Math Utils: Add bitscan 64bit version

2 files changed, 26 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_math_bits.h b/source/blender/blenlib/BLI_math_bits.h
index b602900bedc..b007dd7cfed 100644
--- a/source/blender/blenlib/BLI_math_bits.h
+++ b/source/blender/blenlib/BLI_math_bits.h
@@ -31,6 +31,7 @@ extern "C" {
 /* 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);
+MINLINE unsigned int bitscan_forward_uint64(unsigned long long a);
 
 /* Similar to above, but also clears the bit. */
 MINLINE int bitscan_forward_clear_i(int *a);
@@ -39,6 +40,7 @@ MINLINE unsigned int bitscan_forward_clear_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);
+MINLINE unsigned int bitscan_reverse_uint64(unsigned long long a);
 
 /* Similar to above, but also clears the bit. */
 MINLINE int bitscan_reverse_clear_i(int *a);
diff --git a/source/blender/blenlib/intern/math_bits_inline.c b/source/blender/blenlib/intern/math_bits_inline.c
index e7a7b17e1e4..3a0cea182ba 100644
--- a/source/blender/blenlib/intern/math_bits_inline.c
+++ b/source/blender/blenlib/intern/math_bits_inline.c
@@ -40,6 +40,18 @@ MINLINE unsigned int bitscan_forward_uint(unsigned int a)
 #endif
 }
 
+MINLINE unsigned int bitscan_forward_uint64(unsigned long long a)
+{
+  BLI_assert(a != 0);
+#ifdef _MSC_VER
+  unsigned long ctz;
+  _BitScanForward64(&ctz, a);
+  return ctz;
+#else
+  return (unsigned int)__builtin_ctz(a);
+#endif
+}
+
 MINLINE int bitscan_forward_i(int a)
 {
   return (int)bitscan_forward_uint((unsigned int)a);
@@ -69,6 +81,18 @@ MINLINE unsigned int bitscan_reverse_uint(unsigned int a)
 #endif
 }
 
+MINLINE unsigned int bitscan_reverse_uint64(unsigned long long a)
+{
+  BLI_assert(a != 0);
+#ifdef _MSC_VER
+  unsigned long clz;
+  _BitScanReverse64(&clz, a);
+  return 31 - clz;
+#else
+  return (unsigned int)__builtin_clzll(a);
+#endif
+}
+
 MINLINE int bitscan_reverse_i(int a)
 {
   return (int)bitscan_reverse_uint((unsigned int)a);