pdch/tbf: Move gprs_rlcmac_rcv_data_block_acknowledged into the pdch

Move the method into the PDCH. Extract the finding of TLLI into a
new class called Decoding. Move the assemble and forward LLC frames
into the TBF as it is poking in the internals of the TBF.

10 files changed, 571 insertions, 472 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index d1cbd4b..d2f1fce 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -47,7 +47,8 @@ libgprs_la_SOURCES = \
 	poll_controller.cpp \
 	encoding.cpp \
 	ta.cpp \
-	sba.cpp
+	sba.cpp \
+	decoding.cpp
 
 if ENABLE_SYSMOBTS
 libgprs_la_SOURCES += \
@@ -85,7 +86,9 @@ noinst_HEADERS = \
 	poll_controller.h \
 	encoding.h \
 	ta.h \
-	sba.h
+	sba.h \
+	rlc.h \
+	decoding.h
 
 osmo_pcu_SOURCES = pcu_main.cpp
 
diff --git a/src/bts.cpp b/src/bts.cpp
index af1a819..9567214 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -22,6 +22,8 @@
 #include <poll_controller.h>
 #include <tbf.h>
 #include <encoding.h>
+#include <decoding.h>
+#include <rlc.h>
 
 #include <gprs_rlcmac.h>
 #include <gprs_debug.h>
@@ -212,6 +214,14 @@ gprs_rlcmac_tbf *BTS::tbf_by_poll_fn(uint32_t fn, uint8_t trx, uint8_t ts)
 	return NULL;
 }
 
+
+/*
+ * PDCH code below. TODO: move to a separate file
+ */
+
+/* After receiving these frames, we send ack/nack. */
+#define SEND_ACK_AFTER_FRAMES 20
+
 void gprs_rlcmac_pdch::enable()
 {
 	/* TODO: Check if there are still allocated resources.. */
@@ -340,6 +350,228 @@ void gprs_rlcmac_pdch::add_paging(struct gprs_rlcmac_paging *pag)
 	llist_add(&pag->list, &paging_list);
 }
 
