1076_axb.html

basic exemple. Do an ADD of two 4 bits numbers

<p>c)  A selected name, an indexed name, or a slice name;  
<p>d)  A qualification (in a qualified expression), an explicit type conversion, a formal or actual designator in the form of a type conversion, or an implicit type conversion of a value of type <i>universal_integer</i> or <i>universal_real</i> to the corresponding value of another numeric type;  or 
<p>e)  A numeric literal (for a universal type), the literal null (for an access type), a string literal, a bit string literal, an aggregate, or a predefined attribute.  (<a name="1076_3.html#3">&#167;3</a>)
</ul>
<p><b>B.29 basic signal:</b>  A signal that determines the driving values for all other signals.  A basic signal is
<ul>
<p>--  Either a scalar signal or a resolved signal;
<p>--  Not a subelement of a resolved signal;
<p>--  Not an implicit signal of the form S'Stable(T), S'Quiet(T), or S'Transaction; and
<p>--  Not an implicit signal GUARD.  (&#167;  <a href = "1076_12.HTM#12.6.2"> 12.6.2 </a>  )
</ul>
<p><b>B.30 belong</b> (to a range):<b> </b>A property of a value with respect to some range. The value V is said to <i>belong to</i> <i>a range</i> if the relations (lower bound &lt;= V) and (V &lt;= upper bound) are both true,where lower bound and upper bound are the lower and upper bounds, respectively,of the range.  (<i>&#167;</i><i>  <a href = "1076_3.HTM#3.1"> 3.1 </a>  </i>, &#167;  <a href = "1076_3.HTM#3.2.1"> 3.2.1 </a>  )
<p><b>B. 31 belong</b> (to a subtype):  A property of a value with respect to some subtype.  A value is said to <i>belong to</i> <i>a subtype</i> of a given type if it belongs to the type and satisfies the applicable constraint.(<i>&#167;</i><i>3</i>, &#167;  <a href = "1076_3.HTM#3.2.1"> 3.2.1 </a>  )
<p><b>B.32 binding:</b>  The process of associating a design entity and,optionally, an architecture with an instance of a component.  A binding can be specified in an explicit or a default binding indication.  (&#167;  <a href = "1076_1.HTM#1.3"> 1.3 </a>  , <i></i><i>&#167;</i>  <a href = "1076_5.HTM#5.2.1"> 5.2.1 </a>  <i>, </i>&#167;  <a href = "1076_5.HTM#5.2.2"> 5.2.2 </a>  <i>,</i> &#167;<b>  <a href = "1076_12.HTM#12.3.2.2"> 12.3.2.2 </a>  </b>, &#167;  <a href = "1076_12.HTM#12.4.3"> 12.4.3 </a>  )
<p><b>B.33 bit string literal: </b> A literal formed by a sequence of extended digits enclosed between two quotation (") characters and preceded by a base specifier.  The type of a bit string literal is determined from the context.(&#167;  <a href = "1076_7.HTM#7.3.1"> 7.3.1 </a>  , <i></i><i>&#167;</i>  <a href = "1076_13.HTM#13.7"> 13.7 </a>  <i>)</i>
<p><b>B. 34 block:  </b>The representation of a portion of the hierarchy of a design.  A block is either an external block or an internal block.(<i>&#167;</i><i>1</i>, &#167;  <a href = "1076_1.HTM#1.1.1.1"> 1.1.1.1 </a>  , &#167;  <a href = "1076_1.HTM#1.1.1.2"> 1.1.1.2 </a>  , &#167;  <a href = "1076_1.HTM#1.2.1"> 1.2.1 </a>   &#167;  <a href = "1076_1.HTM#1.3"> 1.3 </a>  , <i>&#167;</i><i>  <a href = "1076_1.HTM#1.3.1"> 1.3.1 </a>  </i>, &#167;  <a href = "1076_1.HTM#1.3.2"> 1.3.2 </a>  )
<p><b>B.35 bound: </b>A label that is identified in the instantiation list of a configuration specification.  (&#167;  <a href = "1076_5.HTM#5.2"> 5.2 </a>  )
<p><b>B.36 box:</b>  The symbol &lt;> in an index subtype definition, which stands for an undefined range.  Different objects of the type need not have the same bounds and direction.  (&#167;  <a href = "1076_3.HTM#3.2.1"> 3.2.1 </a>  )
<p><b>B.37 bus: </b> One kind of guarded signal.  A bus floats to a user-specified value when all of its drivers are turned off.  (&#167;  <a href = "1076_4.HTM#4.3.1.2"> 4.3.1.2 </a>  , &#167;  <a href = "1076_4.HTM#4.3.2"> 4.3.2 </a>  )
<p><b>B.38 character literal:</b>  A literal of the character type.  Character literals are formed by enclosing one of the graphic characters (including the space and nonbreaking space characters) between two apostrophe (') characters.(&#167;  <a href = "1076_13.HTM#13.2"> 13.2 </a>  , <i></i><i>&#167;</i><i>  <a href = "1076_13.HTM#13.5"> 13.5 </a>  </i><i>)</i>
<p><b>B.39 character type:</b>  An enumeration type with at least one character literal among its enumeration literals.  (<i></i><i>&#167;</i>  <a href = "1076_3.HTM#3.1.1"> 3.1.1 </a>  <i>, </i>&#167;  <a href = "1076_3.HTM#3.1.1.1"> 3.1.1.1 </a>  )
<p><b>B.40 closely related types:</b>  Two type marks that denote the same type or two numeric types.  Two array types may also be closely related if they have the same dimensionality, if their index types at each position are closely related, and if the array types have the same element types.  Explicit type conversion is only allowed between closely related types.  (&#167;  <a href = "1076_7.HTM#7.3.5"> 7.3.5 </a>  )
