FreeCalypso > hg > gsm-codec-lib
view libtwamr/tls_flags.c @ 604:54f0f1b74c25
libgsmhr1 TFO: require BFI=0 and SID=0 for homing
In order for a received frame to be recognized as DHF, we need
not only the correct bit pattern, but also BFI=0 and SID=0.
The BFI=0 requirement should be obvious, while the SID=0 requirement
is needed only for HR codec. With FR and EFR, SID classification
comes from the payload bits and no separate check is needed -
but in HR we get an out-of-band SID ternary flag. When SID=1,
no payload bits are used at all; when SID=2, we use only the first
33 bits of the payload. Therefore, it is proper to conditionalize
DHF acceptance on SID=0.
We already implemented this logic in the just finished full decoder;
now bring TFO code into agreement.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Thu, 04 Dec 2025 19:40:35 +0000 |
| parents | dfb1f86541b2 |
| children |
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/* * Unfortunately the code we got from ETSI makes heavy use of two global * Boolean flags named Carry and Overflow that function like equally named * processor state flags on many CPU architectures. They are not part * of persistent codec session state for either the encoder or the decoder, * instead they are "short-term" globals much like UNIX errno. * * Given this unfortunate reality plus the natural desire to make our * AMR library thread-safe (a transcoding MGW handling a large volume of * simultaneous calls is exactly the kind of application that would benefit * from utilitizing all CPU cores), our current workaround is to use * thread-local storage. */ #include "typedef.h" #include "namespace.h" __thread Flag Carry, Overflow;
