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VHDL Object Model 1.0
---------------------
Copyright (c) 1993 Ohio Board of Regents and the University of
Cincinnati. All rights reserved.
Authors: David Benz, Phillip Baraona
E-Mail: dbenz@thor.ece.uc.edu, pbaraona@thor.ece.uc.edu
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#||
File: class-defns.re
Contains: Class definitions for VHDL object model.
Organization:
The object-class definitions are organized in a hierarchical manner
from most general to most specific. The top-level objects are at the top of
this file, such as VHDL-Design-File, Design-Unit, and the bottom-level objects
are towards the bottom, such as Expressions, Literals, etc. Also, we tried not
to break up chapters (of the VHDL LRM) except in the cases where it makes more
sense to do so. The specification also includes relevant chapter / section
pointers into the LRM.
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!! in-package("VOM-1-0")
!! in-grammar('user)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Object Hierarchy %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
var Vhdl-Object : object-class subtype-of user-object
var Syntactic-Object : object-class subtype-of vhdl-object
var Vhdl-Program : object-class subtype-of syntactic-object
%% Design Files (Sec. 11.1)
var VHDL-Design-File : object-class subtype-of syntactic-object
%% Design Units (Sec. 11.1)
var Design-Unit : object-class subtype-of syntactic-object
%% Context Items (Sec. 11.3)
var Context-Item : object-class subtype-of syntactic-object
var Library-Clause : object-class subtype-of context-item
%% Design Entities, Configurations and Packages (Chaps. 1 & 2)
var Library-Unit : object-class subtype-of syntactic-object
var Entity-Declaration : object-class subtype-of library-unit
var Architecture-Body : object-class subtype-of library-unit
var Configuration-Declaration : object-class subtype-of library-unit
var Package-Declaration : object-class subtype-of library-unit
var Package-Body : object-class subtype-of library-unit
%% Block Configuration (Sec. 1.3.1)
var Configuration-Item : object-class subtype-of syntactic-object
var Block-Configuration : object-class subtype-of configuration-item
var Component-Configuration : object-class subtype-of configuration-item
%% Statements (Chaps. 8 & 9)
var Statement : object-class subtype-of syntactic-object
%% Concurrent Statements (Chap. 9)
var Concurrent-Statement : object-class subtype-of statement
var Labeled-Concurrent-Stmt : object-class subtype-of concurrent-statement
var Unlabeled-Concurrent-Stmt : object-class subtype-of concurrent-statement
var Block-Statement : object-class subtype-of unlabeled-concurrent-stmt
var Process-Statement : object-class subtype-of unlabeled-concurrent-stmt
var Postponed-Concurrent-Stmt : object-class subtype-of unlabeled-concurrent-stmt
var Unpostponed-Concurrent-Stmt : object-class subtype-of unlabeled-concurrent-stmt
var Concurrent-Procedure-Call : object-class subtype-of unpostponed-concurrent-stmt
var Concurrent-Assertion-Stmt : object-class subtype-of unpostponed-concurrent-stmt
var Concurrent-Signal-Assign : object-class subtype-of unpostponed-concurrent-stmt
var Conditional-Signal-Assign : object-class subtype-of concurrent-signal-assign
var Selected-Signal-Assign : object-class subtype-of concurrent-signal-assign
var Component-Instantiation : object-class subtype-of concurrent-statement
var Generate-Statement : object-class subtype-of concurrent-statement
%% Conditional Waveform (Sec. 9.5.1)
var Conditional-Waveform : object-class subtype-of statement
%% Selected Waveform (Sec. 9.5.2)
var Selected-Waveform : object-class subtype-of statement
%% Instantiated Unit (Sec. 9.6)
var Instantiated-Unit : object-class subtype-of statement
var Component-Unit-Name : object-class subtype-of instantiated-unit
var Entity-Unit-Name : object-class subtype-of instantiated-unit
var Configuration-Unit-Name : object-class subtype-of instantiated-unit
%% Generate Statement (Sec. 9.7)
var Generation-Scheme : object-class subtype-of statement
var If-Generation-Scheme : object-class subtype-of generation-scheme
