mirror of https://gerrit.osmocom.org/libosmocore
304 lines
11 KiB
C
304 lines
11 KiB
C
/*************************************************************************
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* GSM CSD modified V.110 frame decoding/encoding (ubits <-> struct with D/S/X/E bits)
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*************************************************************************/
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/* (C) 2022 by Harald Welte <laforge@osmocom.org>
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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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#include <errno.h>
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#include <osmocom/core/bits.h>
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#include <osmocom/isdn/v110.h>
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/*! Decode a 60-bit GSM 12kbit/s CSD frame present as 60 ubits into a struct osmo_v110_decoded_frame.
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* \param[out] caller-allocated output data structure, filled by this function
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* \param[in] ra_bits One V.110 frame as 60 unpacked bits. */
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int osmo_csd_12k_6k_decode_frame(struct osmo_v110_decoded_frame *fr, const ubit_t *ra_bits, size_t n_bits)
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{
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/* 3GPP TS 44.021 Section 8.1.2 / 8.1.3
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D1 D2 D3 D4 D5 D6 S1
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D7 D8 D9 D10 D11 D12 X
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D13 D14 D15 D16 D17 D18 S3
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D19 D20 D21 D22 D23 D24 S4
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E4 E5 E6 E7 D25 D26 D27
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D28 D29 D30 S6 D31 D32 D33
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D34 D35 D36 X D37 D38 D39
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D40 D41 D42 S8 D43 D44 D45
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D46 D47 D48 S9 */
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if (n_bits < 60)
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return -EINVAL;
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/* X1 .. X2 */
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fr->x_bits[0] = ra_bits[1 * 7 + 6];
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fr->x_bits[1] = ra_bits[6 * 7 + 3];
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/* S1, S3, S4, S6, S8, S9 */
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fr->s_bits[0] = ra_bits[0 * 7 + 6];
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fr->s_bits[2] = ra_bits[2 * 7 + 6];
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fr->s_bits[3] = ra_bits[3 * 7 + 6];
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fr->s_bits[5] = ra_bits[5 * 7 + 3];
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fr->s_bits[7] = ra_bits[7 * 7 + 3];
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fr->s_bits[8] = ra_bits[8 * 7 + 3];
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/* E1 .. E3 must be set by out-of-band knowledge! */
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/* E4 .. E7 */
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memcpy(fr->e_bits+3, ra_bits + 4 * 7 + 0, 4);
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/* D-bits */
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memcpy(fr->d_bits + 0 * 6 + 0, ra_bits + 0 * 7 + 0, 6);
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memcpy(fr->d_bits + 1 * 6 + 0, ra_bits + 1 * 7 + 0, 6);
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memcpy(fr->d_bits + 2 * 6 + 0, ra_bits + 2 * 7 + 0, 6);
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memcpy(fr->d_bits + 3 * 6 + 0, ra_bits + 3 * 7 + 0, 6);
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memcpy(fr->d_bits + 4 * 6 + 0, ra_bits + 4 * 7 + 4, 3);
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memcpy(fr->d_bits + 4 * 6 + 3, ra_bits + 5 * 7 + 0, 3);
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memcpy(fr->d_bits + 5 * 6 + 0, ra_bits + 5 * 7 + 4, 3);
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memcpy(fr->d_bits + 5 * 6 + 3, ra_bits + 6 * 7 + 0, 3);
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memcpy(fr->d_bits + 6 * 6 + 0, ra_bits + 6 * 7 + 4, 3);
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memcpy(fr->d_bits + 6 * 6 + 3, ra_bits + 7 * 7 + 0, 3);
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memcpy(fr->d_bits + 7 * 6 + 0, ra_bits + 7 * 7 + 4, 3);
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memcpy(fr->d_bits + 7 * 6 + 3, ra_bits + 8 * 7 + 0, 3);
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return 0;
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}
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int osmo_csd_12k_6k_encode_frame(ubit_t *ra_bits, size_t ra_bits_size, const struct osmo_v110_decoded_frame *fr)
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{
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if (ra_bits_size < 60)
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return -EINVAL;
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/* X1 .. X2 */
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ra_bits[1 * 7 + 6] = fr->x_bits[0];
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ra_bits[6 * 7 + 3] = fr->x_bits[1];
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/* S1, S3, S4, S6, S8, S9 */
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ra_bits[0 * 7 + 6] = fr->s_bits[0];
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ra_bits[2 * 7 + 6] = fr->s_bits[2];
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ra_bits[3 * 7 + 6] = fr->s_bits[3];
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ra_bits[5 * 7 + 3] = fr->s_bits[5];
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ra_bits[7 * 7 + 3] = fr->s_bits[7];
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ra_bits[8 * 7 + 3] = fr->s_bits[8];
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/* E1 .. E3 are dropped */
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/* E4 .. E7 */
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memcpy(ra_bits + 4 * 7 + 0, fr->e_bits+3, 4);
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/* D-bits */
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memcpy(ra_bits + 0 * 7 + 0, fr->d_bits + 0 * 6 + 0, 6);
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memcpy(ra_bits + 1 * 7 + 0, fr->d_bits + 1 * 6 + 0, 6);
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memcpy(ra_bits + 2 * 7 + 0, fr->d_bits + 2 * 6 + 0, 6);
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memcpy(ra_bits + 3 * 7 + 0, fr->d_bits + 3 * 6 + 0, 6);
