Osmocom Packet control Unit (PCU): Network-side GPRS (RLC/MAC); BTS- or BSC-colocated https://osmocom.org/projects/osmopcu
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osmo-pcu/src/rlc.h

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/* rlc header descriptions
*
* 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.
*/
#pragma once
#ifdef __cplusplus
extern "C" {
#endif
#include "coding_scheme.h"
#include <osmocom/core/endian.h>
#ifdef __cplusplus
}
#endif
#include <stdint.h>
#include <string.h>
#define RLC_GPRS_SNS 128 /* GPRS, must be power of 2 */
#define RLC_GPRS_WS 64 /* max window size */
#define RLC_EGPRS_MIN_WS 64 /* min window size */
#define RLC_EGPRS_MAX_WS 1024 /* min window size */
#define RLC_EGPRS_SNS 2048 /* EGPRS, must be power of 2 */
#define RLC_EGPRS_MAX_BSN_DELTA 512
#define RLC_MAX_SNS RLC_EGPRS_SNS
#define RLC_MAX_WS RLC_EGPRS_MAX_WS
#define RLC_MAX_LEN 74 /* MCS-9 data unit */
struct gprs_rlcmac_bts;
/* The state of a BSN in the send/receive window */
enum gprs_rlc_ul_bsn_state {
GPRS_RLC_UL_BSN_INVALID,
GPRS_RLC_UL_BSN_RECEIVED,
GPRS_RLC_UL_BSN_MISSING,
GPRS_RLC_UL_BSN_MAX,
};
enum gprs_rlc_dl_bsn_state {
GPRS_RLC_DL_BSN_INVALID,
GPRS_RLC_DL_BSN_NACKED,
GPRS_RLC_DL_BSN_ACKED,
GPRS_RLC_DL_BSN_UNACKED,
GPRS_RLC_DL_BSN_RESEND,
GPRS_RLC_DL_BSN_MAX,
};
/*
* EGPRS resegment status information for UL
* When only first split block is received bsn state
* will be set to EGPRS_RESEG_FIRST_SEG_RXD and when
* only second segment is received the state will be
* set to EGPRS_RESEG_SECOND_SEG_RXD. When both Split
* blocks are received the state will be set to
* EGPRS_RESEG_DEFAULT
* The EGPRS resegmentation feature allows MS to retransmit
* RLC blocks of HeaderType1, HeaderType2 by segmenting
* them to 2 HeaderType3 blocks(Example MCS5 will be
* retransmitted as 2 MCS2 blocks). Table 10.4.8b.1 of 44.060
* explains the possible values of SPB in HeadrType3 for UL
* direction. When the MCS is changed at the PCU, PCU directs the
* changed MCS to MS by PUAN or UPLINK ASSIGNMENT message along
* with RESEGMENT flag, Then MS may decide to retransmit the
* blocks by resegmenting it based on Table 8.1.1.1 of 44.060.
* The retransmission MCS is calculated based on current MCS of
* the Block and demanded MCS by PCU. Section 10.3a.4.3 of 44.060
* shows the HeadrType3 with SPB field present in it
*/
enum egprs_rlc_ul_reseg_bsn_state {
EGPRS_RESEG_DEFAULT = 0,
EGPRS_RESEG_FIRST_SEG_RXD = 0x01,
EGPRS_RESEG_SECOND_SEG_RXD = 0x02,
EGPRS_RESEG_INVALID = 0x04
};
/*
* EGPRS resegment status information for DL
* When only first segment is sent, bsn state
* will be set to EGPRS_RESEG_FIRST_SEG_SENT and when
* second segment is sent the state will be
* set to EGPRS_RESEG_SECOND_SEG_SENT.
* EGPRS_RESEG_DL_INVALID is set to 8 considering there is a scope for
* 3rd segment according to Table 10.4.8b.2 of 44.060
* The EGPRS resegmentation feature allows PCU to retransmit
* RLC blocks of HeaderType1, HeaderType2 by segmenting
* them to 2 HeaderType3 blocks(Example MCS5 will be
* retransmitted as 2 MCS2 blocks). Table 10.4.8b.2 of 44.060
* explains the possible values of SPB in HeadrType3 for DL
* direction.The PCU decides to retransmit the
* blocks by resegmenting it based on Table 8.1.1.1 of 44.060.
