src/tbf.h

/*
 * Copyright (C) 2013 by Holger Hans Peter Freyther
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#pragma once

#ifdef __cplusplus

#include "gprs_rlcmac.h"
#include "llc.h"
#include "rlc.h"
#include "cxx_linuxlist.h"
#include <gprs_debug.h>

#include <stdint.h>
extern "C" {
#include <osmocom/core/utils.h>
}

struct bssgp_bvc_ctx;
struct pcu_l1_meas;
class GprsMs;

/*
 * TBF instance
 */

#define T_ASS_AGCH_USEC 200000	/* waiting after IMM.ASS confirm */
#define T_ASS_PACCH_SEC 2	/* timeout for pacch assigment */
#define T_REJ_PACCH_USEC 2000	/* timeout for tbf reject for PRR*/

enum gprs_rlcmac_tbf_state {
	GPRS_RLCMAC_NULL = 0,	/* new created TBF */
	GPRS_RLCMAC_ASSIGN,	/* wait for downlink assignment */
	GPRS_RLCMAC_FLOW,	/* RLC/MAC flow, resource needed */
	GPRS_RLCMAC_FINISHED,	/* flow finished, wait for release */
	GPRS_RLCMAC_WAIT_RELEASE,/* wait for release or restart of DL TBF */
	GPRS_RLCMAC_RELEASING,	/* releasing, wait to free TBI/USF */
};

enum gprs_rlcmac_tbf_poll_type {
	GPRS_RLCMAC_POLL_UL_ASS,
	GPRS_RLCMAC_POLL_DL_ASS,
	GPRS_RLCMAC_POLL_UL_ACK,
	GPRS_RLCMAC_POLL_DL_ACK,
};

enum gprs_rlcmac_tbf_poll_state {
	GPRS_RLCMAC_POLL_NONE = 0,
	GPRS_RLCMAC_POLL_SCHED, /* a polling was scheduled */
};

enum gprs_rlcmac_tbf_dl_ass_state {
	GPRS_RLCMAC_DL_ASS_NONE = 0,
	GPRS_RLCMAC_DL_ASS_SEND_ASS, /* send downlink assignment on next RTS */
	GPRS_RLCMAC_DL_ASS_WAIT_ACK, /* wait for PACKET CONTROL ACK */
};

extern const struct value_string gprs_rlcmac_tbf_dl_ass_state_names[];

enum gprs_rlcmac_tbf_ul_ass_state {
	GPRS_RLCMAC_UL_ASS_NONE = 0,
	GPRS_RLCMAC_UL_ASS_SEND_ASS, /* send uplink assignment on next RTS */
	GPRS_RLCMAC_UL_ASS_SEND_ASS_REJ, /* send assignment reject next RTS */
	GPRS_RLCMAC_UL_ASS_WAIT_ACK, /* wait for PACKET CONTROL ACK */
};

extern const struct value_string gprs_rlcmac_tbf_ul_ass_state_names[];

enum gprs_rlcmac_tbf_ul_ack_state {
	GPRS_RLCMAC_UL_ACK_NONE = 0,
	GPRS_RLCMAC_UL_ACK_SEND_ACK, /* send acknowledge on next RTS */
	GPRS_RLCMAC_UL_ACK_WAIT_ACK, /* wait for PACKET CONTROL ACK */
};

enum gprs_rlcmac_tbf_direction {
	GPRS_RLCMAC_DL_TBF,
	GPRS_RLCMAC_UL_TBF
};

enum tbf_counters {
	TBF_CTR_RLC_NACKED,
};

enum tbf_gprs_counters {
	TBF_CTR_GPRS_DL_CS1,
	TBF_CTR_GPRS_DL_CS2,
	TBF_CTR_GPRS_DL_CS3,
	TBF_CTR_GPRS_DL_CS4,
};

enum tbf_egprs_counters {
	TBF_CTR_EGPRS_DL_MCS1,
	TBF_CTR_EGPRS_DL_MCS2,
	TBF_CTR_EGPRS_DL_MCS3,
	TBF_CTR_EGPRS_DL_MCS4,
	TBF_CTR_EGPRS_DL_MCS5,
	TBF_CTR_EGPRS_DL_MCS6,
	TBF_CTR_EGPRS_DL_MCS7,
	TBF_CTR_EGPRS_DL_MCS8,
	TBF_CTR_EGPRS_DL_MCS9,
};

