rename osmo_e1 to osmo_e1f ("f" for "framer")
diff --git a/src/osmo_e1f.c b/src/osmo_e1f.c
new file mode 100644
index 0000000..5ea6d54
--- /dev/null
+++ b/src/osmo_e1f.c
@@ -0,0 +1,699 @@
+/* Osmocom Software Defined E1
+ *
+ * (C) 2018 by Harald Welte <laforge@gnumonks.org>
+ *
+ * Implements ITU-T Rec. G.704 Section 2.3
+ */
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/fsm.h>
+
+#include "crc4itu.h"
+#include "osmo_e1f.h"
+
+#define S(x) (1 << (x))
+
+/* Frame Alignment Signal (BIT1 may be overwritten with CRC-4) */
+#define G704_E1_FAS 0x1B
+
+static inline bool is_correct_fas(uint8_t bt) {
+ if ((bt & 0x7F) == G704_E1_FAS)
+ return true;
+ else
+ return false;
+}
+
+/* are we in SMF II (true) or I (false) */
+static inline bool is_smf_II(const struct osmo_e1f_tx_state *tx) {
+ if (tx->frame_nr >= 8)
+ return true;
+ return false;
+}
+
+static struct osmo_fsm e1_align_fsm;
+static void align_fsm_reset(struct osmo_e1f_instance *e1i);
+
+static void notify_user(struct osmo_e1f_instance *e1i, enum osmo_e1f_notify_event evt,
+ bool present, void *priv)
+{
+ if (!e1i->notify_cb)
+ return;
+ e1i->notify_cb(e1i, evt, present, priv);
+}
+
+/*! Initialize a (caller-allocated) Osmocom E1 Instance
+ * \param[inout] e1i E1 Instance to be initialized
+ * \returns 0 on success, negative on error */
+int osmo_e1f_instance_init(struct osmo_e1f_instance *e1i, const char *name, e1_notify_cb cb,
+ bool crc4_enabled, void *priv)
+{
+ int i;
+
+ e1i->crc4_enabled = crc4_enabled;
+ e1i->notify_cb = cb;
+ e1i->tx.sa4_sa8 = 0x00;
+
+ e1i->priv = priv;
+
+ for (i = 1; i < ARRAY_SIZE(e1i->ts); i++) {
+ struct osmo_e1f_instance_ts *e1t = &e1i->ts[i];
+ e1t->ts_nr = i;
+ e1t->inst = e1i;
+ INIT_LLIST_HEAD(&e1t->tx.queue);
+
+ e1t->rx.granularity = 256;
+ }
+
+ e1i->rx.fi = osmo_fsm_inst_alloc(&e1_align_fsm, NULL, e1i, LOGL_DEBUG, name);
+ if (!e1i->rx.fi)
+ return -1;
+
+ osmo_e1f_instance_reset(e1i);
+
+ return 0;
+}
+
+/*! stop E1 timeslot; release any pending rx/tx buffers
+ * \param[in] e1t Timeslot which we are to stop, disable and release buffers */
+void osmo_e1f_ts_reset(struct osmo_e1f_instance_ts *e1t)
+{
+ e1t->tx.underruns = 0;
+ msgb_queue_free(&e1t->tx.queue);
+
+ e1t->rx.enabled = false;
+ msgb_free(e1t->rx.msg);
+ e1t->rx.msg = NULL;
+
+ osmo_isdnhdlc_rcv_init(&e1t->rx.hdlc, OSMO_HDLC_F_BITREVERSE);
+ //osmo_isdnhdlc_rcv_init(&e1t->rx.hdlc, 0);
+ osmo_isdnhdlc_out_init(&e1t->tx.hdlc, 0);
+}
+
+/*! stop E1 instance; stops all timeslots and releases any pending rx/tx buffers
+ * \param[in] e1t E1 instance which we are to stop */
