diff options
Diffstat (limited to 'lib/decoding/osmocom/coding/gsm0503_coding.c')
-rw-r--r-- | lib/decoding/osmocom/coding/gsm0503_coding.c | 1753 |
1 files changed, 1753 insertions, 0 deletions
diff --git a/lib/decoding/osmocom/coding/gsm0503_coding.c b/lib/decoding/osmocom/coding/gsm0503_coding.c new file mode 100644 index 0000000..afbba88 --- /dev/null +++ b/lib/decoding/osmocom/coding/gsm0503_coding.c @@ -0,0 +1,1753 @@ +/* + * (C) 2013 by Andreas Eversberg <jolly@eversberg.eu> + * (C) 2015 by Alexander Chemeris <Alexander.Chemeris@fairwaves.co> + * (C) 2016 by Tom Tsou <tom.tsou@ettus.com> + * + * All Rights Reserved + * + * 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, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#include <stdio.h> +#include <stdint.h> +#include <string.h> +#include <stdlib.h> + +#ifdef __cplusplus +extern "C" { +#endif + +#include <osmocom/core/bits.h> +#include <osmocom/core/conv.h> +#include <osmocom/core/utils.h> +#include <osmocom/core/crcgen.h> +#include <osmocom/core/endian.h> + +#include <osmocom/gsm/protocol/gsm_04_08.h> +#include "gsm0503.h" +#include <osmocom/codec/codec.h> + +#include "gsm0503_interleaving.h" +#include "gsm0503_mapping.h" +#include "gsm0503_tables.h" +#include "gsm0503_coding.h" +#include "gsm0503_parity.h" + +#ifdef __cplusplus +} +#endif + + +/* + * EGPRS coding limits + */ + +/* Max header size with parity bits */ +#define EGPRS_HDR_UPP_MAX 54 + +/* Max encoded header size */ +#define EGPRS_HDR_C_MAX 162 + +/* Max punctured header size */ +#define EGPRS_HDR_HC_MAX 160 + +/* Max data block size with parity bits */ +#define EGPRS_DATA_U_MAX 612 + +/* Max encoded data block size */ +#define EGPRS_DATA_C_MAX 1836 + +/* Max single block punctured data size */ +#define EGPRS_DATA_DC_MAX 1248 + +/* Dual block punctured data size */ +#define EGPRS_DATA_C1 612 +#define EGPRS_DATA_C2 EGPRS_DATA_C1 + +/* TS 101318 Chapter 5.1: 260 bits + 4bit sig */ +#define GSM_FR_BYTES 33 +/* TS 101318 Chapter 5.2: 112 bits, no sig */ +#define GSM_HR_BYTES 14 +/* TS 101318 Chapter 5.3: 244 bits + 4bit sig */ +#define GSM_EFR_BYTES 31 + +struct gsm0503_mcs_code { + uint8_t mcs; + uint8_t usf_len; + + /* Header coding */ + uint8_t hdr_len; + uint8_t hdr_code_len; + uint8_t hdr_punc_len; + const struct osmo_conv_code *hdr_conv; + const uint8_t *hdr_punc; + + /* Data coding */ + uint16_t data_len; + uint16_t data_code_len; + uint16_t data_punc_len; + const struct osmo_conv_code *data_conv; + const uint8_t *data_punc[3]; +}; + +static int osmo_conv_decode_ber(const struct osmo_conv_code *code, + const sbit_t *input, ubit_t *output, + int *n_errors, int *n_bits_total) +{ + int res, i, coded_len; + ubit_t recoded[EGPRS_DATA_C_MAX]; + + res = osmo_conv_decode(code, input, output); + + if (n_bits_total || n_errors) { + coded_len = osmo_conv_encode(code, output, recoded); + OSMO_ASSERT(sizeof(recoded) / sizeof(recoded[0]) >= coded_len); + } + + /* Count bit errors */ + if (n_errors) { + *n_errors = 0; + for (i = 0; i < coded_len; i++) { + if (!((recoded[i] && input[i] < 0) || + (!recoded[i] && input[i] > 0)) ) + *n_errors += 1; + } + } + + if (n_bits_total) + *n_bits_total = coded_len; + + return res; +} + +static int _xcch_decode_cB(uint8_t *l2_data, sbit_t *cB, + int *n_errors, int *n_bits_total) +{ + ubit_t conv[224]; + int rv; + + osmo_conv_decode_ber(&gsm0503_xcch, cB, + conv, n_errors, n_bits_total); + + rv = osmo_crc64gen_check_bits(&gsm0503_fire_crc40, + conv, 184, conv + 184); + if (rv) + return -1; + + osmo_ubit2pbit_ext(l2_data, 0, conv, 0, 184, 1); + + return 0; +} + +static int _xcch_encode_cB(ubit_t *cB, uint8_t *l2_data) +{ + ubit_t conv[224]; + + osmo_pbit2ubit_ext(conv, 0, l2_data, 0, 184, 1); + + osmo_crc64gen_set_bits(&gsm0503_fire_crc40, conv, 184, conv + 184); + + osmo_conv_encode(&gsm0503_xcch, conv, cB); + + return 0; +} + +/* + * GSM xCCH block transcoding + */ +int gsm0503_xcch_decode(uint8_t *l2_data, sbit_t *bursts, + int *n_errors, int *n_bits_total) +{ + sbit_t iB[456], cB[456]; + int i; + + for (i = 0; i < 4; i++) + gsm0503_xcch_burst_unmap(&iB[i * 114], &bursts[i * 116], NULL, NULL); + + gsm0503_xcch_deinterleave(cB, iB); + + return _xcch_decode_cB(l2_data, cB, n_errors, n_bits_total); +} + +int gsm0503_xcch_encode(ubit_t *bursts, uint8_t *l2_data) +{ + ubit_t iB[456], cB[456], hl = 1, hn = 1; + int i; + + _xcch_encode_cB(cB, l2_data); + + gsm0503_xcch_interleave(cB, iB); + + for (i = 0; i < 4; i++) + gsm0503_xcch_burst_map(&iB[i * 114], &bursts[i * 116], &hl, &hn); + + return 0; +} + + + +/* + * GSM