freebsd-dev/sys/i4b/layer1/i4b_hdlc.h

/*
 * Copyright (c) 2000 Hans Petter Selasky. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *---------------------------------------------------------------------------
 *
 *	i4b_hdlc.h - software-HDLC header file
 *	--------------------------------------
 *
 *	$Id: i4b_hdlc.h,v 1.5 2000/08/28 07:41:19 hm Exp $
 *
 * $FreeBSD$
 *
 *	last edit-date: [Wed Jul 19 09:41:13 2000]
 *
 *---------------------------------------------------------------------------*/

#ifndef _I4B_HDLC_H_
#define _I4B_HDLC_H_

/*---------------------------------------------------------------------------*
 *	HDLC CRC table
 *
 * Usage:
 *	crc = (HDLC_FCS_TAB[(u_char)(crc ^ byte of data)] ^ (u_char)(crc >> 8));
 *
 *	For more information see RFC 1662 (p. 10)
 *---------------------------------------------------------------------------*/
const u_short HDLC_FCS_TAB[256] = { 0x0000, 
        0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf, 0x8c48, 
        0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7, 0x1081, 
        0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e, 0x9cc9, 
        0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876, 0x2102, 
        0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd, 0xad4a, 
        0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5, 0x3183, 
        0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c, 0xbdcb, 
        0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974, 0x4204, 
        0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb, 0xce4c, 
        0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3, 0x5285, 
        0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a, 0xdecd, 
        0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72, 0x6306, 
        0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9, 0xef4e, 
        0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1, 0x7387, 
        0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738, 0xffcf, 
        0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70, 0x8408, 
        0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7, 0x0840, 
        0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff, 0x9489, 
        0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036, 0x18c1, 
        0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e, 0xa50a, 
        0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5, 0x2942, 
        0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd, 0xb58b, 
        0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134, 0x39c3, 
        0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c, 0xc60c, 
        0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3, 0x4a44, 
        0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb, 0xd68d, 
        0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232, 0x5ac5, 
        0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a, 0xe70e, 
        0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1, 0x6b46, 
        0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9, 0xf78f, 
        0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330, 0x7bc7, 
        0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78 
};

/*---------------------------------------------------------------------------*
 *	HDLC bit table
 *	==============	
 *
 *	bits[0..3]:	A value which tells how many set bits there are at the
 *		   	beginning of the byte.
 *
 *	bits[4..7]:	Special bytes like 0x7e, 0x7d, 0xfd ... are flagged here
 *			NOTE: Special bytes also means 'abort' bytes (7 or more
 *			      continuous set bits)
 *
 *	bits[8..11]:	A copy of bits[0..3] but only incremented by one.
 *		     	NOTE: 0x7e has value '8' instead of '0'. Internal reasons.
 *
 *	bits[12..15]: 	A value which tells how many set bits there are at the
 *		      	end of the byte.
 *			NOTE: 0xff has both '8' incoming and '8' outgoing bits.
 *
 *---------------------------------------------------------------------------*/
const u_short HDLC_BIT_TAB[256] = { 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0403, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0504, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0403, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0605, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0403, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0504, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0403, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0160, 0x0706, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0403, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0504, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0403, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0605, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0403, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0504, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x0100, 0x0201, 0x0100, 0x0403, 0x0100, 
        0x0201, 0x0100, 0x0302, 0x01a0, 0x02a1, 0x0860, 0x0807, 0x1100, 
        0x1201, 0x1100, 0x1302, 0x1100, 0x1201, 0x1100, 0x1403, 0x1100, 
        0x1201, 0x1100, 0x1302, 0x1100, 0x1201, 0x1100, 0x1504, 0x1100, 
        0x1201, 0x1100, 0x1302, 0x1100, 0x1201, 0x1100, 0x1403, 0x1100, 
        0x1201, 0x1100, 0x1302, 0x1100, 0x1201, 0x1100, 0x1605, 0x1100, 
        0x1201, 0x1100, 0x1302, 0x1100, 0x1201, 0x1100, 0x1403, 0x1100, 
        0x1201, 0x1100, 0x1302, 0x1100, 0x1201, 0x1100, 0x1504, 0x1100, 
        0x1201, 0x1100, 0x1302, 0x1100, 0x1201, 0x1100, 0x1403, 0x1100, 
        0x1201, 0x1100, 0x1302, 0x1100, 0x1201, 0x1160, 0x1706, 0x2100, 
        0x2201, 0x2100, 0x2302, 0x2100, 0x2201, 0x2100, 0x2403, 0x2100, 
        0x2201, 0x2100, 0x2302, 0x2100, 0x2201, 0x2100, 0x2504, 0x2100, 
        0x2201, 0x2100, 0x2302, 0x2100, 0x2201, 0x2100, 0x2403, 0x2100, 
        0x2201, 0x2100, 0x2302, 0x2100, 0x2201, 0x2100, 0x2605, 0x3100, 
        0x3201, 0x3100, 0x3302, 0x3100, 0x3201, 0x3100, 0x3403, 0x3100, 
        0x3201, 0x3100, 0x3302, 0x3100, 0x3201, 0x3100, 0x3504, 0x4100, 
        0x4201, 0x4100, 0x4302, 0x4100, 0x4201, 0x4100, 0x4403, 0x5100, 
        0x5201, 0x5100, 0x5302, 0x6180, 0x6281, 0x7150, 0x8908 
};

