Add new "osmo-e1gen" program.laforge/e1gen

osmo-e1gen is a program that re-uses large parts of osmo-e1d, but whose
main purpose is to generate a variety of error conditions in order to
test a remote E1 implementation.

Instead of using the automatisms of the icE1usb transmit IP core, it
switches it to transparent mode and uses a host-software based E1 framer
"osmo_e1f", over which we have more control than the firmware.

Change-Id: I53a86d6730eb76a9cff9eb3f4786139015c91230

7 files changed, 1427 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index fd61f5a..cf18d60 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -32,6 +32,10 @@ bin_PROGRAMS = \
 	osmo-e1d-pipe \
 	$(NULL)
 
+noinst_PROGRAMS = \
+	osmo-e1gen \
+	$(NULL)
+
 osmo_e1d_SOURCES = \
 	ctl.c \
 	intf_line.c \
@@ -51,3 +55,17 @@ osmo_e1d_pipe_SOURCES = \
 	$(NULL)
 
 osmo_e1d_pipe_LDADD = $(LIBOSMOCORE_LIBS) libosmo-e1d.la
+
+
+osmo_e1gen_LDADD = $(LIBOSMOCORE_LIBS) $(LIBOSMOVTY_LIBS) \
+		   $(LIBOSMOUSB_LIBS) $(LIBUSB_LIBS)
+
+osmo_e1gen_SOURCES = \
+	intf_line.c \
+	log.c \
+	e1gen/crc4itu.c \
+	e1gen/osmo_e1f.c \
+	osmo-e1gen.c \
+	usb.c \
+	vty.c \
+	$(NULL)
diff --git a/src/e1d.h b/src/e1d.h
index b4bb754..eca780a 100644
--- a/src/e1d.h
+++ b/src/e1d.h
@@ -101,6 +101,8 @@ struct e1_line {
 	struct e1_ts ts[32];
 	/* superchannel */
 	struct e1_ts superchan;
+
+	void *e1gen_priv;
 };
 
 enum e1_driver {
diff --git a/src/e1gen/crc4itu.c b/src/e1gen/crc4itu.c
new file mode 100644
index 0000000..f13895a
--- /dev/null
+++ b/src/e1gen/crc4itu.c
@@ -0,0 +1,56 @@
+/**
+ * \file
+ * Functions and types for CRC checks.
+ *
+ * Generated on Sat May 12 09:39:22 2018
+ * by pycrc v0.9.1, https://pycrc.org
+ * using the configuration:
+ *  - Width         = 4
+ *  - Poly          = 0x3
+ *  - XorIn         = 0x0
+ *  - ReflectIn     = False
+ *  - XorOut        = 0x0
+ *  - ReflectOut    = False
+ *  - Algorithm     = table-driven
+ */
+#include "crc4itu.h"     /* include the header file generated with pycrc */
+#include <stdlib.h>
+#include <stdint.h>
+
+
+
+/**
+ * Static table used for the table_driven implementation.
+ */
+static const crc_t crc_table[256] = {
+    0x00, 0x03, 0x06, 0x05, 0x0c, 0x0f, 0x0a, 0x09, 0x0b, 0x08, 0x0d, 0x0e, 0x07, 0x04, 0x01, 0x02,
+    0x05, 0x06, 0x03, 0x00, 0x09, 0x0a, 0x0f, 0x0c, 0x0e, 0x0d, 0x08, 0x0b, 0x02, 0x01, 0x04, 0x07,
+    0x0a, 0x09, 0x0c, 0x0f, 0x06, 0x05, 0x00, 0x03, 0x01, 0x02, 0x07, 0x04, 0x0d, 0x0e, 0x0b, 0x08,
+    0x0f, 0x0c, 0x09, 0x0a, 0x03, 0x00, 0x05, 0x06, 0x04, 0x07, 0x02, 0x01, 0x08, 0x0b, 0x0e, 0x0d,
+    0x07, 0x04, 0x01, 0x02, 0x0b, 0x08, 0x0d, 0x0e, 0x0c, 0x0f, 0x0a, 0x09, 0x00, 0x03, 0x06, 0x05,
+    0x02, 0x01, 0x04, 0x07, 0x0e, 0x0d, 0x08, 0x0b, 0x09, 0x0a, 0x0f, 0x0c, 0x05, 0x06, 0x03, 0x00,
+    0x0d, 0x0e, 0x0b, 0x08, 0x01, 0x02, 0x07, 0x04, 0x06, 0x05, 0x00, 0x03, 0x0a, 0x09, 0x0c, 0x0f,
