Buffer Port Attributes and API - 2025.1 English - UG1079

Attributes on buffer ports that can be configured are the buffer port's size, margin, locking protocol (synchronous or asynchronous), addressing mode (linear or circular), and single buffer versus ping-pong-buffer. Of these attributes, margin, locking protocol and addressing mode are specified in the kernel function signature. Single buffer versus. ping-pong buffer is specified in the graph.

The size of a buffer port can be specified either in the kernel signature or in the graph constructor. If the kernel function signature does not specify the size or if it is specified to be adf::inherited_extent, then the size must be specified 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 the sum of sample size and margin size, multiplied by template data type in number of bytes ( (sample size + margin size) * sizeof (data type)). In the case of a circular output buffer, the margin can be specified as adf::inherited_margin. In this situation, the margin size is specified by the sink connected to this output port.

An example function prototype specifying margin size follows:

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