/*---------------------------------------------------------------------------*
 *	HDLC_DECODE
 *	===========
 *
 *	u_char:  flag, blevel
 *	u_short: crc, ib, tmp, tmp2, len
 *
 *	next: 'continue' or 'goto xxx'
 *
 *	cfr: complete frame
 *	nfr: new frame
 *	     NOTE: must setup 'len' and 'dst', so that 'dst' may be written
 *		   at most 'len' times.
 *
 *	rab: abort
 *	rdd: read data (read byte is stored in 'tmp2')
 *	rdo: overflow
 *
 *	d: dummy
 *
 *	NOTE: setting flag to '0' and len to '0' => recover from rdu
 *	NOTE: bits[8 .. ] of tmp2 may be used to store custom data/flags
 *	NOTE: these variables have to be 'suspended' / 'resumed' somehow:
 *		flag, blevel, crc, ib, tmp, len
 *	NOTE: zero is default value for all variables.
 *	NOTE: each time 'dst' is written, 'len' is decreased by one.
 *---------------------------------------------------------------------------*/

#define HDLC_DECODE(dst, len, tmp, tmp2, blevel, ib, crc, flag,	rddcmd, nfrcmd,	\
		 cfrcmd, rabcmd, rdocmd, nextcmd, d) 				\
										\
	rddcmd;									\
										\
	ib  += HDLC_BIT_TAB[(u_char)tmp2];					\
										\
	if ((u_char)ib >= 5)							\
	{									\
		if (ib & 0x20)		/* de-stuff (msb) */			\
		{								\
			if ((u_char)tmp2 == 0x7e) goto j0##d;			\
			tmp2 += tmp2 & 0x7f;					\
			blevel--;						\
										\
			if ((ib += 0x100) & 0xc) tmp2 |= 1; /* */		\
		}								\
										\
		ib &= ~0xe0;							\
										\
		if ((u_char)ib == 6)	/* flag seq (lsb) */			\
		{								\
		 j0##d:	if (flag >= 2)						\
			{							\
				len += (4 - flag) & 3;	/* remove CRC bytes */	\
				crc ^= 0xf0b8;					\
				cfrcmd;						\
				len = 0;					\
			}							\
										\
			flag   = 1;						\
										\
			blevel = (ib >> 8) & 0xf;				\
			tmp    = ((u_char)tmp2) >> blevel;			\
			blevel = 8 - blevel;					\
										\
			ib >>= 12;						\
										\
			nextcmd;						\
		}								\
		if ((u_char)ib >= 7)	/* abort (msb & lsb) */			\
		{								\
			if (flag >= 2)						\
			{							\
				rabcmd;						\
				len = 0;					\
			}							\
										\
			flag = 0;						\
										\
			ib >>= 12;						\
										\
			nextcmd;						\
		}								\
		if ((u_char)ib == 5)	/* de-stuff (lsb) */			\
		{								\
			tmp2 = (tmp2 | (tmp2 + 1)) & ~0x1;			\
			blevel--;						\
		}								\
		if (blevel > 7)		/* EO - bits */				\
		{								\
			tmp |= (u_char)tmp2 >> (8 - (blevel &= 7));		\
										\
			ib >>= 12;						\
										\
			nextcmd;						\
		}								\
	}									\
										\
	tmp |= (u_char)tmp2 << blevel;						\
										\
	if (!len--)								\
	{									\
		len++;								\
										\
		if (!flag++) { flag--; goto j5##d;} /* hunt mode */		\
										\
		switch (flag)							\
		{   case 2: 		/* new frame */				\
			nfrcmd;							\
			crc = -1;						\
			if (!len--) { len++; flag++; goto j4##d; }		\
			goto j3##d;						\
		    case 3:		/* CRC (lsb's) */			\
		    case 4:		/* CRC (msb's) */			\
			goto j4##d;						\
		    case 5:		/* RDO */				\
			rdocmd;							\
			flag = 0;						\
			break;							\
		}								\
	}									\
	else									\
	{ 									\
	 j3##d:	dst = (u_char)tmp;						\
	 j4##d: crc = (HDLC_FCS_TAB[(u_char)(tmp ^ crc)] ^ (u_char)(crc >> 8));	\
	}									\
										\
 j5##d:	ib >>= 12;								\
	tmp >>= 8;								\