+    0x08, 0x0b, 0x0e, 0x0d, 0x04, 0x07, 0x02, 0x01, 0x03, 0x00, 0x05, 0x06, 0x0f, 0x0c, 0x09, 0x0a,
+    0x0e, 0x0d, 0x08, 0x0b, 0x02, 0x01, 0x04, 0x07, 0x05, 0x06, 0x03, 0x00, 0x09, 0x0a, 0x0f, 0x0c,
+    0x0b, 0x08, 0x0d, 0x0e, 0x07, 0x04, 0x01, 0x02, 0x00, 0x03, 0x06, 0x05, 0x0c, 0x0f, 0x0a, 0x09,
+    0x04, 0x07, 0x02, 0x01, 0x08, 0x0b, 0x0e, 0x0d, 0x0f, 0x0c, 0x09, 0x0a, 0x03, 0x00, 0x05, 0x06,
+    0x01, 0x02, 0x07, 0x04, 0x0d, 0x0e, 0x0b, 0x08, 0x0a, 0x09, 0x0c, 0x0f, 0x06, 0x05, 0x00, 0x03,
+    0x09, 0x0a, 0x0f, 0x0c, 0x05, 0x06, 0x03, 0x00, 0x02, 0x01, 0x04, 0x07, 0x0e, 0x0d, 0x08, 0x0b,
+    0x0c, 0x0f, 0x0a, 0x09, 0x00, 0x03, 0x06, 0x05, 0x07, 0x04, 0x01, 0x02, 0x0b, 0x08, 0x0d, 0x0e,
+    0x03, 0x00, 0x05, 0x06, 0x0f, 0x0c, 0x09, 0x0a, 0x08, 0x0b, 0x0e, 0x0d, 0x04, 0x07, 0x02, 0x01,
+    0x06, 0x05, 0x00, 0x03, 0x0a, 0x09, 0x0c, 0x0f, 0x0d, 0x0e, 0x0b, 0x08, 0x01, 0x02, 0x07, 0x04
+};
+
+
+crc_t crc4itu_update(crc_t crc, const void *data, size_t data_len)
+{
+    const unsigned char *d = (const unsigned char *)data;
+    unsigned int tbl_idx;
+
+    while (data_len--) {
+        tbl_idx = (crc << 4) ^ *d;
+        crc = crc_table[tbl_idx] & 0xf;
+        d++;
+    }
+    return crc & 0xf;
+}
diff --git a/src/e1gen/crc4itu.h b/src/e1gen/crc4itu.h
new file mode 100644
index 0000000..220b50f
--- /dev/null
+++ b/src/e1gen/crc4itu.h
@@ -0,0 +1,106 @@
+/**
+ * \file
+ * Functions and types for CRC checks.
+ *
+ * Generated on Sat May 12 09:41:12 2018
+ * by pycrc v0.9.1, https://pycrc.org
+ * using the configuration:
+ *  - Width         = 4
+ *  - Poly          = 0x3
+ *  - XorIn         = 0x0
+ *  - ReflectIn     = False
+ *  - XorOut        = 0x0
+ *  - ReflectOut    = False
+ *  - Algorithm     = table-driven
+ *
+ * This file defines the functions crc4itu_init(), crc4itu_update() and crc_finalize().
+ *
+ * The crc4itu_init() function returns the inital \c crc value and must be called
+ * before the first call to crc4itu_update().
+ * Similarly, the crc_finalize() function must be called after the last call
+ * to crc4itu_update(), before the \c crc is being used.
+ * is being used.
+ *
+ * The crc4itu_update() function can be called any number of times (including zero
+ * times) in between the crc4itu_init() and crc_finalize() calls.
+ *
+ * This pseudo-code shows an example usage of the API:
+ * \code{.c}
+ * crc_t crc;
+ * unsigned char data[MAX_DATA_LEN];
+ * size_t data_len;
+ *
+ * crc = crc4itu_init();
+ * while ((data_len = read_data(data, MAX_DATA_LEN)) > 0) {
+ *     crc = crc4itu_update(crc, data, data_len);
+ * }
+ * crc = crc_finalize(crc);
+ * \endcode
+ */
+#ifndef CRC4ITU_H
+#define CRC4ITU_H
+
+#include <stdlib.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/**
+ * The definition of the used algorithm.
