This is merely a historical archive of years 2008-2021, before the migration to mailman3.
A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/OpenBSC@lists.osmocom.org/.
Andreas Eversberg jolly at eversberg.euDecoding and encoding of FR and EFR TRAU frames are put into seperate
functions. CRC check is done to detect bad EFR TRAU frames.
EFR support was tested with Nokia InSite BTS.
---
openbsc/include/openbsc/mncc.h | 1 +
openbsc/src/libmsc/gsm_04_08.c | 1 +
openbsc/src/libtrau/trau_mux.c | 307 ++++++++++++++++++++++++++++++++--------
3 files changed, 251 insertions(+), 58 deletions(-)
diff --git a/openbsc/include/openbsc/mncc.h b/openbsc/include/openbsc/mncc.h
index 4a99bb1..ffc247b 100644
--- a/openbsc/include/openbsc/mncc.h
+++ b/openbsc/include/openbsc/mncc.h
@@ -95,6 +95,7 @@ struct gsm_call {
#define GSM_TCHF_FRAME 0x0300
#define GSM_TCHF_FRAME_EFR 0x0301
+#define GSM_TCHF_BAD_FRAME 0x03ff
#define MNCC_SOCKET_HELLO 0x0400
diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c
index 7a92e4d..2df27a0 100644
--- a/openbsc/src/libmsc/gsm_04_08.c
+++ b/openbsc/src/libmsc/gsm_04_08.c
@@ -2910,6 +2910,7 @@ int mncc_tx_to_cc(struct gsm_network *net, int msg_type, void *arg)
case MNCC_FRAME_RECV:
return tch_recv_mncc(net, data->callref, 1);
case GSM_TCHF_FRAME:
+ case GSM_TCHF_FRAME_EFR:
/* Find callref */
trans = trans_find_by_callref(net, data->callref);
if (!trans) {
diff --git a/openbsc/src/libtrau/trau_mux.c b/openbsc/src/libtrau/trau_mux.c
index d25e78f..f35fa67 100644
--- a/openbsc/src/libtrau/trau_mux.c
+++ b/openbsc/src/libtrau/trau_mux.c
@@ -31,6 +31,7 @@
#include <osmocom/core/talloc.h>
#include <openbsc/trau_upqueue.h>
#include <openbsc/transaction.h>
+#include <osmocom/core/crcgen.h>
/* this corresponds to the bit-lengths of the individual codec
* parameters as indicated in Table 1.1 of TS 06.10 */
@@ -47,6 +48,53 @@ static const uint8_t gsm_fr_map[] = {
3, 3, 3, 3
};
+
+/*
+ * EFR TRAU parity
+ *
+ * g(x) = x^3 + x^1 + 1
+ */
+const struct osmo_crc8gen_code gsm0860_efr_crc3 = {
+ .bits = 3,
+ .poly = 0x3,
+ .init = 0x0,
+ .remainder = 0x7,
+};
+
+/* EFR parity bits */
+static inline void efr_parity_bits_1(ubit_t *check_bits, const ubit_t *d_bits)
+{
+ memcpy(check_bits + 0 , d_bits + 0, 22);
+ memcpy(check_bits + 22 , d_bits + 24, 3);
+ check_bits[25] = d_bits[28];
+}
+
+static inline void efr_parity_bits_2(ubit_t *check_bits, const ubit_t *d_bits)
+{
+ memcpy(check_bits + 0 , d_bits + 42, 10);
+ memcpy(check_bits + 10 , d_bits + 90, 2);
+}
+
+static inline void efr_parity_bits_3(ubit_t *check_bits, const ubit_t *d_bits)
+{
+ memcpy(check_bits + 0 , d_bits + 98, 5);
+ check_bits[5] = d_bits[104];
+ memcpy(check_bits + 6 , d_bits + 143, 2);
+}
+
+static inline void efr_parity_bits_4(ubit_t *check_bits, const ubit_t *d_bits)
+{
+ memcpy(check_bits + 0 , d_bits + 151, 10);
+ memcpy(check_bits + 10 , d_bits + 199, 2);
+}
+