+/* receive UL data block
+ *
+ * The blocks are defragmented and forwarded as LLC frames, if complete.
+ */
+int gprs_rlcmac_pdch::rcv_data_block_acknowledged(struct gprs_rlcmac_bts *bts,
+	uint8_t trx, uint8_t ts,
+	uint8_t *data, uint8_t len, int8_t rssi)
+{
+	struct gprs_rlcmac_tbf *tbf;
+	struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
+	uint16_t mod_sns, mod_sns_half, offset_v_q, offset_v_r, index;
+	int rc;
+
+	switch (len) {
+		case 54:
+			/* omitting spare bits */
+			len = 53;
+			break;
+		case 40:
+			/* omitting spare bits */
+			len = 39;
+			break;
+		case 34:
+			/* omitting spare bits */
+			len = 33;
+			break;
+		case 23:
+			break;
+	default:
+		LOGP(DRLCMACUL, LOGL_ERROR, "Dropping data block with invalid"
+			"length: %d)\n", len);
+		return -EINVAL;
+	}
+
+	/* find TBF inst from given TFI */
+	tbf = tbf_by_tfi(bts, rh->tfi, trx, GPRS_RLCMAC_UL_TBF);
+	if (!tbf) {
+		LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA unknown TBF=%d\n",
+			rh->tfi);
+		return 0;
+	}
+	tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_UL_DATA);
+
+	LOGP(DRLCMACUL, LOGL_DEBUG, "UL DATA TBF=%d received (V(Q)=%d .. "
+		"V(R)=%d)\n", rh->tfi, tbf->dir.ul.v_q, tbf->dir.ul.v_r);
+
+	/* process RSSI */
+	gprs_rlcmac_rssi(tbf, rssi);
+
+	/* get TLLI */
+	if (!tbf->tlli_valid) {
+		struct gprs_rlcmac_tbf *dl_tbf, *ul_tbf;
+
+		/* no TLLI yet */
+		if (!rh->ti) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TBF=%d without "
+				"TLLI, but no TLLI received yet\n", rh->tfi);
+			return 0;
+		}
+		rc = Decoding::tlli_from_ul_data(data, len, &tbf->tlli);
+		if (rc) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "Failed to decode TLLI "
+				"of UL DATA TBF=%d.\n", rh->tfi);
+			return 0;
+		}
+		LOGP(DRLCMACUL, LOGL_INFO, "Decoded premier TLLI=0x%08x of "
+			"UL DATA TBF=%d.\n", tbf->tlli, rh->tfi);
+		if ((dl_tbf = bts->bts->tbf_by_tlli(tbf->tlli, GPRS_RLCMAC_DL_TBF))) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "Got RACH from "
+				"TLLI=0x%08x while DL TBF=%d still exists. "
+				"Killing pending DL TBF\n", tbf->tlli,
+				dl_tbf->tfi);
+			tbf_free(dl_tbf);
+		}
+		/* tbf_by_tlli will not find your TLLI, because it is not
+		 * yet marked valid */
+		if ((ul_tbf = bts->bts->tbf_by_tlli(tbf->tlli, GPRS_RLCMAC_UL_TBF))) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "Got RACH from "
+				"TLLI=0x%08x while UL TBF=%d still exists. "
+				"Killing pending UL TBF\n", tbf->tlli,
+				ul_tbf->tfi);
+			tbf_free(ul_tbf);
+		}
+		/* mark TLLI valid now */
+		tbf->tlli_valid = 1;
+		/* store current timing advance */
+		bts->bts->timing_advance()->remember(tbf->tlli, tbf->ta);
+	/* already have TLLI, but we stille get another one */
+	} else if (rh->ti) {
+		uint32_t tlli;
+		rc = Decoding::tlli_from_ul_data(data, len, &tlli);
+		if (rc) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "Failed to decode TLLI "
+				"of UL DATA TBF=%d.\n", rh->tfi);
+			return 0;
+		}
+		if (tlli != tbf->tlli) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "TLLI mismatch on UL "
+				"DATA TBF=%d. (Ignoring due to contention "
+				"resolution)\n", rh->tfi);
+			return 0;
+		}
+	}
+
+	mod_sns = tbf->sns - 1;
+	mod_sns_half = (tbf->sns >> 1) - 1;
+
+	/* restart T3169 */
+	tbf_timer_start(tbf, 3169, bts->t3169, 0);
+
+	/* Increment RX-counter */
+	tbf->dir.ul.rx_counter++;
+
+	/* current block relative to lowest unreceived block */
+	offset_v_q = (rh->bsn - tbf->dir.ul.v_q) & mod_sns;
+	/* If out of window (may happen if blocks below V(Q) are received
+	 * again. */
+	if (offset_v_q >= tbf->ws) {
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- BSN %d out of window "
+			"%d..%d (it's normal)\n", rh->bsn, tbf->dir.ul.v_q,
+			(tbf->dir.ul.v_q + tbf->ws - 1) & mod_sns);
+		return 0;
+	}
+	/* Write block to buffer and set receive state array. */
+	index = rh->bsn & mod_sns_half; /* memory index of block */
+	memcpy(tbf->rlc_block[index], data, len); /* Copy block. */
+	tbf->rlc_block_len[index] = len;
+	tbf->dir.ul.v_n[index] = 'R'; /* Mark received block. */
+	LOGP(DRLCMACUL, LOGL_DEBUG, "- BSN %d storing in window (%d..%d)\n",
+		rh->bsn, tbf->dir.ul.v_q,
+		(tbf->dir.ul.v_q + tbf->ws - 1) & mod_sns);
+	/* Raise V(R) to highest received sequence number not received. */
+	offset_v_r = (rh->bsn + 1 - tbf->dir.ul.v_r) & mod_sns;
+	if (offset_v_r < (tbf->sns >> 1)) { /* Positive offset, so raise. */
+		while (offset_v_r--) {
+			if (offset_v_r) /* all except the received block */
+				tbf->dir.ul.v_n[tbf->dir.ul.v_r & mod_sns_half]
+					= 'N'; /* Mark block as not received */
+			tbf->dir.ul.v_r = (tbf->dir.ul.v_r + 1) & mod_sns;
+				/* Inc V(R). */
+		}
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- Raising V(R) to %d\n",
+			tbf->dir.ul.v_r);
+	}
+
+	/* Raise V(Q) if possible, and retrieve LLC frames from blocks.
+	 * This is looped until there is a gap (non received block) or
+	 * the window is empty.*/
+	while (tbf->dir.ul.v_q != tbf->dir.ul.v_r && tbf->dir.ul.v_n[
+			(index = tbf->dir.ul.v_q & mod_sns_half)] == 'R') {
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- Taking block %d out, raising "
+			"V(Q) to %d\n", tbf->dir.ul.v_q,
+			(tbf->dir.ul.v_q + 1) & mod_sns);
+		/* get LLC data from block */
+		tbf->assemble_forward_llc(tbf->rlc_block[index], tbf->rlc_block_len[index]);
+		/* raise V(Q), because block already received */
+		tbf->dir.ul.v_q = (tbf->dir.ul.v_q + 1) & mod_sns;
+	}
+
+	/* Check CV of last frame in buffer */
+	if (tbf->state_is(GPRS_RLCMAC_FLOW) /* still in flow state */
+	 && tbf->dir.ul.v_q == tbf->dir.ul.v_r) { /* if complete */
+		struct rlc_ul_header *last_rh = (struct rlc_ul_header *)
+			tbf->rlc_block[(tbf->dir.ul.v_r - 1) & mod_sns_half];
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- No gaps in received block, "
+			"last block: BSN=%d CV=%d\n", last_rh->bsn,
+			last_rh->cv);
+		if (last_rh->cv == 0) {
+			LOGP(DRLCMACUL, LOGL_DEBUG, "- Finished with UL "
+				"TBF\n");
+			tbf_new_state(tbf, GPRS_RLCMAC_FINISHED);
+			/* Reset N3103 counter. */
+			tbf->dir.ul.n3103 = 0;
+		}
+	}
+
+	/* If TLLI is included or if we received half of the window, we send
+	 * an ack/nack */
+	if (rh->si || rh->ti || tbf->state_is(GPRS_RLCMAC_FINISHED)
+	 || (tbf->dir.ul.rx_counter % SEND_ACK_AFTER_FRAMES) == 0) {
+		if (rh->si) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "- Scheduling Ack/Nack, "
+				"because MS is stalled.\n");
+		}
+		if (rh->ti) {
+			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
+				"because TLLI is included.\n");
+		}
+		if (tbf->state_is(GPRS_RLCMAC_FINISHED)) {
+			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
+				"because last block has CV==0.\n");
+		}
+		if ((tbf->dir.ul.rx_counter % SEND_ACK_AFTER_FRAMES) == 0) {
+			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
+				"because %d frames received.\n",
+				SEND_ACK_AFTER_FRAMES);
+		}
+		if (tbf->ul_ack_state == GPRS_RLCMAC_UL_ACK_NONE) {
+#ifdef DEBUG_DIAGRAM
+			if (rh->si)
+				debug_diagram(bts->bts, tbf->diag, "sched UL-ACK stall");
+			if (rh->ti)
+				debug_diagram(bts->bts, tbf->diag, "sched UL-ACK TLLI");
+			if (tbf->state_is(GPRS_RLCMAC_FINISHED))
+				debug_diagram(bts->bts, tbf->diag, "sched UL-ACK CV==0");
+			if ((tbf->dir.ul.rx_counter % SEND_ACK_AFTER_FRAMES) == 0)
+				debug_diagram(bts->bts, tbf->diag, "sched UL-ACK n=%d",
+					tbf->dir.ul.rx_counter);
+#endif
+			/* trigger sending at next RTS */
+			tbf->ul_ack_state = GPRS_RLCMAC_UL_ACK_SEND_ACK;
+		} else {
+			/* already triggered */
+			LOGP(DRLCMACUL, LOGL_DEBUG, "-  Sending Ack/Nack is "
+				"already triggered, don't schedule!\n");
+		}
+	}
+
+	return 0;
+}
+
+
 /* received RLC/MAC block from L1 */
 int gprs_rlcmac_pdch::rcv_block(uint8_t *data, uint8_t len, uint32_t fn, int8_t rssi)
 {
@@ -351,8 +583,7 @@ int gprs_rlcmac_pdch::rcv_block(uint8_t *data, uint8_t len, uint32_t fn, int8_t
 
