isdnhdlc.h

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/*
 * isdnhdlc.h  --  General purpose ISDN HDLC decoder.
 *
 * Implementation of a HDLC decoder/encoder in software.
 * Necessary because some ISDN devices don't have HDLC
 * controllers.
 *
 * Copyright (C)
 *      2009    Karsten Keil            <keil@b1-systems.de>
 *      2002    Wolfgang Mües           <wolfgang@iksw-muees.de>
 *      2001    Frode Isaksen           <fisaksen@bewan.com>
 *      2001    Kai Germaschewski       <kai.germaschewski@gmx.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
 
#pragma once
 
#include <stdint.h>
 
struct osmo_isdnhdlc_vars {
        int bit_shift;
        int hdlc_bits1;
        int data_bits;
        int ffbit_shift;        /* encoding only */
        int state;
        int dstpos;
 
        uint16_t crc;
 
        uint8_t cbin;
        uint8_t shift_reg;
        uint8_t ffvalue;
 
        /* set if transferring data */
        uint32_t data_received:1;
        /* set if D channel (send idle instead of flags) */
        uint32_t dchannel:1;
        /* set if 56K adaptation */
        uint32_t do_adapt56:1;
        /* set if in closing phase (need to send CRC + flag) */
        uint32_t do_closing:1;
        /* set if data is bitreverse */
        uint32_t do_bitreverse:1;
};
 
/* Feature Flags */
#define OSMO_HDLC_F_56KBIT      0x01
#define OSMO_HDLC_F_DCHANNEL    0x02
#define OSMO_HDLC_F_BITREVERSE  0x04
 
/*
  The return value from isdnhdlc_decode is
  the frame length, 0 if no complete frame was decoded,
  or a negative error number
*/
#define OSMO_HDLC_FRAMING_ERROR     1
#define OSMO_HDLC_CRC_ERROR         2
#define OSMO_HDLC_LENGTH_ERROR      3
 
extern void     osmo_isdnhdlc_rcv_init(struct osmo_isdnhdlc_vars *hdlc, uint32_t features);
 
extern int      osmo_isdnhdlc_decode(struct osmo_isdnhdlc_vars *hdlc, const uint8_t *src,
                                     int slen, int *count, uint8_t *dst, int dsize);
 
extern void     osmo_isdnhdlc_out_init(struct osmo_isdnhdlc_vars *hdlc, uint32_t features);
 
extern int      osmo_isdnhdlc_encode(struct osmo_isdnhdlc_vars *hdlc, const uint8_t *src,
                                     uint16_t slen, int *count, uint8_t *dst, int dsize);