* The retransmission MCS is calculated based on current MCS of
* the Block and demanded MCS by PCU. Section 10.3a.3.3 of 44.060
* shows the HeadrType3 with SPB field present in it
*/
enum egprs_rlc_dl_reseg_bsn_state {
EGPRS_RESEG_DL_DEFAULT = 0,
EGPRS_RESEG_FIRST_SEG_SENT = 0x01,
EGPRS_RESEG_SECOND_SEG_SENT = 0x02,
EGPRS_RESEG_DL_INVALID = 0x08
};
/* Table 10.4.8b.2 of 44.060 */
enum egprs_rlcmac_dl_spb {
EGPRS_RLCMAC_DL_NO_RETX = 0,
EGPRS_RLCMAC_DL_FIRST_SEG = 2,
EGPRS_RLCMAC_DL_SEC_SEG = 3,
};
/*
* Valid puncturing scheme values
* TS 44.060 10.4.8a.3.1, 10.4.8a.2.1, 10.4.8a.1.1
*/
enum egprs_puncturing_values {
EGPRS_PS_1,
EGPRS_PS_2,
EGPRS_PS_3,
EGPRS_PS_INVALID,
};
/*
* EGPRS_MAX_PS_NUM_2 is valid for MCS 1,2,5,6.
* And EGPRS_MAX_PS_NUM_3 is valid for MCS 3,4,7,8,9
* TS 44.060 10.4.8a.3.1, 10.4.8a.2.1, 10.4.8a.1.1
*/
enum egprs_puncturing_types {
EGPRS_MAX_PS_NUM_2 = 2,
EGPRS_MAX_PS_NUM_3,
EGPRS_MAX_PS_NUM_INVALID,
};
static inline uint16_t mod_sns_half()
{
return (RLC_MAX_SNS / 2) - 1;
}
struct gprs_rlc_data_block_info {
unsigned int data_len; /* EGPRS: N2, GPRS: N2-2, N-2 */
unsigned int bsn;
unsigned int ti;
unsigned int e;
unsigned int cv; /* FBI == 1 <=> CV == 0 */
unsigned int pi;
unsigned int spb;
};
struct gprs_rlc_data_info {
enum CodingScheme cs;
unsigned int r;
unsigned int si;
unsigned int tfi;
unsigned int cps;
unsigned int rsb;
unsigned int usf;
unsigned int es_p;
unsigned int rrbp;
unsigned int pr;
uint8_t num_data_blocks; /* this can actually be only 0, 1, 2: enforced in gprs_rlc_data_header_init() */
unsigned int with_padding;
unsigned int data_offs_bits[2];
struct gprs_rlc_data_block_info block_info[2];
};
/* holds the current status of the block w.r.t UL/DL split blocks */
union split_block_status {
egprs_rlc_ul_reseg_bsn_state block_status_ul;
egprs_rlc_dl_reseg_bsn_state block_status_dl;
};
struct gprs_rlc_data {
/* block data including LI headers */
uint8_t block[RLC_MAX_LEN];
/* block data len including LI headers*/
uint8_t len;
struct gprs_rlc_data_block_info block_info;
/*
* cs_current_trans is variable to hold the cs_last value for
* current transmission. cs_current_trans is same as cs_last during
* transmission case. during retransmission cs_current_trans is
* fetched from egprs_mcs_retx_tbl table based on
* cs and demanded cs.reference is 44.060 Table
* 8.1.1.1 and Table 8.1.1.2
* For UL. cs_last shall be used everywhere.
*/
enum CodingScheme cs_current_trans;
enum CodingScheme cs_last;
/*
* The MCS of initial transmission of a BSN
* This variable is used for split block
* processing in DL
*/
enum CodingScheme cs_init;
/* puncturing scheme value to be used for next transmission*/
enum egprs_puncturing_values next_ps;
/* holds the status of the block w.r.t UL/DL split blocks*/
union split_block_status spb_status;
};
uint8_t *prepare(struct gprs_rlc_data *rlc, size_t block_data_length);
void gprs_rlc_data_info_init_dl(struct gprs_rlc_data_info *rlc,
enum CodingScheme cs, bool with_padding, const unsigned int spb);
void gprs_rlc_data_info_init_ul(struct gprs_rlc_data_info *rlc,
enum CodingScheme cs, bool with_padding);
void gprs_rlc_data_block_info_init(struct gprs_rlc_data_block_info *rdbi,
enum CodingScheme cs, bool with_padding, const unsigned int spb);
unsigned int gprs_rlc_mcs_cps(enum CodingScheme cs, enum egprs_puncturing_values
punct, enum egprs_puncturing_values punct2, bool with_padding);
void gprs_rlc_mcs_cps_decode(unsigned int cps, enum CodingScheme cs,
int *punct, int *punct2, int *with_padding);
enum egprs_puncturing_values gprs_get_punct_scheme(enum egprs_puncturing_values
punct, const enum CodingScheme &cs,
const enum CodingScheme &cs_current_trans,
const enum egprs_rlcmac_dl_spb spb);
void gprs_update_punct_scheme(enum egprs_puncturing_values *punct,
const enum CodingScheme &cs);
/*
* I hold the currently transferred blocks and will provide
* the routines to manipulate these arrays.
