Re: [Qemu-devel] [PATCH] audio: fix integer overflow expression

[malc]

On Tue, 31 May 2011, Peter Maydell wrote:

> From: Juha Riihim?ki <address@hidden>
> 
> Fix an integer overflow that can happen for signed 32 bit types
> when using FLOAT_MIXENG. (Note that at the moment this is only true
> when using the MacOSX coreaudio audio driver.)
> 
> Signed-off-by: Juha Riihim?ki <address@hidden>
> Reviewed-by: Peter Maydell <address@hidden>
> ---
> I'm trying to get random patches out of my patch-stack and upstream.
> This one looks "obviously correct" but it only kicks in for MacOSX
> and coreaudio, and I don't have access to that platform to test myself,
> so treat my reviewed-by accordingly.
> 
> This has actually been posted here before, last year:
>  http://patchwork.ozlabs.org/patch/48703/

One nit, only one of the casts is really needed, pick one and i'll apply
it.

> 
>  audio/mixeng_template.h |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/audio/mixeng_template.h b/audio/mixeng_template.h
> index a2d0ef8..e01da0a 100644
> --- a/audio/mixeng_template.h
> +++ b/audio/mixeng_template.h
> @@ -46,7 +46,7 @@ static mixeng_real inline glue (conv_, ET) (IN_T v)
>  #endif
>  #else  /* !RECIPROCAL */
>  #ifdef SIGNED
> -    return nv / (mixeng_real) (IN_MAX - IN_MIN);
> +    return nv / (mixeng_real) ((mixeng_real)IN_MAX - (mixeng_real)IN_MIN);
>  #else
>      return (nv - HALF) / (mixeng_real) IN_MAX;
>  #endif
> @@ -63,7 +63,7 @@ static IN_T inline glue (clip_, ET) (mixeng_real v)
>      }
>  
>  #ifdef SIGNED
> -    return ENDIAN_CONVERT ((IN_T) (v * (IN_MAX - IN_MIN)));
> +    return ENDIAN_CONVERT ((IN_T) (v * ((mixeng_real)IN_MAX - 
> (mixeng_real)IN_MIN)));
>  #else
>      return ENDIAN_CONVERT ((IN_T) ((v * IN_MAX) + HALF));
>  #endif
> 

-- 
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