Re: [sv-bc] Mantis 1573

Shalom, this one I will object to.

You have:
    If not coerced to inout, a warning shall be issued. If coercion does
    not occur, the additional assignment to the signal sink occurs, but
    the port direction is preserved and the assignment does not pass through
    the port connection to the signal source.

This does not allow for a collapsing approach since you have:
    "If coercion does not occur..."

At the very least this must be something like, "If an implementation
neither coerces such a port nor collapses it, the addiitonal...."

Gord.

Bresticker, Shalom wrote:
> I have uploaded yet another version of this.
> 
> Shalom 
> 
>> -----Original Message-----
>> From: Bresticker, Shalom 
>> Sent: Friday, December 14, 2007 11:34 AM
>> To: sv-bc
>> Subject: RE: [sv-bc] Mantis 1573
>>
>> I want to emphasize again that the original purpose of this 
>> Mantis is to clarify what is meant by "an input(output) used 
>> as an output(input)" in its most common form (not PLI or 
>> hierarchical reference) and what is the behavior if coercion 
>> does not occur. 
>>
>> The phrase has very frequently been misunderstood, even by 
>> committee members, and the behavior if coercion does not 
>> occur is completely unspecified by the LRM.
>>
>> So from the point of view of users, this issue is important.
>>
>> I'm going to make another try at wordsmithing this proposal.
>>
>> Shalom
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> ------------------------------------------------------------------------
> 
> Mantis 1573
> 
> P1800-2008/D4, 22.3.3.1
> 
> Clarify input used as output and vice-versa
> 
> CHANGE
> 
> *22.3.3.1 Port coercion*
> 
> A port that is declared as input (output) but used as an output (input) 
> or inout may be coerced to inout. If not coerced to inout, a warning 
> shall be issued.
> 
>  
> 
> TO
> 
> *22.3.3.1 Port coercion*
> 
> A port that is declared as input (output) but used as an output (input) 
> or inout may be coerced to inout. If not coerced to inout, a warning 
> shall be issued.
> 
>  
> 
>  
> 
>  
> 
> CHANGE
> 
> *22.3.3.7 Port connections with dissimilar net types (net and port 
> collapsing)*
> 
> * *
> 
> *TO*
> 
> *22.3.3.76** Port** connections with dissimilar net types (net and port 
> collapsing)*
> 
>  
> 
>  
> 
> ADD NEW
> 
> *22.3.3.7 Port coercion*
> 
>  
> 
> When both sides of an input or output port are nets and there is an 
> additional assignment to the port connection signal sink other than 
> through the port connection (i.e., input port used as an output or 
> output port used as an input), the port may be coerced to inout. If not 
> coerced to inout, a warning shall be issued. If coercion does not occur, 
> the additional assignment to the signal sink occurs, but the port 
> direction is preserved and the assignment does not pass through the port 
> connection to the signal source.
> 
>  
> 
> Example of an input port used as an output and of an output port used as 
> an input:
> 
>  
> 
> *module* top ;
> 
> *wire* in1, out1 ;
> 
> m m(in1, out1);
> 
> *assign* out1 = 1’b1;
> 
> *endmodule***
> 
>  
> 
>  
> 
> *module* m (in1, out1) ;
> 
> *input* in1 ;
> 
> *output* out1;        // out1 is driven outside the module and thus used 
> as an input
> 
> *assign* in1 = 1’b0 ; // in1 is driven within the module and thus used 
> as an output
> 
> *endmodule***
> 
>  
> 

-- 
--------------------------------------------------------------------
Gordon Vreugdenhil                                503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com


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