MINOR: standard: Add my_ffsl function to get the position of the bit set to one

diff --git a/include/common/standard.h b/include/common/standard.h
index b2d67edc516a22804b4b01eaae9bdff8dfd7041f..dd89203ae8e96f0eed7befac6dfe33a02b09f0c6 100644 (file)
--- a/include/common/standard.h
+++ b/include/common/standard.h
@@ -793,6 +793,46 @@ static inline unsigned int my_popcountl(unsigned long a)
        return cnt;
 }
 
+/* Simple ffs implementation. It returns the position of the lowest bit set to
+ * one. */
+static inline unsigned int my_ffsl(unsigned long a)
+{
+       unsigned int cnt;
+
+       if (!a)
+               return 0;
+
+       cnt = 1;
+#if LONG_MAX > 0x7FFFFFFFL /* 64bits */
+       if (!(a & 0xFFFFFFFFUL)) {
+               a >>= 32;
+               cnt += 32;
+       }
+#endif
+       if (!(a & 0XFFFFU)) {
+               a >>= 16;
+               cnt += 16;
+       }
+       if (!(a & 0XFF)) {
+               a >>= 8;
+               cnt += 8;
+       }
+       if (!(a & 0xf)) {
+               a >>= 4;
+               cnt += 4;
+       }
+       if (!(a & 0x3)) {
+               a >>= 2;
+               cnt += 2;
+       }
+       if (!(a & 0x1)) {
+               a >>= 1;
+               cnt += 1;
+       }
+
+       return cnt;
+}
+
 /* Build a word with the <bits> lower bits set (reverse of my_popcountl) */
 static inline unsigned long nbits(int bits)
 {