Re: [RFC PATCH 1/2] audio/mixeng: Fix Clang 'int-conversion' warning

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

On 5/4/20 7:49 AM, Volker Rümelin wrote:
> 
>> Fix by using a 64-bit float for the conversion, before casting
>> back to 32-bit float.
>>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>   audio/mixeng.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/audio/mixeng.c b/audio/mixeng.c
>> index 739a500449..9946bfeaec 100644
>> --- a/audio/mixeng.c
>> +++ b/audio/mixeng.c
>> @@ -271,7 +271,7 @@ f_sample *mixeng_clip[2][2][2][3] = {
>>   #define CONV_NATURAL_FLOAT(x) (x)
>>   #define CLIP_NATURAL_FLOAT(x) (x)
>>   #else
>> -static const float float_scale = UINT_MAX / 2.f;
>> +static const float float_scale = UINT_MAX / 2.;
> 
> I would prefer an explicit cast of UINT_MAX to float. This is what we already have in audio/mixeng_template.h in the conf_* and clip_* functions with FLOAT_MIXENG defined. I think similar functions should look similar.
> 
>>   #define CONV_NATURAL_FLOAT(x) ((x) * float_scale)
>>   
>>   #ifdef RECIPROCAL
> 
> Please don't forget to fix the RECIPROCAL case.
> 
> 
> Btw. the problem was reported here:
> https://lists.nongnu.org/archive/html/qemu-devel/2020-03/msg02270.html

Ah I missed that, I now feel safer knowing developers who understand 
this code are already trying to fix it, thanks Volker!

> 
> With best regards,
> Volker
> 
>