/* gprs_rlcmac.cpp
 *
 * 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 <pcu_l1_if.h>
#include <gprs_rlcmac.h>
#include <gsmL1prim.h>

LLIST_HEAD(gprs_rlcmac_tbfs);
void *rlcmac_tall_ctx;
LLIST_HEAD(block_queue);

/* FIXME: spread ressources on multiple TRX */
int tfi_alloc(uint8_t *_trx, uint8_t *_ts)
{
	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
	struct gprs_rlcmac_pdch *pdch;
	uint8_t trx, ts, tfi;

	for (trx = 0; trx < 8; trx++) {
		for (ts = 0; ts < 8; ts++) {
			pdch = &bts->trx[trx].pdch[ts];
			if (!pdch->enable)
				continue;
			break;
		}
		if (ts < 8)
			break;
	}
	if (trx == 8) {
		LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH available.\n");
		return -EINVAL;
	}


	LOGP(DRLCMAC, LOGL_DEBUG, "Searching for first unallocated TFI: "
		"TRX=%d TS=%d\n", trx, ts);
	for (tfi = 0; tfi < 32; tfi++) {
		if (!pdch->tbf[tfi])
			break;
	}
	
	if (tfi < 32) {
		LOGP(DRLCMAC, LOGL_DEBUG, " Found TFI=%d.\n", tfi);
		*_trx = trx;
		*_ts = ts;
		return tfi;
	}
	LOGP(DRLCMAC, LOGL_NOTICE, "No TFI available.\n");

	return -1;
}

int find_free_usf(uint8_t trx, uint8_t ts)
{
	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
	struct gprs_rlcmac_pdch *pdch;
	struct gprs_rlcmac_tbf *tbf;
	uint8_t usf_map = 0;
	uint8_t tfi, usf;

	if (trx >= 8 || ts >= 8)
		return -EINVAL;
	pdch = &bts->trx[trx].pdch[ts];

	/* make map of used USF */
	for (tfi = 0; tfi < 32; tfi++) {
		tbf = pdch->tbf[tfi];
		if (!tbf)
			continue;
		if (tbf->direction != GPRS_RLCMAC_UL_TBF)
			continue;
		usf_map |= (1 << tbf->dir.ul.usf);
	}

	/* look for USF, don't use USF=7 */
	for (usf = 0; usf < 7; usf++) {
		if (!(usf_map & (1 << usf))) {
			LOGP(DRLCMAC, LOGL_DEBUG, " Found USF=%d.\n", usf);
			return usf;
		}
	}
	LOGP(DRLCMAC, LOGL_NOTICE, "No USF available.\n");

	return -1;
}

/* lookup TBF Entity (by TFI) */
#warning FIXME: use pdch instance by trx and ts, because tfi is local
struct gprs_rlcmac_tbf *tbf_by_tfi(uint8_t tfi)
{
	struct gprs_rlcmac_tbf *tbf;

	llist_for_each_entry(tbf, &gprs_rlcmac_tbfs, list) {
		if (tbf->tfi == tfi)
			return tbf;
	}
	return NULL;
}

struct gprs_rlcmac_tbf *tbf_by_tlli(uint32_t tlli)
{
	struct gprs_rlcmac_tbf *tbf;
	llist_for_each_entry(tbf, &gprs_rlcmac_tbfs, list) {
		if ((tbf->tlli == tlli)&&(tbf->direction == GPRS_RLCMAC_UL_TBF))
			return tbf;
	}
	return NULL;
}

struct gprs_rlcmac_tbf *tbf_alloc(uint8_t tfi, uint8_t trx, uint8_t ts)
{
	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
	struct gprs_rlcmac_pdch *pdch;
	struct gprs_rlcmac_tbf *tbf;

	LOGP(DRLCMAC, LOGL_INFO, "********** TBF starts here **********\n");
	LOGP(DRLCMAC, LOGL_INFO, "Allocating TBF with TFI=%d.\n", tfi);

	if (trx >= 8 || ts >= 8 || tfi >= 32)
		return NULL;
	pdch = &bts->trx[trx].pdch[ts];

	tbf = talloc_zero(rlcmac_tall_ctx, struct gprs_rlcmac_tbf);
	if (!tbf)
		return NULL;

	tbf->tfi = tfi;
	tbf->trx = trx;
	tbf->ts = ts;
	tbf->arfcn = bts->trx[trx].arfcn;
	tbf->tsc = bts->trx[trx].pdch[ts].tsc;
	tbf->ws = 64;
	tbf->sns = 128;
	llist_add(&tbf->list, &gprs_rlcmac_tbfs);
	pdch->tbf[tfi] = tbf;

	return tbf;
}

void tbf_free(struct gprs_rlcmac_tbf *tbf)
{
	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
	struct gprs_rlcmac_pdch *pdch;

	LOGP(DRLCMAC, LOGL_INFO, "Free TBF with TFI=%d.\n", tbf->tfi);
	LOGP(DRLCMAC, LOGL_INFO, "********** TBF ends here **********\n");
	tbf_timer_stop(tbf);
	pdch = &bts->trx[tbf->trx].pdch[tbf->ts];
	pdch->tbf[tbf->tfi] = NULL;
	llist_del(&tbf->list);
	talloc_free(tbf);
}


static void tbf_timer_cb(void *_tbf)
{
	struct gprs_rlcmac_tbf *tbf = (struct gprs_rlcmac_tbf *)_tbf;

