rlp.h

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/*
 * GSM RLP (Radio Link Protocol) as used in CSD (3GPP TS 44.022)
 *
 * Copyright (C) 2022-2023 Harald Welte <laforge@osmocom.org>
 *
 * 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 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.
 */
 
 
 
#pragma once
#include <stdint.h>
#include <stdbool.h>
#include <osmocom/core/utils.h>


enum osmo_rlp_ftype {
        OSMO_RLP_FT_U,
        OSMO_RLP_FT_S,
        OSMO_RLP_FT_IS,
};
extern const struct value_string osmo_rlp_ftype_vals[];

enum osmo_rlp_u_ftype {
        OSMO_RLP_U_FT_SABM      = 0x07,
        OSMO_RLP_U_FT_UA        = 0x0c,
        OSMO_RLP_U_FT_DISC      = 0x08,
        OSMO_RLP_U_FT_DM        = 0x03,
        OSMO_RLP_U_FT_NULL      = 0x0f,
        OSMO_RLP_U_FT_UI        = 0x00,
        OSMO_RLP_U_FT_XID       = 0x17,
        OSMO_RLP_U_FT_TEST      = 0x1c,
        OSMO_RLP_U_FT_REMAP     = 0x11,
};
extern const struct value_string osmo_rlp_ftype_u_vals[];

enum osmo_rlp_s_ftype {
        OSMO_RLP_S_FT_RR        = 0,
        OSMO_RLP_S_FT_REJ       = 2,
        OSMO_RLP_S_FT_RNR       = 1,
        OSMO_RLP_S_FT_SREJ      = 3,
};
extern const struct value_string osmo_rlp_ftype_s_vals[];

struct osmo_rlp_frame_decoded {
        uint8_t version;
        enum osmo_rlp_ftype ftype;
        enum osmo_rlp_u_ftype u_ftype;
        enum osmo_rlp_s_ftype s_ftype;
        bool c_r;
        bool p_f;
        uint8_t s_bits;
        uint16_t n_s;
        uint16_t n_r;
        uint32_t fcs;
        uint8_t info[536/8];
        uint16_t info_len;
};
 
int osmo_rlp_decode(struct osmo_rlp_frame_decoded *out, uint8_t version, const uint8_t *data, size_t data_len);
int osmo_rlp_encode(uint8_t *out, size_t out_size, const struct osmo_rlp_frame_decoded *in);
uint32_t osmo_rlp_fcs_compute(const uint8_t *in, size_t in_len);