libosmocoding: migrate transcoding routines from OsmoBTS
There are some projects, such as GR-GSM and OsmocomBB, which would
benefit from using one shared implementation of GSM 05.03 code. So,
this commit introduces a new sub-library called libosmocoding, which
(for now) provides GSM, GPRS and EDGE transcoding routines, migrated
from OsmoBTS.
The original GSM 05.03 code from OsmoBTS was relicensed under
GPLv2-or-later with permission of copyright holders (Andreas Eversberg,
Alexander Chemeris and Tom Tsou).
The following data types are currently supported:
- xCCH
- PDTCH (CS 1-4 and MCS 1-9)
- TCH/FR
- TCH/HR
- TCH/AFS
- RCH/AHS
- RACH
- SCH
Change-Id: I0c3256b87686d878e4e716d12393cad5924fdfa1
diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c
new file mode 100644
index 0000000..30ec387
--- /dev/null
+++ b/src/coding/gsm0503_coding.c
@@ -0,0 +1,2681 @@
+/*
+ * (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>
+
+#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/gprs/protocol/gsm_04_60.h>
+#include <osmocom/gprs/gprs_rlc.h>
+
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/gsm0503.h>
+#include <osmocom/codec/codec.h>
+
+#include <osmocom/coding/gsm0503_interleaving.h>
+#include <osmocom/coding/gsm0503_mapping.h>
+#include <osmocom/coding/gsm0503_tables.h>
+#include <osmocom/coding/gsm0503_coding.h>
+#include <osmocom/coding/gsm0503_parity.h>
+
+/*
+ * 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
+
+union gprs_rlc_ul_hdr_egprs {
+ struct gprs_rlc_ul_header_egprs_1 type1;
+ struct gprs_rlc_ul_header_egprs_2 type2;
+ struct gprs_rlc_ul_header_egprs_3 type3;
+};
+
+union gprs_rlc_dl_hdr_egprs {
+ struct gprs_rlc_dl_header_egprs_1 type1;
+ struct gprs_rlc_dl_header_egprs_2 type2;
+ struct gprs_rlc_dl_header_egprs_3 type3;
+};
+
+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];
+};
+
+/*
+ * EGPRS UL coding parameters
+ */
+struct gsm0503_mcs_code gsm0503_mcs_ul_codes[EGPRS_NUM_MCS] = {
+ {
+ .mcs = EGPRS_MCS0,
+ },
+ {
+ .mcs = EGPRS_MCS1,
+ .hdr_len = 31,
+ .hdr_code_len = 117,
+ .hdr_punc_len = 80,
+ .hdr_conv = &gsm0503_mcs1_ul_hdr,
+ .hdr_punc = gsm0503_puncture_mcs1_ul_hdr,
+
+ .data_len = 178,
+ .data_code_len = 588,
+ .data_punc_len = 372,
+ .data_conv = &gsm0503_mcs1,
+ .data_punc = {
+ gsm0503_puncture_mcs1_p1,
+ gsm0503_puncture_mcs1_p2,
+ NULL,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS2,
+ .hdr_len = 31,
+ .hdr_code_len = 117,
+ .hdr_punc_len = 80,
+ .hdr_conv = &gsm0503_mcs1_ul_hdr,
+ .hdr_punc = gsm0503_puncture_mcs1_ul_hdr,
+
+ .data_len = 226,
+ .data_code_len = 732,
+ .data_punc_len = 372,
+ .data_conv = &gsm0503_mcs2,
+ .data_punc = {
+ gsm0503_puncture_mcs2_p1,
+ gsm0503_puncture_mcs2_p2,
+ NULL,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS3,
+ .hdr_len = 31,
+ .hdr_code_len = 117,
+ .hdr_punc_len = 80,
+ .hdr_conv = &gsm0503_mcs1_ul_hdr,
+ .hdr_punc = gsm0503_puncture_mcs1_ul_hdr,
+
+ .data_len = 298,
