Changes RLC/MAC code from C++ to Cjolly/outdated_c

1 files changed, 1461 insertions, 0 deletions

diff --git a/src/gprs_rlcmac_data.c b/src/gprs_rlcmac_data.c
new file mode 100644
index 00000000..0efcb798
--- /dev/null
+++ b/src/gprs_rlcmac_data.c
@@ -0,0 +1,1461 @@
+/* Data block transfer
+ *
+ * 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 <gprs_bssgp_pcu.h>
+#include <gprs_rlcmac.h>
+#include <gprs_rlcmac_ctrl.h>
+#include <pcu_l1_if.h>
+
+extern void *tall_pcu_ctx;
+
+int bssgp_tx_llc_discarded(struct bssgp_bvc_ctx *bctx, uint32_t tlli,
+                           uint8_t num_frames, uint32_t num_octets);
+
+/* 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 10
+
+/* If acknowledgement to uplink/downlin assignmentshould be polled */
+#define POLLING_ASSIGNMENT 0
+
+/* 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));
+
+int gprs_rlcmac_poll_timeout(struct gprs_rlcmac_tbf *tbf)
+{
+	LOGP(DRLCMAC, LOGL_NOTICE, "Poll timeout for %s TBF=%d\n",
+		(tbf->direction == GPRS_RLCMAC_UL_TBF) ? "UL" : "DL", tbf->tfi);
+
+	tbf->poll_state = GPRS_RLCMAC_POLL_NONE;
+
+	if (tbf->ul_ack_state == GPRS_RLCMAC_UL_ACK_WAIT_ACK) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "- Timeout for polling PACKET "
+			"CONTROL ACK for PACKET UPLINK ACK\n");
+		tbf->ul_ack_state = GPRS_RLCMAC_UL_ACK_NONE;
+		if (tbf->state == GPRS_RLCMAC_FINISHED) {
+			struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+
+			tbf->dir.ul.n3103++;
+			if (tbf->dir.ul.n3103 == bts->n3103) {
+				LOGP(DRLCMAC, LOGL_NOTICE,
+					"- N3103 exceeded\n");
+				tbf_new_state(tbf, GPRS_RLCMAC_RELEASING);
+				tbf_timer_start(tbf, 3169, bts->t3169, 0);
+				return 0;
+			}
+			/* reschedule UL ack */
+			tbf->ul_ack_state = GPRS_RLCMAC_UL_ACK_SEND_ACK;
+		}
+	} else
+	if (tbf->ul_ass_state == GPRS_RLCMAC_UL_ASS_WAIT_ACK) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "- Timeout for polling PACKET "
+			"CONTROL ACK for PACKET UPLINK ASSIGNMENT.\n");
+		tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_NONE;
+	} else
+	if (tbf->dl_ass_state == GPRS_RLCMAC_DL_ASS_WAIT_ACK) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "- Timeout for polling PACKET "
+			"CONTROL ACK for PACKET DOWNLINK ASSIGNMENT.\n");
+		tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_NONE;
+		/* in case out downlink assigment failed: */
+		if (tbf->state == GPRS_RLCMAC_ASSIGN) {
+			LOGP(DRLCMAC, LOGL_NOTICE, "- Assignment failed\n");
+			tbf_free(tbf);
+		}
+	} else
+	if (tbf->direction == GPRS_RLCMAC_DL_TBF)
+	{
+		struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+
+		LOGP(DRLCMAC, LOGL_NOTICE, "- Timeout for polling PACKET "
+			" DOWNLINK ACK.\n");
+		tbf->dir.dl.n3105++;
+		if (tbf->dir.dl.n3105 == bts->n3105) {
+			LOGP(DRLCMAC, LOGL_NOTICE, "- N3105 exceeded\n");
+			tbf_new_state(tbf, GPRS_RLCMAC_RELEASING);
+			tbf_timer_start(tbf, 3195, bts->t3195, 0);
+			return 0;
+		}
+	} else
+		LOGP(DRLCMAC, LOGL_ERROR, "- Poll Timeout, but no event!\n");
+
+	return 0;
+}
+
+int gprs_rlcmac_rcv_control_ack(uint8_t trx, uint8_t ts, uint32_t fn,
+	uint32_t tlli)
+{
+	struct gprs_rlcmac_tbf *tbf;
+	uint8_t tfi;
+
+	tbf = tbf_by_poll_fn(fn, trx, ts);
+	if (!tbf) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "PACKET CONTROL ACK with "
+			"unknown FN=%u TLL=0x%08x (TRX %d TS %d)\n",
+			fn, tlli, trx, ts);
+		return -EINVAL;
+	}
+	tfi = tbf->tfi;
+	if (tlli != tbf->tlli) {
+		LOGP(DRLCMAC, LOGL_INFO, "Phone changed TLLI to "
+			"0x%08x\n", tlli);
+		tbf->tlli = tlli;
+	}
+	LOGP(DRLCMAC, LOGL_DEBUG, "RX: [PCU <- BTS] TFI: %u TLLI: 0x%08x Packet Control Ack\n", tbf->tfi, tbf->tlli);
+	tbf->poll_state = GPRS_RLCMAC_POLL_NONE;
+
+	/* check if this control ack belongs to packet uplink ack */
+	if (tbf->ul_ack_state == GPRS_RLCMAC_UL_ACK_WAIT_ACK) {
+		LOGP(DRLCMAC, LOGL_DEBUG, "TBF: [UPLINK] END TFI: %u TLLI: 0x%08x \n", tbf->tfi, tbf->tlli);
