[MPlayer-dev-eng] Sign extension bug in stream_read_qword_le

[Loren Merritt]

On Sun, 19 Aug 2007, Reimar Döffinger wrote:
> On Sun, Aug 19, 2007 at 12:30:41AM +0200, Sean Veers wrote:
>> --- mplayer-1.0-rc1svn20070812/stream/stream.h  2007-08-12
>> +++ mplayer-1.0-rc1svn20070812/stream/stream.h  2007-08-18
>> @@ -189,7 +189,7 @@ inline static uint64_t stream_read_qword_le
>>    y = stream_read_char(s);
>>    y|=stream_read_char(s)<<8;
>>    y|=stream_read_char(s)<<16;
>> -  y|=stream_read_char(s)<<24;
>> +  y|=(uint32_t)stream_read_char(s)<<24;
>>    y|=(uint64_t)stream_read_char(s)<<32;
>>    y|=(uint64_t)stream_read_char(s)<<40;
>>    y|=(uint64_t)stream_read_char(s)<<48;
>
> I'd propose replacing this by
> return stream_read_dword_le(s) | ((uint64_t)stream_read_dword_le(s) << 32);
>
> (untested though).
> Or the same with keeping y if you consider it more readable.

You need to keep y. Otherwise the compiler is allowed to evaluate the 
arguments of | in any order.

--Loren Merritt