From 1dd7c84733b20ba776510369e9daba1a822c5b44 Mon Sep 17 00:00:00 2001 From: Sylvain Munaut Date: Thu, 28 Apr 2011 22:30:30 +0200 Subject: core/conv: Only consider error for non-zero soft values If the input value is '0' it should not really affect the error since it's just an indecisive bit. We accept this either an internal '0' (generated via puncture) or as an external '0' (generated via an external puncturing scheme). A real received bit should never be '0', it's always gonna be closer to 1 or the other value ... (thanks to mad@auth.se on the ML for the idea) Signed-off-by: Sylvain Munaut --- src/conv.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'src') diff --git a/src/conv.c b/src/conv.c index cf820a33..70bdffba 100644 --- a/src/conv.c +++ b/src/conv.c @@ -389,9 +389,12 @@ osmo_conv_decode_finish(struct osmo_conv_decoder *decoder, m = 1 << (code->N - 1); /* mask for 'out' bit selection */ for (j=0; jN; j++) { - ov = (out & m) ? -127 : 127; /* sbit_t value for it */ - e = ((int)in_sym[j]) - ov; /* raw error for this bit */ - nae += (e * e) >> 9; /* acc the squared/scaled value */ + int is = (int)in_sym[j]; + if (is) { + ov = (out & m) ? -127 : 127; /* sbit_t value for it */ + e = is - ov; /* raw error for this bit */ + nae += (e * e) >> 9; /* acc the squared/scaled value */ + } m >>= 1; /* next mask bit */ } -- cgit v1.2.3