	LOGP(DRLCMAC, LOGL_DEBUG, "TBF timer %u expired.\n", tbf->T);

	tbf->num_T_exp++;

	switch (tbf->T) {
	case 3169:
		LOGP(DRLCMAC, LOGL_DEBUG, "TBF will be freed due to timeout\n");
		/* free TBF */
		tbf_free(tbf);
		break;
	case 3103:
		if (++tbf->dir.ul.n3103 == N3103_MAX) {
			LOGP(DRLCMAC, LOGL_DEBUG, "Final ACK will be resent "
				"due to timeout\n");
			/* timeout for polling with final ack message, */
			/* trigger sending at next RTS */
			tbf->dir.ul.substate = GPRS_RLCMAC_UL_SEND_ACK;
		} else {
			LOGP(DRLCMAC, LOGL_DEBUG, "Too many timeouts on final "
				"ACK, starting T3169\n");
			/* restart T3169, so we can be sure that after expiry,
			 * the mobile has timed out and wiil not transmit
			 * anymore */
			tbf->state = GPRS_RLCMAC_RELEASING;
		        tbf_timer_start(tbf, 3169, T3169);
		}
		break;
	default:
		LOGP(DRLCMAC, LOGL_ERROR, "Timer expired in unknown mode: %u\n",
			tbf->T);
	}
}

void tbf_timer_start(struct gprs_rlcmac_tbf *tbf, unsigned int T,
				unsigned int seconds)
{
	if (!osmo_timer_pending(&tbf->timer))
		LOGP(DRLCMAC, LOGL_DEBUG, "Starting TBF timer %u.\n", T);
	else
		LOGP(DRLCMAC, LOGL_DEBUG, "Restarting TBF timer %u while old "
			"timer %u pending \n", T, tbf->T);

	tbf->T = T;
	tbf->num_T_exp = 0;

	/* Tunning timers can be safely re-scheduled. */
	tbf->timer.data = tbf;
	tbf->timer.cb = &tbf_timer_cb;

	osmo_timer_schedule(&tbf->timer, seconds, 0);
}

void tbf_timer_stop(struct gprs_rlcmac_tbf *tbf)
{
	if (osmo_timer_pending(&tbf->timer)) {
		LOGP(DRLCMAC, LOGL_DEBUG, "Stopping TBF timer %u.\n", tbf->T);
		osmo_timer_del(&tbf->timer);
	}
}

static void tbf_gsm_timer_cb(void *_tbf)
{
	struct gprs_rlcmac_tbf *tbf = (struct gprs_rlcmac_tbf *)_tbf;

	tbf->num_fT_exp++;

	switch (tbf->fT) {
	case 0:
		// This is timer for delay RLC/MAC data sending after Downlink Immediate Assignment on CCCH.
		gprs_rlcmac_segment_llc_pdu(tbf);
		LOGP(DRLCMAC, LOGL_NOTICE, "TBF: [DOWNLINK] END TFI: %u TLLI: 0x%08x \n", tbf->tfi, tbf->tlli);
		tbf_free(tbf);
		break;
	default:
		LOGP(DRLCMAC, LOGL_NOTICE, "Timer expired in unknown mode: %u \n", tbf->fT);
	}
}

static void tbf_gsm_timer_start(struct gprs_rlcmac_tbf *tbf, unsigned int fT,
				int frames)
{
	if (osmo_gsm_timer_pending(&tbf->gsm_timer))
		LOGP(DRLCMAC, LOGL_NOTICE, "Starting TBF timer %u while old timer %u pending \n", fT, tbf->fT);
	tbf->fT = fT;
	tbf->num_fT_exp = 0;

	/* FIXME: we should do this only once ? */
	tbf->gsm_timer.data = tbf;
	tbf->gsm_timer.cb = &tbf_gsm_timer_cb;

	osmo_gsm_timer_schedule(&tbf->gsm_timer, frames);
}

void gprs_rlcmac_enqueue_block(bitvec *block, int len)
{
	struct msgb *msg = msgb_alloc(len, "rlcmac_dl");
	bitvec_pack(block, msgb_put(msg, len));
	msgb_enqueue(&block_queue, msg);
}

void  write_packet_downlink_assignment(bitvec * dest, uint8_t tfi, uint32_t tlli, uint16_t arfcn, uint8_t tn, uint8_t ta, uint8_t tsc)
{
	// TODO We should use our implementation of encode RLC/MAC Control messages.
	unsigned wp = 0;
	int i;
	bitvec_write_field(dest, wp,0x1,2);  // Payload Type
	bitvec_write_field(dest, wp,0x0,2);  // Uplink block with TDMA framenumber
	bitvec_write_field(dest, wp,0x1,1);  // Suppl/Polling Bit
	bitvec_write_field(dest, wp,0x1,3);  // Uplink state flag
	bitvec_write_field(dest, wp,0x2,6);  // MESSAGE TYPE
	bitvec_write_field(dest, wp,0x0,2);  // Page Mode

	bitvec_write_field(dest, wp,0x0,1); // switch PERSIST_LEVEL: off
	bitvec_write_field(dest, wp,0x0,1); // switch TFI : on
	bitvec_write_field(dest, wp,0x0,1); // switch UPLINK TFI : on
	bitvec_write_field(dest, wp,tfi-1,5); // TFI

	bitvec_write_field(dest, wp,0x0,1); // Message escape
	bitvec_write_field(dest, wp,0x0,2); // Medium Access Method: Dynamic Allocation
	bitvec_write_field(dest, wp,0x0,1); // RLC acknowledged mode

	bitvec_write_field(dest, wp,0x0,1); // the network establishes no new downlink TBF for the mobile station
	bitvec_write_field(dest, wp,0x80 >> tn,8); // timeslot(s)

	bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_VALUE = on
	bitvec_write_field(dest, wp,ta,6); // TIMING_ADVANCE_VALUE
	bitvec_write_field(dest, wp,0x0,1); // switch TIMING_ADVANCE_INDEX = off

