diff options
Diffstat (limited to 'src/gsm/gsm44021.c')
| -rw-r--r-- | src/gsm/gsm44021.c | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/src/gsm/gsm44021.c b/src/gsm/gsm44021.c new file mode 100644 index 00000000..5e9d5ab8 --- /dev/null +++ b/src/gsm/gsm44021.c @@ -0,0 +1,303 @@ +/************************************************************************* + * 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); + } +} |