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/* RLC Window (UL TBF), 3GPP TS 44.060
*
* Copyright (C) 2013 by Holger Hans Peter Freyther
* Copyright (C) 2023 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
*
* 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.
*/
#include "gprs_debug.h"
#include "rlc_window_ul.h"
extern "C" {
#include <osmocom/core/utils.h>
#include <osmocom/core/bitvec.h>
#include <osmocom/core/logging.h>
}
void gprs_rlc_v_n::reset()
{
for (size_t i = 0; i < ARRAY_SIZE(m_v_n); ++i)
m_v_n[i] = GPRS_RLC_UL_BSN_INVALID;
}
/* Raise V(R) to highest received sequence number not received. */
void gprs_rlc_ul_window::raise_v_r(const uint16_t bsn)
{
uint16_t offset_v_r;
offset_v_r = mod_sns(bsn + 1 - v_r());
/* Positive offset, so raise. */
if (offset_v_r < (sns() >> 1)) {
while (offset_v_r--) {
const uint16_t _v_r = v_r();
const uint16_t bsn_no_longer_in_ws = mod_sns(_v_r - ws());
LOGP(DRLCMACUL, LOGL_DEBUG, "- Mark BSN %u as INVALID\n", bsn_no_longer_in_ws);
m_v_n.mark_invalid(bsn_no_longer_in_ws);
if (offset_v_r) {/* all except the received block */
LOGP(DRLCMACUL, LOGL_DEBUG, "- Mark BSN %u as MISSING\n", _v_r);
m_v_n.mark_missing(_v_r);
}
raise_v_r_to(1);
}
LOGP(DRLCMACUL, LOGL_DEBUG, "- Raising V(R) to %d\n", v_r());
}
}
/*
* Raise V(Q) if possible. This is looped until there is a gap
* (non received block) or the window is empty.
*/
uint16_t gprs_rlc_ul_window::raise_v_q()
{
uint16_t count = 0;
while (v_q() != v_r()) {
if (!m_v_n.is_received(v_q()))
break;
LOGP(DRLCMACUL, LOGL_DEBUG, "- Taking block %d out, raising "
"V(Q) to %d\n", v_q(), mod_sns(v_q() + 1));
raise_v_q(1);
count += 1;
}
return count;
}
void gprs_rlc_ul_window::receive_bsn(const uint16_t bsn)
{
m_v_n.mark_received(bsn);
raise_v_r(bsn);
}
bool gprs_rlc_ul_window::invalidate_bsn(const uint16_t bsn)
{
bool was_valid = m_v_n.is_received(bsn);
m_v_n.mark_missing(bsn);
return was_valid;
}
/* Update the receive block bitmap */
uint16_t gprs_rlc_ul_window::update_egprs_rbb(uint8_t *rbb)
{
uint16_t i;
uint16_t bsn;
uint16_t bitmask = 0x80;
int8_t pos = 0;
int8_t bit_pos = 0;
for (i = 0, bsn = (v_q()+1); ((bsn < (v_r())) && (i < ws())); i++,
bsn = this->mod_sns(bsn + 1)) {
if (m_v_n.is_received(bsn)) {
rbb[pos] = rbb[pos] | bitmask;
} else {
rbb[pos] = rbb[pos] & (~bitmask);
}
bitmask = bitmask >> 1;
bit_pos++;
bit_pos = bit_pos % 8;
if (bit_pos == 0) {
pos++;
bitmask = 0x80;
}
}
return i;
}
/* Update the receive block bitmap */
void gprs_rlc_ul_window::update_rbb(char *rbb)
{
int i;
for (i=0; i < ws(); i++) {
if (m_v_n.is_received((ssn()-1-i) & mod_sns()))
rbb[ws()-1-i] = 'R';
else
rbb[ws()-1-i] = 'I';
}
}
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