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Diffstat (limited to 'include/osmocom/sgsn/v42bis.h')
| -rw-r--r-- | include/osmocom/sgsn/v42bis.h | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/include/osmocom/sgsn/v42bis.h b/include/osmocom/sgsn/v42bis.h new file mode 100644 index 000000000..607a58e51 --- /dev/null +++ b/include/osmocom/sgsn/v42bis.h @@ -0,0 +1,147 @@ +/* + * SpanDSP - a series of DSP components for telephony + * + * v42bis.h + * + * Written by Steve Underwood <steveu@coppice.org> + * + * Copyright (C) 2005, 2011 Steve Underwood + * + * All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License version 2.1, + * as published by the Free Software Foundation. + * + * 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 Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +/*! \page v42bis_page V.42bis modem data compression +\section v42bis_page_sec_1 What does it do? +The v.42bis specification defines a data compression scheme, to work in +conjunction with the error correction scheme defined in V.42. + +\section v42bis_page_sec_2 How does it work? +*/ + +#include <stdint.h> + +#if !defined(_SPANDSP_V42BIS_H_) +#define _SPANDSP_V42BIS_H_ + +#define SPAN_DECLARE(x) x + +#define V42BIS_MIN_STRING_SIZE 6 +#define V42BIS_MAX_STRING_SIZE 250 +#define V42BIS_MIN_DICTIONARY_SIZE 512 +#define V42BIS_MAX_BITS 12 +#define V42BIS_MAX_CODEWORDS 4096 /* 2^V42BIS_MAX_BITS */ +#define V42BIS_MAX_OUTPUT_LENGTH 1024 + +enum +{ + V42BIS_P0_NEITHER_DIRECTION = 0, + V42BIS_P0_INITIATOR_RESPONDER, + V42BIS_P0_RESPONDER_INITIATOR, + V42BIS_P0_BOTH_DIRECTIONS +}; + +enum +{ + V42BIS_COMPRESSION_MODE_DYNAMIC = 0, + V42BIS_COMPRESSION_MODE_ALWAYS, + V42BIS_COMPRESSION_MODE_NEVER +}; + +typedef void (*put_msg_func_t)(void *user_data, const uint8_t *msg, int len); + +/*! + V.42bis compression/decompression descriptor. This defines the working state for a + single instance of V.42bis compress/decompression. +*/ +typedef struct v42bis_state_s v42bis_state_t; + +#if defined(__cplusplus) +extern "C" +{ +#endif + +/*! Compress a block of octets. + \param s The V.42bis context. + \param buf The data to be compressed. + \param len The length of the data buffer. + \return 0 */ +SPAN_DECLARE(int) v42bis_compress(v42bis_state_t *s, const uint8_t buf[], int len); + +/*! Flush out any data remaining in a compression buffer. + \param s The V.42bis context. + \return 0 */ +SPAN_DECLARE(int) v42bis_compress_flush(v42bis_state_t *s); + +/*! Decompress a block of octets. + \param s The V.42bis context. + \param buf The data to be decompressed. + \param len The length of the data buffer. + \return 0 */ +SPAN_DECLARE(int) v42bis_decompress(v42bis_state_t *s, const uint8_t buf[], int len); + +/*! Flush out any data remaining in the decompression buffer. + \param s The V.42bis context. + \return 0 */ +SPAN_DECLARE(int) v42bis_decompress_flush(v42bis_state_t *s); + +/*! Set the compression mode. + \param s The V.42bis context. + \param mode One of the V.42bis compression modes - + V42BIS_COMPRESSION_MODE_DYNAMIC, + V42BIS_COMPRESSION_MODE_ALWAYS, + V42BIS_COMPRESSION_MODE_NEVER */ +SPAN_DECLARE(void) v42bis_compression_control(v42bis_state_t *s, int mode); + +/*! Initialise a V.42bis context. + \param s The V.42bis context. + \param negotiated_p0 The negotiated P0 parameter, from the V.42bis spec. + \param negotiated_p1 The negotiated P1 parameter, from the V.42bis spec. + \param negotiated_p2 The negotiated P2 parameter, from the V.42bis spec. + \param encode_handler Encode callback handler. + \param encode_user_data An opaque pointer passed to the encode callback handler. + \param max_encode_len The maximum length that should be passed to the encode handler. + \param decode_handler Decode callback handler. + \param decode_user_data An opaque pointer passed to the decode callback handler. + \param max_decode_len The maximum length that should be passed to the decode handler. + \return The V.42bis context. */ +SPAN_DECLARE(v42bis_state_t *) v42bis_init(const void *ctx, + v42bis_state_t *s, + int negotiated_p0, + int negotiated_p1, + int negotiated_p2, + put_msg_func_t encode_handler, + void *encode_user_data, + int max_encode_len, + put_msg_func_t decode_handler, + void *decode_user_data, + int max_decode_len); + +/*! Release a V.42bis context. + \param s The V.42bis context. + \return 0 if OK */ +SPAN_DECLARE(int) v42bis_release(v42bis_state_t *s); + +/*! Free a V.42bis context. + \param s The V.42bis context. + \return 0 if OK */ +SPAN_DECLARE(int) v42bis_free(v42bis_state_t *s); + +#if defined(__cplusplus) +} +#endif + +#endif +/*- End of file ------------------------------------------------------------*/ |