enum tbf_gprs_ul_counters {
        TBF_CTR_GPRS_UL_CS1,
        TBF_CTR_GPRS_UL_CS2,
        TBF_CTR_GPRS_UL_CS3,
        TBF_CTR_GPRS_UL_CS4,
};

enum tbf_egprs_ul_counters {
        TBF_CTR_EGPRS_UL_MCS1,
        TBF_CTR_EGPRS_UL_MCS2,
        TBF_CTR_EGPRS_UL_MCS3,
        TBF_CTR_EGPRS_UL_MCS4,
        TBF_CTR_EGPRS_UL_MCS5,
        TBF_CTR_EGPRS_UL_MCS6,
        TBF_CTR_EGPRS_UL_MCS7,
        TBF_CTR_EGPRS_UL_MCS8,
        TBF_CTR_EGPRS_UL_MCS9,
};

#define LOGPTBF(tbf, level, fmt, args...) LOGP(DRLCMAC, level, "%s " fmt, tbf_name(tbf), ## args)
#define LOGPTBFUL(tbf, level, fmt, args...) LOGP(DRLCMACUL, level, "%s " fmt, tbf_name(tbf), ## args)
#define LOGPTBFDL(tbf, level, fmt, args...) LOGP(DRLCMACDL, level, "%s " fmt, tbf_name(tbf), ## args)

enum tbf_timers {
	/* internal assign/reject timer */
	T0,

	/* Wait for reuse of USF and TFI(s) after the MS uplink assignment for this TBF is invalid. */
	T3169,

	/* Wait for reuse of TFI(s) after sending of the last RLC Data Block on this TBF.
	   Wait for reuse of TFI(s) after sending the PACKET TBF RELEASE for an MBMS radio bearer. */
	T3191,

	/* Wait for reuse of TFI(s) after reception of the final PACKET DOWNLINK ACK/NACK from the
	   MS for this TBF. */
	T3193,

	/* Wait for reuse of TFI(s) when there is no response from the MS
	   (radio failure or cell change) for this TBF/MBMS radio bearer. */
	T3195,
	T_MAX
};

#define GPRS_RLCMAC_FLAG_CCCH		0 /* assignment on CCCH */
#define GPRS_RLCMAC_FLAG_PACCH		1 /* assignment on PACCH */
#define GPRS_RLCMAC_FLAG_UL_DATA	2 /* uplink data received */
#define GPRS_RLCMAC_FLAG_DL_ACK		3 /* downlink acknowledge received  */
#define GPRS_RLCMAC_FLAG_TO_UL_ACK	4
#define GPRS_RLCMAC_FLAG_TO_DL_ACK	5
#define GPRS_RLCMAC_FLAG_TO_UL_ASS	6
#define GPRS_RLCMAC_FLAG_TO_DL_ASS	7
#define GPRS_RLCMAC_FLAG_TO_MASK	0xf0 /* timeout bits */

#define T_START(tbf, t, sec, usec, r, f) tbf->t_start(t, sec, usec, r, f, __FILE__, __LINE__)

struct gprs_rlcmac_tbf {
	gprs_rlcmac_tbf(BTS *bts_, gprs_rlcmac_tbf_direction dir);

	static void free_all(struct gprs_rlcmac_trx *trx);
	static void free_all(struct gprs_rlcmac_pdch *pdch);

	bool state_is(enum gprs_rlcmac_tbf_state rhs) const;
	bool state_is_not(enum gprs_rlcmac_tbf_state rhs) const;
	void set_state(enum gprs_rlcmac_tbf_state new_state);
	bool check_n_clear(uint8_t state_flag);
	void set_assigned_on(uint8_t state_flag, bool check_ccch);
	const char *state_name() const;

	const char *name() const;

	struct msgb *create_dl_ass(uint32_t fn, uint8_t ts);
	struct msgb *create_ul_ass(uint32_t fn, uint8_t ts);
	struct msgb *create_packet_access_reject();

