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Diffstat (limited to 'include/osmocom/isdn/i460_mux.h')
| -rw-r--r-- | include/osmocom/isdn/i460_mux.h | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/include/osmocom/isdn/i460_mux.h b/include/osmocom/isdn/i460_mux.h new file mode 100644 index 00000000..537e3257 --- /dev/null +++ b/include/osmocom/isdn/i460_mux.h @@ -0,0 +1,120 @@ +/*! \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. + */ + +#pragma once +#include <stdint.h> +#include <osmocom/core/bits.h> +#include <osmocom/core/linuxlist.h> +#include <osmocom/core/msgb.h> + +#define OSMO_I460_NUM_SUBCHAN 8 + +/* 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, +}; + +struct osmo_i460_subchan; + +typedef void (*out_cb_bits_t)(struct osmo_i460_subchan *schan, void *user_data, + const ubit_t *bits, unsigned int num_bits); +typedef void (*out_cb_bytes_t)(struct osmo_i460_subchan *schan, 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; +}; + +typedef void (*in_cb_queue_empty_t)(struct osmo_i460_subchan *schan, void *user_data); + +struct osmo_i460_subchan_mux { + /*! list of to-be-transmitted message buffers */ + struct llist_head tx_queue; + in_cb_queue_empty_t in_cb_queue_empty; + void *user_data; +}; + +struct osmo_i460_subchan { + struct osmo_i460_timeslot *ts; /* back-pointer */ + 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[OSMO_I460_NUM_SUBCHAN]; +}; + +/*! 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; + + struct { + /* call-back function whenever the muxer requires more input data from the sub-channels, + * but has nothing enqueued yet. A typical function would then call osmo_i460_mux_enqueue() */ + in_cb_queue_empty_t in_cb_queue_empty; + /* opaque user data pointer to pass to in_cb */ + void *user_data; + } mux; +}; + +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); + +int osmo_i460_subchan_count(struct osmo_i460_timeslot *ts); + +/*! @} */ |