1 files changed, 68 insertions, 7 deletions
diff --git a/source/blender/blenlib/intern/math_bits_inline.c b/source/blender/blenlib/intern/math_bits_inline.c
index 82d7e2114c2..9b16756134e 100644
--- a/source/blender/blenlib/intern/math_bits_inline.c
+++ b/source/blender/blenlib/intern/math_bits_inline.c
@@ -25,16 +25,77 @@
 #ifndef __MATH_BITS_INLINE_C__
 #define __MATH_BITS_INLINE_C__
 
+#ifdef _MSC_VER
+#  include <intrin.h>
+#endif
+
 #include "BLI_math_bits.h"
 
-MINLINE unsigned int highest_order_bit_i(unsigned int n)
+MINLINE int bitscan_forward_i(int a)
 {
-	n |= (n >>  1);
-	n |= (n >>  2);
-	n |= (n >>  4);
-	n |= (n >>  8);
-	n |= (n >> 16);
-	return n - (n >> 1);
+	BLI_assert(a != 0);
+#ifdef _MSC_VER
+	unsigned long ctz;
+	_BitScanForward(&ctz, a);
+	return ctz;
+#else
+	return __builtin_ctz((unsigned int)a);
+#endif
+}
+
+MINLINE unsigned int bitscan_forward_uint(unsigned int a)
+{
+	return (unsigned int)bitscan_forward_i((int)a);
+}
+
+MINLINE int bitscan_forward_clear_i(int *a)
+{
+	int i = bitscan_forward_i(*a);
+	*a &= (*a) - 1;
+	return i;
+}
+
+MINLINE unsigned int bitscan_forward_clear_uint(unsigned int *a)
+{
+	return (unsigned int)bitscan_forward_clear_i((int *)a);
+}
+
+MINLINE int bitscan_reverse_i(int a)
+{
+	BLI_assert(a != 0);
+#ifdef _MSC_VER
+	unsigned long clz;
+	_BitScanReverse(&clz, a);
+	return clz;
+#else
+	return __builtin_clz((unsigned int)a);
+#endif
+}
+
+MINLINE unsigned int bitscan_reverse_uint(unsigned int a)
+{
+	return (unsigned int)bitscan_reverse_i((int)a);
+}
+
+MINLINE int bitscan_reverse_clear_i(int *a)
+{
+	int i = bitscan_reverse_i(*a);
+	/* TODO(sergey): This could probably be optimized. */
+	*a &= ~(1 << (sizeof(int) * 8 - i - 1));
+	return i;
+}
+
+MINLINE unsigned int bitscan_reverse_clear_uint(unsigned int *a)
+{
+	return (unsigned int)bitscan_reverse_clear_i((int *)a);
+}
+
+MINLINE unsigned int highest_order_bit_uint(unsigned int n)
+{
+	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)