Add comments to compare/swap function

include/ucore/heapsort.h

@@ -7,10 +7,10 @@
 extern "C" {
 #endif
 ///compare function. Needs only to return < 0 if 
-//the first element is less than the second
-typedef int (*uc_hs_cmp)(const void *, const void *, void *cookie);
-//swap function
-typedef void (*uc_hs_swp)(void *, void *);
+//a is less tan b
+typedef int (*uc_hs_cmp)(const void *a, const void *b, void *cookie);
+//swap function, must swap around element a and b
+typedef void (*uc_hs_swp)(void *a, void *b);
 
 /** Sort an array.
  * @param base start of array