	GprsMs *ms() const;
	void set_ms(GprsMs *ms);

	gprs_rlc_window *window();

	uint8_t tsc() const;

	int rlcmac_diag();

	int update();
	void handle_timeout();
	void stop_timers(const char *reason);
	bool timers_pending(enum tbf_timers t);
	void t_stop(enum tbf_timers t, const char *reason);
	void t_start(enum tbf_timers t, uint32_t sec, uint32_t microsec, const char *reason, bool force,
		     const char *file, unsigned line);
	int establish_dl_tbf_on_pacch();

	int check_polling(uint32_t fn, uint8_t ts,
		uint32_t *poll_fn, unsigned int *rrbp);
	void set_polling(uint32_t poll_fn, uint8_t ts, enum gprs_rlcmac_tbf_poll_type t);
	void poll_timeout();

	/** tlli handling */
	uint32_t tlli() const;
	bool is_tlli_valid() const;

	/** MS updating */
	void update_ms(uint32_t tlli, enum gprs_rlcmac_tbf_direction);

	uint8_t tfi() const;
	bool is_tfi_assigned() const;

	const char *imsi() const;
	void assign_imsi(const char *imsi);
	uint8_t ta() const;
	void set_ta(uint8_t);
	uint8_t ms_class() const;
	void set_ms_class(uint8_t);
	GprsCodingScheme current_cs() const;
	size_t llc_queue_size() const;

	time_t created_ts() const;
	uint8_t dl_slots() const;
	uint8_t ul_slots() const;

	bool is_control_ts(uint8_t ts) const;

	/* EGPRS */
	bool is_egprs_enabled() const;
	void disable_egprs();

	/* attempt to make things a bit more fair */
	void rotate_in_list();

	LListHead<gprs_rlcmac_tbf>& ms_list() {return this->m_ms_list;}
	const LListHead<gprs_rlcmac_tbf>& ms_list() const {return this->m_ms_list;}

	LListHead<gprs_rlcmac_tbf>& list();
	const LListHead<gprs_rlcmac_tbf>& list() const;

	uint32_t state_flags;
	enum gprs_rlcmac_tbf_direction direction;
	struct gprs_rlcmac_trx *trx;
	uint8_t first_ts; /* first TS used by TBF */
	uint8_t first_common_ts; /* first TS that the phone can send and
		reveive simultaniously */
	uint8_t control_ts; /* timeslot control messages and polling */
	struct gprs_rlcmac_pdch *pdch[8]; /* list of PDCHs allocated to TBF */

	gprs_llc m_llc;

	enum gprs_rlcmac_tbf_dl_ass_state dl_ass_state;
	enum gprs_rlcmac_tbf_ul_ass_state ul_ass_state;
	enum gprs_rlcmac_tbf_ul_ack_state ul_ack_state;

	enum gprs_rlcmac_tbf_poll_state poll_state;
	uint32_t poll_fn; /* frame number to poll */
	uint8_t poll_ts; /* TS to poll */

	gprs_rlc m_rlc;
	
	uint8_t n3105;	/* N3105 counter */
	
	struct osmo_gsm_timer_list	gsm_timer;
	unsigned int fT; /* fTxxxx number */
	unsigned int num_fT_exp; /* number of consecutive fT expirations */

	struct Meas {
		struct timeval rssi_tv; /* timestamp for rssi calculation */
		int32_t rssi_sum; /* sum of rssi values */
		int rssi_num; /* number of rssi values added since rssi_tv */

		Meas();
	} meas;

	/* Remember if the tbf was in wait_release state when we want to
	 * schedule a new dl assignment */
	uint8_t was_releasing;

	/* Can/should we upgrade this tbf to use multiple slots? */
	uint8_t upgrade_to_multislot;

	/* store the BTS this TBF belongs to */
	BTS *bts;

	uint8_t m_n3101; /* N3101 counter */

	/*
	 * private fields. We can't make it private as it is breaking the
	 * llist macros.
	 */
	uint8_t m_tfi;
	time_t m_created_ts;

	struct rate_ctr_group *m_ctrs;

protected:
	gprs_rlcmac_bts *bts_data() const;
	void enable_egprs();
	int set_tlli_from_ul(uint32_t new_tlli);
	void merge_and_clear_ms(GprsMs *old_ms);

	gprs_llc_queue *llc_queue();
	const gprs_llc_queue *llc_queue() const;

	static const char *tbf_state_name[6];

	class GprsMs *m_ms;