+		tbf->ul_ack_state = GPRS_RLCMAC_UL_ACK_NONE;
+		tbf_free(tbf);
+		return 0;
+	}
+	if (tbf->dl_ass_state == GPRS_RLCMAC_DL_ASS_WAIT_ACK) {
+		LOGP(DRLCMAC, LOGL_DEBUG, "TBF: [UPLINK] DOWNLINK ASSIGNED TFI: %u TLLI: 0x%08x \n", tbf->tfi, tbf->tlli);
+		tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_NONE;
+		if (tbf->direction == GPRS_RLCMAC_UL_TBF)
+			tbf = tbf_by_tlli(tbf->tlli,
+						GPRS_RLCMAC_DL_TBF);
+		if (!tbf) {
+			LOGP(DRLCMAC, LOGL_ERROR, "Got ACK, but DL "
+				"TBF is gone\n");
+			return -EIO;
+		}
+		tbf_new_state(tbf, GPRS_RLCMAC_FLOW);
+		tbf_assign_control_ts(tbf);
+		return 0;
+	}
+	if (tbf->ul_ass_state == GPRS_RLCMAC_UL_ASS_WAIT_ACK) {
+		LOGP(DRLCMAC, LOGL_DEBUG, "TBF: [DOWNLINK] UPLINK ASSIGNED TFI: %u TLLI: 0x%08x \n", tbf->tfi, tbf->tlli);
+		tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_NONE;
+		if (tbf->direction == GPRS_RLCMAC_DL_TBF)
+			tbf = tbf_by_tlli(tbf->tlli,
+						GPRS_RLCMAC_UL_TBF);
+		if (!tbf) {
+			LOGP(DRLCMAC, LOGL_ERROR, "Got ACK, but UL "
+				"TBF is gone\n");
+			return -EIO;
+		}
+		tbf_new_state(tbf, GPRS_RLCMAC_FLOW);
+		tbf_assign_control_ts(tbf);
+		return 0;
+	}
+	LOGP(DRLCMAC, LOGL_ERROR, "Error: received PACET CONTROL ACK "
+		"at no request\n");
+	return EINVAL;
+}
+
+int gprs_rlcmac_rcv_downlink_ack(uint8_t trx, uint8_t ts, uint32_t fn, uint16_t tfi, uint8_t final, uint8_t ssn, uint8_t *rbb, uint8_t request)
+{
+	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+	struct gprs_rlcmac_tbf *tbf;
+	int rc;
+
+	tbf = tbf_by_poll_fn(fn, trx, ts);
+	if (!tbf) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "PACKET DOWNLINK ACK with "
+			"unknown FN=%u TBF=%d (TRX %d TS %d)\n",
+			fn, tfi, trx, ts);
+		return -EINVAL;
+	}
+	/* reset N3105 */
+	tbf->dir.dl.n3105 = 0;
+	/* stop timer T3191 */
+	tbf_timer_stop(tbf);
+	LOGP(DRLCMAC, LOGL_DEBUG, "RX: [PCU <- BTS] TFI: %u TLLI: 0x%08x Packet Downlink Ack/Nack\n", tbf->tfi, tbf->tlli);
+	tbf->poll_state = GPRS_RLCMAC_POLL_NONE;
+
+	rc = gprs_rlcmac_downlink_ack(tbf, final, ssn, rbb);
+	if (rc == 1) {
+		tbf_free(tbf);
+		return 0;
+	}
+	/* check for channel request */
+	if (request) {
+		uint8_t trx, ts;
+		struct gprs_rlcmac_tbf *ul_tbf;
+
+		LOGP(DRLCMAC, LOGL_DEBUG, "MS requests UL TBF in ack "
+			"message, so we provide one:\n");
+		/* create new TBF, use sme TRX as DL TBF */
+		tfi = tfi_alloc(GPRS_RLCMAC_UL_TBF, &trx, &ts, tbf->trx, tbf->first_ts);
+		if (tfi < 0) {
+			LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH ressource\n");
+			/* FIXME: send reject */
+			return -EIO;
+		}
+		/* use multislot class of downlink TBF */
+		ul_tbf = tbf_alloc(tbf, GPRS_RLCMAC_UL_TBF, tfi, trx,
+			ts, tbf->ms_class, 0);
+		if (!ul_tbf) {
+			LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH ressource\n");
+			/* FIXME: send reject */
+			return -EIO;
+		}
+		ul_tbf->tlli = tbf->tlli;
+		ul_tbf->tlli_valid = 1; /* no contention resolution */
+		ul_tbf->dir.ul.contention_resolution_done = 1;
+		ul_tbf->ta = tbf->ta; /* use current TA */
+		tbf_new_state(ul_tbf, GPRS_RLCMAC_ASSIGN);
+		tbf_timer_start(ul_tbf, 3169, bts->t3169, 0);
+		/* schedule uplink assignment */
+		tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_SEND_ASS;
+	}
+
+	return 0;
+}
+
+#ifdef DEBUG_DL_ASS_IDLE
+	char debug_imsi[16];
+#endif
+
+void tbf_timer_cb(void *_tbf)
+{
+	struct gprs_rlcmac_tbf *tbf = (struct gprs_rlcmac_tbf *)_tbf;
+
+	LOGP(DRLCMAC, LOGL_DEBUG, "%s TBF=%d timer %u expired.\n",
+		(tbf->direction == GPRS_RLCMAC_UL_TBF) ? "UL" : "DL", tbf->tfi,
+		tbf->T);
+
+	tbf->num_T_exp++;
+
+	switch (tbf->T) {
+#ifdef DEBUG_DL_ASS_IDLE
+	case 1234:
+		gprs_rlcmac_trigger_downlink_assignment(tbf, NULL, debug_imsi);
+		break;
+#endif
+	case 0: /* assignment */
+		/* change state to FLOW, so scheduler will start transmission */
+		if (tbf->state == GPRS_RLCMAC_ASSIGN) {
+			tbf_new_state(tbf, GPRS_RLCMAC_FLOW);
+			tbf_assign_control_ts(tbf);
