[Bug 14717] resampled sound is horrible

http://bugs.winehq.org/show_bug.cgi?id=14717

--- Comment #277 from Jörg Höhle  2012-03-08 04:18:39 CST ---
> We increment the buffer's sec_mixpos directly, and "fix" its overflow
> later. _GetCurrentPosition manages to sneak in before we fix it

Choices:

1. Choose another design.  E.g. the lock-less winealsa.drv design
   sketched in bug #29531, comment #7 solely shares held_frames among
   threads, where InterlockedExchangeAdd suffices, there's no need for
   a modulo operation.

2. What about:
    see = This->sec_mixpos;
    repeat {
        old = see;
        new = (see + added) % size;
        see = InterlockedCompareExchange(&This->sec_mixpos,new,old);
    } until (see == old);

You can turn that into an inline InterlockedModuloAdd (except C89 does not say
what exactly happens when see+added < 0, unlike C99 IIRC).  You want to
guarantee that 0 <= new < size, not face new < 0.