laforge has submitted this change. ( 
https://gerrit.osmocom.org/c/libosmo-abis/+/18250 )

Change subject: Add new TRAU frame sync code
......................................................................

Add new TRAU frame sync code

This code is able to detect and sync against a variety of TRAU
frame sync patterns.  Focus is so far on those patterns present on
16k sub-slots, but 8k sub-slots are expected to be supported soon,
too.

A new codebase for this is required as the old OsmoNITB code had
conflated a 16k sub-slot multiplexer with TRAU frame synchronization,
so there was no way to separate those two parts and hence no way to
support 8k sub-slots.

Change-Id: Ia6fe6228b0b8b9a27999f37ce1115ed5558881ea
---
M include/Makefile.am
A include/osmocom/trau/trau_sync.h
M src/Makefile.am
A src/trau/trau_sync.c
A src/trau/ubit_buf.h
M tests/Makefile.am
M tests/testsuite.at
A tests/trau_sync/trau_sync_test.c
A tests/trau_sync/trau_sync_test.err
A tests/trau_sync/trau_sync_test.ok
10 files changed, 712 insertions(+), 4 deletions(-)

Approvals:
  laforge: Looks good to me, approved
  Jenkins Builder: Verified



diff --git a/include/Makefile.am b/include/Makefile.am
index aa735c5..2a99211 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -5,4 +5,5 @@
  osmocom/abis/subchan_demux.h osmocom/abis/e1_input.h                  \
  osmocom/abis/lapd.h osmocom/abis/lapd_pcap.h osmocom/trau/osmo_ortp.h \
  osmocom/abis/unixsocket_proto.h \
- osmocom/trau/trau_frame.h
+ osmocom/trau/trau_frame.h \
+ osmocom/trau/trau_sync.h
diff --git a/include/osmocom/trau/trau_sync.h b/include/osmocom/trau/trau_sync.h
new file mode 100644
index 0000000..46595be
--- /dev/null
+++ b/include/osmocom/trau/trau_sync.h
@@ -0,0 +1,19 @@
+#pragma once
+#include <osmocom/core/bits.h>
+#include <osmocom/core/fsm.h>
+
+enum osmo_tray_sync_pat_id {
+       OSMO_TRAU_SYNCP_16_FR_EFR,
+       OSMO_TRAU_SYNCP_8_HR,
+       OSMO_TRAU_SYNCP_8_AMR_LOW,
+       OSMO_TRAU_SYNCP_8_AMR_6K7,
+       OSMO_TRAU_SYNCP_8_AMR_7K4,
+};
+
+typedef void (*frame_out_cb_t)(void *user_data, const ubit_t *bits, unsigned 
int num_bits);
+
+struct osmo_fsm_inst *
+osmo_trau_sync_alloc(void *ctx, const char *name, frame_out_cb_t frame_out_cb,
+                    enum osmo_tray_sync_pat_id pat_id, void *user_data);
+
+void osmo_trau_sync_rx_ubits(struct osmo_fsm_inst *fi, const ubit_t *bits, 
size_t n_bits);
diff --git a/src/Makefile.am b/src/Makefile.am
index d1743af..0134b00 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -36,4 +36,7 @@
 libosmotrau_la_LDFLAGS = $(AM_LDFLAGS) -version-info $(TRAU_LIBVERSION)
 libosmotrau_la_LIBADD = $(COMMONLIBS) $(ORTP_LIBS)
 libosmotrau_la_SOURCES = trau/osmo_ortp.c \
-                        trau/trau_frame.c
+                        trau/trau_frame.c \
+                        trau/trau_sync.c
+
+noinst_HEADERS = trau/ubit_buf.h
diff --git a/src/trau/trau_sync.c b/src/trau/trau_sync.c
new file mode 100644
index 0000000..c4baad6
--- /dev/null
+++ b/src/trau/trau_sync.c
@@ -0,0 +1,522 @@
+/* GSM A-bis TRAU frame synchronization as per TS 48.060 / 48.061 */
+
+/* (C) 2020 by Harald Welte <[email protected]>
+ * All Rights Reserved
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdint.h>
+
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/bits.h>
+#include <osmocom/core/fsm.h>
+
+#include "ubit_buf.h"
+#include <osmocom/trau/trau_sync.h>
+
+#define S(x)   (1 << (x))
+
+#define MAX_TRAU_BYTES         40
+
+#define T_SYNC         1
+
+struct sync_pattern {
+       /* provided by user */
+       const char *name;                               /*!< human-readable 
name */
+       const uint8_t byte_pattern[MAX_TRAU_BYTES];     /*!< bytes to match 
against */
+       const uint8_t byte_mask[MAX_TRAU_BYTES];        /*!< mask applied 