+ *
+ * This is not used anywhere in the generated code, but it may be used by the
+ * application code to call algorithm-specific code, if desired.
+ */
+#define CRC_ALGO_TABLE_DRIVEN 1
+
+
+/**
+ * The type of the CRC values.
+ *
+ * This type must be big enough to contain at least 4 bits.
+ */
+typedef uint_fast8_t crc_t;
+
+
+/**
+ * Calculate the initial crc value.
+ *
+ * \return     The initial crc value.
+ */
+static inline crc_t crc4itu_init(void)
+{
+    return 0x0;
+}
+
+
+/**
+ * Update the crc value with new data.
+ *
+ * \param[in] crc      The current crc value.
+ * \param[in] data     Pointer to a buffer of \a data_len bytes.
+ * \param[in] data_len Number of bytes in the \a data buffer.
+ * \return             The updated crc value.
+ */
+crc_t crc4itu_update(crc_t crc, const void *data, size_t data_len);
+
+
+/**
+ * Calculate the final crc value.
+ *
+ * \param[in] crc  The current crc value.
+ * \return     The final crc value.
+ */
+static inline crc_t crc_finalize(crc_t crc)
+{
+    return crc;
+}
+
+
+#ifdef __cplusplus
+}           /* closing brace for extern "C" */
+#endif
+
+#endif      /* CRC4ITU_H */
diff --git a/src/e1gen/osmo_e1f.c b/src/e1gen/osmo_e1f.c
new file mode 100644
index 0000000..2c3fcfb
--- /dev/null
+++ b/src/e1gen/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 = 0x1f;
+
+	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 = 0;
+
+	/* 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;
+	}
+
+	/* 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;
+	}
+
+	/* 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);
+}
diff --git a/src/e1gen/osmo_e1f.h b/src/e1gen/osmo_e1f.h
new file mode 100644
index 0000000..c9d4778
--- /dev/null
+++ b/src/e1gen/osmo_e1f.h
@@ -0,0 +1,122 @@
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/fsm.h>
+#include <osmocom/core/isdnhdlc.h>
+
+struct osmo_e1f_tx_state {
+	bool remote_alarm;
+	bool crc4_error;
+	/* lower 5 bits: Sa4..Sa8 */
+	uint8_t sa4_sa8;
+	/* frame number 0..15 */
+	uint8_t frame_nr;
+	uint8_t crc4_last_smf;
+	uint8_t crc4;
+};
+
+struct osmo_e1f_rx_state {
+	uint8_t frame_nr;
+	/* history of rceived TS0 octets */
+	uint8_t ts0_history[16];
+	uint8_t ts0_hist_len;
+	/* was a remote alarm received? */
+	bool remote_alarm;
+	bool remote_crc4_error;
+	/* number of TS0 bytes received since entering CRC mframe search */
+	uint8_t num_ts0_in_mframe_search;
+	struct osmo_fsm_inst *fi;
+	/* computed CRC4 */
+	uint8_t crc4_last_smf;
+	uint8_t crc4;
+};
+
+enum osmo_e1f_notify_event {
+	E1_NTFY_EVT_ALIGN_FRAME,
+	E1_NTFY_EVT_ALIGN_CRC_MFRAME,
+	E1_NTFY_EVT_CRC_ERROR,
+	E1_NTFY_EVT_REMOTE_CRC_ERROR,
+	E1_NTFY_EVT_REMOTE_ALARM,
+};
+
+enum osmo_e1f_ts_mode {
+       OSMO_E1F_TS_RAW,
+       OSMO_E1F_TS_HDLC_CRC,
+};
+
+struct osmo_e1f_instance_ts;
+struct osmo_e1f_instance;
+typedef void (*e1_data_cb)(struct osmo_e1f_instance_ts *ts, struct msgb *msg);
+typedef void (*e1_notify_cb)(struct osmo_e1f_instance *e1i, enum osmo_e1f_notify_event evt,
+			     bool present, void *data);
+
+struct osmo_e1f_instance_ts {
+	/* timeslot number */
+	uint8_t ts_nr;
+	/* mode in which we operate (RAW/HDLC) */
+	enum osmo_e1f_ts_mode mode;
+	/* back-pointer to e1 instance */