 	switch (payload) {
 	case GPRS_RLCMAC_DATA_BLOCK:
-		rc = gprs_rlcmac_rcv_data_block_acknowledged(bts, trx_no, ts_no, data,
-			len, rssi);
+		rc = rcv_data_block_acknowledged(bts, trx_no, ts_no, data, len, rssi);
 		break;
 	case GPRS_RLCMAC_CONTROL_BLOCK:
 		block = bitvec_alloc(len);
diff --git a/src/bts.h b/src/bts.h
index 4b9ede4..7eabfbc 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -70,6 +70,14 @@ struct gprs_rlcmac_pdch {
 	/* back pointers */
 	struct gprs_rlcmac_trx *trx;
 	uint8_t ts_no;
+
+#ifdef __cplusplus
+private:
+	int rcv_data_block_acknowledged(struct gprs_rlcmac_bts *bts,
+				uint8_t trx, uint8_t ts,
+				uint8_t *data, uint8_t len, int8_t rssi);
+
+#endif
 };
 
 struct gprs_rlcmac_trx {
diff --git a/src/decoding.cpp b/src/decoding.cpp
new file mode 100644
index 0000000..596b66e
--- /dev/null
+++ b/src/decoding.cpp
@@ -0,0 +1,70 @@
+/* decoding
+ *
+ * Copyright (C) 2012 Ivan Klyuchnikov
+ * Copyright (C) 2012 Andreas Eversberg <jolly@eversberg.eu>
+ *
+ * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+#include <decoding.h>
+#include <rlc.h>
+#include <gprs_debug.h>
+
+#include <arpa/inet.h>
+
+#include <errno.h>
+#include <string.h>
+
+
+int Decoding::tlli_from_ul_data(const uint8_t *data, uint8_t len,
+					uint32_t *tlli)
+{
+	struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
+	struct rlc_li_field *li;
+	uint8_t e;
+	uint32_t _tlli;
+
+	if (!rh->ti)
+		return -EINVAL;
+	
+	data += 3;
+	len -= 3;
+	e = rh->e;
+	/* if E is not set (LI follows) */
+	while (!e) {
+		if (!len) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA LI extended, "
+				"but no more data\n");
+			return -EINVAL;
+		}
+		/* get new E */
+		li = (struct rlc_li_field *)data;
+		if (li->e == 0) /* if LI==0, E is interpreted as '1' */
+			e = 1;
+		else
+			e = li->e;
+		data++;
+		len--;
+	}
+	if (len < 4) {
+		LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TLLI out of frame "
+			"border\n");
+		return -EINVAL;
+	}
+	memcpy(&_tlli, data, 4);
+	*tlli = ntohl(_tlli);
+
+	return 0;
+}
+
diff --git a/src/decoding.h b/src/decoding.h
new file mode 100644
index 0000000..47983a2
--- /dev/null
+++ b/src/decoding.h
@@ -0,0 +1,28 @@
+/* decoding
+ *
+ * Copyright (C) 2012 Ivan Klyuchnikov
+ * Copyright (C) 2012 Andreas Eversberg <jolly@eversberg.eu>
+ *
+ * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+#pragma once
+
+#include <stdint.h>
+
+class Decoding {
+public:
+	static int tlli_from_ul_data(const uint8_t *data, uint8_t len,
+					uint32_t *tlli);
+};
diff --git a/src/gprs_rlcmac.h b/src/gprs_rlcmac.h
index 081271d..af15e77 100644
--- a/src/gprs_rlcmac.h
+++ b/src/gprs_rlcmac.h
@@ -119,10 +119,6 @@ int gprs_rlcmac_downlink_ack(
 int gprs_rlcmac_paging_request(uint8_t *ptmsi, uint16_t ptmsi_len,
 	const char *imsi);
 
-int gprs_rlcmac_rcv_data_block_acknowledged(struct gprs_rlcmac_bts *bts,
-	uint8_t trx, uint8_t ts,
-	uint8_t *data, uint8_t len, int8_t rssi);
-
 struct msgb *gprs_rlcmac_send_data_block_acknowledged(
         struct gprs_rlcmac_tbf *tbf, uint32_t fn, uint8_t ts);
 
diff --git a/src/gprs_rlcmac_data.cpp b/src/gprs_rlcmac_data.cpp
index 324e2b9..f2887b2 100644
--- a/src/gprs_rlcmac_data.cpp
+++ b/src/gprs_rlcmac_data.cpp
@@ -24,6 +24,7 @@
 #include <bts.h>
 #include <encoding.h>
 #include <tbf.h>
+#include <rlc.h>
 
 static struct gprs_rlcmac_cs gprs_rlcmac_cs[] = {
 /*	frame length	data block	max payload */
@@ -37,9 +38,6 @@ static struct gprs_rlcmac_cs gprs_rlcmac_cs[] = {
 
 extern void *tall_pcu_ctx;
 