	bitvec_write_field(dest, wp,0x0,1); // switch POWER CONTROL = off
	bitvec_write_field(dest, wp,0x1,1); // Frequency Parameters information elements = present

	bitvec_write_field(dest, wp,tsc,3); // Training Sequence Code (TSC) = 2
	bitvec_write_field(dest, wp,0x0,2); // ARFCN = present
	bitvec_write_field(dest, wp,arfcn,10); // ARFCN

	bitvec_write_field(dest, wp,0x1,1); // switch TFI   : on
	bitvec_write_field(dest, wp,tfi,5);// TFI

	bitvec_write_field(dest, wp,0x1,1); // Power Control Parameters IE = present
	bitvec_write_field(dest, wp,0x0,4); // ALPHA power control parameter
	for (i = 0; i < 8; i++)
		bitvec_write_field(dest, wp,(tn == i),1); // switch GAMMA_TN[i] = on or off
	bitvec_write_field(dest, wp,0x0,5); // GAMMA_TN[tn]

	bitvec_write_field(dest, wp,0x0,1); // TBF Starting TIME IE not present
	bitvec_write_field(dest, wp,0x0,1); // Measurement Mapping struct not present
	bitvec_write_field(dest, wp,0x0,1);
}

void  write_packet_uplink_assignment(bitvec * dest, uint8_t tfi, uint32_t tlli)
{
	// TODO We should use our implementation of encode RLC/MAC Control messages.
	unsigned wp = 0;
	bitvec_write_field(dest, wp,0x1,2);  // Payload Type
	bitvec_write_field(dest, wp,0x0,2);  // Uplink block with TDMA framenumber
	bitvec_write_field(dest, wp,0x1,1);  // Suppl/Polling Bit
	bitvec_write_field(dest, wp,0x1,3);  // Uplink state flag


	bitvec_write_field(dest, wp,0xa,6);  // MESSAGE TYPE

	bitvec_write_field(dest, wp,0x0,2);  // Page Mode

	bitvec_write_field(dest, wp,0x0,1); // switch PERSIST_LEVEL: off
	bitvec_write_field(dest, wp,0x2,2); // switch TLLI   : on
	bitvec_write_field(dest, wp,tlli,32); // TLLI

	bitvec_write_field(dest, wp,0x0,1); // Message escape
	bitvec_write_field(dest, wp,0x0,2); // CHANNEL_CODING_COMMAND
	bitvec_write_field(dest, wp,0x0,1); // TLLI_BLOCK_CHANNEL_CODING 

	bitvec_write_field(dest, wp,0x1,1); // switch TIMING_ADVANCE_VALUE = on
	bitvec_write_field(dest, wp,0x0,6); // TIMING_ADVANCE_VALUE
	bitvec_write_field(dest, wp,0x0,1); // switch TIMING_ADVANCE_INDEX = off
	
	bitvec_write_field(dest, wp,0x0,1); // Frequency Parameters = off

	bitvec_write_field(dest, wp,0x1,2); // Dynamic Allocation = off
	
	bitvec_write_field(dest, wp,0x0,1); // Dynamic Allocation
	bitvec_write_field(dest, wp,0x0,1); // P0 = off
	
	bitvec_write_field(dest, wp,0x1,0); // USF_GRANULARITY
	bitvec_write_field(dest, wp,0x1,1); // switch TFI   : on
	bitvec_write_field(dest, wp,tfi,5);// TFI

	bitvec_write_field(dest, wp,0x0,1); //
	bitvec_write_field(dest, wp,0x0,1); // TBF Starting Time = off
	bitvec_write_field(dest, wp,0x0,1); // Timeslot Allocation
	
	bitvec_write_field(dest, wp,0x0,5); // USF_TN 0 - 4
	bitvec_write_field(dest, wp,0x1,1); // USF_TN 5
	bitvec_write_field(dest, wp,0x1,3); // USF_TN 5
	bitvec_write_field(dest, wp,0x0,2); // USF_TN 6 - 7
//	bitvec_write_field(dest, wp,0x0,1); // Measurement Mapping struct not present
}


// GSM 04.08 9.1.18 Immediate assignment
int write_immediate_assignment(bitvec * dest, uint8_t downlink, uint8_t ra, uint32_t fn,
								uint8_t ta, uint16_t arfcn, uint8_t ts, uint8_t tsc, uint8_t tfi = 0, uint8_t usf = 0, uint32_t tlli = 0)
{
	unsigned wp = 0;

	bitvec_write_field(dest, wp,0x0,4);  // Skip Indicator
	bitvec_write_field(dest, wp,0x6,4);  // Protocol Discriminator
	bitvec_write_field(dest, wp,0x3F,8); // Immediate Assignment Message Type

	// 10.5.2.25b Dedicated mode or TBF
	bitvec_write_field(dest, wp,0x0,1);      // spare
	bitvec_write_field(dest, wp,0x0,1);      // TMA : Two-message assignment: No meaning
	bitvec_write_field(dest, wp,downlink,1); // Downlink : Downlink assignment to mobile in packet idle mode
	bitvec_write_field(dest, wp,0x1,1);      // T/D : TBF or dedicated mode: this message assigns a Temporary Block Flow (TBF).

	bitvec_write_field(dest, wp,0x0,4); // Page Mode

	// GSM 04.08 10.5.2.25a Packet Channel Description
	bitvec_write_field(dest, wp,0x1,5);                               // Channel type
	bitvec_write_field(dest, wp,ts,3);     // TN
	bitvec_write_field(dest, wp,tsc,3);    // TSC
	bitvec_write_field(dest, wp,0x0,3);                               // non-hopping RF channel configuraion
	bitvec_write_field(dest, wp,arfcn,10); // ARFCN

