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+/*
+ * 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 ------------------------------------------------------------*/