[PATCH] dsound: correct the dsound fraglen calculations.

[Reece Dunn]

Hi,

Given a timer delay of 10ms, the fragment size is approximately:
    fraglen = (nSamplesPerSecond * 10 / 1000) * nBlockAlign
    ==> fraglen = (nSamplesPerSecond / 100) * nBlockSize

ALSA uses buffers that are powers of 2, so approximate the size for a
given nSamplesPerSecond.
    (nSamplesPerSecond / 100) < 120 ==> power of 2 =  128
    (nSamplesPerSecond / 100) < 250 ==> power of 2 =  256
    (nSamplesPerSecond / 100) < 800 ==> power of 2 =  512
    (nSamplesPerSecond / 100) > 800 ==> power of 2 = 1024

The numbers on the right-hand side of the < are where the numbers come
from (e.g. 120 is 12000).

This is not a revert as the previous version was. I have corrected the
26000 to 25000 to prevent under calculating for 25600 <
nSamplesPerSecond < 26000, as well as documenting the above logic for
people looking at this in the future (otherwise it is difficult to
know where the values come from).

I have tested this with Puzzle Quest and Warcraft III, confirming that
these play correctly without stuttering.

- Reece
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