X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fpbd%2Fffs.cc;h=1ca913c54c3234710fda0cd0e9b396142c760c43;hb=5b40e073e9c973479c3d286a007c57e1e0fa3d0f;hp=8f7ecdb502413af98420c654496019f992458c4f;hpb=650964f3203319b013c49a286b5fc5fc203f3bbb;p=ardour.git

diff --git a/libs/pbd/ffs.cc b/libs/pbd/ffs.cc
index 8f7ecdb502..1ca913c54c 100644
--- 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
 }