tbf: Split out UL/DL TBF methods into separate files

tbf_ul.cpp for UL TBF methods
tbf_dl.cpp for DL TBF methods

This commit contains no code changes.

Ticket: SYS#389
Sponsored by: On-Waves ehf

1 files changed, 671 insertions, 0 deletions

diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
new file mode 100644
index 00000000..8abea201
--- /dev/null
+++ b/src/tbf_dl.cpp
@@ -0,0 +1,671 @@
+/* Copied from tbf.cpp
+ *
+ * Copyright (C) 2012 Ivan Klyuchnikov
+ * Copyright (C) 2012 Andreas Eversberg <jolly@eversberg.eu>
+ * Copyright (C) 2013 by Holger Hans Peter Freyther
+ *
+ * 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 <bts.h>
+#include <tbf.h>
+#include <rlc.h>
+#include <gprs_rlcmac.h>
+#include <gprs_debug.h>
+#include <gprs_bssgp_pcu.h>
+#include <decoding.h>
+
+extern "C" {
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/talloc.h>
+}
+
+#include <errno.h>
+#include <string.h>
+
+/* After sending these frames, we poll for ack/nack. */
+#define POLL_ACK_AFTER_FRAMES 20
+
+
+static const struct gprs_rlcmac_cs gprs_rlcmac_cs[] = {
+/*	frame length	data block	max payload */
+	{ 0,		0,		0  },
+	{ 23,		23,		20 }, /* CS-1 */
+	{ 34,		33,		30 }, /* CS-2 */
+	{ 40,		39,		36 }, /* CS-3 */
+	{ 54,		53,		50 }, /* CS-4 */
+};
+
+extern "C" {
+int bssgp_tx_llc_discarded(struct bssgp_bvc_ctx *bctx, uint32_t tlli,
+                           uint8_t num_frames, uint32_t num_octets);
+}
+
+static inline void tbf_update_ms_class(struct gprs_rlcmac_tbf *tbf,
+					const uint8_t ms_class)
+{
+	if (!tbf->ms_class && ms_class)
+		tbf->ms_class = ms_class;
+}
+
+int gprs_rlcmac_dl_tbf::append_data(const uint8_t ms_class,
+				const uint16_t pdu_delay_csec,
+				const uint8_t *data, const uint16_t len)
+{
+	LOGP(DRLCMAC, LOGL_INFO, "%s append\n", tbf_name(this));
+	if (state_is(GPRS_RLCMAC_WAIT_RELEASE)) {
+		LOGP(DRLCMAC, LOGL_DEBUG,
+			"%s in WAIT RELEASE state "
+			"(T3193), so reuse TBF\n", tbf_name(this));
+		tbf_update_ms_class(this, ms_class);
+		reuse_tbf(data, len);
+	} else {
+		/* the TBF exists, so we must write it in the queue
+		 * we prepend lifetime in front of PDU */
+		struct timeval *tv;
+		struct msgb *llc_msg = msgb_alloc(len + sizeof(*tv) * 2,
+			"llc_pdu_queue");
+		if (!llc_msg)
+			return -ENOMEM;
+		tv = (struct timeval *)msgb_put(llc_msg, sizeof(*tv));
+		gprs_llc::calc_pdu_lifetime(bts, pdu_delay_csec, tv);
+		tv = (struct timeval *)msgb_put(llc_msg, sizeof(*tv));
+		gettimeofday(tv, NULL);
+		memcpy(msgb_put(llc_msg, len), data, len);
+		m_llc.enqueue(llc_msg);
+		tbf_update_ms_class(this, ms_class);
+	}
+
+	return 0;
+}
+
