No good reason really, simply that the original functions seemed simpler
for the case of in-place swapping since you don't have to pass the dst
parameter explicitly, so I figured there was a marginal gain in letting
them stay, specially since their implementation is just an inline call
to the other version. Do you prefer the other solution?
Iago
On Wed, 2014-11-19 at 12:00 -0800, Jason Ekstrand wrote:
> Any reason why you added 2 new functions, instead of just altering the
> ones we have and updating where they are used?
>
>
> On Tue, Nov 18, 2014 at 1:23 AM, Iago Toral Quiroga
> <ito...@igalia.com> wrote:
> We have _mesa_swap{2,4} but these do in-place byte-swapping
> only. The new
> functions receive an extra parameter so we can swap bytes on a
> source
> input array and store the results in a (possibly different)
> destination
> array.
>
> This is useful to implement byte-swapping in pixel uploads,
> since in this
> case we need to swap bytes on the src data which is owned by
> the
> application so we can't do an in-place byte swap.
> ---
> src/mesa/main/image.c | 25 +++++++++++++++++--------
> src/mesa/main/image.h | 10 ++++++++--
> 2 files changed, 25 insertions(+), 10 deletions(-)
>
> diff --git a/src/mesa/main/image.c b/src/mesa/main/image.c
> index 4ea5f04..9ad97c5 100644
> --- a/src/mesa/main/image.c
> +++ b/src/mesa/main/image.c
> @@ -41,36 +41,45 @@
>
>
> /**
> - * Flip the order of the 2 bytes in each word in the given
> array.
> + * Flip the order of the 2 bytes in each word in the given
> array (src) and
> + * store the result in another array (dst). For in-place
> byte-swapping this
> + * function can be called with the same array for src and
> dst.
> *
> - * \param p array.
> + * \param dst the array where byte-swapped data will be
> stored.
> + * \param src the array with the source data we want to
> byte-swap.
> * \param n number of words.
> */
> void
> -_mesa_swap2( GLushort *p, GLuint n )
> +_mesa_swap2_copy( GLushort *dst, GLushort *src, GLuint n )
> {
> GLuint i;
> for (i = 0; i < n; i++) {
> - p[i] = (p[i] >> 8) | ((p[i] << 8) & 0xff00);
> + dst[i] = (src[i] >> 8) | ((src[i] << 8) & 0xff00);
> }
> }
>
>
>
> /*
> - * Flip the order of the 4 bytes in each word in the given
> array.
> + * Flip the order of the 4 bytes in each word in the given
> array (src) and
> + * store the result in another array (dst). For in-place
> byte-swapping this
> + * function can be called with the same array for src and
> dst.
> + *
> + * \param dst the array where byte-swapped data will be
> stored.
> + * \param src the array with the source data we want to
> byte-swap.
> + * \param n number of words.
> */
> void
> -_mesa_swap4( GLuint *p, GLuint n )
> +_mesa_swap4_copy( GLuint *dst, GLuint *src, GLuint n )
> {
> GLuint i, a, b;
> for (i = 0; i < n; i++) {
> - b = p[i];
> + b = src[i];
> a = (b >> 24)
> | ((b >> 8) & 0xff00)
> | ((b << 8) & 0xff0000)
> | ((b << 24) & 0xff000000);
> - p[i] = a;
> + dst[i] = a;
> }
> }
>
> diff --git a/src/mesa/main/image.h b/src/mesa/main/image.h
> index abd84bf..79c6e68 100644
> --- a/src/mesa/main/image.h
> +++ b/src/mesa/main/image.h
> @@ -33,10 +33,16 @@ struct gl_context;
> struct gl_pixelstore_attrib;
>
> extern void
> -_mesa_swap2( GLushort *p, GLuint n );
> +_mesa_swap2_copy( GLushort *dst, GLushort *src, GLuint n );
>
> extern void
> -_mesa_swap4( GLuint *p, GLuint n );
> +_mesa_swap4_copy( GLuint *dst, GLuint *src, GLuint n );
> +
> +static inline void
> +_mesa_swap2( GLushort *p, GLuint n ) { _mesa_swap2_copy(p, p,
> n); }
> +
> +static inline void
> +_mesa_swap4( GLuint *p, GLuint n ) { _mesa_swap4_copy(p, p,
> n); }
>
> extern GLintptr
> _mesa_image_offset( GLuint dimensions,
> --
> 1.9.1
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
>
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