--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.3/spandsp-0.0.3/src/spandsp/v42bis.h	Fri Jun 25 16:00:21 2010 +0200
@@ -0,0 +1,236 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * v42bis.h
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2005 Steve Underwood
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id: v42bis.h,v 1.15 2006/11/30 15:41:47 steveu Exp $
+ */
+
+/*! \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?
+*/
+
+#if !defined(_V42BIS_H_)
+#define _V42BIS_H_
+
+#define V42BIS_MAX_BITS         12
+#define V42BIS_MAX_CODEWORDS    4096    /* 2^V42BIS_MAX_BITS */
+#define V42BIS_TABLE_SIZE       5021    /* This should be a prime >(2^V42BIS_MAX_BITS) */
+#define V42BIS_MAX_STRING_SIZE  250
+
+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 (*v42bis_frame_handler_t)(void *user_data, const uint8_t *pkt, int len);
+typedef void (*v42bis_data_handler_t)(void *user_data, const uint8_t *buf, int len);
+
+typedef struct
+{
+    /*! \brief The prior code for each defined code. */
+    uint16_t parent_code;
+    /*! \brief The number of leaf nodes this node has */
+    int16_t leaves;
+    /*! \brief This leaf octet for each defined code. */
+    uint8_t node_octet;
+    /*! \brief Bit map of the children which exist */
+    uint32_t children[8];
+} v42bis_dict_node_t;
+
+typedef struct
+{
+    /*! \brief Compression mode. */
+    int compression_mode;
+    /*! \brief Callback function to handle received frames. */
+    v42bis_frame_handler_t handler;
+    /*! \brief An opaque pointer passed in calls to frame_handler. */
+    void *user_data;
+    /*! \brief The maximum frame length allowed */
+    int max_len;
+
+    uint32_t string_code;
+    uint32_t latest_code;
+    int string_length;
+    uint32_t output_bit_buffer;
+    int output_bit_count;
+    int output_octet_count;
+    uint8_t output_buf[1024];
+    v42bis_dict_node_t dict[V42BIS_MAX_CODEWORDS];
+    /*! \brief TRUE if we are in transparent (i.e. uncompressable) mode */
+    int transparent;
+    int change_transparency;
+    int compressibility_filter;
+    int compressibility_persistence;
+    
+    /*! \brief Next empty dictionary entry */
+    uint32_t v42bis_parm_c1;
+    /*! \brief Current codeword size */
+    int v42bis_parm_c2;
+    /*! \brief Threshold for codeword size change */
+    uint32_t v42bis_parm_c3;
+
+    /*! \brief Mark that this is the first octet/code to be processed */
+    int first;
+    uint8_t escape_code;
+} v42bis_compress_state_t;
+
+typedef struct
+{
+    /*! \brief Callback function to handle decompressed data. */
+    v42bis_data_handler_t handler;
+    /*! \brief An opaque pointer passed in calls to data_handler. */
+    void *user_data;
+    /*! \brief The maximum decompressed data block length allowed */
+    int max_len;
+
+    uint32_t old_code;
+    uint32_t last_old_code;
+    uint32_t input_bit_buffer;
+    int input_bit_count;
+    int octet;
+    int last_length;
+    int output_octet_count;
+    uint8_t output_buf[1024];
+    v42bis_dict_node_t dict[V42BIS_MAX_CODEWORDS];
+    /*! \brief TRUE if we are in transparent (i.e. uncompressable) mode */
+    int transparent;
+
+    int last_extra_octet;
+
+    /*! \brief Next empty dictionary entry */
+    int v42bis_parm_c1;
+    /*! \brief Current codeword size */
+    int v42bis_parm_c2;
+    /*! \brief Threshold for codeword size change */
+    int v42bis_parm_c3;
+        
+    /*! \brief Mark that this is the first octet/code to be processed */
+    int first;
+    uint8_t escape_code;
+    int escaped;
+} v42bis_decompress_state_t;
+
+/*!
+    V.42bis compression/decompression descriptor. This defines the working state for a
+    single instance of V.42bis compress/decompression.
+*/
+typedef struct
+{
+    /*! \brief V.42bis data compression directions. */
+    int v42bis_parm_p0;
+
+    v42bis_compress_state_t compress;
+    v42bis_decompress_state_t decompress;
+    
+    /*! \brief Maximum codeword size (bits) */
+    int v42bis_parm_n1;
+    /*! \brief Total number of codewords */
+    uint32_t v42bis_parm_n2;
+    /*! \brief Maximum string length */
+    int v42bis_parm_n7;
+} v42bis_state_t;
+
+#ifdef __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 */
+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 */
+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 */
+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 */
+int v42bis_decompress_flush(v42bis_state_t *s);
+
+/*! 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 frame_handler .
+    \param frame_user_data .
+    \param max_frame_len The maximum length that should be passed to the frame handler.
+    \param data_handler .
+    \param data_user_data .
+    \param max_data_len The maximum length that should be passed to the data handler.
+    \return The V.42bis context. */
+v42bis_state_t *v42bis_init(v42bis_state_t *s,
+                            int negotiated_p0,
+                            int negotiated_p1,
+                            int negotiated_p2,
+                            v42bis_frame_handler_t frame_handler,
+                            void *frame_user_data,
+                            int max_frame_len,
+                            v42bis_data_handler_t data_handler,
+                            void *data_user_data,
+                            int max_data_len);
+
+/*! 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 */
+void v42bis_compression_control(v42bis_state_t *s, int mode);
+
+/*! Release a V.42bis context.
+    \param s The V.42bis context.
+    \return 0 if OK */
+int v42bis_release(v42bis_state_t *s);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/