+	struct osmo_e1f_instance *inst;
+	struct {
+		/* optional HDLC encoder state */
+		struct osmo_isdnhdlc_vars hdlc;
+		/* queue of pending to-be-transmitted messages */
+		struct llist_head queue;
+		unsigned long underruns;
+	} tx;
+	struct {
+		/* optional HDLC decoder state */
+		struct osmo_isdnhdlc_vars hdlc;
+		bool enabled;
+		/* how many bytes to buffer before calling call-back */
+		unsigned int granularity;
+		/* current receive buffer */
+		struct msgb *msg;
+		e1_data_cb data_cb;
+		/* private data, relevant to user */
+		void *priv;
+	} rx;
+};
+
+struct osmo_e1f_instance {
+	/* list; currently not used yet */
+	struct llist_head list;
+
+	/* is CRC4 generation + parsing enabled? */
+	bool crc4_enabled;
+	/* notification call-back function */
+	e1_notify_cb notify_cb;
+
+	/* Rx + Tx related state */
+	struct osmo_e1f_tx_state tx;
+	struct osmo_e1f_rx_state rx;
+
+	/* our 32 timeslots (only 1..32 are used) */
+	struct osmo_e1f_instance_ts ts[32];
+
+	/* private data, relevant to user */
+	void *priv;
+};
+
+extern const struct value_string osmo_e1f_notifv_evt_names[];
+
+static inline const char *osmo_e1f_notify_event_name(enum osmo_e1f_notify_event evt) {
+	return get_value_string(osmo_e1f_notifv_evt_names, evt);
+}
+
+int osmo_e1f_init(void);
+struct osmo_e1f_instance_ts *osmo_e1f_instance_ts(struct osmo_e1f_instance *e1i, uint8_t ts_nr);
+int osmo_e1f_instance_init(struct osmo_e1f_instance *e1i, const char *name, e1_notify_cb cb,
+			  bool crc4_enabled, void *priv);
+void osmo_e1f_instance_reset(struct osmo_e1f_instance *e1i);
+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);
+void osmo_e1f_ts_reset(struct osmo_e1f_instance_ts *e1t);
+
+
+void osmo_e1f_ts_enqueue(struct osmo_e1f_instance_ts *e1t, struct msgb *msg);
+int osmo_e1f_pull_tx_frame(struct osmo_e1f_instance *e1i, uint8_t *out_frame);
+int osmo_e1f_rx_frame(struct osmo_e1f_instance *e1i, const uint8_t *in_frame);
diff --git a/src/osmo-e1gen.c b/src/osmo-e1gen.c
new file mode 100644
index 0000000..91e2ff9
--- /dev/null
+++ b/src/osmo-e1gen.c
@@ -0,0 +1,424 @@
+/*
+ * osmo-e1gen.c
+ *
+ * (C) 2020 by Harald Welte <laforge@gnumonks.org>
+ *
+ * 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, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <errno.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+
+#define _GNU_SOURCE
+#include <getopt.h>
+
+#include <talloc.h>
+
+#include <osmocom/core/application.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/select.h>
+#include <osmocom/vty/telnet_interface.h>
+#include <osmocom/vty/logging.h>
+#include <osmocom/vty/vty.h>
+#include <osmocom/vty/command.h>
+
+#include "e1d.h"
+#include "usb.h"
+#include "log.h"
+
+#include "e1gen/osmo_e1f.h"
+
+#ifndef OSMO_VTY_PORT_E1D
+#define OSMO_VTY_PORT_E1D	4269
+#endif
+
+/***********************************************************************
+ * global variables
+ ***********************************************************************/
+
+extern struct e1_daemon *vty_e1d;
+static const char *g_config_file = "osmo-e1d.cfg";
+static void *g_e1d_ctx = NULL;
+static int g_shutdown = 0;
+
+/***********************************************************************
+ * stubs for external linkage of normal osmo-e1d