	/* Fields to take the TA/MS class values if no MS is associated */
	uint8_t m_ta;
	uint8_t m_ms_class;

private:
	enum gprs_rlcmac_tbf_state state;
	LListHead<gprs_rlcmac_tbf> m_list;
	LListHead<gprs_rlcmac_tbf> m_ms_list;
	bool m_egprs_enabled;
	struct osmo_timer_list T[T_MAX];
	mutable char m_name_buf[60];
};


struct gprs_rlcmac_ul_tbf *tbf_alloc_ul(struct gprs_rlcmac_bts *bts,
	int8_t use_trx, uint8_t ms_class, uint8_t egprs_ms_class,
	uint32_t tlli, uint8_t ta, GprsMs *ms);

struct gprs_rlcmac_ul_tbf *tbf_alloc_ul_tbf(struct gprs_rlcmac_bts *bts,
	GprsMs *ms, int8_t use_trx,
	uint8_t ms_class, uint8_t egprs_ms_class, uint8_t single_slot);

struct gprs_rlcmac_dl_tbf *tbf_alloc_dl_tbf(struct gprs_rlcmac_bts *bts,
	GprsMs *ms, int8_t use_trx,
	uint8_t ms_class, uint8_t egprs_ms_class, uint8_t single_slot);

void tbf_free(struct gprs_rlcmac_tbf *tbf);

struct gprs_rlcmac_ul_tbf *handle_tbf_reject(struct gprs_rlcmac_bts *bts,
	GprsMs *ms, uint32_t tlli, uint8_t trx_no, uint8_t ts_no);

int tbf_assign_control_ts(struct gprs_rlcmac_tbf *tbf);

inline bool gprs_rlcmac_tbf::state_is(enum gprs_rlcmac_tbf_state rhs) const
{
	return state == rhs;
}

inline bool gprs_rlcmac_tbf::state_is_not(enum gprs_rlcmac_tbf_state rhs) const
{
	return state != rhs;
}

const char *tbf_name(gprs_rlcmac_tbf *tbf);

inline const char *gprs_rlcmac_tbf::state_name() const
{
	return tbf_state_name[state];
}

/* Set assignment state and corrsponding flags */
inline void gprs_rlcmac_tbf::set_assigned_on(uint8_t state_flag, bool check_ccch)
{
	set_state(GPRS_RLCMAC_ASSIGN);
	if (check_ccch) {
		if (!(state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH)))
			state_flags |= (1 << state_flag);
	} else
		state_flags |= (1 << state_flag);
}

inline void gprs_rlcmac_tbf::set_state(enum gprs_rlcmac_tbf_state new_state)
{
	LOGP(DRLCMAC, LOGL_DEBUG, "%s changes state from %s to %s\n",
		tbf_name(this),
		tbf_state_name[state], tbf_state_name[new_state]);
	state = new_state;
}

inline bool gprs_rlcmac_tbf::check_n_clear(uint8_t state_flag)
{
	if ((state_flags & (1 << state_flag))) {
		state_flags &= ~(1 << state_flag);
		return true;
	}

	return false;
}

inline LListHead<gprs_rlcmac_tbf>& gprs_rlcmac_tbf::list()
{
	return this->m_list;
}

inline const LListHead<gprs_rlcmac_tbf>& gprs_rlcmac_tbf::list() const
{
	return this->m_list;
}

inline GprsMs *gprs_rlcmac_tbf::ms() const
{
	return m_ms;
}

inline bool gprs_rlcmac_tbf::is_tlli_valid() const
{
	return tlli() != 0;
}

inline bool gprs_rlcmac_tbf::is_tfi_assigned() const
{
	/* The TBF is established or has been assigned by a IMM.ASS for
	 * download */
	return state > GPRS_RLCMAC_ASSIGN ||
		(direction == GPRS_RLCMAC_DL_TBF &&
		 state == GPRS_RLCMAC_ASSIGN &&
		 (state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH)));
}

inline uint8_t gprs_rlcmac_tbf::tfi() const
{
	return m_tfi;
}

inline time_t gprs_rlcmac_tbf::created_ts() const
{
	return m_created_ts;
}

inline bool gprs_rlcmac_tbf::is_egprs_enabled() const
{
	return m_egprs_enabled;
}

inline void gprs_rlcmac_tbf::enable_egprs()
{
	m_egprs_enabled = true;
}

inline void gprs_rlcmac_tbf::disable_egprs()
{
	m_egprs_enabled = false;
}

struct gprs_rlcmac_dl_tbf : public gprs_rlcmac_tbf {
	gprs_rlcmac_dl_tbf(BTS *bts);