+static struct gprs_rlcmac_dl_tbf *tbf_lookup_dl(BTS *bts,
+					const uint32_t tlli, const char *imsi)
+{
+	/* TODO: look up by IMSI first, then tlli, then old_tlli */
+	return bts->dl_tbf_by_tlli(tlli);
+}
+
+static int tbf_new_dl_assignment(struct gprs_rlcmac_bts *bts,
+				const char *imsi,
+				const uint32_t tlli, const uint8_t ms_class,
+				const uint8_t *data, const uint16_t len)
+{
+	uint8_t trx, ta, ss;
+	int8_t use_trx;
+	struct gprs_rlcmac_ul_tbf *ul_tbf, *old_ul_tbf;
+	struct gprs_rlcmac_dl_tbf *dl_tbf;
+	int8_t tfi; /* must be signed */
+	int rc;
+
+	/* check for uplink data, so we copy our informations */
+#warning "Do the same look up for IMSI, TLLI and OLD_TLLI"
+#warning "Refactor the below lines... into a new method"
+	ul_tbf = bts->bts->ul_tbf_by_tlli(tlli);
+	if (ul_tbf && ul_tbf->m_contention_resolution_done
+	 && !ul_tbf->m_final_ack_sent) {
+		use_trx = ul_tbf->trx->trx_no;
+		ta = ul_tbf->ta;
+		ss = 0;
+		old_ul_tbf = ul_tbf;
+	} else {
+		use_trx = -1;
+		/* we already have an uplink TBF, so we use that TA */
+		if (ul_tbf)
+			ta = ul_tbf->ta;
+		else {
+			/* recall TA */
+			rc = bts->bts->timing_advance()->recall(tlli);
+			if (rc < 0) {
+				LOGP(DRLCMAC, LOGL_NOTICE, "TA unknown"
+					", assuming 0\n");
+				ta = 0;
+			} else
+				ta = rc;
+		}
+		ss = 1; /* PCH assignment only allows one timeslot */
+		old_ul_tbf = NULL;
+	}
+
+	// Create new TBF (any TRX)
+#warning "Copy and paste with alloc_ul_tbf"
+	tfi = bts->bts->tfi_find_free(GPRS_RLCMAC_DL_TBF, &trx, use_trx);
+	if (tfi < 0) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH resource\n");
+		/* FIXME: send reject */
+		return -EBUSY;
+	}
+	/* set number of downlink slots according to multislot class */
+	dl_tbf = tbf_alloc_dl_tbf(bts, ul_tbf, tfi, trx, ms_class, ss);
+	if (!dl_tbf) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH resource\n");
+		/* FIXME: send reject */
+		return -EBUSY;
+	}
+	dl_tbf->m_tlli = tlli;
+	dl_tbf->m_tlli_valid = 1;
+	dl_tbf->ta = ta;
+
+	LOGP(DRLCMAC, LOGL_DEBUG, "%s [DOWNLINK] START\n", tbf_name(dl_tbf));
+
+	/* new TBF, so put first frame */
+	dl_tbf->m_llc.put_frame(data, len);
+	dl_tbf->bts->llc_frame_sched();
+
+	/* Store IMSI for later look-up and PCH retransmission */
+	dl_tbf->assign_imsi(imsi);
+
+	/* trigger downlink assignment and set state to ASSIGN.
+	 * we don't use old_downlink, so the possible uplink is used
+	 * to trigger downlink assignment. if there is no uplink,
+	 * AGCH is used. */
+	dl_tbf->bts->trigger_dl_ass(dl_tbf, old_ul_tbf, imsi);
+	return 0;
+}
+
+/**
+ * TODO: split into unit test-able parts...
