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 General Public License version 2, as 00014 * 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 General Public License for more details. 00020 * 00021 * You should have received a copy of the GNU General Public License 00022 * 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 1.36 2007/08/25 05:10:42 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 00057 { 00058 /*! 2 for CRC-16, 4 for CRC-32 */ 00059 int crc_bytes; 00060 /*! \brief Maximum permitted frame length. */ 00061 size_t max_frame_len; 00062 /*! \brief The callback routine called to process each good received frame. */ 00063 hdlc_frame_handler_t frame_handler; 00064 /*! \brief An opaque parameter passed to the callback routine. */ 00065 void *user_data; 00066 /*! \brief TRUE if bad frames are to be reported. */ 00067 int report_bad_frames; 00068 /*! \brief The number of consecutive flags which must be seen before framing is 00069 declared OK. */ 00070 int framing_ok_threshold; 00071 /*! \brief TRUE if framing OK has been announced. */ 00072 int framing_ok_announced; 00073 /*! \brief Number of consecutive flags seen so far. */ 00074 int flags_seen; 00075 00076 /*! \brief The raw (stuffed) bit stream buffer. */ 00077 unsigned int raw_bit_stream; 00078 /*! \brief The destuffed bit stream buffer. */ 00079 unsigned int byte_in_progress; 00080 /*! \brief The current number of bits in byte_in_progress. */ 00081 int num_bits; 00082 int octet_counting_mode; 00083 /*! \brief Octet count, to achieve the functionality needed for things 00084 like MTP. */ 00085 int octet_count; 00086 int octet_count_report_interval; 00087 00088 /*! \brief Buffer for a frame in progress. */ 00089 uint8_t buffer[HDLC_MAXFRAME_LEN + 4]; 00090 /*! \brief Length of a frame in progress. */ 00091 size_t len; 00092 00093 /*! \brief The number of bytes of good frames received (CRC not included). */ 00094 unsigned long int rx_bytes; 00095 /*! \brief The number of good frames received. */ 00096 unsigned long int rx_frames; 00097 /*! \brief The number of frames with CRC errors received. */ 00098 unsigned long int rx_crc_errors; 00099 /*! \brief The number of too short and too long frames received. */ 00100 unsigned long int rx_length_errors; 00101 /*! \brief The number of HDLC aborts received. */ 00102 unsigned long int rx_aborts; 00103 } hdlc_rx_state_t; 00104 00105 /*! 00106 HDLC received data statistics. 00107 */ 00108 typedef struct 00109 { 00110 /*! \brief The number of bytes of good frames received (CRC not included). */ 00111 unsigned long int bytes; 00112 /*! \brief The number of good frames received. */ 00113 unsigned long int good_frames; 00114 /*! \brief The number of frames with CRC errors received. */ 00115 unsigned long int crc_errors; 00116 /*! \brief The number of too short and too long frames received. */ 00117 unsigned long int length_errors; 00118 /*! \brief The number of HDLC aborts received. */ 00119 unsigned long int aborts; 00120 } hdlc_rx_stats_t; 00121 00122 /*! 00123 HDLC transmit descriptor. This contains all the state information for an 00124 HDLC transmitter. 00125 */ 00126 typedef struct 00127 { 00128 /*! 