VHDL Glossary | |
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| There are 19 entries in the glossary. | |
| Pages: 1 | |
| Term | Definition |
| Effective value | The value obtained by evaluating a reference to the signal within an expression. |
| Elaboration | The process by which a declaration achieves its effect. Prior to the completion of its elaboration (including before the elaboration), a declaration is not yet elaborated. |
| Element | A constituent of a composite type. |
| Entity declaration |
A definition of the interface between a given design entity and the environment in which it is used. It may also specify declarations and statements that are part of the design entity. A given entity declaration may be shared by many design entities, each of which has a different architecture. Thus, an entity declaration can potentially represent a class of design entities, each with the same interface.
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| Enumeration literal | A literal of an enumeration type. An enumeration literal is either an identifier or a character literal. |
| Enumeration type | A type whose values are defined by listing (enumerating) them. The values of the type are represented by enumeration literals. |
| Erroneous | An error condition that cannot always be detected. |
| Error | A condition that makes the source description illegal. If an error is detected at the time of analysis of a design unit, it prevents the creation of a library unit for the given design unit. A run-time error causes simulation to terminate. |
| Event | A change in the current value of a signal, which occurs when the signal is updated with its effective value. |
| Execute |
(A) When first the design hierarchy of a model is elaborated, then its nets are initialized, and finally simulation proceeds with repetitive execution of the simulation cycle, during which processes are executed and nets are updated.
(B) When a process performs the actions specified by the algorithm described in its statement part. |
| Expanded name | A selected name (in the syntactic sense) that denotes one or all of the primary units in a library or any named entity within a primary unit. |
| Explicit ancestor |
The parent of the implicit signal that is defined by the predefined attributes 'DELAYED, 'QUIET, 'STABLE, or 'TRANSACTION. It is determined using the prefix of the attribute. If the prefix denotes an explicit signal or a slice or subelement (or member thereof), then that is the explicit ancestor of the implicit signal. If the prefix is one of the implicit signals defined by the predefined attributes 'DELAYED, 'QUIET, 'STABLE, or 'TRANSACTION, this rule is applied recursively. If the prefix is an implicit signal GUARD, the signal has no explicit ancestor.
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| Explicit signal |
A signal, other than those defined by the predefined attributes 'DELAYED, 'QUIET, 'STABLE, or 'TRANSACTION, any implicit signal GUARD, or their slices, subelements, or slices of their subelements. A slice, subelement, or a slice of a subelement of an explicit signal is also an explicit signal.
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| Explicitly declared constant | A constant of a specified type that is declared by a constant declaration. |
| Explicitly declared object |
An object of a specified type that is declared by an object declaration. An object declaration is called a single-object declaration if its identifier list has a single identifier; it is called a multiple-object declaration if the identifier list has two or more identifiers.
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| Expression | A formula that defines the computation of a value. |
| Extend |
A property of source text forming a declarative region with disjoint parts. In a declarative region with disjoint parts, if a portion of text is said to extend from some specific point of a declarative region to the end of the region, then this portion is the corresponding subset of the declarative region (and does not include intermediate declarative items between an interface declaration and a corresponding body declaration).
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| Extended digit | A lexical element that is either a digit or a letter. |
| External block | A top-level design entity that resides in a library and may be used as a component in other designs. |
| Glossary & Definitions | |