*/
struct gprs_rlc {
void init();
gprs_rlc_data *block(int bsn);
gprs_rlc_data m_blocks[RLC_MAX_SNS/2];
};
/**
* TODO: for GPRS/EDGE maybe make sns a template parameter
* so we create specialized versions...
*/
struct gprs_rlc_v_b {
/* Check for an individual frame */
bool is_unacked(int bsn) const;
bool is_nacked(int bsn) const;
bool is_acked(int bsn) const;
bool is_resend(int bsn) const;
bool is_invalid(int bsn) const;
gprs_rlc_dl_bsn_state get_state(int bsn) const;
/* Mark a RLC frame for something */
void mark_unacked(int bsn);
void mark_nacked(int bsn);
void mark_acked(int bsn);
void mark_resend(int bsn);
void mark_invalid(int bsn);
void reset();
private:
bool is_state(int bsn, const gprs_rlc_dl_bsn_state state) const;
void mark(int bsn, const gprs_rlc_dl_bsn_state state);
gprs_rlc_dl_bsn_state m_v_b[RLC_MAX_SNS/2]; /* acknowledge state array */
};
/**
* TODO: The UL/DL code could/should share a base class.
*/
class gprs_rlc_window {
public:
gprs_rlc_window();
const uint16_t mod_sns() const;
const uint16_t mod_sns(uint16_t bsn) const;
const uint16_t sns() const;
const uint16_t ws() const;
void set_sns(uint16_t sns);
void set_ws(uint16_t ws);
protected:
uint16_t m_sns;
uint16_t m_ws;
};
struct gprs_rlc_dl_window: public gprs_rlc_window {
void reset();
bool window_stalled() const;
bool window_empty() const;
void increment_send();
void raise(int moves);
const uint16_t v_s() const;
const uint16_t v_s_mod(int offset) const;
const uint16_t v_a() const;
const uint16_t distance() const;
/* Methods to manage reception */
int resend_needed() const;
int mark_for_resend();
void update(struct gprs_rlcmac_bts *bts, char *show_rbb, uint16_t ssn,
uint16_t *lost, uint16_t *received);
void update(struct gprs_rlcmac_bts *bts, const struct bitvec *rbb,
uint16_t first_bsn, uint16_t *lost,
uint16_t *received);
int move_window();
void show_state(char *show_rbb);
int count_unacked();
uint16_t m_v_s; /* send state */
uint16_t m_v_a; /* ack state */
gprs_rlc_v_b m_v_b;
gprs_rlc_dl_window();
};
struct gprs_rlc_v_n {
void reset();
void mark_received(int bsn);
void mark_missing(int bsn);
bool is_received(int bsn) const;
gprs_rlc_ul_bsn_state state(int bsn) const;
private:
bool is_state(int bsn, const gprs_rlc_ul_bsn_state state) const;
void mark(int bsn, const gprs_rlc_ul_bsn_state state);
gprs_rlc_ul_bsn_state m_v_n[RLC_MAX_SNS/2]; /* receive state array */
};
struct gprs_rlc_ul_window: public gprs_rlc_window {
const uint16_t v_r() const;
const uint16_t v_q() const;
const void set_v_r(int);
const void set_v_q(int);
void reset_state();
const uint16_t ssn() const;
bool is_in_window(uint16_t bsn) const;
bool is_received(uint16_t bsn) const;
void update_rbb(char *rbb);
uint16_t update_egprs_rbb(uint8_t *rbb);
void raise_v_r_to(int moves);
void raise_v_r(const uint16_t bsn);
uint16_t raise_v_q();
void raise_v_q(int);
void receive_bsn(const uint16_t bsn);
bool invalidate_bsn(const uint16_t bsn);
uint16_t m_v_r; /* receive state */
