In the mmx implementation, check for source == 0 rather than alpha == 0.

Otherwise we compute the incorrect value when the source has zero in
the alpha channel, but non-zero in the color channels.

diff --git a/pixman/pixman-mmx.c b/pixman/pixman-mmx.c
index 957aed2..db87b19 100644 (file)
--- a/pixman/pixman-mmx.c
+++ b/pixman/pixman-mmx.c
@@ -446,7 +446,7 @@ mmxCombineOverU (pixman_implementation_t *imp, pixman_op_t op,
        uint32_t a = ssrc >> 24;
        if (a == 0xff) {
            *dest = ssrc;
-       } else if (a) {
+       } else if (ssrc) {
            __m64 s, sa;
            s = load8888(ssrc);
            sa = expand_alpha(s);
@@ -1447,7 +1447,7 @@ fbCompositeSrc_8888x8888mmx (pixman_implementation_t *imp,
            a = s >> 24;
            if (a == 0xff)
                *dst = s;
-           else if (a) {
+           else if (s) {
                __m64 ms, sa;
                ms = load8888(s);
                sa = expand_alpha(ms);
@@ -2180,7 +2180,7 @@ fbCompositeSrc_8888RevNPx0565mmx (pixman_implementation_t *imp,
 
                *(__m64 *)dst = vdest;
            }
-           else if (a0 | a1 | a2 | a3)
+           else if (s0 | s1 | s2 | s3)
            {
                __m64 vdest = *(__m64 *)dst;
 
@@ -2289,7 +2289,7 @@ fbCompositeSrc_8888RevNPx8888mmx (pixman_implementation_t *imp,
 
                *(__m64 *)dst = pack8888 (d0, d1);
            }
-           else if (a0 | a1)
+           else if (s0 | s1)
            {
                __m64 vdest = *(__m64 *)dst;
 
@@ -3064,6 +3064,7 @@ static const FastPathInfo mmx_fast_paths[] =
     { PIXMAN_OP_OVER, PIXMAN_solid,    PIXMAN_null,     PIXMAN_r5g6b5,   fbCompositeSolid_nx0565mmx,      0 },
     { PIXMAN_OP_OVER, PIXMAN_x8r8g8b8, PIXMAN_null,     PIXMAN_x8r8g8b8, fbCompositeCopyAreammx,          0 },
     { PIXMAN_OP_OVER, PIXMAN_x8b8g8r8, PIXMAN_null,     PIXMAN_x8b8g8r8, fbCompositeCopyAreammx,          0 },
+
     { PIXMAN_OP_OVER, PIXMAN_a8r8g8b8, PIXMAN_null,     PIXMAN_a8r8g8b8, fbCompositeSrc_8888x8888mmx,     0 },
     { PIXMAN_OP_OVER, PIXMAN_a8r8g8b8, PIXMAN_null,    PIXMAN_x8r8g8b8, fbCompositeSrc_8888x8888mmx,      0 },
     { PIXMAN_OP_OVER, PIXMAN_a8r8g8b8, PIXMAN_null,    PIXMAN_r5g6b5,   fbCompositeSrc_8888x0565mmx,      0 },