src/apps/activitymonitor/CircularBuffer.h

   1 /*
   2  * Copyright 2008-2013, Axel Dörfler, axeld@pinc-software.de.
   3  * Distributed under the terms of the MIT License.
   4  */
   5 #ifndef CIRCULAR_BUFFER_H
   6 #define CIRCULAR_BUFFER_H
   7
   8
   9 #include <stdlib.h>
  10
  11 #include <OS.h>
  12
  13
  14 template<typename Type>
  15 class CircularBuffer {
  16 public:
  17         CircularBuffer(size_t size)
  18                 :
  19                 fSize(0),
  20                 fBuffer(NULL)
  21         {
  22                 SetSize(size);
  23         }
  24
  25         ~CircularBuffer()
  26         {
  27                 free(fBuffer);
  28         }
  29
  30         status_t InitCheck() const
  31         {
  32                 return fBuffer != NULL ? B_OK : B_NO_MEMORY;
  33         }
  34
  35         status_t SetSize(size_t size)
  36         {
  37                 MakeEmpty();
  38
  39                 if (fSize == size)
  40                         return B_OK;
  41
  42                 fSize = size;
  43                 fBuffer = (Type*)malloc(fSize * sizeof(Type));
  44                 if (fBuffer == NULL) {
  45                         fSize = 0;
  46                         return B_NO_MEMORY;
  47                 }
  48
  49                 return B_OK;
  50         }
  51
  52         void MakeEmpty()
  53         {
  54                 fIn = 0;
  55                 fFirst = 0;
  56         }
  57
  58         bool IsEmpty() const
  59         {
  60                 return fIn == 0;
  61         }
  62
  63         int32 CountItems() const
  64         {
  65                 return fIn;
  66         }
  67
  68         Type* ItemAt(int32 index) const
  69         {
  70                 if (index >= (int32)fIn || index < 0 || fBuffer == NULL)
  71                         return NULL;
  72
  73                 return &fBuffer[(fFirst + index) % fSize];
  74         }
  75
  76         void AddItem(const Type& item)
  77         {
  78                 uint32 index;
  79                 if (fIn < fSize)
  80                         index = fFirst + fIn++;
  81                 else
  82                         index = fFirst++;
  83
  84                 if (fBuffer != NULL)
  85                         fBuffer[index % fSize] = item;
  86         }
  87
  88         size_t Size() const
  89         {
  90                 return fSize;
  91         }
  92
  93 private:
  94         uint32          fFirst;
  95         uint32          fIn;
  96         uint32          fSize;
  97         Type*           fBuffer;
  98 };
  99
 100
 101 #endif  // CIRCULAR_BUFFER_H