+		} else
+			LOGP(DRLCMAC, LOGL_ERROR, "Error: TBF is not in assign "
+				"state\n");
+		break;
+	case 3169:
+	case 3191:
+	case 3195:
+		LOGP(DRLCMAC, LOGL_NOTICE, "TBF T%d timeout during "
+			"transsmission\n", tbf->T);
+		/* fall through */
+	case 3193:
+		LOGP(DRLCMAC, LOGL_DEBUG, "TBF will be freed due to timeout\n");
+		/* free TBF */
+		tbf_free(tbf);
+		break;
+	default:
+		LOGP(DRLCMAC, LOGL_ERROR, "Timer expired in unknown mode: %u\n",
+			tbf->T);
+	}
+}
+
+/*
+ * 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;
+
+	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;
+	}
+	*tlli = ntohl(*((uint32_t *)data));
+
+	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)
+{
+	int final = (tbf->state == GPRS_RLCMAC_FINISHED);
+	struct msgb *msg;
+
+	if (final && tbf->poll_state != GPRS_RLCMAC_POLL_NONE) {
+		LOGP(DRLCMACUL, LOGL_DEBUG, "Polling is already "
+			"sheduled for TBF=%d, so we must wait for final uplink "
+			"ack...\n", tbf->tfi);
+			return NULL;
+	}
+
+	msg = write_packet_uplink_ack(tbf, final);
+	if (!msg)
+		return NULL;
+
+	/* now we must set this flag, so we are allowed to assign downlink
+	 * TBF on PACCH. it is only allowed when TLLI is aknowledged. */
+	tbf->dir.ul.contention_resolution_done = 1;
+
+	if (final) {
+		tbf->poll_state = GPRS_RLCMAC_POLL_SCHED;
+		tbf->poll_fn = (fn + 13) % 2715648;
+		/* waiting for final acknowledge */
+		tbf->ul_ack_state = GPRS_RLCMAC_UL_ACK_WAIT_ACK;
+		tbf->dir.ul.final_ack_sent = 1;
+	} else
+		tbf->ul_ack_state = GPRS_RLCMAC_UL_ACK_NONE;
+
+	return msg;
+}
+
+/* receive UL data block
+ *
+ * The blocks are defragmented and forwarded as LLC frames, if complete.
+ */
+int gprs_rlcmac_rcv_data_block_acknowledged(uint8_t trx, uint8_t ts,
+	uint8_t *data, uint8_t len)
+{
+	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+	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(rh->tfi, trx, ts, GPRS_RLCMAC_UL_TBF);
+	if (!tbf) {
+		LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA unknown TBF=%d\n",
+			rh->tfi);
+		return 0;
+	}
+
+	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);
+
+	/* get TLLI */
+	if (!tbf->tlli_valid) {
+		struct gprs_rlcmac_tbf *dl_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;
+		}
+		tbf->tlli_valid = 1;
+		LOGP(DRLCMACUL, LOGL_INFO, "Decoded premier TLLI=0x%08x of "
+			"UL DATA TBF=%d.\n", tbf->tlli, rh->tfi);
+		if ((dl_tbf = 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);
+		}
+	/* 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 == 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 == 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 == 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) {
+			/* 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)
+{
+	struct msgb *msg;
+	struct gprs_rlcmac_tbf *new_tbf;
+
+#if POLLING_ASSIGNMENT == 1
+	if (tbf->poll_state != GPRS_RLCMAC_POLL_NONE) {
+		LOGP(DRLCMACUL, LOGL_DEBUG, "Polling is already "
+			"sheduled for TBF=%d, so we must wait for uplink "
+			"assignment...\n", tbf->tfi);
+			return NULL;
+	}
+#endif
+
+	/* on down TBF we get the uplink TBF to be assigned. */
+	if (tbf->direction == GPRS_RLCMAC_DL_TBF)
+		new_tbf = tbf_by_tlli(tbf->tlli, GPRS_RLCMAC_UL_TBF);
+	else
+		new_tbf = tbf;
+		
+	if (!new_tbf) {
+		LOGP(DRLCMACUL, LOGL_ERROR, "We have a schedule for uplink "
+			"assignment at downlink TBF=%d, but there is no uplink "
+			"TBF\n", tbf->tfi);
+		tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_NONE;
+		return NULL;
+	}
+
+	LOGP(DRLCMAC, LOGL_INFO, "TBF: START TFI: %u TLLI: 0x%08x Packet Uplink Assignment (PACCH)\n", new_tbf->tfi, new_tbf->tlli);
+
+	msg = write_packet_uplink_assignment(tbf->tfi,
+		(tbf->direction == GPRS_RLCMAC_DL_TBF), 0, 0, new_tbf,
+		POLLING_ASSIGNMENT);
+	if (!msg)
+		return NULL;
+
+#if POLLING_ASSIGNMENT == 1
+	FIXME process does not work, also the acknowledgement is not checked.