var For-Generation-Scheme : object-class subtype-of generation-scheme
%% Sequential Statements (Chap. 8)
var Sequential-Statement : object-class subtype-of statement
var Labeled-Sequential-Stmt : object-class subtype-of sequential-statement
var Unlabeled-Sequential-Stmt : object-class subtype-of sequential-statement
var Wait-Statement : object-class subtype-of unlabeled-sequential-stmt
var Assertion-Statement : object-class subtype-of unlabeled-sequential-stmt
var Report-Statement : object-class subtype-of unlabeled-sequential-stmt
var Variable-Assignment : object-class subtype-of unlabeled-sequential-stmt
var Signal-Assignment : object-class subtype-of unlabeled-sequential-stmt
var Waveform-Element : object-class subtype-of statement
var Procedure-Call : object-class subtype-of unlabeled-sequential-stmt
var If-Statement : object-class subtype-of unlabeled-sequential-stmt
var Elsif-Object : object-class subtype-of statement
var Case-Statement : object-class subtype-of unlabeled-sequential-stmt
var Case-Alternative : object-class subtype-of statement
var Basic-Loop-Statement : object-class subtype-of unlabeled-sequential-stmt
var While-Loop-Statement : object-class subtype-of unlabeled-sequential-stmt
var For-Loop-Statement : object-class subtype-of unlabeled-sequential-stmt
var Next-Statement : object-class subtype-of unlabeled-sequential-stmt
var Exit-Statement : object-class subtype-of unlabeled-sequential-stmt
var Return-Statement : object-class subtype-of unlabeled-sequential-stmt
var Null-Statement : object-class subtype-of unlabeled-sequential-stmt
%% Target (Sec. 8.4)
var Target : object-class subtype-of statement
%% Delay Mechanism (Sec. 8.4)
var Delay-Mechanism : object-class subtype-of statement
var Transport-Delay-Mechanism : object-class subtype-of delay-mechanism
var Inertial-Delay-Mechanism : object-class subtype-of delay-mechanism
%% Declarations and Specifications (Chaps. 4 & 5)
var Declaration : object-class subtype-of syntactic-object
var Type-Declaration : object-class subtype-of declaration
var Full-Type-Declaration : object-class subtype-of type-declaration
var Incomplete-Type-Declaration : object-class subtype-of type-declaration
var Subtype-Declaration : object-class subtype-of declaration
var Object-Declaration : object-class subtype-of declaration
var Constant-Declaration : object-class subtype-of object-declaration
var Signal-Declaration : object-class subtype-of object-declaration
var Variable-Declaration : object-class subtype-of object-declaration
var File-Declaration : object-class subtype-of object-declaration
var Alias-Declaration : object-class subtype-of declaration
var Attribute-Declaration : object-class subtype-of declaration
var Component-Declaration : object-class subtype-of declaration
var Group-Template-Declaration : object-class subtype-of declaration
var Configuration-Declarative-Item : object-class subtype-of declaration
var Group-Declaration : object-class subtype-of configuration-declarative-item
var Use-Clause : object-class subtype-of configuration-declarative-item
var Attribute-Specification : object-class subtype-of configuration-declarative-item
var Configuration-Specification : object-class subtype-of declaration
var Disconnection-Specification : object-class subtype-of declaration
var Subprogram-Declaration : object-class subtype-of declaration
var Subprogram-Specification : object-class subtype-of subprogram-declaration
var Procedure-Declaration : object-class subtype-of subprogram-specification
var Function-Declaration : object-class subtype-of subprogram-specification
var Pure-Function-Decl : object-class subtype-of function-declaration
var Impure-Function-Decl : object-class subtype-of function-declaration
var Subprogram-Body : object-class subtype-of subprogram-declaration
%% Subprogram Kind (Sec. 2.2)
var Subprogram-Kind : object-class subtype-of syntactic-object
var Procedure-Kind : object-class subtype-of subprogram-kind
var Function-Kind : object-class subtype-of subprogram-kind
%% Various objects used in Declarations
var Entity-Class-Entry : object-class subtype-of syntactic-object
