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Diffstat (limited to 'src/coding/gsm0503_amr_dtx.c')
| -rw-r--r-- | src/coding/gsm0503_amr_dtx.c | 314 |
1 files changed, 314 insertions, 0 deletions
diff --git a/src/coding/gsm0503_amr_dtx.c b/src/coding/gsm0503_amr_dtx.c new file mode 100644 index 00000000..724cf091 --- /dev/null +++ b/src/coding/gsm0503_amr_dtx.c @@ -0,0 +1,314 @@ +/* + * (C) 2020 by sysmocom - s.f.m.c. GmbH, Author: Philipp Maier + * 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 <stdio.h> +#include <stdint.h> +#include <string.h> +#include <stdlib.h> +#include <errno.h> + +#include <osmocom/core/bits.h> +#include <osmocom/core/conv.h> +#include <osmocom/core/utils.h> +#include <osmocom/coding/gsm0503_amr_dtx.h> +#include <osmocom/coding/gsm0503_parity.h> +#include <osmocom/gsm/gsm0503.h> + +/* See also: 3GPP TS 05.03, chapter 3.10.1.3, 3.10.5.2 Identification marker */ +static const ubit_t id_marker_1[] = { 1, 0, 1, 1, 0, 0, 0, 0, 1 }; + +/* See also: 3GPP TS 05.03, chapter 3.9.1.3, 3.10.2.2, 3.10.2.2 Identification marker */ +static const ubit_t id_marker_0[] = { 0, 1, 0, 0, 1, 1, 1, 1, 0 }; + +/* See also: 3GPP TS 05.03, chapter 3.9 Adaptive multi rate speech channel at full rate (TCH/AFS) */ +static const ubit_t codec_mode_1_sid[] = { 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0 }; +static const ubit_t codec_mode_2_sid[] = { 0, 0, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0 }; +static const ubit_t codec_mode_3_sid[] = { 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1 }; +static const ubit_t codec_mode_4_sid[] = { 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1 }; + +const struct value_string gsm0503_amr_dtx_frame_names[] = { + { AFS_SID_FIRST, "AFS_SID_FIRST" }, + { AFS_SID_UPDATE, "AFS_SID_UPDATE" }, + { AFS_ONSET, "AFS_ONSET" }, + { AHS_SID_UPDATE, "AHS_SID_UPDATE" }, + { AHS_SID_FIRST_P1, "AHS_SID_FIRST_P1" }, + { AHS_SID_FIRST_P2, "AHS_SID_FIRST_P2" }, + { AHS_ONSET, "AHS_ONSET" }, + { AHS_SID_FIRST_INH, "AHS_SID_FIRST_INH" }, + { AHS_SID_UPDATE_INH, "AHS_SID_UPDATE_INH" }, + { AMR_OTHER, "NON DTX FRAME (OTHER)" }, + { 0, NULL } +}; + +static bool detect_afs_id_marker(int *n_errors, int *n_bits_total, const ubit_t * ubits, uint8_t offset, uint8_t count, + const ubit_t * id_marker, uint8_t id_marker_len) +{ + unsigned int i, k; + unsigned int id_bit_nr = 0; + int errors = 0; + int bits = 0; + + /* Override coded in-band data */ + ubits += offset; + + /* Check for identification marker bits */ + for (i = 0; i < count; i++) { + for (k = 0; k < 4; k++) { + if (id_marker[id_bit_nr % id_marker_len] != *ubits) + errors++; + id_bit_nr++; + ubits++; + bits++; + } + + /* Jump to the next block of 4 bits */ + ubits += 4; + } + + *n_errors = errors; + *n_bits_total = bits; + + /* Tolerate up to 1/8 errornous bits */ + return *n_errors < *n_bits_total / 8; +} + +static bool detect_ahs_id_marker(int *n_errors, int *n_bits_total, const ubit_t * ubits, const ubit_t * id_marker) +{ + unsigned int i, k; + int errors = 0; + int bits = 0; + + /* Override coded in-band data */ + ubits += 16; + + /* Check first identification marker bits (23*9 bits) */ + for (i = 0; i < 23; i++) { + for (k = 0; k < 9; k++) { + if (id_marker[k] != *ubits) + errors++; + ubits++; + bits++; + } + } + + /* Check remaining identification marker bits (5 bits) */ + for (k = 0; k < 5; k++) { + if (id_marker[k] != *ubits) + errors++; + ubits++; + bits++; + } + + *n_errors = errors; + *n_bits_total = bits; + + /* Tolerate up to 1/8 errornous bits */ + return *n_errors < *n_bits_total / 8; +} + +static bool detect_interleaved_ahs_id_marker(int *n_errors, int *n_bits_total, const ubit_t * ubits, uint8_t offset, + uint8_t n_bits, const ubit_t * id_marker, uint8_t id_marker_len) +{ + unsigned int i, k; + int errors = 0; + int bits = 0; + uint8_t full_rounds = n_bits / id_marker_len; + uint8_t remainder = n_bits % id_marker_len; + + /* Override coded in-band data */ + ubits += offset; + + /* Check first identification marker bits (23*9 bits) */ + for (i = 0; i < full_rounds; i++) { + for (k = 0; k < id_marker_len; k++) { + if (id_marker[k] != *ubits) + errors++; + ubits += 2; + bits++; + } + } + + /* Check remaining identification marker bits (5 bits) */ + for (k = 0; k < remainder; k++) { + if (id_marker[k] != *ubits) + errors++; + ubits += 2; + bits++; + } + + *n_errors = errors; + *n_bits_total = bits; + + /* Tolerate up to 1/8 errornous bits */ + return *n_errors < *n_bits_total / 8; +} + +/* Detect a an FR AMR SID_FIRST frame by its identifcation marker */ +static bool detect_afs_sid_first(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + return detect_afs_id_marker(n_errors, n_bits_total, ubits, 32, 53, id_marker_0, 9); +} + +/* Detect an FR AMR SID_FIRST frame by its identification marker */ +static bool detect_afs_sid_update(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + return detect_afs_id_marker(n_errors, n_bits_total, ubits, 36, 53, id_marker_0, 9); +} + +/* Detect an FR AMR SID_FIRST frame by its repeating coded inband data */ +static bool detect_afs_onset(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + bool rc; + + rc = detect_afs_id_marker(n_errors, n_bits_total, ubits, 4, 57, codec_mode_1_sid, 16); + if (rc) + return true; + + rc = detect_afs_id_marker(n_errors, n_bits_total, ubits, 4, 57, codec_mode_2_sid, 16); + if (rc) + return true; + + rc = detect_afs_id_marker(n_errors, n_bits_total, ubits, 4, 57, codec_mode_3_sid, 16); + if (rc) + return true; + + rc = detect_afs_id_marker(n_errors, n_bits_total, ubits, 4, 57, codec_mode_4_sid, 16); + if (rc) + return true; + + return false; +} + +/* Detect an HR AMR SID UPDATE frame by its identification marker */ +static bool detect_ahs_sid_update(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + return detect_ahs_id_marker(n_errors, n_bits_total, ubits, id_marker_1); +} + +/* Detect an HR AMR SID FIRST (part 1) frame by its identification marker */ +static bool detect_ahs_sid_first_p1(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + return detect_ahs_id_marker(n_errors, n_bits_total, ubits, id_marker_0); +} + +/* Detect an HR AMR SID FIRST (part 2) frame by its repeating coded inband data */ +static bool detect_ahs_sid_first_p2(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + bool rc; + + rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 0, 114, codec_mode_1_sid, 16); + if (rc) + return true; + + rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 0, 114, codec_mode_2_sid, 16); + if (rc) + return true; + + rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 0, 114, codec_mode_3_sid, 16); + if (rc) + return true; + + rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 0, 114, codec_mode_4_sid, 16); + if (rc) + return true; + + return false; +} + +/* Detect an HR AMR ONSET frame by its repeating coded inband data */ +static bool detect_ahs_onset(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + bool rc; + + rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 1, 114, codec_mode_1_sid, 16); + if (rc) + return true; + + rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 1, 114, codec_mode_2_sid, 16); + if (rc) + return true; + + rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 1, 114, codec_mode_3_sid, 16); + if (rc) + return true; + + rc = detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 1, 114, codec_mode_4_sid, 16); + if (rc) + return true; + + return false; +} + +/* Detect an HR AMR SID FIRST INHIBIT frame by its identification marker */ +static bool detect_ahs_sid_first_inh(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + return detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 33, 212, id_marker_1, 9); +} + +/* Detect an HR AMR SID UPDATE INHIBIT frame by its identification marker */ +static bool detect_ahs_sid_update_inh(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + return detect_interleaved_ahs_id_marker(n_errors, n_bits_total, ubits, 33, 212, id_marker_0, 9); +} + +/*! Detect FR AMR DTX frame in unmapped, deinterleaved frame bits. + * \param[in] ubits input bits (456 bit). + * \param[out] n_errors number of errornous bits. + * \param[out] n_bits_total number of checked bits. + * \returns dtx frame type. */ +enum gsm0503_amr_dtx_frames gsm0503_detect_afs_dtx_frame(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + if (detect_afs_sid_first(n_errors, n_bits_total, ubits)) + return AFS_SID_FIRST; + if (detect_afs_sid_update(n_errors, n_bits_total, ubits)) + return AFS_SID_UPDATE; + if (detect_afs_onset(n_errors, n_bits_total, ubits)) + return AFS_ONSET; + + *n_errors = 0; + *n_bits_total = 0; + return AMR_OTHER; +} + +/*! Detect HR AMR DTX frame in unmapped, deinterleaved frame bits. + * \param[in] ubits input bits (456 bit). + * \param[out] n_errors number of errornous bits. + * \param[out] n_bits_total number of checked bits. + * \returns dtx frame type, */ +enum gsm0503_amr_dtx_frames gsm0503_detect_ahs_dtx_frame(int *n_errors, int *n_bits_total, const ubit_t * ubits) +{ + if (detect_ahs_sid_update(n_errors, n_bits_total, ubits)) + return AHS_SID_UPDATE; + if (detect_ahs_sid_first_inh(n_errors, n_bits_total, ubits)) + return AHS_SID_FIRST_INH; + if (detect_ahs_sid_update_inh(n_errors, n_bits_total, ubits)) + return AHS_SID_UPDATE_INH; + if (detect_ahs_sid_first_p1(n_errors, n_bits_total, ubits)) + return AHS_SID_FIRST_P1; + if (detect_ahs_sid_first_p2(n_errors, n_bits_total, ubits)) + return AHS_SID_FIRST_P2; + if (detect_ahs_onset(n_errors, n_bits_total, ubits)) + return AHS_ONSET; + + *n_errors = 0; + *n_bits_total = 0; + return AMR_OTHER; +} |