HeapRing.h

00001 #ifndef _HEAPRING_H
00002 #define _HEAPRING_H
00003 
00004 template<class kind> class HeapRing {
00005 
00006     // smoothie-specific friend classes
00007     friend class Planner;
00008     friend class Conveyor;
00009     friend class Block;
00010 
00011 public:
00012     HeapRing();
00013     HeapRing(unsigned int length);
00014 
00015     ~HeapRing();
00016 
00017     /*
00018      * direct accessors
00019      */
00020     kind& head();
00021     kind& tail();
00022 
00023     void push_front(kind&) __attribute__ ((warning("Not thread-safe if pop_back() is used in ISR context!"))); // instead, prepare(head_ref()); produce_head();
00024     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();
00025 
00026     /*
00027      * pointer accessors
00028      */
00029     kind* head_ref();
00030     kind* tail_ref();
00031 
00032     void  produce_head(void);
00033     void  consume_tail(void);
00034 
00035     /*
00036      * queue status
00037      */
00038     bool is_empty(void);
00039     bool is_full(void);
00040 
00041     /*
00042      * resize
00043      *
00044      * returns true on success, or false if queue is not empty or not enough memory available
00045      */
00046     bool resize(unsigned int);
00047 
00048     /*
00049      * provide
00050      * kind*      - new buffer pointer
00051      * int length - number of items in buffer (NOT size in bytes!)
00052      *
00053      * cause HeapRing to use a specific memory location instead of allocating its own
00054      *
00055      * returns true on success, or false if queue is not empty
00056      */
00057     bool provide(kind*, unsigned int length);
00058 
00059 protected:
00060     /*
00061      * these functions are protected as they should only be used internally
00062      * or in extremely specific circumstances
00063      */
00064     kind& item(unsigned int);
00065     kind* item_ref(unsigned int);
00066 
00067     unsigned int next(unsigned int);
00068     unsigned int prev(unsigned int);
00069 
00070     /*
00071      * buffer variables
00072      */
00073     unsigned int length;
00074 
00075     volatile unsigned int head_i;
00076     volatile unsigned int tail_i;
00077 
00078 private:
00079     kind* ring;
00080 };
00081 
00082 #endif /* _HEAPRING_H */