	//10.5.2.30 Request Reference
	bitvec_write_field(dest, wp,ra,8);                    // RA
	bitvec_write_field(dest, wp,(fn / (26 * 51)) % 32,5); // T1'
	bitvec_write_field(dest, wp,fn % 51,6);               // T3
	bitvec_write_field(dest, wp,fn % 26,5);               // T2

	// 10.5.2.40 Timing Advance
	bitvec_write_field(dest, wp,0x0,2); // spare
	bitvec_write_field(dest, wp,ta,6);  // Timing Advance value

	// No mobile allocation in non-hopping systems.
	// A zero-length LV.  Just write L=0.
	bitvec_write_field(dest, wp,0,8);

	if (downlink)
	{
		// GSM 04.08 10.5.2.16 IA Rest Octets
		bitvec_write_field(dest, wp, 3, 2);   // "HH"
		bitvec_write_field(dest, wp, 1, 2);   // "01" Packet Downlink Assignment
		bitvec_write_field(dest, wp,tlli,32); // TLLI
		bitvec_write_field(dest, wp,0x1,1);   // switch TFI   : on
		bitvec_write_field(dest, wp,tfi,5);   // TFI
		bitvec_write_field(dest, wp,0x0,1);   // RLC acknowledged mode
		bitvec_write_field(dest, wp,0x0,1);   // ALPHA = present
		bitvec_write_field(dest, wp,0x0,5);   // GAMMA power control parameter
		bitvec_write_field(dest, wp,0x0,1);   // Polling Bit
		bitvec_write_field(dest, wp,0x1,1);   // TA_VALID ???
		bitvec_write_field(dest, wp,0x1,1);   // switch TIMING_ADVANCE_INDEX = on
		bitvec_write_field(dest, wp,0x0,4);   // TIMING_ADVANCE_INDEX
		bitvec_write_field(dest, wp,0x0,1);   // TBF Starting TIME present
		bitvec_write_field(dest, wp,0x0,1);   // P0 not present
		bitvec_write_field(dest, wp,0x1,1);   // P0 not present
		bitvec_write_field(dest, wp,0xb,4);
	}
	else
	{
		// GMS 04.08 10.5.2.37b 10.5.2.16
		bitvec_write_field(dest, wp, 3, 2);    // "HH"
		bitvec_write_field(dest, wp, 0, 2);    // "0" Packet Uplink Assignment
		bitvec_write_field(dest, wp, 1, 1);    // Block Allocation : Not Single Block Allocation
		bitvec_write_field(dest, wp, tfi, 5);  // TFI_ASSIGNMENT Temporary Flow Identity
		bitvec_write_field(dest, wp, 0, 1);    // POLLING
		bitvec_write_field(dest, wp, 0, 1);    // ALLOCATION_TYPE: dynamic
		bitvec_write_field(dest, wp, usf, 3);    // USF
		bitvec_write_field(dest, wp, 0, 1);    // USF_GRANULARITY
		bitvec_write_field(dest, wp, 0 , 1);   // "0" power control: Not Present
		bitvec_write_field(dest, wp, 0, 2);    // CHANNEL_CODING_COMMAND 
		bitvec_write_field(dest, wp, 0, 1);    // TLLI_BLOCK_CHANNEL_CODING
		bitvec_write_field(dest, wp, 1 , 1);   // "1" Alpha : Present
		bitvec_write_field(dest, wp, 0, 4);    // Alpha
		bitvec_write_field(dest, wp, 0, 5);    // Gamma
		bitvec_write_field(dest, wp, 0, 1);    // TIMING_ADVANCE_INDEX_FLAG
		bitvec_write_field(dest, wp, 0, 1);    // TBF_STARTING_TIME_FLAG
	}

	if (wp%8)
		return wp/8+1;
	else
		return wp/8;
}


void write_ia_rest_octets_downlink_assignment(bitvec * dest, uint8_t tfi, uint32_t tlli)
{
	// GSM 04.08 10.5.2.16
	unsigned wp = 0;
	bitvec_write_field(dest, wp, 3, 2);    // "HH"
	bitvec_write_field(dest, wp, 1, 2);    // "01" Packet Downlink Assignment
	bitvec_write_field(dest, wp,tlli,32); // TLLI
	bitvec_write_field(dest, wp,0x1,1);   // switch TFI   : on
	bitvec_write_field(dest, wp,tfi,5);   // TFI
	bitvec_write_field(dest, wp,0x0,1);   // RLC acknowledged mode
	bitvec_write_field(dest, wp,0x0,1);   // ALPHA = present
	bitvec_write_field(dest, wp,0x0,5);   // GAMMA power control parameter
	bitvec_write_field(dest, wp,0x0,1);   // Polling Bit
	bitvec_write_field(dest, wp,0x1,1);   // TA_VALID ???
	bitvec_write_field(dest, wp,0x1,1);   // switch TIMING_ADVANCE_INDEX = on
	bitvec_write_field(dest, wp,0x0,4);   // TIMING_ADVANCE_INDEX
	bitvec_write_field(dest, wp,0x0,1);   // TBF Starting TIME present
	bitvec_write_field(dest, wp,0x0,1);   // P0 not present
	bitvec_write_field(dest, wp,0x1,1);   // P0 not present
	bitvec_write_field(dest, wp,0xb,4);
}

