aboutsummaryrefslogtreecommitdiffstats
path: root/src/gprs_rlcmac_data.cpp
blob: d5bebff1afa09047b7bcec479f4b06ea74015ba2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
/* 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 <pcu_l1_if.h>
#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 */
	{ 0,		0,		0  },
	{ 23,		23,		20 }, /* CS-1 */
	{ 34,		33,		30 }, /* CS-2 */
	{ 40,		39,		36 }, /* CS-3 */
	{ 54,		53,		50 }, /* CS-4 */
};


extern void *tall_pcu_ctx;

/* After sending these frames, we poll for ack/nack. */
#define POLL_ACK_AFTER_FRAMES 20

/* If acknowledgement to uplink/downlink assignmentshould be polled */
#define POLLING_ASSIGNMENT_DL 1
#define POLLING_ASSIGNMENT_UL 1


static void gprs_rlcmac_downlink_assignment(
	gprs_rlcmac_tbf *tbf, uint8_t poll,
	const char *imsi);

static int gprs_rlcmac_diag(struct gprs_rlcmac_tbf *tbf)
{
	return tbf->rlcmac_diag();
}

int gprs_rlcmac_poll_timeout(struct gprs_rlcmac_bts *bts, 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) {
		if (!(tbf->state_flags & (1 << GPRS_RLCMAC_FLAG_TO_UL_ACK))) {
			LOGP(DRLCMAC, LOGL_NOTICE, "- Timeout for polling "
				"PACKET CONTROL ACK for PACKET UPLINK ACK\n");
			gprs_rlcmac_diag(tbf);
			tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_TO_UL_ACK);
		}
		tbf->ul_ack_state = GPRS_RLCMAC_UL_ACK_NONE;
		debug_diagram(bts->bts, tbf->diag, "timeout UL-ACK");
		if (tbf->state_is(GPRS_RLCMAC_FINISHED)) {
			tbf->dir.ul.n3103++;
			if (tbf->dir.ul.n3103 == bts->n3103) {
				LOGP(DRLCMAC, LOGL_NOTICE,
					"- N3103 exceeded\n");
				debug_diagram(bts->bts, tbf->diag, "N3103 exceeded");
				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) {
		if (!(tbf->state_flags & (1 << GPRS_RLCMAC_FLAG_TO_UL_ASS))) {
			LOGP(DRLCMAC, LOGL_NOTICE, "- Timeout for polling "
				"PACKET CONTROL ACK for PACKET UPLINK "
				"ASSIGNMENT.\n");
			gprs_rlcmac_diag(tbf);
			tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_TO_UL_ASS);
		}
		tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_NONE;
		debug_diagram(tbf->bts, tbf->diag, "timeout UL-ASS");
		tbf->n3105++;
		if (tbf->n3105 == bts->n3105) {
			LOGP(DRLCMAC, LOGL_NOTICE, "- N3105 exceeded\n");
			debug_diagram(bts->bts, tbf->diag, "N3105 exceeded");
			tbf_new_state(tbf, GPRS_RLCMAC_RELEASING);
			tbf_timer_start(tbf, 3195, bts->t3195, 0);
			return 0;
		}
		/* reschedule UL assignment */
		tbf->ul_ass_state = GPRS_RLCMAC_UL_ASS_SEND_ASS;
	} else
	if (tbf->dl_ass_state == GPRS_RLCMAC_DL_ASS_WAIT_ACK) {
		if (!(tbf->state_flags & (1 << GPRS_RLCMAC_FLAG_TO_DL_ASS))) {
			LOGP(DRLCMAC, LOGL_NOTICE, "- Timeout for polling "
				"PACKET CONTROL ACK for PACKET DOWNLINK "
				"ASSIGNMENT.\n");
			gprs_rlcmac_diag(tbf);
			tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_TO_DL_ASS);
		}
		tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_NONE;
		debug_diagram(bts->bts, tbf->diag, "timeout DL-ASS");
		tbf->n3105++;
		if (tbf->n3105 == bts->n3105) {
			LOGP(DRLCMAC, LOGL_NOTICE, "- N3105 exceeded\n");
			debug_diagram(bts->bts, tbf->diag, "N3105 exceeded");
			tbf_new_state(tbf, GPRS_RLCMAC_RELEASING);
			tbf_timer_start(tbf, 3195, bts->t3195, 0);
			return 0;
		}
		/* reschedule DL assignment */
		tbf->dl_ass_state = GPRS_RLCMAC_DL_ASS_SEND_ASS;
	} else
	if (tbf->direction == GPRS_RLCMAC_DL_TBF) {
		if (!(tbf->state_flags & (1 << GPRS_RLCMAC_FLAG_TO_DL_ACK))) {
			LOGP(DRLCMAC, LOGL_NOTICE, "- Timeout for polling "
				"PACKET DOWNLINK ACK.\n");
			gprs_rlcmac_diag(tbf);
			tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_TO_DL_ACK);
		}
		debug_diagram(bts->bts, tbf->diag, "timeout DL-ACK");
		tbf->n3105++;
		if (tbf->n3105 == bts->n3105) {
			LOGP(DRLCMAC, LOGL_NOTICE, "- N3105 exceeded\n");
			debug_diagram(bts->bts, tbf->diag, "N3105 exceeded");
			tbf_new_state(tbf, GPRS_RLCMAC_RELEASING);
			tbf_timer_start(tbf, 3195, bts->t3195, 0);
			return 0;
		}
		/* resend IMM.ASS on CCCH on timeout */
		if ((tbf->state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH))
		 && !(tbf->state_flags & (1 << GPRS_RLCMAC_FLAG_DL_ACK))) {
			LOGP(DRLCMAC, LOGL_DEBUG, "Re-send dowlink assignment "
				"for TBF=%d on PCH (IMSI=%s)\n", tbf->tfi,
				tbf->dir.dl.imsi);
			/* send immediate assignment */
			gprs_rlcmac_downlink_assignment(tbf, 0, tbf->dir.dl.imsi);
			tbf->dir.dl.wait_confirm = 1;
		}
	} else
		LOGP(DRLCMAC, LOGL_ERROR, "- Poll Timeout, but no event!\n");