uint16_t m_v_q; /* receive window state */
gprs_rlc_v_n m_v_n;
gprs_rlc_ul_window();
};
extern "C" {
/* TS 44.060 10.2.2 */
struct rlc_ul_header {
#if OSMO_IS_LITTLE_ENDIAN
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;
#elif OSMO_IS_BIG_ENDIAN
/* auto-generated from the little endian part above (libosmocore/contrib/struct_endianess.py) */
uint8_t pt:2, cv:4, si:1, r:1;
uint8_t spare:1, pi:1, tfi:5, ti:1;
uint8_t bsn:7, e:1;
#endif
} __attribute__ ((packed));
struct rlc_dl_header {
#if OSMO_IS_LITTLE_ENDIAN
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;
#elif OSMO_IS_BIG_ENDIAN
/* auto-generated from the little endian part above (libosmocore/contrib/struct_endianess.py) */
uint8_t pt:2, rrbp:2, s_p:1, usf:3;
uint8_t pr:2, tfi:5, fbi:1;
uint8_t bsn:7, e:1;
#endif
} __attribute__ ((packed));
struct rlc_li_field {
#if OSMO_IS_LITTLE_ENDIAN
uint8_t e:1,
m:1,
li:6;
#elif OSMO_IS_BIG_ENDIAN
/* auto-generated from the little endian part above (libosmocore/contrib/struct_endianess.py) */
uint8_t li:6, m:1, e:1;
#endif
} __attribute__ ((packed));
struct rlc_li_field_egprs {
#if OSMO_IS_LITTLE_ENDIAN
uint8_t e:1,
li:7;
#elif OSMO_IS_BIG_ENDIAN
/* auto-generated from the little endian part above (libosmocore/contrib/struct_endianess.py) */
uint8_t li:7, e:1;
#endif
} __attribute__ ((packed));
}
inline bool gprs_rlc_v_b::is_state(int bsn, const gprs_rlc_dl_bsn_state type) const
{
return m_v_b[bsn & mod_sns_half()] == type;
}
inline void gprs_rlc_v_b::mark(int bsn, const gprs_rlc_dl_bsn_state type)
{
m_v_b[bsn & mod_sns_half()] = type;
}
inline bool gprs_rlc_v_b::is_nacked(int bsn) const
{
return is_state(bsn, GPRS_RLC_DL_BSN_NACKED);
}
inline bool gprs_rlc_v_b::is_acked(int bsn) const
{
return is_state(bsn, GPRS_RLC_DL_BSN_ACKED);
}
inline bool gprs_rlc_v_b::is_unacked(int bsn) const
{
return is_state(bsn, GPRS_RLC_DL_BSN_UNACKED);
}
inline bool gprs_rlc_v_b::is_resend(int bsn) const
{
return is_state(bsn, GPRS_RLC_DL_BSN_RESEND);
}
inline bool gprs_rlc_v_b::is_invalid(int bsn) const
{
return is_state(bsn, GPRS_RLC_DL_BSN_INVALID);
}
inline gprs_rlc_dl_bsn_state gprs_rlc_v_b::get_state(int bsn) const
{
return m_v_b[bsn & mod_sns_half()];
}
inline void gprs_rlc_v_b::mark_resend(int bsn)
{
return mark(bsn, GPRS_RLC_DL_BSN_RESEND);
}
inline void gprs_rlc_v_b::mark_unacked(int bsn)
{
return mark(bsn, GPRS_RLC_DL_BSN_UNACKED);
}
inline void gprs_rlc_v_b::mark_acked(int bsn)
{
return mark(bsn, GPRS_RLC_DL_BSN_ACKED);
}
inline void gprs_rlc_v_b::mark_nacked(int bsn)
{
return mark(bsn, GPRS_RLC_DL_BSN_NACKED);
}
inline void gprs_rlc_v_b::mark_invalid(int bsn)
{
return mark(bsn, GPRS_RLC_DL_BSN_INVALID);
}
inline gprs_rlc_window::gprs_rlc_window()
: m_sns(RLC_GPRS_SNS)
, m_ws(RLC_GPRS_WS)
{
}
inline const uint16_t gprs_rlc_window::sns() const
{
return m_sns;
}
inline const uint16_t gprs_rlc_window::ws() const
{
return m_ws;
}
inline const uint16_t gprs_rlc_window::mod_sns() const
