From af591f5c09e0e2a1ce91d94d1d0a08cfb5a54c6b Mon Sep 17 00:00:00 2001
From: Neil Roberts <neil@linux.intel.com>
Date: Thu, 20 May 2010 12:37:56 +0100
Subject: [PATCH] cogl-texture-2d: Optimise _cogl_texture_2d_is_pot
This takes the simple algorithm from here:
http://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2
This avoids a loop and is much faster.
---
cogl/cogl-texture-2d.c | 15 +--------------
1 file changed, 1 insertion(+), 14 deletions(-)
diff --git a/cogl/cogl-texture-2d.c b/cogl/cogl-texture-2d.c
index 044f75d33..4ec2e0ec9 100644
--- a/cogl/cogl-texture-2d.c
+++ b/cogl/cogl-texture-2d.c
@@ -156,21 +156,8 @@ _cogl_texture_2d_free (CoglTexture2D *tex_2d)
static gboolean
_cogl_texture_2d_is_pot (unsigned int num)
{
- gboolean have_bit = FALSE;
-
/* Make sure there is only one bit set */
- while (num)
- {
- if (num & 1)
- {
- if (have_bit)
- return FALSE;
- have_bit = TRUE;
- }
- num >>= 1;
- }
-
- return TRUE;
+ return (num & (num - 1)) == 0;
}
static gboolean