	return 0;
}

#ifdef DEBUG_DL_ASS_IDLE
	char debug_imsi[16];
#endif

/*
 * UL data block flow
 */

struct msgb *gprs_rlcmac_send_uplink_ack(
	struct gprs_rlcmac_tbf *tbf,
	uint32_t fn)
{
	int final = (tbf->state_is(GPRS_RLCMAC_FINISHED));
	gprs_rlcmac_bts *bts = tbf->bts->bts_data();
	struct msgb *msg;

	if (final) {
		if (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;
		}
		if (tbf->bts->sba()->find(tbf->trx_no, tbf->control_ts, (fn + 13) % 2715648)) {
			LOGP(DRLCMACUL, LOGL_DEBUG, "Polling is already "
				"scheduled for single block allocation...\n");
			return NULL;
		}
	}

	msg = msgb_alloc(23, "rlcmac_ul_ack");
	if (!msg)
		return NULL;
	bitvec *ack_vec = bitvec_alloc(23);
	if (!ack_vec) {
		msgb_free(msg);
		return NULL;
	}
	bitvec_unhex(ack_vec,
		"2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	RlcMacDownlink_t * mac_control_block = (RlcMacDownlink_t *)talloc_zero(tall_pcu_ctx, RlcMacDownlink_t);
	Encoding::write_packet_uplink_ack(bts, mac_control_block, tbf, final);
	encode_gsm_rlcmac_downlink(ack_vec, mac_control_block);
	bitvec_pack(ack_vec, msgb_put(msg, 23));
	bitvec_free(ack_vec);
	talloc_free(mac_control_block);

	/* 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;
	debug_diagram(bts->bts, tbf->diag, "send UL-ACK");

	return msg;
}

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;
	gprs_rlcmac_bts *bts = tbf->bts->bts_data();