before matching */
+       uint8_t byte_len;                               /*!< length of mask in 
bytes */
+
+       /* generated by code */
+       ubit_t ubit_pattern[MAX_TRAU_BYTES*8];          /*!< bits to match 
against */
+       ubit_t ubit_mask[MAX_TRAU_BYTES*8];             /*!< mask applied 
before matching */
+       uint8_t bitcount;                               /*!< number of high 
bits in mask */
+};
+
+static struct sync_pattern sync_patterns[] = {
+       [OSMO_TRAU_SYNCP_16_FR_EFR] = {
+               /* TS 08.60 Section 4.8.1 */
+               .name = "FR/EFR",
+               .byte_pattern = {
+                       0x00, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+               },
+               .byte_mask = {
+                       0xff, 0xff, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+               },
+               .byte_len = 40,
+       },
+       [OSMO_TRAU_SYNCP_8_HR] = {
+               /* TS 08.61 Section 6.8.2.1.1 */
+               .name = "HR8",
+               .byte_pattern = {
+                       0x00, 0x80, 0x40, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+               },
+               .byte_mask = {
+                       0xff, 0x80, 0xC0, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+               },
+               .byte_len = 20,
+       },
+       [OSMO_TRAU_SYNCP_8_AMR_LOW] = {
+               /* TS 08.61 Section 6.8.2.1.2 */
+               /* The frame synchronisation for No_Speech frames and the 
speech frames of the three lower codec modes */
+               .name = "AMR8_LOW",
+               .byte_pattern = {
+                       0x00, 0x80, 0x80, 0x40,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+               },
+               .byte_mask = {
+                       0xff, 0x80, 0x80, 0xC0,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x80,
+               },
+               .byte_len = 20,
+       },
+       [OSMO_TRAU_SYNCP_8_AMR_6K7] = {
+               /* The frame synchronisation for the speech frames for codec 
mode 6,70 kBit/s */
+               .name = "AMR8_67",
+               .byte_pattern = {
+                       0x00, 0x80, 0x80, 0x80,
+                       0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00,
+               },
+               .byte_mask = {
+                       0xff, 0x80, 0x80, 0x80,
+                       0x80, 0x80, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00,
+                       0x80, 0x00, 0x80, 0x00,
+               },
+               .byte_len = 20
+       },
+       [OSMO_TRAU_SYNCP_8_AMR_7K4] = {
+               /* The frame synchronisation for the speech frames for codec 
mode 7,40 kBit/s */
+               .name = "AMR8_74",
+               .byte_pattern = {
+                       0x20, 0x00, 0x80, 0x00,
+                       0x00, 0x00, 0x00, 0x00,
+                       0x00, 0x00, 0x00, 0x00,
+                       0x00, 0x00, 0x00, 0x00,
+                       0x00, 0x00, 0x00, 0x00,
+               },
+               .byte_mask = {
+                       0xe0, 0x80, 0x80, 0x80,
+                       0x00, 0x00, 0x00, 0x00,
+                       0x00, 0x00, 0x00, 0x00,
+                       0x00, 0x00, 0x00, 0x00,
+                       0x00, 0x00, 0x00, 0x00,
+               },
+               .byte_len = 20,
+       },
+};
+
+#if 0
+static struct sync_pattern rbs_ccu_sync_ind_16_pattern = {
+       .name ="RBS_CCU_SYNC_IND_16",
+       .byte_pattern = {
+               0x00, 0x00, 0x01, 0x00,
+               0x00, 0x00, 0x01, 0x00,
+               0x01, 0x00, 0x01, 0x00,
+       },
+       .byte_mask = {
+               0xff, 0xff, 0x01, 0x00,
+               0x01, 0x00, 0x01, 0x00,
