hdlc.h

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00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * hdlc.h
00005  *
00006  * Written by Steve Underwood <steveu@coppice.org>
00007  *
00008  * Copyright (C) 2003 Steve Underwood
00009  *
00010  * All rights reserved.
00011  *
00012  * This program is free software; you can redistribute it and/or modify
00013  * it under the terms of the GNU Lesser General Public License version 2.1,
00014  * as published by the Free Software Foundation.
00015  *
00016  * This program is distributed in the hope that it will be useful,
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  * GNU Lesser General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU Lesser General Public
00022  * License along with this program; if not, write to the Free Software
00023  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00024  *
00025  * $Id: hdlc.h,v 1.40 2008/11/30 05:43:37 steveu Exp $
00026  */
00027 
00028 /*! \file */
00029 
00030 /*! \page hdlc_page HDLC
00031 
00032 \section hdlc_page_sec_1 What does it do?
00033 The HDLC module provides bit stuffing, destuffing, framing and deframing,
00034 according to the HDLC protocol. It also provides 16 and 32 bit CRC generation
00035 and checking services for HDLC frames.
00036 
00037 HDLC may not be a DSP function, but is needed to accompany several DSP components.
00038 
00039 \section hdlc_page_sec_2 How does it work?
00040 */
00041 
00042 #if !defined(_SPANDSP_HDLC_H_)
00043 #define _SPANDSP_HDLC_H_
00044 
00045 /*! 
00046     HDLC_MAXFRAME_LEN is the maximum length of a stuffed HDLC frame, excluding the CRC.
00047 */
00048 #define HDLC_MAXFRAME_LEN       400     
00049 
00050 typedef void (*hdlc_frame_handler_t)(void *user_data, const uint8_t *pkt, int len, int ok);
00051 typedef void (*hdlc_underflow_handler_t)(void *user_data);
00052 
00053 /*!
00054     HDLC receive descriptor. This contains all the state information for an HDLC receiver.
00055  */
00056 typedef struct hdlc_rx_state_s hdlc_rx_state_t;
00057 
00058 /*!
00059     HDLC received data statistics.
00060  */
00061 typedef struct
00062 {
00063     /*! \brief The number of bytes of good frames received (CRC not included). */
00064     unsigned long int bytes;
00065     /*! \brief The number of good frames received. */
00066     unsigned long int good_frames;
00067     /*! \brief The number of frames with CRC errors received. */
00068     unsigned long int crc_errors;
00069     /*! \brief The number of too short and too long frames received. */
00070     unsigned long int length_errors;
00071     /*! \brief The number of HDLC aborts received. */
00072     unsigned long int aborts;
00073 } hdlc_rx_stats_t;
00074 
00075 /*!
00076     HDLC transmit descriptor. This contains all the state information for an
00077     HDLC transmitter.
00078  */
00079 typedef struct hdlc_tx_state_s hdlc_tx_state_t;
00080 
00081 #if defined(__cplusplus)
00082 extern "C"
00083 {
00084 #endif
00085 
00086 /*! \brief Initialise an HDLC receiver context.
00087     \param s A pointer to an HDLC receiver context.
00088     \param crc32 TRUE to use ITU CRC32. FALSE to use ITU CRC16.
00089     \param report_bad_frames TRUE to request the reporting of bad frames.
00090     \param framing_ok_threshold The number of back-to-back flags needed to
00091            start the framing OK condition. This may be used where a series of
00092            flag octets is used as a preamble, such as in the T.30 protocol.
00093     \param handler The function to be called when a good HDLC frame is received.
00094     \param user_data An opaque parameter for the callback routine.
00095     \return A pointer to the HDLC receiver context.
00096 */
00097 hdlc_rx_state_t *hdlc_rx_init(hdlc_rx_state_t *s,
00098                               int crc32,
00099                               int report_bad_frames,
00100                               int framing_ok_threshold,
00101                               hdlc_frame_handler_t handler,
00102                               void *user_data);
00103 
00104 /*! \brief Set the maximum frame length for an HDLC receiver context.
00105     \param s A pointer to an HDLC receiver context.
00106     \param max_len The maximum permitted length of a frame.
00107 */
00108 void hdlc_rx_set_max_frame_len(hdlc_rx_state_t *s, size_t max_len);
00109 
00110 /*! \brief Set the octet counting report interval.
00111     \param s A pointer to an HDLC receiver context.
00112     \param interval The interval, in octets.
00113 */
00114 void hdlc_rx_set_octet_counting_report_interval(hdlc_rx_state_t *s, int interval);
00115 
00116 /*! \brief Get the current receive statistics.
00117     \param s A pointer to an HDLC receiver context.
00118     \param t A pointer to the buffer for the statistics.