PDTCH block transcoding + */ + +int gsm0503_pdtch_decode(uint8_t *l2_data, sbit_t *bursts, uint8_t *usf_p, + int *n_errors, int *n_bits_total) +{ + sbit_t iB[456], cB[676], hl_hn[8]; + ubit_t conv[456]; + int i, j, k, rv, best = 0, cs = 0, usf = 0; /* make GCC happy */ + + for (i = 0; i < 4; i++) + gsm0503_xcch_burst_unmap(&iB[i * 114], &bursts[i * 116], + hl_hn + i * 2, hl_hn + i * 2 + 1); + + for (i = 0; i < 4; i++) { + for (j = 0, k = 0; j < 8; j++) + k += abs(((int)gsm0503_pdtch_hl_hn_sbit[i][j]) - ((int)hl_hn[j])); + + if (i == 0 || k < best) { + best = k; + cs = i+1; + } + } + + gsm0503_xcch_deinterleave(cB, iB); + + switch (cs) { + case 1: + osmo_conv_decode_ber(&gsm0503_xcch, cB, + conv, n_errors, n_bits_total); + + rv = osmo_crc64gen_check_bits(&gsm0503_fire_crc40, + conv, 184, conv + 184); + if (rv) + return -1; + + osmo_ubit2pbit_ext(l2_data, 0, conv, 0, 184, 1); + + return 23; + case 2: + for (i = 587, j = 455; i >= 0; i--) { + if (!gsm0503_puncture_cs2[i]) + cB[i] = cB[j--]; + else + cB[i] = 0; + } + + osmo_conv_decode_ber(&gsm0503_cs2, cB, + conv, n_errors, n_bits_total); + + for (i = 0; i < 8; i++) { + for (j = 0, k = 0; j < 6; j++) + k += abs(((int)gsm0503_usf2six[i][j]) - ((int)conv[j])); + + if (i == 0 || k < best) { + best = k; + usf = i; + } + } + + conv[3] = usf & 1; + conv[4] = (usf >> 1) & 1; + conv[5] = (usf >> 2) & 1; + if (usf_p) + *usf_p = usf; + + rv = osmo_crc16gen_check_bits(&gsm0503_cs234_crc16, + conv + 3, 271, conv + 3 + 271); + if (rv) + return -1; + + osmo_ubit2pbit_ext(l2_data, 0, conv, 3, 271, 1); + + return 34; + case 3: + for (i = 675, j = 455; i >= 0; i--) { + if (!gsm0503_puncture_cs3[i]) + cB[i] = cB[j--]; + else + cB[i] = 0; + } + + osmo_conv_decode_ber(&gsm0503_cs3, cB, + conv, n_errors, n_bits_total); + + for (i = 0; i < 8; i++) { + for (j = 0, k = 0; j < 6; j++) + k += abs(((int)gsm0503_usf2six[i][j]) - ((int)conv[j])); + + if (i == 0 || k < best) { + best = k; + usf = i; + } + } + + conv[3] = usf & 1; + conv[4] = (usf >> 1) & 1; + conv[5] = (usf >> 2) & 1; + if (usf_p) + *usf_p = usf; + + rv = osmo_crc16gen_check_bits(&gsm0503_cs234_crc16, + conv + 3, 315, conv + 3 + 315); + if (rv) + return -1; + + osmo_ubit2pbit_ext(l2_data, 0, conv, 3, 315, 1); + + return 40; + case 4: + for (i = 12; i < 456; i++) + conv[i] = (cB[i] < 0) ? 1 : 0; + + for (i = 0; i < 8; i++) { + for (j = 0, k = 0; j < 12; j++) + k += abs(((int)gsm0503_usf2twelve_sbit[i][j]) - ((int)cB[j])); + + if (i == 0 || k < best) { + best = k; + usf = i; + } + } + + conv[9] = usf & 1; + conv[10] = (usf >> 1) & 1; + conv[11] = (usf >> 2) & 1; + if (usf_p) + *usf_p = usf; + + rv = osmo_crc16gen_check_bits(&gsm0503_cs234_crc16, + conv + 9, 431, conv + 9 + 431); + if (rv) { + *n_bits_total = 456 - 12; + *n_errors = *n_bits_total; + return -1; + } + + *n_bits_total = 456 - 12; + *n_errors = 0; + + osmo_ubit2pbit_ext(l2_data, 0, conv, 9, 431, 1); + + return 54; + default: + *n_bits_total = 0; + *n_errors = 0; + break; + } + + return -1; +} + +int gsm0503_pdtch_encode(ubit_t *bursts, uint8_t *l2_data, uint8_t l2_len) +{ + ubit_t iB[456], cB[676]; + const ubit_t *hl_hn; + ubit_t conv[334]; + int i, j, usf; + + switch (l2_len) { + case 23: + osmo_pbit2ubit_ext(conv, 0, l2_data, 0, 184, 1); + + osmo_crc64gen_set_bits(&gsm0503_fire_crc40, conv, 184, conv + 184); + + osmo_conv_encode(&gsm0503_xcch, conv, cB); + + hl_hn = gsm0503_pdtch_hl_hn_ubit[0]; + + break; + case 34: + osmo_pbit2ubit_ext(conv, 3, l2_data, 0, 271, 1); + usf = l2_data[0] & 0x7; + + osmo_crc16gen_set_bits(&gsm0503_cs234_crc16, conv + 3, + 271, conv + 3 + 271); + + memcpy(conv, gsm0503_usf2six[usf], 6); + + osmo_conv_encode(&gsm0503_cs2, conv, cB); + + for (i = 0, j = 0; i < 588; i++) + if (!gsm0503_puncture_cs2[i]) + cB[j++] = cB[i]; + + hl_hn = gsm0503_pdtch_hl_hn_ubit[1]; + + break; + case 40: + osmo_pbit2ubit_ext(conv, 3, l2_data, 0, 315, 1); + usf = l2_data[0] & 0x7; + + osmo_crc16gen_set_bits(&gsm0503_cs234_crc16, conv + 3, + 315, conv + 3 + 315); + + memcpy(conv, gsm0503_usf2six[usf], 6); + + osmo_conv_encode(&gsm0503_cs3, conv, cB); + + for (i = 0, j = 0; i < 676; i++) + if (!gsm0503_puncture_cs3[i]) + cB[j++] = cB[i]; + + hl_hn = gsm0503_pdtch_hl_hn_ubit[2]; + + break; + case 54: + osmo_pbit2ubit_ext(cB, 9, l2_data, 0, 431, 1); + usf = l2_data[0] & 0x7; + + osmo_crc16gen_set_bits(&gsm0503_cs234_crc16, cB + 9, + 431, cB + 9 + 431); + + memcpy(cB, gsm0503_usf2twelve_ubit[usf], 12); + + hl_hn = gsm0503_pdtch_hl_hn_ubit[3]; + + break; + default: + return -1; + } + + gsm0503_xcch_interleave(cB, iB); + + for (i = 0; i < 4; i++) { + gsm0503_xcch_burst_map(&iB[i * 114], &bursts[i * 116], + hl_hn + i * 2, hl_hn + i * 2 + 1); + } + + return GSM0503_GPRS_BURSTS_NBITS; +} + +/* + * GSM TCH/F FR/EFR transcoding + */ + +static void tch_fr_reassemble(uint8_t *tch_data, + ubit_t *b_bits, int net_order) +{ + int i, j, k, l, o; + + tch_data[0] = 0xd << 4; + memset(tch_data + 1, 0, 32); + + if (net_order) { + for (i = 0, j = 4; i < 260; i++, j++) + tch_data[j >> 3] |= (b_bits[i] << (7 - (j & 7))); + + return; + } + + /* reassemble d-bits */ + i = 0; /* counts bits */ + j = 4; /* counts output bits */ + k = gsm0503_gsm_fr_map[0]-1; /* current number bit in element */ + l = 0; /* counts element bits */ + o = 0; /* offset input bits */ + while (i < 260) { + tch_data[j >> 3] |= (b_bits[k + o] << (7 - (j & 7))); + if (--k < 0) { + o += gsm0503_gsm_fr_map[l]; + k = gsm0503_gsm_fr_map[++l]-1; + } + i++; + j++; + } +} + +static void tch_fr_disassemble(ubit_t *b_bits, + uint8_t *tch_data, int net_order) +{ + int i, j, k, l, o; + + if (net_order) { + for (i = 0, j = 4; i < 260; i++, j++) + b_bits[i] = (tch_data[j >> 3] >> (7 - (j & 7))) & 1; + + return; + } + + i = 0; /* counts bits */ + j = 4; /* counts input bits */ + k = gsm0503_gsm_fr_map[0] - 1; /* current number bit in element */ + l = 0; /* counts element bits */ + o = 0; /* offset output bits */ + while (i < 260) { + b_bits[k + o] = (tch_data[j >> 3] >> (7 - (j & 7))) & 1; + if (--k < 0) { + o += gsm0503_gsm_fr_map[l]; + k = gsm0503_gsm_fr_map[++l] - 1; + } + i++; + j++; + } +} + +static void tch_hr_reassemble(uint8_t *tch_data, ubit_t *b_bits) +{ + int i, j; + + tch_data[0] = 0x00; /* F = 0, FT = 000 */ + memset(tch_data + 1, 0, 14); + + for (i = 0, j = 8; i < 112; i++, j++) + tch_data[j >> 3] |= (b_bits[i] << (7 - (j & 7))); +} + +static void tch_hr_disassemble(ubit_t *b_bits, uint8_t *tch_data) +{ + int i, j; + + for (i = 0, j = 8; i < 112; i++, j++) + b_bits[i] = (tch_data[j >> 3] >> (7 - (j & 7))) & 1; +} + +static void tch_efr_reassemble(uint8_t *tch_data, ubit_t *b_bits) +{ + int i, j; + + tch_data[0] = 0xc << 4; + memset(tch_data + 1, 0, 30); + + for (i = 0, j = 4; i < 244; i++, j++) + tch_data[j >> 3] |= (b_bits[i] << (7 - (j & 7))); +} + +static void tch_efr_disassemble(ubit_t *b_bits, uint8_t *tch_data) +{ + int i, j; + + for (i = 0, j = 4; i < 244; i++, j++) + b_bits[i] = (tch_data[j >> 3] >> (7 - (j & 7))) & 1; +} + +static void tch_amr_reassemble(uint8_t *tch_data, ubit_t *d_bits, int len) +{ + int i, j; + + memset(tch_data, 0, (len + 7) >> 3); + + for (i = 0, j = 0; i < len; i++, j++) + tch_data[j >> 3] |= (d_bits[i] << (7 - (j & 7))); +} + +static void tch_amr_disassemble(ubit_t *d_bits, uint8_t *tch_data, int len) +{ + int i, j; + + for (i = 0, j = 0; i < len; i++, j++) + d_bits[i] = (tch_data[j >> 3] >> (7 - (j & 7))) & 1; +} + +static void tch_fr_d_to_b(ubit_t *b_bits, ubit_t *d_bits) +{ + int i; + + for (i = 0; i < 260; i++) + b_bits[gsm610_bitorder[i]] = d_bits[i]; +} + +static void tch_fr_b_to_d(ubit_t *d_bits, ubit_t *b_bits) +{ + int i; + + for (i = 0; i < 260; i++) + d_bits[i] = b_bits[gsm610_bitorder[i]]; +} + +static void tch_hr_d_to_b(ubit_t *b_bits, ubit_t *d_bits) +{ + int i; + + const uint16_t *map; + + if (!d_bits[93] && !d_bits[94]) + map = gsm620_unvoiced_bitorder; + else + map = gsm620_voiced_bitorder; + + for (i = 0; i < 112; i++) + b_bits[map[i]] = d_bits[i]; +} + +static void tch_hr_b_to_d(ubit_t *d_bits, ubit_t *b_bits) +{ + int i; + const uint16_t *map; + + if (!b_bits[34] && !b_bits[35]) + map = gsm620_unvoiced_bitorder; + else + map = gsm620_voiced_bitorder; + + for (i = 0; i < 112; i++) + d_bits[i] = b_bits[map[i]]; +} + +static void tch_efr_d_to_w(ubit_t *b_bits, ubit_t *d_bits) +{ + int i; + + for (i = 0; i < 260; i++) + b_bits[gsm660_bitorder[i]] = d_bits[i]; +} + +static void tch_efr_w_to_d(ubit_t *d_bits, ubit_t *b_bits) +{ + int i; + + for (i = 0; i < 260; i++) + d_bits[i] = b_bits[gsm660_bitorder[i]]; +} + +static void tch_efr_protected(ubit_t *s_bits, ubit_t *b_bits) +{ + int i; + + for (i = 0; i < 65; i++) + b_bits[i] = s_bits[gsm0503_gsm_efr_protected_bits[i] - 1]; +} + +static void tch_fr_unreorder(ubit_t *d, ubit_t *p, ubit_t *u) +{ + int i; + + for (i = 0; i < 91; i++) { + d[i << 1] = u[i]; + d[(i << 1) + 1] = u[184 - i]; + } + + for (i = 0; i < 3; i++) + p[i] = u[91 + i]; +} + +static void tch_fr_reorder(ubit_t *u, ubit_t *d, ubit_t *p) +{ + int i; + + for (i = 0; i < 91; i++) { + u[i] = d[i << 1]; + u[184 - i] = d[(i << 1) + 1]; + } + + for (i = 0; i < 3; i++) + u[91 + i] = p[i]; +} + +static void tch_hr_unreorder(ubit_t *d, ubit_t *p, ubit_t *u) +{ + memcpy(d, u, 95); + memcpy(p, u + 95, 3); +} + +static void tch_hr_reorder(ubit_t *u, ubit_t *d, ubit_t *p) +{ + memcpy(u, d, 95); + memcpy(u + 95, p, 3); +} + +static void tch_efr_reorder(ubit_t *w, ubit_t *s, ubit_t *p) +{ + memcpy(w, s, 71); + w[71] = w[72] = s[69]; + memcpy(w + 73, s + 71, 50); + w[123] = w[124] = s[119]; + memcpy(w + 125, s + 121, 53); + w[178] = w[179] = s[172]; + memcpy(w + 180, s + 174, 50); + w[230] = w[231] = s[222]; + memcpy(w + 232, s + 224, 20); + memcpy(w + 252, p, 8); +} + +static void tch_efr_unreorder(ubit_t *s, ubit_t *p, ubit_t *w) +{ + int sum; + + memcpy(s, w, 71); + sum = s[69] + w[71] + w[72]; + s[69] = (sum > 2); + memcpy(s + 71, w + 73, 50); + sum = s[119] + w[123] + w[124]; + s[119] = (sum > 2); + memcpy(s + 121, w + 125, 53); + sum = s[172] + w[178] + w[179]; + s[172] = (sum > 2); + memcpy(s + 174, w + 180, 50); + sum = s[220] + w[230] + w[231]; + s[222] = (sum > 2); + memcpy(s + 224, w + 232, 20); + memcpy(p, w + 252, 8); +} + +static void tch_amr_merge(ubit_t *u, ubit_t *d, ubit_t *p, int len, int prot) +{ + memcpy(u, d, prot); + memcpy(u + prot, p, 6); + memcpy(u + prot + 6, d + prot, len - prot); +} + +static void tch_amr_unmerge(ubit_t *d, ubit_t *p, + ubit_t *u, int len, int prot) +{ + memcpy(d, u, prot); + memcpy(p, u+prot, 6); + memcpy(d + prot, u + prot + 6, len - prot); +} + +int gsm0503_tch_fr_decode(uint8_t *tch_data, sbit_t *bursts, + int net_order, int efr, int *n_errors, int *n_bits_total) +{ + sbit_t iB[912], cB[456], h; + ubit_t conv[185], s[244], w[260], b[65], d[260], p[8]; + int i, rv, len, steal = 0; + + for (i=0; i<8; i++) { + gsm0503_tch_burst_unmap(&iB[i * 114], + &bursts[i * 116], &h, i >> 2); + steal -= h; + } + + gsm0503_tch_fr_deinterleave(cB, iB); + + if (steal > 0) { + rv = _xcch_decode_cB(tch_data, cB, n_errors, n_bits_total); + if (rv) { + /* Error decoding FACCH frame */ + return -1; + } + + return 23; + } + + osmo_conv_decode_ber(&gsm0503_tch_fr, cB, conv, n_errors, n_bits_total); + + tch_fr_unreorder(d, p, conv); + + for (i = 0; i < 78; i++) + d[i + 182] = (cB[i + 378] < 0) ? 1 : 0; + + rv = osmo_crc8gen_check_bits(&gsm0503_tch_fr_crc3, d, 50, p); + if (rv) { + /* Error checking CRC8 for the FR part of an EFR/FR frame */ + return -1; + } + + if (efr) { + tch_efr_d_to_w(w, d); + + tch_efr_unreorder(s, p, w); + + tch_efr_protected(s, b); + + rv = osmo_crc8gen_check_bits(&gsm0503_tch_efr_crc8, b, 65, p); + if (rv) { + /* Error checking CRC8 for the EFR part of an EFR frame */ + return -1; + } + + tch_efr_reassemble(tch_data, s); + + len = GSM_EFR_BYTES; + } else { + tch_fr_d_to_b(w, d); + + tch_fr_reassemble(tch_data, w, net_order); + + len = GSM_FR_BYTES; + } + + return len; +} + +int gsm0503_tch_fr_encode(ubit_t *bursts, uint8_t *tch_data, + int len, int net_order) +{ + ubit_t iB[912], cB[456], h; + ubit_t conv[185], w[260], b[65], s[244], d[260], p[8]; + int i; + + switch (len) { + case GSM_EFR_BYTES: /* TCH EFR */ + + tch_efr_disassemble(s, tch_data); + + tch_efr_protected(s, b); + + osmo_crc8gen_set_bits(&gsm0503_tch_efr_crc8, b, 65, p); + + tch_efr_reorder(w, s, p); + + tch_efr_w_to_d(d, w); + + goto coding_efr_fr; + case GSM_FR_BYTES: /* TCH FR */ + tch_fr_disassemble(w, tch_data, net_order); + + tch_fr_b_to_d(d, w); + +coding_efr_fr: + osmo_crc8gen_set_bits(&gsm0503_tch_fr_crc3, d, 50, p); + + tch_fr_reorder(conv, d, p); + + memcpy(cB + 378, d + 182, 78); + + osmo_conv_encode(&gsm0503_tch_fr, conv, cB); + + h = 0; + + break; + case GSM_MACBLOCK_LEN: /* FACCH */ + _xcch_encode_cB(cB, tch_data); + + h = 1; + + break; + default: + return -1; + } + + gsm0503_tch_fr_interleave(cB, iB); + + for (i = 0; i < 8; i++) { + gsm0503_tch_burst_map(&iB[i * 114], + &bursts[i * 116], &h, i >> 2); + } + + return 0; +} + +int gsm0503_tch_hr_decode(uint8_t *tch_data, sbit_t *bursts, int odd, + int *n_errors, int *n_bits_total) +{ + sbit_t iB[912], cB[456], h; + ubit_t conv[98], b[112], d[112], p[3]; + int i, rv, steal = 0; + + /* Only unmap the stealing bits */ + if (!odd) { + for (i = 0; i < 4; i++) { + gsm0503_tch_burst_unmap(NULL, &bursts[i * 116], &h, 0); + steal -= h; + } + + for (i = 2; i < 5; i++) { + gsm0503_tch_burst_unmap(NULL, &bursts[i * 116], &h, 1); + steal -= h; + } + } + + /* If we found a stole FACCH, but only at correct alignment */ + if (steal > 0) { + for (i = 0; i < 6; i++) { + gsm0503_tch_burst_unmap(&iB[i * 114], + &bursts[i * 116], NULL, i >> 2); + } + + for (i = 2; i < 4; i++) { + gsm0503_tch_burst_unmap(&iB[i * 114 + 456], + &bursts[i * 116], NULL, 1); + } + + gsm0503_tch_fr_deinterleave(cB, iB); + + rv = _xcch_decode_cB(tch_data, cB, n_errors, n_bits_total); + if (rv) { + /* Error decoding FACCH frame */ + return -1; + } + + return GSM_MACBLOCK_LEN; + } + + for (i = 0; i < 4; i++) { + gsm0503_tch_burst_unmap(&iB[i * 114], + &bursts[i * 116], NULL, i >> 1); + } + + gsm0503_tch_hr_deinterleave(cB, iB); + + osmo_conv_decode_ber(&gsm0503_tch_hr, cB, conv, n_errors, n_bits_total); + + tch_hr_unreorder(d, p, conv); + + for (i = 0; i < 17; i++) + d[i + 95] = (cB[i + 211] < 0) ? 