Cedric Roux
3310f5c6b0
This commit introduces an alternative RLC implementation based on 36.322 version 8. AM and UM done, TM not done. See openair2/LAYER2/rlc_v2/TODO for missing parts.
286 lines
10 KiB
C
286 lines
10 KiB
C
/*
|
|
* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
|
|
* contributor license agreements. See the NOTICE file distributed with
|
|
* this work for additional information regarding copyright ownership.
|
|
* The OpenAirInterface Software Alliance licenses this file to You under
|
|
* the OAI Public License, Version 1.1 (the "License"); you may not use this file
|
|
* except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.openairinterface.org/?page_id=698
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*-------------------------------------------------------------------------------
|
|
* For more information about the OpenAirInterface (OAI) Software Alliance:
|
|
* contact@openairinterface.org
|
|
*/
|
|
|
|
#ifndef _RLC_ENTITY_AM_H_
|
|
#define _RLC_ENTITY_AM_H_
|
|
|
|
#include <stdint.h>
|
|
|
|
#include "rlc_entity.h"
|
|
#include "rlc_pdu.h"
|
|
#include "rlc_sdu.h"
|
|
|
|
/*
|
|
* Here comes some documentation to understand the reassembly
|
|
* logic in the code and the fields in the structure rlc_am_reassemble_t.
|
|
*
|
|
* Inside RLC, we deal with SDUs, PDUs and PDU segments.
|
|
* SDUs are packets coming from upper layer.
|
|
* A PDU is made of a header and a payload.
|
|
* In the payload there are SDUs.
|
|
* First SDU and last SDU in a PDU may be incomplete.
|
|
* PDU segments exist in case of retransmissions when the MAC
|
|
* layer asks for less data than previously, in which case
|
|
* only part of the previous PDU is sent.
|
|
*
|
|
* This is PDU data (just bytes):
|
|
* ---------------------------------------------------------
|
|
* | PDU data |
|
|
* ---------------------------------------------------------
|
|
* It contains SDUs, like:
|
|
* ---------------------------------------------------------
|
|
* | SDU 1 | SDU 2 | [...] | SDU n |
|
|
* ---------------------------------------------------------
|
|
* SDU 1 may be only the end of an SDU from which previous bytes were
|
|
* transmitted in previous PDUs.
|
|
* SDU n may be only the start of an SDU, that is more bytes from
|
|
* this SDU may be sent in successive PDUs.
|
|
*
|
|
* At front of the PDU data, we have a header:
|
|
* --------------- ---------------------------------------------------------
|
|
* | PDU header | | SDU 1 | SDU 2 | [...] | SDU n |
|
|
* --------------- ---------------------------------------------------------
|
|
* PDU header describes PDU data (most notably lengths).
|
|
*
|
|
* A PDU segment is a part of a PDU. For example, from this PDU data:
|
|
* ---------------------------------------------------------
|
|
* | SDU 1 | SDU 2 | [...] | SDU n |
|
|
* ---------------------------------------------------------
|
|
* We can extract the following PDU segment (data part only):
|
|
* ----------------------
|
|
* | PDU segment data |
|
|
* ----------------------
|
|
* This PDU segment would contain the end of SDU 2 above and some SDUs up to,
|
|
* let's say SDU x (x is 5 below).
|
|
*
|
|
* In front of a transmitted PDU segment, we have a header,
|
|
* containing the important variable 'so' (segment offset) that gives
|
|
* the index of the first byte of the segment in the original PDU.
|
|
* -------------- ----------------------
|
|
* | seg. header| | PDU segment data |
|
|
* -------------- ----------------------
|
|
*
|
|
* Let's now explain the data structure rlc_am_reassemble_t.
|
|
*
|
|
* In the structure rlc_am_reassemble_t, the fields fi, e, sn and so
|
|
* are coming from the PDU segment header and the semantics is the
|
|
* one of the RLC specs.
|
|
*
|
|
* The currently processed PDU segment is stored in 'start'.
|
|
* We have 'start->s->data_offset' and 'start->s->size'.
|
|
* start->s->data_offset is the index of the start of the data in the
|
|
* PDU segment. That is if the header is of length 3 bytes
|
|
* then start->s->data_offset is 3.
