28.14.4.1.2. Descriptor Interface
The descriptor interface is configurable to either 128-bit wide for standard descriptor format, or 256-bit wide for extended descriptor format when parameter Enable Extended Feature Support is enabled. When writing descriptors to this interface, you must set the last bit high so the descriptor can be completely written to the dispatcher module.
Avalon® -MM Descriptor Agent Interface (descriptor_slave)
The descriptor agent interface allows write-only access. You can access the byte lanes of this interface in any order, as long as the last bit is written during the last write access.
| Signal Name | Direction | Type | Description |
|---|---|---|---|
| descriptor_slave_write | Input | Avalon® Memory-Mapped Agent | Write transfer into the descriptor FIFO. |
| descriptor_slave_byteenable [15:0] or [31:0] | Input | Enable the byte lanes during write transfer into the descriptor FIFO. | |
| descriptor_slave_writedata [127:0] or [255:0] | Input | Data of the descriptor write transfer into the descriptor FIFO. Refer to the Descriptor Format (without Prefetcher) section for data definition. Standard descriptor: 128-bit width Extended descriptor: 256-bit width |
|
| descriptor_slave_waitrequest | Output | mSGDMA IP asserts waitrequest when unable to respond to the descriptor write request. |
Avalon® -ST Descriptor Sink Interface (descriptor_sink)
This interface is used to receive streaming descriptor information from the prefetcher core.
| Signal Name | Direction | Type | Description |
|---|---|---|---|
| snk_descriptor_ready | Output | Avalon® Streaming Sink | Avalon® -ST ready control with ready latency of 0. Used to backpressure the descriptor streaming source from Prefetcher. |
| snk_descriptor_valid | Input | Avalon® -ST valid control. Indicates that the descriptor information from Prefetcher is valid. | |
| snk_descriptor_data [127:0] or [255:0] | Input | Avalon® -ST data bus. Refer to the Descriptor Format section for data definition. Standard descriptor: 128-bit width Extended descriptor: 256-bit width |