#if 0
void gprs_rlcmac_tx_ul_ack(uint8_t tfi, uint32_t tlli, RlcMacUplinkDataBlock_t * ul_data_block)
{
	bitvec *packet_uplink_ack_vec = bitvec_alloc(23);
	bitvec_unhex(packet_uplink_ack_vec, "2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	write_packet_uplink_ack(packet_uplink_ack_vec, tfi, tlli, ul_data_block->CV, ul_data_block->BSN);
	LOGP(DRLCMAC, LOGL_NOTICE, "TX: [PCU -> BTS] TFI: %u TLLI: 0x%08x Packet Uplink Ack\n", tfi, tlli);
	RlcMacDownlink_t * packet_uplink_ack = (RlcMacDownlink_t *)malloc(sizeof(RlcMacDownlink_t));
	LOGP(DRLCMAC, LOGL_NOTICE, "+++++++++++++++++++++++++ TX : Packet Uplink Ack +++++++++++++++++++++++++\n");
	decode_gsm_rlcmac_downlink(packet_uplink_ack_vec, packet_uplink_ack);
	LOGPC(DRLCMAC, LOGL_NOTICE, "\n");
	LOGP(DRLCMAC, LOGL_NOTICE, "------------------------- TX : Packet Uplink Ack -------------------------\n");
	free(packet_uplink_ack);
	gprs_rlcmac_enqueue_block(packet_uplink_ack_vec, 23);
	bitvec_free(packet_uplink_ack_vec);
}

void gprs_rlcmac_data_block_parse(gprs_rlcmac_tbf* tbf, RlcMacUplinkDataBlock_t * ul_data_block)
{
	// 1. Count the number of octets in header and number of LLC PDU in uplink data block.
	unsigned data_block_hdr_len = 3; // uplink data block header length: 3 mandatory octets
	unsigned llc_pdu_num = 0; // number of LLC PDU in data block

	
	if (ul_data_block->E_1 == 0) // Extension octet follows immediately
	{
		unsigned i = -1;
		do
		{
			i++;
			data_block_hdr_len += 1;
			llc_pdu_num++;
			
			// Singular case, TS 44.060 10.4.14
			if (ul_data_block->LENGTH_INDICATOR[i] == 0)
			{
				break;
			}
			
			// New LLC PDU starts after the current LLC PDU and continues until
			// the end of the RLC information field, no more extension octets.
			if ((ul_data_block->M[i] == 1)&&(ul_data_block->E[i] == 1))
			{
				llc_pdu_num++;
			}
		} while(ul_data_block->E[i] == 0); // there is another extension octet, which delimits the new LLC PDU
	}
	else
	{
		llc_pdu_num++;
	}
	if(ul_data_block->TI == 1) // TLLI field is present
	{
		tbf->tlli = ul_data_block->TLLI;
		data_block_hdr_len += 4; // TLLI length : 4 octets
		if (ul_data_block->PI == 1) // PFI is present if TI field indicates presence of TLLI
		{
			data_block_hdr_len += 1; // PFI length : 1 octet
		}
	}
	
	// 2. Extract all LLC PDU from uplink data block and send them to SGSN.
	unsigned llc_pdu_len = 0;
	unsigned data_octet_num = 0;

	for (unsigned num = 0; num < llc_pdu_num; num ++)
	{
		if (ul_data_block->E_1 == 0) // Extension octet follows immediately
		{
			// Singular case, TS 44.060 10.4.14
			if (ul_data_block->LENGTH_INDICATOR[num] == 0)
			{
				llc_pdu_len = UL_RLC_DATA_BLOCK_LEN - data_block_hdr_len;
			}
			else
			{
				llc_pdu_len = ul_data_block->LENGTH_INDICATOR[num];
			}
		}
		else
		{
			llc_pdu_len = UL_RLC_DATA_BLOCK_LEN - data_block_hdr_len;
		}
		
		for (unsigned i = tbf->llc_index; i < tbf->llc_index + llc_pdu_len; i++)
		{
			tbf->llc_frame[i] = ul_data_block->RLC_DATA[data_octet_num];
			data_octet_num++;
		}
		tbf->llc_index += llc_pdu_len;
		
		if (ul_data_block->E_1 == 0) // Extension octet follows immediately
		{
			// New LLC PDU starts after the current LLC PDU 
			if (ul_data_block->M[num] == 1)
			{
				gprs_rlcmac_tx_ul_ud(tbf);
				tbf->llc_index = 0;
				// New LLC PDU continues until the end of the RLC information field, no more extension octets.
				if ((ul_data_block->E[num] == 1))
				{
					llc_pdu_len = UL_RLC_DATA_BLOCK_LEN - data_block_hdr_len - data_octet_num;
					for (unsigned i = tbf->llc_index; i < tbf->llc_index + llc_pdu_len; i++)
					{
						tbf->llc_frame[i] = ul_data_block->RLC_DATA[data_octet_num];
						data_octet_num++;
					}
					tbf->llc_index += llc_pdu_len;
					num++;
				}
			}
		}
	}
}

/* Received Uplink RLC data block. */
int gprs_rlcmac_rcv_data_block(bitvec *rlc_block)
{
	struct gprs_rlcmac_tbf *tbf;

	LOGP(DRLCMAC, LOGL_NOTICE, "RX: [PCU <- BTS] Uplink Data Block\n");
	RlcMacUplinkDataBlock_t * ul_data_block = (RlcMacUplinkDataBlock_t *)malloc(sizeof(RlcMacUplinkDataBlock_t));
	LOGP(DRLCMAC, LOGL_NOTICE, "+++++++++++++++++++++++++ RX : Uplink Data Block +++++++++++++++++++++++++\n");
	decode_gsm_rlcmac_uplink_data(rlc_block, ul_data_block);
	LOGP(DRLCMAC, LOGL_NOTICE, "------------------------- RX : Uplink Data Block -------------------------\n");
	tbf = tbf_by_tfi(ul_data_block->TFI);
	if (!tbf) {
		return 0;
	}