+ .data_code_len = 948,
+ .data_punc_len = 372,
+ .data_conv = &gsm0503_mcs3,
+ .data_punc = {
+ gsm0503_puncture_mcs3_p1,
+ gsm0503_puncture_mcs3_p2,
+ gsm0503_puncture_mcs3_p3,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS4,
+ .hdr_len = 31,
+ .hdr_code_len = 117,
+ .hdr_punc_len = 80,
+ .hdr_conv = &gsm0503_mcs1_ul_hdr,
+ .hdr_punc = gsm0503_puncture_mcs1_ul_hdr,
+
+ .data_len = 354,
+ .data_code_len = 1116,
+ .data_punc_len = 372,
+ .data_conv = &gsm0503_mcs4,
+ .data_punc = {
+ gsm0503_puncture_mcs4_p1,
+ gsm0503_puncture_mcs4_p2,
+ gsm0503_puncture_mcs4_p3,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS5,
+ .hdr_len = 37,
+ .hdr_code_len = 135,
+ .hdr_punc_len = 136,
+ .hdr_conv = &gsm0503_mcs5_ul_hdr,
+ .hdr_punc = NULL,
+
+ .data_len = 450,
+ .data_code_len = 1404,
+ .data_punc_len = 1248,
+ .data_conv = &gsm0503_mcs5,
+ .data_punc = {
+ gsm0503_puncture_mcs5_p1,
+ gsm0503_puncture_mcs5_p2,
+ NULL,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS6,
+ .hdr_len = 37,
+ .hdr_code_len = 135,
+ .hdr_punc_len = 136,
+ .hdr_conv = &gsm0503_mcs5_ul_hdr,
+ .hdr_punc = NULL,
+
+ .data_len = 594,
+ .data_code_len = 1836,
+ .data_punc_len = 1248,
+ .data_conv = &gsm0503_mcs6,
+ .data_punc = {
+ gsm0503_puncture_mcs6_p1,
+ gsm0503_puncture_mcs6_p2,
+ NULL,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS7,
+ .hdr_len = 46,
+ .hdr_code_len = 162,
+ .hdr_punc_len = 160,
+ .hdr_conv = &gsm0503_mcs7_ul_hdr,
+ .hdr_punc = gsm0503_puncture_mcs7_ul_hdr,
+
+ .data_len = 900,
+ .data_code_len = 1404,
+ .data_punc_len = 612,
+ .data_conv = &gsm0503_mcs7,
+ .data_punc = {
+ gsm0503_puncture_mcs7_p1,
+ gsm0503_puncture_mcs7_p2,
+ gsm0503_puncture_mcs7_p3,
+ }
+ },
+ {
+ .mcs = EGPRS_MCS8,
+ .hdr_len = 46,
+ .hdr_code_len = 162,
+ .hdr_punc_len = 160,
+ .hdr_conv = &gsm0503_mcs7_ul_hdr,
+ .hdr_punc = gsm0503_puncture_mcs7_ul_hdr,
+
+ .data_len = 1092,
+ .data_code_len = 1692,
+ .data_punc_len = 612,
+ .data_conv = &gsm0503_mcs8,
+ .data_punc = {
+ gsm0503_puncture_mcs8_p1,
+ gsm0503_puncture_mcs8_p2,
+ gsm0503_puncture_mcs8_p3,
+ }
+ },
+ {
+ .mcs = EGPRS_MCS9,
+ .hdr_len = 46,
+ .hdr_code_len = 162,
+ .hdr_punc_len = 160,
+ .hdr_conv = &gsm0503_mcs7_ul_hdr,
+ .hdr_punc = gsm0503_puncture_mcs7_ul_hdr,
+
+ .data_len = 1188,
+ .data_code_len = 1836,
+ .data_punc_len = 612,
+ .data_conv = &gsm0503_mcs9,
+ .data_punc = {
+ gsm0503_puncture_mcs9_p1,
+ gsm0503_puncture_mcs9_p2,
+ gsm0503_puncture_mcs9_p3,
+ }
+ },
+};
+
+/*
+ * EGPRS DL coding parameters
+ */
+struct gsm0503_mcs_code gsm0503_mcs_dl_codes[EGPRS_NUM_MCS] = {
+ {
+ .mcs = EGPRS_MCS0,
+ },
+ {
+ .mcs = EGPRS_MCS1,
+ .usf_len = 3,
+ .hdr_len = 28,
+ .hdr_code_len = 108,
+ .hdr_punc_len = 68,
+ .hdr_conv = &gsm0503_mcs1_dl_hdr,
+ .hdr_punc = gsm0503_puncture_mcs1_dl_hdr,
+
+ .data_len = 178,
+ .data_code_len = 588,
+ .data_punc_len = 372,
+ .data_conv = &gsm0503_mcs1,
+ .data_punc = {
+ gsm0503_puncture_mcs1_p1,
+ gsm0503_puncture_mcs1_p2,