+               0x01, 0x00, 0x01, 0x00,
+       },
+};
+
+static struct sync_pattern rbs_ccu_data_ind_16_pattern = {
+       .name ="RBS_CCU_DATA_IND_16",
+       .byte_pattern = {
+               0x00, 0x00, 0x01, 0x00,
+       },
+       .byte_mask = {
+               0xff, 0xff, 0x01, 0x00,
+       },
+};
+#endif
+
+
+static void expand_sync_pattern(struct sync_pattern *pat)
+{
+       osmo_pbit2ubit(pat->ubit_pattern, pat->byte_pattern, pat->byte_len*8);
+       osmo_pbit2ubit(pat->ubit_mask, pat->byte_mask, pat->byte_len*8);
+}
+
+static unsigned int count_one_bits(const ubit_t *in, unsigned int in_bits)
+{
+       unsigned int i, count = 0;
+
+       for (i = 0; i < in_bits; i++) {
+               if (in[i])
+                       count++;
+       }
+       return count;
+}
+
+static void sync_pattern_register(struct sync_pattern *p)
+{
+       expand_sync_pattern(p);
+       p->bitcount = count_one_bits(p->ubit_mask, p->byte_len*8);
+}
+
+#if 0
+/*! correlate pattern with unpacked bits from buffer.
+ *  \param[in] pattern sync_pattern against which we shall compare
+ *  \param[in] bits unpacked bits to compare against pattern
+ *  \param[in] num_bits number of unpacked bits
+ *  \returns number of bits not matching pattern; -1 if insufficient bits 
available. */
+static int correlate_pattern_ubits(const struct sync_pattern *pattern,
+                                   const ubit_t *bits, size_t num_bits)
+{
+       int i, num_wrong = 0;
+
+       if (num_bits < pattern->byte_len*8)
+               return -1; /* insufficient data */
+
+       for (i = 0; i < pattern->byte_len *8; i++) {
+               /* if mask doesn't contain '1', we can skip this octet */
+               if (!pattern->ubit_mask)
+                       continue;
+               if (bits[i] != pattern->ubit_pattern[i])
+                       num_wrong++;
+       }
+
+       return num_wrong;
+}
+#endif
+
+struct trau_rx_sync_state {
+       /*! call-back to be called for every TRAU frame (called with
+        * bits=NULL in case of frame sync loss */
+       frame_out_cb_t out_cb;
+       /*! opaque user data; passed to out_cb */
+       void *user_data;
+
+       /*! history of received bits */
+       ubit_t history[MAX_TRAU_BYTES*8+1]; /* +1 not required, but helps to 
expose bugs */
+       /*! index of next-to-be-written ubit in history */
+       unsigned int history_idx;
+       /*! the pattern we are trying to sync to */
+       const struct sync_pattern *pattern;
+       /*! number of consecutive frames without sync */
+       unsigned int num_consecutive_errors;
+};
+
+/* correlate the history (up to the last received bit) against the pattern */
+static int correlate_history_against_pattern(struct trau_rx_sync_state *tss)
+{
+       const struct sync_pattern *pattern = tss->pattern;
+       int i, start, num_wrong = 0;
+
+       /* compute index of first bit in history array */
+       start = (ARRAY_SIZE(tss->history) + tss->history_idx - 
pattern->byte_len*8)
+               % ARRAY_SIZE(tss->history);
+
+       OSMO_ASSERT(ARRAY_SIZE(tss->history) >= pattern->byte_len*8);
+
+       for (i = 0; i < pattern->byte_len*8; i++) {
+               unsigned int pos = (start + i) % ARRAY_SIZE(tss->history);
+
+               /* if mask doesn't contain '1', we can skip this octet */
+               if (!pattern->ubit_mask[i])
+                       continue;
+               if (tss->history[pos] != pattern->ubit_pattern[i])
+                       num_wrong++;
+       }
+
+       return num_wrong;
+}
+
+/* add (append) one ubit to the history; wrap as needed */
+static void rx_history_add_bit(struct trau_rx_sync_state *tss, ubit_t bit)
+{
+       tss->history[tss->history_idx] = bit;