#if POLLING_ASSIGNMENT_UL == 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;
	}
	if (tbf->bts->sba()->find(tbf->trx_no, tbf->control_ts, (fn + 13) % 2715648)) {
		LOGP(DRLCMACUL, LOGL_DEBUG, "Polling is already scheduled for "
			"single block allocation...\n");
			return NULL;
	}
#endif

	/* on down TBF we get the uplink TBF to be assigned. */
	if (tbf->direction == GPRS_RLCMAC_DL_TBF)
		new_tbf = tbf->bts->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;
	}

	msg = msgb_alloc(23, "rlcmac_ul_ass");
	if (!msg)
		return NULL;
	LOGP(DRLCMAC, LOGL_INFO, "TBF: START TFI: %u TLLI: 0x%08x Packet Uplink Assignment (PACCH)\n", new_tbf->tfi, new_tbf->tlli);
	bitvec *ass_vec = bitvec_alloc(23);
	if (!ass_vec) {
		msgb_free(msg);
		return NULL;
	}
	bitvec_unhex(ass_vec,
		"2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	Encoding::write_packet_uplink_assignment(bts, ass_vec, tbf->tfi,
		(tbf->direction == GPRS_RLCMAC_DL_TBF), tbf->tlli,
		tbf->tlli_valid, new_tbf, POLLING_ASSIGNMENT_UL, bts->alpha,
		bts->gamma, -1);
	bitvec_pack(ass_vec, msgb_put(msg, 23));
	RlcMacDownlink_t * mac_control_block = (RlcMacDownlink_t *)talloc_zero(tall_pcu_ctx, RlcMacDownlink_t);
	LOGP(DRLCMAC, LOGL_DEBUG, "+++++++++++++++++++++++++ TX : Packet Uplink Assignment +++++++++++++++++++++++++\n");
	decode_gsm_rlcmac_downlink(ass_vec, mac_control_block);
	LOGPC(DCSN1, LOGL_NOTICE, "\n");
	LOGP(DRLCMAC, LOGL_DEBUG, "------------------------- TX : Packet Uplink Assignment -------------------------\n");
	bitvec_free(ass_vec);
	talloc_free(mac_control_block);

#if POLLING_ASSIGNMENT_UL == 1
	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
	debug_diagram(bts->bts, tbf->diag, "send UL-ASS");

	return msg;
}

int gprs_rlcmac_rcv_rach(struct gprs_rlcmac_bts *bts,
		uint8_t ra, uint32_t Fn, int16_t qta)
{
	struct gprs_rlcmac_tbf *tbf;
	uint8_t trx, ts = 0;
	int8_t tfi; /* must be signed */
	uint8_t sb = 0;
	uint32_t sb_fn = 0;
	int rc;
	uint8_t plen;