+	tbf->poll_state = GPRS_RLCMAC_POLL_SCHED;
+	tbf->poll_fn = (fn + 13) % 2715648;
+	tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_WAIT_ACK;
+#else
+	tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_NONE;
+	tbf_new_state(new_tbf, GPRS_RLCMAC_FLOW);
+	tbf_assign_control_ts(new_tbf);
+#endif
+
+	return msg;
+}
+
+int gprs_rlcmac_rcv_rach(uint8_t ra, uint32_t Fn, int16_t qta)
+{
+	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+	struct gprs_rlcmac_tbf *tbf;
+	uint8_t trx, ts;
+	int8_t tfi; /* must be signed */
+	uint8_t imm_ass[23];
+	int rc;
+
+	LOGP(DRLCMAC, LOGL_DEBUG, "MS requests UL TBF on RACH, so we provide "
+		"one:\n");
+	// Create new TBF
+	tfi = tfi_alloc(GPRS_RLCMAC_UL_TBF, &trx, &ts, -1, -1);
+	if (tfi < 0) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH ressource\n");
+		/* FIXME: send reject */
+		return -EBUSY;
+	}
+	/* set class to 0, since we don't know the multislot class yet */
+	tbf = tbf_alloc(NULL, GPRS_RLCMAC_UL_TBF, tfi, trx, ts, 0, 1);
+	if (!tbf) {
+		LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH ressource\n");
+		/* FIXME: send reject */
+		return -EBUSY;
+	}
+	if (qta < 0)
+		qta = 0;
+	if (qta > 252)
+		qta = 252;
+	tbf->ta = qta >> 2;
+	tbf_new_state(tbf, GPRS_RLCMAC_FLOW);
+	tbf_timer_start(tbf, 3169, bts->t3169, 0);
+	LOGP(DRLCMAC, LOGL_DEBUG, "TBF: [UPLINK] START TFI: %u\n", tbf->tfi);
+	LOGP(DRLCMAC, LOGL_DEBUG, "RX: [PCU <- BTS] TFI: %u RACH qbit-ta=%d ra=%d, Fn=%d (%d,%d,%d)\n", tbf->tfi, qta, ra, Fn, (Fn / (26 * 51)) % 32, Fn % 51, Fn % 26);
+	LOGP(DRLCMAC, LOGL_INFO, "TX: START TFI: %u Immediate Assignment Uplink (AGCH)\n", tbf->tfi);
+	rc = write_immediate_assignment_uplink(imm_ass, ra, Fn, tbf->ta, tbf->arfcn, tbf->first_ts, tbf->tsc, tbf->tfi, tbf->dir.ul.usf[tbf->first_ts], 0, 0);
+	if (rc < 0)
+		return rc;
+
+	pcu_l1if_tx_agch(imm_ass);
+	return 0;
+}
+
+
+/*
+ * DL data block flow
+ */
+
+static struct msgb *llc_dequeue(struct gprs_rlcmac_tbf *tbf)
+{
+	struct msgb *msg;
+	struct timeval *tv, tv_now;
+	uint32_t octets = 0, frames = 0;
+
+	gettimeofday(&tv_now, NULL);
+
+	while ((msg = msgb_dequeue(&tbf->llc_queue))) {
+		tv = (struct timeval *)msg->data;
+		msgb_pull(msg, sizeof(*tv));
+		if (tv->tv_sec /* not infinite */
+		 && (tv_now.tv_sec > tv->tv_sec /* and secs expired */
+		  || (tv_now.tv_sec == tv->tv_sec /* .. or if secs equal .. */
+		   && tv_now.tv_usec > tv->tv_usec))) { /* .. usecs expired */
+			LOGP(DRLCMACDL, LOGL_NOTICE, "Discarding LLC PDU of "
+				"DL TBF=%d, because lifetime limit reached\n",
+				tbf->tfi);
+			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, tbf->tlli, frames, octets);
+	}
+
+	return msg;
+}
+
+static int gprs_rlcmac_debug_bw(struct gprs_rlcmac_tbf *tbf, uint16_t octets)
+{
+	struct timeval now_tv, *bw_tv = &tbf->bw_tv;
+	uint32_t elapsed;
+
+	tbf->bw_octets += octets;
+
+	gettimeofday(&now_tv, NULL);
+	elapsed = ((now_tv.tv_sec - bw_tv->tv_sec) << 7)
+		+ ((now_tv.tv_usec - bw_tv->tv_usec) << 7) / 1000000;
+	if (elapsed < 128)
+		return 0;
+
+	LOGP(DRLCMACBW, LOGL_DEBUG, "DL Bandwitdh of TLLI=0x%08x: %d KBits/s\n",
+		tbf->tlli, tbf->bw_octets / elapsed);
+
+	/* reset bandwidth values timestamp */
+	memcpy(bw_tv, &now_tv, sizeof(struct timeval));
+	tbf->bw_octets = 0;
+
+	return 0;
+}
+
+/* send DL data block
+ *
+ * The messages are fragmented and forwarded as data blocks.
