Binary heap fix & improvement.

Fixed a bug when removing last element of binary heap (its parent would
be removed instead if it had the same value).
Binary heap now allows custom swapper function/macro. Added `swap_ptr`
macro to swap two pointers in place (`swap` is not suitable for
pointers). This allows to store pointers in binary heap.

3 files changed, 18 insertions, 11 deletions

diff --git a/src/common/cbasetypes.h b/src/common/cbasetypes.h
index bfe8bf8f8..82ca9df69 100644
--- a/src/common/cbasetypes.h
+++ b/src/common/cbasetypes.h
@@ -300,6 +300,8 @@ typedef char bool;
 #endif
 #endif
 
+#define swap_ptr(a,b) if ((a) != (b)) ((a) = (void*)((intptr_t)(a) ^ (intptr_t)(b)), (b) = (void*)((intptr_t)(a) ^ (intptr_t)(b)), (a) = (void*)((intptr_t)(a) ^ (intptr_t)(b)))
+
 #ifndef max
 #define max(a,b) (((a) > (b)) ? (a) : (b))
 #endif
diff --git a/src/common/db.h b/src/common/db.h
index 5a555b2fa..aa4bfb054 100644
--- a/src/common/db.h
+++ b/src/common/db.h
@@ -1392,7 +1392,8 @@ void  linkdb_foreach( struct linkdb_node** head, LinkDBFunc func, ...  );
 /// @param __heap Binary heap
 /// @param __val Value
 /// @param __topcmp Comparator
-#define BHEAP_PUSH(__heap,__val,__topcmp) \
+/// @param __swp Swapper
+#define BHEAP_PUSH(__heap,__val,__topcmp,__swp) \
 	do{ \
 		size_t _i_ = VECTOR_LENGTH(__heap); \
 		VECTOR_PUSH(__heap,__val); /* insert at end */ \
@@ -1401,7 +1402,7 @@ void  linkdb_foreach( struct linkdb_node** head, LinkDBFunc func, ...  );
 			size_t _parent_ = (_i_-1)/2; \
 			if( __topcmp(VECTOR_INDEX(__heap,_parent_),VECTOR_INDEX(__heap,_i_)) < 0 ) \
 				break; /* done */ \
-			swap(VECTOR_INDEX(__heap,_parent_),VECTOR_INDEX(__heap,_i_)); \
+			__swp(VECTOR_INDEX(__heap,_parent_),VECTOR_INDEX(__heap,_i_)); \
 			_i_ = _parent_; \
 		} \
 	}while(0)
@@ -1418,7 +1419,8 @@ void  linkdb_foreach( struct linkdb_node** head, LinkDBFunc func, ...  );
 ///
 /// @param __heap Binary heap
 /// @param __topcmp Comparator
-#define BHEAP_POP(__heap,__topcmp) BHEAP_POPINDEX(__heap,0,__topcmp)
+/// @param __swp Swapper
+#define BHEAP_POP(__heap,__topcmp,__swp) BHEAP_POPINDEX(__heap,0,__topcmp,__swp)
 
 
 
@@ -1433,16 +1435,19 @@ void  linkdb_foreach( struct linkdb_node** head, LinkDBFunc func, ...  );
 /// @param __heap Binary heap
 /// @param __idx Index
 /// @param __topcmp Comparator
-#define BHEAP_POPINDEX(__heap,__idx,__topcmp) \
+/// @param __swp Swapper
+#define BHEAP_POPINDEX(__heap,__idx,__topcmp,__swp) \
 	do{ \
 		size_t _i_ = __idx; \
 		VECTOR_INDEX(__heap,__idx) = VECTOR_POP(__heap); /* put last at index */ \
+		if( _i_ >= VECTOR_LENGTH(__heap)) /* removed last, nothing to do */ \
+			break; \
 		while( _i_ ) \
 		{ /* restore heap property in parents */ \
 			size_t _parent_ = (_i_-1)/2; \
 			if( __topcmp(VECTOR_INDEX(__heap,_parent_),VECTOR_INDEX(__heap,_i_)) < 0 ) \
 				break; /* done */ \
-			swap(VECTOR_INDEX(__heap,_parent_),VECTOR_INDEX(__heap,_i_)); \
+			__swp(VECTOR_INDEX(__heap,_parent_),VECTOR_INDEX(__heap,_i_)); \
 			_i_ = _parent_; \
 		} \
 		while( _i_ < VECTOR_LENGTH(__heap) ) \
@@ -1454,12 +1459,12 @@ void  linkdb_foreach( struct linkdb_node** head, LinkDBFunc func, ...  );
 				break; /* done */ \
 			else if( _rchild_ >= VECTOR_LENGTH(__heap) || __topcmp(VECTOR_INDEX(__heap,_lchild_),VECTOR_INDEX(__heap,_rchild_)) <= 0 ) \
 			{ /* left child */ \
-				swap(VECTOR_INDEX(__heap,_i_),VECTOR_INDEX(__heap,_lchild_)); \
+				__swp(VECTOR_INDEX(__heap,_i_),VECTOR_INDEX(__heap,_lchild_)); \
 				_i_ = _lchild_; \
 			} \
 			else \
 			{ /* right child */ \
-				swap(VECTOR_INDEX(__heap,_i_),VECTOR_INDEX(__heap,_rchild_)); \
+				__swp(VECTOR_INDEX(__heap,_i_),VECTOR_INDEX(__heap,_rchild_)); \
 				_i_ = _rchild_; \
 			} \
 		} \
diff --git a/src/common/timer.c b/src/common/timer.c
index 955a971c8..f019c6927 100644
--- a/src/common/timer.c
+++ b/src/common/timer.c
@@ -195,7 +195,7 @@ unsigned int timer_gettick(void) {
 /// Adds a timer to the timer_heap
 static void push_timer_heap(int tid) {
 	BHEAP_ENSURE(timer_heap, 1, 256);
-	BHEAP_PUSH(timer_heap, tid, DIFFTICK_MINTOPCMP);
+	BHEAP_PUSH(timer_heap, tid, DIFFTICK_MINTOPCMP, swap);
 }
 
 /*==========================
@@ -322,9 +322,9 @@ int timer_settick(int tid, unsigned int tick) {
 		return (int)tick;// nothing to do, already in propper position
 
 	// pop and push adjusted timer
-	BHEAP_POPINDEX(timer_heap, i, DIFFTICK_MINTOPCMP);
+	BHEAP_POPINDEX(timer_heap, i, DIFFTICK_MINTOPCMP, swap);
 	timer_data[tid].tick = tick;
-	BHEAP_PUSH(timer_heap, tid, DIFFTICK_MINTOPCMP);
+	BHEAP_PUSH(timer_heap, tid, DIFFTICK_MINTOPCMP, swap);
 	return (int)tick;
 }
 
@@ -342,7 +342,7 @@ int do_timer(unsigned int tick) {
 			break; // no more expired timers to process
 
 		// remove timer
-		BHEAP_POP(timer_heap, DIFFTICK_MINTOPCMP);
+		BHEAP_POP(timer_heap, DIFFTICK_MINTOPCMP, swap);
 		timer_data[tid].type |= TIMER_REMOVE_HEAP;
 
 		if( timer_data[tid].func ) {