+ */
+int gprs_rlcmac_dl_tbf::handle(struct gprs_rlcmac_bts *bts,
+		const uint32_t tlli, const char *imsi,
+		const uint8_t ms_class, const uint16_t delay_csec,
+		const uint8_t *data, const uint16_t len)
+{
+	struct gprs_rlcmac_dl_tbf *dl_tbf;
+
+	/* check for existing TBF */
+	dl_tbf = tbf_lookup_dl(bts->bts, tlli, imsi);
+	if (dl_tbf) {
+		int rc = dl_tbf->append_data(ms_class, delay_csec, data, len);
+		if (rc >= 0)
+			dl_tbf->assign_imsi(imsi);
+		return rc;
+	} 
+
+	return tbf_new_dl_assignment(bts, imsi, tlli, ms_class, data, len);
+}
+
+struct msgb *gprs_rlcmac_dl_tbf::llc_dequeue(bssgp_bvc_ctx *bctx)
+{
+	struct msgb *msg;
+	struct timeval *tv, tv_now;
+	uint32_t octets = 0, frames = 0;
+
+	gettimeofday(&tv_now, NULL);
+
+	while ((msg = m_llc.dequeue())) {
+		tv = (struct timeval *)msg->data;
+		msgb_pull(msg, sizeof(*tv));
+		msgb_pull(msg, sizeof(*tv));
+
+		if (gprs_llc::is_frame_expired(&tv_now, tv)) {
+			LOGP(DRLCMACDL, LOGL_NOTICE, "%s Discarding LLC PDU "
+				"because lifetime limit reached. Queue size %zu\n",
+				tbf_name(this), m_llc.m_queue_size);
+			bts->llc_timedout_frame();
+			frames++;
+			octets += msg->len;
+			msgb_free(msg);
+			continue;
+		}
+		break;
+	}
+
+	if (frames) {
+		if (frames > 0xff)
+			frames = 0xff;
+		if (octets > 0xffffff)
+			octets = 0xffffff;
+		bssgp_tx_llc_discarded(bctx, m_tlli, frames, octets);
+	}
+
+	return msg;
+}
+
+/*
+ * Create DL data block
+ * The messages are fragmented and forwarded as data blocks.
+ */
+struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(uint32_t fn, uint8_t ts)
+{
+	LOGP(DRLCMACDL, LOGL_DEBUG, "%s downlink (V(A)==%d .. "
+		"V(S)==%d)\n", tbf_name(this),
+		m_window.v_a(), m_window.v_s());
+
+do_resend:
+	/* check if there is a block with negative acknowledgement */
+	int resend_bsn = m_window.resend_needed();
+	if (resend_bsn >= 0) {
+		LOGP(DRLCMACDL, LOGL_DEBUG, "- Resending BSN %d\n", resend_bsn);
+		/* re-send block with negative aknowlegement */
+		m_window.m_v_b.mark_unacked(resend_bsn);
+		bts->rlc_resent();
+		return create_dl_acked_block(fn, ts, resend_bsn, false);
+	}
+
+	/* if the window has stalled, or transfer is complete,
+	 * send an unacknowledged block */
+	if (state_is(GPRS_RLCMAC_FINISHED) || dl_window_stalled()) {
+		if (state_is(GPRS_RLCMAC_FINISHED)) {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- Restarting at BSN %d, "
+				"because all blocks have been transmitted.\n",
+					m_window.v_a());
+			bts->rlc_restarted();
+		} else {
+			LOGP(DRLCMACDL, LOGL_NOTICE, "- Restarting at BSN %d, "
+				"because all window is stalled.\n",
+					m_window.v_a());
+			bts->rlc_stalled();
+		}
+		/* If V(S) == V(A) and finished state, we would have received
+		 * acknowledgement of all transmitted block. In this case we
+		 * would have transmitted the final block, and received ack
+		 * from MS. But in this case we did not receive the final ack
+		 * indication from MS. This should never happen if MS works
+		 * correctly. */
+		if (m_window.window_empty()) {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- MS acked all blocks, "
+				"so we re-transmit final block!\n");
+			/* we just send final block again */
+			int16_t index = m_window.v_s_mod(-1);
+			bts->rlc_resent();