{
return sns() - 1;
}
inline const uint16_t gprs_rlc_window::mod_sns(uint16_t bsn) const
{
return bsn & mod_sns();
}
inline gprs_rlc_dl_window::gprs_rlc_dl_window()
: m_v_s(0)
, m_v_a(0)
{
reset();
}
inline const uint16_t gprs_rlc_dl_window::v_s() const
{
return m_v_s;
}
inline const uint16_t gprs_rlc_dl_window::v_s_mod(int offset) const
{
return mod_sns(m_v_s + offset);
}
inline const uint16_t gprs_rlc_dl_window::v_a() const
{
return m_v_a;
}
inline bool gprs_rlc_dl_window::window_stalled() const
{
return (mod_sns(m_v_s - m_v_a)) == ws();
}
inline bool gprs_rlc_dl_window::window_empty() const
{
return m_v_s == m_v_a;
}
inline void gprs_rlc_dl_window::increment_send()
{
m_v_s = (m_v_s + 1) & mod_sns();
}
inline void gprs_rlc_dl_window::raise(int moves)
{
m_v_a = (m_v_a + moves) & mod_sns();
}
inline const uint16_t gprs_rlc_dl_window::distance() const
{
return (m_v_s - m_v_a) & mod_sns();
}
inline gprs_rlc_ul_window::gprs_rlc_ul_window()
: m_v_r(0)
, m_v_q(0)
{
m_v_n.reset();
}
inline bool gprs_rlc_ul_window::is_in_window(uint16_t bsn) const
{
uint16_t offset_v_q;
/* current block relative to lowest unreceived block */
offset_v_q = (bsn - m_v_q) & mod_sns();
/* If out of window (may happen if blocks below V(Q) are received
* again. */
return offset_v_q < ws();
}
inline bool gprs_rlc_ul_window::is_received(uint16_t bsn) const
{
uint16_t offset_v_r;
/* Offset to the end of the received window */
offset_v_r = (m_v_r - 1 - bsn) & mod_sns();
return is_in_window(bsn) && m_v_n.is_received(bsn) && offset_v_r < ws();
}
inline void gprs_rlc_ul_window::reset_state()
{
m_v_r = 0;
m_v_q = 0;
}
inline const void gprs_rlc_ul_window::set_v_r(int v_r)
{
m_v_r = v_r;
}
inline const void gprs_rlc_ul_window::set_v_q(int v_q)
{
m_v_q = v_q;
}
inline const uint16_t gprs_rlc_ul_window::v_r() const
{
return m_v_r;
}
inline const uint16_t gprs_rlc_ul_window::v_q() const
{
return m_v_q;
}
inline const uint16_t gprs_rlc_ul_window::ssn() const
{
return m_v_r;
}
inline void gprs_rlc_ul_window::raise_v_r_to(int moves)
{
m_v_r = mod_sns(m_v_r + moves);
}
inline void gprs_rlc_ul_window::raise_v_q(int incr)
{
m_v_q = mod_sns(m_v_q + incr);
}
inline void gprs_rlc_v_n::mark_received(int bsn)
{
return mark(bsn, GPRS_RLC_UL_BSN_RECEIVED);
}
inline void gprs_rlc_v_n::mark_missing(int bsn)
{
return mark(bsn, GPRS_RLC_UL_BSN_MISSING);
}
inline bool gprs_rlc_v_n::is_received(int bsn) const
{
return is_state(bsn, GPRS_RLC_UL_BSN_RECEIVED);
}
inline bool gprs_rlc_v_n::is_state(int bsn, gprs_rlc_ul_bsn_state type) const
{
return m_v_n[bsn & mod_sns_half()] == type;
}
inline void gprs_rlc_v_n::mark(int bsn, gprs_rlc_ul_bsn_state type)
{
m_v_n[bsn & mod_sns_half()] = type;
}
inline gprs_rlc_ul_bsn_state gprs_rlc_v_n::state(int bsn) const
{
return m_v_n[bsn & mod_sns_half()];
}
inline void gprs_rlc::init()
{
memset(m_blocks, 0, sizeof(m_blocks));
}
inline gprs_rlc_data *gprs_rlc::block(int bsn)
{
return &m_blocks[bsn & mod_sns_half()];
}