-/* After receiving these frames, we send ack/nack. */
-#define SEND_ACK_AFTER_FRAMES 20
-
 /* After sending these frames, we poll for ack/nack. */
 #define POLL_ACK_AFTER_FRAMES 20
 
@@ -47,39 +45,6 @@ extern void *tall_pcu_ctx;
 #define POLLING_ASSIGNMENT_DL 1
 #define POLLING_ASSIGNMENT_UL 1
 
-extern "C" {
-/* TS 04.60  10.2.2 */
-struct rlc_ul_header {
-	uint8_t	r:1,
-		 si:1,
-		 cv:4,
-		 pt:2;
-	uint8_t	ti:1,
-		 tfi:5,
-		 pi:1,
-		 spare:1;
-	uint8_t	e:1,
-		 bsn:7;
-} __attribute__ ((packed));
-
-struct rlc_dl_header {
-	uint8_t	usf:3,
-		 s_p:1,
-		 rrbp:2,
-		 pt:2;
-	uint8_t	fbi:1,
-		 tfi:5,
-		 pr:2;
-	uint8_t	e:1,
-		 bsn:7;
-} __attribute__ ((packed));
-
-struct rlc_li_field {
-	uint8_t	e:1,
-		 m:1,
-		 li:6;
-} __attribute__ ((packed));
-}
 
 static void gprs_rlcmac_downlink_assignment(
 	gprs_rlcmac_tbf *tbf, uint8_t poll,
@@ -469,212 +434,6 @@ int gprs_rlcmac_rcv_control_block(struct gprs_rlcmac_bts *bts,
  * UL data block flow
  */
 
