[FFmpeg-devel] [PATCH 01/16] avutil/buffer: add helper to allocate aligned memory

[Rémi Denis-Courmont]

Le torstaina 30. toukokuuta 2024, 22.43.03 EEST averne a écrit :
> This is useful eg. for memory-mapped buffers that need page-aligned memory,
> when dealing with hardware devices
> 
> Signed-off-by: averne <averne381 at gmail.com>
> ---
>  libavutil/buffer.c | 31 +++++++++++++++++++++++++++++++
>  libavutil/buffer.h |  7 +++++++
>  2 files changed, 38 insertions(+)
> 
> diff --git a/libavutil/buffer.c b/libavutil/buffer.c
> index e4562a79b1..b8e357f540 100644
> --- a/libavutil/buffer.c
> +++ b/libavutil/buffer.c
> @@ -16,9 +16,14 @@
>   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
> USA */
> 
> +#include "config.h"
> +
>  #include <stdatomic.h>
>  #include <stdint.h>
>  #include <string.h>
> +#if HAVE_MALLOC_H
> +#include <malloc.h>
> +#endif
> 
>  #include "avassert.h"
>  #include "buffer_internal.h"
> @@ -100,6 +105,32 @@ AVBufferRef *av_buffer_allocz(size_t size)
>      return ret;
>  }
> 
> +AVBufferRef *av_buffer_aligned_alloc(size_t size, size_t align)
> +{
> +    AVBufferRef *ret = NULL;
> +    uint8_t    *data = NULL;
> +
> +#if HAVE_POSIX_MEMALIGN
> +    if (posix_memalign((void **)&data, align, size))

Invalid cast.

> +        return NULL;
> +#elif HAVE_ALIGNED_MALLOC
> +    data = aligned_alloc(align, size);
> +#elif HAVE_MEMALIGN
> +    data = memalign(align, size);
> +#else
> +    return NULL;
> +#endif
> +
> +    if (!data)
> +        return NULL;
> +
> +    ret = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
> +    if (!ret)
> +        av_freep(&data);
> +
> +    return ret;
> +}
> +
>  AVBufferRef *av_buffer_ref(const AVBufferRef *buf)
>  {
>      AVBufferRef *ret = av_mallocz(sizeof(*ret));
> diff --git a/libavutil/buffer.h b/libavutil/buffer.h
> index e1ef5b7f07..8422ec3453 100644
> --- a/libavutil/buffer.h
> +++ b/libavutil/buffer.h
> @@ -107,6 +107,13 @@ AVBufferRef *av_buffer_alloc(size_t size);
>   */
>  AVBufferRef *av_buffer_allocz(size_t size);
> 
> +/**
> + * Allocate an AVBuffer of the given size and alignment.
> + *
> + * @return an AVBufferRef of given size or NULL when out of memory
> + */
> +AVBufferRef *av_buffer_aligned_alloc(size_t size, size_t align);
> +
>  /**
>   * Always treat the buffer as read-only, even when it has only one
>   * reference.


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