dsound mixer speedup

[Robert Reif]

Joerg Mayer wrote:

>On Thu, Aug 12, 2004 at 12:24:20AM -0400, Robert Reif wrote:
>  
>
>>Speed up mixing and unmixing by moving sample size and buffer
>>wrap tests to outside the loop.  The code is not as compact or 
>>pretty
>>but it should be faster.
>>    
>>
>
>Just out of curiosity: *IS* it really faster? Maybe gcc already did
>the optimization?
>
> Ciao
>   Joerg
>
>  
>
for both 8 and 16 bit samples (no optimization)
    the new code executes in about 48% of the time of the old code 
(twice as fast)

8 bit -O3
   75% of old code (1.5 times as fast)

16 bit -O3
  50% of old code (twice as fast)

This is with a 32k buffer and a 1k chunk size.