/*------ end of HDLC_DECODE -------------------------------------------------*/


/*---------------------------------------------------------------------------*
 *	HDLC_ENCODE
 *	===========
 *
 *	u_char:  flag, src
 *	u_short: tmp2, blevel, ib, crc, len
 *	u_int:   tmp
 *
 *	gfr: This is the place where you free the last [mbuf] chain, and get
 *	     the next one. If a mbuf is available the code should setup 'len'
 *	     and 'src' so that 'src' may be read 'len' times. If no mbuf is
 *	     available leave 'len' and 'src' untouched.
 *
 *	wrd: write data (output = (u_char)tmp)
 *
 *	d: dummy
 *
 *	NOTE: setting flag to '-2' and len to '0' => abort bytes will be sent
 *	NOTE: these variables have to be 'suspended' / 'resumed' somehow:
 *		flag, blevel, crc, ib, tmp, len
 *	NOTE: zero is default value for all variables.
 *	NOTE: each time 'src' is read, 'len' is decreased by one.
 *	NOTE: neither cmd's should exit through 'goto' or 'break' statements.
 *---------------------------------------------------------------------------*/

#define HDLC_ENCODE(src, len, tmp, tmp2, blevel, ib, crc, flag, gfrcmd, wrdcmd, d) \
										\
	if (blevel >= 0x800) { blevel -= 0x800; goto j4##d; }			\
										\
	if (!len--)								\
	{									\
		len++;								\
										\
		switch(++flag)							\
		{ default:			/* abort */			\
			tmp  = blevel = 0;	/* zero is default */		\
			tmp2 = 0xff;						\
			goto j3##d;						\
		  case 1:			/* 1st time FS */		\
		  case 2:			/* 2nd time FS */		\
			tmp2 = 0x7e;						\
			goto j3##d;						\
		  case 3:							\
			gfrcmd;			/* get new frame */		\
			if (!len--)						\
			{							\
				len++;						\
				flag--;		/* don't proceed */		\
				tmp2 = 0x7e;					\
				goto j3##d;	/* final FS */			\
			}							\
			else							\
			{							\
				crc = -1;					\
				ib  = 0;					\
				goto j1##d; 	/* first byte */		\
			}							\
		  case 4:							\
			crc ^= -1;						\
			tmp2 = (u_char)crc;					\
			goto j2##d;		/* CRC (lsb's) */		\
		  case 5:							\
			tmp2  = (u_char)(crc >> 8);				\
			flag  = 1;						\
			goto j2##d;		/* CRC (msb's) */		\
		}								\
	}									\
 	else									\
  	{ j1##d	:								\
		tmp2 = (u_char)src;						\
		crc =(HDLC_FCS_TAB[(u_char)(crc ^ tmp2)] ^ (u_char)(crc >> 8));	\
	  j2##d:								\
										\
		ib >>= 12;							\
		ib  += HDLC_BIT_TAB[(u_char)tmp2];				\
										\
		if ((u_char)ib >= 5)	/* stuffing */				\
		{								\
			blevel &= ~0xff;					\
										\
			if (ib & 0xc0)		/* bit stuff (msb) */		\
			{							\
				tmp2 += tmp2 & (0xff * (ib & 0xc0));		\
				ib %= 0x5000;					\
				blevel++;					\
			}							\
										\
			ib &= ~0xf0;						\
										\
			if ((u_char)ib >= 5)	/* bit stuff (lsb) */		\
			{							\
				tmp2 += tmp2 & ~0x1f >> ((ib - (ib >> 8) + 1)	\
								& 7);		\
				blevel++;					\
										\
				if ((u_char)ib >= 10)	/* bit stuff (msb) */	\
				{						\
					tmp2 += tmp2 & ~0x7ff >> ((ib - 	\
							(ib >> 8) + 1) & 7);	\
					blevel++;				\
				}						\
				if (ib & 0x8000)	/* bit walk */		\
				{						\
					ib = ((u_char)ib % 5) << 12;		\
				}						\
			}							\
										\
			tmp    |= tmp2 << (u_char)(blevel >> 8);		\
			blevel += (u_char)blevel << 8;				\
		}								\
		else		/* no stuffing */				\
		{								\
		  j3##d:tmp    |= tmp2 << (u_char)(blevel >> 8);		\
		}								\
	}									\
										\
 j4##d:	wrdcmd;									\
	tmp >>= 8;								\

/*------ end of HDLC_ENCODE -------------------------------------------------*/


#endif /* _I4B_HDLC_H_ */