Diff: libs/HeapRing.h

Revision:

2:1df0b61d3b5a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libs/HeapRing.h	Fri Feb 28 18:52:52 2014 -0800
@@ -0,0 +1,82 @@
+#ifndef _HEAPRING_H
+#define _HEAPRING_H
+
+template<class kind> class HeapRing {
+
+    // smoothie-specific friend classes
+    friend class Planner;
+    friend class Conveyor;
+    friend class Block;
+
+public:
+    HeapRing();
+    HeapRing(unsigned int length);
+
+    ~HeapRing();
+
+    /*
+     * direct accessors
+     */
+    kind& head();
+    kind& tail();
+
+    void push_front(kind&) __attribute__ ((warning("Not thread-safe if pop_back() is used in ISR context!"))); // instead, prepare(head_ref()); produce_head();
+    kind& pop_back(void) __attribute__ ((warning("Not thread-safe if head_ref() is used to prepare new items, or push_front() is used in ISR context!"))); // instead, consume(tail_ref()); consume_tail();
+
+    /*
+     * pointer accessors
+     */
+    kind* head_ref();
+    kind* tail_ref();
+
+    void  produce_head(void);
+    void  consume_tail(void);
+
+    /*
+     * queue status
+     */
+    bool is_empty(void);
+    bool is_full(void);
+
+    /*
+     * resize
+     *
+     * returns true on success, or false if queue is not empty or not enough memory available
+     */
+    bool resize(unsigned int);
+
+    /*
+     * provide
+     * kind*      - new buffer pointer
+     * int length - number of items in buffer (NOT size in bytes!)
+     *
+     * cause HeapRing to use a specific memory location instead of allocating its own
+     *
+     * returns true on success, or false if queue is not empty
+     */
+    bool provide(kind*, unsigned int length);
+
+protected:
+    /*
+     * these functions are protected as they should only be used internally
+     * or in extremely specific circumstances
+     */
+    kind& item(unsigned int);
+    kind* item_ref(unsigned int);
+
+    unsigned int next(unsigned int);
+    unsigned int prev(unsigned int);
+
+    /*
+     * buffer variables
+     */
+    unsigned int length;
+
+    volatile unsigned int head_i;
+    volatile unsigned int tail_i;
+
+private:
+    kind* ring;
+};
+
+#endif /* _HEAPRING_H */