Re: [hatari-devel] Falcon left-right sound swapper bug?

[David Savinkoff <dsavnkff@xxxxxxxxx>]

----- Eero Tamminen wrote:
> Hi,
> 
> On torstai 17 huhtikuu 2014, David Savinkoff wrote:
> > crossbar.c is the only file that has:
> > dac.readPosition :: dac.writePosition
> > and:
> > adc2dac_readBufferPosition :: adc2dac_writeBufferPosition
> > 
> > These circular buffer indexes must check that they do not over-run each
> > other.
> > 
> > dmaSnd.c maintains the circular buffer indexes with:
> > static void DmaSnd_FIFO_Refill(void);
> > static Sint8 DmaSnd_FIFO_PullByte(void);
> > 
> > crossbar.c has incomplete functions:
> > void Crossbar_GetMicrophoneDatas(Sint16 *micro_bufferL, Sint16
> > *micro_bufferR, Uint32 microBuffer_size); static void
> > Crossbar_SendDataToDAC(Sint16 value, Uint16 sample_pos); void
> > Crossbar_GenerateSamples(int nMixBufIdx, int nSamplesToGenerate);
> 
> There's following old bug in Hatari Crossbar DMA code:
> http://listengine.tuxfamily.org/lists.tuxfamily.org/hatari-
> devel/2012/02/msg00082.html
> 
> It doesn't check the indeces given by emulated code
> which is really bad because emulated code can then
> corrupt Hatari's own memory.  That might then have also
> other effects.
> 
> 
> 	- Eero
> 
The 'read buffer position' and 'write buffer position' pointers
stay within the buffer's allocated space, but each are unaware
of the others existence and can become unsynchronized.