00119     \return 0 for OK, else -1.
00120 */
00121 int hdlc_rx_get_stats(hdlc_rx_state_t *s,
00122                       hdlc_rx_stats_t *t);
00123 
00124 /*! \brief Put a single bit of data to an HDLC receiver.
00125     \param s A pointer to an HDLC receiver context.
00126     \param new_bit The bit.
00127 */
00128 void hdlc_rx_put_bit(hdlc_rx_state_t *s, int new_bit);
00129 
00130 /*! \brief Put a byte of data to an HDLC receiver.
00131     \param s A pointer to an HDLC receiver context.
00132     \param new_byte The byte of data.
00133 */
00134 void hdlc_rx_put_byte(hdlc_rx_state_t *s, int new_byte);
00135 
00136 /*! \brief Put a series of bytes of data to an HDLC receiver.
00137     \param s A pointer to an HDLC receiver context.
00138     \param buf The buffer of data.
00139     \param len The length of the data in the buffer.
00140 */
00141 void hdlc_rx_put(hdlc_rx_state_t *s, const uint8_t buf[], int len);
00142 
00143 /*! \brief Initialise an HDLC transmitter context.
00144     \param s A pointer to an HDLC transmitter context.
00145     \param crc32 TRUE to use ITU CRC32. FALSE to use ITU CRC16.
00146     \param inter_frame_flags The minimum flag octets to insert between frames (usually one).
00147     \param progressive TRUE if frame creation works in progressive mode.
00148     \param handler The callback function called when the HDLC transmitter underflows.
00149     \param user_data An opaque parameter for the callback routine.
00150     \return A pointer to the HDLC transmitter context.
00151 */
00152 hdlc_tx_state_t *hdlc_tx_init(hdlc_tx_state_t *s,
00153                               int crc32,
00154                               int inter_frame_flags,
00155                               int progressive,
00156                               hdlc_underflow_handler_t handler,
00157                               void *user_data);
00158 
00159 /*! \brief Set the maximum frame length for an HDLC transmitter context.
00160     \param s A pointer to an HDLC transmitter context.
00161     \param max_len The maximum length.
00162 */
00163 void hdlc_tx_set_max_frame_len(hdlc_tx_state_t *s, size_t max_len);
00164 
00165 /*! \brief Transmit a frame.
00166     \param s A pointer to an HDLC transmitter context.
00167     \param frame A pointer to the frame to be transmitted.
00168     \param len The length of the frame to be transmitted.
00169     \return 0 if the frame was accepted for transmission, else -1.
00170 */
00171 int hdlc_tx_frame(hdlc_tx_state_t *s, const uint8_t *frame, size_t len);
00172 
00173 /*! \brief Corrupt the frame currently being transmitted, by giving it the wrong CRC.
00174     \param s A pointer to an HDLC transmitter context.
00175     \return 0 if the frame was corrupted, else -1.
00176 */
00177 int hdlc_tx_corrupt_frame(hdlc_tx_state_t *s);
00178 
00179 /*! \brief Transmit a specified quantity of flag octets, typically as a preamble.
00180     \param s A pointer to an HDLC transmitter context.
00181     \param len The length of the required period of flags, in flag octets. If len is zero this
00182            requests that HDLC transmission be terminated when the buffers have fully
00183            drained.
00184     \return 0 if the flags were accepted for transmission, else -1.
00185 */
00186 int hdlc_tx_flags(hdlc_tx_state_t *s, int len);
00187 
00188 /*! \brief Send an abort.
00189     \param s A pointer to an HDLC transmitter context.
00190     \return 0 if the frame was aborted, else -1.
00191 */
00192 int hdlc_tx_abort(hdlc_tx_state_t *s);
00193 
00194 /*! \brief Get the next bit for transmission.
00195     \param s A pointer to an HDLC transmitter context.
00196     \return The next bit for transmission.
00197 */
00198 int hdlc_tx_get_bit(hdlc_tx_state_t *s);
00199 
00200 /*! \brief Get the next byte for transmission.
00201     \param s A pointer to an HDLC transmitter context.
00202     \return The next byte for transmission.
00203 */
00204 int hdlc_tx_get_byte(hdlc_tx_state_t *s);
00205 
00206 /*! \brief Get the next sequence of bytes for transmission.
00207     \param s A pointer to an HDLC transmitter context.
00208     \param buf The buffer for the data.
00209     \param max_len The number of bytes to get.
00210     \return The number of bytes actually got.
00211 */
00212 int hdlc_tx_get(hdlc_tx_state_t *s, uint8_t buf[], size_t max_len);
00213 
00214 #if defined(__cplusplus)
00215 }
00216 #endif
00217 
00218 #endif
00219 /*- End of file ------------------------------------------------------------*/

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