From 14e94647bf09d9841cfa0ac650aa37ffc1e3862c Mon Sep 17 00:00:00 2001
From: Neil Roberts <neil@linux.intel.com>
Date: Fri, 17 Dec 2010 16:06:10 +0000
Subject: [PATCH] cogl-util: Add an internal wrapper for the ffs function

The ffs function is defined in C99 so if we want to use it in Cogl we
need to provide a fallback for MSVC. This adds a configure check for
the function and then a fallback using a while loop if it is not
available.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2491
---
 cogl/cogl-util.c | 21 +++++++++++++++++++++
 cogl/cogl-util.h |  8 ++++++++
 2 files changed, 29 insertions(+)

diff --git a/cogl/cogl-util.c b/cogl/cogl-util.c
index 29165872b..d38049a93 100644
--- a/cogl/cogl-util.c
+++ b/cogl/cogl-util.c
@@ -218,3 +218,24 @@ _cogl_util_one_at_a_time_mix (unsigned int hash)
   return hash;
 }
 
+/* The 'ffs' function is part of C99 so it isn't always available */
+#ifndef HAVE_FFS
+
+int
+_cogl_util_ffs (int num)
+{
+  int i = 1;
+
+  if (num == 0)
+    return 0;
+
+  while ((num & 1) == 0)
+    {
+      num >>= 1;
+      i++;
+    }
+
+  return i;
+}
+
+#endif /* HAVE_FFS */
diff --git a/cogl/cogl-util.h b/cogl/cogl-util.h
index 0ac56c9d9..e32fcd68e 100644
--- a/cogl/cogl-util.h
+++ b/cogl/cogl-util.h
@@ -95,4 +95,12 @@ _cogl_util_one_at_a_time_hash (unsigned int hash,
 unsigned int
 _cogl_util_one_at_a_time_mix (unsigned int hash);
 
+/* The 'ffs' function is part of C99 so it isn't always available */
+#ifdef HAVE_FFS
+#define _cogl_util_ffs ffs
+#else
+int
+_cogl_util_ffs (int num);
+#endif
+
 #endif /* __COGL_UTIL_H */