+ ***********************************************************************/
+
+void e1_ts_stop(struct e1_ts *ts) {}
+int e1d_vpair_create(struct e1_daemon *e1d, unsigned int num_lines) { return -1; }
+struct e1_intf *e1d_vpair_intf_peer(struct e1_intf *intf) { return NULL; }
+
+
+
+struct e1gen_line_data {
+	struct ice1usb_tx_config tx_config;
+	struct ice1usb_rx_config rx_config;
+	struct osmo_e1f_instance e1f;
+};
+
+static void e1f_notify_cb(struct osmo_e1f_instance *e1f, enum osmo_e1f_notify_event evt,
+			  bool present, void *data)
+{
+	struct e1_line *line = e1f->priv;
+	LOGPLI(line, DE1D, LOGL_NOTICE, "NOTIFY: %s %s\n",
+		osmo_e1f_notify_event_name(evt), present ? "PRESENT" : "ABSENT");
+}
+
+static const struct e1gen_line_data default_ld = {
+	.tx_config = {
+		.mode = ICE1USB_TX_MODE_TRANSP,
+		.timing = ICE1USB_TX_TIME_SRC_LOCAL,
+		.ext_loopback = ICE1USB_TX_EXT_LOOPBACK_OFF,
+		.alarm = 0,
+	},
+	.rx_config = {
+		.mode = ICE1USB_RX_MODE_MULTIFRAME,
+		//.mode = ICE1USB_RX_MODE_TRANSP,
+	},
+};
+
+struct e1gen_line_data *ensure_gld(struct e1_line *line)
+{
+	struct e1gen_line_data *gld = (struct e1gen_line_data *) line->e1gen_priv;
+
+	if (gld)
+		return gld;
+
+	LOGPLI(line, DE1D, LOGL_INFO, "Creating e1gen structures\n");
+
+	line->e1gen_priv = gld = talloc_zero(line, struct e1gen_line_data);
+	gld->tx_config = default_ld.tx_config;
+	gld->rx_config = default_ld.rx_config;
+	osmo_e1f_instance_init(&gld->e1f, "LINE", e1f_notify_cb, true, line);
+
+	/* set the default configuration */
+	e1_usb_ctrl_set_tx_cfg(line, gld->tx_config.mode, gld->tx_config.timing,
+				gld->tx_config.ext_loopback, gld->tx_config.alarm);
+	e1_usb_ctrl_set_rx_cfg(line, gld->rx_config.mode);
+
+	return gld;
+}
+
+/*! process (demultiplex) input data for the specified e1_line.
+ *  \param[in] line E1 line for which to genrate output data
+ *  \param[in] buf input buffer of multiplexed data received on line
+ *  \param[in] size size of buf in octets */
+int e1_line_demux_in(struct e1_line *line, const uint8_t *buf, int size)
+{
+	struct e1gen_line_data *gld = ensure_gld(line);
+	int offs;
+
+	for (offs = 0; offs + 32 <= size; offs += 32) {
+		//printf("Rx "OSMO_BIT_SPEC"\n", OSMO_BIT_PRINT(buf[offs]));
+		//printf("Rx %s\n", osmo_hexdump(buf + offs, 32));
+		osmo_e1f_rx_frame(&gld->e1f, buf + offs);
+	}
+	return 0;
+}
+
+/*! generate (multiplex) output data for the specified e1_line
+ *  \param[in] line E1 line for which to genrate output data
+ *  \param[in] buf caller-allocated output buffer for multiplexed data
+ *  \param[in] fts number of E1 frames (32 bytes each) to generate
+ *  \return number of bytes written to buf */
+int e1_line_mux_out(struct e1_line *line, uint8_t *buf, int fts)
+{
+	struct e1gen_line_data *gld = ensure_gld(line);
+	int f;
+
+	//printf("FRAME:\n");
+	for (f = 0; f < fts; f++) {
+		osmo_e1f_pull_tx_frame(&gld->e1f, buf + f*32);
+		//printf("Tx "OSMO_BIT_SPEC"\n", OSMO_BIT_PRINT(buf[f*32]));
+		//printf("Tx %s\n", osmo_hexdump(buf + f*32, 32));
+	}
+
+	return 32*fts;
+}
+
+static struct cmd_node line_node = {
+	(enum node_type) LINE_NODE,
+	"%s(line)# ",
+	1,
+};
+
+#define TX_STR "Transmitter\n"
+
+DEFUN(line_tx_alarm, line_tx_alarm_cmd,