+void osmo_e1f_instance_reset(struct osmo_e1f_instance *e1i)
+{
+ int i;
+
+ align_fsm_reset(e1i);
+
+ e1i->tx.remote_alarm = false;
+ e1i->tx.crc4_error = false;
+ e1i->tx.frame_nr = 0;
+ e1i->tx.crc4_last_smf = 0;
+ e1i->tx.crc4 = crc4itu_init();
+
+ e1i->rx.frame_nr = 0;
+ memset(&e1i->rx.ts0_history, 0, sizeof(e1i->rx.ts0_history));
+ e1i->rx.ts0_hist_len = 0;
+ e1i->rx.remote_alarm = false;
+ e1i->rx.remote_crc4_error = false;
+ e1i->rx.num_ts0_in_mframe_search = 0;
+
+ for (i = 1; i < ARRAY_SIZE(e1i->ts); i++) {
+ struct osmo_e1f_instance_ts *e1t = &e1i->ts[i];
+ osmo_e1f_ts_reset(e1t);
+ }
+}
+
+/*! obtain pointer to TS given by instance + timeslot number
+ * \param[in] e1i E1 intance on which we work
+ * \param[in] ts_nr E1 timeslot number (1..31)
+ * \returns pointer to timeslot; NULL on error */
+struct osmo_e1f_instance_ts *osmo_e1f_instance_ts(struct osmo_e1f_instance *e1i, uint8_t ts_nr)
+{
+ if (ts_nr == 0 || ts_nr >= ARRAY_SIZE(e1i->ts))
+ return NULL;
+
+ return &e1i->ts[ts_nr];
+}
+
+/*! configure an E1 timeslot
+ * \param[in] e1t Timeslot which we are to configure
+ * \param[in] granularity granularity (buffer size) to use on Rx
+ * \param[in] enable enable (true) or disalble (false) receiving on this TS
+ * \param[in] mode the mode for this timeslot (raw or hdlc)
+ * \return 0 on success; negative on error */
+int osmo_e1f_ts_config(struct osmo_e1f_instance_ts *e1t, e1_data_cb cb, unsigned int granularity,
+ bool enable, enum osmo_e1f_ts_mode mode)
+{
+ e1t->rx.data_cb = cb;
+ e1t->rx.enabled = enable;
+ e1t->rx.granularity = granularity;
+ e1t->mode = mode;
+
+ return 0;
+}
+
+const struct value_string osmo_e1f_notifv_evt_names[] = {
+ { E1_NTFY_EVT_ALIGN_FRAME, "Aligned to Frame" },
+ { E1_NTFY_EVT_ALIGN_CRC_MFRAME, "Aligned to CRC4-Multiframe" },
+ { E1_NTFY_EVT_CRC_ERROR, "CRC Error detected (local)" },
+ { E1_NTFY_EVT_REMOTE_CRC_ERROR, "CRC Error reported (remote)" },
+ { E1_NTFY_EVT_REMOTE_ALARM, "Remote Alarm condition repoorted" },
+ { 0, NULL }
+};
+
+/***********************************************************************
+ * Transmit Side
+ ***********************************************************************/
+
+/*! Enqueue a message buffer of to-be-transmitted data for a timeslot
+ * \param[in] e1i E1 instance for which to enqueue
+ * \param[in] ts_nr Timeslot number on which data is to be transmitted
+ * \param[in] msg Message buffer storing the to-be-transmitted data
+ * \returns 0 on success; negative in case of error.
+ *
+ * Ownership of \a msg is transferred from caller into this function, but only
+ * in case of successful execution (return 0)!