+       /* simply wrap around at the end */
+       tss->history_idx = (tss->history_idx + 1) % ARRAY_SIZE(tss->history);
+}
+
+/* append bits to history. We assume that this does NOT wrap */
+static void rx_history_add_bits(struct trau_rx_sync_state *tss, const ubit_t 
*bits, size_t n_bits)
+{
+       unsigned int frame_bits_remaining = tss->pattern->byte_len*8 - 
tss->history_idx;
+       OSMO_ASSERT(frame_bits_remaining >= n_bits);
+       memcpy(&tss->history[tss->history_idx], bits, n_bits);
+       tss->history_idx = tss->history_idx + n_bits;
+}
+
+/* align the history, i.e. next received bit is start of frame */
+static void rx_history_align(struct trau_rx_sync_state *tss)
+{
+       ubit_t tmp[sizeof(tss->history)];
+       size_t history_size = sizeof(tss->history);
+       size_t pattern_bits = tss->pattern->byte_len*8;
+       size_t first_bit = (history_size + tss->history_idx - pattern_bits) % 
history_size;
+       int i;
+
+       /* we need to shift the last received frame to the start of the history 
buffer;
+        * do this in two steps: First copy to a local buffer on the stack, 
using modulo-arithmetic
+        * as index into the history.  Second, copy it back to history */
+
+       for (i = 0; i < pattern_bits; i++)
+               tmp[i] = tss->history[(first_bit + i) % history_size];
+
+       memcpy(tss->history, tmp, history_size);
+       tss->history_idx = 0;
+}
+
+enum trau_sync_state {
+       WAIT_FRAME_ALIGN,
+       FRAME_ALIGNED,
+       /* if at least 3 consecutive frames with each at least one framing 
error have been received */
+       FRAME_ALIGNMENT_LOST,
+};
+
+enum trau_sync_event {
+       TRAUSYNC_E_RESET,
+       /*! a buffer of bits was received (msgb with ubits) */
+       TRAUSYNC_E_RX_BITS,
+};
+
+static const struct value_string trau_sync_event_names[] = {
+       { TRAUSYNC_E_RESET, "RESET" },
+       { TRAUSYNC_E_RX_BITS, "RX_BITS" },
+       { 0, NULL }
+};
+
+
+static void trau_sync_wait_align(struct osmo_fsm_inst *fi, uint32_t event, 
void *data)
+{
+       struct trau_rx_sync_state *tss = (struct trau_rx_sync_state *) fi->priv;
+       struct ubit_buf *ubb;
+
+       switch (event) {
+       case TRAUSYNC_E_RX_BITS:
+               ubb = data;
+               /* append every bit individually + check if we have sync */
+               while (ubb_length(ubb) > 0) {
+                       ubit_t bit = ubb_pull_ubit(ubb);
+                       int rc;
+
+                       rx_history_add_bit(tss, bit);
+                       rc = correlate_history_against_pattern(tss);
+                       if (!rc) {
+                               osmo_fsm_inst_state_chg(fi, FRAME_ALIGNED, 0, 
0);
+                               /* treat remainder of input bits in correct 
state */
+                               osmo_fsm_inst_dispatch(fi, TRAUSYNC_E_RX_BITS, 
ubb);
+                               return;
+                       }
+               }
+               break;
+       default:
+               OSMO_ASSERT(0);
+       }
+}
+
+static void trau_sync_aligned_onenter(struct osmo_fsm_inst *fi, uint32_t 
prev_state)
+{
+       struct trau_rx_sync_state *tss = (struct trau_rx_sync_state *) fi->priv;
+       /* dispatch aligned frame to user */
+       rx_history_align(tss);
+       tss->out_cb(tss->user_data, tss->history, tss->pattern->byte_len*8);
+}
+
+static void trau_sync_aligned(struct osmo_fsm_inst *fi, uint32_t event, void 
*data)
+{
+       struct trau_rx_sync_state *tss = (struct trau_rx_sync_state *) fi->priv;
+       struct ubit_buf *ubb;
+       int rc;
+
+       switch (event) {
+       case TRAUSYNC_E_RX_BITS:
+               ubb = data;
+               while (ubb_length(ubb)) {
+                       unsigned int frame_bits_remaining = 