2 for CRC-16, 4 for CRC-32 */ 00129 int crc_bytes; 00130 /*! \brief The callback routine called to indicate transmit underflow. */ 00131 hdlc_underflow_handler_t underflow_handler; 00132 /*! \brief An opaque parameter passed to the callback routine. */ 00133 void *user_data; 00134 /*! \brief The minimum flag octets to insert between frames. */ 00135 int inter_frame_flags; 00136 /*! \brief TRUE if frame creation works in progressive mode. */ 00137 int progressive; 00138 /*! \brief Maximum permitted frame length. */ 00139 size_t max_frame_len; 00140 00141 /*! \brief The stuffed bit stream being created. */ 00142 uint32_t octets_in_progress; 00143 /*! \brief The number of bits currently in octets_in_progress. */ 00144 int num_bits; 00145 /*! \brief The currently rotated state of the flag octet. */ 00146 int idle_octet; 00147 /*! \brief The number of flag octets to send for a timed burst of flags. */ 00148 int flag_octets; 00149 /*! \brief The number of abort octets to send for a timed burst of aborts. */ 00150 int abort_octets; 00151 /*! \brief TRUE if the next underflow of timed flag octets should be reported */ 00152 int report_flag_underflow; 00153 00154 /*! \brief The current message being transmitted, with its CRC attached. */ 00155 uint8_t buffer[HDLC_MAXFRAME_LEN + 4]; 00156 /*! \brief The length of the message in the buffer. */ 00157 size_t len; 00158 /*! \brief The current send position within the buffer. */ 00159 int pos; 00160 /*! \brief The running CRC, as data fills the frame buffer. */ 00161 uint32_t crc; 00162 00163 /*! \brief The current byte being broken into bits for transmission. */ 00164 int byte; 00165 /*! \brief The number of bits remaining in byte. */ 00166 int bits; 00167 00168 /*! \brief TRUE if transmission should end on buffer underflow .*/ 00169 int tx_end; 00170 } hdlc_tx_state_t; 00171 00172 #if defined(__cplusplus) 00173 extern "C" 00174 { 00175 #endif 00176 00177 /*! \brief Initialise an HDLC receiver context. 00178 \param s A pointer to an HDLC receiver context. 00179 \param crc32 TRUE to use ITU CRC32. FALSE to use ITU CRC16. 00180 \param report_bad_frames TRUE to request the reporting of bad frames. 00181 \param framing_ok_threshold The number of back-to-back flags needed to 00182 start the framing OK condition. This may be used where a series of 00183 flag octets is used as a preamble, such as in the T.30 protocol. 00184 \param handler The function to be called when a good HDLC frame is received. 00185 \param user_data An opaque parameter for the callback routine. 00186 \return A pointer to the HDLC receiver context. 00187 */ 00188 hdlc_rx_state_t *hdlc_rx_init(hdlc_rx_state_t *s, 00189 int crc32, 00190 int report_bad_frames, 00191 int framing_ok_threshold, 00192 hdlc_frame_handler_t handler, 00193 void *user_data); 00194 00195 /*! \brief Set the maximum frame length for an HDLC receiver context. 00196 \param s A pointer to an HDLC receiver context. 00197 \param max_len The maximum permitted length of a frame. 00198 */ 00199 void hdlc_rx_set_max_frame_len(hdlc_rx_state_t *s, size_t max_len); 00200 00201 /*! \brief Set the octet counting report interval. 00202 \param s A pointer to an HDLC receiver context. 00203 \param interval The interval, in octets. 00204 */ 00205 void hdlc_rx_set_octet_counting_report_interval(hdlc_rx_state_t *s, int interval); 00206 00207 /*! \brief Get the current receive statistics. 00208 \param s A pointer to an HDLC receiver context. 00209 \param t A pointer to the buffer for the statistics. 00210 \return 0 for OK, else -1. 00211 */ 00212 int hdlc_rx_get_stats(hdlc_rx_state_t *s, 00213 hdlc_rx_stats_t *t); 00214 00215 /*! \brief Put a single bit of data to an HDLC receiver. 00216 \param s A pointer to an HDLC receiver context. 00217 \param new_bit The bit. 00218 */ 00219 void hdlc_rx_put_bit(hdlc_rx_state_t *s, int new_bit); 00220 00221 /*! \brief Put a byte of data to an HDLC receiver. 00222 \param s A pointer to an HDLC receiver context. 00223 \param new_byte The byte of data. 00224 */ 00225 void hdlc_rx_put_byte(hdlc_rx_state_t *s, int new_byte); 00226 00227 /*! \brief Put a series of bytes of data to an HDLC receiver. 