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freebsd/sys/i4b/layer1/i4b_hdlc.h

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/*-
* 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_
extern const u_short HDLC_FCS_TAB[256];
extern const u_short HDLC_BIT_TAB[256];
/*---------------------------------------------------------------------------*
* 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_ */
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