+			return create_dl_acked_block(fn, ts, index, false);
+		}
+		
+		/* cycle through all unacked blocks */
+		int resend = m_window.mark_for_resend();
+
+		/* At this point there should be at least one unacked block
+		 * to be resent. If not, this is an software error. */
+		if (resend == 0) {
+			LOGP(DRLCMACDL, LOGL_ERROR, "Software error: "
+				"There are no unacknowledged blocks, but V(A) "
+				" != V(S). PLEASE FIX!\n");
+			/* we just send final block again */
+			int16_t index = m_window.v_s_mod(-1);
+			return create_dl_acked_block(fn, ts, index, false);
+		}
+		goto do_resend;
+	}
+
+	return create_new_bsn(fn, ts);
+}
+
+struct msgb *gprs_rlcmac_dl_tbf::create_new_bsn(const uint32_t fn, const uint8_t ts)
+{
+	struct rlc_dl_header *rh;
+	struct rlc_li_field *li;
+	struct msgb *msg;
+	uint8_t *delimiter, *data, *e_pointer;
+	uint16_t space, chunk;
+	gprs_rlc_data *rlc_data;
+	bool first_fin_ack = false;
+	const uint16_t bsn = m_window.v_s();
+
+	LOGP(DRLCMACDL, LOGL_DEBUG, "- Sending new block at BSN %d\n",
+		m_window.v_s());
+
+#warning "Selection of the CS doesn't belong here"
+	if (cs == 0) {
+		cs = bts_data()->initial_cs_dl;
+		if (cs < 1 || cs > 4)
+			cs = 1;
+	}
+	/* total length of block, including spare bits */
+	const uint8_t block_length = gprs_rlcmac_cs[cs].block_length;
+	/* length of usable data of block, w/o spare bits, inc. MAC */
+	const uint8_t block_data_len = gprs_rlcmac_cs[cs].block_data;
+
+	/* now we still have untransmitted LLC data, so we fill mac block */
+	rlc_data = m_rlc.block(bsn);
+	data = rlc_data->prepare(block_data_len);
+
+	rh = (struct rlc_dl_header *)data;
+	rh->pt = 0; /* Data Block */
+	rh->rrbp = rh->s_p = 0; /* Polling, set later, if required */
+	rh->usf = 7; /* will be set at scheduler */
+	rh->pr = 0; /* FIXME: power reduction */
+	rh->tfi = m_tfi; /* TFI */
+	rh->fbi = 0; /* Final Block Indicator, set late, if true */
+	rh->bsn = bsn; /* Block Sequence Number */
+	rh->e = 0; /* Extension bit, maybe set later */
+	e_pointer = data + 2; /* points to E of current chunk */
+	data += sizeof(*rh);
+	delimiter = data; /* where next length header would be stored */
+	space = block_data_len - sizeof(*rh);
+	while (1) {
+		chunk = m_llc.chunk_size();
+		/* if chunk will exceed block limit */
+		if (chunk > space) {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d "
+				"larger than space (%d) left in block: copy "
+				"only remaining space, and we are done\n",
+				chunk, space);
+			/* block is filled, so there is no extension */
+			*e_pointer |= 0x01;
+			/* fill only space */
+			m_llc.consume(data, space);
+			/* return data block as message */
+			break;
+		}
+		/* if FINAL chunk would fit precisely in space left */
+		if (chunk == space && llist_empty(&m_llc.queue)) {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d "
+				"would exactly fit into space (%d): because "
+				"this is a final block, we don't add length "
+				"header, and we are done\n", chunk, space);
+			LOGP(DRLCMACDL, LOGL_INFO, "Complete DL frame for "
+				"%s that fits precisely in last block: "
+				"len=%d\n", tbf_name(this), m_llc.frame_length());
+			gprs_rlcmac_dl_bw(this, m_llc.frame_length());
+			/* block is filled, so there is no extension */
