From 64a23a0f9c6a08f6118f6488c191a079c43245a2 Mon Sep 17 00:00:00 2001
From: Brian Paul <brian.paul@tungstengraphics.com>
Date: Thu, 14 Sep 2000 23:13:51 +0000
Subject: updated comments

---
 src/mesa/main/dd.h    | 9 ++++++---
 src/mesa/main/image.c | 9 +++++++--
 2 files changed, 13 insertions(+), 5 deletions(-)

(limited to 'src')

diff --git a/src/mesa/main/dd.h b/src/mesa/main/dd.h
index 68982004a2..0341c50acc 100644
--- a/src/mesa/main/dd.h
+++ b/src/mesa/main/dd.h
@@ -1,4 +1,4 @@
-/* $Id: dd.h,v 1.31 2000/09/08 21:44:55 brianp Exp $ */
+/* $Id: dd.h,v 1.32 2000/09/14 23:13:51 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -856,8 +856,11 @@ struct dd_function_table {
 
    void (*RegisterVB)( struct vertex_buffer *VB );
    void (*UnregisterVB)( struct vertex_buffer *VB );
-   /* Do any processing (eg allocate memory) required to set up a new
-    * vertex_buffer.  
+   /* When Mesa creates a new vertex buffer it calls Driver.RegisterVB()
+    * so the device driver can allocate its own vertex buffer data and
+    * hook it to the VB->driver_data pointer.
+    * When Mesa destroys a vertex buffer it calls Driver.UnegisterVB()
+    * so the driver can deallocate its own data attached to VB->driver_data.
     */
 
 
diff --git a/src/mesa/main/image.c b/src/mesa/main/image.c
index 4b08c065c4..2d4f3014e2 100644
--- a/src/mesa/main/image.c
+++ b/src/mesa/main/image.c
@@ -1,4 +1,4 @@
-/* $Id: image.c,v 1.40 2000/09/12 21:10:25 brianp Exp $ */
+/* $Id: image.c,v 1.41 2000/09/14 23:13:51 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -63,6 +63,11 @@ const struct gl_pixelstore_attrib _mesa_native_packing = {
 
 /*
  * Flip the 8 bits in each byte of the given array.
+ *
+ * XXX try this trick to flip bytes someday:
+ *  v = ((v & 0x55555555) << 1) | ((v >> 1) & 0x55555555);
+ *  v = ((v & 0x33333333) << 2) | ((v >> 2) & 0x33333333);
+ *  v = ((v & 0x0f0f0f0f) << 4) | ((v >> 4) & 0x0f0f0f0f);
  */
 static void
 flip_bytes( GLubyte *p, GLuint n )
@@ -70,7 +75,7 @@ flip_bytes( GLubyte *p, GLuint n )
    register GLuint i, a, b;
 
    for (i=0;i<n;i++) {
-      b = (GLuint) p[i];
+      b = (GLuint) p[i];        /* words are often faster than bytes */
       a = ((b & 0x01) << 7) |
 	  ((b & 0x02) << 5) |
 	  ((b & 0x04) << 3) |
-- 
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