-/* get TLLI from received UL data block */
-static int tlli_from_ul_data(uint8_t *data, uint8_t len, uint32_t *tlli)
-{
-	struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
-	struct rlc_li_field *li;
-	uint8_t e;
-	uint32_t _tlli;
-
-	if (!rh->ti)
-		return -EINVAL;
-	
-	data += 3;
-	len -= 3;
-	e = rh->e;
-	/* if E is not set (LI follows) */
-	while (!e) {
-		if (!len) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA LI extended, "
-				"but no more data\n");
-			return -EINVAL;
-		}
-		/* get new E */
-		li = (struct rlc_li_field *)data;
-		if (li->e == 0) /* if LI==0, E is interpreted as '1' */
-			e = 1;
-		else
-			e = li->e;
-		data++;
-		len--;
-	}
-	if (len < 4) {
-		LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TLLI out of frame "
-			"border\n");
-		return -EINVAL;
-	}
-	memcpy(&_tlli, data, 4);
-	*tlli = ntohl(_tlli);
-
-	return 0;
-}
-
-/* Store received block data in LLC message(s) and forward to SGSN if complete.
- */
-static int gprs_rlcmac_assemble_llc(struct gprs_rlcmac_tbf *tbf, uint8_t *data,
-	uint8_t len)
-{
-	struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
-	uint8_t e, m;
-	struct rlc_li_field *li;
-	uint8_t frame_offset[16], offset = 0, chunk;
-	int i, frames = 0;
-
-	LOGP(DRLCMACUL, LOGL_DEBUG, "- Assembling frames: (len=%d)\n", len);
-	
-	data += 3;
-	len -= 3;
-	e = rh->e; /* if extended */
-	m = 1; /* more frames, that means: the first frame */
-
-	/* Parse frame offsets from length indicator(s), if any. */
-	while (1) {
-		if (frames == (int)sizeof(frame_offset)) {
-			LOGP(DRLCMACUL, LOGL_ERROR, "Too many frames in "
-				"block\n");
-			return -EINVAL;
-		}
-		frame_offset[frames++] = offset;
-		LOGP(DRLCMACUL, LOGL_DEBUG, "-- Frame %d starts at offset "
-			"%d\n", frames, offset);
-		if (!len)
-			break;
-		/* M == 0 and E == 0 is not allowed in this version. */
-		if (!m && !e) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TBF=%d "
-				"ignored, because M='0' and E='0'.\n",
-				tbf->tfi);
-			return 0;
-		}
-		/* no more frames in this segment */
-		if (e) {
-			break;
-		}
-		/* There is a new frame and an LI that delimits it. */
-		if (m) {
-			li = (struct rlc_li_field *)data;
-			LOGP(DRLCMACUL, LOGL_DEBUG, "-- Delimiter len=%d\n",
-				li->li);
-			/* Special case: LI == 0
-			 * If the last segment would fit precisely into the
-			 * rest of the RLC MAC block, there would be no way
-			 * to delimit that this segment ends and is not
-			 * continued in the next block.
-			 * The special LI (0) is used to force the segment to
-			 * extend into the next block, so it is delimited there.
-			 * This LI must be skipped. Also it is the last LI.
-			 */
-			if (li->li == 0) {
-				data++;
-				len--;
-				m = 1; /* M is ignored, we know there is more */
-				break; /* handle E as '1', so we break! */
-			}
-			e = li->e;
-			m = li->m;
-			offset += li->li;
-			data++;
-			len--;
-			continue;
-		}
-	}
-	if (!m) {
-		LOGP(DRLCMACUL, LOGL_DEBUG, "- Last frame carries spare "
-			"data\n");
-	}
-
-	LOGP(DRLCMACUL, LOGL_DEBUG, "- Data length after length fields: %d\n",
-		len);
-	/* TLLI */
-	if (rh->ti) {
-		if (len < 4) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TLLI out of "
-				"frame border\n");
-			return -EINVAL;
-		}
-		data += 4;
-		len -= 4;
-		LOGP(DRLCMACUL, LOGL_DEBUG, "- Length after skipping TLLI: "
-			"%d\n", len);
-	}
-
-	/* PFI */
-	if (rh->pi) {
-		LOGP(DRLCMACUL, LOGL_ERROR, "ERROR: PFI not supported, "
-			"please disable in SYSTEM INFORMATION\n");
-		if (len < 1) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA PFI out of "
-				"frame border\n");
-			return -EINVAL;
-		}
-		data++;
-		len--;
-		LOGP(DRLCMACUL, LOGL_DEBUG, "- Length after skipping PFI: "
-			"%d\n", len);
-	}
-
-	/* Now we have:
-	 * - a list of frames offsets: frame_offset[]
-	 * - number of frames: i
-	 * - m == 0: Last frame carries spare data (end of TBF).
-	 */
-
-	/* Check if last offset would exceed frame. */
-	if (offset > len) {
-		LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TBF=%d ignored, "
-			"because LI delimits data that exceeds block size.\n",
-			tbf->tfi);
-		return -EINVAL;
-	}
-
-	/* create LLC frames */
-	for (i = 0; i < frames; i++) {
-		/* last frame ? */
-		if (i == frames - 1) {
-			/* no more data in last frame */
-			if (!m)
-				break;
-			/* data until end of frame */
-			chunk = len - frame_offset[i];
-		} else {
-			/* data until next frame */
-			chunk = frame_offset[i + 1] - frame_offset[i];
-		}
-		LOGP(DRLCMACUL, LOGL_DEBUG, "-- Appending chunk (len=%d) to "
-			"frame at %d.\n", chunk, tbf->llc_index);
-		if (tbf->llc_index + chunk > LLC_MAX_LEN) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "LLC frame exceeds "
-				"maximum size.\n");
-			chunk = LLC_MAX_LEN - tbf->llc_index;
-		}
-		memcpy(tbf->llc_frame + tbf->llc_index, data + frame_offset[i],
-			chunk);
-		tbf->llc_index += chunk;
-		/* not last frame. */
-		if (i != frames - 1) {
-			/* send frame to SGSN */
-			LOGP(DRLCMACUL, LOGL_INFO, "Complete UL frame for "
-				"TBF=%d: len=%d\n", tbf->tfi, tbf->llc_index);
-			gprs_rlcmac_tx_ul_ud(tbf);
-			tbf->llc_index = 0; /* reset frame space */
-		/* also check if CV==0, because the frame may fill up the
-		 * block precisely, then it is also complete. normally the
-		 * frame would be extended into the next block with a 0-length
-		 * delimiter added to this block. */
-		} else if (rh->cv == 0) {
-			/* send frame to SGSN */
-			LOGP(DRLCMACUL, LOGL_INFO, "Complete UL frame for "
-				"TBF=%d that fits precisely in last block: "
-				"len=%d\n", tbf->tfi, tbf->llc_index);
-			gprs_rlcmac_tx_ul_ud(tbf);
-			tbf->llc_index = 0; /* reset frame space */
-		}
-	}
-
-	return 0;
-}
-
 struct msgb *gprs_rlcmac_send_uplink_ack(
 	struct gprs_rlcmac_tbf *tbf,
 	uint32_t fn)
@@ -731,228 +490,6 @@ struct msgb *gprs_rlcmac_send_uplink_ack(
 	return msg;
 }
 