	void cleanup();
	void enable_egprs();
	/* dispatch Unitdata.DL messages */
	static int handle(struct gprs_rlcmac_bts *bts,
		const uint32_t tlli, const uint32_t old_tlli,
		const char *imsi, const uint8_t ms_class,
		const uint8_t egprs_ms_class, const uint16_t delay_csec,
		const uint8_t *data, const uint16_t len);

	int append_data(const uint8_t ms_class,
			const uint16_t pdu_delay_csec,
			const uint8_t *data, const uint16_t len);

	int rcvd_dl_ack(bool final, uint8_t ssn, uint8_t *rbb);
	int rcvd_dl_ack(bool final_ack, unsigned first_bsn, struct bitvec *rbb);
	struct msgb *create_dl_acked_block(uint32_t fn, uint8_t ts);
	void trigger_ass(struct gprs_rlcmac_tbf *old_tbf);

	bool handle_ack_nack();
	void request_dl_ack();
	bool need_control_ts() const;
	bool have_data() const;
	int frames_since_last_poll(unsigned fn) const;
	int frames_since_last_drain(unsigned fn) const;
	bool keep_open(unsigned fn) const;
	int release();
	int abort();
	uint16_t window_size() const;
	void egprs_calc_window_size();
	void update_coding_scheme_counter_dl(const GprsCodingScheme cs);

	/* TODO: add the gettimeofday as parameter */
	struct msgb *llc_dequeue(bssgp_bvc_ctx *bctx);

	/* Please note that all variables here will be reset when changing
	 * from WAIT RELEASE back to FLOW state (re-use of TBF).
	 * All states that need reset must be in this struct, so this is why
	 * variables are in both (dl and ul) structs and not outside union.
	 */
	gprs_rlc_dl_window m_window;
	int32_t m_tx_counter; /* count all transmitted blocks */
	uint8_t m_wait_confirm; /* wait for CCCH IMM.ASS cnf */
	bool m_dl_ack_requested;
	int32_t m_last_dl_poll_fn;
	int32_t m_last_dl_drained_fn;

	struct BandWidth {
		struct timeval dl_bw_tv; /* timestamp for dl bw calculation */
		uint32_t dl_bw_octets; /* number of octets since bw_tv */
		uint32_t dl_throughput; /* throughput to be displayed in stats */

		struct timeval dl_loss_tv; /* timestamp for loss calculation */
		uint16_t dl_loss_lost; /* sum of lost packets */
		uint16_t dl_loss_received; /* sum of received packets */

		BandWidth();
	} m_bw;

	struct rate_ctr_group *m_dl_gprs_ctrs;
	struct rate_ctr_group *m_dl_egprs_ctrs;

protected:
	struct ana_result {
		unsigned received_packets;
		unsigned lost_packets;
		unsigned received_bytes;
		unsigned lost_bytes;
	};

	int take_next_bsn(uint32_t fn, int previous_bsn,
		bool *may_combine);
	bool restart_bsn_cycle();
	int create_new_bsn(const uint32_t fn, GprsCodingScheme cs);
	struct msgb *create_dl_acked_block(const uint32_t fn, const uint8_t ts,
					int index, int index2 = -1);
	int update_window(const uint8_t ssn, const uint8_t *rbb);
	int update_window(unsigned first_bsn, const struct bitvec *rbb);
	int maybe_start_new_window();
	bool dl_window_stalled() const;
	void reuse_tbf();
	void start_llc_timer();
	int analyse_errors(char *show_rbb, uint8_t ssn, ana_result *res);
	void schedule_next_frame();

	enum egprs_rlc_dl_reseg_bsn_state egprs_dl_get_data
		(int bsn, uint8_t **block_data);
	unsigned int get_egprs_dl_spb_status(int bsn);
	enum egprs_rlcmac_dl_spb get_egprs_dl_spb(int bsn);

	struct osmo_timer_list m_llc_timer;
};

struct gprs_rlcmac_ul_tbf : public gprs_rlcmac_tbf {
	gprs_rlcmac_ul_tbf(BTS *bts);

	struct msgb *create_ul_ack(uint32_t fn, uint8_t ts);
	bool ctrl_ack_to_toggle();
	bool handle_ctrl_ack();
	void enable_egprs();
	/* blocks were acked */
	int rcv_data_block_acknowledged(
		const struct gprs_rlc_data_info *rlc,
		uint8_t *data, struct pcu_l1_meas *meas);


