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         SWR_ASSERT(((1ULL << 32) % numEntries) == 0, "%d is not evenly divisible into 2 ^ 32.  Wrap errors will occur!", numEntries);
  50         mNumEntries = numEntries;
  51         mpRingBuffer = (T*)AlignedMalloc(sizeof(T)*numEntries, 64);
  52         SWR_ASSERT(mpRingBuffer != nullptr);
  53         memset(mpRingBuffer, 0, sizeof(T)*numEntries);
  54     }
  55
  56     void Destroy()
  57     {
  58         AlignedFree(mpRingBuffer);
  59         mpRingBuffer = nullptr;
  60     }
  61
  62     T& operator[](const uint32_t index)
  63     {
  64         SWR_ASSERT(index < mNumEntries);
  65         return mpRingBuffer[index];
  66     }
  67
  68     INLINE void Enqueue()
  69     {
  70         mRingHead++; // There's only one producer.
  71         // Assert to find wrap-around cases, NEVER ENABLE DURING CHECKIN!!
  72         // SWR_REL_ASSERT(mRingHead);
  73     }
  74
  75     INLINE void Dequeue()
  76     {
  77         InterlockedIncrement(&mRingTail); // There are multiple consumers.
  78     }
  79
  80     INLINE bool IsEmpty()
  81     {
  82         return (GetHead() == GetTail());
  83     }
  84
  85     INLINE bool IsFull()
  86     {
  87         uint32_t numEnqueued = GetHead() - GetTail();
  88         SWR_ASSERT(numEnqueued <= mNumEntries);
  89
  90         return (numEnqueued == mNumEntries);
  91     }
  92
  93     INLINE uint32_t GetTail() volatile { return mRingTail; }
  94     INLINE uint32_t GetHead() volatile { return mRingHead; }
  95
  96 protected:
  97     T* mpRingBuffer;
  98     uint32_t mNumEntries;
  99
 100     OSALIGNLINE(volatile uint32_t) mRingHead;  // Consumer Counter
 101     OSALIGNLINE(volatile uint32_t) mRingTail;  // Producer Counter
 102 };