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480 lines
15 KiB
C++
480 lines
15 KiB
C++
/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2020 Software Radio Systems Limited
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*
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* By using this file, you agree to the terms and conditions set
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* forth in the LICENSE file which can be found at the top level of
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* the distribution.
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*
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*/
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#ifndef SRSLTE_RLC_AM_LTE_H
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#define SRSLTE_RLC_AM_LTE_H
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#include "srslte/adt/accumulators.h"
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#include "srslte/adt/circular_array.h"
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#include "srslte/common/buffer_pool.h"
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#include "srslte/common/common.h"
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#include "srslte/common/task_scheduler.h"
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#include "srslte/common/timeout.h"
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#include "srslte/interfaces/pdcp_interface_types.h"
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#include "srslte/upper/byte_buffer_queue.h"
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#include "srslte/upper/rlc_am_base.h"
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#include "srslte/upper/rlc_common.h"
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#include <deque>
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#include <list>
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#include <map>
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namespace srslte {
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#undef RLC_AM_BUFFER_DEBUG
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struct rlc_amd_rx_pdu_t {
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rlc_amd_pdu_header_t header;
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unique_byte_buffer_t buf;
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uint32_t rlc_sn;
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};
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struct rlc_amd_rx_pdu_segments_t {
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std::list<rlc_amd_rx_pdu_t> segments;
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};
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struct rlc_amd_tx_pdu_t {
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rlc_amd_pdu_header_t header;
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unique_byte_buffer_t buf;
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pdcp_sn_vector_t pdcp_sns;
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uint32_t retx_count;
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uint32_t rlc_sn;
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bool is_acked;
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};
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struct rlc_amd_retx_t {
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uint32_t sn;
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bool is_segment;
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uint32_t so_start;
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uint32_t so_end;
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};
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struct rlc_sn_info_t {
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uint32_t sn;
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bool is_acked;
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};
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struct pdcp_sdu_info_t {
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uint32_t sn;
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bool fully_txed; // Boolean indicating if the SDU is fully transmitted.
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bool fully_acked; // Boolean indicating if the SDU is fully acked. This is only necessary temporarely to avoid
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// duplicate removal from the queue while processing the status report
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std::vector<rlc_sn_info_t> rlc_sn_info_list; // List of RLC PDUs in transit and whether they have been acked or not.
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};
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template <class T>
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struct rlc_ringbuffer_t {
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rlc_ringbuffer_t() { clear(); }
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T& add_pdu(size_t sn)
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{
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assert(not has_sn(sn));
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window[sn].rlc_sn = sn;
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active_flag[sn] = true;
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count++;
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return window[sn];
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}
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void remove_pdu(size_t sn)
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{
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assert(active_flag[sn]);
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window[sn] = {};
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active_flag[sn] = false;
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count--;
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}
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T& operator[](size_t sn)
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{
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assert(has_sn(sn));
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return window[sn];
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}
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size_t size() const { return count; }
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bool empty() const { return count == 0; }
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void clear()
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{
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std::fill(active_flag.begin(), active_flag.end(), false);
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count = 0;
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}
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bool has_sn(uint32_t sn) const { return active_flag[sn] and (window[sn].rlc_sn == sn); }
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// Return the sum data bytes of all active PDUs (check PDU is non-null)
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uint32_t get_buffered_bytes()
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{
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uint32_t buff_size = 0;
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for (const auto& pdu : window) {
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if (pdu.buf != nullptr) {
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buff_size += pdu.buf->N_bytes;
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}
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}
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return buff_size;
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}
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private:
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size_t count = 0;
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srslte::circular_array<bool, RLC_AM_WINDOW_SIZE> active_flag = {};
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srslte::circular_array<T, RLC_AM_WINDOW_SIZE> window;
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};
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struct buffered_pdcp_pdu_list {
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public:
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explicit buffered_pdcp_pdu_list();
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void clear();
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void add_pdcp_sdu(uint32_t sn)
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{
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assert(not has_pdcp_sn(sn));
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buffered_pdus[get_idx(sn)].sn = sn;
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count++;
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}
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void clear_pdcp_sdu(uint32_t sn)
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{
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uint32_t sn_idx = get_idx(sn);
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buffered_pdus[sn_idx].sn = invalid_sn;