+ */
+void osmo_e1f_ts_enqueue(struct osmo_e1f_instance_ts *e1t, struct msgb *msg)
+{
+ msgb_enqueue(&e1t->tx.queue, msg);
+}
+
+/* obtain a CRC4 bit for the current frame number */
+static uint8_t e1_pull_crc4_bit(struct osmo_e1f_instance *e1i)
+{
+ /* If CRC-4 is disabled, all CRC bits shall be '1' */
+ if (e1i->crc4_enabled == 0) {
+ return 0x01;
+ } else {
+ /* CRC is transmitted MSB first */
+ switch (e1i->tx.frame_nr % 8) {
+ case 0:
+ return (e1i->tx.crc4_last_smf >> 3) & 1;
+ case 2:
+ return (e1i->tx.crc4_last_smf >> 2) & 1;
+ case 4:
+ return (e1i->tx.crc4_last_smf >> 1) & 1;
+ case 6:
+ return (e1i->tx.crc4_last_smf >> 0) & 1;
+ default:
+ OSMO_ASSERT(0);
+ }
+ }
+}
+
+/* pull a single to-be-transmitted byte for TS0 */
+static uint8_t e1_pull_ts0(struct osmo_e1f_instance *e1i)
+{
+ uint8_t ret;
+
+ /* according to Table 5B/G.704 - CRC-4 multiframe structure */
+ if ((e1i->tx.frame_nr % 2) == 0) {
+ /* FAS */
+ ret = G704_E1_FAS | (e1_pull_crc4_bit(e1i) << 7);
+ } else {
+ switch (e1i->tx.frame_nr) {
+ case 1:
+ case 3:
+ case 7:
+ ret = 0x40;
+ break;
+ case 5:
+ case 9:
+ case 11:
+ ret = 0xC0;
+ break;
+ case 13:
+ case 15:
+ ret = 0x40;
+ if (e1i->tx.crc4_error)
+ ret |= 0x80;
+ break;
+ }
+ ret |= e1i->tx.sa4_sa8;
+ if (e1i->tx.remote_alarm)
+ ret |= 0x20;
+ }
+
+ /* re-set CRC4 at start of sub-multiframe */
+ if (e1i->tx.frame_nr == 0 || e1i->tx.frame_nr == 8) {
+ e1i->tx.crc4_last_smf = e1i->tx.crc4;
+ e1i->tx.crc4 = 0;
+ }
+
+ /* increment frame number modulo 16 */
+ e1i->tx.frame_nr = (e1i->tx.frame_nr + 1) % 16;
+
+ return ret;
+}
+
+/* pull a single to-be-transmitted byte for TS1..31 */
+static uint8_t e1_pull_tsN(struct osmo_e1f_instance_ts *e1t)
+{
+ struct msgb *msg = llist_first_entry_or_null(&e1t->tx.queue, struct msgb, list);
+ uint8_t *cur;
+
+retry:
+ /* if there's no message to transmit */
+ if (!msg) {
+ e1t->tx.underruns++;
+ return 0xFF;
+ }
+ if (msgb_length(msg) <= 0) {
+ llist_del(&msg->list);
+ msgb_free(msg);
+ msg = llist_first_entry_or_null(&e1t->tx.queue, struct msgb, list);
+ goto retry;
+ }
+ cur = msgb_pull(msg, 1);
+ return *cur;
+}
+
+/* update the current in-progress CRC4 value with data from \a out_frame */
+static void e1_tx_update_crc4(struct osmo_e1f_instance *e1i, const uint8_t *out_frame)
+{
+ uint8_t ts0;
+
+ ts0 = out_frame[0];
+ /* mask off the C bits */
+ if (is_correct_fas(ts0))
+ ts0 &= 0x7F;
+ e1i->tx.crc4 = crc4itu_update(e1i->tx.crc4, &ts0, 1);
+ /* add the remaining bytes/bits */
+ e1i->tx.crc4 = crc4itu_update(e1i->tx.crc4, out_frame+1, ARRAY_SIZE(e1i->ts)-1);
+}
+
+/*! Pull one to-be-transmitted E1 frame (256bits) from the E1 instance
+ * \param e1i E1 instance for which the frame shall be generated
+ * \param[out] out_frame callee-allocated buffer to which function stores 32 bytes
+ * \returns 0 on success, negative on error */