+ NULL,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS2,
+ .usf_len = 3,
+ .hdr_len = 28,
+ .hdr_code_len = 108,
+ .hdr_punc_len = 68,
+ .hdr_conv = &gsm0503_mcs1_dl_hdr,
+ .hdr_punc = gsm0503_puncture_mcs1_dl_hdr,
+
+ .data_len = 226,
+ .data_code_len = 732,
+ .data_punc_len = 372,
+ .data_conv = &gsm0503_mcs2,
+ .data_punc = {
+ gsm0503_puncture_mcs2_p1,
+ gsm0503_puncture_mcs2_p2,
+ NULL,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS3,
+ .usf_len = 3,
+ .hdr_len = 28,
+ .hdr_code_len = 108,
+ .hdr_punc_len = 68,
+ .hdr_conv = &gsm0503_mcs1_dl_hdr,
+ .hdr_punc = gsm0503_puncture_mcs1_dl_hdr,
+
+ .data_len = 298,
+ .data_code_len = 948,
+ .data_punc_len = 372,
+ .data_conv = &gsm0503_mcs3,
+ .data_punc = {
+ gsm0503_puncture_mcs3_p1,
+ gsm0503_puncture_mcs3_p2,
+ gsm0503_puncture_mcs3_p3,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS4,
+ .usf_len = 3,
+ .hdr_len = 28,
+ .hdr_code_len = 108,
+ .hdr_punc_len = 68,
+ .hdr_conv = &gsm0503_mcs1_dl_hdr,
+ .hdr_punc = gsm0503_puncture_mcs1_dl_hdr,
+
+ .data_len = 354,
+ .data_code_len = 1116,
+ .data_punc_len = 372,
+ .data_conv = &gsm0503_mcs4,
+ .data_punc = {
+ gsm0503_puncture_mcs4_p1,
+ gsm0503_puncture_mcs4_p2,
+ gsm0503_puncture_mcs4_p3,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS5,
+ .usf_len = 3,
+ .hdr_len = 25,
+ .hdr_code_len = 99,
+ .hdr_punc_len = 100,
+ .hdr_conv = &gsm0503_mcs5_dl_hdr,
+ .hdr_punc = NULL,
+
+ .data_len = 450,
+ .data_code_len = 1404,
+ .data_punc_len = 1248,
+ .data_conv = &gsm0503_mcs5,
+ .data_punc = {
+ gsm0503_puncture_mcs5_p1,
+ gsm0503_puncture_mcs5_p2,
+ NULL,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS6,
+ .usf_len = 3,
+ .hdr_len = 25,
+ .hdr_code_len = 99,
+ .hdr_punc_len = 100,
+ .hdr_conv = &gsm0503_mcs5_dl_hdr,
+ .hdr_punc = NULL,
+
+ .data_len = 594,
+ .data_code_len = 1836,
+ .data_punc_len = 1248,
+ .data_conv = &gsm0503_mcs6,
+ .data_punc = {
+ gsm0503_puncture_mcs6_p1,
+ gsm0503_puncture_mcs6_p2,
+ NULL,
+ },
+ },
+ {
+ .mcs = EGPRS_MCS7,
+ .usf_len = 3,
+ .hdr_len = 37,
+ .hdr_code_len = 135,
+ .hdr_punc_len = 124,
+ .hdr_conv = &gsm0503_mcs7_dl_hdr,
+ .hdr_punc = gsm0503_puncture_mcs7_dl_hdr,
+
+ .data_len = 900,
+ .data_code_len = 1404,
+ .data_punc_len = 612,
+ .data_conv = &gsm0503_mcs7,
+ .data_punc = {
+ gsm0503_puncture_mcs7_p1,
+ gsm0503_puncture_mcs7_p2,
+ gsm0503_puncture_mcs7_p3,
+ }
+ },
+ {
+ .mcs = EGPRS_MCS8,
+ .usf_len = 3,
+ .hdr_len = 37,
+ .hdr_code_len = 135,
+ .hdr_punc_len = 124,
+ .hdr_conv = &gsm0503_mcs7_dl_hdr,
+ .hdr_punc = gsm0503_puncture_mcs7_dl_hdr,
+
+ .data_len = 1092,
+ .data_code_len = 1692,
+ .data_punc_len = 612,
+ .data_conv = &gsm0503_mcs8,
+ .data_punc = {
+ gsm0503_puncture_mcs8_p1,
+ gsm0503_puncture_mcs8_p2,
+ gsm0503_puncture_mcs8_p3,
+ }
+ },
+ {
+ .mcs = EGPRS_MCS9,
+ .usf_len = 3,
+ .hdr_len = 37,
+ .hdr_code_len = 135,
+ .hdr_punc_len = 124,
+ .hdr_conv = &gsm0503_mcs7_dl_hdr,
