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