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memcpy(ra_bits + 4 * 7 + 4, fr->d_bits + 4 * 6 + 0, 3);
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memcpy(ra_bits + 5 * 7 + 0, fr->d_bits + 4 * 6 + 3, 3);
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memcpy(ra_bits + 5 * 7 + 4, fr->d_bits + 5 * 6 + 0, 3);
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memcpy(ra_bits + 6 * 7 + 0, fr->d_bits + 5 * 6 + 3, 3);
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memcpy(ra_bits + 6 * 7 + 4, fr->d_bits + 6 * 6 + 0, 3);
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memcpy(ra_bits + 7 * 7 + 0, fr->d_bits + 6 * 6 + 3, 3);
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memcpy(ra_bits + 7 * 7 + 4, fr->d_bits + 7 * 6 + 0, 3);
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memcpy(ra_bits + 8 * 7 + 0, fr->d_bits + 7 * 6 + 3, 3);
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return 60;
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}
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/*! Decode a 36-bit GSM 3k6kbit/s CSD frame present as 36 ubits into a struct osmo_v110_decoded_frame.
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* \param[out] caller-allocated output data structure, filled by this function
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* \param[in] ra_bits One V.110 frame as 36 unpacked bits. */
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int osmo_csd_3k6_decode_frame(struct osmo_v110_decoded_frame *fr, const ubit_t *ra_bits, size_t n_bits)
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{
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/* 3GPP TS 44.021 Section 8.1.4
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D1 D2 D3 S1 D4 D5 D6 X
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D7 D8 D9 S3 D10 D11 D12 S4
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E4 E5 E6 E7 D13 D14 D15 S6
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D16 D17 D18 X D19 D20 D21 S8
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D22 D23 D24 S9
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*/
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if (n_bits < 36)
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return -EINVAL;
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/* X1 .. X2 */
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fr->x_bits[0] = ra_bits[0 * 8 + 7];
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fr->x_bits[1] = ra_bits[3 * 8 + 3];
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/* S1, S3, S4, S6, S8, S9 */
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fr->s_bits[0] = ra_bits[0 * 8 + 3];
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fr->s_bits[2] = ra_bits[1 * 8 + 3];
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fr->s_bits[3] = ra_bits[1 * 8 + 7];
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fr->s_bits[5] = ra_bits[2 * 8 + 7];
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fr->s_bits[7] = ra_bits[3 * 8 + 7];
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fr->s_bits[8] = ra_bits[4 * 8 + 3];
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/* E1 .. E3 must be set by out-of-band knowledge! */
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/* E4 .. E7 */
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memcpy(fr->e_bits+3, ra_bits + 2 * 8 + 0, 4);
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/* D-bits */
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unsigned int d_idx = 0;
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 0]; /* D1 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 0]; /* D1 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 1]; /* D2 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 1]; /* D2 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 2]; /* D3 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 2]; /* D3 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 4]; /* D4 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 4]; /* D4 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 5]; /* D5 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 5]; /* D5 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 6]; /* D6 */
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fr->d_bits[d_idx++] = ra_bits[0 * 8 + 6]; /* D6 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 0]; /* D7 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 0]; /* D7 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 1]; /* D8 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 1]; /* D8 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 2]; /* D9 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 2]; /* D9 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 4]; /* D10 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 4]; /* D10 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 5]; /* D11 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 5]; /* D11 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 6]; /* D12 */
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fr->d_bits[d_idx++] = ra_bits[1 * 8 + 6]; /* D12 */
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fr->d_bits[d_idx++] = ra_bits[2 * 8 + 4]; /* D13 */
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fr->d_bits[d_idx++] = ra_bits[2 * 8 + 4]; /* D13 */
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fr->d_bits[d_idx++] = ra_bits[2 * 8 + 5]; /* D14 */
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fr->d_bits[d_idx++] = ra_bits[2 * 8 + 5]; /* D14 */
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fr->d_bits[d_idx++] = ra_bits[2 * 8 + 6]; /* D15 */
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fr->d_bits[d_idx++] = ra_bits[2 * 8 + 6]; /* D15 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 0]; /* D16 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 0]; /* D16 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 1]; /* D17 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 1]; /* D17 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 2]; /* D18 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 2]; /* D18 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 4]; /* D19 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 4]; /* D19 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 5]; /* D20 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 5]; /* D20 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 6]; /* D21 */
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fr->d_bits[d_idx++] = ra_bits[3 * 8 + 6]; /* D21 */
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fr->d_bits[d_idx++] = ra_bits[4 * 8 + 0]; /* D22 */
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fr->d_bits[d_idx++] = ra_bits[4 * 8 + 0]; /* D22 */
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fr->d_bits[d_idx++] = ra_bits[4 * 8 + 1]; /* D23 */
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fr->d_bits[d_idx++] = ra_bits[4 * 8 + 1]; /* D23 */
