fifo.h

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#ifndef FIFO_H
#define FIFO_H
//#include "core_cm0.h"

extern volatile int gblMutex;

static inline void fifo_lock (void) {
  asm volatile ("cpsid i");
  gblMutex++;
}
static inline void fifo_unlock (void) {
  if (--gblMutex) return;
  asm volatile ("cpsie i");
}

//#define FIFODEPTH (1<<10)
//#define FIFOMASK  (FIFODEPTH-1)
template <class T> class Fifo {
  public:   // veřejné metody
    Fifo (const unsigned depth) : max (depth) {
      buf = new T [depth];
      rdi = 0; wri = 0; len = 0;
    };
    bool Write (const T& c) {
      if (len < max) { buf [wri++] = c; saturate (wri); safeInc(); return true; }
      else return false;
    };
    bool Read  (T& c) {
      if (len > 0) { c = buf [rdi++];   saturate (rdi); safeDec(); return true; }
      else return false;
    };
  protected:  // chráněné metody
    void saturate (volatile int& index) {
      //index &= FIFOMASK;  // FIFODEPTH je rovno 2 ** n, kde n je celé číslo. 
      if (index < max) return; index = 0; // FIFODEPTH obecně int
    };
    void safeInc (void) { fifo_lock(); len++; fifo_unlock(); };
    void safeDec (void) { fifo_lock(); len--; fifo_unlock(); };
  private:    // privátní data
    const int    max;
    T     *      buf;             
    volatile int rdi, wri, len;   
};

#endif // FIFO_H