VHDL Programming

442 Appendix B: VHDL Reference Tables Table B-4 Attribute Explanation Example S’DELAYED(T) Creates a new signal delayed by T clo ...

Appendix B: VHDL Reference Tables 443 Table B-6 Literal Type Example Decimal Integer 52 0 3E3 --equals 3000 1_000_000 --equals 1 ...

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Appendix C Reading VHDL BNF After the basic concepts of VHDL are understood, the designer might want to try to write VHDL in a m ...

Statements enclosed in curly braces { }, as in lines 4 and 5, are optional and repeatable constructs. An optional and repeatable ...

boolean expression construct to describe the syntax required, none will be found. The reason is that all expressions share the s ...

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Appendix D VHDL93 Updates Early in 1993 the VHDL language standard was updated to reflect a number of shortcomings with the VHDL ...

Not only can objects be aliased in VHDL93 but functions can as well. To specify a function aliasrequires a subprogram signature ...

the resolved value that a particular driver is driving so that it can be further used in the model. In the example shown here th ...

452 Appendix D: VHDL93 Updates `INSTANCE_NAME—returns a string that describes the path to the entity starting at the root of th ...

and bound to an entity with a configuration. The component could have been directly or implicitly configured. In VHDL93 entities ...

In this example the entity name (\74ls163\), and one of the input ports (\1n1\) are extended identifiers. File Operations One of ...

An alternate way of opening the file without calling the explicit FILE_OPENprocedure is similar to the method used in VHDL87. Th ...

called FOREIGNwhose value is a string. This string value describes the interface to the external function, procedure, or entity. ...

u1: mux4 PORT MAP( k0 => s0, k1 => s1, k2 => s2, en => ‘ 1 ’, q => outp); In the example above the value 1 is map ...

These attributes act on both signals in the group. Another way to describe a group, especially a group that varies in size, is s ...

BEGIN -- .. -- .. d1 : dff PORT MAP( z, clock, qout); END ARCHITECTURE struct; CONFIGURATION topcon OF top IS FOR struct FOR d1 ...

The keyword POSTPONEDis specified before the PROCESSkeyword to specify a postponed process. Pure and Impure Functions Functions ...

the inertial delayspecified. In some cases this is too pessimistic. In VHDL93 the modeler has the ability to specify a pulse rej ...