+int osmo_e1f_pull_tx_frame(struct osmo_e1f_instance *e1i, uint8_t *out_frame)
+{
+ int i;
+
+ /* generate TS0 */
+ out_frame[0] = e1_pull_ts0(e1i);
+
+ /* generate TS1..31 */
+ for (i = 1; i < ARRAY_SIZE(e1i->ts); i++) {
+ struct osmo_e1f_instance_ts *e1t = &e1i->ts[i];
+ /* get next to-be-transmitted byte from the TS */
+ out_frame[i] = e1_pull_tsN(e1t);
+ }
+ /* update our CRC4 computation */
+ e1_tx_update_crc4(e1i, out_frame);
+
+ return 0;
+}
+
+/***********************************************************************
+ * Receiver Side
+ ***********************************************************************/
+
+/* According to Figure 2 / ITU-T G.706 */
+enum e1_align_state {
+ /* Frame Alignment Search */
+ E1_AS_SEARCH_FRAME,
+ /* CRC multiframe alignment search */
+ E1_AS_SEARCH_CRC_MFRAME,
+ /* monitoring for incorrect frame alignment and error performance using CRC */
+ E1_AS_ALIGNED_CRC_MFRAME,
+ /* no CRC: just frame alignment loss check */
+ E1_AS_ALIGNED_BASIC,
+};
+
+enum e1_align_event {
+ /* received a TS0 octet */
+ E1_AE_RX_TS0,
+ E1_AE_RESET
+};
+
+static const struct value_string e1_align_evt_names[] = {
+ { E1_AE_RX_TS0, "E1_AE_RX_TS0" },
+ { E1_AE_RESET, "E1_AE_RESET" },
+ { 0, NULL }
+};
+
+/* get a TS0 byte from the history. delta 0 == current, delte 1 == previous, ... */
+static uint8_t get_ts0_hist(struct osmo_e1f_instance *e1i, uint8_t delta)
+{
+ return e1i->rx.ts0_history[((e1i->rx.frame_nr + 16)-delta) % 16];
+}
+
+/* ITU-T G.706 Section 4.1.1 */
+static bool frame_alignment_lost(struct osmo_e1f_instance *e1i)
+{
+ if (e1i->rx.frame_nr % 2)
+ return false;
+
+ /* Frame alignment will be assumed to have been lost when three consecutive incorrect
+ * frame alignment signals have been received. */
+ if (!is_correct_fas(get_ts0_hist(e1i, 0)) &&
+ !is_correct_fas(get_ts0_hist(e1i, 2)) &&
+ !is_correct_fas(get_ts0_hist(e1i, 4)))
+ return true;
+ else
+ return false;
+}
+
+/* ITU-T G.706 Section 4.1.2 */
+static bool frame_alignment_recovered(struct osmo_e1f_instance *e1i)
+{
+ /* two consecutive FAS with one non-FAS interspersed */
+ if (is_correct_fas(get_ts0_hist(e1i, 0)) &&
+ !is_correct_fas(get_ts0_hist(e1i, 1)) &&
+ is_correct_fas(get_ts0_hist(e1i, 2)))
+ return true;
+ else
+ return false;
+}
+
+/* ITU-T G.706 Section 4.2 */
+static bool crc_mframe_alignment_achieved(struct osmo_e1f_instance *e1i)
+{
+ /* if current TS0 byte is FAS, we cannot detect alignment */
+ if (is_correct_fas(get_ts0_hist(e1i, 0)))
+ return false;
+ if ((get_ts0_hist(e1i, 0) >> 7) == 1 &&
+ (get_ts0_hist(e1i, 2) >> 7) == 1 &&
+ (get_ts0_hist(e1i, 4) >> 7) == 0 &&
+ (get_ts0_hist(e1i, 6) >> 7) == 1 &&
+ (get_ts0_hist(e1i, 8) >> 7) == 0 &&
+ (get_ts0_hist(e1i, 10) >> 7) == 0)
+ return true;
+ else
+ return false;
+}
+
+/* Get the CRC4 that was received from our Rx TS0 history */
