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/* RLC Window (DL 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 "bts.h"
#include "rlc_window_dl.h"
extern "C" {
#include <osmocom/core/utils.h>
#include <osmocom/core/bitvec.h>
#include <osmocom/core/logging.h>
}
static uint16_t bitnum_to_bsn(int bitnum, uint16_t ssn)
{
return (ssn - 1 - bitnum);
}
void gprs_rlc_v_b::reset()
{
for (size_t i = 0; i < ARRAY_SIZE(m_v_b); ++i)
mark_invalid(i);
}
void gprs_rlc_dl_window::reset()
{
m_v_s = 0;
m_v_a = 0;
m_v_b.reset();
}
int gprs_rlc_dl_window::resend_needed() const
{
for (uint16_t bsn = v_a(); bsn != v_s(); bsn = mod_sns(bsn + 1)) {
if (m_v_b.is_nacked(bsn) || m_v_b.is_resend(bsn))
return bsn;
}
return -1;
}
int gprs_rlc_dl_window::mark_for_resend()
{
int resend = 0;
for (uint16_t bsn = v_a(); bsn != v_s(); bsn = mod_sns(bsn + 1)) {
if (m_v_b.is_unacked(bsn)) {
/* mark to be re-send */
m_v_b.mark_resend(bsn);
resend += 1;
}
}
return resend;
}
int gprs_rlc_dl_window::count_unacked()
{
uint16_t unacked = 0;
uint16_t bsn;
for (bsn = v_a(); bsn != v_s(); bsn = mod_sns(bsn + 1)) {
if (!m_v_b.is_acked(bsn))
unacked += 1;
}
return unacked;
}
void gprs_rlc_dl_window::update(struct gprs_rlcmac_bts *bts, const struct bitvec *rbb,
uint16_t first_bsn, uint16_t *lost,
uint16_t *received)
{
unsigned dist = distance();
unsigned num_blocks = rbb->cur_bit > dist
? dist : rbb->cur_bit;
unsigned bsn;
/* first_bsn is in range V(A)..V(S) */
for (unsigned int bitpos = 0; bitpos < num_blocks; bitpos++) {
bool is_ack;
bsn = mod_sns(first_bsn + bitpos);
if (bsn == mod_sns(v_a() - 1))
break;
is_ack = bitvec_get_bit_pos(rbb, bitpos) == 1;
if (is_ack) {
LOGP(DRLCMACDL, LOGL_DEBUG, "- got ack for BSN=%d\n", bsn);
if (!m_v_b.is_acked(bsn))
*received += 1;
m_v_b.mark_acked(bsn);
} else {
LOGP(DRLCMACDL, LOGL_DEBUG, "- got NACK for BSN=%d\n", bsn);
m_v_b.mark_nacked(bsn);
bts_do_rate_ctr_inc(bts, CTR_RLC_NACKED);
*lost += 1;
}
}
}
void gprs_rlc_dl_window::update(struct gprs_rlcmac_bts *bts, char *show_rbb, uint16_t ssn,
uint16_t *lost, uint16_t *received)
{
/* SSN - 1 is in range V(A)..V(S)-1 */
for (int bitpos = 0; bitpos < ws(); bitpos++) {
uint16_t bsn = mod_sns(bitnum_to_bsn(bitpos, ssn));
if (bsn == mod_sns(v_a() - 1))
break;
if (show_rbb[ws() - 1 - bitpos] == 'R') {
LOGP(DRLCMACDL, LOGL_DEBUG, "- got ack for BSN=%d\n", bsn);
if (!m_v_b.is_acked(bsn))
*received += 1;
m_v_b.mark_acked(bsn);
} else {
LOGP(DRLCMACDL, LOGL_DEBUG, "- got NACK for BSN=%d\n", bsn);
m_v_b.mark_nacked(bsn);
bts_do_rate_ctr_inc(bts, CTR_RLC_NACKED);
*lost += 1;
}
}
}
int gprs_rlc_dl_window::move_window()
{
int i;
uint16_t bsn;
int moved = 0;
for (i = 0, bsn = v_a(); bsn != v_s(); i++, bsn = mod_sns(bsn + 1)) {
if (m_v_b.is_acked(bsn)) {
m_v_b.mark_invalid(bsn);
moved += 1;
} else
break;
}
return moved;
}
void gprs_rlc_dl_window::show_state(char *show_v_b)
{
int i;
uint16_t bsn;
for (i = 0, bsn = v_a(); bsn != v_s(); i++, bsn = mod_sns(bsn + 1)) {
uint16_t index = bsn & mod_sns_half();
switch(m_v_b.get_state(index)) {
case GPRS_RLC_DL_BSN_INVALID:
show_v_b[i] = 'I';
break;
case GPRS_RLC_DL_BSN_ACKED:
show_v_b[i] = 'A';
break;
case GPRS_RLC_DL_BSN_RESEND:
show_v_b[i] = 'X';
break;
case GPRS_RLC_DL_BSN_NACKED:
show_v_b[i] = 'N';
break;
default:
show_v_b[i] = '?';
}
}
show_v_b[i] = '\0';
}
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