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
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