+static uint8_t crc4_from_ts0_hist(struct osmo_e1f_instance *e1i, bool smf2)
+{
+ uint8_t crc = 0;
+ uint8_t offset = 0;
+
+ if (smf2)
+ offset = 8;
+
+ crc |= (e1i->rx.ts0_history[0+offset] >> 7) << 3;
+ crc |= (e1i->rx.ts0_history[2+offset] >> 7) << 2;
+ crc |= (e1i->rx.ts0_history[4+offset] >> 7) << 1;
+ crc |= (e1i->rx.ts0_history[6+offset] >> 7) << 0;
+
+ return crc;
+}
+
+/* update the current in-progress CRC4 value with data from \a rx_frame */
+static void e1_rx_update_crc4(struct osmo_e1f_instance *e1i, const uint8_t *rx_frame)
+{
+ uint8_t ts0;
+
+ ts0 = rx_frame[0];
+ /* mask off the C bits */
+ if (is_correct_fas(ts0))
+ ts0 &= 0x7F;
+ e1i->rx.crc4 = crc4itu_update(e1i->rx.crc4, &ts0, 1);
+ /* add the remaining bytes/bits */
+ e1i->rx.crc4 = crc4itu_update(e1i->rx.crc4, rx_frame+1, ARRAY_SIZE(e1i->ts)-1);
+}
+
+/* FSM State handler */
+static void e1_align_search_frame(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+ struct osmo_e1f_instance *e1i = (struct osmo_e1f_instance *) fi->priv;
+
+ if (frame_alignment_recovered(e1i)) {
+ /* if we detected the 2nd FAS, we must be in FN 2 (or at least FN%2=0 */
+ e1i->rx.frame_nr = 2;
+ notify_user(e1i, E1_NTFY_EVT_ALIGN_FRAME, true, NULL);
+ osmo_fsm_inst_state_chg(fi, E1_AS_SEARCH_CRC_MFRAME, 0, 0);
+ }
+}
+
+/* FSM State handler */
+static void e1_align_search_crc_mframe(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+ struct osmo_e1f_instance *e1i = (struct osmo_e1f_instance *) fi->priv;
+
+ if (crc_mframe_alignment_achieved(e1i)) {
+ /* if we detected the 6-bit CRC multiframe signal, we must be in FN 11 */
+ e1i->rx.frame_nr = 11;
+ /* FIXME: "at least two valid CRC multiframe alignment signals can be located within
+ * 8 ms, the time separating two CRC multiframe alignment signals being 2 ms or a
+ * multiple of 2 ms" */
+ notify_user(e1i, E1_NTFY_EVT_ALIGN_CRC_MFRAME, true, NULL);
+ osmo_fsm_inst_state_chg(fi, E1_AS_ALIGNED_CRC_MFRAME, 0, 0);
+ } else {
+ /* if no mframe alignment is established within 8ms (64 frames), fall back */
+ if (e1i->rx.num_ts0_in_mframe_search >= 64) {
+ e1i->rx.num_ts0_in_mframe_search = 0;
+ osmo_fsm_inst_state_chg(fi, E1_AS_SEARCH_FRAME, 0, 0);
+ }
+ e1i->rx.num_ts0_in_mframe_search++;
+ }
+}
+
+static void e1_aligned_common(struct osmo_e1f_instance *e1i)
+{
+ uint8_t inb = get_ts0_hist(e1i, 0);
+
+ /* All non-FAS frames contain "A" bit in TS0 */
+ if (!is_correct_fas(inb & 0x7F)) {
+ bool old_alarm = e1i->rx.remote_alarm;
+ /* frame not containing the frame alignment signal */
+ if (inb & 0x20)
+ e1i->rx.remote_alarm = true;
+ else
+ e1i->rx.remote_alarm = false;
+ if (old_alarm != e1i->rx.remote_alarm)
+ notify_user(e1i, E1_NTFY_EVT_REMOTE_ALARM, e1i->rx.remote_alarm, NULL);
+ }
+}
+
+/* FSM State handler */
