[vlc-devel] [PATCH v3 01/24] picture: add helpers for picture chaining

[Thomas Guillem]

On Mon, Sep 21, 2020, at 08:29, Steve Lhomme wrote:
> Picture chains are used either to keep a list of picture (in FIFO order) or to
> attach a picture to another and return them all at once (filters).
> ---
>  include/vlc_picture.h | 94 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 94 insertions(+)
> 
> diff --git a/include/vlc_picture.h b/include/vlc_picture.h
> index 7bb9ee5083c..ded7f0df81d 100644
> --- a/include/vlc_picture.h
> +++ b/include/vlc_picture.h
> @@ -167,6 +167,100 @@ static inline vlc_video_context* 
> picture_GetVideoContext(picture_t *pic)
>      return pic->context ? pic->context->vctx : NULL;
>  }
>  
> +/**
> + * picture chaining helpers
> + */
> +
> +/**
> + * Pop the chain from a picture chain.
> + *
> + * The next picture in the chain becomes the front of the picture 
> chain.
> + *
> + * \return the front of the picture chain, with other pictures still 
> chained
> + */
> +static inline picture_t * vlc_picture_chain_PopChain(picture_t **chain)

Do we really need this PopChain ?
You are returning the whole chain and yet you keep it in chain. This feels dangerous.

> +{
> +    picture_t *front = *chain;
> +    if (front)
> +        *chain = front->p_next;
> +    return front;
> +}
> +
> +/**
> + * Pop the front of a picture chain.
> + *
> + * The next picture in the chain becomes the front of the picture 
> chain.
> + *
> + * \return the front of the picture chain (the picture itself)
> + */
> +static inline picture_t * vlc_picture_chain_PopFront(picture_t **chain)
> +{
> +    picture_t *front = *chain;
> +    if (front)
> +    {
> +        *chain = front->p_next;
> +        // unlink the front picture from the rest of the chain
> +        front->p_next = NULL;
> +    }
> +    return front;
> +}
> +
> +/**
> + * Append a picture chain to a picture chain.
> + */
> +static inline void vlc_picture_chain_AppendChain(picture_t *chain, 
> picture_t *tail)
> +{
> +    chain->p_next = tail;
> +}
> +
> +/**
> + * Append a picture to a picture chain.
> + *
> + * \param chain the picture chain pointer
> + * \param pic the picture to append to the chain
> + *
> + * \return the new tail of the picture chain
> + */
> +VLC_USED
> +static inline picture_t * vlc_picture_chain_Append(picture_t *chain, 
> picture_t *pic)
> +{
> +    chain->p_next = pic;
> +    pic->p_next = NULL; // we're appending a picture, not a chain
> +    return pic;
> +}
> +
> +/**
> + * Add a picture at the front of a picture chain.
> + *
> + * The added picture becomes the front of the picture chain.
> + */
> +static inline void vlc_picture_chain_Prepend(picture_t **chain, 
> picture_t *pic)
> +{
> +    pic->p_next = *chain;
> +    *chain = pic;
> +}
> +
> +/**
> + * Check whether a picture has other pictures linked
> + */
> +static inline bool picture_HasChainedPics(const picture_t *pic)
> +{
> +    return pic->p_next != NULL;
> +}
> +
> +/**
> + * Reset a picture chain.
> + *
> + * \return the picture chain that was contained in the picture
> + */
> +static inline picture_t * picture_GetAndResetChain(picture_t *pic)
> +{
> +    picture_t *chain = pic->p_next;
> +    pic->p_next = NULL;
> +    return chain;
> +}
> +
> +
>  /**
>   * This function will create a new picture.
>   * The picture created will implement a default release management 
> compatible
> -- 
> 2.26.2
> 
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