	if (ul_data_block->TI == 1)
	{
		tbf->tlli = ul_data_block->TLLI;
	}

	switch (tbf->state) {
	case GPRS_RLCMAC_WAIT_DATA_SEQ_START: 
		if (ul_data_block->BSN == 0) {
			tbf->llc_index = 0;
			gprs_rlcmac_data_block_parse(tbf, ul_data_block);
			gprs_rlcmac_tx_ul_ack(tbf->tfi, tbf->tlli, ul_data_block);
			if (ul_data_block->CV == 0) {
				// Recieved last Data Block in this sequence.
				tbf->state = GPRS_RLCMAC_WAIT_NEXT_DATA_SEQ;
				gprs_rlcmac_tx_ul_ud(tbf);
			} else {
				tbf->bsn = ul_data_block->BSN;
				tbf->state = GPRS_RLCMAC_WAIT_NEXT_DATA_BLOCK;
			}
		}
		break;
	case GPRS_RLCMAC_WAIT_NEXT_DATA_BLOCK:
		if (tbf->bsn == (ul_data_block->BSN - 1)) {
			gprs_rlcmac_data_block_parse(tbf, ul_data_block);
			gprs_rlcmac_tx_ul_ack(tbf->tfi, tbf->tlli, ul_data_block);
			if (ul_data_block->CV == 0) {
				// Recieved last Data Block in this sequence.
				tbf->state = GPRS_RLCMAC_WAIT_NEXT_DATA_SEQ;
				gprs_rlcmac_tx_ul_ud(tbf);
			} else {
				tbf->bsn = ul_data_block->BSN;
				tbf->state = GPRS_RLCMAC_WAIT_NEXT_DATA_BLOCK;
			}
		} else {
			// Recieved Data Block with unexpected BSN.
			// We should try to find nesessary Data Block. 
			tbf->state = GPRS_RLCMAC_WAIT_NEXT_DATA_BLOCK;
		}
		break;
	case GPRS_RLCMAC_WAIT_NEXT_DATA_SEQ:
		// Now we just ignore all Data Blocks and wait next Uplink TBF
		break;
	}

	free(ul_data_block);
	return 1;
}
#endif

/* Received Uplink RLC control block. */
int gprs_rlcmac_rcv_control_block(bitvec *rlc_block, uint32_t fn)
{
	uint8_t tfi = 0;
	uint32_t tlli = 0;
	struct gprs_rlcmac_tbf *tbf;
//	struct gprs_rlcmac_tbf *ul_tbf;

	RlcMacUplink_t * ul_control_block = (RlcMacUplink_t *)malloc(sizeof(RlcMacUplink_t));
	LOGP(DRLCMAC, LOGL_NOTICE, "+++++++++++++++++++++++++ RX : Uplink Control Block +++++++++++++++++++++++++\n");
	decode_gsm_rlcmac_uplink(rlc_block, ul_control_block);
	LOGPC(DRLCMAC, LOGL_NOTICE, "\n");
	LOGP(DRLCMAC, LOGL_NOTICE, "------------------------- RX : Uplink Control Block -------------------------\n");
	switch (ul_control_block->u.MESSAGE_TYPE) {
	case MT_PACKET_CONTROL_ACK:
		tlli = ul_control_block->u.Packet_Control_Acknowledgement.TLLI;
		tbf = tbf_by_tlli(tlli);
		if (!tbf) {
			LOGP(DRLCMAC, LOGL_NOTICE, "PACKET CONTROL ACK with "
				"unknown TLLI=0x%x\n", tlli);
			return 0;
		}
		if (tbf->poll_fn != fn) {
			LOGP(DRLCMAC, LOGL_NOTICE, "PACKET CONTROL ACK for "
				"TFI=%d received at FN=%d, but was requested "
				"for FN=%d\n", tbf->tfi, fn, tbf->poll_fn);
		} else {
			LOGP(DRLCMAC, LOGL_NOTICE, "PACKET CONTROL ACK received on FN=%d as expected\n", fn);
		}
		LOGP(DRLCMAC, LOGL_NOTICE, "RX: [PCU <- BTS] TFI: %u TLLI: 0x%08x Packet Control Ack\n", tbf->tfi, tbf->tlli);
		LOGP(DRLCMAC, LOGL_NOTICE, "TBF: [UPLINK] END TFI: %u TLLI: 0x%08x \n", tbf->tfi, tbf->tlli);
		tbf_free(tbf);
		break;
	case MT_PACKET_DOWNLINK_ACK_NACK:
		tfi = ul_control_block->u.Packet_Downlink_Ack_Nack.DOWNLINK_TFI;
		tbf = tbf_by_tfi(tfi);
		if (!tbf) {
			return 0;
		}
		LOGP(DRLCMAC, LOGL_NOTICE, "RX: [PCU <- BTS] TFI: %u TLLI: 0x%08x Packet Downlink Ack/Nack\n", tbf->tfi, tbf->tlli);
		tlli = tbf->tlli;
		LOGP(DRLCMAC, LOGL_NOTICE, "TBF: [DOWNLINK] END TFI: %u TLLI: 0x%08x \n", tbf->tfi, tbf->tlli);
		tbf_free(tbf);
		break;
	}
	free(ul_control_block);
	return 1;
}

int gprs_rlcmac_rcv_block(uint8_t *data, uint8_t len, uint32_t fn)
{
	unsigned payload = data[0] >> 6;
	bitvec *block;
	int rc = 0;

	switch (payload) {
	case GPRS_RLCMAC_DATA_BLOCK:
		rc = gprs_rlcmac_rcv_data_block_acknowledged(data, len);
		break;
	case GPRS_RLCMAC_CONTROL_BLOCK:
		block = bitvec_alloc(len);
		if (!block)
			return -ENOMEM;
		bitvec_unpack(block, data);
		rc = gprs_rlcmac_rcv_control_block(block, fn);
		bitvec_free(block);
		break;
	case GPRS_RLCMAC_CONTROL_BLOCK_OPT:
		LOGP(DRLCMAC, LOGL_NOTICE, "GPRS_RLCMAC_CONTROL_BLOCK_OPT block payload is not supported.\n");
	default:
		LOGP(DRLCMAC, LOGL_NOTICE, "Unknown RLCMAC block payload.\n");
		rc = -EINVAL;
	}

