<div dir="ltr"> <div class="gmail_extra"> <div class="gmail_quote">On Tue, Nov 18, 2014 at 3:23 AM, Iago Toral Quiroga <<a href="mailto:itoral@igalia.com" target="_blank">itoral@igalia.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">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. </blockquote><div> </div><div>If this is being split into an "in-place" and "different pointers" version, I think using the "restrict" keyword would be useful here to improve the performance. Then, the in-place one cannot be implemented as copy(p,p,n), but the code isn't overly complicated.</div><div> </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> 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 <a href="mailto:mesa-dev@lists.freedesktop.org" target="_blank">mesa-dev@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/mesa-dev" target="_blank">http://lists.freedesktop.org/mailman/listinfo/mesa-dev</a> </blockquote></div> </div></div>