On Mon, Oct 29, 2012 at 9:20 AM, Måns Rullgård <m...@mansr.com> wrote:
> Alex Converse <alex.conve...@gmail.com> writes:
>
>> On Fri, Oct 26, 2012 at 5:50 PM, Mans Rullgard <m...@mansr.com> wrote:
>>> The C99 standard requires that "the expression that defines the value of
>>> an enumeration constant shall be an integer constant expression that has
>>> a value representable as an int."
>>>
>>> Signed-off-by: Mans Rullgard <m...@mansr.com>
>>> ---
>>> libavformat/mov_chan.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/libavformat/mov_chan.c b/libavformat/mov_chan.c
>>> index 00a2a4b..d7eb528 100644
>>> --- a/libavformat/mov_chan.c
>>> +++ b/libavformat/mov_chan.c
>>> @@ -45,7 +45,7 @@
>>> * do not specify a particular ordering of those channels."
>>> */
>>> enum MovChannelLayoutTag {
>>> - MOV_CH_LAYOUT_UNKNOWN = 0xFFFF0000,
>>> + MOV_CH_LAYOUT_UNKNOWN = ( -1 << 16),
>>
>> Your replacement is undefined:
>>
>> 6.5.7 Bitwise shift operators
>>
>> The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated
>> bits are filled with zeros. If E1 has an unsigned type, the value of
>> the result is E1 × 2^E2 , reduced modulo one more than the maximum
>> value representable in the result type. If E1 has a signed type and
>> nonnegative value, and E1 × 2^E2 is representable in the result type,
>> then that is the resulting value; otherwise, the behavior is
>> undefined.
>
> We shift negative values all the time.
>
That may be the case, but this patch does not "make enum
MovChannelLayoutTag definition standards compliant".
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