[FFmpeg-devel] [PATCH] Use posix_memalign() instead of memalign()
Tue Oct 7 19:01:13 CEST 2008
On Tue, Oct 7, 2008 at 4:24 AM, M?ns Rullg?rd <mans at mansr.com> wrote:
> "Ramiro Polla" <ramiro.polla at gmail.com> writes:
>> On Sun, Sep 28, 2008 at 10:17 AM, M?ns Rullg?rd <mans at mansr.com> wrote:
>>> Diego 'Flameeyes' Petten? <flameeyes at gmail.com> writes:
>>>> While on GLIBC the memalign() function is declared in malloc.h, on
>>>> OpenSolaris its definiton is in stdlib.h; include the file so that an
>>>> implicit declaration can be avoided.
>>>> libavutil/mem.c | 1 +
>>>> 1 files changed, 1 insertions(+), 0 deletions(-)
>>>> diff --git a/libavutil/mem.c b/libavutil/mem.c
>>>> index 960074c..da75638 100644
>>>> --- a/libavutil/mem.c
>>>> +++ b/libavutil/mem.c
>>>> @@ -34,6 +34,7 @@
>>>> #ifdef HAVE_MALLOC_H
>>>> #include <malloc.h>
>>>> +#include <stdlib.h>
>>>> /* you can redefine av_malloc and av_free in your project to use your
>>>> memory allocator. You do not need to suppress this file because the
>>> #including stdlib.h obviously can't do any harm, it being a standard
>>> There is, however, a deeper issue here: memalign() is not
>>> defined by any standard, and some systems that have it provide no
>>> means to free such allocations. Is there any reason we can't use the
>>> standard posix_memalign() instead?
>> Attached patch should spark some discussion...
>> Index: libavutil/mem.c
>> --- libavutil/mem.c (revision 15575)
>> +++ libavutil/mem.c (working copy)
>> @@ -35,6 +35,10 @@
>> #include <malloc.h>
> #include <malloc.h> wouldn't be needed with posix_memalign(), but see
Which systems use malloc.h?
>> +#ifdef HAVE_POSIX_MEMALIGN
>> +#include <stdlib.h>
> It is always save to #include <stdlib.h>
Now I see that the stdlib.h include comes from common.h.
And another thing, I remember there was some discussion regarding
whether we should include only the necessary files or whether it was
ok to just include common.h everywhere, but I forgot the outcome.
Is mem.c a case where it would be ok to:
>> /* you can redefine av_malloc and av_free in your project to use your
>> memory allocator. You do not need to suppress this file because the
>> linker will do it automatically */
>> @@ -57,8 +61,9 @@
>> diff= ((-(long)ptr - 1)&15) + 1;
>> ptr = (char*)ptr + diff;
>> ((char*)ptr)[-1]= diff;
>> -#elif defined (HAVE_MEMALIGN)
>> - ptr = memalign(16,size);
>> +#elif defined (HAVE_POSIX_MEMALIGN)
>> + if(posix_memalign(&ptr,16,size))
>> + ptr = NULL;
> It might make sense to use memalign() as a fall-back for old BSD
> systems and the like without posix_memalign().
Would that be a manually entered list like is done for need_memalign?
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