+ */
+struct msgb *gprs_rlcmac_send_data_block_acknowledged(
+	struct gprs_rlcmac_tbf *tbf, uint32_t fn, uint8_t ts)
+{
+	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+	struct rlc_dl_header *rh;
+	struct rlc_li_field *li;
+	uint8_t block_length; /* total length of block, including spare bits */
+	uint8_t block_data; /* usable data of block, w/o spare bits, inc. MAC */
+	struct msgb *msg, *dl_msg;
+	uint8_t bsn;
+	uint16_t mod_sns = tbf->sns - 1;
+	uint16_t mod_sns_half = (tbf->sns >> 1) - 1;
+	uint16_t index;
+	uint8_t *delimiter, *data, *e_pointer;
+	uint8_t len;
+	uint16_t space, chunk;
+
+	LOGP(DRLCMACDL, LOGL_DEBUG, "DL DATA TBF=%d downlink (V(A)==%d .. "
+		"V(S)==%d)\n", tbf->tfi, tbf->dir.dl.v_a, tbf->dir.dl.v_s);
+
+do_resend:
+	/* check if there is a block with negative acknowledgement */
+	for (bsn = tbf->dir.dl.v_a; bsn != tbf->dir.dl.v_s; 
+	     bsn = (bsn + 1) & mod_sns) {
+		index = (bsn & mod_sns_half);
+		if (tbf->dir.dl.v_b[index] == 'N'
+		 || tbf->dir.dl.v_b[index] == 'X') {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- Resending BSN %d\n",
+				bsn);
+			/* re-send block with negative aknowlegement */
+			tbf->dir.dl.v_b[index] = 'U'; /* unacked */
+			goto tx_block;
+		}
+	}
+
+	/* if the window has stalled, or transfer is complete,
+	 * send an unacknowledged block */
+	if (tbf->state == GPRS_RLCMAC_FINISHED
+	 || ((tbf->dir.dl.v_s - tbf->dir.dl.v_a) & mod_sns) == tbf->ws) {
+	 	int resend = 0;
+
+		if (tbf->state == GPRS_RLCMAC_FINISHED)
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- Restarting at BSN %d, "
+				"because all blocks have been transmitted.\n",
+					tbf->dir.dl.v_a);
+		else
+			LOGP(DRLCMACDL, LOGL_NOTICE, "- Restarting at BSN %d, "
+				"because all window is stalled.\n",
+					tbf->dir.dl.v_a);
+		/* 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 (tbf->dir.dl.v_s == tbf->dir.dl.v_a) {
+			LOGP(DRLCMACDL, LOGL_ERROR, "- MS acked all block, "
+				"but we still transmitting!\n");
+			/* we just send final block again */
+			index = ((tbf->dir.dl.v_s - 1) & mod_sns_half);
+			goto tx_block;
+		}
+		
+		/* cycle through all unacked blocks */
+		for (bsn = tbf->dir.dl.v_a; bsn != tbf->dir.dl.v_s;
+		     bsn = (bsn + 1) & mod_sns) {
+			index = (bsn & mod_sns_half);
+			if (tbf->dir.dl.v_b[index] == 'U') {
+				/* mark to be re-send */
+				tbf->dir.dl.v_b[index] = 'X';
+				resend++;
+			}
+		}
+		/* At this point there should be at leasst 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 */
+			index = ((tbf->dir.dl.v_s - 1) & mod_sns_half);
+			goto tx_block;
+		}
+		goto do_resend;
+	}
+
+	LOGP(DRLCMACDL, LOGL_DEBUG, "- Sending new block at BSN %d\n",
+		tbf->dir.dl.v_s);
+
+	/* now we still have untransmitted LLC data, so we fill mac block */
+	index = tbf->dir.dl.v_s & mod_sns_half;
+	data = tbf->rlc_block[index];
+	switch (bts->initial_cs) {
+	case 2: /* CS-2 */
+		block_length = 34;
+		block_data = 33;
+		break;
+	case 3: /* CS-3 */
+		block_length = 40;
+		block_data = 39;
+		break;
+	case 4: /* CS-4 */
+		block_length = 54;
+		block_data = 53;
+		break;
+	default: /* CS-1 */
+		block_length = 23;
+		block_data = 23;
+	}
+	memset(data, 0x2b, block_data); /* spare bits will be left 0 */
+	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 = tbf->tfi; /* TFI */
+	rh->fbi = 0; /* Final Block Indicator, set late, if true */
+	rh->bsn = tbf->dir.dl.v_s; /* Block Sequence Number */
+	rh->e = 0; /* Extension bit, maybe set later */
+	e_pointer = data + 2; /* points to E of current chunk */
+	data += 3;
+	delimiter = data; /* where next length header would be stored */
+	space = block_data - 3;
+	while (1) {
+		chunk = tbf->llc_length - tbf->llc_index;
+		/* 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 */
+			memcpy(data, tbf->llc_frame + tbf->llc_index, space);
+			/* incement index */
+			tbf->llc_index += space;
+			/* return data block as message */
+			break;
+		}
+		/* if FINAL chunk would fit precisely in space left */
+		if (chunk == space && llist_empty(&tbf->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 "
