mirror of https://gerrit.osmocom.org/osmo-tetra
72 lines
1.9 KiB
C
72 lines
1.9 KiB
C
/* (C) 2011 by Sylvain Munaut <tnt@246tNt.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 Affero General Public License as published by
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* the Free Software Foundation; either version 3 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 Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero 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 <string.h>
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#include <osmocom/core/conv.h>
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#include <lower_mac/viterbi_tch.h>
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/*
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* G1 = 1 + D + D2 + D3 + D4
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* G2 = 1 + D + D3 + D4
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* G3 = 1 + D2 + D4
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*/
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static const uint8_t conv_tch_next_output[][2] = {
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{ 0, 7 }, { 6, 1 }, { 5, 2 }, { 3, 4 },
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{ 6, 1 }, { 0, 7 }, { 3, 4 }, { 5, 2 },
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{ 7, 0 }, { 1, 6 }, { 2, 5 }, { 4, 3 },
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{ 1, 6 }, { 7, 0 }, { 4, 3 }, { 2, 5 },
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};
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static const uint8_t conv_tch_next_state[][2] = {
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{ 0, 1 }, { 2, 3 }, { 4, 5 }, { 6, 7 },
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{ 8, 9 }, { 10, 11 }, { 12, 13 }, { 14, 15 },
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{ 0, 1 }, { 2, 3 }, { 4, 5 }, { 6, 7 },
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{ 8, 9 }, { 10, 11 }, { 12, 13 }, { 14, 15 },
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};
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static const struct osmo_conv_code conv_tch = {
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.N = 4,
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.K = 5,
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.next_output = conv_tch_next_output,
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.next_state = conv_tch_next_state,
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};
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int conv_tch_decode(int8_t *input, uint8_t *output, int n)
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{
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struct osmo_conv_decoder decoder;
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int rv, l;
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osmo_conv_decode_init(&decoder, &conv_tch, n);
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l = osmo_conv_decode_scan(&decoder, input, n);
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l = osmo_conv_decode_finish(&decoder, &input[l]);
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rv = osmo_conv_decode_get_output(&decoder, output, 1);
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osmo_conv_decode_deinit(&decoder);
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return rv;
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}
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