Differences

This shows you the differences between two versions of the page.

--- language:langs:refine [2022/06/23 19:35]
rajit created
+++ language:langs:refine [2022/09/16 08:57] (current)
rajit
@@ Line 9: / Line 9: @@
 </code>
-This is used to provide an implementation of a process that replaces the CHP, dataflow, HSE, or PRS body.
+This is used to provide an implementation of a process that replaces the CHP, dataflow, HSE, or PRS body. For example, imagine you had a process defined at the CHP level
+<code act>
+defproc example (...)
+{
+   int x;
+   chp {
+      *[ L?x; R!x ]
+   }
+}
+</code>
+You can include its production-rule level description in the same process definition, as follows:
+<code act>
+defproc example (...)
+{
+   ...
+   chp {
+      *[ L?x; R!x ]
+   }
+   prs {
+      // circuit goes here
+   }
+ }
+</code>
+At this point, a tool can select the level of abstraction/detail for the process by picking one of the two sub-languages provided.
+Now imagine that instead of writing the production rules directly, you'd like to instantiate a set of gates to implement the circuit. Suppose we write the following:
+<code act>
+defproc example(...)
+{
+  ...
+  chp {
+    *[ L?x; R!x ]
+  }
+  inst1 i1;
+  inst2 i2;
+  // the other instances and connctions...
+}
+</code>
+As written, this means that the process has a CHP definition, and //in addition// it has the specified instances! This is not what we intended to specify; we'd like to use the CHP definition //or// the instances.
+To provide support for this, the ''refine'' body is used. The example would be written:
+<code act>
+defproc example(...)
+{
+  ...
+  chp {
+    *[ L?x; R!x ]
+  }
+  refine {
+     inst1 i1;
+     inst2 i2;
+     // the other instances and connctions...
+   }
+}
+</code>
+Now you can //pick// the refined version of the process by using the ACT command-line option ''-ref=1'', and so a tool can pick either the ''chp'' or the ''refine'' sub-language, giving us the desired effect.
+This approach is used in the ''chp2prs'' tool to provide an implementation of the CHP. This is the standard convention used in any tool that takes CHP and generates a circuit-level description. By augmenting the definition of the process in this manner, you can model the process at both the CHP level of abstraction as well as a more detailed representation containing a collection of instances that implement the CHP.