var Component-Specification : object-class subtype-of syntactic-object
var File-Open-Information : object-class subtype-of syntactic-object
var Designator : object-class subtype-of syntactic-object
var Entity-Designator : object-class subtype-of syntactic-object
%% Interface Declarations (Sec. 4.3.2)
var Interface-Declaration : object-class subtype-of syntactic-object
var Interface-File-Decl : object-class subtype-of interface-declaration
%% Binding Indication (Sec. 5.2.1) (Entity, Generic-Map and Port Map Aspects)
var Entity-Aspect : object-class subtype-of syntactic-object
var Generic-Map-Aspect : object-class subtype-of syntactic-object
var Port-Map-Aspect : object-class subtype-of syntactic-object
%% Entity Class (Sec. 5.1)
var Entity-Class : object-class subtype-of syntactic-object
var Entity-Keyword : object-class subtype-of entity-class
var Procedure-Keyword : object-class subtype-of entity-class
var Type-Keyword : object-class subtype-of entity-class
var Signal-Keyword : object-class subtype-of entity-class
var Label-Keyword : object-class subtype-of entity-class
var Group-Keyword : object-class subtype-of entity-class
var Architecture-Keyword : object-class subtype-of entity-class
var Function-Keyword : object-class subtype-of entity-class
var Subtype-Keyword : object-class subtype-of entity-class
var Variable-Keyword : object-class subtype-of entity-class
var Literal-Keyword : object-class subtype-of entity-class
var File-Keyword : object-class subtype-of entity-class
var Configuration-Keyword : object-class subtype-of entity-class
var Package-Keyword : object-class subtype-of entity-class
var Constant-Keyword : object-class subtype-of entity-class
var Component-Keyword : object-class subtype-of entity-class
var Units-Keyword : object-class subtype-of entity-class
%% Entity Header Clauses (Sec. 1.1.1)
var Generic-Clause : object-class subtype-of syntactic-object
var Port-Clause : object-class subtype-of syntactic-object
%% Signal Kind (Sec. 4.3.1.2)
var Signal-Kind : object-class subtype-of syntactic-object
var Register-Kind : object-class subtype-of signal-kind
var Bus-Kind : object-class subtype-of signal-kind
%% Mode (Sec. 4.3.2)
var Mode : object-class subtype-of syntactic-object
var In-Mode : object-class subtype-of mode
var Out-Mode : object-class subtype-of mode
var Inout-Mode : object-class subtype-of mode
var Buffer-Mode : object-class subtype-of mode
var Linkage-Mode : object-class subtype-of mode
%% Types (Sec. 3)
var Type-Definition : object-class subtype-of syntactic-object
var Scalar-Type-Definition : object-class subtype-of type-definition
var Enumeration-Type-Def : object-class subtype-of scalar-type-definition
var Integer-Type-Def : object-class subtype-of scalar-type-definition
var Floating-Type-Def : object-class subtype-of scalar-type-definition
var Physical-Type-Def : object-class subtype-of scalar-type-definition
var Composite-Type-Definition : object-class subtype-of type-definition
var Array-Type-Def : object-class subtype-of composite-type-definition
var Unconstrained-Array-Def : object-class subtype-of array-type-def
var Constrained-Array-Def : object-class subtype-of array-type-def
var Record-Type-Def : object-class subtype-of composite-type-definition
var Access-Type-Definition : object-class subtype-of type-definition
var File-Type-Definition : object-class subtype-of type-definition
%% Physical types (Sec 3.1.3)
var Secondary-Unit-Declaration : object-class subtype-of syntactic-object
var Physical-Literal-Or-Name : object-class subtype-of syntactic-object
%% Array types (Sec 3.2.1)
var Index-Subtype-Definition : object-class subtype-of syntactic-object
%% Record types (Sec 3.2.2)
var Element-Declaration : object-class subtype-of syntactic-object
%% Constraints (Sec. 4.2, 3.1, 3.2.1)
var Range-Constraint : object-class subtype-of syntactic-object
var Index-Constraint : object-class subtype-of syntactic-object
%% NOTE: Any object class with the prefix "Simple-" means that it is the
%% same as the object class of the same name except that anything which
%% could parse as an Expression has been removed.
