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--- tools:start [2024/07/24 18:07] – [Tools] rajit
+++ tools:start [2025/05/20 11:52] (current) – rajit
@@ Line 35: / Line 35: @@
       * [[http://opencircuitdesign.com/netgen/index.html|netgen]]: another tool for LVS
-Two useful concepts to keep in mind when using the ACT tools are //expanded names// and //mangled names//.
+Two useful concepts to keep in mind when using the ACT tools are [[intro_example:name_mangling|expanded names and mangled names]].
-===== Expanded names =====
-A concept one should be familiar with, especially when debugging and/or understanding error messages is the notion of expanded names. This is best illustrated with an example. Consider the following templated process definition:
-<code act>
-template<pint A; pbool B; pint C[A]> defproc example(...) { ... }
-example<1+1,true,{1,5}> e1;
-example<1,false,{2}> e2;
-</code>
-The type of the process defined is ''example'', but the instances ''e1'' and ''e2'' include specific template parameters. After the design is expanded and all template parameters are substituted, different variations of ''example'' are created for ''e1'' and ''e2''. These //expanded// versions of types are given different names within the ACT framework.  In particular, the expanded type for ''e1'' would be ''example<2,t,{1,5}>'' (here ''t'' is used as a stand-in for the value of the Boolean parameter ''true'').  If ''example'' did not take on any template parameters, the expanded version of the type would be named ''example<>''.
-If the template list contains multi-dimensional arrays, the expanded name contains a linear list of the parameters separated by commas.
-===== Mangled names =====
-Expanded ACT type names can contain characters like ''<'','' >'', and '','' (among others). Instances can have names like ''a[3].b[5].z'', including the characters ''['', '']'', and ''.''. When exporting an ACT design to another format for use by a third-party tool, names with such characters in them can be potentially problematic. A good example of this is when exporting a SPICE netlist---different versions of SPICE have different syntactic restrictions. To handle this in a disciplined manner, the ACT library has the notion of a //mangled// name. A mangled name is generated by re-writing a user-specified list of special characters with an underscore and a number/character combination. This mapping is invertible, so a name can be unmangled as well. The set of characters to be mangled is specified in the ACT configuration option ''act.mangle_string'' (usually found in the global configuration file ''global.conf'').
-The standard name mangling prefix character is an underscore. Name mangling operates character-by-character as follows:
-   *  An underscore is replaced by two underscores.
-   * A character that is not in the mangle string is a pass-through, so it is not modified.
-   * If a character is at position k in the name mangling string, it is replaced with an underscore followed by k. The position character is 0 to 9 for positions 0 to 9, followed by a-z. Up to 36 characters can be mangled.
-Name mangling can at most double the length of the string.
-Process names have a special case in terms of name mangling. If an expanded process has no parameters, its mangled name is obtained simply be omitting the trailing ''<>''. This is to make the output more readable when templates are not being used.