+static void e1_aligned_crc_mframe(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+ struct osmo_e1f_instance *e1i = (struct osmo_e1f_instance *) fi->priv;
+
+ if (frame_alignment_lost(e1i)) {
+ osmo_fsm_inst_state_chg(fi, E1_AS_SEARCH_FRAME, 0, 0);
+ return;
+ }
+
+ if (e1i->crc4_enabled) {
+ uint8_t crc_rx;
+ bool crc4_error;
+
+ /* check if we just received a complete CRC4 */
+ switch (e1i->rx.frame_nr) {
+ case 7:
+ case 15:
+ crc_rx = crc4_from_ts0_hist(e1i, e1i->rx.frame_nr == 15 ? true : false);
+ if (crc_rx != e1i->rx.crc4_last_smf)
+ crc4_error = true;
+ else
+ crc4_error = false;
+ if (crc4_error != e1i->tx.crc4_error) {
+ notify_user(e1i, E1_NTFY_EVT_CRC_ERROR, crc4_error, NULL);
+ e1i->tx.crc4_error = crc4_error;
+ }
+ /* rotate computed CRC4 one further */
+ e1i->rx.crc4_last_smf = e1i->rx.crc4;
+ e1i->rx.crc4 = crc4itu_init();
+ break;
+ default:
+ break;
+ }
+
+ /* check if the remote side reports any CRC errors */
+ switch (e1i->rx.frame_nr) {
+ case 13:
+ case 15:
+ crc4_error = false;
+ if ((get_ts0_hist(e1i, 0) >> 7) == 0)
+ crc4_error = true;
+ if (crc4_error != e1i->rx.remote_crc4_error) {
+ notify_user(e1i, E1_NTFY_EVT_REMOTE_CRC_ERROR, crc4_error, NULL);
+ e1i->rx.remote_crc4_error = crc4_error;
+ }
+ break;
+ }
+ }
+
+ e1_aligned_common(e1i);
+}
+
+/* FSM State handler */
+static void e1_aligned_basic(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+ struct osmo_e1f_instance *e1i = (struct osmo_e1f_instance *) fi->priv;
+
+ if (frame_alignment_lost(e1i)) {
+ osmo_fsm_inst_state_chg(fi, E1_AS_SEARCH_FRAME, 0, 0);
+ return;
+ }
+
+ e1_aligned_common(e1i);
+}
+
+static const struct osmo_fsm_state e1_align_states[] = {
+ [E1_AS_SEARCH_FRAME] = {
+ .name = "SEARCH_FRAME",
+ .in_event_mask = S(E1_AE_RX_TS0),
+ .out_state_mask = S(E1_AS_SEARCH_FRAME) |
+ S(E1_AS_SEARCH_CRC_MFRAME) |
+ S(E1_AS_ALIGNED_BASIC),
+ .action = e1_align_search_frame,
+ },
+ [E1_AS_SEARCH_CRC_MFRAME] = {
+ .name = "SEARCH_CRC_MFRAME",
+ .in_event_mask = S(E1_AE_RX_TS0),
+ .out_state_mask = S(E1_AS_SEARCH_FRAME) |
+ S(E1_AS_SEARCH_CRC_MFRAME) |
+ S(E1_AS_ALIGNED_CRC_MFRAME),
+ .action = e1_align_search_crc_mframe,
+ },
+ [E1_AS_ALIGNED_CRC_MFRAME] = {
+ .name = "ALIGNED_CRC_MFRAME",
+ .in_event_mask = S(E1_AE_RX_TS0),
+ .out_state_mask = S(E1_AS_SEARCH_FRAME) |
+ S(E1_AS_SEARCH_CRC_MFRAME) |
+ S(E1_AS_ALIGNED_CRC_MFRAME),
+ .action = e1_aligned_crc_mframe,
+ },
+ [E1_AS_ALIGNED_BASIC] = {
+ .name = "ALIGNED_BASIC",
+ .in_event_mask = S(E1_AE_RX_TS0),
+ .out_state_mask = S(E1_AS_SEARCH_FRAME),
+ .action = e1_aligned_basic,
+ },
+};
+
+static void e1_allstate(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+ struct osmo_e1f_instance *e1i = (struct osmo_e1f_instance *) fi->priv;
+
+ switch (event) {
+ case E1_AE_RESET:
+ e1i->rx.num_ts0_in_mframe_search = 0;
+ osmo_fsm_inst_state_chg(fi, E1_AS_SEARCH_FRAME, 0, 0);
