Question

Depending on the data types used for imported or exported tasks or functions, the C code can be binary-level or source-level compatible. Applications that do not use SystemVerilog packed types are always binary compatible. Applications that don’t mix SystemVerilog packed and unpacked types in the same data type can be written to guarantee binary compatibility. Open arrays with both packed and unpacked parts are also binary compatible.

The values of SystemVerilog packed types can be accessed via interface tasks or functions using the canonical representation of 2-state and 4-state packed arrays, or directly through pointers using the implementation representation. The former mode assures binary level compatibility; the latter one allows for tool-specific, performance-oriented tuning of an application, though it also requires recompiling with the implementation-dependent definitions provided by the vendor and shipped with the simulator.