<p><b>B.41 complete: </b> A loop that has finished executing.  Similarly, an iteration scheme of a loop is complete when the condition of a while iteration scheme is FALSE or all of the values of the discrete range of a for iteration scheme have been assigned to the iteration parameter.  (&#167;  <a href = "1076_8.HTM#8.9"> 8.9 </a>  )
<p><b>B.42 complete context: </b>A declaration, a specification, or a statement; complete contexts are used in overload resolution.  (&#167;  <a href = "1076_10.HTM#10.5"> 10.5 </a>  )
<p><b>B.43 composite type:</b>  A type whose values have elements.  There are two classes of composite types: <i>array types</i> and <i>record types</i>.(&#167;3, &#167;<i>  <a href = "1076_3.HTM#3.2"> 3.2 </a>  </i>)
<p><b>B.44 concurrent statement: </b> A statement that executes asynchronously,with no defined relative order.  Concurrent statements are used for dataflow and structural descriptions.  (&#167;9)
<p><b>B.45 configuration: </b> A construct that defines how component instances in a given block are bound to design entities in order to describe how design entities are put together to form a complete design.  (<i>&#167;</i>1, &#167;  <a href = "1076_1.HTM#1.3"> 1.3 </a>  , &#167;  <a href = "1076_5.HTM#5.2"> 5.2 </a>  )
<p><b>B.46 conform:</b>  Two subprogram specifications, are said to conform if, apart from certain allowed minor variations, both specifications are formed by the same sequence of lexical elements, and corresponding lexical elements are given the same meaning by the visibility rules.  Conformance is defined similarly for deferred constant declarations.  (&#167;  <a href = "1076_2.HTM#2.7"> 2.7 </a>  )
<p><b>B.47 connected:</b>  A formal port associated with an actual port or signal.  A formal port associated with the reserved word <b>open</b> is said to be <i>unconnected</i>.  (&#167;  <a href = "1076_1.HTM#1.1.1.2"> 1.1.1.2 </a>  )
<p><b>B.48 constant:</b>  An object whose value may not be changed.  Constants maybe <i>explicitly declared</i>, subelements of explicitly declared constants, or interface constants.  Constants declared in packages may also be  <i>deferred constants</i>.  (&#167;  <a href = "1076_4.HTM#4.3.1.1"> 4.3.1.1 </a>  )
<p><b>B.49 constraint:</b>  A subset of the values of a type.  The set of possible values for an object of a given type that can be subjected to a condition is called a <i>constraint</i>.  A value is said to <i>satisfy</i> the constraint if it satisfies the corresponding condition.  There are index constraints,range constraints, and size constraints.  (&#167;3)
<p><b>B.50 conversion function:</b>  A function used to convert values flowing through associations.  For interface objects of mode <b>in</b>, conversion functions are allowed only on actuals.  For interface objects of mode <b>out</b> or<b> buffer</b>, conversion functions are allowed only on formals.  For interface objects of mode <b>inout </b>or<b> linkage</b>, conversion functions are allowed on both formals and actuals.  Conversion functions have a single parameter.  A conversion function associated with an actual accepts the type of the actual and returns the type of the formal.  A conversion function associated with a formal accepts the type of the formal and returns the type of the actual.  (&#167;  <a href = "1076_4.HTM#4.3.2.2"> 4.3.2.2 </a>  )
<p><b>B.51 convertible:</b>  A property of an operand with respect to some type.  An operand is convertible to some type if there exists an implicit conversion to that type.  (&#167;  <a href = "1076_7.HTM#7.3.5"> 7.3.5 </a>  )
<p><b>B.52 current value:</b>  The value component of the single transaction of a driver whose time component is not greater than the current simulation time.(&#167;  <a href = "1076_12.HTM#12.6"> 12.6 </a>  , <i>&#167;</i>  <a href = "1076_12.HTM#12.6.1"> 12.6.1 </a>  , &#167;  <a href = "1076_12.HTM#12.6.2"> 12.6.2 </a>  , &#167;  <a href = "1076_12.HTM#12.6.3"> 12.6.3 </a>  )
<p><b>B.53 decimal literal:</b>  An abstract literal that is expressed in decimal notation.  The base of the literal is implicitly 10.  The literal may optionally contain an exponent or a decimal point and fractional part.(&#167;  <a href = "1076_13.HTM#13.4.1"> 13.4.1 </a>  )
<p><b>B.54 declaration:</b>  A construct that defines a declared entity and associates an identifier (or some other notation) with it.  This association is in effect within a region of text that is called the <i>scope</i> of the declaration.  Within the scope of a declaration, there are places where it is possible to use the identifier to refer to the associated declared entity; at such places, the identifier is said to be the <i>simple name</i> of the named entity.  The simple name is said to <i>denote</i> the associated named entity.(&#167;4)
