winmm WAVE_MAPPER patch

[Robert Reif]

This problem was found while looking at the winetest results.
Windows returns an error when asked to get the capabilities of
the default device when there are no devices present.  This makes
sense because you have to have at least one device to have a
default one.

Wine on the other hand doesn't return an error when there are no
devices.  I haven't looked at the data it returns but it must be
uninitialized garbage because there is no device to return the
capabilities of.

After stepping through the code, the line that I changed is the line
that should have returned the error but didn't.   The existing code
basically is:  if the requested device is the default device and the
default device is not set to a valid device, return an error.  Unfortunately
the default device is set to a something (0) in the case where no 
devices are
present. 

The code I added just makes sure there is at least one device
when asking for the default device.  What I assume is happening
is that the default device is not being initialized properly in the
case where there are no devices and that's the real problem. 

The code is real hard to follow because of the macros used and
the -1 array index.  I'm not sure what is really happening so I
just added the extra sanity check to fix the problem.  Thats why
I'm not sure this is the proper fix.

Eric Pouech wrote:

> Robert Reif a écrit :
>
>> Fixes a bug where waveOutGetDevCapsA succeeds with the
>> WAVE_MAPPER device when there are no devices.
>>
>> I'm not sure this is best fix because the code is hard to
>> follow but it does work.
>>
>
> I'm not sure it's the right place to fix it. Did you try on windows 
> what happens with waveOutGetDevCaps(-1, ...) to see what Windows 
> returns for the mapper itself.
> The current code (in mapper) assumes that mapper itself has 
> capabilities (which I'm not sure of). It may well be that we shall 
> return an error (independently on the number of installed drivers), 
> but in that case, proper support is better in the wave mapper it self 
> than in winmm.
>
> A+
>
>