src/gallium/drivers/swr/rasterizer/core/ringbuffer.h

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  22 *
  23 * @file arena.h
  24 *
  25 * @brief RingBuffer
  26 *        The RingBuffer class manages all aspects of the ring buffer including
  27 *        the head/tail indices, etc.
  28 *
  29 ******************************************************************************/
  30 #pragma once
  31
  32 template<typename T>
  33 class RingBuffer
  34 {
  35 public:
  36     RingBuffer()
  37         : mpRingBuffer(nullptr), mNumEntries(0), mRingHead(0), mRingTail(0)
  38     {
  39     }
  40
  41     ~RingBuffer()
  42     {
  43         Destroy();
  44     }
  45
  46     void Init(uint32_t numEntries)
  47     {
  48         SWR_ASSERT(numEntries > 0);
  49         mNumEntries = numEntries;
  50         mpRingBuffer = (T*)_aligned_malloc(sizeof(T)*numEntries, 64);
  51         SWR_ASSERT(mpRingBuffer != nullptr);
  52         memset(mpRingBuffer, 0, sizeof(T)*numEntries);
  53     }
  54
  55     void Destroy()
  56     {
  57         _aligned_free(mpRingBuffer);
  58         mpRingBuffer = nullptr;
  59     }
  60
  61     T& operator[](const uint32_t index)
  62     {
  63         SWR_ASSERT(index < mNumEntries);
  64         return mpRingBuffer[index];
  65     }
  66
  67     INLINE void Enqueue()
  68     {
  69         mRingHead++; // There's only one producer.
  70     }
  71
  72     INLINE void Dequeue()
  73     {
  74         InterlockedIncrement(&mRingTail); // There are multiple consumers.
  75     }
  76
  77     INLINE bool IsEmpty()
  78     {
  79         return (GetHead() == GetTail());
  80     }
  81
  82     INLINE bool IsFull()
  83     {
  84         ///@note We don't handle wrap case due to using 64-bit indices.
  85         ///      It would take 11 million years to wrap at 50,000 DCs per sec.
  86         ///      If we used 32-bit indices then its about 23 hours to wrap.
  87         uint64_t numEnqueued = GetHead() - GetTail();
  88         SWR_ASSERT(numEnqueued <= mNumEntries);
  89
  90         return (numEnqueued == mNumEntries);
  91     }
  92
  93     INLINE volatile uint64_t GetTail() { return mRingTail; }
  94     INLINE volatile uint64_t GetHead() { return mRingHead; }
  95
  96 protected:
  97     T* mpRingBuffer;
  98     uint32_t mNumEntries;
  99
 100     OSALIGNLINE(volatile uint64_t) mRingHead;  // Consumer Counter
 101     OSALIGNLINE(volatile uint64_t) mRingTail;  // Producer Counter
 102 };