%% Range (Sec. 3.1, 3.2.1)
var VHDL-Range : object-class subtype-of syntactic-object
var Simple-Range : object-class subtype-of vhdl-range
var Direction : object-class subtype-of syntactic-object
var To-Direction : object-class subtype-of direction
var Downto-Direction : object-class subtype-of direction
%% Discrete Range
var Discrete-Range : object-class subtype-of syntactic-object
var Simple-Discrete-Range : object-class subtype-of syntactic-object
%% Subtype Indications (Sec. 4.2)
var Subtype-Indication : object-class subtype-of syntactic-object
var Simple-Subtype-Indication : object-class subtype-of subtype-indication
%% Signatures (Sec. 2.3.2)
var Signature : object-class subtype-of syntactic-object
%% Expressions (Sec. 7)
var Expression : object-class subtype-of syntactic-object
var Logical-And : object-class subtype-of expression
var Logical-Or : object-class subtype-of expression
var Logical-Xor : object-class subtype-of expression
var Logical-Nand : object-class subtype-of expression
var Logical-Nor : object-class subtype-of expression
var Logical-Xnor : object-class subtype-of expression
var Compare-Equal : object-class subtype-of expression
var Compare-Greater : object-class subtype-of expression
var Compare-Less : object-class subtype-of expression
var Compare-Greater-Equal : object-class subtype-of expression
var Compare-Less-Equal : object-class subtype-of expression
var Compare-Not-Equal : object-class subtype-of expression
var Shift-Left-Logic : object-class subtype-of expression
var Shift-Left-Arith : object-class subtype-of expression
var Shift-Right-Logic : object-class subtype-of expression
var Shift-Right-Arith : object-class subtype-of expression
var Rotate-Left-Logic : object-class subtype-of expression
var Rotate-Right-Logic : object-class subtype-of expression
var Add-Operator-Plus : object-class subtype-of expression
var Add-Operator-Minus : object-class subtype-of expression
var Add-Operator-And : object-class subtype-of expression
var Sign-Operator-Plus : object-class subtype-of expression
var Sign-Operator-Minus : object-class subtype-of expression
var Mult-Operator-Times : object-class subtype-of expression
var Mult-Operator-Divide : object-class subtype-of expression
var Mult-Operator-Mod : object-class subtype-of expression
var Mult-Operator-Rem : object-class subtype-of expression
var Misc-Operator-Square : object-class subtype-of expression
var Misc-Operator-Abs : object-class subtype-of expression
var Misc-Operator-Not : object-class subtype-of expression
var Qualified-Expression : object-class subtype-of expression
var Aggregate-Expression : object-class subtype-of expression
var Allocator : object-class subtype-of expression
%% Association Lists (Sec. 4.3.2.2)
var Association-Element : object-class subtype-of syntactic-object
var Formal-or-Actual-Part : object-class subtype-of syntactic-object
%% Element Associations (Sec. 7.3.2)
var Element-Association : object-class subtype-of syntactic-object
%% Choices (Sec. 7.3.2)
var Choice : object-class subtype-of syntactic-object
%% Names (Sec. 6)
var VHDL-Name : object-class subtype-of syntactic-object
var Simple-Name : object-class subtype-of vhdl-name
var Selected-Name : object-class subtype-of vhdl-name
var Indexed-or-Slice-Name : object-class subtype-of vhdl-name
var Attribute-Name : object-class subtype-of vhdl-name
var Range-Attribute-Name : object-class subtype-of vhdl-name
var String-Literal : object-class subtype-of vhdl-name
%% Identifiers
var Identifier : object-class subtype-of syntactic-object
%% Literals (Sec. 13)
var Literal : object-class subtype-of syntactic-object
var Real-Literal : object-class subtype-of literal
var Integer-Literal : object-class subtype-of literal
var Character-Literal : object-class subtype-of literal
var Bit-String-Literal : object-class subtype-of literal
var Null-Literal : object-class subtype-of literal
var Physical-Literal : object-class subtype-of literal
var Enumeration-Literal : object-class subtype-of syntactic-object
%%%%%%%%%%%%%%%%%%%%%%%%%%%% Design Decisions %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#||
Simply put, some constructs in VHDL fall easily into an object-oriented
description while others just don't. Many choices were made to try and keep this
specification as easy to understand as possible while still remaining true to
the IEEE VHDL '93 Language Reference Manual.
This section contains notes on design decisions which were made. Most of
these design decisions relate to the fact that the VHDL description has many
redundant productions. In other words the same syntax can parse in more than
one way (according to the reference manual). In these cases, semantic information
(such as symbol table info) is needed to determine how the object is to be used.
The order in this section corrseponds to the order in which the VHDL language
specification was written (chronological).
Literals
- In order to distinguish between an identifier
and a physical literal a physical literal was redefined as:
physical_literal ::= abstract_literal <unit>_name
In the case where just a <unit>_name is present, this will be parsed
as an identifier. This will work fine for now but may cause problems
later. (db - 8/30)
- Moved String-Literal so that it is descended from Name instead of
String-Literal. This makes more sense in terms of how objects are
actually used, but makes less sense in terms of how they are named.