+static inline void efr_parity_bits_5(ubit_t *check_bits, const ubit_t *d_bits)
+{
+ memcpy(check_bits + 0 , d_bits + 207, 5);
+ check_bits[5] = d_bits[213];
+ memcpy(check_bits + 6 , d_bits + 252, 2);
+}
+
struct map_entry {
struct llist_head list;
struct gsm_e1_subslot src, dst;
@@ -159,7 +207,117 @@ lookup_trau_upqueue(const struct gsm_e1_subslot *src)
return NULL;
}
-static const uint8_t c_bits_check[] = { 0, 0, 0, 1, 0 };
+static const uint8_t c_bits_check_fr[] = { 0, 0, 0, 1, 0 };
+static const uint8_t c_bits_check_efr[] = { 1, 1, 0, 1, 0 };
+
+static struct msgb *trau_decode_fr(struct upqueue_entry *ue,
+ const struct decoded_trau_frame *tf)
+{
+ struct msgb *msg;
+ struct gsm_data_frame *frame;
+ unsigned char *data;
+ int i, j, k, l, o;
+
+ msg = msgb_alloc(sizeof(struct gsm_data_frame) + 33,
+ "GSM-DATA");
+ if (!msg)
+ return NULL;
+
+ frame = (struct gsm_data_frame *)msg->data;
+ memset(frame, 0, sizeof(struct gsm_data_frame));
+ data = frame->data;
+ data[0] = 0xd << 4;
+ /* reassemble d-bits */
+ i = 0; /* counts bits */
+ j = 4; /* counts output bits */
+ k = gsm_fr_map[0]-1; /* current number bit in element */
+ l = 0; /* counts element bits */
+ o = 0; /* offset input bits */
+ while (i < 260) {
+ data[j/8] |= (tf->d_bits[k+o] << (7-(j%8)));
+ if (--k < 0) {
+ o += gsm_fr_map[l];
+ k = gsm_fr_map[++l]-1;
+ }
+ i++;
+ j++;
+ }
+ frame->msg_type = GSM_TCHF_FRAME;
+ frame->callref = ue->callref;
+ msgb_put(msg, sizeof(struct gsm_data_frame) + 33);
+
+ return msg;
+}
+
+static struct msgb *trau_decode_efr(struct upqueue_entry *ue,
+ const struct decoded_trau_frame *tf)
+{
+ struct msgb *msg;
+ struct gsm_data_frame *frame;
+ unsigned char *data;
+ int i, j, rc;
+ ubit_t check_bits[26];
+
+ msg = msgb_alloc(sizeof(struct gsm_data_frame) + 31,
+ "GSM-DATA");
+ if (!msg)
+ return NULL;
+
+ frame = (struct gsm_data_frame *)msg->data;
+ memset(frame, 0, sizeof(struct gsm_data_frame));
+ frame->msg_type = GSM_TCHF_FRAME_EFR;
+ frame->callref = ue->callref;
+ msgb_put(msg, sizeof(struct gsm_data_frame) + 31);
+
+ if (tf->c_bits[11]) /* BFI */
+ goto bad_frame;
+
+ data = frame->data;
+ data[0] = 0xc << 4;
+ /* reassemble d-bits */
+ for (i = 1, j = 4; i < 39; i++, j++)
+ data[j/8] |= (tf->d_bits[i] << (7-(j%8)));
+ efr_parity_bits_1(check_bits, tf->d_bits);
+ rc = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 26,
+ tf->d_bits + 39);
+ if (rc)
+ goto bad_frame;
+ for (i = 42, j = 42; i < 95; i++, j++)
+ data[j/8] |= (tf->d_bits[i] << (7-(j%8)));
+ efr_parity_bits_2(check_bits, tf->d_bits);
+ rc = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 12,
+ tf->d_bits + 95);
+ if (rc)
+ goto bad_frame;
+ for (i = 98, j = 95; i < 148; i++, j++)
+ data[j/8] |= (tf->d_bits[i] << (7-(j%8)));
+ efr_parity_bits_3(check_bits, tf->d_bits);
+ rc = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 8,
+ tf->d_bits + 148);
+ if (rc)
+ goto bad_frame;
