trau_frame: New API
The old TRAU frame code in src/trau_frame.c (which is for some strange
reason part of libosmo-abis, and not libosmo-trau!) was introduced more
than a decade ago for the needs of bs11_abis AKA OpenBSC aka OsmoNITB.
It is too constrained to implement TRAU frame parsing in a generic way,
including:
* no way to add support for 8k sub-slots
* no way to handle CRC bits or UFI (i.e. no AMR)
* no real API design, it was just ripped out from OsmoNITB and moved into
a library (even the wrong one)
For those reasons, let's introduce a new API for TRAU frame
encoding/decoding - one that supports all the relevant use cases.
Change-Id: I5cf42e6c445d9224be18503cebc7584b3beba08c
diff --git a/include/osmocom/trau/trau_frame.h b/include/osmocom/trau/trau_frame.h
new file mode 100644
index 0000000..6784d1f
--- /dev/null
+++ b/include/osmocom/trau/trau_frame.h
@@ -0,0 +1,146 @@
+#pragma once
+/* TRAU frame handling according to GSM TS 48.060 / 48.061 */
+
+/* (C) 2020 by Harald Welte <laforge@gnumonks.org>
+ * 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 Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <osmocom/core/bits.h>
+#include <osmocom/core/utils.h>
+
+/*! \defgroup trau_frame TRAU frame handling
+ * @{
+ *
+ * \file trau_frame.h
+ */
+
+/*! \brief Maximum number of C-bits in a TRAU frame:
+ * 21 for FR/EFR, 25 for AMR, 15 for OM, 15 for data, 13 for E-data, 21 idle */
+#define MAX_C_BITS 25
+/*! \brief Maximum number of D-bits in a TRAU frame:
+ * 260 for FR/EFR, 256 for AMR, 264 for OM, 288 for E-data */
+#define MAX_D_BITS 288
+/*! \brief Maximum number of T-bits in a TRAU frame for all speech frames */
+#define MAX_T_BITS 4
+/*! \brief Maximum number of S-bits in a TRAU frame for OM */
+#define MAX_S_BITS 6
+/*! \brief Maximum number of M-bits in a TRAU frame for E-data */
+#define MAX_M_BITS 2
+/*! \brief Maximum number of XC-bits in a TRAU frame for 8k */
+#define MAX_XC_BITS 6
+
+/*! 16k sub-slot types: Bits C1..C5 */
+#define TRAU_FT_FR_UP 0x02 /* 0 0 0 1 0 - 3.5.1.1.1 */
+#define TRAU_FT_HR_UP 0x03 /* 0 0 0 1 1 - TS 08.61 5.1.4.1.1 */
+#define TRAU_FT_FR_DOWN 0x1c /* 1 1 1 0 0 - 3.5.1.1.1 */
+#define TRAU_FT_HR_DOWN 0x1d /* 1 1 1 0 1 - TS 08.61 5.1.4.1.1 */
+#define TRAU_FT_EFR 0x1a /* 1 1 0 1 0 - 3.5.1.1.1 */
+#define TRAU_FT_AMR 0x06 /* 0 0 1 1 0 - 3.5.1.2 */
+#define TRAU_FT_OM_UP 0x05 /* 0 0 1 0 1 - 3.5.2 */
+#define TRAU_FT_OM_DOWN 0x1b /* 1 1 0 1 1 - 3.5.2 */
+#define TRAU_FT_DATA_UP 0x08 /* 0 1 0 0 0 - 3.5.3 */
+#define TRAU_FT_DATA_UP_HR 0x09 /* 0 1 0 0 1 - TS 08.61 5.1.4.2 */
+#define TRAU_FT_DATA_DOWN 0x16 /* 1 0 1 1 0 - 3.5.3 */
+#define TRAU_FT_DATA_DOWN_HR 0x17 /* 1 0 1 1 1 - TS 08.61 5.1.4.2 */
+#define TRAU_FT_D145_SYNC 0x14 /* 1 0 1 0 0 - 3.5.3 */
+#define TRAU_FT_EDATA 0x1f /* 1 1 1 1 1 - 3.5.4 */
