Tiling parameter structure - 2023.2 English

Vitis Tutorials: AI Engine

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2023.2 English

The tiling_parametersstructure is defined as follows:

  struct tiling_parameters
      /// Buffer dimensions in buffer element type. buffer_dimension[0] is the fast-moving dimension and is contiguous in memory.
      /// When this variable is left unspecified, the dimensions of the associated buffer object will be used.
      std::vector<uint32_t> buffer_dimension;
      /// Tiling dimensions in buffer element type.
      std::vector<uint32_t> tiling_dimension;
      /// Multi-dimensional offset w.r.t. buffer starting element. Assuming buffer dimension is specified.
      std::vector<int32_t> offset;
      /// Vector of traversing_parameters. tile_traversal[i] represents i-th loop of inter-tile traversal,
      /// where i=0 represents most inner loop and i=N-1 represents most outer loop.
      std::vector<traversing_parameters> tile_traversal;
      /// Output port id of the connected pktsplit or the input port id of the connected pktmerge.
      int packet_port_id = -1;
      /// Number of repetitions of tiling traversal
      uint32_t repetition = 1;
      /// Phase of tiling parameter resource sharing and execution
      uint32_t phase = 0;
      /// Real data boundary dimension for padding
      std::vector<uint32_t> boundary_dimension;

One can see in this prameters all the global parameters of the transfer, but the order of the memory access is specified by the traversing_parameters:

struct traversing_parameters
      /// The dimension of the inter-tile traversing loop.
      uint32_t dimension = 0;
      /// stride represents the distance in terms of buffer element type between consecutive inter-tile traversal in the dimension
      uint32_t stride = 0;
      /// wrap represents the number of steps before wrapping the current traversing loop and incrementing to the next traversing loop.
      /// The traversal stops when the last wrap completes.
      uint32_t wrap = 0;

      bool operator==(const traversing_parameters& rhs) const
          return (dimension == rhs.dimension && stride == rhs.stride && wrap == rhs.wrap);

Actually a vector of traversing_parameters is describing the access order. This allows the user to specify any dimension-wise order, starting with dimension 3 if the data must be ordered that way.