osmocom
/
libosmocore
mirror of https://gerrit.osmocom.org/libosmocore
11
0
Fork 0
Code Issues Releases Wiki Activity
libosmocore/src/gsm/gsm44021.c

304 lines
11 KiB
C
Raw Permalink Blame History

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