[Bf-blender-cvs] [de9e5a09265] master: Math utils: Go away form naive code for highest_order_bit_uint

[Sergey Sharybin]

Commit: de9e5a092659cf2424b55dca4ac6f149966fe427
Author: Sergey Sharybin
Date:   Fri Dec 15 16:28:53 2017 +0100
Branches: master
https://developer.blender.org/rBde9e5a092659cf2424b55dca4ac6f149966fe427

Math utils: Go away form naive code for highest_order_bit_uint

===================================================================

M	source/blender/blenlib/intern/math_bits_inline.c

===================================================================

diff --git a/source/blender/blenlib/intern/math_bits_inline.c b/source/blender/blenlib/intern/math_bits_inline.c
index fdef0f9c9c6..e967ecbb3a3 100644
--- a/source/blender/blenlib/intern/math_bits_inline.c
+++ b/source/blender/blenlib/intern/math_bits_inline.c
@@ -63,12 +63,10 @@ MINLINE unsigned int bitscan_reverse_uint(unsigned int a)
 
 MINLINE unsigned int highest_order_bit_uint(unsigned int n)
 {
-	n |= (n >>  1);
-	n |= (n >>  2);
-	n |= (n >>  4);
-	n |= (n >>  8);
-	n |= (n >> 16);
-	return n - (n >> 1);
+	if (n == 0) {
+		return 0;
+	}
+	return 1 << (sizeof(unsigned int) * 8 - bitscan_reverse_uint(n));
 }
 
 MINLINE unsigned short highest_order_bit_s(unsigned short n)