184 lines
4.9 KiB
C
184 lines
4.9 KiB
C
/*
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* OsmocomBB <-> SDR connection bridge
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* TDMA scheduler: handlers for DL / UL bursts on logical channels
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*
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* (C) 2018 by Vadim Yanitskiy <axilirator@gmail.com>
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*
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* All Rights Reserved
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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 along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <errno.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include "scheduler.h"
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#include "sched_trx.h"
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static const uint8_t tch_h0_traffic_block_map[3][4] = {
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/* B0(0,2,4,6), B1(4,6,8,10), B2(8,10,0,2) */
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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 tch_h1_traffic_block_map[3][4] = {
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/* B0(1,3,5,7), B1(5,7,9,11), B2(9,11,1,3) */
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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 tch_h0_dl_facch_block_map[3][6] = {
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/* B0(4,6,8,10,13,15), B1(13,15,17,19,21,23), B2(21,23,0,2,4,6) */
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{ 4, 6, 8, 10, 13, 15 },
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{ 13, 15, 17, 19, 21, 23 },
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{ 21, 23, 0, 2, 4, 6 },
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};
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static const uint8_t tch_h0_ul_facch_block_map[3][6] = {
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/* B0(0,2,4,6,8,10), B1(8,10,13,15,17,19), B2(17,19,21,23,0,2) */
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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 tch_h1_dl_facch_block_map[3][6] = {
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/* B0(5,7,9,11,14,16), B1(14,16,18,20,22,24), B2(22,24,1,3,5,7) */
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{ 5, 7, 9, 11, 14, 16 },
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{ 14, 16, 18, 20, 22, 24 },
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{ 22, 24, 1, 3, 5, 7 },
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};
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const uint8_t tch_h1_ul_facch_block_map[3][6] = {
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/* B0(1,3,5,7,9,11), B1(9,11,14,16,18,20), B2(18,20,22,24,1,3) */
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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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/**
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* Can a TCH/H block transmission be initiated / finished
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* on a given frame number and a given channel type?
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*
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* See GSM 05.02, clause 7, table 1
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*
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* @param chan channel type (TRXC_TCHH_0 or TRXC_TCHH_1)
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* @param fn the current frame number
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* @param ul Uplink or Downlink?
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* @param facch FACCH/H or traffic?
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* @param start init or end of transmission?
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* @return true (yes) or false (no)
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*/
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bool sched_tchh_block_map_fn(enum trx_lchan_type chan,
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uint32_t fn, bool ul, bool facch, bool start)
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{
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uint8_t fn_mf;
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int i = 0;
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/* Just to be sure */
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OSMO_ASSERT(chan == TRXC_TCHH_0 || chan == TRXC_TCHH_1);
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/* Calculate a modulo */
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fn_mf = facch ? (fn % 26) : (fn % 13);
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#define MAP_GET_POS(map) \
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(start ? 0 : ARRAY_SIZE(map[i]) - 1)
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#define BLOCK_MAP_FN(map) \
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do { \
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if (map[i][MAP_GET_POS(map)] == fn_mf) \
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return true; \
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} while (++i < ARRAY_SIZE(map))
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/* Choose a proper block map */
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if (facch) {
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if (ul) {
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if (chan == TRXC_TCHH_0)
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BLOCK_MAP_FN(tch_h0_ul_facch_block_map);
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else
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BLOCK_MAP_FN(tch_h1_ul_facch_block_map);
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} else {
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if (chan == TRXC_TCHH_0)
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BLOCK_MAP_FN(tch_h0_dl_facch_block_map);
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else
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BLOCK_MAP_FN(tch_h1_dl_facch_block_map);
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}
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} else {
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if (chan == TRXC_TCHH_0)
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BLOCK_MAP_FN(tch_h0_traffic_block_map);
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else
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BLOCK_MAP_FN(tch_h1_traffic_block_map);
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}
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return false;
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}
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/**
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* Calculates a frame number of the first burst
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* using given frame number of the last burst.
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*
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* See GSM 05.02, clause 7, table 1
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*
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* @param chan channel type (TRXC_TCHH_0 or TRXC_TCHH_1)
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* @param last_fn frame number of the last burst
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* @param facch FACCH/H or traffic?
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* @return either frame number of the first burst,
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* or fn=last_fn if calculation failed
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*/
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uint32_t sched_tchh_block_dl_first_fn(enum trx_lchan_type chan,
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uint32_t last_fn, bool facch)
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{
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uint8_t fn_mf, fn_diff;
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int i = 0;
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/* Just to be sure */
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OSMO_ASSERT(chan == TRXC_TCHH_0 || chan == TRXC_TCHH_1);
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/* Calculate a modulo */
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fn_mf = facch ? (last_fn % 26) : (last_fn % 13);
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#define BLOCK_FIRST_FN(map) \
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do { \
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if (map[i][ARRAY_SIZE(map[i]) - 1] == fn_mf) { \
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fn_diff = TDMA_FN_DIFF(fn_mf, map[i][0]); \
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return TDMA_FN_SUB(last_fn, fn_diff); \
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} \
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} while (++i < ARRAY_SIZE(map))
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/* Choose a proper block map */
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if (facch) {
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if (chan == TRXC_TCHH_0)
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BLOCK_FIRST_FN(tch_h0_dl_facch_block_map);
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else
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BLOCK_FIRST_FN(tch_h1_dl_facch_block_map);
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} else {
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if (chan == TRXC_TCHH_0)
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BLOCK_FIRST_FN(tch_h0_traffic_block_map);
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else
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BLOCK_FIRST_FN(tch_h1_traffic_block_map);
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}
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LOGP(DSCHD, LOGL_ERROR, "Failed to calculate TDMA "
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"frame number of the first burst of %s block, "
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"using the current fn=%u\n", facch ?
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"FACCH/H" : "TCH/H", last_fn);
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/* Couldn't calculate the first fn, return the last */
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return last_fn;
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}
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