[Bf-blender-cvs] [412de222f87] master: Math utils: Add bit scan operations
Sergey Sharybin
noreply at git.blender.org
Fri Dec 15 16:59:16 CET 2017
Commit: 412de222f8711893f7ed66630b6b8a1473810ab2
Author: Sergey Sharybin
Date: Fri Dec 15 16:22:54 2017 +0100
Branches: master
https://developer.blender.org/rB412de222f8711893f7ed66630b6b8a1473810ab2
Math utils: Add bit scan operations
===================================================================
M source/blender/blenlib/BLI_math_bits.h
M source/blender/blenlib/intern/math_bits_inline.c
===================================================================
diff --git a/source/blender/blenlib/BLI_math_bits.h b/source/blender/blenlib/BLI_math_bits.h
index 40a1d84b0e1..248b615e3f8 100644
--- a/source/blender/blenlib/BLI_math_bits.h
+++ b/source/blender/blenlib/BLI_math_bits.h
@@ -31,6 +31,14 @@ extern "C" {
#include "BLI_math_inline.h"
+/* Search the value from LSB to MSB for a set bit. Returns index of this bit. */
+MINLINE int bitscan_forward_i(int a);
+MINLINE unsigned int bitscan_forward_uint(unsigned int a);
+
+/* Search the value from MSB to LSB for a set bit. Returns index of this bit. */
+MINLINE int bitscan_reverse_i(int a);
+MINLINE unsigned int bitscan_reverse_uint(unsigned int a);
+
/* NOTE: Those functions returns 2 to the power of index of highest order bit. */
MINLINE unsigned int highest_order_bit_uint(unsigned int n);
MINLINE unsigned short highest_order_bit_s(unsigned short n);
diff --git a/source/blender/blenlib/intern/math_bits_inline.c b/source/blender/blenlib/intern/math_bits_inline.c
index 9f502d367cb..fdef0f9c9c6 100644
--- a/source/blender/blenlib/intern/math_bits_inline.c
+++ b/source/blender/blenlib/intern/math_bits_inline.c
@@ -27,6 +27,40 @@
#include "BLI_math_bits.h"
+MINLINE int bitscan_forward_i(int a)
+{
+ 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_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 unsigned int highest_order_bit_uint(unsigned int n)
{
n |= (n >> 1);
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