					(GET_BIT(mp1->interleaveIn[6], 1) << 1) +
					(GET_BIT(mp1->interleaveIn[7], 1));

		uint8_t b = (GET_BIT(mp1->interleaveIn[0], 2) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 2) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 2) << 5) +
					(GET_BIT(mp1->interleaveIn[3], 2) << 4) +
					(GET_BIT(mp1->interleaveIn[4], 2) << 3) +
					(GET_BIT(mp1->interleaveIn[5], 2) << 2) +
					(GET_BIT(mp1->interleaveIn[6], 2) << 1) +
					(GET_BIT(mp1->interleaveIn[7], 2));

		uint8_t p = (GET_BIT(mp1->interleaveIn[8], 1) << 7) +
					(GET_BIT(mp1->interleaveIn[9], 1) << 6) +
					(GET_BIT(mp1->interleaveIn[10],1) << 5) +
					(GET_BIT(mp1->interleaveIn[11],1) << 4) +
					(GET_BIT(mp1->interleaveIn[8], 2) << 3) +
					(GET_BIT(mp1->interleaveIn[9], 2) << 2) +
					(GET_BIT(mp1->interleaveIn[10],2) << 1) +
					(GET_BIT(mp1->interleaveIn[11],2));

		uint8_t c = (GET_BIT(mp1->interleaveIn[0], 3) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 3) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 3) << 5) +
					(GET_BIT(mp1->interleaveIn[3], 3) << 4) +
					(GET_BIT(mp1->interleaveIn[4], 3) << 3) +
					(GET_BIT(mp1->interleaveIn[5], 3) << 2) +
					(GET_BIT(mp1->interleaveIn[6], 3) << 1) +
					(GET_BIT(mp1->interleaveIn[7], 3));

		uint8_t d = (GET_BIT(mp1->interleaveIn[0], 4) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 4) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 4) << 5) +
					(GET_BIT(mp1->interleaveIn[3], 4) << 4) +
					(GET_BIT(mp1->interleaveIn[4], 4) << 3) +
					(GET_BIT(mp1->interleaveIn[5], 4) << 2) +
					(GET_BIT(mp1->interleaveIn[6], 4) << 1) +
					(GET_BIT(mp1->interleaveIn[7], 4));

		uint8_t q = (GET_BIT(mp1->interleaveIn[8], 3) << 7) +
					(GET_BIT(mp1->interleaveIn[9], 3) << 6) +
					(GET_BIT(mp1->interleaveIn[10],3) << 5) +
					(GET_BIT(mp1->interleaveIn[11],3) << 4) +
					(GET_BIT(mp1->interleaveIn[8], 4) << 3) +
					(GET_BIT(mp1->interleaveIn[9], 4) << 2) +
					(GET_BIT(mp1->interleaveIn[10],4) << 1) +
					(GET_BIT(mp1->interleaveIn[11],4));

		uint8_t e = (GET_BIT(mp1->interleaveIn[0], 5) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 5) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 5) << 5) +
					(GET_BIT(mp1->interleaveIn[3], 5) << 4) +
					(GET_BIT(mp1->interleaveIn[4], 5) << 3) +
					(GET_BIT(mp1->interleaveIn[5], 5) << 2) +
					(GET_BIT(mp1->interleaveIn[6], 5) << 1) +
					(GET_BIT(mp1->interleaveIn[7], 5));

		uint8_t f = (GET_BIT(mp1->interleaveIn[0], 6) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 6) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 6) << 5) +
					(GET_BIT(mp1->interleaveIn[3], 6) << 4) +
					(GET_BIT(mp1->interleaveIn[4], 6) << 3) +
					(GET_BIT(mp1->interleaveIn[5], 6) << 2) +
					(GET_BIT(mp1->interleaveIn[6], 6) << 1) +
					(GET_BIT(mp1->interleaveIn[7], 6));

		uint8_t s = (GET_BIT(mp1->interleaveIn[8], 5) << 7) +
					(GET_BIT(mp1->interleaveIn[9], 5) << 6) +
					(GET_BIT(mp1->interleaveIn[10],5) << 5) +
					(GET_BIT(mp1->interleaveIn[11],5) << 4) +
					(GET_BIT(mp1->interleaveIn[8], 6) << 3) +
					(GET_BIT(mp1->interleaveIn[9], 6) << 2) +
					(GET_BIT(mp1->interleaveIn[10],6) << 1) +
					(GET_BIT(mp1->interleaveIn[11],6));

		uint8_t g = (GET_BIT(mp1->interleaveIn[0], 7) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 7) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 7) << 5) +
					(GET_BIT(mp1->interleaveIn[3], 7) << 4) +
					(GET_BIT(mp1->interleaveIn[4], 7) << 3) +
					(GET_BIT(mp1->interleaveIn[5], 7) << 2) +
					(GET_BIT(mp1->interleaveIn[6], 7) << 1) +
					(GET_BIT(mp1->interleaveIn[7], 7));

		uint8_t h = (GET_BIT(mp1->interleaveIn[0], 8) << 7) +
					(GET_BIT(mp1->interleaveIn[1], 8) << 6) +
					(GET_BIT(mp1->interleaveIn[2], 8) << 5) +
					(GET_BIT(mp1->interleaveIn[3], 8) << 4) +
					(GET_BIT(mp1->interleaveIn[4], 8) << 3) +
					(GET_BIT(mp1->interleaveIn[5], 8) << 2) +
					(GET_BIT(mp1->interleaveIn[6], 8) << 1) +
					(GET_BIT(mp1->interleaveIn[7], 8));

		uint8_t t = (GET_BIT(mp1->interleaveIn[8], 7) << 7) +
					(GET_BIT(mp1->interleaveIn[9], 7) << 6) +
					(GET_BIT(mp1->interleaveIn[10],7) << 5) +
					(GET_BIT(mp1->interleaveIn[11],7) << 4) +
					(GET_BIT(mp1->interleaveIn[8], 8) << 3) +
					(GET_BIT(mp1->interleaveIn[9], 8) << 2) +
					(GET_BIT(mp1->interleaveIn[10],8) << 1) +
					(GET_BIT(mp1->interleaveIn[11],8));

		mp1->interleaveIn[0] =  a;
		mp1->interleaveIn[1] =  b;
		mp1->interleaveIn[2] =  p;
		mp1->interleaveIn[3] =  c;
		mp1->interleaveIn[4] =  d;
		mp1->interleaveIn[5] =  q;
		mp1->interleaveIn[6] =  e;
		mp1->interleaveIn[7] =  f;
		mp1->interleaveIn[8] =  s;
		mp1->interleaveIn[9] =  g;
		mp1->interleaveIn[10] = h;
		mp1->interleaveIn[11] = t;

	#endif
}