|
|
* start->s->size is the total length of the PDU segment,
|
|
* including header.
|
|
* The size of actual data bytes in the PDU segment is thus
|
|
* start->s->size - start->s->data_offset.
|
|
*
|
|
* The field sdu_len is the length of the current SDU being
|
|
* processed.
|
|
*
|
|
* The field sdu_offset is the starting point of the
|
|
* current SDU being processed (starting from beginning
|
|
* of PDU segment, including header).
|
|
*
|
|
* The field data_pos is the current read pointer. 0 points to
|
|
* the beginning of the PDU segment (including header).
|
|
*
|
|
* The field pdu_byte points to the current byte in the original
|
|
* PDU (not the PDU segment). It starts at 0 when we start
|
|
* processing a new PDU (when a new 'sn' is seen) and always
|
|
* increases after each byte processed. This is tha variable
|
|
* that is used to know if the next PDU segment will be used
|
|
* or not and if yes, starting from which data byte (see
|
|
* function rlc_am_reassemble_next_segment).
|
|
*
|
|
* 'so' is important and points to the byte in the original PDU
|
|
* that is the first byte of the PDU segment.
|
|
*
|
|
* For example, let's take this PDU segment data from above:
|
|
* ----------------------
|
|
* | PDU segment data |
|
|
* ----------------------
|
|
* Let's say it is decomposed as:
|
|
* ----------------------
|
|
* |222|33|4444|55555555|
|
|
* ----------------------
|
|
* It contains SDUs 2, 3, 4, and 5.
|
|
* SDU 2 is 3 bytes, SDU 3 is 2 bytes, SDU 4 is 4 bytes, SDU 5 is 8 bytes.
|
|
*
|
|
* Let's suppose that the original PDU starts with:
|
|
* ----------------
|
|
* |1111111|222222|
|
|
* ----------------
|
|
*
|
|
* (In this example, in the PDU segment, SDU 2 is not full,
|
|
* we only have its end.)
|
|
*
|
|
* Then 'so' is 13 (SDU 1 is 7 bytes, head of SDU 2 is 6 bytes).
|
|
*
|
|
* Let's continue with our PDU segment data.
|
|
* Let's say we are current processing SDU 4.
|
|
* Let's say the read pointer (variable 'data_pos') is there:
|
|
* ----------------------
|
|
* |222|33|4444|55555555|
|
|
* ----------------------
|
|
* ^
|
|
* read pointer (data_pos)
|
|
*
|
|
* Then:
|
|
* - sdu_len is 4
|
|
* - sdu_offset is 5 + [PDU segment header length]
|
|
* (it points to the beginning of SDU 4, starting
|
|
* from the head of the PDU segment, that is
|
|
* 3 bytes for SDU 2, 2 bytes for SDU 3, and the
|
|
* PDU segment header length)
|
|
* - start->s->data_offset is [PDU segment header length]
|
|
* - pdu_byte is 20
|
|
* (13 bytes from beginning of original PDU,
|
|
* 3 bytes for SDU 2, 2 bytes for SDU 3, then 2 bytes for SDU 4)
|
|
* - data_pos = read pointer = 7 + [PDU segment header length]
|
|
*
|
|
* To finish this description, in the code, a PDU is simply
|
|
* seen as a PDU segment with 'so' = 0 (and is_last == 1 (lsf in the specs),
|
|
* but this variable is not used by the reassembly logic).
|
|
*
|
|
* And for [PDU segment header length] we use start->s->data_offset.
|
|
*
|
|
* To recap, here is an illustration of the various variables
|
|
* and what starting point they use. In the figures, the start
|
|
* of the variable name is aligned to the byte it refers to.
|
|
* + is used to show the starting point.
|
|
*
|
|
* Let's put the PDU segment back into the original PDU.
|
|
* And let's show the values for when the read pointer
|
|
* is on the second byte of SDU 4 (as above).
|
|
*
|
|
* +++++++++++++++ so
|
|
* +++++++++++++++++++++++ pdu_byte
|
|
* ---------------------------------------------------------
|
|
* | SDU 1| SDU 2..222|33|4444|55555555| [...] | SDU n |
|
|
* ---------------------------------------------------------
|
|
*
|
|
* And now the PDU segment with header.