	return rc;
}

#if 0
int select_pdch(uint8_t *_trx, uint8_t *_ts)
{
	struct gprs_rlcmac_bts *bts = gprs_rlcmac_bts;
	uint8_t trx, ts;

	for (trx = 0; trx < 8; trx++) {
		for (ts = 0; ts < 8; ts++) {
			if (bts->trx[trx].pdch[ts].enable) {
				*_trx = trx;
				*_ts = ts;
				return 0;
			}
		}
	}

	return -EBUSY;
}
#endif

int gprs_rlcmac_rcv_rach(uint8_t ra, uint32_t Fn, int16_t qta)
{
	struct gprs_rlcmac_tbf *tbf;
	uint8_t trx, ts;
	int tfi, usf; /* must be signed */

	// Create new TBF
	tfi = tfi_alloc(&trx, &ts);
	if (tfi < 0) {
		LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH ressource\n");
		/* FIXME: send reject */
		return -EBUSY;
	}
	usf = find_free_usf(trx, ts);
	if (usf < 0) {
		LOGP(DRLCMAC, LOGL_NOTICE, "No PDCH ressource for USF\n");
		/* FIXME: send reject */
		return -EBUSY;
	}
	tbf = tbf_alloc(tfi, trx, ts);
	if (qta < 0)
		qta = 0;
	if (qta > 252)
		qta = 252;
	tbf->ta = qta >> 2;
	tbf->direction = GPRS_RLCMAC_UL_TBF;
	tbf->dir.ul.usf = usf;
	tbf->state = GPRS_RLCMAC_FLOW;
	tbf_timer_start(tbf, 3169, T3169);
	LOGP(DRLCMAC, LOGL_NOTICE, "TBF: [UPLINK] START TFI: %u\n", tbf->tfi);
	LOGP(DRLCMAC, LOGL_NOTICE, "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_NOTICE, "TX: [PCU -> BTS] TFI: %u Packet Immidiate Assignment\n", tbf->tfi);
	bitvec *immediate_assignment = bitvec_alloc(23);
	bitvec_unhex(immediate_assignment, "2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	int len = write_immediate_assignment(immediate_assignment, 0, ra, Fn, tbf->ta, tbf->arfcn, tbf->ts, tbf->tsc, tbf->tfi, usf);
	pcu_l1if_tx_agch(immediate_assignment, len);
	bitvec_free(immediate_assignment);

	return 0;
}

// Send RLC data to OpenBTS.
void gprs_rlcmac_tx_dl_data_block(uint32_t tlli, uint8_t tfi, uint8_t *pdu, int start_index, int end_index, uint8_t bsn, uint8_t fbi)
{
	int spare_len = 0;
	bitvec *data_block_vector = bitvec_alloc(BLOCK_LEN);
	bitvec_unhex(data_block_vector, "2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	RlcMacDownlinkDataBlock_t * data_block = (RlcMacDownlinkDataBlock_t *)malloc(sizeof(RlcMacDownlinkDataBlock_t));
	data_block->PAYLOAD_TYPE = 0;
	data_block->RRBP = 0;
	data_block->SP = 1;
	data_block->USF = 1;
	data_block->PR = 0;
	data_block->TFI = tfi;
	data_block->FBI = fbi;
	data_block->BSN = bsn;
	
	// Last RLC data block of current LLC PDU
	if (fbi == 1)
	{
		data_block->E_1 = 0;
		data_block->M[0] = 0;
		data_block->E[0] = 1;
		// Singular case, TS 44.060 10.4.14
		if ((end_index - start_index) == (BLOCK_LEN - 3))
		{
			data_block->FBI = 0;
			data_block->LENGTH_INDICATOR[0] = 0;
			spare_len =  0;
			end_index--;
		}
		else
		 {
			data_block->LENGTH_INDICATOR[0] = end_index-start_index;
			spare_len = BLOCK_LEN - 4 - data_block->LENGTH_INDICATOR[0];
		}
	}
	else
	{
		data_block->E_1 = 1; 
	}

	int data_oct_num = 0;  
	int i = 0;
	// Pack LLC PDU into RLC data field 
	for(i = start_index; i < end_index; i++) {
		data_block->RLC_DATA[data_oct_num] = pdu[i];
		data_oct_num++;
	}
	// Fill spare bits
	for(i = data_oct_num; i < data_oct_num + spare_len; i++) {
		data_block->RLC_DATA[i] = 0x2b;
	}
	LOGP(DRLCMAC, LOGL_NOTICE, "TX: [PCU -> BTS] Downlink Data Block\n");
	LOGP(DRLCMAC, LOGL_NOTICE, "+++++++++++++++++++++++++ TX : Downlink Data Block +++++++++++++++++++++++++\n");
	encode_gsm_rlcmac_downlink_data(data_block_vector, data_block);
	LOGP(DRLCMAC, LOGL_NOTICE, "------------------------- TX : Downlink Data Block -------------------------\n");
	free(data_block);
	gprs_rlcmac_enqueue_block(data_block_vector, BLOCK_LEN);
	bitvec_free(data_block_vector);
	
	// Singular case, TS 44.060 10.4.14
	if ((fbi == 1)&&((end_index + 1 - start_index) == (BLOCK_LEN - 3)))
	{
		gprs_rlcmac_tx_dl_data_block(tlli, tfi, pdu, end_index, end_index+1, bsn+1, fbi);
	}
}

int gprs_rlcmac_segment_llc_pdu(struct gprs_rlcmac_tbf *tbf)
{
	int fbi = 0;
	int bsn = 0;
	int num_blocks = 0; // number of RLC data blocks necessary for LLC PDU transmission 