+	"tx report-alarm (0|1)",
+	TX_STR "Report Alarm (A-Bits)\n" "Off\n" "On\n")
+{
+	struct e1_line *line = vty->index;
+	struct e1gen_line_data *gld = ensure_gld(line);
+	int on = atoi(argv[0]);
+
+	gld->e1f.tx.remote_alarm = on ? true : false;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(line_tx_crc4, line_tx_crc4_cmd,
+	"tx generate-crc4 (0|1)",
+	TX_STR "Generate CRC4\n" "Off\n" "On\n")
+{
+	struct e1_line *line = vty->index;
+	struct e1gen_line_data *gld = ensure_gld(line);
+	int on = atoi(argv[0]);
+
+	gld->e1f.crc4_enabled = on ? true : false;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(line_tx_report_crc4, line_tx_report_crc4_cmd,
+	"tx report-crc4-error (0|1)",
+	TX_STR "Report a CRC4 Error\n" "Off\n" "On\n")
+{
+	struct e1_line *line = vty->index;
+	struct e1gen_line_data *gld = ensure_gld(line);
+	int on = atoi(argv[0]);
+
+	gld->e1f.tx.crc4_error = on ? true : false;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(line_tx_sa48, line_tx_sa48_cmd,
+	"tx sa4 <0-31>",
+	TX_STR "Set the SA4..SA8 bit content\n")
+{
+	struct e1_line *line = vty->index;
+	struct e1gen_line_data *gld = ensure_gld(line);
+
+	gld->e1f.tx.sa4_sa8 = atoi(argv[0]);
+
+	return CMD_SUCCESS;
+}
+
+
+DEFUN(line_show, line_show_cmd,
+	"show", "Show Line status\n")
+{
+	struct e1_line *line = vty->index;
+	struct e1gen_line_data *gld = ensure_gld(line);
+	struct osmo_e1f_instance *e1f = &gld->e1f;
+
+	vty_out(vty, "Rx RemoteAlarm=%u, RemoteCrcErr=%u%s",
+		e1f->rx.remote_alarm, e1f->rx.remote_crc4_error, VTY_NEWLINE);
+	vty_out(vty, "Tx RemoteAlarm=%u, CrcErr=%u%s",
+		e1f->tx.remote_alarm, e1f->tx.crc4_error, VTY_NEWLINE);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(line, line_cmd,
+	"interface <0-255> line <0-225>",
+	"E1 Interface\n" "E1 Interface\n"
+	"E1 Line number\n" "E1 Line number\n")
+{
+	struct e1_intf *intf;
+	struct e1_line *line;
+
+	intf = e1d_find_intf(vty_e1d, atoi(argv[0]));
+	if (!intf) {
+		vty_out(vty, "No such interface %s%s", argv[0], VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	line = e1_intf_find_line(intf, atoi(argv[1]));
+	if (!line) {
+		vty_out(vty, "No such line %s in interface %s%s", argv[1], argv[0], VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	vty->node = LINE_NODE;
+	vty->index = line;
+
+	return CMD_SUCCESS;
+}
+
+static void e1gen_init(void)
+{
+	install_element(ENABLE_NODE, &line_cmd);
+	install_node(&line_node, NULL);
+	install_element(LINE_NODE, &line_tx_alarm_cmd);
+	install_element(LINE_NODE, &line_tx_crc4_cmd);
+	install_element(LINE_NODE, &line_tx_report_crc4_cmd);
+	install_element(LINE_NODE, &line_tx_sa48_cmd);
+	install_element(LINE_NODE, &line_show_cmd);
+}
+
+/***********************************************************************
+ * initialization (mostly shared with osmo-e1d.c
+ ***********************************************************************/
+
+static struct vty_app_info vty_info = {
+	.name = "osmo-e1gen",
+	.version = PACKAGE_VERSION,
+	.copyright =
+	"(C) 2019-2020 by Sylvain Munaut and Harald Welte\r\n",
+	"License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl-2.0.html>\r\n"
+	"This is free software: you are free to change and redistribute it.\r\n"