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fr->d_bits[d_idx++] = ra_bits[4 * 8 + 2]; /* D24 */
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fr->d_bits[d_idx++] = ra_bits[4 * 8 + 2]; /* D24 */
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OSMO_ASSERT(d_idx == 48);
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return 0;
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}
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int osmo_csd_3k6_encode_frame(ubit_t *ra_bits, size_t ra_bits_size, const struct osmo_v110_decoded_frame *fr)
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{
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if (ra_bits_size < 36)
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return -EINVAL;
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/* X1 .. X2 */
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ra_bits[0 * 8 + 7] = fr->x_bits[0];
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ra_bits[3 * 8 + 3] = fr->x_bits[1];
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/* S1, S3, S4, S6, S8, S9 */
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ra_bits[0 * 8 + 3] = fr->s_bits[0];
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ra_bits[1 * 8 + 3] = fr->s_bits[2];
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ra_bits[1 * 8 + 7] = fr->s_bits[3];
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ra_bits[2 * 8 + 7] = fr->s_bits[5];
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ra_bits[3 * 8 + 7] = fr->s_bits[7];
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ra_bits[4 * 8 + 3] = fr->s_bits[8];
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/* E1 .. E3 are ignored */
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/* E4 .. E7 */
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memcpy(ra_bits + 2 * 8 + 0, fr->e_bits+3, 4);
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/* D-bits */
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unsigned int d_idx = 0;
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ra_bits[0 * 8 + 0] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[0 * 8 + 1] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[0 * 8 + 2] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[0 * 8 + 4] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[0 * 8 + 5] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[0 * 8 + 6] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[1 * 8 + 0] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[1 * 8 + 1] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[1 * 8 + 2] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[1 * 8 + 4] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[1 * 8 + 5] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[1 * 8 + 6] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[2 * 8 + 4] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[2 * 8 + 5] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[2 * 8 + 6] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[3 * 8 + 0] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[3 * 8 + 1] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[3 * 8 + 2] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[3 * 8 + 4] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[3 * 8 + 5] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[3 * 8 + 6] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[4 * 8 + 0] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[4 * 8 + 1] = fr->d_bits[d_idx]; d_idx += 2;
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ra_bits[4 * 8 + 2] = fr->d_bits[d_idx]; d_idx += 2;
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OSMO_ASSERT(d_idx == 48);
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return 36;
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}
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/*! Print a encoded "CSD modififed V.110" frame in the same table-like structure as the spec.
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* \param outf output FILE stream to which to dump
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* \param[in] fr unpacked bits to dump
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* \param[in] in_len length of unpacked bits available at fr. */
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void osmo_csd_ubit_dump(FILE *outf, const ubit_t *fr, size_t in_len)
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{
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switch (in_len) {
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case 60:
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for (unsigned int septet = 0; septet < 9; septet++) {
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if (septet < 8) {
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fprintf(outf, "%d\t%d\t%d\t%d\t%d\t%d\t%d\n", fr[septet * 7 + 0],
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fr[septet * 7 + 1], fr[septet * 7 + 2], fr[septet * 7 + 3],
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fr[septet * 7 + 4], fr[septet * 7 + 5], fr[septet*7 + 6]);
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} else {
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fprintf(outf, "%d\t%d\t%d\t%d\n", fr[septet * 7 + 0],
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fr[septet * 7 + 1], fr[septet * 7 + 2], fr[septet * 7 + 3]);
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}
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}
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break;
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case 36:
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for (unsigned int octet = 0; octet < 5; octet++) {
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if (octet < 4) {
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fprintf(outf, "%d\t%d\t%d\t%d\t%d\t%d\t%d\t%d\n",
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fr[octet * 8 + 0], fr[octet * 8 + 1], fr[octet * 8 + 2],
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fr[octet * 8 + 3], fr[octet * 8 + 4], fr[octet * 8 + 5],
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fr[octet * 8 + 6], fr[octet * 8 + 7]);
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} else {
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fprintf(outf, "%d\t%d\t%d\t%d\n", fr[octet * 8 + 0],
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fr[octet * 8 + 1], fr[octet * 8 + 2], fr[octet * 8 + 3]);
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}
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}
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break;
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default:
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fprintf(outf, "invalid input data length: %zu\n", in_len);
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}
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}
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