tss->pattern->byte_len*8 - tss->history_idx;
+                       if (ubb_length(ubb) < frame_bits_remaining) {
+                               /* frame not filled by this message; just add 
data */
+                               rx_history_add_bits(tss, ubb_data(ubb), 
ubb_length(ubb));
+                               ubb_pull(ubb, ubb_length(ubb));
+                       } else {
+                               /* append as many bits as are missing in the 
current frame */
+                               rx_history_add_bits(tss, ubb_data(ubb), 
frame_bits_remaining);
+                               ubb_pull(ubb, frame_bits_remaining);
+
+                               /* check if we still have frame sync */
+                               rc = correlate_history_against_pattern(tss);
+                               if (rc > 0) {
+                                       tss->num_consecutive_errors++;
+                                       if (tss->num_consecutive_errors >= 3) {
+                                               tss->history_idx = 0;
+                                               /* send NULL frame to user */
+                                               tss->out_cb(tss->user_data, 
NULL, 0);
+                                               osmo_fsm_inst_state_chg(fi, 
FRAME_ALIGNMENT_LOST, 1, T_SYNC);
+                                               osmo_fsm_inst_dispatch(fi, 
TRAUSYNC_E_RX_BITS, ubb);
+                                               return;
+                                       }
+                               } else
+                                       tss->num_consecutive_errors = 0;
+
+                               /* dispatch aligned frame to user */
+                               tss->out_cb(tss->user_data, tss->history, 
tss->history_idx);
+                               tss->history_idx = 0;
+                       }
+               }
+               break;
+       default:
+               OSMO_ASSERT(0);
+       }
+}
+
+static void trau_sync_alignment_lost(struct osmo_fsm_inst *fi, uint32_t event, 
void *data)
+{
+       /* we try to restore sync for some amount of time before generating an 
error */
+
+       switch (event) {
+       case TRAUSYNC_E_RX_BITS:
+               trau_sync_wait_align(fi, event, data);
+               break;
+       default:
+               OSMO_ASSERT(0);
+       }
+}
+
+static void trau_sync_allstate(struct osmo_fsm_inst *fi, uint32_t event, void 
*data)
+{
+       switch (event) {
+       case TRAUSYNC_E_RESET:
+               osmo_fsm_inst_state_chg(fi, WAIT_FRAME_ALIGN, 0, 0);
+               break;
+       default:
+               OSMO_ASSERT(0);
+       }
+}
+
+static int trau_sync_timeout(struct osmo_fsm_inst *fi)
+{
+       switch (fi->T) {
+       case T_SYNC:
+               /* if Tsync expires before frame synchronization is
+                * again obtained the TRAU initiates sending of the
+                * urgent alarm pattern described in clause 4.10.2. */
+               osmo_fsm_inst_state_chg(fi, WAIT_FRAME_ALIGN, 0, 0);
+               break;
+       default:
+               OSMO_ASSERT(0);
+       }
+       return 0;
+}
+
+static const struct osmo_fsm_state trau_sync_states[] = {
+       [WAIT_FRAME_ALIGN] = {
+               .name = "WAIT_FRAME_ALIGN",
+               .in_event_mask = S(TRAUSYNC_E_RX_BITS),
+               .out_state_mask = S(FRAME_ALIGNED),
+               .action = trau_sync_wait_align,
+       },
+       [FRAME_ALIGNED] = {
+               .name = "FRAME_ALIGNED",
+               .in_event_mask = S(TRAUSYNC_E_RX_BITS),
+               .out_state_mask = S(FRAME_ALIGNMENT_LOST) | S(WAIT_FRAME_ALIGN),
+               .action = trau_sync_aligned,
+               .onenter = trau_sync_aligned_onenter,