|
|
*
|
|
*
|
|
* ++++ sdu_len
|
|
* ++++++++++++++++++++++ sdu_offset
|
|
* +++++++++++++++++++++++ data_pos
|
|
* +++++++++++++++ start->s->data_offset
|
|
* +++++++++++++++++++++++++++++++++++++ start->s->size
|
|
* -------------- ----------------------
|
|
* | seg. header| |222|33|4444|55555555|
|
|
* -------------- ----------------------
|
|
*
|
|
* We see three case for the starting point:
|
|
* - start of original PDU (without any header)
|
|
* - start of header of current PDU segment
|
|
* - start of current SDU (for sdu_len)
|
|
*/
|
|
|
|
typedef struct {
|
|
rlc_rx_pdu_segment_t *start; /* start of list */
|
|
rlc_rx_pdu_segment_t *end; /* end of list (last element) */
|
|
int pos; /* byte to get from current buffer */
|
|
char sdu[SDU_MAX]; /* sdu is reassembled here */
|
|
int sdu_pos; /* next byte to put in sdu */
|
|
|
|
/* decoder of current PDU */
|
|
rlc_pdu_decoder_t dec;
|
|
int fi;
|
|
int e;
|
|
int sn;
|
|
int so;
|
|
int sdu_len;
|
|
int sdu_offset;
|
|
int data_pos;
|
|
int pdu_byte;
|
|
} rlc_am_reassemble_t;
|
|
|
|
typedef struct {
|
|
rlc_entity_t common;
|
|
|
|
/* configuration */
|
|
int t_reordering;
|
|
int t_status_prohibit;
|
|
int t_poll_retransmit;
|
|
int poll_pdu; /* -1 means infinity */
|
|
int poll_byte; /* -1 means infinity */
|
|
int max_retx_threshold;
|
|
|
|
/* runtime rx */
|
|
int vr_r;
|
|
int vr_x;
|
|
int vr_ms;
|
|
int vr_h;
|
|
|
|
int status_triggered;
|
|
|
|
/* runtime tx */
|
|
int vt_a;
|
|
int vt_s;
|
|
int poll_sn;
|
|
int pdu_without_poll;
|
|
int byte_without_poll;
|
|
int force_poll;
|
|
|
|
/* set to the latest know time by the user of the module. Unit: ms */
|
|
uint64_t t_current;
|
|
|
|
/* timers (stores the TTI of activation, 0 means not active) */
|
|
uint64_t t_reordering_start;
|
|
uint64_t t_status_prohibit_start;
|
|
uint64_t t_poll_retransmit_start;
|
|
|
|
/* rx management */
|
|
rlc_rx_pdu_segment_t *rx_list;
|
|
int rx_size;
|
|
int rx_maxsize;
|
|
|
|
/* reassembly management */
|
|
rlc_am_reassemble_t reassemble;
|
|
|
|
/* tx management */
|
|
rlc_sdu_t *tx_list;
|
|
rlc_sdu_t *tx_end;
|
|
int tx_size;
|
|
int tx_maxsize;
|
|
|
|
rlc_tx_pdu_segment_t *wait_list;
|
|
rlc_tx_pdu_segment_t *retransmit_list;
|
|
|
|
rlc_tx_pdu_segment_t *ack_list;
|
|
} rlc_entity_am_t;
|
|
|
|
void rlc_entity_am_recv_sdu(rlc_entity_t *entity, char *buffer, int size,
|
|
int sdu_id);
|
|
void rlc_entity_am_recv_pdu(rlc_entity_t *entity, char *buffer, int size);
|
|
rlc_entity_buffer_status_t rlc_entity_am_buffer_status(
|
|
rlc_entity_t *entity, int maxsize);
|
|
int rlc_entity_am_generate_pdu(rlc_entity_t *entity, char *buffer, int size);
|
|
void rlc_entity_am_set_time(rlc_entity_t *entity, uint64_t now);
|
|
void rlc_entity_am_discard_sdu(rlc_entity_t *entity, int sdu_id);
|
|
void rlc_entity_am_reestablishment(rlc_entity_t *entity);
|
|
void rlc_entity_am_delete(rlc_entity_t *entity);
|
|
|
|
#endif /* _RLC_ENTITY_AM_H_ */
|