From 9d774969fcf8539aa301b20d659710407b7b4e83 Mon Sep 17 00:00:00 2001
From: John Emmas <johne53@tiscali.co.uk>
Date: Thu, 18 Jul 2013 12:08:34 +0100
Subject: Adapt libs/pbd/ffs.cc to be buildable with MSVC

---
 libs/pbd/ffs.cc | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

(limited to 'libs')

diff --git a/libs/pbd/ffs.cc b/libs/pbd/ffs.cc
index 0a61969e8a..557504f14e 100644
--- a/libs/pbd/ffs.cc
+++ b/libs/pbd/ffs.cc
@@ -19,14 +19,28 @@
 
 #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);
 #endif
-- 
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