+#define TRAU_FT_IDLE_UP 0x10 /* 1 0 0 0 0 - 3.5.5 */
+#define TRAU_FT_IDLE_DOWN 0x0e /* 0 1 1 1 0 - 3.5.5 */
+
+/* 8k sub-slot types: Bits C1..C5*/
+#define TRAU8_FT_SPEECH_UP 0x02 /* 0 0 0 1 P - TS 08.61 5.2.4.1.1 */
+#define TRAU8_FT_DATA_UP 0x06 /* 0 0 1 1 P - TS 08.61 5.2.4.1.1 */
+#define TRAU8_FT_OM_UP 0x0a /* 0 1 0 1 P - TS 08.61 5.2.4.1.1 */
+#define TRAU8_FT_SPEECH_DOWN 0x00 /* 0 0 0 U P - TS 08.61 5.2.4.1.2 */
+#define TRAU8_FT_DATA_DOWN 0x04 /* 0 0 1 U P - TS 08.61 5.2.4.1.2 */
+#define TRAU8_FT_OM_DOWN 0x08 /* 0 1 0 U P - TS 08.61 5.2.4.1.2 */
+
+/*********************************************************************************
+ * New API
+ *********************************************************************************/
+
+enum osmo_trau_frame_type {
+ OSMO_TRAU_FT_NONE,
+ OSMO_TRAU16_FT_FR = 1,
+ OSMO_TRAU16_FT_HR,
+ OSMO_TRAU16_FT_EFR,
+ OSMO_TRAU16_FT_AMR,
+ OSMO_TRAU16_FT_OAM,
+ OSMO_TRAU16_FT_DATA,
+ OSMO_TRAU16_FT_EDATA,
+ OSMO_TRAU16_FT_D145_SYNC,
+ OSMO_TRAU16_FT_DATA_HR,
+ OSMO_TRAU16_FT_IDLE,
+
+ OSMO_TRAU8_SPEECH,
+ OSMO_TRAU8_DATA,
+ OSMO_TRAU8_OAM,
+ OSMO_TRAU8_AMR_LOW,
+ OSMO_TRAU8_AMR_6k7,
+ OSMO_TRAU8_AMR_7k4,
+};
+
+extern const struct value_string osmo_trau_frame_type_names[];
+static inline const char *osmo_trau_frame_type_name(enum osmo_trau_frame_type ft) {
+ return get_value_string(osmo_trau_frame_type_names, ft);
+}
+
+enum osmo_trau_frame_direction {
+ OSMO_TRAU_DIR_UL = 0,
+ OSMO_TRAU_DIR_DL = 1,
+};
+
+struct osmo_trau_frame {
+ enum osmo_trau_frame_type type;
+ enum osmo_trau_frame_direction dir;
+
+ ubit_t c_bits[MAX_C_BITS];
+ ubit_t d_bits[MAX_D_BITS];
+ ubit_t t_bits[MAX_T_BITS];
+ ubit_t s_bits[MAX_S_BITS];
+ ubit_t m_bits[MAX_M_BITS];
+ ubit_t ufi; /*!< Unreliable Frame Indication (HR) */
+ ubit_t crc_bits[3]; /*!< CRC0..CRC2 (HR) */
+ ubit_t xc_bits[MAX_XC_BITS]; /*!< XC1..XC6 (8k) */
+};
+
+/*! decode an 8k TRAU frame
+ * \param[out] fr caller-allocated output data structure
+ * \param[in] bits unpacked input bits
+ * \param[in] dir direction
+ * \return 0 on success; negative in case of error */
+int osmo_trau_frame_decode_8k(struct osmo_trau_frame *fr, const ubit_t *bits,
+ enum osmo_trau_frame_direction dir);
+
+/*! decode an 16k TRAU frame
+ * \param[out] fr caller-allocated output data structure
+ * \param[in] bits unpacked input bits
+ * \param[in] dir direction
+ * \return 0 on success; negative in case of error */
+int osmo_trau_frame_decode_16k(struct osmo_trau_frame *fr, const ubit_t *bits,
+ enum osmo_trau_frame_direction dir);
+
+/*! encode a TRAU frame
+ * \param[out] bits caller-allocated memory for unpacked output bits
+ * \param[out] fr input data structure describing TRAU frame
+ * \return number of bits encoded */
+int osmo_trau_frame_encode(ubit_t *bits, size_t n_bits, const struct osmo_trau_frame *fr);
+
+
+/* }@ */