+       },
+       [FRAME_ALIGNMENT_LOST] = {
+               .name = "FRAME_ALIGNMENT_LOST",
+               .in_event_mask = S(TRAUSYNC_E_RX_BITS),
+               .out_state_mask = S(WAIT_FRAME_ALIGN) | S(FRAME_ALIGNED),
+               .action = trau_sync_alignment_lost,
+       },
+};
+
+static struct osmo_fsm trau_sync_fsm = {
+       .name = "trau_sync",
+       .states = trau_sync_states,
+       .num_states = ARRAY_SIZE(trau_sync_states),
+       .allstate_event_mask = S(TRAUSYNC_E_RESET),
+       .allstate_action = trau_sync_allstate,
+       .timer_cb = trau_sync_timeout,
+       .log_subsys = DLGLOBAL,
+       .event_names = trau_sync_event_names,
+};
+
+
+struct osmo_fsm_inst *
+osmo_trau_sync_alloc(void *ctx, const char *name, frame_out_cb_t frame_out_cb,
+                    enum osmo_tray_sync_pat_id pat_id, void *user_data)
+{
+       struct trau_rx_sync_state *tss;
+       struct osmo_fsm_inst *fi;
+
+       if (pat_id >= ARRAY_SIZE(sync_patterns))
+               return NULL;
+
+       fi = osmo_fsm_inst_alloc(&trau_sync_fsm, ctx, NULL, LOGL_NOTICE, name);
+       if (!fi)
+               return NULL;
+       tss = talloc_zero(fi, struct trau_rx_sync_state);
+       if (!tss) {
+               osmo_fsm_inst_term(fi, OSMO_FSM_TERM_ERROR, NULL);
+               return NULL;
+       }
+       fi->priv = tss;
+
+       tss->out_cb = frame_out_cb;
+       tss->user_data = user_data;
+       /* FIXME: this must be configurable */
+       tss->pattern = &sync_patterns[pat_id];
+
+       return fi;
+}
+
+void osmo_trau_sync_rx_ubits(struct osmo_fsm_inst *fi, const ubit_t *bits, 
size_t n_bits)
+{
+       struct ubit_buf ubb;
+       ubb_init(&ubb, bits, n_bits);
+       osmo_fsm_inst_dispatch(fi, TRAUSYNC_E_RX_BITS, &ubb);
+}
+
+static void __attribute__((constructor)) on_dso_load_sync(void)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(sync_patterns); i++)
+               sync_pattern_register(&sync_patterns[i]);
+       osmo_fsm_register(&trau_sync_fsm);
+}
diff --git a/src/trau/ubit_buf.h b/src/trau/ubit_buf.h
new file mode 100644
index 0000000..224b44b
--- /dev/null
+++ b/src/trau/ubit_buf.h
@@ -0,0 +1,42 @@
+#pragma once
+#include <osmocom/core/bits.h>
+
+/* Small helper inspired by msgb */
+
+struct ubit_buf {
+       const ubit_t *buf;      /*!< start of underlying buffer */
+       const ubit_t *data;     /*!< next to be consumed bit */
+       size_t n_bits;          /*!< number of total bits iin buffer */
+};
+
+/*! length of [remainig, to be processed] data in ubit_buf */
+static inline size_t ubb_length(struct ubit_buf *ubb)
+{
+       return ubb->n_bits - (ubb->data - ubb->buf);
+}
+
+/*! retrieve + remove a single ubit_t from start of ubit_buf */
+static inline ubit_t ubb_pull_ubit(struct ubit_buf *ubb)
+{
+       OSMO_ASSERT(ubb->data < ubb->buf + ubb->n_bits);
+       return *ubb->data++;
+}
+
+static inline void ubb_pull(struct ubit_buf *ubb, size_t count)
+{
+       OSMO_ASSERT(ubb_length(ubb) >= count);
+       ubb->data += count;
+}
+
+/*! get pointer to next to be consumed bit */
+static inline const ubit_t *ubb_data(struct ubit_buf *ubb)
+{
+       return ubb->data;
+}
+
+static inline void ubb_init(struct ubit_buf *ubb, const ubit_t *bits, size_t 
n_bits)
+{
+       ubb->buf = bits;
+       ubb->data = ubb->buf;
+       ubb->n_bits = n_bits;
+}
diff --git a/tests/Makefile.am b/tests/Makefile.am
index bd95cf5..dcd9a4f 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -7,7 +7,8 @@
                  ipa_proxy_test        \
                  subchan_demux/subchan_demux_test \
                  ipa_recv/ipa_recv_test \
-                 rtp_test/rtp_test
+                 rtp_test/rtp_test \
+                 trau_sync/trau_sync_test

