PVS-Studio warning V610 for libfaac

static int WriteTNSData(....)
{
  ...
  unsignedIndex = (unsigned long) (
    tnsFilterPtr->index[i])&(~(~0<<bitsToTransmit));
  ...
}

This suspicious code was found in libfaac project by PVS-Studio static code analyzer.
Warning message is:
V610 Undefined behavior. Check the shift operator '<<. The left operand '~0' is negative. libfaac bitstream1.c 796

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