FIFO Constraint - 2021.2 English

Versal ACAP AI Engine Programming Environment User Guide (UG1076)

Document ID
UG1076
ft:locale
English (United States)
Release Date
2021-12-17
Version
2021.2 English

This constrains a FIFO to a specific tile located at a specified column and row within the array. The tile can be an AI Engine tile, memory tile, or interface tile. The bankId is optional; if omitted, the compiler selects an optimal bank.

The FIFO constraint can be specified in one of the following ways:

  • Column, row, bankID and offset, where the tile is specified by column, row, bankID, and the offset address is relative to the bankID, starting at zero with a maximum value of 8188 32-bit words of a bank.

  • Column, row, and bankId, where the bank ID is relative to the tile and can take values 0, 1, 2, or 3.

The following code block shows the syntax.

"PortConstraints": [<fifo list>]
<fifo list> ::= <fifo type>[, <fifo type>...]
<fifo type> ::= <dma_fifos> | <stream_fifos>
<dma_fifos> ::= <aie_tile>
<aie_tile> ::= {
  "fifo_id": string,
  "tile_type": "core",
  "column": integer,
  "row": integer,
  "size": integer,
  "offset": integer,
  "bankId":integer (optional)
}
<stream_fifos> ::= {
  "fifo_id": string,
  "tile_type": "shim",
  "column": integer,
  "row": integer,
  "channel": integer
}

The following code shows an example.

{
  "PortConstraints": {
    "fifo_locations_records": {
      "dma_fifos": {
        "r1": {
          "tile_type": "core",
           "row": 0,
           "column": 0,
           "size": 16,
           "offset": 8,
           "bankId": 2
        },
        "r2": {
          "tile_type": "core",
          "row": 0,
          "column": 1,
          "size": 16,
          "offset": 9
        },
        "r4": {
          "tile_type": "mem",
          "row": 2,
          "column": 4,
          "size": 16,
          "offset": 6,
          "bankId": 2
        }
      },
      "stream_fifos": {
        "r3": {
          "tile_type": "shim",
          "row": 1,
          "column": 3,
          "channel": 1
        }
      }
    },
    "mygraph.k2.in[0]": {
      "not_colocated_nodes": ["mygraph.k1"],
      "fifo_locations": ["r1", "r2", "r3"]
    },
    "mygraph.k4.in[0]": {
      "fifo_locations": ["r1", "r2", "r4"]
    }
  }
}