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buffered_pdus[sn_idx].fully_acked = false;
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buffered_pdus[sn_idx].fully_txed = false;
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buffered_pdus[sn_idx].rlc_sn_info_list.clear();
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count--;
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}
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pdcp_sdu_info_t& operator[](uint32_t sn)
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{
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assert(has_pdcp_sn(sn));
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return buffered_pdus[get_idx(sn)];
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}
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bool has_pdcp_sn(uint32_t pdcp_sn) const
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{
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assert(pdcp_sn <= max_pdcp_sn or pdcp_sn == status_report_sn);
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return buffered_pdus[get_idx(pdcp_sn)].sn == pdcp_sn;
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}
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uint32_t nof_sdus() const { return count; }
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private:
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const static size_t max_pdcp_sn = 262143u;
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const static size_t max_buffer_idx = 4096u;
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const static uint32_t status_report_sn = std::numeric_limits<uint32_t>::max();
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const static uint32_t invalid_sn = std::numeric_limits<uint32_t>::max() - 1;
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size_t get_idx(uint32_t sn) const
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{
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return (sn != status_report_sn) ? static_cast<size_t>(sn % max_buffer_idx) : max_buffer_idx;
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}
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// size equal to buffer_size + 1 (last element for Status Report)
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std::vector<pdcp_sdu_info_t> buffered_pdus;
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uint32_t count = 0;
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};
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class pdu_retx_queue
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{
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public:
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rlc_amd_retx_t& push()
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{
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assert(not full());
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rlc_amd_retx_t& p = buffer[wpos];
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wpos = (wpos + 1) % RLC_AM_WINDOW_SIZE;
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return p;
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}
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void pop() { rpos = (rpos + 1) % RLC_AM_WINDOW_SIZE; }
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rlc_amd_retx_t& front()
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{
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assert(not empty());
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return buffer[rpos];
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}
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void clear()
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{
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wpos = 0;
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rpos = 0;
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}
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bool has_sn(uint32_t sn) const
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{
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for (size_t i = rpos; i != wpos; i = (i + 1) % RLC_AM_WINDOW_SIZE) {
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if (buffer[i].sn == sn) {
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return true;
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}
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}
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return false;
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}
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size_t size() const { return (wpos >= rpos) ? wpos - rpos : RLC_AM_WINDOW_SIZE + wpos - rpos; }
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bool empty() const { return wpos == rpos; }
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bool full() const { return size() == RLC_AM_WINDOW_SIZE - 1; }
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private:
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std::array<rlc_amd_retx_t, RLC_AM_WINDOW_SIZE> buffer;
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size_t wpos = 0;
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size_t rpos = 0;
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};
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class rlc_am_lte : public rlc_common
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{
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public:
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rlc_am_lte(srslog::basic_logger& logger,
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uint32_t lcid_,
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srsue::pdcp_interface_rlc* pdcp_,
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srsue::rrc_interface_rlc* rrc_,
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srslte::timer_handler* timers_);
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bool configure(const rlc_config_t& cfg_);
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void reestablish();
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void stop();
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void empty_queue();
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rlc_mode_t get_mode();
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uint32_t get_bearer();
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// PDCP interface
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void write_sdu(unique_byte_buffer_t sdu);
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void discard_sdu(uint32_t pdcp_sn);
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bool sdu_queue_is_full();
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// MAC interface
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bool has_data();
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uint32_t get_buffer_state();
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int read_pdu(uint8_t* payload, uint32_t nof_bytes);
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void write_pdu(uint8_t* payload, uint32_t nof_bytes);
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rlc_bearer_metrics_t get_metrics();
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void reset_metrics();
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void set_bsr_callback(bsr_callback_t callback);
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private:
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// Transmitter sub-class
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class rlc_am_lte_tx : public timer_callback
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{
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public:
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rlc_am_lte_tx(rlc_am_lte* parent_);
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~rlc_am_lte_tx();
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bool configure(const rlc_config_t& cfg_);
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void empty_queue();
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void reestablish();
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void stop();
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int write_sdu(unique_byte_buffer_t sdu);
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int read_pdu(uint8_t* payload, uint32_t nof_bytes);
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void discard_sdu(uint32_t discard_sn);
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bool sdu_queue_is_full();
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bool has_data();
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uint32_t get_buffer_state();
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// Timeout callback interface
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void timer_expired(uint32_t timeout_id);
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// Interface for Rx subclass
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void handle_control_pdu(uint8_t* payload, uint32_t nof_bytes);
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void set_bsr_callback(bsr_callback_t callback);
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private:
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int build_status_pdu(uint8_t* payload, uint32_t nof_bytes);
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int build_retx_pdu(uint8_t* payload, uint32_t nof_bytes);
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int build_segment(uint8_t* payload, uint32_t nof_bytes, rlc_amd_retx_t retx);
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int build_data_pdu(uint8_t* payload, uint32_t nof_bytes);
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void update_notification_ack_info(const rlc_amd_tx_pdu_t& tx_pdu);
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void debug_state();
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int required_buffer_size(rlc_amd_retx_t retx);
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void retransmit_pdu();
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// Helpers
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bool poll_required();
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bool do_status();
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void check_sn_reached_max_retx(uint32_t sn);
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rlc_am_lte* parent = nullptr;
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byte_buffer_pool* pool = nullptr;
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srslog::basic_logger& logger;
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/****************************************************************************
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* Configurable parameters
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* Ref: 3GPP TS 36.322 v10.0.0 Section 7
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***************************************************************************/
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rlc_am_config_t cfg = {};
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// TX SDU buffers
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byte_buffer_queue tx_sdu_queue;
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unique_byte_buffer_t tx_sdu;
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bool tx_enabled = false;
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/****************************************************************************
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* State variables and counters
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* Ref: 3GPP TS 36.322 v10.0.0 Section 7
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***************************************************************************/
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// Tx state variables
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uint32_t vt_a = 0; // ACK state. SN of next PDU in sequence to be ACKed. Low edge of tx window.
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uint32_t vt_ms = RLC_AM_WINDOW_SIZE; // Max send state. High edge of tx window. vt_a + window_size.
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uint32_t vt_s = 0; // Send state. SN to be assigned for next PDU.
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uint32_t poll_sn = 0; // Poll send state. SN of most recent PDU txed with poll bit set.
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// Tx counters
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uint32_t pdu_without_poll = 0;
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uint32_t byte_without_poll = 0;
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rlc_status_pdu_t tx_status;
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/****************************************************************************
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* Timers
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* Ref: 3GPP TS 36.322 v10.0.0 Section 7
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***************************************************************************/
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srslte::timer_handler::unique_timer poll_retx_timer;
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srslte::timer_handler::unique_timer status_prohibit_timer;
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// SDU info for PDCP notifications
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buffered_pdcp_pdu_list undelivered_sdu_info_queue;
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// Callback function for buffer status report
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bsr_callback_t bsr_callback;
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// Tx windows
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rlc_ringbuffer_t<rlc_amd_tx_pdu_t> tx_window;
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pdu_retx_queue retx_queue;
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pdcp_sn_vector_t notify_info_vec;
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// Mutexes
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std::mutex mutex;
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};
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// Receiver sub-class
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class rlc_am_lte_rx : public timer_callback
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{
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public:
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rlc_am_lte_rx(rlc_am_lte* parent_);
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~rlc_am_lte_rx();
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bool configure(rlc_am_config_t cfg_);
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void reestablish();
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void stop();
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void write_pdu(uint8_t* payload, uint32_t nof_bytes);
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uint32_t get_rx_buffered_bytes(); // returns sum of PDUs in rx_window
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uint32_t get_sdu_rx_latency_ms();
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// Timeout callback interface
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void timer_expired(uint32_t timeout_id);
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// Functions needed by Tx subclass to query rx state
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int get_status_pdu_length();
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int get_status_pdu(rlc_status_pdu_t* status, const uint32_t nof_bytes);
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bool get_do_status();
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void reset_status(); // called when status PDU has been sent
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private:
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void handle_data_pdu(uint8_t* payload, uint32_t nof_bytes, rlc_amd_pdu_header_t& header);
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void handle_data_pdu_segment(uint8_t* payload, uint32_t nof_bytes, rlc_amd_pdu_header_t& header);
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void reassemble_rx_sdus();
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bool inside_rx_window(const int16_t sn);
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void debug_state();
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void print_rx_segments();
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bool add_segment_and_check(rlc_amd_rx_pdu_segments_t* pdu, rlc_amd_rx_pdu_t* segment);
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rlc_am_lte* parent = nullptr;
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byte_buffer_pool* pool = nullptr;
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srslog::basic_logger& logger;
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/****************************************************************************
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* Configurable parameters
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* Ref: 3GPP TS 36.322 v10.0.0 Section 7
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***************************************************************************/
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rlc_am_config_t cfg = {};
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// RX SDU buffers
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unique_byte_buffer_t rx_sdu;
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/****************************************************************************
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* State variables and counters
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* Ref: 3GPP TS 36.322 v10.0.0 Section 7
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***************************************************************************/
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// Rx state variables
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uint32_t vr_r = 0; // Receive state. SN following last in-sequence received PDU. Low edge of rx window
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uint32_t vr_mr = RLC_AM_WINDOW_SIZE; // Max acceptable receive state. High edge of rx window. vr_r + window size.