 e1inp_ipa_bsc_test_SOURCES = e1inp_ipa_bsc_test.c
 e1inp_ipa_bsc_test_LDADD = $(top_builddir)/src/libosmoabis.la \
@@ -36,6 +37,10 @@
 rtp_test_rtp_test_LDADD = $(top_builddir)/src/libosmotrau.la \
                        $(LIBOSMOCORE_LIBS)

+trau_sync_trau_sync_test_SOURCES = trau_sync/trau_sync_test.c
+trau_sync_trau_sync_test_LDADD = $(top_builddir)/src/libosmotrau.la \
+                       $(LIBOSMOCORE_LIBS)
+

 # boilerplate for the tests
 # The `:;' works around a Bash 3.2 bug when the output is not writeable.
@@ -59,7 +64,8 @@
 EXTRA_DIST = testsuite.at $(srcdir)/package.m4 $(TESTSUITE) \
        subchan_demux/subchan_demux_test.ok \
        ipa_recv/ipa_recv_test.ok \
-       rtp_test/rtp_test.ok
+       rtp_test/rtp_test.ok \
+       trau_sync/trau_sync_test.ok trau_sync/trau_sync_test.err

 TESTSUITE = $(srcdir)/testsuite

diff --git a/tests/testsuite.at b/tests/testsuite.at
index 5e87248..4faf429 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -29,3 +29,9 @@
 AT_CHECK([$abs_top_builddir/tests/rtp_test/rtp_test], [ignore], [expout])
 AT_CLEANUP