+ for (i = 151, j = 145; i < 204; i++, j++)
+ data[j/8] |= (tf->d_bits[i] << (7-(j%8)));
+ efr_parity_bits_4(check_bits, tf->d_bits);
+ rc = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 12,
+ tf->d_bits + 204);
+ if (rc)
+ goto bad_frame;
+ for (i = 207, j = 198; i < 257; i++, j++)
+ data[j/8] |= (tf->d_bits[i] << (7-(j%8)));
+ efr_parity_bits_5(check_bits, tf->d_bits);
+ rc = osmo_crc8gen_check_bits(&gsm0860_efr_crc3, check_bits, 8,
+ tf->d_bits + 257);
+ if (rc)
+ goto bad_frame;
+
+ return msg;
+
+bad_frame:
+ frame->msg_type = GSM_TCHF_BAD_FRAME;
+
+ return msg;
+}
/* we get called by subchan_demux */
int trau_mux_input(struct gsm_e1_subslot *src_e1_ss,
@@ -178,45 +336,25 @@ int trau_mux_input(struct gsm_e1_subslot *src_e1_ss,
return rc;
if (!dst_e1_ss) {
- struct msgb *msg;
- struct gsm_data_frame *frame;
- unsigned char *data;
- int i, j, k, l, o;
+ struct msgb *msg = NULL;
/* frame shall be sent to upqueue */
if (!(ue = lookup_trau_upqueue(src_e1_ss)))
return -EINVAL;
if (!ue->callref)
return -EINVAL;
- if (memcmp(tf.c_bits, c_bits_check, sizeof(c_bits_check)))
+ if (!memcmp(tf.c_bits, c_bits_check_fr, 5))
+ msg = trau_decode_fr(ue, &tf);
+ else if (!memcmp(tf.c_bits, c_bits_check_efr, 5))
+ msg = trau_decode_efr(ue, &tf);
+ else {
DEBUGPC(DLMUX, "illegal trau (C1-C5) %s\n",
- osmo_hexdump(tf.c_bits, sizeof(c_bits_check)));
- msg = msgb_alloc(sizeof(struct gsm_data_frame) + 33,
- "GSM-DATA");
+ osmo_hexdump(tf.c_bits, 5));
+ DEBUGPC(DLMUX, "test trau (C1-C5) %s\n",
+ osmo_hexdump(c_bits_check_efr, 5));
+ return -EINVAL;
+ }
if (!msg)
return -ENOMEM;
-
- frame = (struct gsm_data_frame *)msg->data;
- memset(frame, 0, sizeof(struct gsm_data_frame));
- data = frame->data;
- data[0] = 0xd << 4;
- /* reassemble d-bits */
- i = 0; /* counts bits */
- j = 4; /* counts output bits */
- k = gsm_fr_map[0]-1; /* current number bit in element */
- l = 0; /* counts element bits */
- o = 0; /* offset input bits */
- while (i < 260) {
- data[j/8] |= (tf.d_bits[k+o] << (7-(j%8)));
- if (--k < 0) {
- o += gsm_fr_map[l];
- k = gsm_fr_map[++l]-1;
- }
- i++;
- j++;
- }
- frame->msg_type = GSM_TCHF_FRAME;
- frame->callref = ue->callref;
- msgb_put(msg, sizeof(struct gsm_data_frame) + 33);
trau_tx_to_mncc(ue->net, msg);
return 0;
@@ -276,13 +414,86 @@ int trau_recv_lchan(struct gsm_lchan *lchan, uint32_t callref)
return 0;
}
+static void trau_encode_fr(struct decoded_trau_frame *tf,
+ const unsigned char *data)
+{
+ int i, j, k, l, o;
+
+ /* set c-bits and t-bits */
+ tf->c_bits[0] = 1;
+ tf->c_bits[1] = 1;
+ tf->c_bits[2] = 1;
+ tf->c_bits[3] = 0;
+ tf->c_bits[4] = 0;
+ memset(&tf->c_bits[5], 0, 6);
+ memset(&tf->c_bits[11], 1, 10);
+ memset(&tf->t_bits[0], 1, 4);
+ /* reassemble d-bits */
+ i = 0; /* counts bits */
+ j = 4; /* counts input bits */
+ k = gsm_fr_map[0]-1; /* current number bit in element */
+ l = 0; /* counts element bits */
+ o = 0; /* offset output bits */