+ .hdr_punc = gsm0503_puncture_mcs7_dl_hdr,
+
+ .data_len = 1188,
+ .data_code_len = 1836,
+ .data_punc_len = 612,
+ .data_conv = &gsm0503_mcs9,
+ .data_punc = {
+ gsm0503_puncture_mcs9_p1,
+ gsm0503_puncture_mcs9_p2,
+ gsm0503_puncture_mcs9_p3,
+ }
+ },
+};
+
+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;
+}
+
+/*
+ * EGPRS PDTCH UL block decoding
+ */
+
+/*
+ * Type 3 - MCS-1,2,3,4
+ * Unmapping and deinterleaving
+ */
+static int egprs_type3_unmap(const sbit_t *bursts, sbit_t *hc, sbit_t *dc)
+{
+ int i;
+ sbit_t iB[456], q[8];
+
+ for (i = 0; i < 4; i++) {
+ gsm0503_xcch_burst_unmap(&iB[i * 114], &bursts[i * 116],
+ q + i * 2, q + i * 2 + 1);
+ }
+
+ gsm0503_mcs1_ul_deinterleave(hc, dc, iB);
+
+ return 0;
+}
+
+/*
+ * Type 2 - MCS-5,6
+ * Unmapping and deinterleaving
+ */
+static int egprs_type2_unmap(const sbit_t *bursts, sbit_t *hc, sbit_t *dc)
+{
+ int i;
+ sbit_t burst[348];
+ sbit_t hi[EGPRS_HDR_HC_MAX];
+ sbit_t di[EGPRS_DATA_DC_MAX];
+
+ for (i = 0; i < 4; i++) {
+ memcpy(burst, &bursts[i * 348], 348);
+
+ gsm0503_mcs5_burst_swap(burst);
+ gsm0503_mcs5_ul_burst_unmap(di, burst, hi, i);
+ }
+
+ gsm0503_mcs5_ul_deinterleave(hc, dc, hi, di);
+
+ return 0;
+}
+
+/*
+ * Type 1 - MCS-7,8,9
+ * Unmapping and deinterleaving - Note that MCS-7 interleaver is unique
+ */
+static int egprs_type1_unmap(const sbit_t *bursts, sbit_t *hc,
+ sbit_t *c1, sbit_t *c2, int msc)
+{
+ int i;
+ sbit_t burst[348];
+ sbit_t hi[EGPRS_HDR_HC_MAX];
+ sbit_t di[EGPRS_DATA_C1 * 2];
+
+ for (i = 0; i < 4; i++) {
+ memcpy(burst, &bursts[i * 348], 348);
+
+ gsm0503_mcs5_burst_swap(burst);
+ gsm0503_mcs7_ul_burst_unmap(di, burst, hi, i);
+ }
+
+ if (msc == EGPRS_MCS7)
+ gsm0503_mcs7_ul_deinterleave(hc, c1, c2, hi, di);
+ else
+ gsm0503_mcs8_ul_deinterleave(hc, c1, c2, hi, di);
+
+ return 0;
+}
+
+/*
+ * Decode EGPRS UL header section
+ *
+ * 1. Depuncture
+ * 2. Convolutional decoding
+ * 3. CRC check
+ */
+static int _egprs_decode_hdr(const sbit_t *hc, int mcs,
+ union gprs_rlc_ul_hdr_egprs *hdr)
+{
+ sbit_t C[EGPRS_HDR_C_MAX];
+ ubit_t upp[EGPRS_HDR_UPP_MAX];
+ int i, j, rc;
+ struct gsm0503_mcs_code *code;
+
+ code = &gsm0503_mcs_ul_codes[mcs];
+
+ /* Skip depuncturing on MCS-5,6 header */
+ if ((mcs == EGPRS_MCS5) || (mcs == EGPRS_MCS6)) {
+ memcpy(C, hc, code->hdr_code_len);
+ goto hdr_conv_decode;
+ }
+
+ if (!code->hdr_punc) {
+ /* Invalid MCS-X header puncture matrix */
+ return -1;
+ }
+
+ i = code->hdr_code_len - 1;
+ j = code->hdr_punc_len - 1;
+
+ for (; i >= 0; i--) {
+ if (!code->hdr_punc[i])
+ C[i] = hc[j--];
+ else
+ C[i] = 0;
+ }
+
+hdr_conv_decode:
+ osmo_conv_decode_ber(code->hdr_conv, C, upp, NULL, NULL);
+ rc = osmo_crc8gen_check_bits(&gsm0503_mcs_crc8_hdr, upp,
+ code->hdr_len, upp + code->hdr_len);
+ if (rc)
+ return -1;
+
+ osmo_ubit2pbit_ext((pbit_t *) hdr, 0, upp, 0, code->hdr_len, 1);
+
+ return 0;
+}
+
+/*
+ * Blind MCS header decoding based on burst length and CRC validation.
