/*- * 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_ */