Buffer Port Attributes and API - 2025.2 English - UG1079

You can configure the following attributes on buffer ports:

• Size
• Margin
• Locking protocol (synchronous or asynchronous)
• Addressing mode (linear or circular)
• Single buffer versus ping-pong-buffer

The kernel function signature specifies margin, locking protocol and addressing mode. The graph specifies single buffer versus ping-pong buffer.

You can specify the size of a buffer port in either the kernel signature or in the graph constructor. If the kernel function signature does not specify a size or uses adf::inherited_extent, you must define the size in the graph using the dimensions() API. The dimensions() API is used in the constructor of the graph and configures buffer port size in terms of the number of samples.

adf::inherited_extent, represents the size of the buffer which is inferred from the context, for example, it is inferred from the specification in the graph.

The buffer port margin represents the number of samples copied from the end of one block to the beginning of the next one. If a margin parameter is specified, the total memory allocated is:

In the case of a circular output buffer, you can specify the margin can be specified as adf::inherited_margin. In this case, the sink connected to this output port specifies the margin size.

Following is an example function prototype specifying margin size:

simple(input_buffer<int32, adf::extents<adf::inherited_extent>, 
        adf::margin<MARGIN_SIZE>> & in0,
        output_buffer<int32> & out0);