RFCOMM.c 6.85 KB
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/*
             LUFA Library
     Copyright (C) Dean Camera, 2010.
              
  dean [at] fourwalledcubicle [dot] com
      www.fourwalledcubicle.com
*/

/*
  Copyright 2010  Dean Camera (dean [at] fourwalledcubicle [dot] com)

  Permission to use, copy, modify, distribute, and sell this 
  software and its documentation for any purpose is hereby granted
  without fee, provided that the above copyright notice appear in 
  all copies and that both that the copyright notice and this
  permission notice and warranty disclaimer appear in supporting 
  documentation, and that the name of the author not be used in 
  advertising or publicity pertaining to distribution of the 
  software without specific, written prior permission.

  The author disclaim all warranties with regard to this
  software, including all implied warranties of merchantability
  and fitness.  In no event shall the author be liable for any
  special, indirect or consequential damages or any damages
  whatsoever resulting from loss of use, data or profits, whether
  in an action of contract, negligence or other tortious action,
  arising out of or in connection with the use or performance of
  this software.
*/

/** \file
 *
 *  RFCOMM layer module. This module manages the RFCOMM layer of the
 *  stack, providing virtual serial port channels on top of the lower
 *  L2CAP layer.
 */

#define  INCLUDE_FROM_RFCOMM_C
#include "RFCOMM.h"

/** 8-Bit CRC table used by the FCS field of each RFCOMM encoded frame, sourced from the ETSI TS 101 369 V7.2.0
 *  specification document, upon which the RFCOMM specification is based.
 */
const uint8_t CRC8_Table[256] PROGMEM =
	{
		0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75, 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
		0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69, 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
		0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D, 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
		0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51, 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
		0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05, 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
		0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19, 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
		0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D, 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
		0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21, 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
		0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95, 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
		0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89, 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
		0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD, 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
		0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1, 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
		0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5, 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
		0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9, 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
		0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD, 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
		0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1, 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
	};

/** Initializes the RFCOMM service, ready for new connections from a SDP client. */
void RFCOMM_Initialize(void)
{
	/* Not currently used */
}

void RFCOMM_ProcessPacket(void* Data, Bluetooth_Channel_t* const Channel)
{
	const RFCOMM_Header_t* FrameHeader = (const RFCOMM_Header_t*)Data;
	
	/* Decode the RFCOMM frame type from the header */
	switch (FrameHeader->Control & ~FRAME_POLL_FINAL)
	{
		case RFCOMM_Frame_SABM:
			RFCOMM_ProcessSABM(FrameHeader, Channel);
			break;
		case RFCOMM_Frame_UA:
			RFCOMM_ProcessUA(FrameHeader, Channel);
			break;
		case RFCOMM_Frame_DM:
			RFCOMM_ProcessDM(FrameHeader, Channel);
			break;
		case RFCOMM_Frame_DISC:
			RFCOMM_ProcessDISC(FrameHeader, Channel);
			break;
		case RFCOMM_Frame_UIH:
			RFCOMM_ProcessUIH(FrameHeader, Channel);
			break;
		default:
			BT_RFCOMM_DEBUG(1, "<< Unknown Frame Type");
			break;
	}
}

static void RFCOMM_ProcessSABM(const RFCOMM_Header_t* const FrameHeader, Bluetooth_Channel_t* const Channel)
{
	BT_RFCOMM_DEBUG(1, "<< SABM Received");
	BT_RFCOMM_DEBUG(2, "-- Address 0x%02X", FrameHeader->Address);
	
	// TODO: Reset channel send/receive state here
	
	struct
	{
		RFCOMM_Header_t FrameHeader;
		uint8_t         FrameLength;
		uint8_t         FCS;
	} ResponsePacket;
	
	/* Copy over the same frame header as the sent packet to copy the logical RFCOMM channel address */
	ResponsePacket.FrameHeader.Address              = FrameHeader->Address;
	
	/* Set the frame type to an Unnumbered Acknowledgement to acknowledge the SABM request */
	ResponsePacket.FrameHeader.Control = RFCOMM_Frame_UA;
	
	/* Set the length to 0 (LSB indicates end of 8-bit length field) */
	ResponsePacket.FrameLength = 0x01;
	
	/* Calculate the frame checksum from all fields except the FCS field itself */
	ResponsePacket.FCS = RFCOMM_GetFCSValue(&ResponsePacket, sizeof(ResponsePacket) - sizeof(ResponsePacket.FCS));
	
	BT_RFCOMM_DEBUG(1, ">> UA Sent");

	/* Send the completed response packet to the sender */
	Bluetooth_SendPacket(&ResponsePacket, sizeof(ResponsePacket), Channel);
}

static void RFCOMM_ProcessUA(const RFCOMM_Header_t* const FrameHeader, Bluetooth_Channel_t* const Channel)
{
	const uint8_t* CurrBufferPos = ((const uint8_t*)FrameHeader + sizeof(RFCOMM_Header_t));

	BT_RFCOMM_DEBUG(1, "<< UA Received");
	BT_RFCOMM_DEBUG(2, "-- Address 0x%02X", FrameHeader->Address);
}

static void RFCOMM_ProcessDM(const RFCOMM_Header_t* const FrameHeader, Bluetooth_Channel_t* const Channel)
{
	const uint8_t* CurrBufferPos = ((const uint8_t*)FrameHeader + sizeof(RFCOMM_Header_t));

	BT_RFCOMM_DEBUG(1, "<< DM Received");
	BT_RFCOMM_DEBUG(2, "-- Address 0x%02X", FrameHeader->Address);
}

static void RFCOMM_ProcessDISC(const RFCOMM_Header_t* const FrameHeader, Bluetooth_Channel_t* const Channel)
{
	const uint8_t* CurrBufferPos = ((const uint8_t*)FrameHeader + sizeof(RFCOMM_Header_t));

	BT_RFCOMM_DEBUG(1, "<< DISC Received");
	BT_RFCOMM_DEBUG(2, "-- Address 0x%02X", FrameHeader->Address);
}

static void RFCOMM_ProcessUIH(const RFCOMM_Header_t* const FrameHeader, Bluetooth_Channel_t* const Channel)
{
	const uint8_t* CurrBufferPos = ((const uint8_t*)FrameHeader + sizeof(RFCOMM_Header_t));

	BT_RFCOMM_DEBUG(1, "<< UIH Received");
	BT_RFCOMM_DEBUG(2, "-- Address 0x%02X", FrameHeader->Address);
}

static uint8_t RFCOMM_GetFCSValue(const void* FrameStart, uint16_t Length)
{
	const uint8_t* CurrPos = FrameStart;
	uint8_t        FCS     = 0xFF;
	
	while (Length--)
	  FCS = pgm_read_byte(CRC8_Table[FCS ^ *(CurrPos++)]);

	return ~FCS;
}

static uint16_t RFCOMM_GetFrameDataLength(const uint8_t** BufferPos)
{
	uint8_t FirstOctet  = *((*BufferPos)++);
	uint8_t SecondOctet = 0;
	
	if (!(FirstOctet & 0x01))
	  SecondOctet = *((*BufferPos)++);
	
	return (((uint16_t)SecondOctet << 7) | (FirstOctet >> 1));
}