| /*! \file gsm0502.c |
| * Paging helper code */ |
| /* |
| * (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org> |
| * (C) 2010 by Sylvain Munaut <tnt@246tNt.com> |
| * |
| * 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; |
| } |
| |
| /* Magic numbers (RNTABLE) for pseudo-random hopping sequence generation. */ |
| static const uint8_t rn_table[114] = { |
| 48, 98, 63, 1, 36, 95, 78, 102, 94, 73, |
| 0, 64, 25, 81, 76, 59, 124, 23, 104, 100, |
| 101, 47, 118, 85, 18, 56, 96, 86, 54, 2, |
| 80, 34, 127, 13, 6, 89, 57, 103, 12, 74, |
| 55, 111, 75, 38, 109, 71, 112, 29, 11, 88, |
| 87, 19, 3, 68, 110, 26, 33, 31, 8, 45, |
| 82, 58, 40, 107, 32, 5, 106, 92, 62, 67, |
| 77, 108, 122, 37, 60, 66, 121, 42, 51, 126, |
| 117, 114, 4, 90, 43, 52, 53, 113, 120, 72, |
| 16, 49, 7, 79, 119, 61, 22, 84, 9, 97, |
| 91, 15, 21, 24, 46, 39, 93, 105, 65, 70, |
| 125, 99, 17, 123, |
| }; |
| |
| /*! Hopping sequence generation as per 3GPP TS 45.002, section 6.2.3. |
| * \param[in] t GSM time (TDMA frame number, T1/T2/T3). |
| * \param[in] hsn Hopping Sequence Number. |
| * \param[in] maio Mobile Allocation Index Offset. |
| * \param[in] n number of entries in mobile allocation (arfcn table). |
| * \param[in] ma array of ARFCNs (sorted in ascending order) |
| * representing the Mobile Allocation. |
| * \returns ARFCN to use for given input parameters at time 't' |
| * or Mobile Allocation Index if ma == NULL. |
| */ |
| uint16_t gsm0502_hop_seq_gen(const struct gsm_time *t, |
| uint8_t hsn, uint8_t maio, |
| size_t n, const uint16_t *ma) |
| { |
| unsigned int mai; |
| |
| if (hsn == 0) { |
| /* cyclic hopping */ |
| mai = (t->fn + maio) % n; |
| } else { |
| /* pseudo random hopping */ |
| int m, mp, tp, s, pnm; |
| |
| pnm = (n >> 0) | (n >> 1) |
| | (n >> 2) | (n >> 3) |
| | (n >> 4) | (n >> 5) |
| | (n >> 6); |
| |
| m = t->t2 + rn_table[(hsn ^ (t->t1 & 63)) + t->t3]; |
| mp = m & pnm; |
| |
| if (mp < n) |
| s = mp; |
| else { |
| tp = t->t3 & pnm; |
| s = (mp + tp) % n; |
| } |
| |
| mai = (s + maio) % n; |
| } |
| |
| return ma ? ma[mai] : mai; |
| } |