Technical data

Using the VHDL FLI with foreign architectures

456

VHDL Foreign Language Interface and Verilog PLI ModelSim EE/PLUS Reference Manual

Note:

Although compilation and simulation switches are platform-specific, references to load shared

objects are the same for all platforms. For information on loading objects see "Declaring the FOREIGN

attribute" (p456), "Declaring the subprogram in VHDL" (p458) for the FLI , and "Specifying the PLI file to

load" (p483) for the PLI.

Using the VHDL FLI with foreign architectures

To use the interface, you first create and compile an architecture with the

FOREIGN attribute. The string value of the attribute is used to specify the name

of a C initialization function, and the name of an object file to load. When VSIM

elaborates the architecture, the initialization function will be called. Parameters to

the function include a list of ports and a list of generics, see: "Mapping to VHDL

data types" (p481).

A foreign architecture body may contain only the foreign attribute declaration and

specification. Any other declarations or statements are ignored. In addition, only

the port clause and generic clause of the corresponding entity are accessible to the

foreign architecture. Any other entity declarations are ignored.

Declarin

the FOREIGN attribute

Starting with VHDL93, the FOREIGN language attribute is declared in package

STANDARD. With the 1987 version, you need to declare the attribute yourself.

You can declare it in a separate package, or you can declare it in the architecture

that you are replacing. (This will continue to work even with VHDL93).

The FOREIGN attribute string

The value of the FOREIGN attribute is a string in three parts. For the following

declaration:

ATTRIBUTE foreign OF arch_name : ARCHITECTURE IS "app_init app.so; parameter";

the attribute string parses this way:

app_init

The name of the initialization function for this architecture. This part is required. See "The

C initialization function" (p457).

app.so

The path to the shared object file to load. This part is required. See "Location of shared

object files" (p457).