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From d65a08904857d87dcd74b87681c9b94390b76eff Mon Sep 17 00:00:00 2001
From: Siarhei Siamashka <siarhei.siamashka@nokia.com>
Date: Tue, 16 Mar 2010 16:55:28 +0100
Subject: [PATCH 8/8] Generic C implementation of pixman_blt with overlapping support
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).
---
pixman/pixman-general.c | 21 ++++++++++++++++++---
pixman/pixman-private.h | 43 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 61 insertions(+), 3 deletions(-)
diff --git a/pixman/pixman-general.c b/pixman/pixman-general.c
index 2ccdfcd..6f7bb34 100644
--- a/pixman/pixman-general.c
+++ b/pixman/pixman-general.c
@@ -227,9 +227,24 @@ general_blt (pixman_implementation_t *imp,
int width,
int height)
{
- /* We can't blit unless we have sse2 or mmx */
-
- return FALSE;
+ 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;
}
static pixman_bool_t
diff --git a/pixman/pixman-private.h b/pixman/pixman-private.h
index cbd48f3..c20d9f0 100644
--- a/pixman/pixman-private.h
+++ b/pixman/pixman-private.h
@@ -10,6 +10,7 @@
#include "pixman.h"
#include <time.h>
+#include <string.h>
#include <assert.h>
#include <stdio.h>
#include <string.h>
@@ -998,4 +999,46 @@ void pixman_timer_register (pixman_timer_t *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 /* PIXMAN_PRIVATE_H */
--
1.6.6.1
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