falconia has uploaded this change for review.
libosmotrau: add CSD RA2 functions
Rate adaption function RA2 for GSM CSD calls is defined in 3GPP TS
48.020 chapter 13. While it is nothing but one special case of I.460
submultiplexing and we do have i460_mux infrastructure in Osmocom,
that fully-general I.460 infra is too heaviweight for CSD encoding
and decoding functions that need simple, single-input and single-output
RA2 packing and unpacking functions.
Right now ad hoc RA2 functions are used in the trau_rtp_conv module
and in OsmoBTS csd_v110; same functions will also be needed for the
upcoming RAA' unit test addition. Add proper RA2 packing and unpacking
functions that can be used in all of these places.
Change-Id: I7b98b958651b3fc1a814d119d1b8644c91f98676
---
M include/Makefile.am
A include/osmocom/trau/csd_ra2.h
M src/Makefile.am
A src/trau/csd_ra2.c
4 files changed, 140 insertions(+), 1 deletion(-)
git pull ssh://gerrit.osmocom.org:29418/libosmo-abis refs/changes/90/38290/1
diff --git a/include/Makefile.am b/include/Makefile.am
index 88d66dc..2832541 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -4,6 +4,7 @@
osmocom/abis/ipa_proxy.h osmocom/abis/ipaccess.h osmocom/abis/abis.h \
osmocom/abis/subchan_demux.h osmocom/abis/e1_input.h \
osmocom/abis/lapd.h osmocom/abis/lapd_pcap.h osmocom/abis/unixsocket_proto.h \
+ osmocom/trau/csd_ra2.h \
osmocom/trau/trau_frame.h \
osmocom/trau/trau_sync.h \
osmocom/trau/trau_pcu_ericsson.h \
diff --git a/include/osmocom/trau/csd_ra2.h b/include/osmocom/trau/csd_ra2.h
new file mode 100644
index 0000000..a629391
--- /dev/null
+++ b/include/osmocom/trau/csd_ra2.h
@@ -0,0 +1,67 @@
+/*
+ * Rate adaption function RA2 for GSM CSD calls is defined in 3GPP TS
+ * 48.020 chapter 13. While it is nothing but one special case of I.460
+ * submultiplexing and we do have i460_mux infrastructure in Osmocom,
+ * that fully-general I.460 infra is too heaviweight for CSD encoding
+ * and decoding functions that need simple, single-input and single-output
+ * RA2 packing and unpacking functions.
+ *
+ * This header file defines the API to CSD-oriented RA2 packing and unpacking
+ * functions that support intermediate rates of 8 and 16 kbit/s: the two IRs
+ * that occur in "plain" single-slot CSD without EDGE.
+ *
+ * Author: Mychaela N. Falconia <falcon@freecalypso.org>, 2024 - however,
+ * Mother Mychaela's contributions are NOT subject to copyright.
+ * No rights reserved, all rights relinquished.
