mmdevapi: Correctly convert UINT32 to INT64

Andrew,

thank you very much for finding a bug in my code.

I'll have to meditate signed/unsigned conversions for the next months.

Perhaps it's my lack of familiarity with the MS-Windows API that had
me not find a signed equivalent of UINT32. Indeed there's none in
windef.h. So I choose 'long'. But now I see basestd.h defines LONG32.

INT64 is not appropriate. getbuf_last should be of the same size than
the other frame holding types.  I once wrote a patch to turn all
#frame holding entities from UINT64 into 32.  Please rewrite the patch
to use the LONG32 type, then you'll need no surprising cast.

If the loss of 1 bit worries you, the solution IMHO is not to go to
INT64 rather than prevent a duration that large in Initialize.  In
shared mode, there's no 2s limit. My tests opened a 10s buffer. I've
not tested anything larger.
LONG32 leaves enough room for 10000 seconds at 200000fps.

Regards,
    Jörg Höhle

[Michael Stefaniuc]

Hello Joerg,

On 01/30/2012 09:46 AM, [e-mail] wrote:
> thank you very much for finding a bug in my code.
>
> I'll have to meditate signed/unsigned conversions for the next months.
>
> Perhaps it's my lack of familiarity with the MS-Windows API that had
> me not find a signed equivalent of UINT32. Indeed there's none in
> windef.h. So I choose 'long'. But now I see basestd.h defines LONG32.

LONG32 is kinda redundant. LONG is 32bit on all Windows versions on 
16bit, 32bit and 64bit Windows.
> INT64 is not appropriate. getbuf_last should be of the same size than
> the other frame holding types.  I once wrote a patch to turn all
> #frame holding entities from UINT64 into 32.  Please rewrite the patch
> to use the LONG32 type, then you'll need no surprising cast.
>
> If the loss of 1 bit worries you, the solution IMHO is not to go to
> INT64 rather than prevent a duration that large in Initialize.  In
> shared mode, there's no 2s limit. My tests opened a 10s buffer. I've
> not tested anything larger.
> LONG32 leaves enough room for 10000 seconds at 200000fps.

bye
    michael

Michael Stefaniuc wrote:
> > But now I see basestd.h defines LONG32.
>
> LONG32 is kinda redundant. LONG is 32bit on all Windows
> versions on 16bit, 32bit and 64bit Windows.

Ah, thank you.  However in our particular case, the value that
getbuf_last is derived from is UINT32, not UINT, so for symmetry,
I still recommend the explicit LONG32.

Regards,
    Jörg Höhle

[Vitaliy Margolen]

On 01/30/2012 03:08 AM, [e-mail] wrote:
> Michael Stefaniuc wrote:
> > > But now I see basestd.h defines LONG32.
> >
> > LONG32 is kinda redundant. LONG is 32bit on all Windows
> > versions on 16bit, 32bit and 64bit Windows.
>
> Ah, thank you.  However in our particular case, the value that
> getbuf_last is derived from is UINT32, not UINT, so for symmetry,
> I still recommend the explicit LONG32.

UINT is the same as UNIT32:

basetsd.h:84 typedef unsigned int     UINT32, *PUINT32;
windef.h:213 typedef unsigned int    UINT,       *PUINT;

Vitaliy.