diff options
Diffstat (limited to 'openbsc/src/libtrau/subchan_demux.c')
-rw-r--r-- | openbsc/src/libtrau/subchan_demux.c | 321 |
1 files changed, 0 insertions, 321 deletions
diff --git a/openbsc/src/libtrau/subchan_demux.c b/openbsc/src/libtrau/subchan_demux.c deleted file mode 100644 index 740d2caaf..000000000 --- a/openbsc/src/libtrau/subchan_demux.c +++ /dev/null @@ -1,321 +0,0 @@ -/* A E1 sub-channel (de)multiplexer with TRAU frame sync */ - -/* (C) 2009 by Harald Welte <laforge@gnumonks.org> - * All Rights Reserved - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU Affero General Public License as published by - * the Free Software Foundation; either version 3 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 Affero General Public License for more details. - * - * You should have received a copy of the GNU Affero General Public License - * along with this program. If not, see <http://www.gnu.org/licenses/>. - * - */ - -#include <unistd.h> -#include <stdlib.h> -#include <stdio.h> -#include <string.h> -#include <errno.h> - -#include <openbsc/subchan_demux.h> -#include <openbsc/trau_frame.h> -#include <openbsc/debug.h> -#include <osmocom/core/talloc.h> -#include <openbsc/gsm_data.h> - -void *tall_tqe_ctx; - -static inline void append_bit(struct demux_subch *sch, uint8_t bit) -{ - sch->out_bitbuf[sch->out_idx++] = bit; -} - -#define SYNC_HDR_BITS 16 -static const uint8_t nullbytes[SYNC_HDR_BITS]; - -/* check if we have just completed the 16 bit zero sync header, - * in accordance with GSM TS 08.60 Chapter 4.8.1 */ -static int sync_hdr_complete(struct demux_subch *sch, uint8_t bit) -{ - if (bit == 0) - sch->consecutive_zeros++; - else - sch->consecutive_zeros = 0; - - if (sch->consecutive_zeros >= SYNC_HDR_BITS) { - sch->consecutive_zeros = 0; - return 1; - } - - return 0; -} - -/* resynchronize to current location */ -static void resync_to_here(struct demux_subch *sch) -{ - memset(sch->out_bitbuf, 0, SYNC_HDR_BITS); - - /* set index in a way that we can continue receiving bits after - * the end of the SYNC header */ - sch->out_idx = SYNC_HDR_BITS; - sch->in_sync = 1; -} - -int subch_demux_init(struct subch_demux *dmx) -{ - int i; - - dmx->chan_activ = 0; - for (i = 0; i < NR_SUBCH; i++) { - struct demux_subch *sch = &dmx->subch[i]; - sch->out_idx = 0; - memset(sch->out_bitbuf, 0xff, sizeof(sch->out_bitbuf)); - } - return 0; -} - -/* input some arbitrary (modulo 4) number of bytes of a 64k E1 channel, - * split it into the 16k subchannels */ -int subch_demux_in(struct subch_demux *dmx, uint8_t *data, int len) -{ - int i, c; - - /* we avoid partially filled bytes in outbuf */ - if (len % 4) - return -EINVAL; - - for (i = 0; i < len; i++) { - uint8_t inbyte = data[i]; - - for (c = 0; c < NR_SUBCH; c++) { - struct demux_subch *sch = &dmx->subch[c]; - uint8_t inbits; - uint8_t bit; - - /* ignore inactive subchannels */ - if (!(dmx->chan_activ & (1 << c))) - continue; - - inbits = inbyte >> (c << 1); - - /* two bits for each subchannel */ - if (inbits & 0x01) - bit = 1; - else - bit = 0; - append_bit(sch, bit); - - if (sync_hdr_complete(sch, bit)) - resync_to_here(sch); - - if (inbits & 0x02) - bit = 1; - else - bit = 0; - append_bit(sch, bit); - - if (sync_hdr_complete(sch, bit)) - resync_to_here(sch); - - /* FIXME: verify the first bit in octet 2, 4, 6, ... - * according to TS 08.60 4.8.1 */ - - /* once we have reached TRAU_FRAME_BITS, call - * the TRAU frame handler callback function */ - if (sch->out_idx >= TRAU_FRAME_BITS) { - if (sch->in_sync) { - dmx->out_cb(dmx, c, sch->out_bitbuf, - sch->out_idx, dmx->data); - sch->in_sync = 0; - } - sch->out_idx = 0; - } - } - } - return i; -} - -int subch_demux_activate(struct subch_demux *dmx, int subch) -{ - if (subch >= NR_SUBCH) - return -EINVAL; - - dmx->chan_activ |= (1 << subch); - return 0; -} - -int subch_demux_deactivate(struct