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <osmocom/core/bits.h>
+
+/*! pack bits into octets per RA2 with 8 kbit/s IR
+ * param[out] out_bytes caller-provided buffer of size nbytes
+ * param[in] in_bits source bits to be packed, size nbytes
+ * param[in] nbytes number of output bytes to pack, equals number of
+ * source bits with 8 kbit/s IR
+ */
+void osmo_csd_ra2_8k_pack(uint8_t *out_bytes, const ubit_t *in_bits,
+ unsigned nbytes);
+
+/*! unpack bits from octets per RA2 with 8 kbit/s IR
+ * param[out] out_bits caller-provided buffer of size nbytes
+ * param[in] in_bytes received 64 kbit/s octets to unpack, size nbytes
+ * param[in] nbytes number of received octets to unpack, equals number
+ * of output bits with 8 kbit/s IR
+ */
+void osmo_csd_ra2_8k_unpack(ubit_t *out_bits, const uint8_t *in_bytes,
+ unsigned nbytes);
+
+/*! pack bits into octets per RA2 with 16 kbit/s IR
+ * param[out] out_bytes caller-provided buffer of size nbytes
+ * param[in] in_bits source bits to be packed, size nbytes*2
+ * param[in] nbytes number of output bytes to pack; the number of
+ * source bits is double this number
+ */
+void osmo_csd_ra2_16k_pack(uint8_t *out_bytes, const ubit_t *in_bits,
+ unsigned nbytes);
+
+/*! unpack bits from octets per RA2 with 16 kbit/s IR
+ * param[out] out_bits caller-provided buffer of size nbytes*2
+ * param[in] in_bytes received 64 kbit/s octets to unpack, size nbytes
+ * param[in] nbytes number of received octets to unpack; the number
+ * of output bits is double this number
+ */
+void osmo_csd_ra2_16k_unpack(ubit_t *out_bits, const uint8_t *in_bytes,
+ unsigned nbytes);
diff --git a/src/Makefile.am b/src/Makefile.am
index 7c59ec3..1df7f4c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -41,7 +41,8 @@
-no-undefined \
$(NULL)
libosmotrau_la_LIBADD = $(COMMONLIBS) $(LIBOSMOCODEC_LIBS) $(ORTP_LIBS)
-libosmotrau_la_SOURCES = trau/trau_frame.c \
+libosmotrau_la_SOURCES = trau/csd_ra2.c \
+ trau/trau_frame.c \
trau/trau_pcu_ericsson.c \
trau/trau_sync.c \
trau/trau_rtp_conv.c
diff --git a/src/trau/csd_ra2.c b/src/trau/csd_ra2.c
new file mode 100644
index 0000000..c44aa7c
--- /dev/null
+++ b/src/trau/csd_ra2.c
@@ -0,0 +1,70 @@
+/*
+ * This C module contains the implementation of CSD RA2 functions
+ * defined in <osmocom/trau/csd_ra2.h>.
+ *
+ * Author: Mychaela N. Falconia <falcon@freecalypso.org>, 2024 - however,
+ * Mother Mychaela's contributions are NOT subject to copyright.
+ * No rights reserved, all rights relinquished.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <stdint.h>
+
+#include <osmocom/core/bits.h>
+#include <osmocom/trau/csd_ra2.h>
+
+void osmo_csd_ra2_8k_pack(uint8_t *out_bytes, const ubit_t *in_bits,
+ unsigned nbytes)
+{
+ unsigned i;
+
+ /* RA2: 1 bit per output byte */
+ for (i = 0; i < nbytes; i++)
+ out_bytes[i] = 0x7F | (in_bits[i] << 7);
+}
+
+void osmo_csd_ra2_8k_unpack(ubit_t *out_bits, const uint8_t *in_bytes,
+ unsigned nbytes)
+{
+ unsigned i;
+
+ for (i = 0; i < nbytes; i++)
+ out_bits[i] = (in_bytes[i] >> 7) & 1;
+}
+
+void osmo_csd_ra2_16k_pack(uint8_t *out_bytes, const ubit_t *in_bits,
+ unsigned nbytes)
+{
+ unsigned i, o;
+ uint8_t b;
+
+ /* RA2: 2 bits per output byte */
+ i = 0;
+ for (o = 0; o < nbytes; o++) {
+ b = 0x3F;
+ b |= (in_bits[i++] << 7);
+ b |= (in_bits[i++] << 6);
+ out_bytes[o] = b;
+ }
+}
+
+void osmo_csd_ra2_16k_unpack(ubit_t *out_bits, const uint8_t *in_bytes,
+ unsigned nbytes)
+{
+ unsigned i, o;
+
+ o = 0;
+ for (i = 0; i < nbytes; i++) {
+ out_bits[o++] = (in_bytes[i] >> 7) & 1;
+ out_bits[o++] = (in_bytes[i] >> 6) & 1;
+ }
+}
To view, visit change 38290. To unsubscribe, or for help writing mail filters, visit settings.