/*
* prio_heap.h
*
- * Static-sized priority heap containing pointers. Based on CLRS,
- * chapter 6.
+ * Priority heap containing pointers. Based on CLRS, chapter 6.
*
* Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* all copies or substantial portions of the Software.
*/
-/*
- * TODO:
- * implement struct ptr_head, heap_init, heap_free, heap_insert.
- */
+#include <linux/gfp.h>
+
+struct ptr_heap {
+ size_t len, alloc_len;
+ void **ptrs;
+ int (*gt)(void *a, void *b);
+ gfp_t gfpmask;
+};
/**
* heap_maximum - return the largest element in the heap
*/
static inline void *heap_maximum(const struct ptr_heap *heap)
{
- return heap->size ? heap->ptrs[0] : NULL;
+ return heap->len ? heap->ptrs[0] : NULL;
}
+/**
+ * heap_init - initialize the heap
+ * @heap: the heap to initialize
+ * @alloc_len: number of elements initially allocated
+ * @gfp: allocation flags
+ * @gt: function to compare the elements
+ *
+ * Returns -ENOMEM if out of memory.
+ */
+extern int heap_init(struct ptr_heap *heap,
+ size_t alloc_len, gfp_t gfpmask,
+ int gt(void *a, void *b));
+
+/**
+ * heap_free - free the heap
+ * @heap: the heap to free
+ */
+extern void heap_free(struct ptr_heap *heap);
+
+/**
+ * heap_insert - insert an element into the heap
+ * @heap: the heap to be operated on
+ * @p: the element to add
+ *
+ * Insert an element into the heap.
+ *
+ * Returns -ENOMEM if out of memory.
+ */
+extern int heap_insert(struct ptr_heap *heap, void *p);
/**
* heap_remove - remove the largest element from the heap
* the heap is empty.
*
* This is the equivalent of calling heap_remove() and then heap_insert(), but
- * it only rebalances the heap once.
+ * it only rebalances the heap once. It never allocates memory.
*/
extern void *heap_replace_max(struct ptr_heap *heap, void *p);