-/* receive UL data block
- *
- * The blocks are defragmented and forwarded as LLC frames, if complete.
- */
-int gprs_rlcmac_rcv_data_block_acknowledged(struct gprs_rlcmac_bts *bts,
-	uint8_t trx, uint8_t ts,
-	uint8_t *data, uint8_t len, int8_t rssi)
-{
-	struct gprs_rlcmac_tbf *tbf;
-	struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
-	uint16_t mod_sns, mod_sns_half, offset_v_q, offset_v_r, index;
-	int rc;
-
-	switch (len) {
-		case 54:
-			/* omitting spare bits */
-			len = 53;
-			break;
-		case 40:
-			/* omitting spare bits */
-			len = 39;
-			break;
-		case 34:
-			/* omitting spare bits */
-			len = 33;
-			break;
-		case 23:
-			break;
-	default:
-		LOGP(DRLCMACUL, LOGL_ERROR, "Dropping data block with invalid"
-			"length: %d)\n", len);
-		return -EINVAL;
-	}
-
-	/* find TBF inst from given TFI */
-	tbf = tbf_by_tfi(bts, rh->tfi, trx, GPRS_RLCMAC_UL_TBF);
-	if (!tbf) {
-		LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA unknown TBF=%d\n",
-			rh->tfi);
-		return 0;
-	}
-	tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_UL_DATA);
-
-	LOGP(DRLCMACUL, LOGL_DEBUG, "UL DATA TBF=%d received (V(Q)=%d .. "
-		"V(R)=%d)\n", rh->tfi, tbf->dir.ul.v_q, tbf->dir.ul.v_r);
-
-	/* process RSSI */
-	gprs_rlcmac_rssi(tbf, rssi);
-
-	/* get TLLI */
-	if (!tbf->tlli_valid) {
-		struct gprs_rlcmac_tbf *dl_tbf, *ul_tbf;
-
-		/* no TLLI yet */
-		if (!rh->ti) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TBF=%d without "
-				"TLLI, but no TLLI received yet\n", rh->tfi);
-			return 0;
-		}
-		rc = tlli_from_ul_data(data, len, &tbf->tlli);
-		if (rc) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "Failed to decode TLLI "
-				"of UL DATA TBF=%d.\n", rh->tfi);
-			return 0;
-		}
-		LOGP(DRLCMACUL, LOGL_INFO, "Decoded premier TLLI=0x%08x of "
-			"UL DATA TBF=%d.\n", tbf->tlli, rh->tfi);
-		if ((dl_tbf = bts->bts->tbf_by_tlli(tbf->tlli, GPRS_RLCMAC_DL_TBF))) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "Got RACH from "
-				"TLLI=0x%08x while DL TBF=%d still exists. "
-				"Killing pending DL TBF\n", tbf->tlli,
-				dl_tbf->tfi);
-			tbf_free(dl_tbf);
-		}
-		/* tbf_by_tlli will not find your TLLI, because it is not
-		 * yet marked valid */
-		if ((ul_tbf = bts->bts->tbf_by_tlli(tbf->tlli, GPRS_RLCMAC_UL_TBF))) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "Got RACH from "
-				"TLLI=0x%08x while UL TBF=%d still exists. "
-				"Killing pending UL TBF\n", tbf->tlli,
-				ul_tbf->tfi);
-			tbf_free(ul_tbf);
-		}
-		/* mark TLLI valid now */
-		tbf->tlli_valid = 1;
-		/* store current timing advance */
-		bts->bts->timing_advance()->remember(tbf->tlli, tbf->ta);
-	/* already have TLLI, but we stille get another one */
-	} else if (rh->ti) {
-		uint32_t tlli;
-		rc = tlli_from_ul_data(data, len, &tlli);
-		if (rc) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "Failed to decode TLLI "
-				"of UL DATA TBF=%d.\n", rh->tfi);
-			return 0;
-		}
-		if (tlli != tbf->tlli) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "TLLI mismatch on UL "
-				"DATA TBF=%d. (Ignoring due to contention "
-				"resolution)\n", rh->tfi);
-			return 0;
-		}
-	}
-
-	mod_sns = tbf->sns - 1;
-	mod_sns_half = (tbf->sns >> 1) - 1;
-
-	/* restart T3169 */
-	tbf_timer_start(tbf, 3169, bts->t3169, 0);
-
-	/* Increment RX-counter */
-	tbf->dir.ul.rx_counter++;
-
-	/* current block relative to lowest unreceived block */
-	offset_v_q = (rh->bsn - tbf->dir.ul.v_q) & mod_sns;
-	/* If out of window (may happen if blocks below V(Q) are received
-	 * again. */
-	if (offset_v_q >= tbf->ws) {
-		LOGP(DRLCMACUL, LOGL_DEBUG, "- BSN %d out of window "
-			"%d..%d (it's normal)\n", rh->bsn, tbf->dir.ul.v_q,
-			(tbf->dir.ul.v_q + tbf->ws - 1) & mod_sns);
-		return 0;
-	}
-	/* Write block to buffer and set receive state array. */
-	index = rh->bsn & mod_sns_half; /* memory index of block */
-	memcpy(tbf->rlc_block[index], data, len); /* Copy block. */
-	tbf->rlc_block_len[index] = len;
-	tbf->dir.ul.v_n[index] = 'R'; /* Mark received block. */
-	LOGP(DRLCMACUL, LOGL_DEBUG, "- BSN %d storing in window (%d..%d)\n",
-		rh->bsn, tbf->dir.ul.v_q,
-		(tbf->dir.ul.v_q + tbf->ws - 1) & mod_sns);
-	/* Raise V(R) to highest received sequence number not received. */
-	offset_v_r = (rh->bsn + 1 - tbf->dir.ul.v_r) & mod_sns;