<p><b>B.55 declarative part:</b>  A syntactic component of certain declarations or statements (such as entity declarations, architecture bodies, and block statements).  The declarative part defines the lexical area (usually introduced by a keyword such as <b>is</b> and terminated with another keyword such as <b>begin</b>) within which declarations may occur.  (<i>&#167;</i>  <a href = "1076_1.HTM#1.1.2"> 1.1.2 </a>  , <i>&#167;</i>  <a href = "1076_1.HTM#1.2.1"> 1.2.1 </a>  , &#167;  <a href = "1076_1.HTM#1.3"> 1.3 </a>  , &#167;  <a href = "1076_2.HTM#2.6"> 2.6 </a>  , &#167;  <a href = "1076_9.HTM#9.1"> 9.1 </a>  , &#167;  <a href = "1076_9.HTM#9.2"> 9.2 </a>  , &#167;  <a href = "1076_9.HTM#9.6.1"> 9.6.1 </a>  , &#167;  <a href = "1076_9.HTM#9.6.2"> 9.6.2 </a>  )
<p><b>B.56 declarative region:</b>  A semantic component of certain declarations or statements.  A declarative region may include disjoint parts, such as the declarative region of an entity declaration, which extends to the end of any architecture body for that entity.  (&#167;  <a href = "1076_10.HTM#10.1"> 10.1 </a>  )
<p><b>B.57 decorate: </b> To associate a user-defined attribute with a named entity and to define the value of that attribute.  (&#167;  <a href = "1076_5.HTM#5.1"> 5.1 </a>  )
<p><b>B.58 default expression:</b>  A default value that is used for a formal generic, port, or parameter if the interface object is unassociated.  A default expression is also used to provide an initial value for signals and their drivers.  (<i>&#167;</i><i>  <a href = "1076_4.HTM#4.3.1.2"> 4.3.1.2 </a>  </i>, <i>&#167;</i><i>  <a href = "1076_4.HTM#4.3.2.2"> 4.3.2.2 </a>  </i>)
<p><b>B.59 deferred constant:</b>  A constant that is declared without an assignment symbol (:=) and expression in a package declaration.  A corresponding full declaration of the constant must exist in the package body to define the value of the constant.  (&#167;  <a href = "1076_4.HTM#4.3.1.1"> 4.3.1.1 </a>  )
<p><b>B.60 delta cycle:</b>  A simulation cycle in which the simulation time at the beginning of the cycle is the same as at the end of the cycle.  That is,simulation time is not advanced in a delta cycle.  Only nonpostponed processes can be executed during a delta cycle.  (&#167;  <a href = "1076_12.HTM#12.6.4"> 12.6.4 </a>  )
<p><b>B.61 denote:</b>  A property of the identifier given in a declaration.  Where the declaration is visible, the identifier given in the declaration is said to <i>denote</i> the named entity declared in the declaration.(&#167;4)
<p><b>B.62 depend </b>(on a library unit): A design unit that explicitly or implicitly mentions other library units in a use clause.  These dependencies affect the allowed order of analysis of design units.  (&#167;  <a href = "1076_11.HTM#11.4"> 11.4 </a>  )
<p><b>B.63 depend </b>(on a signal value):<b> </b> A property of an implicit signal with respect to some other signal.  The current value of an implicit signal R is said to <i>depend on</i> the current value of another signal S if R denotes an implicit signal S'Stable(T), S'Quiet(T), or S'Transaction, or if R denotes an implicit GUARD signal and S is any other implicit signal named within the guard expression that defines the current value of R.(&#167;  <a href = "1076_12.HTM#12.6.3"> 12.6.3 </a>  )
<p><b>B.64 descending range:</b>  A range L <b>downto</b> R.  (&#167;  <a href = "1076_3.HTM#3.1"> 3.1 </a>  )
<p><b>B.65 design entity:</b>  An entity declaration together with an associated architecture body.  Different design entities may share the same entity declaration, thus describing different components with the same interface or different views of the same component.  (&#167;1)
<p><b>B.66 design file: </b>One or more design units in sequence.  (&#167;  <a href = "1076_11.HTM#11.1"> 11.1 </a>  )
<p><b>B.67 design hierarchy:</b>  The complete representation of a design that results from the successive decomposition of a design entity into subcomponents and binding of those components to other design entities that may be decomposed in a similar manner.  (&#167;1)
<p><b>B.68 design library:</b>  A host-dependent storage facility for intermediate-form representations of analyzed design units.  (&#167;  <a href = "1076_11.HTM#11.2"> 11.2 </a>  )
<p><b>B.69 design unit:</b>  A construct that can be independently analyzed and stored in a design library.  A design unit may be an entity declaration, an architecture  body, a configuration declaration, a package declaration, or a package body declaration.  (&#167;  <a href = "1076_11.HTM#11.1"> 11.1 </a>  )