Integration by Encapsulation

To encapsulate a tool:

• Write an encapsulation script based on the Encapsulation Procedures
• Invoke the tool with the FlowTracer Wrappers vw or with vw2.

For example, if your design flow includes the invocation of yacc as in:

% yacc -d -t cc.y

You would activate tracing by prefixing the above command with vw as in:

% vw yacc -d -t cc.y

The encapsulation script is a Tcl script whose name is derived from the name of the encapsulated tool by prepending vov_ and appending .tcl. For example, the encapsulation script for the tool yacc is called vov_yacc.tcl and looks like this:

set FILEPREFIX "y"
while { [arglength] > 1 }  {
    set arg [shift]
    switch -- $arg {
        "-d" { VovOutput "$FILEPREFIX.tab.h"  }
        "-t" {}
        "-b" { set FILEPREFIX [shift] }
        default {
            VovFatalError "Unknown option $arg" 
        }
    }
}
VovInput  [shift]
VovOutput "$FILEPREFIX.tab.c"

The FlowTracer wrapper vw looks for the encapsulation script in the following directories:

• In the property "CAPSULE" attached to the job (see Capsule On-the-Fly)
• In the current working directory
• In the directories indicated by the environment variable VOV_CAPSULE_DIR, if it exists; the directory names are separated by a colon on UNIX and by a semicolon on Windows NT
• In the directory $VOVDIR/local/capsules
• In the directory $VOVDIR/tcl/vtcl/capsules

Encapsulation is a simple and effective method to integrate any tool. While the encapsulation of some tools may be extremely complex, the majority of the capsules consists of very few lines of Tcl code. For example, say we are interested in encapsulating a tool called simulator that has the following command line:

simulator INPUT_FILE OUTPUT_FILE

The capsule for such tool may look like this:

# This is vov_simulator.tcl
VovInput [shift]
VovOutput [shift]