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From: savel@hoss.unl.edu (Bharat P. Savel)
Newsgroups: comp.lang.vhdl
Subject: Re: subprograms with waits
Message-ID: <1991Mar14.160402.15805@hoss.unl.edu>
Date: 14 Mar 91 16:04:02 GMT
References: <144030@<1991Mar12> <381900009@inmet>
Sender: news@hoss.unl.edu (Network News Administer)
Organization: Dept. of EE, Univ. of Nebraska-Lincoln
Lines: 31

In article <381900009@inmet> davidb@inmet.inmet.com writes:
>
>/* Written  9:40 am  Mar 12, 1991 by hughes@eng3.hep.uiuc.edu */
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>A couple of common errors to avoid:
>
>o The subprogram must be a procedure.  Inout parameters to functions
>are not allowed.
>
>o Make sure that the parameter list in the procedure declaration
>specifies the class of the parameter as signal.  This is often
>omitted, as the class of subprogram parameters is usually defaulted
>and the modes usually give enough information as to use.
>
>o Pass all the signals to which you will be assigning values as
>parameters.  Inheriting visibility to signals is tricky; the only
>place you can really do it is in a process statement.
----------
another point is the side effects of a sub-program; try to avoid the same 
signal names in the subprogram and in the architecture-calling-it; seems that 
things get screwy then;
--
-------------------------------------------------------------------------------
Bharat P. Savel
EE Dept.                                       E-mail : savel@hoss.unl.edu
Univ of Nebraska-Lincoln                           Ph : (617) 983-0850