1 : 0; + + rv = osmo_crc8gen_check_bits(&gsm0503_tch_fr_crc3, d + 73, 22, p); + if (rv) { + /* Error checking CRC8 for an HR frame */ + return -1; + } + + tch_hr_d_to_b(b, d); + + tch_hr_reassemble(tch_data, b); + + return 15; +} + +int gsm0503_tch_hr_encode(ubit_t *bursts, uint8_t *tch_data, int len) +{ + ubit_t iB[912], cB[456], h; + ubit_t conv[98], b[112], d[112], p[3]; + int i; + + switch (len) { + case 15: /* TCH HR */ + tch_hr_disassemble(b, tch_data); + + tch_hr_b_to_d(d, b); + + osmo_crc8gen_set_bits(&gsm0503_tch_fr_crc3, d + 73, 22, p); + + tch_hr_reorder(conv, d, p); + + osmo_conv_encode(&gsm0503_tch_hr, conv, cB); + + memcpy(cB + 211, d + 95, 17); + + h = 0; + + gsm0503_tch_hr_interleave(cB, iB); + + for (i = 0; i < 4; i++) { + gsm0503_tch_burst_map(&iB[i * 114], + &bursts[i * 116], &h, i >> 1); + } + + break; + case GSM_MACBLOCK_LEN: /* FACCH */ + _xcch_encode_cB(cB, tch_data); + + h = 1; + + gsm0503_tch_fr_interleave(cB, iB); + + for (i=0; i<6; i++) { + gsm0503_tch_burst_map(&iB[i * 114], + &bursts[i * 116], &h, i >> 2); + } + + for (i=2; i<4; i++) { + gsm0503_tch_burst_map(&iB[i * 114 + 456], + &bursts[i * 116], &h, 1); + } + + break; + default: + return -1; + } + + return 0; +} + +int gsm0503_tch_afs_decode(uint8_t *tch_data, sbit_t *bursts, + int codec_mode_req, uint8_t *codec, int codecs, uint8_t *ft, + uint8_t *cmr, int *n_errors, int *n_bits_total) +{ + sbit_t iB[912], cB[456], h; + ubit_t d[244], p[6], conv[250]; + int i, j, k, best = 0, rv, len, steal = 0, id = 0; + *n_errors = 0; *n_bits_total = 0; + + for (i=0; i<8; i++) { + gsm0503_tch_burst_unmap(&iB[i * 114], &bursts[i * 116], &h, i >> 2); + steal -= h; + } + + gsm0503_tch_fr_deinterleave(cB, iB); + + if (steal > 0) { + rv = _xcch_decode_cB(tch_data, cB, n_errors, n_bits_total); + if (rv) { + /* Error decoding FACCH frame */ + return -1; + } + + return GSM_MACBLOCK_LEN; + } + + for (i = 0; i < 4; i++) { + for (j = 0, k = 0; j < 8; j++) + k += abs(((int)gsm0503_afs_ic_sbit[i][j]) - ((int)cB[j])); + + if (i == 0 || k < best) { + best = k; + id = i; + } + } + + /* Check if indicated codec fits into range of codecs */ + if (id >= codecs) { + /* Codec mode out of range, return id */ + return id; + } + + switch ((codec_mode_req) ? codec[*ft] : codec[id]) { + case 7: /* TCH/AFS12.2 */ + osmo_conv_decode_ber(&gsm0503_tch_afs_12_2, cB + 8, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 244, 81); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 81, p); + if (rv) { + /* Error checking CRC8 for an AMR 12.2 frame */ + return -1; + } + + tch_amr_reassemble(tch_data, d, 244); + + len = 31; + + break; + case 6: /* TCH/AFS10.2 */ + osmo_conv_decode_ber(&gsm0503_tch_afs_10_2, cB + 8, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 204, 65); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 65, p); + if (rv) { + /* Error checking CRC8 for an AMR 10.2 frame */ + return -1; + } + + tch_amr_reassemble(tch_data, d, 204); + + len = 26; + + break; + case 5: /* TCH/AFS7.95 */ + osmo_conv_decode_ber(&gsm0503_tch_afs_7_95, cB + 8, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 159, 75); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 75, p); + if (rv) { + /* Error checking CRC8 for an AMR 7.95 frame */ + return -1; + } + + tch_amr_reassemble(tch_data, d, 159); + + len = 20; + + break; + case 4: /* TCH/AFS7.4 */ + osmo_conv_decode_ber(&gsm0503_tch_afs_7_4, cB + 8, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 148, 61); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 61, p); + if (rv) { + /* Error checking CRC8 for an AMR 7.4 frame */ + return -1; + } + + tch_amr_reassemble(tch_data, d, 148); + + len = 19; + + break; + case 3: /* TCH/AFS6.7 */ + osmo_conv_decode_ber(&gsm0503_tch_afs_6_7, cB + 8, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 134, 55); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 55, p); + if (rv) { + /* Error checking CRC8 for an AMR 6.7 frame */ + return -1; + } + + tch_amr_reassemble(tch_data, d, 134); + + len = 17; + + break; + case 2: /* TCH/AFS5.9 */ + osmo_conv_decode_ber(&gsm0503_tch_afs_5_9, cB + 8, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 118, 55); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 55, p); + if (rv) { + /* Error checking CRC8 for an AMR 5.9 frame */ + return -1; + } + + tch_amr_reassemble(tch_data, d, 118); + + len = 15; + + break; + case 1: /* TCH/AFS5.15 */ + osmo_conv_decode_ber(&gsm0503_tch_afs_5_15, cB + 8, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 103, 49); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 49, p); + if (rv) { + /* Error checking CRC8 for an AMR 5.15 frame */ + return -1; + } + + tch_amr_reassemble(tch_data, d, 103); + + len = 13; + + break; + case 0: /* TCH/AFS4.75 */ + osmo_conv_decode_ber(&gsm0503_tch_afs_4_75, cB + 8, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 95, 39); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 39, p); + if (rv) { + /* Error checking CRC8 for an AMR 4.75 frame */ + return -1; + } + + tch_amr_reassemble(tch_data, d, 95); + + len = 12; + + break; + default: + /* Unknown frame type */ + *n_bits_total = 448; + *n_errors = *n_bits_total; + return -1; + } + + /* Change codec request / indication, if frame is valid */ + if (codec_mode_req) + *cmr = id; + else + *ft = id; + + return len; +} + +int gsm0503_tch_afs_encode(ubit_t *bursts, uint8_t *tch_data, int len, + int codec_mode_req, uint8_t *codec, int codecs, uint8_t ft, + uint8_t cmr) +{ + ubit_t iB[912], cB[456], h; + ubit_t d[244], p[6], conv[250]; + int i; + uint8_t id; + + if (len == GSM_MACBLOCK_LEN) { /* FACCH */ + _xcch_encode_cB(cB, tch_data); + + h = 1; + + goto facch; + } + + h = 0; + + if (codec_mode_req) { + if (cmr >= codecs) { + /* FIXME: CMR ID is not in codec list! */ + return -1; + } + id = cmr; + } else { + if (ft >= codecs) { + /* FIXME: FT ID is not in codec list! */ + return -1; + } + id = ft; + } + + switch (codec[ft]) { + case 7: /* TCH/AFS12.2 */ + if (len != 31) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 244); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 81, p); + + tch_amr_merge(conv, d, p, 244, 81); + + osmo_conv_encode(&gsm0503_tch_afs_12_2, conv, cB + 8); + + break; + case 6: /* TCH/AFS10.2 */ + if (len != 26) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 204); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 65, p); + + tch_amr_merge(conv, d, p, 204, 65); + + osmo_conv_encode(&gsm0503_tch_afs_10_2, conv, cB + 8); + + break; + case 5: /* TCH/AFS7.95 */ + if (len != 20) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 159); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 75, p); + + tch_amr_merge(conv, d, p, 159, 75); + + osmo_conv_encode(&gsm0503_tch_afs_7_95, conv, cB + 8); + + break; + case 4: /* TCH/AFS7.4 */ + if (len != 19) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 148); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 61, p); + + tch_amr_merge(conv, d, p, 148, 61); + + osmo_conv_encode(&gsm0503_tch_afs_7_4, conv, cB + 8); + + break; + case 3: /* TCH/AFS6.7 */ + if (len != 17) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 134); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 55, p); + + tch_amr_merge(conv, d, p, 134, 55); + + osmo_conv_encode(&gsm0503_tch_afs_6_7, conv, cB + 8); + + break; + case 2: /* TCH/AFS5.9 */ + if (len != 15) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 118); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 55, p); + + tch_amr_merge(conv, d, p, 118, 55); + + osmo_conv_encode(&gsm0503_tch_afs_5_9, conv, cB + 8); + + break; + case 1: /* TCH/AFS5.15 */ + if (len != 13) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 103); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 49, p); + + tch_amr_merge(conv, d, p, 103, 49); + + osmo_conv_encode(&gsm0503_tch_afs_5_15, conv, cB + 8); + + break; + case 0: /* TCH/AFS4.75 */ + if (len != 12) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 95); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 39, p); + + tch_amr_merge(conv, d, p, 95, 39); + + osmo_conv_encode(&gsm0503_tch_afs_4_75, conv, cB + 8); + + break; + default: + /* FIXME: FT %ft is not supported */ + return -1; + } + + memcpy(cB, gsm0503_afs_ic_ubit[id], 8); + +facch: + gsm0503_tch_fr_interleave(cB, iB); + + for (i = 0; i < 8; i++) { + gsm0503_tch_burst_map(&iB[i * 114], + &bursts[i * 116], &h, i >> 2); + } + + return 0; + +invalid_length: + /* FIXME: payload length %len does not comply with codec type %ft */ + return -1; +} + +int gsm0503_tch_ahs_decode(uint8_t *tch_data, sbit_t *bursts, int odd, + int codec_mode_req, uint8_t *codec, int codecs, uint8_t *ft, + uint8_t *cmr, int *n_errors, int *n_bits_total) +{ + sbit_t iB[912], cB[456], h; + ubit_t d[244], p[6], conv[135]; + int i, j, k, best = 0, rv, len, steal = 0, id = 0; + + /* only unmap the stealing bits */ + if (!odd) { + for (i = 0; i < 4; i++) { + gsm0503_tch_burst_unmap(NULL, &bursts[i * 116], &h, 0); + steal -= h; + } + for (i = 2; i < 5; i++) { + gsm0503_tch_burst_unmap(NULL, &bursts[i * 116], &h, 1); + steal -= h; + } + } + + /* if we found a stole FACCH, but only at correct alignment */ + if (steal > 0) { + for (i = 0; i < 6; i++) { + gsm0503_tch_burst_unmap(&iB[i * 114], + &bursts[i * 116], NULL, i >> 2); + } + + for (i = 2; i < 4; i++) { + gsm0503_tch_burst_unmap(&iB[i * 114 + 456], + &bursts[i * 116], NULL, 1); + } + + gsm0503_tch_fr_deinterleave(cB, iB); + + rv = _xcch_decode_cB(tch_data, cB, n_errors, n_bits_total); + if (rv) { + /* Error decoding FACCH frame */ + return -1; + } + + return GSM_MACBLOCK_LEN; + } + + for (i = 0; i < 4; i++) { + gsm0503_tch_burst_unmap(&iB[i * 114], + &bursts[i * 116], NULL, i >> 1); + } + + gsm0503_tch_hr_deinterleave(cB, iB); + + for (i = 0; i < 4; i++) { + for (j = 0, k = 0; j < 4; j++) + k += abs(((int)gsm0503_ahs_ic_sbit[i][j]) - ((int)cB[j])); + + if (i == 0 || k < best) { + best = k; + id = i; + } + } + + /* Check if indicated codec fits into range of codecs */ + if (id >= codecs) { + /* Codec mode out of range, return id */ + return id; + } + + switch ((codec_mode_req) ? codec[*ft] : codec[id]) { + case 5: /* TCH/AHS7.95 */ + osmo_conv_decode_ber(&gsm0503_tch_ahs_7_95, cB + 4, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 123, 67); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 67, p); + if (rv) { + /* Error checking CRC8 for an AMR 7.95 frame */ + return -1; + } + + for (i = 0; i < 36; i++) + d[i + 123] = (cB[i + 192] < 0) ? 1 : 0; + + tch_amr_reassemble(tch_data, d, 159); + + len = 20; + + break; + case 4: /* TCH/AHS7.4 */ + osmo_conv_decode_ber(&gsm0503_tch_ahs_7_4, cB + 4, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 120, 61); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 61, p); + if (rv) { + /* Error checking CRC8 for an AMR 7.4 frame */ + return -1; + } + + for (i = 0; i < 28; i++) + d[i + 120] = (cB[i + 200] < 0) ? 1 : 0; + + tch_amr_reassemble(tch_data, d, 148); + + len = 19; + + break; + case 3: /* TCH/AHS6.7 */ + osmo_conv_decode_ber(&gsm0503_tch_ahs_6_7, cB + 4, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 110, 55); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 55, p); + if (rv) { + /* Error checking CRC8 for an AMR 6.7 frame */ + return -1; + } + + for (i = 0; i < 24; i++) + d[i + 110] = (cB[i + 204] < 0) ? 1 : 0; + + tch_amr_reassemble(tch_data, d, 134); + + len = 17; + + break; + case 2: /* TCH/AHS5.9 */ + osmo_conv_decode_ber(&gsm0503_tch_ahs_5_9, cB + 4, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 102, 55); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 55, p); + if (rv) { + /* Error checking CRC8 for an AMR 5.9 frame */ + return -1; + } + + for (i = 0; i < 16; i++) + d[i + 102] = (cB[i + 212] < 0) ? 1 : 0; + + tch_amr_reassemble(tch_data, d, 118); + + len = 15; + + break; + case 1: /* TCH/AHS5.15 */ + osmo_conv_decode_ber(&gsm0503_tch_ahs_5_15, cB + 4, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 91, 49); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 49, p); + if (rv) { + /* Error checking CRC8 for an AMR 5.15 frame */ + return -1; + } + + for (i = 0; i < 12; i++) + d[i + 91] = (cB[i + 216] < 0) ? 1 : 0; + + tch_amr_reassemble(tch_data, d, 103); + + len = 13; + + break; + case 0: /* TCH/AHS4.75 */ + osmo_conv_decode_ber(&gsm0503_tch_ahs_4_75, cB + 4, + conv, n_errors, n_bits_total); + + tch_amr_unmerge(d, p, conv, 83, 39); + + rv = osmo_crc8gen_check_bits(&gsm0503_amr_crc6, d, 39, p); + if (rv) { + /* Error checking CRC8 for an AMR 4.75 frame */ + return -1; + } + + for (i = 0; i < 12; i++) + d[i + 83] = (cB[i + 216] < 0) ? 