diff options
author | Harald Welte <laforge@gnumonks.org> | 2009-02-09 18:13:26 +0000 |
---|---|---|
committer | Harald Welte <laforge@gnumonks.org> | 2009-02-09 18:13:26 +0000 |
commit | 1fa60c8ab04653bae5ac29d8d93ad18b44f0f354 (patch) | |
tree | 35aa1e0c66c605576bb900347c465e9120a85fc0 /src/subchan_demux.c | |
parent | 0b4c34e3ca22da724de308b8154a2730b53fc388 (diff) |
* add trau_mux implementation to relay from one incoming TRAU
channel to another one (simple voice call switching)
* add a way more generic E1 input layer, abstracting out the misdn
low-level interface. This also adds infrastructure for multiple TRX
in one BTS, as well as multiple BTS on one E1 link
* add a E1 subchannel multiplexer for sending multiple 16kbit sub-channels
one one 64kBps E1 channel
* add TRAU IDLE frame generation
* terminate bsc_hack in case there is a E1 / mISDN init error
* introduce 'e1_config.c' file with static configuration of our
E1 setup (which TRX/BTS is configured for which TEI/SAPI/E1). This should
later become a config file rather than a compiled C file.
WARNING: all this compiles but is not tested yet. Expect fix-up committs over
the next hours or so
Diffstat (limited to 'src/subchan_demux.c')
-rw-r--r-- | src/subchan_demux.c | 144 |
1 files changed, 138 insertions, 6 deletions
diff --git a/src/subchan_demux.c b/src/subchan_demux.c index da1b09072..78ba2dae2 100644 --- a/src/subchan_demux.c +++ b/src/subchan_demux.c @@ -1,4 +1,4 @@ -/* A E1 sub-channel demultiplexer with TRAU frame sync */ +/* A E1 sub-channel (de)multiplexer with TRAU frame sync */ /* (C) 2009 by Harald Welte <laforge@gnumonks.org> * All Rights Reserved @@ -26,8 +26,9 @@ #include <errno.h> #include <openbsc/subchan_demux.h> +#include <openbsc/trau_frame.h> -static inline void append_bit(struct subch *sch, u_int8_t bit) +static inline void append_bit(struct demux_subch *sch, u_int8_t bit) { sch->out_bitbuf[sch->out_idx++] = bit; } @@ -37,7 +38,7 @@ static const u_int8_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 subch *sch) +static int sync_hdr_complete(struct demux_subch *sch) { int rc; int bits_at_end = 0; @@ -62,7 +63,7 @@ static int sync_hdr_complete(struct subch *sch) } /* resynchronize to current location */ -static void resync_to_here(struct subch *sch) +static void resync_to_here(struct demux_subch *sch) { #if 0 u_int8_t tmp[TRAU_FRAME_BITS]; @@ -98,7 +99,7 @@ int subch_demux_init(struct subch_demux *dmx) dmx->chan_activ = 0; for (i = 0; i < NR_SUBCH; i++) { - struct subch *sch = &dmx->subch[i]; + struct demux_subch *sch = &dmx->subch[i]; sch->out_idx = 0; memset(sch->out_bitbuf, 0xff, sizeof(sch->out_bitbuf)); } @@ -119,7 +120,7 @@ int subch_demux_in(struct subch_demux *dmx, u_int8_t *data, int len) u_int8_t inbyte = data[i]; for (c = 0; c < NR_SUBCH; c++) { - struct subch *sch = &dmx->subch[c]; + struct demux_subch *sch = &dmx->subch[c]; u_int8_t bit; /* ignore inactive subchannels */ @@ -177,3 +178,134 @@ int subch_demux_deactivate(struct subch_demux *dmx, int subch) dmx->chan_activ &= ~(1 << subch); return 0; } + +/* MULTIPLEXER */ + +static int alloc_add_idle_frame(struct subch_mux *mx, int sch_nr) +{ + /* FIXME: 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, + u_int8_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, 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_requested); + 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); + 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 u_int8_t compact_bits(u_int8_t *bits) +{ + u_int8_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, u_int8_t *byte) +{ + u_int8_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); + + if (!rc) + *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, u_int8_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; +} + +/* enqueue some data into the tx_queue of a given subchannel */ +int subchan_mux_enqueue(struct subch_mux *mx, int s_nr, const u_int8_t *data, + int len) +{ + struct mux_subch *sch = &mx->subch[s_nr]; + struct subch_txq_entry *tqe = malloc(sizeof(*tqe) + len); + + if (!tqe) + return -ENOMEM; + + memset(tqe, 0, sizeof(*tqe)); + tqe->bit_len = len; + memcpy(tqe->bits, data, len); + + llist_add(&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; +} |