Review at https://gerrit.osmocom.org/4676
gsm0503_coding.c: Use majority vote in tch_efr_unreorder()
The EFR coding contains some repeated bits. In case there are
transmission errors, some bits may of course get corrupted. It looks
like there's an improvement can be made by taking a majority vote on
those "repetition bits", i.e. if 2 out of 3 bits are the same, then use
that instead of expecting to match all 3 bits.
See 3GPP TS 45.003 Section 3.1.1.3 for reference.
Change-Id: I2a28a4d7fb82aed4d39fe8efeea702effdba3858
---
M src/coding/gsm0503_coding.c
1 file changed, 3 insertions(+), 3 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/76/4676/1
diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c
index c4bdb81..639d2df 100644
--- a/src/coding/gsm0503_coding.c
+++ b/src/coding/gsm0503_coding.c
@@ -1743,16 +1743,16 @@
memcpy(s, w, 71);
sum = s[69] + w[71] + w[72];
- s[69] = (sum > 2);
+ s[69] = (sum >= 2);
memcpy(s + 71, w + 73, 50);
sum = s[119] + w[123] + w[124];
- s[119] = (sum > 2);
+ 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[222] + w[230] + w[231];
- s[222] = (sum > 2);
+ s[222] = (sum >= 2);
memcpy(s + 224, w + 232, 20);
memcpy(p, w + 252, 8);
}
--
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I2a28a4d7fb82aed4d39fe8efeea702effdba3858
Gerrit-PatchSet: 1
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Owner: Harald Welte <lafo...@gnumonks.org>