+ * Ignore 'q' value coding identification. This approach provides
+ * the strongest chance of header recovery.
+ */
+static int egprs_decode_hdr(union gprs_rlc_ul_hdr_egprs *hdr,
+ const sbit_t *bursts, uint16_t nbits)
+{
+ int rc;
+ sbit_t hc[EGPRS_HDR_HC_MAX];
+
+ if (nbits == GSM0503_GPRS_BURSTS_NBITS) {
+ /* MCS-1,2,3,4 */
+ egprs_type3_unmap(bursts, hc, NULL);
+ rc = _egprs_decode_hdr(hc, EGPRS_MCS1, hdr);
+ if (!rc)
+ return EGPRS_HDR_TYPE3;
+ } else if (nbits == GSM0503_EGPRS_BURSTS_NBITS) {
+ /* MCS-5,6 */
+ egprs_type2_unmap(bursts, hc, NULL);
+ rc = _egprs_decode_hdr(hc, EGPRS_MCS5, hdr);
+ if (!rc)
+ return EGPRS_HDR_TYPE2;
+
+ /* MCS-7,8,9 */
+ egprs_type1_unmap(bursts, hc, NULL, NULL, EGPRS_MCS7);
+ rc = _egprs_decode_hdr(hc, EGPRS_MCS7, hdr);
+ if (!rc)
+ return EGPRS_HDR_TYPE1;
+ }
+
+ return -1;
+}
+
+/*
+ * Parse EGPRS UL header for coding and puncturing scheme (CPS)
+ *
+ * Type 1 - MCS-7,8,9
+ * Type 2 - MCS-5,6
+ * Type 3 - MCS-1,2,3,4
+ */
+static int egprs_parse_ul_cps(struct egprs_cps *cps,
+ union gprs_rlc_ul_hdr_egprs *hdr, int type)
+{
+ uint8_t bits;
+
+ switch (type) {
+ case EGPRS_HDR_TYPE1:
+ bits = hdr->type1.cps;
+ break;
+ case EGPRS_HDR_TYPE2:
+ bits = (hdr->type2.cps_lo << 2) | hdr->type2.cps_hi;
+ break;
+ case EGPRS_HDR_TYPE3:
+ bits = (hdr->type3.cps_lo << 2) | hdr->type3.cps_hi;
+ break;
+ default:
+ return -1;
+ }
+
+ return egprs_get_cps(cps, type, bits);
+}
+
+/*
+ * Decode EGPRS UL data section
+ *
+ * 1. Depuncture
+ * 2. Convolutional decoding
+ * 3. CRC check
+ * 4. Block combining (MCS-7,8,9 only)
+ */
+static int egprs_decode_data(uint8_t *l2_data, sbit_t *c,
+ int mcs, int p, int blk, int *n_errors, int *n_bits_total)
+{
+ ubit_t u[EGPRS_DATA_U_MAX];
+ sbit_t C[EGPRS_DATA_C_MAX];
+
+ int i, j, rc, data_len;
+ struct gsm0503_mcs_code *code;
+
+ if (blk && mcs < EGPRS_MCS7) {
+ /* Invalid MCS-X block state */
+ return -1;
+ }
+
+ code = &gsm0503_mcs_ul_codes[mcs];
+ if (!code->data_punc[p]) {
+ /* Invalid MCS-X data puncture matrix */
+ return -1;
+ }
+
+ /*
+ * MCS-1,6 - single block processing
+ * MCS-7,9 - dual block processing
+ */
+ if (mcs >= EGPRS_MCS7)
+ data_len = code->data_len / 2;
+ else
+ data_len = code->data_len;
+
+ i = code->data_code_len - 1;
+ j = code->data_punc_len - 1;
+
+ for (; i >= 0; i--) {
+ if (!code->data_punc[p][i])
+ C[i] = c[j--];
+ else
+ C[i] = 0;
+ }
+
+ osmo_conv_decode_ber(code->data_conv, C, u, n_errors, n_bits_total);
+ rc = osmo_crc16gen_check_bits(&gsm0503_mcs_crc12, u,
+ data_len, u + data_len);
+ if (rc)
+ return -1;
+
+ /* Offsets output pointer on the second block of Type 1 MCS */
