Comments to the LCS 201x-03 (Architecture Statements)

Alain Vachoux
alain.vachoux@epfl.ch

July 8, 2015


Structure of Clause 11
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Grouping architecture statements in three logical categories, namely structural statements, concurrent statements, and simultaneous statements, clearly specifies the kinds and roles of the statements allowed in an architecture body. There is no need, however, to have a clause structure that strictly follows the logical groups. As the LCS says, the BNF syntax does the job, so a flat structure would be OK. A LRM is not a tutorial document.

The introduction of the new category of structural statements that actually also impacts the 1076 standard. Ideally, this should be also included in the 1076 LRM for maintaining the consistency between the 1076 and the 1076.1 LRMs. But this is not a blocking issue.


New section 3.3.3 (Architecture statement part)
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The last paragraph seems to include a footnote numbered 7, which I'm not sure it is really required.


New section 11.1 (General)
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"Structural statements provide syntax for representing structural decomposition of a model."

   I think the statements could also represent a "structural composition". Maybe a better term would be "structural organization".

"The primary structural statement is the block statement, which groups together other architecture statements. Each structural statement is equivalent to zero, one, or two nested blocks that jointly describe the overall structure of a design."

   I do not clearly see why the maximum number of nested blocks is limited to two. I would remove the the last part of the last sentence "that jointly describe the overall structure of a design". This is already said (differently) when structural statements are introduced.

"Concurrent statements are used to define interconnected blocks and processes that may be interconnected with structural statements. Jointly with simultaneous statements concurrent statements describe the overall behavior of a design. Concurrent statements execute asynchronously with respect to each other."

   I think a comma is missing in "Jointly with simultaneous statements, concurrent statements..."

"Simultaneous statements express explicit differential and algebraic equations that together with implicit equations constrain the values of the quantities of a model. Simultaneous statements may be interconnected with structural statements."

   I'm not sure what "interconnected" actually means here. To me, "interconnected" means that there is a kind of channel identified by ports between two entities.

"NOTE—The subsections in this clause related to structural statements and concurrent statements are presented in the same order as in the VHDL 1076 language reference manual to avoid perturbing the numbering scheme. They are followed by subsections related to simultaneous statements."

   Is this note really required in the LRM?