+				"TBF=%d that fits precisely in last block: "
+				"len=%d\n", tbf->tfi, tbf->llc_length);
+			gprs_rlcmac_debug_bw(tbf, tbf->llc_length);
+			/* block is filled, so there is no extension */
+			*e_pointer |= 0x01;
+			/* fill space */
+			memcpy(data, tbf->llc_frame + tbf->llc_index, space);
+			/* reset LLC frame */
+			tbf->llc_index = tbf->llc_length = 0;
+			/* final block */
+			rh->fbi = 1; /* we indicate final block */
+			tbf_new_state(tbf, 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)
+				memcpy(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 */
+			memcpy(data, tbf->llc_frame + tbf->llc_index, space);
+			/* incement index */
+			tbf->llc_index += 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)
+			memcpy(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 */
+		memcpy(data, tbf->llc_frame + tbf->llc_index, chunk);
+		data += chunk;
+		space -= chunk;
+		LOGP(DRLCMACDL, LOGL_INFO, "Complete DL frame for TBF=%d: "
+			"len=%d\n", tbf->tfi, tbf->llc_length);
+		gprs_rlcmac_debug_bw(tbf, tbf->llc_length);
+		/* reset LLC frame */
+		tbf->llc_index = tbf->llc_length = 0;
+		/* dequeue next LLC frame, if any */
+		msg = llc_dequeue(tbf);
+		if (msg) {
+			LOGP(DRLCMACDL, LOGL_INFO, "- Dequeue next LLC for "
+				"TBF=%d (len=%d)\n", tbf->tfi, msg->len);
+			memcpy(tbf->llc_frame, msg->data, msg->len);
+			tbf->llc_length = msg->len;
+			msgb_free(msg);
+		}
+		/* if we have more data and we have space left */
+		if (space > 0 && tbf->llc_length) {
+			li->m = 1; /* we indicate more frames to follow */
+			continue;
+		}
+		/* if we don't have more LLC frames */
+		if (!tbf->llc_length) {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "-- Final block, so we "
+				"done.\n");
+			li->e = 1; /* we cannot extend */
+			rh->fbi = 1; /* we indicate final block */
+			tbf->dir.dl.tx_counter = POLL_ACK_AFTER_FRAMES + 1;
+				/* + 1 indicates: first final ack */
+			tbf_new_state(tbf, 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(tbf->rlc_block[index], block_length));
+	tbf->rlc_block_len[index] = block_length;
+	/* raise send state and set ack state array */
+	tbf->dir.dl.v_b[index] = 'U'; /* unacked */
+	tbf->dir.dl.v_s = (tbf->dir.dl.v_s + 1) & mod_sns; /* inc send state */
+
+tx_block:
+	/* from this point on, new block is sent or old block is resent */
+
+	/* get data and header from current block */
+	data = tbf->rlc_block[index];
+	len = tbf->rlc_block_len[index];
+	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 (tbf->dir.dl.tx_counter >= POLL_ACK_AFTER_FRAMES) {
+		if (tbf->dir.dl.tx_counter > POLL_ACK_AFTER_FRAMES) {
+			/* if rx_counter is POLL_ACK_AFTER_FRAMES + 1, this
+			 * indicates: poll caused by final ack. */
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- Scheduling Ack/Nack "
+				"polling, because final block sent.\n");
+		} else {
+			LOGP(DRLCMACDL, LOGL_DEBUG, "- Scheduling Ack/Nack "
+				"polling, because %d blocks sent.\n",
+				POLL_ACK_AFTER_FRAMES);
+		}
+		tbf->dir.dl.tx_counter = 0;
+		/* scheduling not possible, because: */
+		if (tbf->poll_state != GPRS_RLCMAC_POLL_NONE)
+			LOGP(DRLCMAC, LOGL_DEBUG, "Polling is already "
+				"sheduled for TBF=%d, so we must wait for "
+				"requesting downlink ack\n", tbf->tfi);
+		else if (tbf->control_ts != ts)
+			LOGP(DRLCMAC, LOGL_DEBUG, "Polling cannot be "
+				"sheduled in this TS %d, waiting for "
+				"TS %d\n", ts, tbf->control_ts);
+		else  {
+			LOGP(DRLCMAC, LOGL_DEBUG, "Polling sheduled in this "
+				"TS %d\n", ts);
+			/* start timer whenever we send the final block */
+			if (rh->fbi == 1)
+				tbf_timer_start(tbf, 3191, bts->t3191, 0);
+
+			/* schedule polling */
+			tbf->poll_state = GPRS_RLCMAC_POLL_SCHED;
+			tbf->poll_fn = (fn + 13) % 2715648;
+
+			/* set polling in header */
+			rh->rrbp = 0; /* N+13 */
+			rh->s_p = 1; /* Polling */
+
+			/* Increment TX-counter */
+			tbf->dir.dl.tx_counter++;
+		}
+	} else {
+		/* Increment TX-counter */
+		tbf->dir.dl.tx_counter++;