+ osmo_ubit2pbit_ext(l2_data, code->hdr_len + blk * data_len,
+ u, 0, data_len, 1);
+
+ /* Return the number of bytes required for the bit message */
+ return NUM_BYTES(code->hdr_len + code->data_len);
+}
+
+/*
+ * Decode EGPRS UL message
+ *
+ * 1. Header section decoding
+ * 2. Extract CPS settings
+ * 3. Burst unmapping and deinterleaving
+ * 4. Data section decoding
+ */
+int gsm0503_pdtch_egprs_decode(uint8_t *l2_data, sbit_t *bursts, uint16_t nbits,
+ uint8_t *usf_p, int *n_errors, int *n_bits_total)
+{
+ sbit_t dc[EGPRS_DATA_DC_MAX];
+ sbit_t c1[EGPRS_DATA_C1], c2[EGPRS_DATA_C2];
+ int type, rc;
+ struct egprs_cps cps;
+ union gprs_rlc_ul_hdr_egprs *hdr;
+
+ if ((nbits != GSM0503_GPRS_BURSTS_NBITS) &&
+ (nbits != GSM0503_EGPRS_BURSTS_NBITS)) {
+ /* Invalid EGPRS bit length */
+ return -1;
+ }
+
+ hdr = (union gprs_rlc_ul_hdr_egprs *) l2_data;
+ type = egprs_decode_hdr(hdr, bursts, nbits);
+ if (egprs_parse_ul_cps(&cps, hdr, type) < 0)
+ return -1;
+
+ switch (cps.mcs) {
+ case EGPRS_MCS1:
+ case EGPRS_MCS2:
+ case EGPRS_MCS3:
+ case EGPRS_MCS4:
+ egprs_type3_unmap(bursts, NULL, dc);
+ break;
+ case EGPRS_MCS5:
+ case EGPRS_MCS6:
+ egprs_type2_unmap(bursts, NULL, dc);
+ break;
+ case EGPRS_MCS7:
+ case EGPRS_MCS8:
+ case EGPRS_MCS9:
+ egprs_type1_unmap(bursts, NULL, c1, c2, cps.mcs);
+ break;
+ default:
+ /* Invalid MCS-X */
+ return -1;
+ }
+
+ /* Decode MCS-X block, where X = cps.mcs */
+ if (cps.mcs < EGPRS_MCS7) {
+ rc = egprs_decode_data(l2_data, dc, cps.mcs, cps.p[0],
+ 0, n_errors, n_bits_total);
+ if (rc < 0)
+ return -1;
+ } else {
+ /* MCS-7,8,9 block 1 */
+ rc = egprs_decode_data(l2_data, c1, cps.mcs, cps.p[0],
+ 0, n_errors, n_bits_total);
+ if (rc < 0)
+ return -1;
+
+ /* MCS-7,8,9 block 2 */
+ rc = egprs_decode_data(l2_data, c2, cps.mcs, cps.p[1],
+ 1, n_errors, n_bits_total);
+ if (rc < 0)
+ return -1;
+ }
+
+ return rc;
+}
+
+/*
+ * 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_np, 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_np, 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;
+}
+
+/*
+ * EGPRS PDTCH UL block encoding
+ */
+static int egprs_type3_map(ubit_t *bursts, ubit_t *hc, ubit_t *dc, int usf)
+{
+ int i;
+ ubit_t iB[456];
+ const ubit_t *hl_hn = gsm0503_pdtch_hl_hn_ubit[3];
+
+ gsm0503_mcs1_dl_interleave(gsm0503_usf2six[usf], hc, dc, 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 0;
+}
+
+static int egprs_type2_map(ubit_t *bursts, ubit_t *hc, ubit_t *dc, int usf)
+{
+ int i;
+ const ubit_t *up;
+ ubit_t hi[EGPRS_HDR_HC_MAX];
+ ubit_t di[EGPRS_DATA_DC_MAX];
+