+ while (i < 260) {
+ tf->d_bits[k+o] = (data[j/8] >> (7-(j%8))) & 1;
+ if (--k < 0) {
+ o += gsm_fr_map[l];
+ k = gsm_fr_map[++l]-1;
+ }
+ i++;
+ j++;
+ }
+}
+
+static void trau_encode_efr(struct decoded_trau_frame *tf,
+ const unsigned char *data)
+{
+ int i, j;
+ ubit_t check_bits[26];
+
+ /* set c-bits and t-bits */
+ tf->c_bits[0] = 1;
+ tf->c_bits[1] = 1;
+ tf->c_bits[2] = 0;
+ tf->c_bits[3] = 1;
+ tf->c_bits[4] = 0;
+ memset(&tf->c_bits[5], 0, 6);
+ memset(&tf->c_bits[11], 1, 10);
+ memset(&tf->t_bits[0], 1, 4);
+ /* reassemble d-bits */
+ tf->d_bits[0] = 1;
+ for (i = 1, j = 4; i < 39; i++, j++)
+ tf->d_bits[i] = (data[j/8] >> (7-(j%8))) & 1;
+ efr_parity_bits_1(check_bits, tf->d_bits);
+ osmo_crc8gen_set_bits(&gsm0860_efr_crc3, check_bits, 26,
+ tf->d_bits + 39);
+ for (i = 42, j = 42; i < 95; i++, j++)
+ tf->d_bits[i] = (data[j/8] >> (7-(j%8))) & 1;
+ efr_parity_bits_2(check_bits, tf->d_bits);
+ osmo_crc8gen_set_bits(&gsm0860_efr_crc3, check_bits, 12,
+ tf->d_bits + 95);
+ for (i = 98, j = 95; i < 148; i++, j++)
+ tf->d_bits[i] = (data[j/8] >> (7-(j%8))) & 1;
+ efr_parity_bits_3(check_bits, tf->d_bits);
+ osmo_crc8gen_set_bits(&gsm0860_efr_crc3, check_bits, 8,
+ tf->d_bits + 148);
+ for (i = 151, j = 145; i < 204; i++, j++)
+ tf->d_bits[i] = (data[j/8] >> (7-(j%8))) & 1;
+ efr_parity_bits_4(check_bits, tf->d_bits);
+ osmo_crc8gen_set_bits(&gsm0860_efr_crc3, check_bits, 12,
+ tf->d_bits + 204);
+ for (i = 207, j = 198; i < 257; i++, j++)
+ tf->d_bits[i] = (data[j/8] >> (7-(j%8))) & 1;
+ efr_parity_bits_5(check_bits, tf->d_bits);
+ osmo_crc8gen_set_bits(&gsm0860_efr_crc3, check_bits, 8,
+ tf->d_bits + 257);
+}
+
int trau_send_frame(struct gsm_lchan *lchan, struct gsm_data_frame *frame)
{
uint8_t trau_bits_out[TRAU_FRAME_BITS];
struct gsm_e1_subslot *dst_e1_ss = &lchan->ts->e1_link;
struct subch_mux *mx;
- int i, j, k, l, o;
- unsigned char *data = frame->data;
struct decoded_trau_frame tf;
mx = e1inp_get_mux(dst_e1_ss->e1_nr, dst_e1_ss->e1_ts);
@@ -291,30 +502,10 @@ int trau_send_frame(struct gsm_lchan *lchan, struct gsm_data_frame *frame)
switch (frame->msg_type) {
case GSM_TCHF_FRAME:
- /* set c-bits and t-bits */
- tf.c_bits[0] = 1;
- tf.c_bits[1] = 1;
- tf.c_bits[2] = 1;
- tf.c_bits[3] = 0;
- tf.c_bits[4] = 0;
- memset(&tf.c_bits[5], 0, 6);
- memset(&tf.c_bits[11], 1, 10);
- memset(&tf.t_bits[0], 1, 4);
- /* reassemble d-bits */
- i = 0; /* counts bits */
- j = 4; /* counts input bits */
- k = gsm_fr_map[0]-1; /* current number bit in element */
- l = 0; /* counts element bits */
- o = 0; /* offset output bits */
- while (i < 260) {
- tf.d_bits[k+o] = (data[j/8] >> (7-(j%8))) & 1;
- if (--k < 0) {
- o += gsm_fr_map[l];
- k = gsm_fr_map[++l]-1;
- }
- i++;
- j++;
- }
+ trau_encode_fr(&tf, frame->data);
+ break;
+ case GSM_TCHF_FRAME_EFR:
+ trau_encode_efr(&tf, frame->data);
break;
default:
DEBUGPC(DLMUX, "unsupported message type %d\n",
--
1.7.3.4