00228 \param s A pointer to an HDLC receiver context. 00229 \param buf The buffer of data. 00230 \param len The length of the data in the buffer. 00231 */ 00232 void hdlc_rx_put(hdlc_rx_state_t *s, const uint8_t buf[], int len); 00233 00234 /*! \brief Initialise an HDLC transmitter context. 00235 \param s A pointer to an HDLC transmitter context. 00236 \param crc32 TRUE to use ITU CRC32. FALSE to use ITU CRC16. 00237 \param inter_frame_flags The minimum flag octets to insert between frames (usually one). 00238 \param progressive TRUE if frame creation works in progressive mode. 00239 \param handler The callback function called when the HDLC transmitter underflows. 00240 \param user_data An opaque parameter for the callback routine. 00241 \return A pointer to the HDLC transmitter context. 00242 */ 00243 hdlc_tx_state_t *hdlc_tx_init(hdlc_tx_state_t *s, 00244 int crc32, 00245 int inter_frame_flags, 00246 int progressive, 00247 hdlc_underflow_handler_t handler, 00248 void *user_data); 00249 00250 /*! \brief Set the maximum frame length for an HDLC transmitter context. 00251 \param s A pointer to an HDLC transmitter context. 00252 \param max_len The maximum length. 00253 */ 00254 void hdlc_tx_set_max_frame_len(hdlc_tx_state_t *s, size_t max_len); 00255 00256 /*! \brief Transmit a frame. 00257 \param s A pointer to an HDLC transmitter context. 00258 \param frame A pointer to the frame to be transmitted. 00259 \param len The length of the frame to be transmitted. 00260 \return 0 if the frame was accepted for transmission, else -1. 00261 */ 00262 int hdlc_tx_frame(hdlc_tx_state_t *s, const uint8_t *frame, size_t len); 00263 00264 /*! \brief Corrupt the frame currently being transmitted, by giving it the wrong CRC. 00265 \param s A pointer to an HDLC transmitter context. 00266 \return 0 if the frame was corrupted, else -1. 00267 */ 00268 int hdlc_tx_corrupt_frame(hdlc_tx_state_t *s); 00269 00270 /*! \brief Transmit a specified quantity of flag octets, typically as a preamble. 00271 \param s A pointer to an HDLC transmitter context. 00272 \param len The length of the required period of flags, in flag octets. If len is zero this 00273 requests that HDLC transmission be terminated when the buffers have fully 00274 drained. 00275 \return 0 if the flags were accepted for transmission, else -1. 00276 */ 00277 int hdlc_tx_flags(hdlc_tx_state_t *s, int len); 00278 00279 /*! \brief Send an abort. 00280 \param s A pointer to an HDLC transmitter context. 00281 \return 0 if the frame was aborted, else -1. 00282 */ 00283 int hdlc_tx_abort(hdlc_tx_state_t *s); 00284 00285 /*! \brief Get the next bit for transmission. 00286 \param s A pointer to an HDLC transmitter context. 00287 \return The next bit for transmission. 00288 */ 00289 int hdlc_tx_get_bit(hdlc_tx_state_t *s); 00290 00291 /*! \brief Get the next byte for transmission. 00292 \param s A pointer to an HDLC transmitter context. 00293 \return The next byte for transmission. 00294 */ 00295 int hdlc_tx_get_byte(hdlc_tx_state_t *s); 00296 00297 /*! \brief Get the next sequence of bytes for transmission. 00298 \param s A pointer to an HDLC transmitter context. 00299 \param buf The buffer for the data. 00300 \param len The number of bytes to get. 00301 \return The number of bytes actually got. 00302 */ 00303 int hdlc_tx_get(hdlc_tx_state_t *s, uint8_t buf[], size_t max_len); 00304 00305 #if defined(__cplusplus) 00306 } 00307 #endif 00308 00309 #endif 00310 /*- End of file ------------------------------------------------------------*/