+ gsm0503_mcs5_dl_interleave(hc, dc, hi, di);
+ up = gsm0503_mcs5_usf_precode_table[usf];
+
+ for (i = 0; i < 4; i++) {
+ gsm0503_mcs5_dl_burst_map(di, &bursts[i * 348], hi, up, i);
+ gsm0503_mcs5_burst_swap((sbit_t *) &bursts[i * 348]);
+ }
+
+ return 0;
+}
+
+static int egprs_type1_map(ubit_t *bursts, ubit_t *hc,
+ ubit_t *c1, ubit_t *c2, int usf, int mcs)
+{
+ int i;
+ const ubit_t *up;
+ ubit_t hi[EGPRS_HDR_HC_MAX];
+ ubit_t di[EGPRS_DATA_C1 * 2];
+
+ if (mcs == EGPRS_MCS7)
+ gsm0503_mcs7_dl_interleave(hc, c1, c2, hi, di);
+ else
+ gsm0503_mcs8_dl_interleave(hc, c1, c2, hi, di);
+
+ up = gsm0503_mcs5_usf_precode_table[usf];
+
+ for (i = 0; i < 4; i++) {
+ gsm0503_mcs7_dl_burst_map(di, &bursts[i * 348], hi, up, i);
+ gsm0503_mcs5_burst_swap((sbit_t *) &bursts[i * 348]);
+ }
+
+ return 0;
+}
+
+static int egprs_encode_hdr(ubit_t *hc, uint8_t *l2_data, int mcs)
+{
+ int i, j;
+ ubit_t upp[EGPRS_HDR_UPP_MAX], C[EGPRS_HDR_C_MAX];
+ struct gsm0503_mcs_code *code;
+
+ code = &gsm0503_mcs_dl_codes[mcs];
+
+ osmo_pbit2ubit_ext(upp, 0, l2_data, code->usf_len, code->hdr_len, 1);
+ osmo_crc8gen_set_bits(&gsm0503_mcs_crc8_hdr, upp,
+ code->hdr_len, upp + code->hdr_len);
+
+ osmo_conv_encode(code->hdr_conv, upp, C);
+
+ /* MCS-5,6 header direct puncture instead of table */
+ if ((mcs == EGPRS_MCS5) || (mcs == EGPRS_MCS6)) {
+ memcpy(hc, C, code->hdr_code_len);
+ hc[99] = hc[98];
+ return 0;
+ }
+
+ if (!code->hdr_punc) {
+ /* Invalid MCS-X header puncture matrix */
+ return -1;
+ }
+
+ for (i = 0, j = 0; i < code->hdr_code_len; i++) {
+ if (!code->hdr_punc[i])
+ hc[j++] = C[i];
+ }
+
+ return 0;
+}
+
+static int egprs_encode_data(ubit_t *c, uint8_t *l2_data,
+ int mcs, int p, int blk)
+{
+ int i, j, data_len;
+ ubit_t u[EGPRS_DATA_U_MAX], C[EGPRS_DATA_C_MAX];
+ struct gsm0503_mcs_code *code;
+
+ code = &gsm0503_mcs_dl_codes[mcs];
+
+ /*
+ * Dual block - MCS-7,8,9
+ * Single block - MCS-1,2,3,4,5,6
+ */
+ if (mcs >= EGPRS_MCS7)
+ data_len = code->data_len / 2;
+ else
+ data_len = code->data_len;
+
+ osmo_pbit2ubit_ext(u, 0, l2_data,
+ code->usf_len + code->hdr_len + blk * data_len, data_len, 1);
+
+ osmo_crc16gen_set_bits(&gsm0503_mcs_crc12, u, data_len, u + data_len);
+
+ osmo_conv_encode(code->data_conv, u, C);
+
+ if (!code->data_punc[p]) {
+ /* Invalid MCS-X data puncture matrix */
+ return -1;
+ }
+
+ for (i = 0, j = 0; i < code->data_code_len; i++) {
+ if (!code->data_punc[p][i])
+ c[j++] = C[i];
+ }
+
+ return 0;
+}
+
+/*
+ * Parse EGPRS DL header for coding and puncturing scheme (CPS)
+ *
+ * Type 1 - MCS-7,8,9
+ * Type 2 - MCS-5,6
+ * Type 3 - MCS-1,2,3,4
+ */