	LOGP(DRLCMAC, LOGL_DEBUG, "MS requests UL TBF on RACH, so we provide "
		"one:\n");
	if ((ra & 0xf8) == 0x70) {
		LOGP(DRLCMAC, LOGL_DEBUG, "MS requests single block "
			"allocation\n");
		sb = 1;
	} else if (bts->force_two_phase) {
		LOGP(DRLCMAC, LOGL_DEBUG, "MS requests single phase access, "
			"but we force two phase access\n");
		sb = 1;
	}
	if (qta < 0)
		qta = 0;
	if (qta > 252)
		qta = 252;
	if (sb) {
		rc = bts->bts->sba()->alloc(&trx, &ts, &sb_fn, qta >> 2);
		if (rc < 0)
			return rc;
		LOGP(DRLCMAC, LOGL_DEBUG, "RX: [PCU <- BTS] RACH qbit-ta=%d "
			"ra=0x%02x, Fn=%d (%d,%d,%d)\n", qta, ra, Fn,
			(Fn / (26 * 51)) % 32, Fn % 51, Fn % 26);
		LOGP(DRLCMAC, LOGL_INFO, "TX: Immediate Assignment Uplink "
			"(AGCH)\n");
	} else {
		// Create new TBF
		#warning "Copy and pate with other routines.."
		tfi = tfi_find_free(bts, GPRS_RLCMAC_UL_TBF, &trx, -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(bts, NULL, GPRS_RLCMAC_UL_TBF, tfi, trx, 0, 1);
		if (!tbf) {
			LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH ressource\n");
			/* FIXME: send reject */
			return -EBUSY;
		}
		tbf->ta = qta >> 2;
		tbf_new_state(tbf, GPRS_RLCMAC_FLOW);
		tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_CCCH);
		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=0x%02x, 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);
	}
	bitvec *immediate_assignment = bitvec_alloc(22) /* without plen */;
	bitvec_unhex(immediate_assignment,
		"2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	if (sb)
		plen = Encoding::write_immediate_assignment(bts, immediate_assignment, 0, ra,
			Fn, qta >> 2, bts->trx[trx].arfcn, ts,
			bts->trx[trx].pdch[ts].tsc, 0, 0, 0, 0, sb_fn, 1,
			bts->alpha, bts->gamma, -1);
	else
		plen = Encoding::write_immediate_assignment(bts, immediate_assignment, 0, ra,
			Fn, tbf->ta, tbf->arfcn, tbf->first_ts, tbf->tsc,
			tbf->tfi, tbf->dir.ul.usf[tbf->first_ts], 0, 0, 0, 0,
			bts->alpha, bts->gamma, -1);
	pcu_l1if_tx_agch(immediate_assignment, plen);
	bitvec_free(immediate_assignment);

	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 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;
	int first_fin_ack = 0;
	gprs_rlcmac_bts *bts = tbf->bts->bts_data();

	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_is(GPRS_RLCMAC_FINISHED)
	 || ((tbf->dir.dl.v_s - tbf->dir.dl.v_a) & mod_sns) == tbf->ws) {
	 	int resend = 0;

		if (tbf->state_is(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_DEBUG, "- MS acked all blocks, "
				"so we re-transmit final block!\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];
#warning "Selection of the CS doesn't belong here"
	if (tbf->cs == 0) {
		tbf->cs = bts->initial_cs_dl;
		if (tbf->cs < 1 || tbf->cs > 4)
			tbf->cs = 1;
	}
	block_length = gprs_rlcmac_cs[tbf->cs].block_length;
	block_data = gprs_rlcmac_cs[tbf->cs].block_data;
	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_dl_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_dl_bw(tbf, tbf->llc_length);
		/* reset LLC frame */
		tbf->llc_index = tbf->llc_length = 0;
		/* dequeue next LLC frame, if any */
		msg = tbf->llc_dequeue(gprs_bssgp_pcu_current_bctx());
		if (msg) {
			LOGP(DRLCMACDL, LOGL_INFO, "- Dequeue next LLC for "
				"TBF=%d (len=%d)\n", tbf->tfi, msg->len);
			tbf->update_llc_frame(msg);
			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 */
			first_fin_ack = 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 || 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 (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 if (tbf->bts->sba()->find(tbf->trx_no, ts, (fn + 13) % 2715648))
			LOGP(DRLCMAC, LOGL_DEBUG, "Polling cannot be "
				"sheduled, because single block alllocation "
				"already exists\n");
		else  {
			LOGP(DRLCMAC, LOGL_DEBUG, "Polling sheduled in this "
				"TS %d\n", ts);
			tbf->dir.dl.tx_counter = 0;
			/* 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;

#ifdef DEBUG_DIAGRAM
			debug_diagram(bts->bts, tbf->diag, "poll DL-ACK");
			if (first_fin_ack)
				debug_diagram(bts->bts, tbf->diag, "(is first FINAL)");
			if (rh->fbi)
				debug_diagram(bts->bts, tbf->diag, "(FBI is set)");
#endif

			/* 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;
	uint16_t lost = 0, received = 0;

	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)) {
			/* 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 */
		}
		/* 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);
				if (tbf->dir.dl.v_b[bsn & mod_sns_half]
								!= 'A')
					received++;
				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';
				lost++;
			}
		}
		/* report lost and received packets */
		gprs_rlcmac_received_lost(tbf, received, lost);

