Date: Tue Oct 10 2006 - 14:24:51 PDT
Shalom, Someone forwarded me a list of enhancements that are being talked about in the OVL and possibly the SV-AC committees. I don't know if this is related to your request, but it seems to me they are creating a whole new language using macro syntax, and I find it horrible that someone would propose different macro functionality for different parts of the language. My basic objection to macros is that they are very difficult to debug, and they are usually there as a hack to cover up a language deficiency. I'd rather spend the effort addressing the original need, and staying away from the use of macros. One other point for this particular enhancement is with defaults values is that it is not very readable without pass by name. I think we have already shown that the pass by name syntax is not backward compatible with existing Verilog code. Dave Attached: From: Korchemny, Dmitry [mailto:dmitry.korchemny@intel.com] Sent: Monday, October 09, 2006 12:18 AM To: ovl-vsva@lists.accellera.org Subject: [ovl-vsva] SVA extensions compatible with module packaging Hi all, I was asked to send a list of proposed SVA extension features that OVL may benefit when OVL checkers are still packaged into modules/interfaces. I would like to mention, however, that using modules/interfaces for this purpose leads to the flexibility loss - no context inference, no possibility to pass a property/sequence as an argument. Therefore most of the proposed extensions are not relevant for modules, and the list is very poor. Cosmetic changes in the OVL checker invocation may be done using enhancements in the compiler directives: * Default argument values in a macro * Passing macro argument by name * Repeatable macro arguments E.g., the invocation of the checker assert_delta assert_delta #(OVL_ERROR, 16, 0, 8, OVL_ASSERT, "Error: y values not smooth", OVL_COVER_ALL) valid_smooth ( clk, reset_n, y ); may the look like: `ASSERT_DELTA(valid_smooth, y, .width(16), .max(8), .msg("Error: y values not smooth")); A very important feature is an ability to specify user-defined compile-time messages: Compare: // Compile-time message when module parameter is wrong if (num_cks < 2) $error("Illegal value set for action_on_new_start"); instead of a run-time message as now: initial begin if (num_cks < 2) ovl_error_t("Illegal value set for action_on_new_start"); end A proposal concerning property modeling is also beneficial for OVL, since it eliminates races which occur when RTL is used for the modeling. The problem is that in my proposal the modeling code may be specified inside checkers (new construct for property packaging) only, and not within modules. Regards, Dmitry ________________________________ From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org] On Behalf Of Bresticker, Shalom Sent: Tuesday, October 10, 2006 6:29 AM To: sv-bc@server.eda.org Subject: FW: [sv-bc] Mantis 1571: Add default values for macro arguments Resend. Comments? Shalom ________________________________ From: owner-sv-bc@server.eda.org [mailto:owner-sv-bc@server.eda.org] On Behalf Of Bresticker, Shalom Sent: Sunday, September 17, 2006 2:53 PM To: sv-bc@server.eda-stds.org Cc: Korchemny, Dmitry Subject: [sv-bc] Mantis 1571: Add default values for macro arguments This is a draft proposal for Mantis 1571, to add default values for macro arguments. The obvious advantage of default values for macro arguments is not having to specify them, making their usage shorter and more readable. A second advantage is being able to change the default by a single change instead of having to change the argument value in every usage of the macro. Syntax change: Change the syntax in Syntax 19-2 in 1364-2005 from list_of_formal_arguments ::= formal_argument_identifier { , formal_argument_identifier } formal_argument_identifier ::= simple_identifier to list_of_formal_arguments ::= formal_argument { , formal_argument } formal_argument ::= simple_identifier [ = default_value ] (Note that the default value does not have to be an expression syntactically. This is noted in Mantis 1333.) Add the following text: A formal macro argument may have a default value. If a default value is not explicitly specified, then the macro argument is considered to have a null default value. The default value is substituted for the formal argument if no corresponding actual argument is specified. If fewer actual arguments are specified than the number of formal arguments, then the default values are substituted for the additional formal arguments. It shall be an error to specify more actual arguments than the number of formal arguments in the macro. Examples: `define MACRO(a=5,b="B",c) $display( a ,, b ,, c ) ; // c has no explicit default, implicit null default `MACRO ( , 2, 3 ) // argument a omitted `MACRO ( 1 , , 3 ) // argument b omitted `MACRO ( , 2, ) // arguments a and c omitted `MACRO ( 1 ) // arguments b and c omitted `MACRO () // all three arguments omitted Shalom Shalom Bresticker Intel Jerusalem LAD DA +972 2 589-6852 +972 54 721-1033 I don't represent Intel
