Proposal for two additional environment parameter functions

Hello,
I would like to propose two new environment parameter functions for LRM 2.3

1. $freq
Similar to $abstime, this function will simply return the current frequency
when doing a small-signal analysis.

[LRM TEXT]
$freq shall return the current frequency used of a small-signal analysis. The
function shall return zero (0) during DC or transient analysis.


2. $simprobe(instance, param_name [, expression])
Similar to $simparam(), this function will retrieve the value  of a given
parameter from a given instance. If the instance/parameter does not exist, it
will stop with an error. If the optional argument <expression> is specified, it
will return this value in lieu of the error. This function is not limited to
retrieving values from Spice elements, but also Verilog-AMS instances.

[LRM TEXT]
$simprobe() allows the user to query the value of an element within the
specified instance. The function returns a real scalar value.
The general form of the $simprobe function is:
	$simprobe(instance, param_name [, expression])
	
<instance> is a string constant (either a literal or string parameter). If the
string is prefixed with a '.' character, then the characters following the '.'
character make up the full hierarchical name of the instance to query. If the
first character of the instance string is not a '.', then the string is the
local name of the instance to query. It is a compilation error to use a
hierarchical instance name where the string is not prefixed with a '.' character.

<param_name> is the name of the parameter whose value is required. It is a
string constant (either a literal or string parameter). A parameter can be any
valid scalar or indexed vector output parameter for the instance in question.

<expression> is an optional argument. It can be any valid Verilog-AMS
expression. When specified, its value will be returned in case of an error.

When <instance> is specified in the hierarchical form, <param_name> will be
retrieved from <instance>. If <instance> or <param_name> does not exist an
error will be raised. If <expression> has been specified, it's value will be
returned in lieu of raising the error.

Example:
module grandchild();
   parameter string inst = ".atop.ch";
   analog $strobe("%m: Value of '%s' is %g", inst, $simprobe(inst,"x"));
endmodule
module child();
   real x;
   grandchild gc();
   analog x = 10;
endmodule
module top();
   real x;
   child ch();
   analog x = 5.0;
endmodule

Here (assuming that the top level module top is instantiated as "atop") module
grandchild() is asking for the value of 'x' from the instance whose
hierarchical name is "atop.gc" The above example will print the following message:
   atop.ch.gc: Value of '.atop.ch' is 10.0

When <instance> is not specified in the hierarchical form, the hierarchy will
be search upwards to find a local instance name that matches. Once the instance
  name has been matched, the value of <param_name> will be retrieved from that
instance. If <param_name> does not exist in the resolved instance, an error
will be raised (or <expression> returned if it has been specified).

Example:
module grandchild();
   parameter string inst = "atop";
   analog $strobe("%m: Value of '%s' is %g", inst, $simprobe(inst,"x"));
endmodule
module child();
   real x;
   grandchild gc();
   analog x = 10;
endmodule
module top();
   real x;
   child ch();
   analog x = 5.0;
endmodule

Here module grandchild() is asking for the value of 'x' from the instance whose
  local name is "atop". The simulator will search up the hierarchy looking for
an instance called "atop". Once it finds "atop" the value of "x" is obtained.
If "atop" does not exist in the hierarchy or did not contain a output parameter
call "x", then an error is raised (or <expression> is returned if specfied).
The above example will print the following message:
   atop.ch.gc: Value of 'atop' is 5.0


-- 
=====================================
-- David Miller
-- Design Technology (Austin)
-- Freescale Semiconductor
-- Ph : 512 996-7377 Fax: x7755
=====================================


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