Language Change Specification for Interface Construct and Port Mode Configurations Proposal

Primary LCS:

This LCS details the minimum support required for a mode view interface construct at the RTL.

LCS-2016-045a.1

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• Removed Generics
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Revision 3 21-Mar-17

• Added Generics

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LCS Intent

Details of Language Change:

3.2.3 Entity declarative part

page 8 bottom *Edit:* Add mode_view_declaration as a declarative item

entity_declarative_item ::=
   [beginning items unchanged]
   | type_declaration
   | subtype_declaration
   | mode_view_declaration
   | constant_declaration
   [remaining items unchanged]

3.3.2 Architecture declarative part

page 11 bottom *Edit:* Add mode_view_declaration as a declarative item

block_declarative_item ::=
   [beginning items unchanged]
   | type_declaration
   | subtype_declaration
   | mode_view_declaration
   | constant_declaration
   [remaining items unchanged]

4.3 Subprogram bodies

page 23 bottom *Edit:* Add mode_view_declaration as a declarative item

LRM 4.7 Package declarations

page 30 middle *Edit:* Add mode_view_declaration as a declarative item

package_declarative_item ::=
   [beginning items unchanged]
   | type_declaration
   | subtype_declaration
   | mode_view_declaration
   | constant_declaration
   [remaining items unchanged]

4.8 Package bodies

page 32 top *Edit:* Add mode_view_declaration as a declarative item

6.3 Subtype declarations

Add paragraph following 3 paragraph(shown below) where BNF = 1 paragraph

A subtype that has a resolution indication is called a resolved subtype. A type or subtype that does not have a resolution indication is called an unresolved type or unresolved subtype respectively.

LRM 6.5.2 Interface object declarations

Add new section title on page 73 middle

page 73 middle, *Edit:* Revise BNF productions as follows:

interface_object_declaration ::=
     interface_constant_declaration
   | interface_signal_declaration
   | interface_variable_declaration
   | interface_file_declaration

interface_constant_declaration ::=
     [ constant ] identifier_list : [ in ] subtype_indication [ := static_expression ]

interface_signal_declaration ::=
     [ signal ] identifier_list : [ mode ] subtype_indication [ bus ] [ := static_expression ] signal_mode_indication

interface_variable_declaration ::=
     [ variable ] identifier_list : [ mode ] subtype_indication [ := static_expression ] variable_mode_indication

interface_file_declaration ::=
     file identifier_list : subtype_indication

mode_indication ::=
     [ mode ] subtype_indication [ bus ] [ := static_expression ] 
   | mode_view_indication

mode ::= in | out | inout | buffer | linkage

mode_view_indication ::=
     view mode_view_name [ of unresolved_composite_subtype_indication ]

Edit: page 73 last paragraph

For an interface constant declaration, if mode in is not explicitly given, it is assumed. For an interface signal or variable declaration, if a mode indication is not a mode view indication and no mode is explicitly given, mode in is assumed.

Edit: page 74 top, 3rd and 4th paragraph paragraph add paragraphs after 5th

1st paragraph no edits
For an interface constant declaration (other than a formal parameter of the predefined = or /= operator for an access type) or an interface signal declaration, the subtype indication shall define a subtype that is neither a file type, an access type, nor a protected type. Moreover, the subtype indication shall not denote a composite type with a subelement that is of an access type.

2nd paragraph no edits
For an interface file declaration, it is an error if the subtype indication does not denote a subtype of a file type.

3rd paragraph with edits
If the mode indication of an interface signal declaration includes the reserved word bus, then the signal declared by that interface declaration is a guarded signal of signal kind bus. It is an error if the mode indication of an interface variable declaration includes the reserved word bus.

4rd paragraph with edits
If an interface constant declaration or the mode indication of an interface signal or constant declaration contains a ":=" symbol followed by an expression, the expression is said to be the default expression of the interface object. The type of a default expression shall be that of the corresponding interface object. It is an error if a default expression appears in an interface declaration or a mode indication of an interface declaration and any of the following conditions hold:
- The mode is linkage.
- The interface object is a formal signal parameter.
- The interface object is a formal variable parameter of mode other than in.
- The subtype indication of the interface declaration denotes a protected type.

5rd paragraph no edits
In an interface signal declaration appearing in a port list, the default expression defines the default value(s) associated with the interface signal or its subelements. In the absence of a default expression, an implicit default value is assumed for the signal or for each scalar subelement, as defined for signal declarations (see 6.4.2.3). The value, whether implicitly or explicitly provided, is used to determine the initial contents of drivers, if any, of the interface signal as specified for signal declarations.

New paragraph after 5th paragraph (above)
A mode view indication allows each element of a composite to have a different interface mode. Each element of the composite with its respective mode declared in the mode view indication is equivalent to each element being declared as a formal signal port with the mode and type or subtype of the respective composite element.

remaining paragraphs of the section are unedited, 6th paragraph below provided for reference
In an interface signal declaration appearing in a port list, the default expression defines the default value(s) associated with the interface signal or its subelements. In the absence of a default expression, an implicit default value is assumed for the signal or for each scalar subelement, as defined for signal declarations (see 6.4.2.3). The value, whether implicitly or explicitly provided, is used to determine the initial contents of drivers, if any, of the interface signal as specified for signal declarations.

Edit: 3rd paragraph on page 75

The mode of an interface object or a mode view declaration has one of the following modes:

add new section just before 6.5.3 and after Note 8 on page 75 bottom

Additions to 6.5.2.2 (new section)

Add the following

mode_view_declaration ::=
     view identifier of unresolved_composite_subtype_indication is
          { mode_view_element_definition }
     end view [ mode_view_simple_name ] ;

mode_view_element_definition ::=
     composite_element_list : element_mode_indication  ;

composite_element_list ::=
     composite_element_choice { , composite_element_choice }
     
element_mode_indication ::=
     mode  
   | mode_view_indication

entity_class ::=
      [all unspecified items are unchanged]
      | sequence
      | view

composite_element_list ::=                                              [§ 6.5.2.1.1]
     composite_element_choice { , composite_element_choice }

entity_class ::=                                                        [§ 7.2]

interface_signal_declaration ::=                                        [§ 6.5.2]

interface_variable_declaration ::=                                      [§ 6.5.2]

mode_indication ::=                                                     [§ 6.5.2]

mode_view_declaration ::=                                               [§ 6.5.2.1.1]

mode_view_element_definition ::=                                        [§ 6.5.2.1.1]

mode_view_header ::=                                                    [§ 6.5.2.1.1]

mode_view_indication ::=                                                [§ 6.5.2]

package_declarative_item ::=                                            [§ 4.7]