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uint32_t vr_x = 0; // t_reordering state. SN following PDU which triggered t_reordering.
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uint32_t vr_ms = 0; // Max status tx state. Highest possible value of SN for ACK_SN in status PDU.
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uint32_t vr_h = 0; // Highest rx state. SN following PDU with highest SN among rxed PDUs.
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// Mutex to protect members
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std::mutex mutex;
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// Rx windows
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rlc_ringbuffer_t<rlc_amd_rx_pdu_t> rx_window;
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std::map<uint32_t, rlc_amd_rx_pdu_segments_t> rx_segments;
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bool poll_received = false;
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bool do_status = false;
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/****************************************************************************
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* Timers
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* Ref: 3GPP TS 36.322 v10.0.0 Section 7
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***************************************************************************/
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srslte::timer_handler::unique_timer reordering_timer;
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srslte::rolling_average<double> sdu_rx_latency_ms;
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};
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// Common variables needed/provided by parent class
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srsue::rrc_interface_rlc* rrc = nullptr;
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srslog::basic_logger& logger;
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srsue::pdcp_interface_rlc* pdcp = nullptr;
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srslte::timer_handler* timers = nullptr;
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uint32_t lcid = 0;
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rlc_config_t cfg = {};
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std::string rb_name;
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static const int poll_periodicity = 8; // After how many data PDUs a status PDU shall be requested
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// Rx and Tx objects
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rlc_am_lte_tx tx;
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rlc_am_lte_rx rx;
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rlc_bearer_metrics_t metrics = {};
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};
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/****************************************************************************
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* Header pack/unpack helper functions
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* Ref: 3GPP TS 36.322 v10.0.0 Section 6.2.1
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***************************************************************************/
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void rlc_am_read_data_pdu_header(byte_buffer_t* pdu, rlc_amd_pdu_header_t* header);
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void rlc_am_read_data_pdu_header(uint8_t** payload, uint32_t* nof_bytes, rlc_amd_pdu_header_t* header);
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void rlc_am_write_data_pdu_header(rlc_amd_pdu_header_t* header, byte_buffer_t* pdu);
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void rlc_am_write_data_pdu_header(rlc_amd_pdu_header_t* header, uint8_t** payload);
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void rlc_am_read_status_pdu(byte_buffer_t* pdu, rlc_status_pdu_t* status);
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void rlc_am_read_status_pdu(uint8_t* payload, uint32_t nof_bytes, rlc_status_pdu_t* status);
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void rlc_am_write_status_pdu(rlc_status_pdu_t* status, byte_buffer_t* pdu);
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int rlc_am_write_status_pdu(rlc_status_pdu_t* status, uint8_t* payload);
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uint32_t rlc_am_packed_length(rlc_amd_pdu_header_t* header);
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uint32_t rlc_am_packed_length(rlc_status_pdu_t* status);
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uint32_t rlc_am_packed_length(rlc_amd_retx_t retx);
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bool rlc_am_is_valid_status_pdu(const rlc_status_pdu_t& status);
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bool rlc_am_is_pdu_segment(uint8_t* payload);
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std::string rlc_am_undelivered_sdu_info_to_string(const std::map<uint32_t, pdcp_sdu_info_t>& info_queue);
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void log_rlc_amd_pdu_header_to_string(srslog::log_channel& log_ch, const rlc_amd_pdu_header_t& header);
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bool rlc_am_start_aligned(const uint8_t fi);
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bool rlc_am_end_aligned(const uint8_t fi);
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bool rlc_am_is_unaligned(const uint8_t fi);
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bool rlc_am_not_start_aligned(const uint8_t fi);
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} // namespace srslte
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#endif // SRSLTE_RLC_AM_LTE_H
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