+ break;
+ }
+}
+
+static struct osmo_fsm e1_align_fsm = {
+ .name = "e1-align",
+ .states = e1_align_states,
+ .num_states = ARRAY_SIZE(e1_align_states),
+ .allstate_event_mask = S(E1_AE_RESET),
+ .allstate_action = e1_allstate,
+ .log_subsys = DLGLOBAL,
+ .event_names = e1_align_evt_names,
+};
+
+static void align_fsm_reset(struct osmo_e1f_instance *e1i)
+{
+ osmo_fsm_inst_dispatch(e1i->rx.fi, E1_AE_RESET, NULL);
+}
+
+static void e1_rx_hist_add(struct osmo_e1f_instance *e1i, uint8_t inb)
+{
+ e1i->rx.ts0_history[e1i->rx.frame_nr] = inb;
+ if (e1i->rx.ts0_hist_len < 16)
+ e1i->rx.ts0_hist_len++;
+}
+
+static void e1_rx_ts0(struct osmo_e1f_instance *e1i, uint8_t inb)
+{
+ /* append just-received byte to the TS0 receive history buffer */
+ e1_rx_hist_add(e1i, inb);
+
+ /* notify the FSM that a new TS0 byte was received */
+ osmo_fsm_inst_dispatch(e1i->rx.fi, E1_AE_RX_TS0, NULL);
+
+ e1i->rx.frame_nr = (e1i->rx.frame_nr + 1) % 16;
+}
+
+static void e1_rx_tsN(struct osmo_e1f_instance_ts *e1t, uint8_t inb)
+{
+ struct msgb *msg;
+ int count, rc;
+
+ if (!e1t->rx.enabled)
+ return;
+
+ if (!e1t->rx.msg)
+ e1t->rx.msg = msgb_alloc(e1t->rx.granularity, "E1 Rx");
+ msg = e1t->rx.msg;
+ OSMO_ASSERT(msg);
+
+ switch (e1t->mode) {
+ case OSMO_E1F_TS_RAW:
+ /* append byte at end of msgb */
+ msgb_put_u8(msg, inb);
+ /* flush msgb, if full */
+ if (msgb_tailroom(msg) <= 0) {
+ goto flush;
+ }
+ break;
+ case OSMO_E1F_TS_HDLC_CRC:
+ rc = osmo_isdnhdlc_decode(&e1t->rx.hdlc, &inb, 1, &count,
+ msgb_data(msg), msgb_tailroom(msg));
+ switch (rc) {
+ case -OSMO_HDLC_FRAMING_ERROR:
+ fprintf(stdout, "Framing Error\n");
+ break;
+ case -OSMO_HDLC_CRC_ERROR:
+ fprintf(stdout, "CRC Error\n");
+ break;
+ case -OSMO_HDLC_LENGTH_ERROR:
+ fprintf(stdout, "Length Error\n");
+ break;
+ case 0:
+ /* no output yet */
+ break;
+ default:
+ msgb_put(msg, rc);
+ goto flush;
+ }
+ break;
+ }
+
+ return;
+flush:
+
+ if (!e1t->rx.data_cb)
+ msgb_free(msg);
+ else
+ e1t->rx.data_cb(e1t, msg);
+ e1t->rx.msg = NULL;
+}
+
+/*! Receive a single E1 frame of 32x8 (=256) bits
+ * \param e1i E1 instance for which the frame was received
+ * \param[in] in_frame caller-provided buffer of 32 octets
+ *
+ * The idea is that whoever calls us will already have done the bit-alignment,
+ * i.e. the first bit of TS0 of the frame will be octet-aligned and hence the
+ * entire 256bit buffer is provided as octet-aligned 32bytes in \a in_frame.
+ */
+int osmo_e1f_rx_frame(struct osmo_e1f_instance *e1i, const uint8_t *in_frame)
+{
+ int i;
+
+ e1_rx_update_crc4(e1i, in_frame);
+
+ e1_rx_ts0(e1i, in_frame[0]);
+
+ for (i = 1; i < ARRAY_SIZE(e1i->ts); i++) {
+ struct osmo_e1f_instance_ts *e1t = &e1i->ts[i];
+ e1_rx_tsN(e1t, in_frame[i]);
+ }
+
+ return 0;
+}
+
+int osmo_e1f_init(void)
+{
+ return osmo_fsm_register(&e1_align_fsm);
+}