+	}
+
+	/* return data block as message */
+	dl_msg = msgb_alloc(len, "rlcmac_dl_data");
+	if (!dl_msg)
+		return NULL;
+	memcpy(msgb_put(dl_msg, len), data, len);
+
+	return dl_msg;
+}
+
+int gprs_rlcmac_downlink_ack(struct gprs_rlcmac_tbf *tbf, uint8_t final,
+	uint8_t ssn, uint8_t *rbb)
+{
+	char show_rbb[65], show_v_b[RLC_MAX_SNS + 1];
+	uint16_t mod_sns = tbf->sns - 1;
+	uint16_t mod_sns_half = (tbf->sns >> 1) - 1;
+	int i; /* must be signed */
+	int16_t dist; /* must be signed */
+	uint8_t bit;
+	uint16_t bsn;
+	struct msgb *msg;
+
+	LOGP(DRLCMACDL, LOGL_DEBUG, "TBF=%d downlink acknowledge\n",
+		tbf->tfi);
+
+	if (!final) {
+		/* show received array in debug (bit 64..1) */
+		for (i = 63; i >= 0; i--) {
+			bit = (rbb[i >> 3]  >>  (7 - (i&7)))   & 1;
+			show_rbb[i] = (bit) ? '1' : 'o';
+		}
+		show_rbb[64] = '\0';
+		LOGP(DRLCMACDL, LOGL_DEBUG, "- ack:  (BSN=%d)\"%s\""
+			"(BSN=%d)  1=ACK o=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 = (tbf->dir.dl.v_s - ssn) & mod_sns;
+		/* check if distance is less than distance V(A)..V(S) */
+		if (dist < ((tbf->dir.dl.v_s - tbf->dir.dl.v_a) & mod_sns)) {
+			/* SSN - 1 is in range V(A)..V(S)-1 */
+			for (i = 63, bsn = (ssn - 1) & mod_sns;
+			     i >= 0 && bsn != ((tbf->dir.dl.v_a - 1) & mod_sns);
+			     i--, bsn = (bsn - 1) & mod_sns) {
+				bit = (rbb[i >> 3]  >>  (7 - (i&7)))   & 1;
+				if (bit) {
+					LOGP(DRLCMACDL, LOGL_DEBUG, "- got "
+						"ack for BSN=%d\n", bsn);
+					tbf->dir.dl.v_b[bsn & mod_sns_half]
+						= 'A';
+				} else {
+					LOGP(DRLCMACDL, LOGL_DEBUG, "- got "
+						"NACK for BSN=%d\n", bsn);
+					tbf->dir.dl.v_b[bsn & mod_sns_half]
+						= 'N';
+				}
+			}
+		} else {
+			/* 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 (DL TBF=%d) Free TFB!\n",
+				tbf->tfi);
+				return 1; /* indicate to free TBF */
+		}
+
+		/* raise V(A), if possible */
+		for (i = 0, bsn = tbf->dir.dl.v_a; bsn != tbf->dir.dl.v_s;
+		     i++, bsn = (bsn + 1) & mod_sns) {
+			if (tbf->dir.dl.v_b[bsn & mod_sns_half] == 'A') {
+				tbf->dir.dl.v_b[bsn & mod_sns_half] = 'I';
+					/* mark invalid */
+				tbf->dir.dl.v_a = (tbf->dir.dl.v_a + 1)
+								& mod_sns;
+			} else
+				break;
+		}
+
+		/* show receive state array in debug (V(A)..V(S)-1) */
+		for (i = 0, bsn = tbf->dir.dl.v_a; bsn != tbf->dir.dl.v_s;
+		     i++, bsn = (bsn + 1) & mod_sns) {
+			show_v_b[i] = tbf->dir.dl.v_b[bsn & mod_sns_half];
+			if (show_v_b[i] == 0)
+				show_v_b[i] = ' ';
+		}
+		show_v_b[i] = '\0';
+		LOGP(DRLCMACDL, LOGL_DEBUG, "- V(B): (V(A)=%d)\"%s\""
+			"(V(S)-1=%d)  A=Acked N=Nacked U=Unacked "
+			"X=Resend-Unacked\n", tbf->dir.dl.v_a, show_v_b,
+			(tbf->dir.dl.v_s - 1) & mod_sns);
+
+		if (tbf->state == GPRS_RLCMAC_FINISHED
+		 && tbf->dir.dl.v_s == tbf->dir.dl.v_a) {
+			LOGP(DRLCMACDL, LOGL_NOTICE, "Received final block, "
+				"but without final ack inidcation\n");
+		} else
+			return 0;
+	} else
+		LOGP(DRLCMACDL, LOGL_DEBUG, "- Final ACK received.\n");
+
+	/* check for LLC PDU in the LLC Queue */
+	msg = llc_dequeue(tbf);
+	if (!msg) {
+		struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
+
+		/* no message, start T3193, change state to RELEASE */
+		LOGP(DRLCMACDL, LOGL_DEBUG, "- No new message, so we "
+			"release.\n");
+		/* start T3193 */
+		tbf_timer_start(tbf, 3193, bts->t3193_msec / 1000,
+			bts->t3193_msec & 1000);
+		tbf_new_state(tbf, GPRS_RLCMAC_WAIT_RELEASE);
+
+		return 0;
+	}
+	memcpy(tbf->llc_frame, msg->data, msg->len);
+	tbf->llc_length = msg->len;
+	msgb_free(msg);
+
+	/* we have a message, so we trigger downlink assignment, and there
+	 * set the state to ASSIGN. also we set old_downlink, because we
+	 * re-use this tbf. */
+	LOGP(DRLCMAC, LOGL_DEBUG, "Trigger dowlink assignment on PACCH, "
+		"because another LLC PDU has arrived in between\n");
+	memset(&tbf->dir.dl, 0, sizeof(tbf->dir.dl)); /* reset RLC states */
+	tbf_update(tbf);
+	gprs_rlcmac_trigger_downlink_assignment(tbf, tbf, NULL);
+
+	return 0;
+}
+
+
+struct msgb *gprs_rlcmac_send_packet_downlink_assignment(