+			*e_pointer |= 0x01;
+			/* fill space */
+			m_llc.consume(data, space);
+			m_llc.reset();
+			/* final block */
+			rh->fbi = 1; /* we indicate final block */
+			set_state(GPRS_RLCMAC_FINISHED);
+			/* return data block as message */
+			break;
+		}
+		/* if chunk would fit exactly in space left */
+		if (chunk == space) {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d "
+				"would exactly fit into space (%d): add length "
+				"header with LI=0, to make frame extend to "
+				"next block, and we are done\n", chunk, space);
+			/* make space for delimiter */
+			if (delimiter != data)
+				memmove(delimiter + 1, delimiter,
+					data - delimiter);
+			data++;
+			space--;
+			/* add LI with 0 length */
+			li = (struct rlc_li_field *)delimiter;
+			li->e = 1; /* not more extension */
+			li->m = 0; /* shall be set to 0, in case of li = 0 */
+			li->li = 0; /* chunk fills the complete space */
+			// no need to set e_pointer nor increase delimiter
+			/* fill only space, which is 1 octet less than chunk */
+			m_llc.consume(data, space);
+			/* return data block as message */
+			break;
+		}
+		LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d is less "
+			"than remaining space (%d): add length header to "
+			"to delimit LLC frame\n", chunk, space);
+		/* the LLC frame chunk ends in this block */
+		/* make space for delimiter */
+		if (delimiter != data)
+			memmove(delimiter + 1, delimiter, data - delimiter);
+		data++;
+		space--;
+		/* add LI to delimit frame */
+		li = (struct rlc_li_field *)delimiter;
+		li->e = 0; /* Extension bit, maybe set later */
+		li->m = 0; /* will be set later, if there is more LLC data */
+		li->li = chunk; /* length of chunk */
+		e_pointer = delimiter; /* points to E of current delimiter */
+		delimiter++;
+		/* copy (rest of) LLC frame to space and reset later */
+		m_llc.consume(data, chunk);
+		data += chunk;
+		space -= chunk;
+		LOGP(DRLCMACDL, LOGL_INFO, "Complete DL frame for %s"
+			"len=%d\n", tbf_name(this), m_llc.frame_length());
+		gprs_rlcmac_dl_bw(this, m_llc.frame_length());
+		m_llc.reset();
+		/* dequeue next LLC frame, if any */
+		msg = llc_dequeue(gprs_bssgp_pcu_current_bctx());
+		if (msg) {
+			LOGP(DRLCMACDL, LOGL_INFO, "- Dequeue next LLC for "
+				"%s (len=%d)\n", tbf_name(this), msg->len);
+			m_llc.put_frame(msg->data, msg->len);
+			bts->llc_frame_sched();
+			msgb_free(msg);
+		}
+		/* if we have more data and we have space left */
+		if (space > 0 && m_llc.frame_length()) {
+			li->m = 1; /* we indicate more frames to follow */
+			continue;
+		}
+		/* if we don't have more LLC frames */
+		if (!m_llc.frame_length()) {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "-- Final block, so we "
+				"done.\n");
+			li->e = 1; /* we cannot extend */
+			rh->fbi = 1; /* we indicate final block */
+			first_fin_ack = true;
+				/* + 1 indicates: first final ack */
+			set_state(GPRS_RLCMAC_FINISHED);
+			break;
+		}
+		/* we have no space left */
+		LOGP(DRLCMACDL, LOGL_DEBUG, "-- No space left, so we are "
+			"done.\n");
+		li->e = 1; /* we cannot extend */
+		break;
+	}
+	LOGP(DRLCMACDL, LOGL_DEBUG, "data block: %s\n",
+		osmo_hexdump(rlc_data->block, block_length));
+#warning "move this up?"