subch_demux *dmx, int subch) -{ - if (subch >= NR_SUBCH) - return -EINVAL; - - dmx->chan_activ &= ~(1 << subch); - return 0; -} - -/* MULTIPLEXER */ - -static int alloc_add_idle_frame(struct subch_mux *mx, int sch_nr) -{ - /* allocate and initialize with idle pattern */ - return subchan_mux_enqueue(mx, sch_nr, trau_idle_frame(), - TRAU_FRAME_BITS); -} - -/* return the requested number of bits from the specified subchannel */ -static int get_subch_bits(struct subch_mux *mx, int subch, - uint8_t *bits, int num_requested) -{ - struct mux_subch *sch = &mx->subch[subch]; - int num_bits = 0; - - while (num_bits < num_requested) { - struct subch_txq_entry *txe; - int num_bits_left; - int num_bits_thistime; - - /* make sure we have a valid entry at top of tx queue. - * if not, add an idle frame */ - if (llist_empty(&sch->tx_queue)) - alloc_add_idle_frame(mx, subch); - - if (llist_empty(&sch->tx_queue)) - return -EIO; - - txe = llist_entry(sch->tx_queue.next, struct subch_txq_entry, list); - num_bits_left = txe->bit_len - txe->next_bit; - - if (num_bits_left < num_requested) - num_bits_thistime = num_bits_left; - else - num_bits_thistime = num_requested; - - /* pull the bits from the txe */ - memcpy(bits + num_bits, txe->bits + txe->next_bit, num_bits_thistime); - txe->next_bit += num_bits_thistime; - - /* free the tx_queue entry if it is fully consumed */ - if (txe->next_bit >= txe->bit_len) { - llist_del(&txe->list); - talloc_free(txe); - } - - /* increment global number of bits dequeued */ - num_bits += num_bits_thistime; - } - - return num_requested; -} - -/* compact an array of 8 single-bit bytes into one byte of 8 bits */ -static uint8_t compact_bits(const uint8_t *bits) -{ - uint8_t ret = 0; - int i; - - for (i = 0; i < 8; i++) - ret |= (bits[i] ? 1 : 0) << i; - - return ret; -} - -/* obtain a single output byte from the subchannel muxer */ -static int mux_output_byte(struct subch_mux *mx, uint8_t *byte) -{ - uint8_t bits[8]; - int rc; - - /* combine two bits of every subchan */ - rc = get_subch_bits(mx, 0, &bits[0], 2); - rc = get_subch_bits(mx, 1, &bits[2], 2); - rc = get_subch_bits(mx, 2, &bits[4], 2); - rc = get_subch_bits(mx, 3, &bits[6], 2); - - *byte = compact_bits(bits); - - return rc; -} - -/* Request the output of some muxed bytes from the subchan muxer */ -int subchan_mux_out(struct subch_mux *mx, uint8_t *data, int len) -{ - int i; - - for (i = 0; i < len; i++) { - int rc; - rc = mux_output_byte(mx, &data[i]); - if (rc < 0) - break; - } - return i; -} - -static int llist_len(struct llist_head *head) -{ - struct llist_head *entry; - int i = 0; - - llist_for_each(entry, head) - i++; - - return i; -} - -/* evict the 'num_evict' number of oldest entries in the queue */ -static void tx_queue_evict(struct mux_subch *sch, int num_evict) -{ - struct subch_txq_entry *tqe; - int i; - - for (i = 0; i < num_evict; i++) { - if (llist_empty(&sch->tx_queue)) - return; - - tqe = llist_entry(sch->tx_queue.next, struct subch_txq_entry, list); - llist_del(&tqe->list); - talloc_free(tqe); - } -} - -/* enqueue some data into the tx_queue of a given subchannel */ -int subchan_mux_enqueue(struct subch_mux *mx, int s_nr, const uint8_t *data, - int len) -{ - struct mux_subch *sch = &mx->subch[s_nr]; - int list_len = llist_len(&sch->tx_queue); - struct subch_txq_entry *tqe = talloc_zero_size(tall_tqe_ctx, - sizeof(*tqe) + len); - if (!tqe) - return -ENOMEM; - - tqe->bit_len = len; - memcpy(tqe->bits, data, len); - - if (list_len > 2) - tx_queue_evict(sch, list_len-2); - - llist_add_tail(&tqe->list, &sch->tx_queue); - - return 0; -} - -/* initialize one subchannel muxer instance */ -int subchan_mux_init(struct subch_mux *mx) -{ - int i; - - memset(mx, 0, sizeof(*mx)); - for (i = 0; i < NR_SUBCH; i++) { - struct mux_subch *sch = &mx->subch[i]; - INIT_LLIST_HEAD(&sch->tx_queue); - } - - return 0; -} |