-	if (offset_v_r < (tbf->sns >> 1)) { /* Positive offset, so raise. */
-		while (offset_v_r--) {
-			if (offset_v_r) /* all except the received block */
-				tbf->dir.ul.v_n[tbf->dir.ul.v_r & mod_sns_half]
-					= 'N'; /* Mark block as not received */
-			tbf->dir.ul.v_r = (tbf->dir.ul.v_r + 1) & mod_sns;
-				/* Inc V(R). */
-		}
-		LOGP(DRLCMACUL, LOGL_DEBUG, "- Raising V(R) to %d\n",
-			tbf->dir.ul.v_r);
-	}
-
-	/* Raise V(Q) if possible, and retrieve LLC frames from blocks.
-	 * This is looped until there is a gap (non received block) or
-	 * the window is empty.*/
-	while (tbf->dir.ul.v_q != tbf->dir.ul.v_r && tbf->dir.ul.v_n[
-			(index = tbf->dir.ul.v_q & mod_sns_half)] == 'R') {
-		LOGP(DRLCMACUL, LOGL_DEBUG, "- Taking block %d out, raising "
-			"V(Q) to %d\n", tbf->dir.ul.v_q,
-			(tbf->dir.ul.v_q + 1) & mod_sns);
-		/* get LLC data from block */
-		gprs_rlcmac_assemble_llc(tbf, tbf->rlc_block[index],
-			tbf->rlc_block_len[index]);
-		/* raise V(Q), because block already received */
-		tbf->dir.ul.v_q = (tbf->dir.ul.v_q + 1) & mod_sns;
-	}
-
-	/* Check CV of last frame in buffer */
-	if (tbf->state_is(GPRS_RLCMAC_FLOW) /* still in flow state */
-	 && tbf->dir.ul.v_q == tbf->dir.ul.v_r) { /* if complete */
-		struct rlc_ul_header *last_rh = (struct rlc_ul_header *)
-			tbf->rlc_block[(tbf->dir.ul.v_r - 1) & mod_sns_half];
-		LOGP(DRLCMACUL, LOGL_DEBUG, "- No gaps in received block, "
-			"last block: BSN=%d CV=%d\n", last_rh->bsn,
-			last_rh->cv);
-		if (last_rh->cv == 0) {
-			LOGP(DRLCMACUL, LOGL_DEBUG, "- Finished with UL "
-				"TBF\n");
-			tbf_new_state(tbf, GPRS_RLCMAC_FINISHED);
-			/* Reset N3103 counter. */
-			tbf->dir.ul.n3103 = 0;
-		}
-	}
-
-	/* If TLLI is included or if we received half of the window, we send
-	 * an ack/nack */
-	if (rh->si || rh->ti || tbf->state_is(GPRS_RLCMAC_FINISHED)
-	 || (tbf->dir.ul.rx_counter % SEND_ACK_AFTER_FRAMES) == 0) {
-		if (rh->si) {
-			LOGP(DRLCMACUL, LOGL_NOTICE, "- Scheduling Ack/Nack, "
-				"because MS is stalled.\n");
-		}
-		if (rh->ti) {
-			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
-				"because TLLI is included.\n");
-		}
-		if (tbf->state_is(GPRS_RLCMAC_FINISHED)) {
-			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
-				"because last block has CV==0.\n");
-		}
-		if ((tbf->dir.ul.rx_counter % SEND_ACK_AFTER_FRAMES) == 0) {
-			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
-				"because %d frames received.\n",
-				SEND_ACK_AFTER_FRAMES);
-		}
-		if (tbf->ul_ack_state == GPRS_RLCMAC_UL_ACK_NONE) {
-#ifdef DEBUG_DIAGRAM
-			if (rh->si)
-				debug_diagram(bts->bts, tbf->diag, "sched UL-ACK stall");
-			if (rh->ti)
-				debug_diagram(bts->bts, tbf->diag, "sched UL-ACK TLLI");
-			if (tbf->state_is(GPRS_RLCMAC_FINISHED))
-				debug_diagram(bts->bts, tbf->diag, "sched UL-ACK CV==0");
-			if ((tbf->dir.ul.rx_counter % SEND_ACK_AFTER_FRAMES) == 0)
-				debug_diagram(bts->bts, tbf->diag, "sched UL-ACK n=%d",
-					tbf->dir.ul.rx_counter);
-#endif
-			/* trigger sending at next RTS */
-			tbf->ul_ack_state = GPRS_RLCMAC_UL_ACK_SEND_ACK;
-		} else {
-			/* already triggered */
-			LOGP(DRLCMACUL, LOGL_DEBUG, "-  Sending Ack/Nack is "
-				"already triggered, don't schedule!\n");
-		}
-	}
-
-	return 0;
-}
-
 struct msgb *gprs_rlcmac_send_packet_uplink_assignment(
 	struct gprs_rlcmac_tbf *tbf, uint32_t fn)
 {
diff --git a/src/rlc.h b/src/rlc.h
new file mode 100644
index 0000000..df10ec3
--- /dev/null
+++ b/src/rlc.h
@@ -0,0 +1,56 @@
+/* rlc header descriptions
+ *
+ * Copyright (C) 2012 Ivan Klyuchnikov
+ * Copyright (C) 2012 Andreas Eversberg <jolly@eversberg.eu>
+ *
+ * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+#pragma once
+
+#include <stdint.h>
+
+extern "C" {
+/* TS 04.60  10.2.2 */
+struct rlc_ul_header {
+	uint8_t	r:1,
+		 si:1,
+		 cv:4,
+		 pt:2;
+	uint8_t	ti:1,
+		 tfi:5,
+		 pi:1,
+		 spare:1;
+	uint8_t	e:1,
+		 bsn:7;
+} __attribute__ ((packed));
+
+struct rlc_dl_header {
+	uint8_t	usf:3,
+		 s_p:1,
+		 rrbp:2,
+		 pt:2;
+	uint8_t	fbi:1,
+		 tfi:5,
+		 pr:2;
+	uint8_t	e:1,
+		 bsn:7;
+} __attribute__ ((packed));
+
+struct rlc_li_field {
+	uint8_t	e:1,
+		 m:1,
+		 li:6;
+} __attribute__ ((packed));
+}
diff --git a/src/tbf.cpp b/src/tbf.cpp
index 683b33a..259e461 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -21,6 +21,7 @@
 
