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/*! \file i460_mux.h
* ITU-T I.460 sub-channel multiplexer + demultiplexer */
/*
* (C) 2020 by Harald Welte <laforge@gnumonks.org>
*
* SPDX-License-Identifier: GPL-2.0+
*
* 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., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#pragma once
#include <stdint.h>
#include <osmocom/core/bits.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/msgb.h>
/* I.460 sub-slot rate */
enum osmo_i460_rate {
OSMO_I460_RATE_NONE, /* disabled */
OSMO_I460_RATE_64k,
OSMO_I460_RATE_32k,
OSMO_I460_RATE_16k,
OSMO_I460_RATE_8k,
};
typedef void (*out_cb_bits_t)(void *user_data, const ubit_t *bits, unsigned int num_bits);
typedef void (*out_cb_bytes_t)(void *user_data, const uint8_t *bytes, unsigned int num_bytes);
struct osmo_i460_subchan_demux {
/*! bit-buffer for output bits */
uint8_t *out_bitbuf;
/*! size of out_bitbuf in bytes */
unsigned int out_bitbuf_size;
/*! offset of next bit to be written in out_bitbuf */
unsigned int out_idx;
/*! callback to be called once we have received out_bitbuf_size bits */
out_cb_bits_t out_cb_bits;
out_cb_bytes_t out_cb_bytes;
void *user_data;
};
struct osmo_i460_subchan_mux {
/*! list of to-be-transmitted message buffers */
struct llist_head tx_queue;
};
struct osmo_i460_subchan {
enum osmo_i460_rate rate; /* 8/16/32/64k */
uint8_t bit_offset; /* bit offset inside each byte of the B-channel */
struct osmo_i460_subchan_demux demux;
struct osmo_i460_subchan_mux mux;
};
struct osmo_i460_timeslot {
struct osmo_i460_subchan schan[8];
};
/*! description of a sub-channel; passed by caller */
struct osmo_i460_schan_desc {
enum osmo_i460_rate rate;
uint8_t bit_offset;
struct {
/* size (in bits) of the internal buffer; determines granularity */
size_t num_bits;
/*! call-back function called whenever we received num_bits */
out_cb_bits_t out_cb_bits;
/*! out_cb_bytes call-back function called whenever we received num_bits.
* The user is usually expected to provide either out_cb_bits or out_cb_bytes. If only
* out_cb_bits is provided, output data will always be provided as unpacked bits; if only
* out_cb_bytes is provided, output data will always be provided as packet bits (bytes). If
* both are provided, it is up to the I.460 multiplex to decide if it calls either of the two,
* depending on what can be provided without extra conversion. */
out_cb_bytes_t out_cb_bytes;
/* opaque user data pointer to pass to out_cb */
void *user_data;
} demux;
};
void osmo_i460_demux_in(struct osmo_i460_timeslot *ts, const uint8_t *data, size_t data_len);
void osmo_i460_mux_enqueue(struct osmo_i460_subchan *schan, struct msgb *msg);
int osmo_i460_mux_out(struct osmo_i460_timeslot *ts, uint8_t *out, size_t out_len);
void osmo_i460_ts_init(struct osmo_i460_timeslot *ts);
struct osmo_i460_subchan *
osmo_i460_subchan_add(void *ctx, struct osmo_i460_timeslot *ts, const struct osmo_i460_schan_desc *chd);
void osmo_i460_subchan_del(struct osmo_i460_subchan *schan);
/*! @} */
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