+AT_SETUP([trau_sync])
+AT_KEYWORDS([trau_sync])
+cat $abs_srcdir/trau_sync/trau_sync_test.ok > expout
+cat $abs_srcdir/trau_sync/trau_sync_test.err > experr
+AT_CHECK([$abs_top_builddir/tests/trau_sync/trau_sync_test], [0], [expout], 
[experr])
+AT_CLEANUP
diff --git a/tests/trau_sync/trau_sync_test.c b/tests/trau_sync/trau_sync_test.c
new file mode 100644
index 0000000..392a236
--- /dev/null
+++ b/tests/trau_sync/trau_sync_test.c
@@ -0,0 +1,85 @@
+
+#include <osmocom/core/application.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/bits.h>
+
+#include <osmocom/trau/trau_sync.h>
+
+static void frame_out_cb(void *user_data, const ubit_t *bits, unsigned int 
num_bits)
+{
+       char *str = user_data;
+       printf("demux_bits_cb '%s': %s\n", str, osmo_ubit_dump(bits, num_bits));
+}
+
+static const uint8_t sync_pattern[] = {
+       0x00, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+       0x80, 0x00, 0x80, 0x00, 0x80, 0x00, 0x80, 0x00,
+};
+
+#define ASSERT_STATE(fi, x) OSMO_ASSERT(!strcmp(osmo_fsm_inst_state_name(fi), 
x))
+
+static void test_body(void)
+{
+       struct osmo_fsm_inst *fi = osmo_trau_sync_alloc(NULL, "test", 
frame_out_cb, OSMO_TRAU_SYNCP_16_FR_EFR, "test");
+       OSMO_ASSERT(fi);
+
+       printf("\n==> %s\n", __func__);
+
+       ubit_t bits[40*8];
+
+       /* send some invalid data */
+       memset(bits, 0, sizeof(bits));
+       osmo_trau_sync_rx_ubits(fi, bits, sizeof(bits));
+       osmo_trau_sync_rx_ubits(fi, bits, 23);
+
+       /* first valid frame */
+       osmo_pbit2ubit(bits, sync_pattern, sizeof(sync_pattern)*8);
+       osmo_trau_sync_rx_ubits(fi, bits, sizeof(bits));
+       ASSERT_STATE(fi, "FRAME_ALIGNED");
+
+       /* second valid frame */
+       osmo_trau_sync_rx_ubits(fi, bits, sizeof(bits));
+       ASSERT_STATE(fi, "FRAME_ALIGNED");
+
+       /* send wrong frame */
+       memset(bits, 1, sizeof(bits));
+       osmo_trau_sync_rx_ubits(fi, bits, sizeof(bits));
+       ASSERT_STATE(fi, "FRAME_ALIGNED");
+
+       /* intersperse a valid frame */
+       osmo_pbit2ubit(bits, sync_pattern, sizeof(sync_pattern)*8);
+       osmo_trau_sync_rx_ubits(fi, bits, sizeof(bits));
+
+       /* second wrong frame - but not consecutive */
+       memset(bits, 1, sizeof(bits));
+       osmo_trau_sync_rx_ubits(fi, bits, sizeof(bits));
+       ASSERT_STATE(fi, "FRAME_ALIGNED");
+
+       /* third wrong frame - second consecutive */
+       osmo_trau_sync_rx_ubits(fi, bits, sizeof(bits));
+       ASSERT_STATE(fi, "FRAME_ALIGNED");
+
+       /* only from third consecutive invalid frame onwards we should loose 
alignment */
+       osmo_trau_sync_rx_ubits(fi, bits, sizeof(bits));
+       ASSERT_STATE(fi, "FRAME_ALIGNMENT_LOST");
+}
+
+
+static const struct log_info_cat default_categories[] = {
+};
+
+const struct log_info log_info = {
+       .cat = default_categories,
+       .num_cat = ARRAY_SIZE(default_categories),
+};
+
+int main(int argc, char **argv)
+{
+       osmo_init_logging2(NULL, NULL);
+       osmo_fsm_log_addr(false);
+       log_set_print_filename2(osmo_stderr_target, LOG_FILENAME_NONE);
+       test_body();
+}
diff --git a/tests/trau_sync/trau_sync_test.err 
b/tests/trau_sync/trau_sync_test.err
new file mode 100644
index 0000000..f3eac3c
--- /dev/null
+++ b/tests/trau_sync/trau_sync_test.err
@@ -0,0 +1,15 @@
+<0000> trau_sync(test){WAIT_FRAME_ALIGN}: Allocated
+<0000> trau_sync(test){WAIT_FRAME_ALIGN}: Received Event RX_BITS
+<0000> trau_sync(test){WAIT_FRAME_ALIGN}: Received Event RX_BITS
+<0000> trau_sync(test){WAIT_FRAME_ALIGN}: Received Event RX_BITS
+<0000> trau_sync(test){WAIT_FRAME_ALIGN}: state_chg to FRAME_ALIGNED
+<0000> trau_sync(test){FRAME_ALIGNED}: Received Event RX_BITS
+<0000> trau_sync(test){FRAME_ALIGNED}: Received Event RX_BITS
+<0000> trau_sync(test){FRAME_ALIGNED}: Received Event RX_BITS
+<0000> trau_sync(test){FRAME_ALIGNED}: Received Event RX_BITS
+<0000> trau_sync(test){FRAME_ALIGNED}: Received Event RX_BITS
+<0000> trau_sync(test){FRAME_ALIGNED}: Received Event RX_BITS
+<0000> trau_sync(test){FRAME_ALIGNED}: Received Event RX_BITS
+<0000> trau_sync(test){FRAME_ALIGNED}: state_chg to FRAME_ALIGNMENT_LOST
+<0000> trau_sync(test){FRAME_ALIGNMENT_LOST}: Received Event RX_BITS
+
\ No newline at end of file
diff --git a/tests/trau_sync/trau_sync_test.ok 
b/tests/trau_sync/trau_sync_test.ok
new file mode 100644
index 0000000..2555913
--- /dev/null
+++ b/tests/trau_sync/trau_sync_test.ok
@@ -0,0 +1,9 @@
+
+==> test_body
+demux_bits_cb 'test': 
00000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000
+demux_bits_cb 'test': 
00000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000
+demux_bits_cb 'test': 
11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
+demux_bits_cb 'test': 
00000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000100000000000000010000000000000001000000000000000
+demux_bits_cb 'test': 
11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
+demux_bits_cb 'test': 
11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
+demux_bits_cb 'test':

--
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Gerrit-Project: libosmo-abis
Gerrit-Branch: master
Gerrit-Change-Id: Ia6fe6228b0b8b9a27999f37ce1115ed5558881ea
Gerrit-Change-Number: 18250
Gerrit-PatchSet: 12
Gerrit-Owner: laforge <[email protected]>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: laforge <[email protected]>
Gerrit-MessageType: merged

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