sdvl.h

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/*
 * Copyright 2011,2012,2013 Didier Barvaux
 * Copyright 2007,2009,2010,2013 Viveris Technologies
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

/**
 * @file sdvl.h
 * @brief Self-Describing Variable-Length (SDVL) encoding
 * @author Didier Barvaux <didier.barvaux@toulouse.viveris.com>
 * @author Didier Barvaux <didier@barvaux.org>
 */

#ifndef ROHC_COMMON_SDVL_H
#define ROHC_COMMON_SDVL_H

#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>


/*
 * Constants related to fields length for SDVL-encoding
 */

/** The maximum numbers of bits that can be SDVL-encoded in 1, 2, 3
 *  and 4 bytes */
typedef enum
{
        /** Maximum number of bits in 1 SDVL-encoded byte */
        ROHC_SDVL_MAX_BITS_IN_1_BYTE = 7U,
        /** Maximum number of bits in 2 SDVL-encoded bytes */
        ROHC_SDVL_MAX_BITS_IN_2_BYTES = 14U,
        /** Maximum number of bits in 3 SDVL-encoded bytes */
        ROHC_SDVL_MAX_BITS_IN_3_BYTES = 21U,
        /** Maximum number of bits in 4 sdvl_sn_lsb() bytes as defined in RFC5225 */
        ROHC_SDVL_MAX_BITS_IN_4_BYTES_RFC5225 = 28U,
        /** Maximum number of bits in 4 SDVL-encoded bytes */
        ROHC_SDVL_MAX_BITS_IN_4_BYTES = 29U,
        /** Maximum number of bits in 5 sdvl_sn_lsb() bytes as defined in RFC5225 */
        ROHC_SDVL_MAX_BITS_IN_5_BYTES_RFC5225 = 32U,
} rohc_sdvl_max_bits_t;


/*
 * Function prototypes.
 */

bool sdvl_can_value_be_encoded(const uint32_t value)
        __attribute__((warn_unused_result, const));
bool sdvl_can_length_be_encoded(const size_t bits_nr)
        __attribute__((warn_unused_result, const));

size_t sdvl_get_min_len(const size_t nr_min_required, const size_t nr_encoded)
        __attribute__((warn_unused_result, const));

size_t sdvl_get_encoded_len(const uint32_t value)
        __attribute__((warn_unused_result, const));

bool sdvl_encode(uint8_t *const packet,
                 const size_t packet_max_len,
                 size_t *const packet_len,
                 const uint32_t value,
                 const size_t bits_nr)
        __attribute__((warn_unused_result, nonnull(1, 3)));

bool sdvl_encode_full(uint8_t *const packet,
                      const size_t packet_max_len,
                      size_t *const packet_len,
                      const uint32_t value)
        __attribute__((warn_unused_result, nonnull(1, 3)));

size_t sdvl_decode(const uint8_t *const data,
                   const size_t length,
                   uint32_t *const value,
                   size_t *const bits_nr)
        __attribute__((warn_unused_result, nonnull(1, 3, 4)));

#endif