		/* 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_is(GPRS_RLCMAC_FINISHED)
		 && tbf->dir.dl.v_s == tbf->dir.dl.v_a) {
			LOGP(DRLCMACDL, LOGL_NOTICE, "Received acknowledge of "
				"all blocks, but without final ack "
				"inidcation (don't worry)\n");
		}
		return 0;
	}

	LOGP(DRLCMACDL, LOGL_DEBUG, "- Final ACK received.\n");
	debug_diagram(tbf->bts, tbf->diag, "got Final ACK");
	/* range V(A)..V(S)-1 */
	for (bsn = tbf->dir.dl.v_a; bsn != tbf->dir.dl.v_s;
	     bsn = (bsn + 1) & mod_sns) {
		if (tbf->dir.dl.v_b[bsn & mod_sns_half] != 'A')
			received++;
	}

	/* report all outstanding packets as received */
	gprs_rlcmac_received_lost(tbf, received, lost);

	/* check for LLC PDU in the LLC Queue */
	msg = tbf->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 */
		debug_diagram(bts->bts, tbf->diag, "start T3193");
		tbf_timer_start(tbf, 3193,
			tbf->bts->bts_data()->t3193_msec / 1000,
			(tbf->bts->bts_data()->t3193_msec % 1000) * 1000);
		tbf_new_state(tbf, GPRS_RLCMAC_WAIT_RELEASE);

		return 0;
	}
	#warning "Copy and paste on the sender path"
	tbf->update_llc_frame(msg);
	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->state_flags &= GPRS_RLCMAC_FLAG_TO_MASK; /* keep TO flags */
	tbf->state_flags &= ~(1 << GPRS_RLCMAC_FLAG_CCCH);
	tbf->update();
	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;
	gprs_rlcmac_bts *bts = tbf->bts->bts_data();
	int poll_ass_dl = POLLING_ASSIGNMENT_DL;

	if (poll_ass_dl && tbf->direction == GPRS_RLCMAC_DL_TBF
	 && tbf->control_ts != tbf->first_common_ts) {
		LOGP(DRLCMAC, LOGL_NOTICE, "Cannot poll for downlink "
			"assigment, because MS cannot reply. (control TS=%d, "
			"first common TS=%d)\n", tbf->control_ts,
			tbf->first_common_ts);
		poll_ass_dl = 0;
	}
	if (poll_ass_dl) {
		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;
		}
		if (tbf->bts->sba()->find(tbf->trx_no, tbf->control_ts, (fn + 13) % 2715648)) {
			LOGP(DRLCMACUL, LOGL_DEBUG, "Polling is already "
				"scheduled for single block allocation...\n");
			return NULL;
		}
	}

	/* 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->bts->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;
	}

	msg = msgb_alloc(23, "rlcmac_dl_ass");
	if (!msg)
		return NULL;
	bitvec *ass_vec = bitvec_alloc(23);
	if (!ass_vec) {
		msgb_free(msg);
		return NULL;
	}
	bitvec_unhex(ass_vec,
		"2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	LOGP(DRLCMAC, LOGL_INFO, "TBF: START TFI: %u TLLI: 0x%08x Packet Downlink Assignment (PACCH)\n", new_tbf->tfi, new_tbf->tlli);
	RlcMacDownlink_t * mac_control_block = (RlcMacDownlink_t *)talloc_zero(tall_pcu_ctx, RlcMacDownlink_t);
	Encoding::write_packet_downlink_assignment(mac_control_block, tbf->tfi,
		(tbf->direction == GPRS_RLCMAC_DL_TBF), new_tbf,
		poll_ass_dl, bts->alpha, bts->gamma, -1, 0);
	LOGP(DRLCMAC, LOGL_DEBUG, "+++++++++++++++++++++++++ TX : Packet Downlink Assignment +++++++++++++++++++++++++\n");
	encode_gsm_rlcmac_downlink(ass_vec, mac_control_block);
	LOGPC(DCSN1, LOGL_NOTICE, "\n");
	LOGP(DRLCMAC, LOGL_DEBUG, "------------------------- TX : Packet Downlink Assignment -------------------------\n");
	bitvec_pack(ass_vec, msgb_put(msg, 23));
	bitvec_free(ass_vec);
	talloc_free(mac_control_block);

	if (poll_ass_dl) {
		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);
		/* stop pending assignment timer */
		new_tbf->stop_timer();