+static int egprs_parse_dl_cps(struct egprs_cps *cps,
+ union gprs_rlc_dl_hdr_egprs *hdr, int type)
+{
+ uint8_t bits;
+
+ switch (type) {
+ case EGPRS_HDR_TYPE1:
+ bits = hdr->type1.cps;
+ break;
+ case EGPRS_HDR_TYPE2:
+ bits = hdr->type2.cps;
+ break;
+ case EGPRS_HDR_TYPE3:
+ bits = hdr->type3.cps;
+ break;
+ default:
+ return -1;
+ }
+
+ return egprs_get_cps(cps, type, bits);
+}
+
+/*
+ * EGPRS DL message encoding
+ */
+int gsm0503_pdtch_egprs_encode(ubit_t *bursts,
+ uint8_t *l2_data, uint8_t l2_len)
+{
+ ubit_t hc[EGPRS_DATA_C_MAX], dc[EGPRS_DATA_DC_MAX];
+ ubit_t c1[EGPRS_DATA_C1], c2[EGPRS_DATA_C2];
+ uint8_t mcs;
+ struct egprs_cps cps;
+ union gprs_rlc_dl_hdr_egprs *hdr;
+
+ switch (l2_len) {
+ case 27:
+ mcs = EGPRS_MCS1;
+ break;
+ case 33:
+ mcs = EGPRS_MCS2;
+ break;
+ case 42:
+ mcs = EGPRS_MCS3;
+ break;
+ case 49:
+ mcs = EGPRS_MCS4;
+ break;
+ case 60:
+ mcs = EGPRS_MCS5;
+ break;
+ case 78:
+ mcs = EGPRS_MCS6;
+ break;
+ case 118:
+ mcs = EGPRS_MCS7;
+ break;
+ case 142:
+ mcs = EGPRS_MCS8;
+ break;
+ case 154:
+ mcs = EGPRS_MCS9;
+ break;
+ default:
+ return -1;
+ }
+
+ /* Read header for USF and puncturing matrix selection. */
+ hdr = (union gprs_rlc_dl_hdr_egprs *) l2_data;
+
+ switch (mcs) {
+ case EGPRS_MCS1:
+ case EGPRS_MCS2:
+ case EGPRS_MCS3:
+ case EGPRS_MCS4:
+ /* Check for valid CPS and matching MCS to message size */
+ if ((egprs_parse_dl_cps(&cps, hdr, EGPRS_HDR_TYPE3) < 0) ||
+ (cps.mcs != mcs))
+ goto bad_header;
+
+ egprs_encode_hdr(hc, l2_data, mcs);
+ egprs_encode_data(dc, l2_data, mcs, cps.p[0], 0);
+ egprs_type3_map(bursts, hc, dc, hdr->type3.usf);
+ break;
+ case EGPRS_MCS5:
+ case EGPRS_MCS6:
+ if ((egprs_parse_dl_cps(&cps, hdr, EGPRS_HDR_TYPE2) < 0) ||
+ (cps.mcs != mcs))
+ goto bad_header;
+
+ egprs_encode_hdr(hc, l2_data, mcs);
+ egprs_encode_data(dc, l2_data, mcs, cps.p[0], 0);
+ egprs_type2_map(bursts, hc, dc, hdr->type2.usf);
+ break;
+ case EGPRS_MCS7:
+ case EGPRS_MCS8:
+ case EGPRS_MCS9:
+ if ((egprs_parse_dl_cps(&cps, hdr, EGPRS_HDR_TYPE1) < 0) ||
+ (cps.mcs != mcs))
+ goto bad_header;
+
+ egprs_encode_hdr(hc, l2_data, mcs);
+ egprs_encode_data(c1, l2_data, mcs, cps.p[0], 0);
+ egprs_encode_data(c2, l2_data, mcs, cps.p[1], 1);
+ egprs_type1_map(bursts, hc, c1, c2, hdr->type1.usf, mcs);
+ break;
+ }
+
+ return mcs >= EGPRS_MCS5 ?
+ GSM0503_EGPRS_BURSTS_NBITS : GSM0503_GPRS_BURSTS_NBITS;
+
+bad_header:
+ /* Invalid EGPRS MCS-X header */
+ 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_np, 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_np, 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;
+}