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/*! \file gsm0502.c
* Paging helper code */
/*
* (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
* All Rights Reserved
*
* SPDX-License-Identifier: GPL-2.0+
*
* 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, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdint.h>
#include <osmocom/gsm/protocol/gsm_04_08.h>
#include <osmocom/gsm/gsm0502.h>
#include <osmocom/gsm/gsm48.h>
#include <osmocom/gsm/rsl.h>
#include <osmocom/gsm/gsm_utils.h>
#include <osmocom/core/logging.h>
#include <inttypes.h>
unsigned int
gsm0502_calc_paging_group(struct gsm48_control_channel_descr *chan_desc, uint64_t imsi)
{
int ccch_conf;
int bs_cc_chans;
int blocks;
unsigned int group;
ccch_conf = chan_desc->ccch_conf;
bs_cc_chans = rsl_ccch_conf_to_bs_cc_chans(ccch_conf);
/* code word + 2, as 2 channels equals 0x0 */
blocks = gsm48_number_of_paging_subchannels(chan_desc);
group = gsm0502_get_paging_group(imsi, bs_cc_chans, blocks);
return group;
}
/* Clause 7 Table 1 of 5 Mapping of logical channels onto physical channels */
#define TCH_REPEAT_LENGTH 13
#define FACCH_F_REPEAT_LENGTH 13
#define FACCH_H_REPEAT_LENGTH 26
static const uint8_t gsm0502_tch_f_traffic_block_map[3][8] = {
{0, 1, 2, 3, 4, 5, 6, 7},
{4, 5, 6, 7, 8, 9, 10, 11},
{8, 9, 10, 11, 0, 1, 2, 3}
};
static const uint8_t gsm0502_tch_h0_traffic_block_map[3][4] = {
{0, 2, 4, 6},
{4, 6, 8, 10},
{8, 10, 0, 2}
};
static const uint8_t gsm0502_tch_h1_traffic_block_map[3][4] = {
{1, 3, 5, 7},
{5, 7, 9, 11},
{9, 11, 1, 3}
};
static const uint8_t gsm0502_tch_f_facch_block_map[3][8] = {
{0, 1, 2, 3, 4, 5, 6, 7},
{4, 5, 6, 7, 8, 9, 10, 11},
{8, 9, 10, 11, 0, 1, 2, 3}
};
static const uint8_t gsm0502_tch_h0_facch_block_map[3][6] = {
{0, 2, 4, 6, 8, 10},
{8, 10, 13, 15, 17, 19},
{17, 19, 21, 23, 0, 2}
};
static const uint8_t gsm0502_tch_h1_facch_block_map[3][6] = {
{1, 3, 5, 7, 9, 11},
{9, 11, 14, 16, 18, 20},
{18, 20, 22, 24, 1, 3}
};
/* Struct to describe a remapping function for block frame nbumbers. The member
* blockend describes the ending of a block for which we want to determine the
* beginning frame number. The member distance describes the value we need to
* subtract from the blockend frame number in order to get the beginning of the
* the block. The member cycle describes the Repeat length in TDMA frames we
* are dealing with. For traffic channels this is always 13, for control
* channels it is different. The member len simply defines amount of
* blockendings and distances we store in the remap table */
struct fn_remap_table {
unsigned int cycle;
unsigned int len;
uint8_t blockend[8];
uint8_t distance[8];
};
/* Memory to hold the remap tables we will automatically generate on startup */
static struct fn_remap_table tch_f_remap_table;
static struct fn_remap_table tch_h0_remap_table;
static struct fn_remap_table tch_h1_remap_table;
static struct fn_remap_table facch_f_remap_table;
static struct fn_remap_table facch_h0_remap_table;
static struct fn_remap_table facch_h1_remap_table;
static struct fn_remap_table *fn_remap_table_ptr[FN_REMAP_MAX];
/* Generate a remap table from a given block map. A block map lists the block
* layout as defined in GSM 05.02, Clause 7 Table 1 of 5, one block per row.
* Parameters:
* table: name of the remap table to output
* map: traffic block map input
* rows: length of the traffic block map
* cols: witdh of the traffic block map
* repeat: repeat length in TDMA frames (cycle) */
#define fn_remap_table_from_traffic_block_map(table, map, rows, cols, repeat) \
for(i=0;i<rows;i++) { \
table.blockend[i] = map[i][cols-1]; \
if(map[i][0] <= map[i][cols-1]) \
table.distance[i] = map[i][cols-1] - map[i][0]; \
else \
table.distance[i] = repeat - map[i][0] + map[i][cols-1]; \
} \
table.cycle = repeat; \
table.len = rows;
/* Automatically generate fn remap tables on startupmake */
static __attribute__ ((constructor))
void fn_remap_tables_build(void)
{
/* Required by macro */
unsigned int i;
/* Generate tables */
fn_remap_table_from_traffic_block_map(tch_f_remap_table,
gsm0502_tch_f_traffic_block_map, 3, 8,
TCH_REPEAT_LENGTH);
fn_remap_table_from_traffic_block_map(tch_h0_remap_table,
gsm0502_tch_h0_traffic_block_map, 3, 4,
TCH_REPEAT_LENGTH);
fn_remap_table_from_traffic_block_map(tch_h1_remap_table,
gsm0502_tch_h1_traffic_block_map, 3, 4,
TCH_REPEAT_LENGTH);
fn_remap_table_from_traffic_block_map(facch_f_remap_table,
gsm0502_tch_f_facch_block_map, 3, 8,
FACCH_F_REPEAT_LENGTH);
fn_remap_table_from_traffic_block_map(facch_h0_remap_table,
gsm0502_tch_h0_facch_block_map, 3, 6,
FACCH_H_REPEAT_LENGTH);
fn_remap_table_from_traffic_block_map(facch_h1_remap_table,
gsm0502_tch_h1_facch_block_map, 3, 6,
FACCH_H_REPEAT_LENGTH);
fn_remap_table_ptr[FN_REMAP_TCH_F] = &tch_f_remap_table;
fn_remap_table_ptr[FN_REMAP_TCH_H0] = &tch_h0_remap_table;
fn_remap_table_ptr[FN_REMAP_TCH_H1] = &tch_h1_remap_table;
fn_remap_table_ptr[FN_REMAP_FACCH_F] = &facch_f_remap_table;
fn_remap_table_ptr[FN_REMAP_FACCH_H0] = &facch_h0_remap_table;
fn_remap_table_ptr[FN_REMAP_FACCH_H1] = &facch_h1_remap_table;
}
/*! Calculate the frame number of the beginning of a block.
* \param[in] fn frame number of the block ending.
* \param[in] channel channel type (see also enum fn_remap_channel).
* \returns frame number of the beginning of the block or input frame number if
* remapping was not possible. */
uint32_t gsm0502_fn_remap(uint32_t fn, enum gsm0502_fn_remap_channel channel)
{
uint8_t fn_cycle;
uint8_t i;
int sub = -1;
uint32_t fn_map;
struct fn_remap_table *table;
OSMO_ASSERT(channel < ARRAY_SIZE(fn_remap_table_ptr));
table = fn_remap_table_ptr[(uint8_t)channel];
fn_cycle = fn % table->cycle;
for (i = 0; i < table->len; i++) {
if (table->blockend[i] == fn_cycle) {
sub = table->distance[i];
break;
}
}
if (sub == -1) {
LOGP(DLGLOBAL, LOGL_ERROR, "could not remap frame number!, fn=%"PRIu32"\n", fn);
return fn;
}
fn_map = (fn + GSM_MAX_FN - sub) % GSM_MAX_FN;
return fn_map;
}
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