	// LLC PDU fits into one RLC data block with optional LI field.
	if (tbf->llc_index < BLOCK_LEN - 4)
	{
		fbi = 1;
		gprs_rlcmac_tx_dl_data_block(tbf->tlli, tbf->tfi, tbf->llc_frame, 0, tbf->llc_index, bsn, fbi);
	}
	// Necessary several RLC data blocks for transmit LLC PDU.
	else
	{
		// length of RLC data field in block (no optional octets)
		int block_data_len = BLOCK_LEN - 3; 
		
		// number of blocks with 20 octets length RLC data field
		num_blocks = tbf->llc_index/block_data_len; 
		
		// rest of LLC PDU, which doesn't fit into data blocks with 20 octets RLC data field
		int rest_len = tbf->llc_index%BLOCK_DATA_LEN; 
		if (rest_len > 0)
		{
			// add one block for transmission rest of LLC PDU
			num_blocks++;
		}

		int start_index = 0;
		int end_index = 0;

		// Transmit all RLC data blocks of current LLC PDU to MS
		for (bsn = 0; bsn < num_blocks; bsn++)
		{
			if (bsn == num_blocks-1)
			{
				if (rest_len > 0)
				{
					block_data_len = rest_len;
				}
				fbi = 1;
			}
			end_index = start_index + block_data_len;
			gprs_rlcmac_tx_dl_data_block(tbf->tlli, tbf->tfi, tbf->llc_frame, start_index, end_index, bsn, fbi);
			start_index += block_data_len;
		}
	}

	return 0;
}

/* Send Uplink unit-data to SGSN. */
void gprs_rlcmac_tx_ul_ud(gprs_rlcmac_tbf *tbf)
{
	const uint8_t qos_profile = QOS_PROFILE;
	struct msgb *llc_pdu;
	unsigned msg_len = NS_HDR_LEN + BSSGP_HDR_LEN + tbf->llc_index;

	LOGP(DBSSGP, LOGL_NOTICE, "TX: [PCU -> SGSN ] TFI: %u TLLI: 0x%08x DataLen: %u", tbf->tfi, tbf->tlli, tbf->llc_index);
	//LOGP(DBSSGP, LOGL_NOTICE, " Data = ");
	//for (unsigned i = 0; i < tbf->llc_index; i++)
	//	LOGPC(DBSSGP, LOGL_NOTICE, "%02x ", tbf->llc_frame[i]);
	
	bctx->cell_id = CELL_ID;
	bctx->nsei = NSEI;
	bctx->ra_id.mnc = MNC;
	bctx->ra_id.mcc = MCC;
	bctx->ra_id.lac = PCU_LAC;
	bctx->ra_id.rac = PCU_RAC;
	bctx->bvci = BVCI;

	llc_pdu = msgb_alloc_headroom(msg_len, msg_len,"llc_pdu");
	msgb_tvlv_push(llc_pdu, BSSGP_IE_LLC_PDU, sizeof(uint8_t)*tbf->llc_index, tbf->llc_frame);
	bssgp_tx_ul_ud(bctx, tbf->tlli, &qos_profile, llc_pdu);
}

void gprs_rlcmac_downlink_assignment(gprs_rlcmac_tbf *tbf)
{
	LOGP(DRLCMAC, LOGL_NOTICE, "TX: [PCU -> BTS] TFI: %u TLLI: 0x%08x Immidiate Assignment (CCCH)\n", tbf->tfi, tbf->tlli);
	bitvec *immediate_assignment = bitvec_alloc(23);
	bitvec_unhex(immediate_assignment, "2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	int len = write_immediate_assignment(immediate_assignment, 1, 125, get_current_fn(), tbf->ta, tbf->arfcn, tbf->ts, tbf->tsc, tbf->tfi, 0, tbf->tlli);
	pcu_l1if_tx_agch(immediate_assignment, len);
	bitvec_free(immediate_assignment);
	tbf_gsm_timer_start(tbf, 0, 120);
}

void gprs_rlcmac_packet_downlink_assignment(gprs_rlcmac_tbf *tbf)
{
	LOGP(DRLCMAC, LOGL_NOTICE, "TX: [PCU -> BTS] TFI: %u TLLI: 0x%08x Packet DL Assignment\n", tbf->tfi, tbf->tlli);
	bitvec *packet_downlink_assignment_vec = bitvec_alloc(23);
	bitvec_unhex(packet_downlink_assignment_vec, "2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	write_packet_downlink_assignment(packet_downlink_assignment_vec, tbf->tfi, tbf->tlli, tbf->arfcn, tbf->ts, tbf->ta, tbf->tsc);
	RlcMacDownlink_t * packet_downlink_assignment = (RlcMacDownlink_t *)malloc(sizeof(RlcMacDownlink_t));
	LOGP(DRLCMAC, LOGL_NOTICE, "+++++++++++++++++++++++++ TX : Packet Downlink Assignment +++++++++++++++++++++++++\n");
	decode_gsm_rlcmac_downlink(packet_downlink_assignment_vec, packet_downlink_assignment);
	LOGPC(DRLCMAC, LOGL_NOTICE, "\n");
	LOGP(DRLCMAC, LOGL_NOTICE, "------------------------- TX : Packet Downlink Assignment -------------------------\n");
	free(packet_downlink_assignment);
	gprs_rlcmac_enqueue_block(packet_downlink_assignment_vec, 23);
	bitvec_free(packet_downlink_assignment_vec);
	tbf_gsm_timer_start(tbf, 0, 120);
}