+	rlc_data->len = block_length;
+	/* raise send state and set ack state array */
+	m_window.m_v_b.mark_unacked(bsn);
+	m_window.increment_send();
+
+	return create_dl_acked_block(fn, ts, bsn, first_fin_ack);
+}
+
+struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
+				const uint32_t fn, const uint8_t ts,
+				const int index, const bool first_fin_ack)
+{
+	uint8_t *data;
+	struct rlc_dl_header *rh;
+	struct msgb *dl_msg;
+	uint8_t len;
+
+	/* get data and header from current block */
+	data = m_rlc.block(index)->block;
+	len = m_rlc.block(index)->len;
+	rh = (struct rlc_dl_header *)data;
+
+	/* Clear Polling, if still set in history buffer */
+	rh->s_p = 0;
+		
+	/* poll after POLL_ACK_AFTER_FRAMES frames, or when final block is tx.
+	 */
+	if (m_tx_counter >= POLL_ACK_AFTER_FRAMES || first_fin_ack) {
+		if (first_fin_ack) {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- Scheduling Ack/Nack "
+				"polling, because first final block sent.\n");
+		} else {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- Scheduling Ack/Nack "
+				"polling, because %d blocks sent.\n",
+				POLL_ACK_AFTER_FRAMES);
+		}
+		/* scheduling not possible, because: */
+		if (poll_state != GPRS_RLCMAC_POLL_NONE)
+			LOGP(DRLCMACDL, LOGL_DEBUG, "Polling is already "
+				"sheduled for %s, so we must wait for "
+				"requesting downlink ack\n", tbf_name(this));
+		else if (control_ts != ts)
+			LOGP(DRLCMACDL, LOGL_DEBUG, "Polling cannot be "
+				"sheduled in this TS %d, waiting for "
+				"TS %d\n", ts, control_ts);
+#warning "What happens to the first_fin_ack in case something is already scheduled?"
+		else if (bts->sba()->find(trx->trx_no, ts, (fn + 13) % 2715648))
+			LOGP(DRLCMACDL, LOGL_DEBUG, "Polling cannot be "
+				"sheduled, because single block alllocation "
+				"already exists\n");
+		else  {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "Polling sheduled in this "
+				"TS %d\n", ts);
+			m_tx_counter = 0;
+			/* start timer whenever we send the final block */
+			if (rh->fbi == 1)
+				tbf_timer_start(this, 3191, bts_data()->t3191, 0);
+
+			/* schedule polling */
+			poll_state = GPRS_RLCMAC_POLL_SCHED;
+			poll_fn = (fn + 13) % 2715648;
+
+			/* set polling in header */
+			rh->rrbp = 0; /* N+13 */
+			rh->s_p = 1; /* Polling */
+		}
+	}
+
+	/* return data block as message */
+	dl_msg = msgb_alloc(len, "rlcmac_dl_data");
+	if (!dl_msg)
+		return NULL;
+
+	/* Increment TX-counter */
+	m_tx_counter++;
+
+	memcpy(msgb_put(dl_msg, len), data, len);
+	bts->rlc_sent();
+
+	return dl_msg;
+}
+
+int gprs_rlcmac_dl_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
+{
+	int16_t dist; /* must be signed */
+	uint16_t lost = 0, received = 0;
+	char show_rbb[65];
+	char show_v_b[RLC_MAX_SNS + 1];
+	const uint16_t mod_sns = m_window.mod_sns();
+
+	Decoding::extract_rbb(rbb, show_rbb);
+	/* show received array in debug (bit 64..1) */
+	LOGP(DRLCMACDL, LOGL_DEBUG, "- ack:  (BSN=%d)\"%s\""
+		"(BSN=%d)  R=ACK I=NACK\n", (ssn - 64) & mod_sns,
+		show_rbb, (ssn - 1) & mod_sns);
+
+	/* apply received array to receive state (SSN-64..SSN-1) */