	}
	debug_diagram(bts->bts, tbf->diag, "send DL-ASS");

	return msg;
}

static void gprs_rlcmac_downlink_assignment(
	gprs_rlcmac_tbf *tbf, uint8_t poll,
	const char *imsi)
{
	gprs_rlcmac_bts *bts = tbf->bts->bts_data();
	int plen;

	debug_diagram(bts->bts, tbf->diag, "IMM.ASS (PCH)");
	LOGP(DRLCMAC, LOGL_INFO, "TX: START TFI: %u TLLI: 0x%08x Immediate Assignment Downlink (PCH)\n", tbf->tfi, tbf->tlli);
	bitvec *immediate_assignment = bitvec_alloc(22); /* without plen */
	bitvec_unhex(immediate_assignment, "2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	/* use request reference that has maximum distance to current time,
	 * so the assignment will not conflict with possible RACH requests. */
	plen = Encoding::write_immediate_assignment(bts, immediate_assignment, 1, 125,
		(tbf->pdch[tbf->first_ts]->last_rts_fn + 21216) % 2715648, tbf->ta,
		tbf->arfcn, tbf->first_ts, tbf->tsc, tbf->tfi, 0, tbf->tlli, poll,
		tbf->poll_fn, 0, bts->alpha, bts->gamma, -1);
	pcu_l1if_tx_pch(immediate_assignment, plen, imsi);
	bitvec_free(immediate_assignment);
}

/* 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, const char *imsi)
{
#ifdef DEBUG_DL_ASS_IDLE
	strncpy(debug_imsi, imsi);
	LOGP(DRLCMAC, LOGL_ERROR, "**** DEBUGGING DOWNLINK ASSIGNMENT ****\n");
#endif

	/* stop pending timer */
	tbf->stop_timer();

	/* 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);
		tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_PACCH);
		/* start timer */
		tbf_timer_start(tbf, 0, Tassign_pacch);
#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);
		tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_CCCH);
		strncpy(tbf->dir.dl.imsi, imsi, sizeof(tbf->dir.dl.imsi));
		/* send immediate assignment */
		gprs_rlcmac_downlink_assignment(tbf, 0, imsi);
		tbf->dir.dl.wait_confirm = 1;
	}
}

int gprs_rlcmac_imm_ass_cnf(BTS *bts, uint8_t *data, uint32_t fn)
{
	struct gprs_rlcmac_tbf *tbf;
	uint8_t plen;
	uint32_t tlli;

	/* move to IA Rest Octets */
	plen = data[0] >> 2;
	data += 1 + plen;

	if ((*data & 0xf0) != 0xd0) {
		LOGP(DRLCMAC, LOGL_ERROR, "Got IMM.ASS confirm, but rest "
			"octets do not start with bit sequence 'HH01' "
			"(Packet Downlink Assignment)\n");
		return -EINVAL;
	}

	/* get TLLI from downlink assignment */
	tlli = (*data++) << 28;
	tlli |= (*data++) << 20;
	tlli |= (*data++) << 12;
	tlli |= (*data++) << 4;
	tlli |= (*data++) >> 4;

	tbf = bts->tbf_by_tlli(tlli, GPRS_RLCMAC_DL_TBF);
	if (!tbf) {
		LOGP(DRLCMAC, LOGL_ERROR, "Got IMM.ASS confirm, but TLLI=%08x "
			"does not exit\n", tlli);
		return -EINVAL;
	}

	LOGP(DRLCMAC, LOGL_DEBUG, "Got IMM.ASS confirm for TLLI=%08x\n", tlli);

	if (tbf->dir.dl.wait_confirm) {
		tbf_timer_start(tbf, 0, Tassign_agch);
	}

	return 0;
}