rohc_decomp_internals.h

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/**
 * @file    rohc_decomp_internals.h
 * @brief   Internal structures for ROHC decompression
 * @author  Didier Barvaux <didier.barvaux@toulouse.viveris.com>
 * @author  Didier Barvaux <didier@barvaux.org>
 * @author  The hackers from ROHC for Linux
 * @author  David Moreau from TAS
 */

#ifndef ROHC_DECOMP_INTERNALS_H
#define ROHC_DECOMP_INTERNALS_H

#include "rohc.h" /* for struct medium */
#include "rohc_comp.h"



/*
 * Constants and macros
 */


/** The number of ROHC profiles ready to be used */
#define D_NUM_PROFILES 6

/** Print a debug trace for the given decompression context */
#define rohc_decomp_debug(context, format, ...) \
        rohc_debug((context)->decompressor, ROHC_TRACE_DECOMP, \
                   (context)->profile->id, \
                   format, ##__VA_ARGS__)


/*
 * Definitions of ROHC compression structures
 */


/**
 * @brief Some compressor statistics
 */
struct d_statistics
{
        /* The number of received packets */
        unsigned int received;
        /* The number of bad decompressions due to wrong CRC */
        unsigned int failed_crc;
        /* The number of bad decompressions due to being in the No Context state */
        unsigned int failed_no_context;
        /* The number of bad decompressions */
        unsigned int failed_decomp;
        /* The number of feedback packets sent to the associated compressor */
        unsigned int feedbacks;
};


/**
 * @brief The ROHC decompressor
 */
struct rohc_decomp
{
        /** The compressor associated with the decompressor */
        struct rohc_comp *compressor;

        /** The medium associated with the decompressor */
        struct medium medium;

        /** The array of decompression contexts that use the decompressor */
        struct d_context **contexts;
        /** The last decompression context used by the decompressor */
        struct d_context *last_context;

        /**
         * @brief The feedback interval limits
         *
         * maxval can be updated by the user thanks to the user_interactions
         * function.
         *
         * @see user_interactions
         */
        unsigned int maxval;
        /** Variable related to the feedback interval */
        unsigned int errval;
        /** Variable related to the feedback interval */
        unsigned int okval;
        /** Variable related to the feedback interval */
        int curval;


        /* segment-related variables */

/** The maximal value for MRRU */
#define ROHC_MAX_MRRU 65535
        /** The Reconstructed Reception Unit */
        unsigned char rru[ROHC_MAX_MRRU];
        /** The length (in bytes) of the Reconstructed Reception Unit */
        size_t rru_len;
        /** The Maximum Reconstructed Reception Unit (MRRU) */
        size_t mrru;


        /* CRC-related variables: */

        /** The table to enable fast CRC-2 computation */
        unsigned char crc_table_2[256];
        /** The table to enable fast CRC-3 computation */
        unsigned char crc_table_3[256];
        /** The table to enable fast CRC-6 computation */
        unsigned char crc_table_6[256];
        /** The table to enable fast CRC-7 computation */
        unsigned char crc_table_7[256];
        /** The table to enable fast CRC-8 computation */
        unsigned char crc_table_8[256];


        /** Some statistics about the decompression processes */
        struct d_statistics stats;

        /** The callback function used to get log messages */
        rohc_trace_callback_t trace_callback;
};


/**
 * @brief The ROHC decompression context
 */
struct d_context
{
        /** The Context IDentifier (CID) */
        unsigned int cid;

        /** The associated decompressor */
        struct rohc_decomp *decompressor;

        /** The associated profile */
        struct d_profile *profile;
        /** Profile-specific data, defined by the profiles */
        void *specific;

        /** The operation mode in which the context operates */
        rohc_mode mode;
        /** The operation state in which the context operates */
        rohc_d_state state;

        /** Usage timestamp */
        unsigned int latest_used;
        /** Usage timestamp */
        unsigned int first_used;

        /** Variable related to feedback interval */
        int curval;

        /* below are some statistics */

        /** The average size of the uncompressed packets */
        int total_uncompressed_size;
        /** The average size of the compressed packets */
        int total_compressed_size;
        /** The average size of the uncompressed headers */
        int header_uncompressed_size;
        /** The average size of the compressed headers */
        int header_compressed_size;

        /* The number of received packets */
        int num_recv_packets;
        /* The number of received IR packets */
        int num_recv_ir;
        /* The number of received IR-DYN packets */
        int num_recv_ir_dyn;
        /* The number of sent feedbacks */
        int num_sent_feedbacks;

        /* The number of compression failures */
        int num_decomp_failures;
        /* The number of decompression failures */
        int num_decomp_repairs;

        /* The size of the last 16 uncompressed packets */
        struct c_wlsb *total_16_uncompressed;
        /* The size of the last 16 compressed packets */
        struct c_wlsb *total_16_compressed;
        /* The size of the last 16 uncompressed headers */
        struct c_wlsb *header_16_uncompressed;
        /* The size of the last 16 compressed headers */
        struct c_wlsb *header_16_compressed;

        /** The number of (possible) lost packet(s) before last packet */
        unsigned long nr_lost_packets;
        /** The number of packet(s) before the last packet if late */
        unsigned long nr_misordered_packets;
        /** Is last packet a (possible) duplicated packet? */
        bool is_duplicated;
};


/**
 * @brief The ROHC decompression profile.
 *
 * The object defines a ROHC profile. Each field must be filled in
 * for each new profile.
 */
struct d_profile
{
        /* The profile ID as reserved by IANA */
        int id;

        /* A string that describes the profile */
        char *description;

        /* The handler used to decode a ROHC packet */
        int (*decode)(struct rohc_decomp *decomp,
                      struct d_context *context,
                      const unsigned char *const rohc_packet,
                      const unsigned int rohc_length,
                      const size_t add_cid_len,
                      const size_t large_cid_len,
                      unsigned char *dest);

        /* @brief The handler used to create the profile-specific part of the
         *        decompression context */
        void * (*allocate_decode_data)(const struct d_context *const context);

        /* @brief The handler used to destroy the profile-specific part of the
         *        decompression context */
        void (*free_decode_data)(void *const context);

        /* The handler used to retrieve the Sequence Number (SN) */
        int (*get_sn)(struct d_context *const context);
};



/*
 * Prototypes of library-private functions
 */

void d_change_mode_feedback(struct rohc_decomp *decomp,
                            struct d_context *context);


#endif