-AVInteger av_add_i(AVInteger a, AVInteger b);
-AVInteger av_sub_i(AVInteger a, AVInteger b);
-int av_log2_i(AVInteger a);
-AVInteger av_mul_i(AVInteger a, AVInteger b);
-int av_cmp_i(AVInteger a, AVInteger b);
-AVInteger av_shr_i(AVInteger a, int s);
+AVInteger av_add_i(AVInteger a, AVInteger b) av_const;
+AVInteger av_sub_i(AVInteger a, AVInteger b) av_const;
+
+/**
+ * Return the rounded-down value of the base 2 logarithm of the given
+ * AVInteger. This is simply the index of the most significant bit
+ * which is 1, or 0 if all bits are 0.
+ */
+int av_log2_i(AVInteger a) av_const;
+AVInteger av_mul_i(AVInteger a, AVInteger b) av_const;
+
+/**
+ * Return 0 if a==b, 1 if a>b and -1 if a<b.
+ */
+int av_cmp_i(AVInteger a, AVInteger b) av_const;
+
+/**
+ * bitwise shift
+ * @param s the number of bits by which the value should be shifted right,
+ may be negative for shifting left
+ */
+AVInteger av_shr_i(AVInteger a, int s) av_const;
+
+/**
+ * Return a % b.
+ * @param quot a/b will be stored here.
+ */