fixeria has uploaded this change for review.
csd_v110_rtp_encode(): properly set E1/E2/E3 bits
The E1/E2/E3 bits are set based on out-of-band knowledge of the
current user data rate. The actual bit values are defined in
3GPP TS 44.021, Figure 4 "Coding of data rates".
TODO: this is only valid for transparent services,
for non-transparent services see 3GPP TS 48.020.
TODO: lchan->csd_mode is never set to the actual CSD mode...
Change-Id: I1a14597dff746cf975140b294400a2cc05badccd
Related: OS#1572
---
M include/osmo-bts/lchan.h
M src/common/csd_v110.c
2 files changed, 38 insertions(+), 3 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/34/33934/1
diff --git a/include/osmo-bts/lchan.h b/include/osmo-bts/lchan.h
index a0e99bf..05c395a 100644
--- a/include/osmo-bts/lchan.h
+++ b/include/osmo-bts/lchan.h
@@ -75,15 +75,17 @@
};
enum lchan_csd_mode {
- LCHAN_CSD_M_NT,
+ LCHAN_CSD_M_NT = 0,
LCHAN_CSD_M_T_1200_75,
LCHAN_CSD_M_T_600,
LCHAN_CSD_M_T_1200,
LCHAN_CSD_M_T_2400,
+ LCHAN_CSD_M_T_4800,
LCHAN_CSD_M_T_9600,
LCHAN_CSD_M_T_14400,
LCHAN_CSD_M_T_29000,
LCHAN_CSD_M_T_32000,
+ _LCHAN_CSD_M_NUM,
};
/* State of the SAPIs in the lchan */
diff --git a/src/common/csd_v110.c b/src/common/csd_v110.c
index 8870732..0061935 100644
--- a/src/common/csd_v110.c
+++ b/src/common/csd_v110.c
@@ -34,6 +34,19 @@
#define DATA_RATE(type, mode) ((type << 8) | mode)
+/* 3GPP TS 44.021, Figure 4: Coding of data rates (E1/E2/E3 bits) */
+static const uint8_t e1e2e3_map[_LCHAN_CSD_M_NUM][3] = {
+ [LCHAN_CSD_M_T_600] = { 1, 0, 0 },
+ [LCHAN_CSD_M_T_1200] = { 0, 1, 0 },
+ [LCHAN_CSD_M_T_2400] = { 1, 1, 0 },
+ [LCHAN_CSD_M_T_4800] = { 0, 1, 1 },
+ [LCHAN_CSD_M_T_9600] = { 0, 1, 1 },
+/* [LCHAN_CSD_M_T_19200] = { 0, 1, 1 }, */
+/* [LCHAN_CSD_M_T_38400] = { 0, 1, 1 }, */
+ [LCHAN_CSD_M_T_14400] = { 1, 0, 1 },
+/* [LCHAN_CSD_M_T_28800] = { 1, 0, 1 }, */
+};
+
static int lchan_data_rate(const struct gsm_lchan *lchan,
size_t *num_blocks,
size_t *num_bits)
@@ -98,8 +111,10 @@
else /* num_bits == 36 */
osmo_csd_3k6_decode_frame(&df, &data[i * 36], 36);
- /* FIXME: E1 .. E3 must be set by out-of-band knowledge! */
- memset(&df.e_bits[0], 0, 3);
+ /* E1 .. E3 must set by out-of-band knowledge */
+ df.e_bits[0] = e1e2e3_map[lchan->csd_mode][0];
+ df.e_bits[1] = e1e2e3_map[lchan->csd_mode][1];
+ df.e_bits[2] = e1e2e3_map[lchan->csd_mode][2];
osmo_v110_encode_frame(&ra_bits[i * 80], 80, &df);
}
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