+	/* calculate distance of ssn from V(S) */
+	dist = (m_window.v_s() - ssn) & mod_sns;
+	/* check if distance is less than distance V(A)..V(S) */
+	if (dist >= m_window.distance()) {
+		/* this might happpen, if the downlink assignment
+		 * was not received by ms and the ack refers
+		 * to previous TBF
+		 * FIXME: we should implement polling for
+		 * control ack!*/
+		LOGP(DRLCMACDL, LOGL_NOTICE, "- ack range is out of "
+			"V(A)..V(S) range %s Free TBF!\n", tbf_name(this));
+		return 1; /* indicate to free TBF */
+	}
+
+	m_window.update(bts, show_rbb, ssn,
+			&lost, &received);
+
+	/* report lost and received packets */
+	gprs_rlcmac_received_lost(this, received, lost);
+
+	/* raise V(A), if possible */
+	m_window.raise(m_window.move_window());
+
+	/* show receive state array in debug (V(A)..V(S)-1) */
+	m_window.show_state(show_v_b);
+	LOGP(DRLCMACDL, LOGL_DEBUG, "- V(B): (V(A)=%d)\"%s\""
+		"(V(S)-1=%d)  A=Acked N=Nacked U=Unacked "
+		"X=Resend-Unacked I=Invalid\n",
+		m_window.v_a(), show_v_b,
+		m_window.v_s_mod(-1));
+
+	if (state_is(GPRS_RLCMAC_FINISHED) && m_window.window_empty()) {
+		LOGP(DRLCMACDL, LOGL_NOTICE, "Received acknowledge of "
+			"all blocks, but without final ack "
+			"inidcation (don't worry)\n");
+	}
+	return 0;
+}
+
+
+int gprs_rlcmac_dl_tbf::maybe_start_new_window()
+{
+	struct msgb *msg;
+	uint16_t received;
+
+	LOGP(DRLCMACDL, LOGL_DEBUG, "- Final ACK received.\n");
+	/* range V(A)..V(S)-1 */
+	received = m_window.count_unacked();
+
+	/* report all outstanding packets as received */
+	gprs_rlcmac_received_lost(this, received, 0);
+
+	set_state(GPRS_RLCMAC_WAIT_RELEASE);
+
+	/* check for LLC PDU in the LLC Queue */
+	msg = llc_dequeue(gprs_bssgp_pcu_current_bctx());
+	if (!msg) {
+		/* no message, start T3193, change state to RELEASE */
+		LOGP(DRLCMACDL, LOGL_DEBUG, "- No new message, so we release.\n");
+		/* start T3193 */
+		tbf_timer_start(this, 3193,
+			bts_data()->t3193_msec / 1000,
+			(bts_data()->t3193_msec % 1000) * 1000);
+
+		return 0;
+	}
+
+	/* we have more data so we will re-use this tbf */
+	reuse_tbf(msg->data, msg->len);
+	msgb_free(msg);
+	return 0;
+}
+
+int gprs_rlcmac_dl_tbf::rcvd_dl_ack(uint8_t final_ack, uint8_t ssn, uint8_t *rbb)
+{
+	LOGP(DRLCMACDL, LOGL_DEBUG, "%s downlink acknowledge\n", tbf_name(this));
+
+	if (!final_ack)
+		return update_window(ssn, rbb);
+	return maybe_start_new_window();
+}
+
+void gprs_rlcmac_dl_tbf::reuse_tbf(const uint8_t *data, const uint16_t len)
+{
+	bts->tbf_reused();
+	m_llc.put_frame(data, len);
+	bts->llc_frame_sched();
+
+	/* reset rlc states */
+	m_tx_counter = 0;
+	m_wait_confirm = 0;
+	m_window.reset();
+
+	/* keep to flags */
+	state_flags &= GPRS_RLCMAC_FLAG_TO_MASK;
+	state_flags &= ~(1 << GPRS_RLCMAC_FLAG_CCCH);
+
+	update();
+
+	LOGP(DRLCMAC, LOGL_DEBUG, "%s Trigger dowlink assignment on PACCH, "
+		"because another LLC PDU has arrived in between\n",
+		tbf_name(this));
+	bts->trigger_dl_ass(this, this, NULL);
+}
+
+bool gprs_rlcmac_dl_tbf::dl_window_stalled() const
+{
+	return m_window.window_stalled();
+}
+