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

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  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() : mpRingBuffer(nullptr), mNumEntries(0), mRingHead(0), mRingTail(0) {}
  37
  38     ~RingBuffer() { Destroy(); }
  39
  40     void Init(uint32_t numEntries)
  41     {
  42         SWR_ASSERT(numEntries > 0);
  43         SWR_ASSERT(((1ULL << 32) % numEntries) == 0,
  44                    "%d is not evenly divisible into 2 ^ 32.  Wrap errors will occur!",
  45                    numEntries);
  46         mNumEntries  = numEntries;
  47         mpRingBuffer = (T*)AlignedMalloc(sizeof(T) * numEntries, 64);
  48         SWR_ASSERT(mpRingBuffer != nullptr);
  49         memset((void*)mpRingBuffer, 0, sizeof(T) * numEntries);
  50     }
  51
  52     void Destroy()
  53     {
  54         AlignedFree(mpRingBuffer);
  55         mpRingBuffer = nullptr;
  56     }
  57
  58     T& operator[](const uint32_t index)
  59     {
  60         SWR_ASSERT(index < mNumEntries);
  61         return mpRingBuffer[index];
  62     }
  63
  64     INLINE void Enqueue()
  65     {
  66         mRingHead++; // There's only one producer.
  67         // Assert to find wrap-around cases, NEVER ENABLE DURING CHECKIN!!
  68         // SWR_REL_ASSERT(mRingHead);
  69     }
  70
  71     INLINE void Dequeue()
  72     {
  73         InterlockedIncrement(&mRingTail); // There are multiple consumers.
  74     }
  75
  76     INLINE bool IsEmpty() { return (GetHead() == GetTail()); }
  77
  78     INLINE bool IsFull()
  79     {
  80         uint32_t numEnqueued = GetHead() - GetTail();
  81         SWR_ASSERT(numEnqueued <= mNumEntries);
  82
  83         return (numEnqueued == mNumEntries);
  84     }
  85
  86     INLINE uint32_t GetTail() volatile { return mRingTail; }
  87     INLINE uint32_t GetHead() volatile { return mRingHead; }
  88
  89 protected:
  90     T*       mpRingBuffer;
  91     uint32_t mNumEntries;
  92
  93     OSALIGNLINE(volatile uint32_t) mRingHead; // Consumer Counter
  94     OSALIGNLINE(volatile uint32_t) mRingTail; // Producer Counter
  95 };