1 : 0; + + tch_amr_reassemble(tch_data, d, 95); + + len = 12; + + break; + default: + /* Unknown frame type */ + *n_bits_total = 159; + *n_errors = *n_bits_total; + return -1; + } + + /* Change codec request / indication, if frame is valid */ + if (codec_mode_req) + *cmr = id; + else + *ft = id; + + return len; +} + +int gsm0503_tch_ahs_encode(ubit_t *bursts, uint8_t *tch_data, int len, + int codec_mode_req, uint8_t *codec, int codecs, uint8_t ft, + uint8_t cmr) +{ + ubit_t iB[912], cB[456], h; + ubit_t d[244], p[6], conv[135]; + int i; + uint8_t id; + + if (len == GSM_MACBLOCK_LEN) { /* FACCH */ + _xcch_encode_cB(cB, tch_data); + + h = 1; + + gsm0503_tch_fr_interleave(cB, iB); + + for (i = 0; i < 6; i++) + gsm0503_tch_burst_map(&iB[i * 114], &bursts[i * 116], + &h, i >> 2); + for (i = 2; i < 4; i++) + gsm0503_tch_burst_map(&iB[i * 114 + 456], + &bursts[i * 116], &h, 1); + + return 0; + } + + h = 0; + + if (codec_mode_req) { + if (cmr >= codecs) { + /* FIXME: CMR ID %d not in codec list */ + return -1; + } + id = cmr; + } else { + if (ft >= codecs) { + /* FIXME: FT ID %d not in codec list */ + return -1; + } + id = ft; + } + + switch (codec[ft]) { + case 5: /* TCH/AHS7.95 */ + if (len != 20) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 159); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 67, p); + + tch_amr_merge(conv, d, p, 123, 67); + + osmo_conv_encode(&gsm0503_tch_ahs_7_95, conv, cB + 4); + + memcpy(cB + 192, d + 123, 36); + + break; + case 4: /* TCH/AHS7.4 */ + if (len != 19) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 148); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 61, p); + + tch_amr_merge(conv, d, p, 120, 61); + + osmo_conv_encode(&gsm0503_tch_ahs_7_4, conv, cB + 4); + + memcpy(cB + 200, d + 120, 28); + + break; + case 3: /* TCH/AHS6.7 */ + if (len != 17) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 134); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 55, p); + + tch_amr_merge(conv, d, p, 110, 55); + + osmo_conv_encode(&gsm0503_tch_ahs_6_7, conv, cB + 4); + + memcpy(cB + 204, d + 110, 24); + + break; + case 2: /* TCH/AHS5.9 */ + if (len != 15) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 118); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 55, p); + + tch_amr_merge(conv, d, p, 102, 55); + + osmo_conv_encode(&gsm0503_tch_ahs_5_9, conv, cB + 4); + + memcpy(cB + 212, d + 102, 16); + + break; + case 1: /* TCH/AHS5.15 */ + if (len != 13) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 103); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 49, p); + + tch_amr_merge(conv, d, p, 91, 49); + + osmo_conv_encode(&gsm0503_tch_ahs_5_15, conv, cB + 4); + + memcpy(cB + 216, d + 91, 12); + + break; + case 0: /* TCH/AHS4.75 */ + if (len != 12) + goto invalid_length; + + tch_amr_disassemble(d, tch_data, 95); + + osmo_crc8gen_set_bits(&gsm0503_amr_crc6, d, 39, p); + + tch_amr_merge(conv, d, p, 83, 39); + + osmo_conv_encode(&gsm0503_tch_ahs_4_75, conv, cB + 4); + + memcpy(cB + 216, d + 83, 12); + + break; + default: + /* FIXME: FT %ft is not supported */ + return -1; + } + + memcpy(cB, gsm0503_afs_ic_ubit[id], 4); + + gsm0503_tch_hr_interleave(cB, iB); + + for (i = 0; i < 4; i++) + gsm0503_tch_burst_map(&iB[i * 114], &bursts[i * 116], &h, i >> 1); + + return 0; + +invalid_length: + /* FIXME: payload length %len does not comply with codec type %ft */ + return -1; +} + +/* + * GSM RACH transcoding + */ + +/* + * GSM RACH apply BSIC to parity + * + * p(j) = p(j) xor b(j) j = 0, ..., 5 + * b(0) = MSB of PLMN colour code + * b(5) = LSB of BS colour code + */ +static int rach_apply_bsic(ubit_t *d, uint8_t bsic) +{ + int i; + + /* Apply it */ + for (i = 0; i < 6; i++) + d[8 + i] ^= ((bsic >> (5 - i)) & 1); + + return 0; +} + +int gsm0503_rach_decode(uint8_t *ra, sbit_t *burst, uint8_t bsic) +{ + ubit_t conv[14]; + int rv; + + osmo_conv_decode(&gsm0503_rach, burst, conv); + + rach_apply_bsic(conv, bsic); + + rv = osmo_crc8gen_check_bits(&gsm0503_rach_crc6, conv, 8, conv + 8); + if (rv) + return -1; + + osmo_ubit2pbit_ext(ra, 0, conv, 0, 8, 1); + + return 0; +} + +int gsm0503_rach_encode(ubit_t *burst, uint8_t *ra, uint8_t bsic) +{ + ubit_t conv[14]; + + osmo_pbit2ubit_ext(conv, 0, ra, 0, 8, 1); + + osmo_crc8gen_set_bits(&gsm0503_rach_crc6, conv, 8, conv + 8); + + rach_apply_bsic(conv, bsic); + + osmo_conv_encode(&gsm0503_rach, conv, burst); + + return 0; +} + +/* + * GSM SCH transcoding + */ +int gsm0503_sch_decode(uint8_t *sb_info, sbit_t *burst) +{ + ubit_t conv[35]; + int rv; + + osmo_conv_decode(&gsm0503_sch, burst, conv); + + rv = osmo_crc16gen_check_bits(&gsm0503_sch_crc10, conv, 25, conv + 25); + if (rv) + return -1; + + osmo_ubit2pbit_ext(sb_info, 0, conv, 0, 25, 1); + + return 0; +} + +int gsm0503_sch_encode(ubit_t *burst, uint8_t *sb_info) +{ + ubit_t conv[35]; + + osmo_pbit2ubit_ext(conv, 0, sb_info, 0, 25, 1); + + osmo_crc16gen_set_bits(&gsm0503_sch_crc10, conv, 25, conv + 25); + + osmo_conv_encode(&gsm0503_sch, conv, burst); + + return 0; +} |