Implement in behavioral the abs/min/max operators for real values.
The parser treats these builtin functions as operators, unary or
binary, and elaborates them appropriately.
Also add enough code generator support to handle real valued expressions
in thread context.
Verilog-AMS recommends that users use the system-function style
math functions, but supports traditional style math functions for
portability. Add the keywords and parse the traditional Verilog-A
functions, and handle them as calls to the equivilent system
function.
The begin_keywords directives manage a mask of keyword sets that are
active at a given moment. This patch makes the lexor actually test
the given keyword against the mask. If it matches, return the keyword
id, if it is disabled then it is an IDENTIFIER.
The begin_keywords directive allows the source code to select keyword
subsets so that a bit of code that uses identifiers that class with a
newer version of the standard can still be compiled.
Stephen Williams
steve