On 04/01/2013 02:13 PM, Peter Meerwald wrote:
> Hello Tanu,
>
> thanks for reviewing!
>
>>>> + case PA_SAMPLE_S16NE:
>>>> + {
>>>> + int16_t *d = (int16_t *) dst, *s = (int16_t *) src;
>>>> +
>>>> + for (i = n>> 2; i> 0; i--) {
>>>> + d[0] += (s[0] + s[1])/2;
>>>> + d[1] += (s[2] + s[3])/2;
>>>> + d[2] += (s[4] + s[5])/2;
>>>> + d[3] += (s[6] + s[7])/2;
>>>
>>> You probably meant '=', not '+='?
>>>
>>> Also, s[0] + s[1] can overflow, so the inputs should be divided
>>> individually before summing.
>>
>> Or the inputs could be cast to uint32_t, which I guess would be better
>> than dividing multiple times.
>
> it should be '=' obviously -- will fix and repost shortly
>
> I think (s[0] + s[1])/2 is correct; at least as long as sizeof(int)>
> sizeof(short); short gets promoted to int -- see 'integer promotion in
> C99'; also my compiler thinks above is correct :)
It seems that you're right. I would still prefer explicit casts, because
few people bother to memorize the C promotion rules.
--
Tanu
