fix typos in d442190b

[ardour.git] / libs / pbd / ffs.cc

diff --git a/libs/pbd/ffs.cc b/libs/pbd/ffs.cc
index 8f7ecdb502413af98420c654496019f992458c4f..1ca913c54c3234710fda0cd0e9b396142c760c43 100644 (file)
--- a/libs/pbd/ffs.cc
+++ b/libs/pbd/ffs.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2013 Tim Mayberry 
+    Copyright (C) 2013 Tim Mayberry
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -19,16 +19,30 @@
 
 #include "pbd/ffs.h"
 
+#ifndef COMPILER_MSVC
 #include <strings.h>
+#endif
 
 namespace PBD {
 int
 ffs (int x)
 {
-#if defined(WIN32) && defined(__GNUC__)
+#if defined (COMPILER_MINGW)
        return __builtin_ffs(x);
+#elif defined (COMPILER_MSVC)
+       unsigned long index;
+#ifdef WIN64
+       if (0 != _BitScanForward64(&index, (__int64)x))
+#else
+       if (0 != _BitScanForward(&index, (unsigned long)x))
+#endif
+               index++;    // Make the result 1-based
+       else
+               index = 0;  // All bits were zero
+
+       return (int)index;
 #else
-       return ffs(x);
+       return ::ffs(x);
 #endif
 }