 #include <bts.h>
 #include <tbf.h>
+#include <rlc.h>
 #include <gprs_rlcmac.h>
 #include <gprs_debug.h>
 
@@ -626,6 +627,172 @@ void gprs_rlcmac_tbf::update_llc_frame(struct msgb *msg)
 	llc_length = msg->len;
 }
 
+/*
+ * Store received block data in LLC message(s) and forward to SGSN
+ * if complete.
+ */
+int gprs_rlcmac_tbf::assemble_forward_llc(uint8_t *data, uint8_t len)
+{
+	struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
+	uint8_t e, m;
+	struct rlc_li_field *li;
+	uint8_t frame_offset[16], offset = 0, chunk;
+	int i, frames = 0;
+
+	LOGP(DRLCMACUL, LOGL_DEBUG, "- Assembling frames: (len=%d)\n", len);
+
+	data += 3;
+	len -= 3;
+	e = rh->e; /* if extended */
+	m = 1; /* more frames, that means: the first frame */
+
+	/* Parse frame offsets from length indicator(s), if any. */
+	while (1) {
+		if (frames == (int)sizeof(frame_offset)) {
+			LOGP(DRLCMACUL, LOGL_ERROR, "Too many frames in "
+				"block\n");
+			return -EINVAL;
+		}
+		frame_offset[frames++] = offset;
+		LOGP(DRLCMACUL, LOGL_DEBUG, "-- Frame %d starts at offset "
+			"%d\n", frames, offset);
+		if (!len)
+			break;
+		/* M == 0 and E == 0 is not allowed in this version. */
+		if (!m && !e) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TBF=%d "
+				"ignored, because M='0' and E='0'.\n",
+				this->tfi);
+			return 0;
+		}
+		/* no more frames in this segment */
+		if (e) {
+			break;
+		}
+		/* There is a new frame and an LI that delimits it. */
+		if (m) {
+			li = (struct rlc_li_field *)data;
+			LOGP(DRLCMACUL, LOGL_DEBUG, "-- Delimiter len=%d\n",
+				li->li);
+			/* Special case: LI == 0
+			 * If the last segment would fit precisely into the
+			 * rest of the RLC MAC block, there would be no way
+			 * to delimit that this segment ends and is not
+			 * continued in the next block.
+			 * The special LI (0) is used to force the segment to
+			 * extend into the next block, so it is delimited there.
+			 * This LI must be skipped. Also it is the last LI.
+			 */
+			if (li->li == 0) {
+				data++;
+				len--;
+				m = 1; /* M is ignored, we know there is more */
+				break; /* handle E as '1', so we break! */
+			}
+			e = li->e;
+			m = li->m;
+			offset += li->li;
+			data++;
+			len--;
+			continue;
+		}
+	}
+	if (!m) {
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- Last frame carries spare "
+			"data\n");
+	}
+
+	LOGP(DRLCMACUL, LOGL_DEBUG, "- Data length after length fields: %d\n",
+		len);
+	/* TLLI */
+	if (rh->ti) {
+		if (len < 4) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TLLI out of "
+				"frame border\n");
+			return -EINVAL;
+		}
+		data += 4;
+		len -= 4;
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- Length after skipping TLLI: "
+			"%d\n", len);
+	}
+
+	/* PFI */
+	if (rh->pi) {
+		LOGP(DRLCMACUL, LOGL_ERROR, "ERROR: PFI not supported, "
+			"please disable in SYSTEM INFORMATION\n");
+		if (len < 1) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA PFI out of "
+				"frame border\n");
+			return -EINVAL;
+		}
+		data++;
+		len--;
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- Length after skipping PFI: "
+			"%d\n", len);
+	}
+
+	/* Now we have:
+	 * - a list of frames offsets: frame_offset[]
+	 * - number of frames: i
+	 * - m == 0: Last frame carries spare data (end of TBF).
+	 */
+
+	/* Check if last offset would exceed frame. */
+	if (offset > len) {
+		LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TBF=%d ignored, "
+			"because LI delimits data that exceeds block size.\n",
+			this->tfi);
+		return -EINVAL;
+	}
+
+	/* create LLC frames */
+	for (i = 0; i < frames; i++) {
+		/* last frame ? */
+		if (i == frames - 1) {
+			/* no more data in last frame */
+			if (!m)
+				break;
+			/* data until end of frame */
+			chunk = len - frame_offset[i];
+		} else {
+			/* data until next frame */
+			chunk = frame_offset[i + 1] - frame_offset[i];
+		}
+		LOGP(DRLCMACUL, LOGL_DEBUG, "-- Appending chunk (len=%d) to "
+			"frame at %d.\n", chunk, this->llc_index);
+		if (this->llc_index + chunk > LLC_MAX_LEN) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "LLC frame exceeds "
+				"maximum size.\n");
+			chunk = LLC_MAX_LEN - this->llc_index;
+		}
+		memcpy(this->llc_frame + this->llc_index, data + frame_offset[i],
+			chunk);
+		this->llc_index += chunk;
+		/* not last frame. */
+		if (i != frames - 1) {
+			/* send frame to SGSN */
+			LOGP(DRLCMACUL, LOGL_INFO, "Complete UL frame for "
+				"TBF=%d: len=%d\n", this->tfi, this->llc_index);
+			gprs_rlcmac_tx_ul_ud(this);
+			this->llc_index = 0; /* reset frame space */
+		/* also check if CV==0, because the frame may fill up the
+		 * block precisely, then it is also complete. normally the
+		 * frame would be extended into the next block with a 0-length
+		 * delimiter added to this block. */
+		} else if (rh->cv == 0) {
+			/* send frame to SGSN */
+			LOGP(DRLCMACUL, LOGL_INFO, "Complete UL frame for "
+				"TBF=%d that fits precisely in last block: "
+				"len=%d\n", this->tfi, this->llc_index);
+			gprs_rlcmac_tx_ul_ud(this);
+			this->llc_index = 0; /* reset frame space */
+		}
+	}
+
+	return 0;
+}
+
 void gprs_rlcmac_tbf::free_all(struct gprs_rlcmac_trx *trx)
 {
 	for (uint8_t tfi = 0; tfi < 32; tfi++) {
diff --git a/src/tbf.h b/src/tbf.h
index 0441096..10bff14 100644
--- a/src/tbf.h
+++ b/src/tbf.h
@@ -96,6 +96,9 @@ struct gprs_rlcmac_tbf {
 	struct msgb *llc_dequeue(bssgp_bvc_ctx *bctx);
 	void update_llc_frame(struct msgb *msg);
 
+	/* TODO: extract LLC class? */
+	int assemble_forward_llc(uint8_t *data, uint8_t len);
+
 	int rlcmac_diag();
 
 	struct llist_head list;