Without doing this, a special production would be needed so that
an expression could parse as a String-Literal. (db - 10/3)
Names
- Got rid of Prefix object entirely. The way we are doing function
calls makes a prefix object redundant. (db - 8/30)
- Added object-class Range-Attribute-Name. This is needed because the
reserved word "range" is also the name of a pre-defined attribute. See
notes in Sec. 13.9. (db - 10/4)
Expressions
Function Calls
- A function call and an indexed name are syntactically
pretty much the same thing. The parser dialect generates would not
be able to distinguish between them in most cases, so I have made them
the same thing and defined them both in the object "Indexed-Name".
Whether it is a function call or indexed name will have to be
determined by context (see chap. 10.5). NOTE: also the same as a
type conversion. (db - 9/1)
Association Lists
- Had to re-write association_element as:
association-element ::= [ formal-part-map { [ "=>" actual-part-map ] } ]
In the event that the actual part is not included, the formal part becomes
the actual part (see section 4.3.2.2 LRM). (db - 9/4)
Discrete Range
- Turns out that slice name and indexed name are too similar to differentiate
syntactically. These have been combined into one class Indexed-Or-Slice-Name.
To accomplish this Formal-Or-Actual-Part now goes to a Discrete-Range instead
of just an Expression. This makes things really interesting. (db - 9/9)
- The other really interesting part is that Indexed-Constraint becomes
redundant in a Subtype-Indication since this will be parsed as:
vhdl-name indexed-or-slice-name
(db - 9/9)
- At this point in time I include a tree diagram for discrete-range since
drawing this is about the only way it makes any sense:
Discrete-Range:
discrete-range ________________
/ \ \
simple-subtype- simple-range expression
indication | \ \______
/ | | \ \
name name and/or expression direction expression
constraint
(db - 9/9)
- A Simple-Discrete-Range is the same as Discrete-Range except that
it can not be anything that falls under the class Expression. (db - 9/9)
Realized we don't need Simple-Discrete-Range anymore with the new
Indexed-or-Slice-Name class. Got rid of it, but left this comment
for historical significance.. (db - 9/13)
Range and Range-Constraint
- In the production range ::= <range>_attribute_name |
expression direction expression
<range>_attribute_name was moved up into the object Range-Constraint.
This enabled us to get around one-token lookahead and eliminate the
conflicts caused between Expression and Attribute-Name. (db - 9/13)
- Note also that Index-Constraint and Range-Constraint are completely
separate objects. No relation! This is as it should be and not as
the VHDL LRM would lead you to think. (db - 9/13)
Declarations
Group Declaration
- A group declaration containing a group_constituent_list is the
same as the <group_template>_name being an indexed-or-slice-name.
(db - 9/16)
Entity Aspect
- An entity aspect with an <architecture>_identifier is the same as
having the <entity>_name being an indexed-or-slice-name.
(db - 9/16)
Concurrent Statements
Conditional Signal Assignment
- Wrote this a little differently then the reference manual suggests.
Either a semantic check to make sure that Conditional-Waveform contains
a test-condition everywhere but in the last statement is needed or this
needs to be re-written. (db - 9/25)
Component Instantiation
- Component instantiation is correct except for one special case.
This special case occurs when an component instantiation is of the
form:
component_instantiation ::= [ <instantiation>_label ":"
<component>_name ]
In this special case, our object model calls this a concurrent-procedure-call
object and not a component instantiation. A semantic check will need to be
performed on concurrent-procedure-call to make sure it is not a
component-instantiation. (db - 9/29)
Instantiated Unit
- An instantiated unit of the form:
instantiated_unit ::= "entity" <entity>_name [ "(" <architecture>_identifier ")" ]
is represented in our model as:
entity-unit-name
::= [ "entity" instantiated-unit-name ]
builds entity-unit-name
The instantiation-unit-name will be an indexed-or-slice-name if there is an
optional <architecture>_identifier. (db - 10/7)
Configuration Declaration
- Configuration-Declaration has a declaration section. Unfortunately, due
to the parser inability to distiguish between a Block-Configuration and a
Configuration-Specification we could not use the attribute DECLARATION-LIST.
So evolved the creation of the object Configuration-Declarative-Item. This
object merely allows the parsing of:
Use-Clause | Attribute-Specification | Group-Declaration
||#
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Notes %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
#||
This section contains a list of the things remaining to be fixed. As they
are fixed please delete them from here.
Expressions
- Aggregate expression. Problem with the added production
expression ::= "(" expression ")"
Might want to solve this by forcing an aggregate to have more than
one element-associations. Or maybe not. (db - 9/22)
Seems like any fix I can see is worse than the problem. As things
stand now the parser correctly chooses the shift so I'm leaving it alone.
(db - 9/29)
||#
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