+	"There is NO WARRANTY, to the extent permitted by law.\r\n",
+};
+
+static void sig_handler(int signo)
+{
+	fprintf(stdout, "signal %d received\n", signo);
+	switch (signo) {
+	case SIGINT:
+	case SIGTERM:
+		fprintf(stdout, "shutting down\n");
+		g_shutdown = 1;
+		break;
+	case SIGABRT:
+	case SIGUSR1:
+		talloc_report(g_e1d_ctx, stderr);
+		talloc_report_full(g_e1d_ctx, stderr);
+		break;
+	case SIGUSR2:
+		talloc_report_full(g_e1d_ctx, stderr);
+		break;
+	default:
+		break;
+	}
+}
+
+static void print_help(void)
+{
+	printf("  Some useful help...\n");
+	printf("  -h --help			This text.\n");
+	printf("  -d --debug option		--debug=DE1D:DXFR enable debugging.\n");
+	printf("  -c --config-file filename	The config file to use.\n");
+}
+
+static void handle_options(int argc, char **argv)
+{
+	while (1) {
+		int option_index = 0, c;
+		static const struct option long_options[] = {
+			{"help", 0, 0, 'h'},
+			{"debug", 1, 0, 'd'},
+			{"config-file", 1, 0, 'c'},
+			{0, 0, 0, 0}
+		};
+
+		c = getopt_long(argc, argv, "hd:c:", long_options, &option_index);
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'h':
+			print_help();
+			exit(0);
+			break;
+		case 'd':
+			log_parse_category_mask(osmo_stderr_target, optarg);
+			break;
+		case 'c':
+			g_config_file = optarg;
+			break;
+		default:
+			fprintf(stderr, "Error in command line options. Exiting.\n");
+			exit(-1);
+		}
+	}
+
+	if (argc > optind) {
+		fprintf(stderr, "Unsupported positional arguments on command line\n");
+		exit(2);
+	}
+}
+
+int main(int argc, char **argv)
+{
+	struct e1_daemon *e1d = NULL;
+	struct sched_param sp;
+	int rv;
+
+	/* talloc init */
+	g_e1d_ctx = talloc_named_const(NULL, 0, "osmo-e1d");
+	msgb_talloc_ctx_init(g_e1d_ctx, 0);
+
+	/* logging init */
+	osmo_init_logging2(g_e1d_ctx, &log_info);
+
+	/* signals init */
+	signal(SIGINT, &sig_handler);
+	signal(SIGTERM, &sig_handler);
+	signal(SIGABRT, &sig_handler);
+	signal(SIGUSR1, &sig_handler);
+	signal(SIGUSR2, &sig_handler);
+	osmo_init_ignore_signals();
+
+	/* rt prio */
+	memset(&sp, 0x00, sizeof(sp));
+        sp.sched_priority = 50;
+        rv = sched_setscheduler(0, SCHED_RR, &sp);
+	if (rv != 0) {
+		LOGP(DE1D, LOGL_ERROR, "Failed to set Real-Time priority. USB comms might be unstable.\n");
+		perror("sched_setscheduler");
+	}
+
+	/* main state */
+	e1d = talloc_zero(g_e1d_ctx, struct e1_daemon);
+	OSMO_ASSERT(e1d);
+
+	INIT_LLIST_HEAD(&e1d->interfaces);
+	vty_init(&vty_info);
+	logging_vty_add_cmds();
+	e1d_vty_init(e1d);
+
+	handle_options(argc, argv);
+
+	rv = vty_read_config_file(g_config_file, NULL);
+	if (rv < 0) {
+		LOGP(DE1D, LOGL_FATAL, "Failed to parse the config file '%s'\n", g_config_file);
+		exit(2);
+	}
+
+	rv = telnet_init_dynif(g_e1d_ctx, e1d, vty_get_bind_addr(), OSMO_VTY_PORT_E1D);
+	if (rv != 0) {
+		LOGP(DE1D, LOGL_FATAL, "Failed to bind VTY interface to %s:%u\n",
+			vty_get_bind_addr(), OSMO_VTY_PORT_E1D);
+		exit(1);
+	}
+
+	osmo_e1f_init();
+	e1gen_init();
+
+	/* probe devices */
+	rv = e1_usb_probe(e1d);
+	if (rv != 0) {
+		LOGP(DE1D, LOGL_ERROR, "Failed to prove usb devices\n");
+	}
+
+	/* main loop */
+	while (!g_shutdown) {
+		osmo_select_main(0);
+	}
+
+	talloc_free(e1d);
+
+	return 0;
+}