+	struct gprs_rlcmac_tbf *tbf, uint32_t fn)
+{
+	struct msgb *msg;
+	struct gprs_rlcmac_tbf *new_tbf;
+
+#if POLLING_ASSIGNMENT == 1
+	if (tbf->poll_state != GPRS_RLCMAC_POLL_NONE) {
+		LOGP(DRLCMAC, LOGL_DEBUG, "Polling is already "
+			"sheduled for TBF=%d, so we must wait for downlink "
+			"assignment...\n", tbf->tfi);
+			return NULL;
+	}
+#endif
+
+	/* on uplink TBF we get the downlink TBF to be assigned. */
+	if (tbf->direction == GPRS_RLCMAC_UL_TBF) {
+		/* be sure to check first, if contention resolution is done,
+		 * otherwise we cannot send the assignment yet */
+		if (!tbf->dir.ul.contention_resolution_done) {
+			LOGP(DRLCMAC, LOGL_DEBUG, "Cannot assign DL TBF now, "
+				"because contention resolution is not "
+				"finished.\n");
+			return NULL;
+		}
+		new_tbf = tbf_by_tlli(tbf->tlli, GPRS_RLCMAC_DL_TBF);
+	} else
+		new_tbf = tbf;
+	if (!new_tbf) {
+		LOGP(DRLCMACDL, LOGL_ERROR, "We have a schedule for downlink "
+			"assignment at uplink TBF=%d, but there is no downlink "
+			"TBF\n", tbf->tfi);
+		tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_NONE;
+		return NULL;
+	}
+
+	LOGP(DRLCMAC, LOGL_INFO, "TBF: START TFI: %u TLLI: 0x%08x Packet Downlink Assignment (PACCH)\n", new_tbf->tfi, new_tbf->tlli);
+	msg = write_packet_downlink_assignment(tbf->tfi,
+		(tbf->direction == GPRS_RLCMAC_DL_TBF), new_tbf,
+		POLLING_ASSIGNMENT);
+	if (!msg)
+		return NULL;
+
+#if POLLING_ASSIGNMENT == 1
+	tbf->poll_state = GPRS_RLCMAC_POLL_SCHED;
+	tbf->poll_fn = (fn + 13) % 2715648;
+	tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_WAIT_ACK;
+#else
+	tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_NONE;
+	tbf_new_state(new_tbf, GPRS_RLCMAC_FLOW);
+	tbf_assign_control_ts(new_tbf);
+#endif
+
+	return msg;
+}
+
+static void gprs_rlcmac_downlink_assignment(struct gprs_rlcmac_tbf *tbf,
+	uint8_t poll, char *imsi)
+{
+	uint8_t imm_ass[23];
+	int rc;
+
+	LOGP(DRLCMAC, LOGL_INFO, "TX: START TFI: %u TLLI: 0x%08x Immediate Assignment Downlink (PCH)\n", tbf->tfi, tbf->tlli);
+	/* use request reference that has maximum distance to current time,
+	 * so the assignment will not conflict with possible RACH requests. */
+	rc = write_immediate_assignment_downlink(imm_ass, 125, (tbf->pdch[tbf->first_ts]->last_rts_fn + 21216) % 2715648, tbf->ta, tbf->arfcn, tbf->first_ts, tbf->tsc, tbf->tfi, tbf->tlli, poll, tbf->poll_fn);
+	if (rc < 0)
+		return;
+
+	pcu_l1if_tx_pch(imm_ass, imsi);
+}
+
+/* depending on the current TBF, we assign on PACCH or AGCH */
+void gprs_rlcmac_trigger_downlink_assignment(struct gprs_rlcmac_tbf *tbf,
+	struct gprs_rlcmac_tbf *old_tbf, char *imsi)
+{
+#ifdef DEBUG_DL_ASS_IDLE
+	strncpy(debug_imsi, imsi);
+	LOGP(DRLCMAC, LOGL_ERROR, "**** DEBUGGING DOWNLINK ASSIGNMENT ****\n");
+#endif
+
+	/* stop pending timer */
+	tbf_timer_stop(tbf);
+
+	/* check for downlink tbf:  */
+	if (old_tbf) {
+#ifdef DEBUG_DL_ASS_IDLE
+		LOGP(DRLCMAC, LOGL_ERROR, "We must wait for current TBF to be "
+			"released.\n");
+		/* wait one second until assignment */
+		tbf_timer_start(tbf, 1234, 1,0);
+#else
+		LOGP(DRLCMAC, LOGL_DEBUG, "Send dowlink assignment on "
+			"PACCH, because %s TBF=%d exists for TLLI=0x%08x\n",
+			(old_tbf->direction == GPRS_RLCMAC_UL_TBF)
+				? "UL" : "DL", old_tbf->tfi, old_tbf->tlli);
+		old_tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_SEND_ASS;
+		/* use TA from old TBF */
+		tbf->ta = old_tbf->ta;
+		/* change state */
+		tbf_new_state(tbf, GPRS_RLCMAC_ASSIGN);
+#endif
+	} else {
+		LOGP(DRLCMAC, LOGL_DEBUG, "Send dowlink assignment for TBF=%d on PCH, no TBF exist (IMSI=%s)\n", tbf->tfi, imsi);
+		if (!imsi || strlen(imsi) < 3) {
+			LOGP(DRLCMAC, LOGL_ERROR, "No valid IMSI!\n");
+			return;
+		}
+		/* change state */
+		tbf_new_state(tbf, GPRS_RLCMAC_ASSIGN);
+		/* send immediate assignment */
+		gprs_rlcmac_downlink_assignment(tbf, 0, imsi);
+		/* send immediate assignment */
+		gprs_rlcmac_downlink_assignment(tbf, 0, imsi);
+		/* start timer */
+		tbf_timer_start(tbf, 0, Tassign_agch);
+	}
+								                }
+