	/* TODO: extract LLC class? */
	int assemble_forward_llc(const gprs_rlc_data *data);
	int snd_ul_ud();

	egprs_rlc_ul_reseg_bsn_state handle_egprs_ul_spb(
		const struct gprs_rlc_data_info *rlc,
		struct gprs_rlc_data *block,
		uint8_t *data, const uint8_t block_idx);

	egprs_rlc_ul_reseg_bsn_state handle_egprs_ul_first_seg(
		const struct gprs_rlc_data_info *rlc,
		struct gprs_rlc_data *block,
		uint8_t *data, const uint8_t block_idx);

	egprs_rlc_ul_reseg_bsn_state handle_egprs_ul_second_seg(
		const struct gprs_rlc_data_info *rlc,
		struct gprs_rlc_data *block,
		uint8_t *data, const uint8_t block_idx);

	void egprs_calc_ulwindow_size();
	uint16_t window_size() const;
	void update_coding_scheme_counter_ul(const GprsCodingScheme cs);

	/* Please note that all variables here will be reset when changing
	 * from WAIT RELEASE back to FLOW state (re-use of TBF).
	 * All states that need reset must be in this struct, so this is why
	 * variables are in both (dl and ul) structs and not outside union.
	 */
	gprs_rlc_ul_window m_window;
	int32_t m_rx_counter; /* count all received blocks */
	uint8_t m_n3103;	/* N3103 counter */
	uint8_t m_usf[8];	/* list USFs per PDCH (timeslot) */
	uint8_t m_contention_resolution_done; /* set after done */
	uint8_t m_final_ack_sent; /* set if we sent final ack */

	struct rate_ctr_group *m_ul_gprs_ctrs;
	struct rate_ctr_group *m_ul_egprs_ctrs;

protected:
	void maybe_schedule_uplink_acknack(const gprs_rlc_data_info *rlc);
};

#ifdef __cplusplus
extern "C" {
#endif
void update_tbf_ta(struct gprs_rlcmac_ul_tbf *tbf, int8_t ta_delta);
void set_tbf_ta(struct gprs_rlcmac_ul_tbf *tbf, uint8_t ta);
#ifdef __cplusplus
}
#endif

inline enum gprs_rlcmac_tbf_direction reverse(enum gprs_rlcmac_tbf_direction dir)
{
	return (enum gprs_rlcmac_tbf_direction)
		((int)GPRS_RLCMAC_UL_TBF - (int)dir + (int)GPRS_RLCMAC_DL_TBF);
}

inline uint16_t gprs_rlcmac_ul_tbf::window_size() const
{
	return m_window.ws();
}

inline uint16_t gprs_rlcmac_dl_tbf::window_size() const
{
	return m_window.ws();
}

inline void gprs_rlcmac_ul_tbf::enable_egprs()
{
	m_window.set_sns(RLC_EGPRS_SNS);
	gprs_rlcmac_tbf::enable_egprs();
}

inline void gprs_rlcmac_dl_tbf::enable_egprs()
{
	m_window.set_sns(RLC_EGPRS_SNS);
	gprs_rlcmac_tbf::enable_egprs();
}

inline gprs_rlcmac_ul_tbf *as_ul_tbf(gprs_rlcmac_tbf *tbf)
{
	if (tbf && tbf->direction == GPRS_RLCMAC_UL_TBF)
		return static_cast<gprs_rlcmac_ul_tbf *>(tbf);
	else
		return NULL;
}

inline gprs_rlcmac_dl_tbf *as_dl_tbf(gprs_rlcmac_tbf *tbf)
{
	if (tbf && tbf->direction == GPRS_RLCMAC_DL_TBF)
		return static_cast<gprs_rlcmac_dl_tbf *>(tbf);
	else
		return NULL;
}

inline gprs_rlc_window *gprs_rlcmac_tbf::window()
{
	switch (direction)
	{
	case GPRS_RLCMAC_UL_TBF: return &as_ul_tbf(this)->m_window;
	case GPRS_RLCMAC_DL_TBF: return &as_dl_tbf(this)->m_window;
	}
	return NULL;
}

#endif