[PATCH] dsound: rework ugly mixer logic

[Maarten Lankhorst]

Op 31-12-12 20:01, Andrew Eikum schreef:
> On Mon, Dec 31, 2012 at 07:03:31PM +0100, Maarten Lankhorst wrote:
>> Op 31-12-12 17:59, Andrew Eikum schreef:
>>> On Sat, Dec 29, 2012 at 01:24:03AM +0100, Maarten Lankhorst wrote:
>>>> +	if(!maxq){
>>>> +		/* nothing to do! */
>>>> +		LeaveCriticalSection(&device->mixlock);
>>>> +		return;
>>>>  	}
>>> This was removed in 8ba4090fc304993. It breaks starting the device in
>>> some situations (write primary mode iirc).
>> Writeprimary dsound tests still worked for me,  I don't particulary care though, if you want I'll zap it.
>> After rework fail it should no longer matter..
>>
> Zaxxon (see Bug 30836) shows the problem on some, but not all,
> systems.  Anyway, PerformMix() does more than just mix and write data,
> so returning early only because we have no frames to write is not
> always correct.
>
>>>> +		if (native) {
>>>> +			void *buffer = NULL;
>>>> +
>>>> +			hr = IAudioRenderClient_GetBuffer(device->render, maxq / block, (void*)&buffer);
>>>> +			if(FAILED(hr)){
>>>> +				WARN("GetBuffer failed: %08x\n", hr);
>>>> +				LeaveCriticalSection(&device->mixlock);
>>>> +				return;
>>>> +			}
>>> I think this (mixing directly to RenderClient and skipping WaveQueue)
>>> could be split into a separate patch.
>> Hate to sound like a broken record here, but the whole mixer logic breaks if you touch that code. :/
>>
> Really? It looks like an optimization to me: mix directly into the
> RenderClient buffer instead of to the intermediary buffer if the
> target format is float. What breaks if we use the intermediary buffer
> in every case?
>
I suppose the if native branch could be taken out, but that's not nearly as interesting as the other
changes I was making in that function, and not nearly as likely to mess up anything.

~Maarten