Hi,
In upgrading our pixman package I discovered that we're carrying two
non-trivial patches. One was previously rejected on the list so I'll
do some more research and come back to that, but the other one simply
adds a generic implementation of pixman_blt. I've attached the patch,
refreshed for 0.32.4
>From what I can tell if the processor doesn't support any of the
vector hardware operations then the pixman_blt operation will simply
run out of implementations and return FALSE. We test our software on
x86/PPC/MIPS/ARM machines emulated in qemu, so I wouldn't be surprised
if that happened on PPC, and maybe MIPS/ARM depending on the exact
machine configuration.
So, has a generic blt implementation been rejected in the past, should
this patch be reviewed and merged, or is it redundant and I can delete
it?
Cheers,
Ross
Generic C implementation of pixman_blt with overlapping support
This was ported from meta-oe's patch [1]:
Uses memcpy/memmove functions to copy pixels, can handle the
case when both source and destination areas are in the same
image (this is useful for scrolling).
It is assumed that copying direction is only important when
using the same image for both source and destination (and
src_stride == dst_stride). Copying direction is undefined
for the images with different source and destination stride
which happen to be in the overlapped areas (but this is an
unrealistic case anyway).
[1] http://cgit.openembedded.org/meta-openembedded/tree/meta-oe/recipes-graphics/xorg-lib/pixman-0.26.2/0008-Generic-C-implementation-of-pixman_blt-with-overlapp.patch
Upstream-Status: Pending
Signed-off-by: Andreas Müller <[email protected]>
Signed-off-by: Constantin Musca <[email protected]>
Index: pixman-0.28.0/pixman/pixman-general.c
===================================================================
--- pixman-0.28.0.orig/pixman/pixman-general.c
+++ pixman-0.28.0/pixman/pixman-general.c
@@ -214,6 +214,41 @@ static const pixman_fast_path_t general_
{ PIXMAN_OP_NONE }
};
+static pixman_bool_t
+general_blt (pixman_implementation_t *imp,
+ uint32_t * src_bits,
+ uint32_t * dst_bits,
+ int src_stride,
+ int dst_stride,
+ int src_bpp,
+ int dst_bpp,
+ int src_x,
+ int src_y,
+ int dest_x,
+ int dest_y,
+ int width,
+ int height)
+{
+ uint8_t *dst_bytes = (uint8_t *)dst_bits;
+ uint8_t *src_bytes = (uint8_t *)src_bits;
+ int bpp;
+
+ if (src_bpp != dst_bpp || src_bpp & 7)
+ return FALSE;
+
+ bpp = src_bpp >> 3;
+ width *= bpp;
+ src_stride *= 4;
+ dst_stride *= 4;
+ pixman_blt_helper (src_bytes + src_y * src_stride + src_x * bpp,
+ dst_bytes + dest_y * dst_stride + dest_x * bpp,
+ src_stride,
+ dst_stride,
+ width,
+ height);
+ return TRUE;
+}
+
pixman_implementation_t *
_pixman_implementation_create_general (void)
{
@@ -222,5 +257,6 @@ _pixman_implementation_create_general (v
_pixman_setup_combiner_functions_32 (imp);
_pixman_setup_combiner_functions_float (imp);
+ imp->blt = general_blt;
imp->iter_info = general_iters;
Index: pixman-0.28.0/pixman/pixman-private.h
===================================================================
--- pixman-0.28.0.orig/pixman/pixman-private.h
+++ pixman-0.28.0/pixman/pixman-private.h
@@ -1109,6 +1109,45 @@ void pixman_timer_register (pixman_timer
#endif /* PIXMAN_TIMERS */
+/* a helper function, can blit 8-bit images with src/dst overlapping support */
+static inline void
+pixman_blt_helper (uint8_t *src_bytes,
+ uint8_t *dst_bytes,
+ int src_stride,
+ int dst_stride,
+ int width,
+ int height)
+{
+ /*
+ * The second part of this check is not strictly needed, but it prevents
+ * unnecessary upside-down processing of areas which belong to different
+ * images. Upside-down processing can be slower with fixed-distance-ahead
+ * prefetch and perceived as having more tearing.
+ */
+ if (src_bytes < dst_bytes + width &&
+ src_bytes + src_stride * height > dst_bytes) {
+ src_bytes += src_stride * height - src_stride;
+ dst_bytes += dst_stride * height - dst_stride;
+ dst_stride = -dst_stride;
+ src_stride = -src_stride;
+
+ /* Horizontal scrolling to the left needs memmove */
+ if (src_bytes + width > dst_bytes) {
+ while (--height >= 0) {
+ memmove (dst_bytes, src_bytes, width);
+ dst_bytes += dst_stride;
+ src_bytes += src_stride;
+ }
+ return;
+ }
+ }
+ while (--height >= 0) {
+ memcpy (dst_bytes, src_bytes, width);
+ dst_bytes += dst_stride;
+ src_bytes += src_stride;
+ }
+}
+
#endif /* __ASSEMBLER__ */
#endif /* PIXMAN_PRIVATE_H */
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