commit 6c10328eb88b0641586f31a782b63f45eada5609
author Arkady Shapkin <arkady.shapkin@gmail.com> Thu Feb 15 23:17:46 2018 +0300
committer Behdad Esfahbod <behdad@behdad.org> Thu Feb 15 14:31:25 2018 -0800
tree 73bef574145a56bef58ff0f29c2e1c307a2207d2
parent 23d21a74b55eaf6d6d367097099e6b3bb78bae37

Use _BitScanForward and _BitScanReverse on MSVC

src/hb-private.hh

diff --git a/src/hb-private.hh b/src/hb-private.hh
index 6430ba8..22948ae 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -51,6 +51,9 @@
 #include <stdio.h>
 #include <stdarg.h>
 
+#if defined(_MSC_VER)
+#include <intrin.h>
+#endif
 
 #define HB_PASTE1(a,b) a##b
 #define HB_PASTE(a,b) HB_PASTE1(a,b)
@@ -352,6 +355,10 @@
 {
 #if defined(__GNUC__) && (__GNUC__ >= 4) && defined(__OPTIMIZE__)
   return likely (number) ? (sizeof (unsigned int) * 8 - __builtin_clz (number)) : 0;
+#elif defined_MSC_VER) && defined(__OPTIMIZE__)
+  unsigned long where;
+  if (_BitScanReverse(&where, number)) return 1 + where;
+  return 0;
 #else
   unsigned int n_bits = 0;
   while (number) {
@@ -368,6 +375,11 @@
 {
 #if defined(__GNUC__) && (__GNUC__ >= 4) && defined(__OPTIMIZE__)
   return likely (number) ? __builtin_ctz (number) : 0;
+#elif defined_MSC_VER) && defined(__OPTIMIZE__)
+  unsigned long where;
+  if (_BitScanForward(&where, n)) return where;
+  return 0;
+}
 #else
   unsigned int n_bits = 0;
   if (unlikely (!number)) return 0;