icd: add u_ffs()
diff --git a/icd/common/icd-utils.h b/icd/common/icd-utils.h
index fdefd16..76d8fa9 100644
--- a/icd/common/icd-utils.h
+++ b/icd/common/icd-utils.h
@@ -31,6 +31,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <assert.h>
+#include <strings.h> /* for ffs() */
 #include "icd.h"
 
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
@@ -53,6 +54,11 @@
     return ((val & (val - 1)) == 0);
 }
 
+static inline int u_ffs(int val)
+{
+    return ffs(val);
+}
+
 static inline unsigned int u_align(unsigned int val, unsigned alignment)
 {
     assert(alignment && u_is_pow2(alignment));