[src/trunk]: src/sys/dev/rasops skip the multiplications for alpha values of ...

[macallan <macallan%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/756026a1f583
branches:  trunk
changeset: 772268:756026a1f583
user:      macallan <macallan%NetBSD.org@localhost>
date:      Tue Dec 27 06:24:40 2011 +0000

description:
skip the multiplications for alpha values of 0 and 255, just use background
and foreground colours there

diffstat:

 sys/dev/rasops/rasops32.c |  25 +++++++++++++++++--------
 1 files changed, 17 insertions(+), 8 deletions(-)

diffs (46 lines):

diff -r c0595c707eeb -r 756026a1f583 sys/dev/rasops/rasops32.c
--- a/sys/dev/rasops/rasops32.c Tue Dec 27 01:24:27 2011 +0000
+++ b/sys/dev/rasops/rasops32.c Tue Dec 27 06:24:40 2011 +0000
@@ -1,4 +1,4 @@
-/*      $NetBSD: rasops32.c,v 1.21 2011/12/24 02:13:21 macallan Exp $  */
+/*      $NetBSD: rasops32.c,v 1.22 2011/12/27 06:24:40 macallan Exp $  */
 
 /*-
  * Copyright (c) 1999 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: rasops32.c,v 1.21 2011/12/24 02:13:21 macallan Exp $");
+__KERNEL_RCSID(0, "$NetBSD: rasops32.c,v 1.22 2011/12/27 06:24:40 macallan Exp $");
 
 #include "opt_rasops.h"
 
@@ -158,12 +158,21 @@
                                dp = rp + ri->ri_width * y;
                                for (x = 0; x < width; x++) {
                                        aval = *fr;
-                                       r = aval * r1 + (255 - aval) * r0;
-                                       g = aval * g1 + (255 - aval) * g0;
-                                       b = aval * b1 + (255 - aval) * b0;
-                                       *dp = (r & 0xff00) << 8 | 
-                                             (g & 0xff00) | 
-                                             (b & 0xff00) >> 8;
+                                       if (aval == 0) {
+                                               *dp = clr[0];
+                                       } else if (aval == 255) {
+                                               *dp = clr[1];
+                                       } else {
+                                               r = aval * r1 +
+                                                   (255 - aval) * r0;
+                                               g = aval * g1 +
+                                                   (255 - aval) * g0;
+                                               b = aval * b1 +
+                                                   (255 - aval) * b0;
+                                               *dp = (r & 0xff00) << 8 | 
+                                                     (g & 0xff00) | 
+                                                     (b & 0xff00) >> 8;
+                                       }
                                        dp++;
                                        fr++;
                                }