RE: [sv-bc] part selects on arbitrary expressions

When you write that the 'operand of the parentheses is
context-determined', do you mean that the expression within the
parentheses is context-determined in the sense that the types of the
operands inside are influenced by the other operands within the
parentheses? 

 

Shalom

 

________________________________

From: Feldman, Yulik 
Sent: Sunday, March 11, 2007 6:27 PM
To: Bresticker, Shalom; 'sv-bc@server.eda.org'
Subject: RE: [sv-bc] part selects on arbitrary expressions

 

Probably I was not clear enough; I hoped the previous discussion made it
clear. 

 

If we consider the parenthesis as a fully syntactic sugaring (which it
is), then we have only two expressions: the part select operator and its
operand. This operand is always self-determined and this is the end of
the definition.

 

If we consider the parenthesis as a kind of "identity" operator, then we
have three expressions: the part select operator, the parenthesis
operator (which is the operand of the part select) and the selected
expression (which is the operand of the parenthesis). The operand of the
part select is always self-determined and the operand of the parenthesis
is always context-determined. This definition is semantically equivalent
to the previous definition, w.r.t. to the inferred types. So, it doesn't
matter how you look on it, the operand of the part select is (should be)
always self-determined, and the "operand" of the parenthesis "operator"
should be context-determined (if you choose to treat the parenthesis as
an operator).

 

--Yulik.

 

________________________________

From: Bresticker, Shalom 
Sent: Sunday, March 11, 2007 5:40 PM
To: Feldman, Yulik; sv-bc@server.eda.org
Subject: RE: [sv-bc] part selects on arbitrary expressions

 

I think those last two bullets are contradictory.

 

Shalom

 

*  The parenthesis "()" in Verilog is a kind of syntactic sugaring, in a
sense that the type of the ()'s "result" is always exactly the same as
the type of its "operand". The "operand" of () is always
context-determined. 

*  The syntax of (expr)[a][b][c] for the part select operator (where the
parenthesis may be optional for certain kinds of selected expression)
seem to be the most succinct and flexible syntax suggested, even though
several committee members raised concerns about ability of an uninformed
reader to infer that the "first operand" of the part select given in
such syntax ("(expr)") is self-determined. 


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