1. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU1 Language Attributes and Package Standard A very useful aspect of the language.

2. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU2 Attributes  What are attributes?  VHDL Attributes Types Signal Variables Examples Signal Specific Other  Package Standard

3. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU3 What are attributes?  John is just plain nasty!!!! Being nasty is an attribute of John.  Language attributes Lovely, pretty and handsome are adjectives which describe and a attribute of the language element they apply to.  Lovely Rita ….. (Do you remember the Beatles!)

4. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU4 What are attributes?  VHDL attributes provide additional information on the language element to which they are associated.  For example They can tell you the size of an array and whether the index is X to Y or Y downto X. They can tell you a signal’s last value Etc.

5. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU5 Attributes that relate to TYPES  ATTRIBUTE: T’BASE Kind: Type Prefix: Any Type or Subtype T Result Type: The base type of T Result: Same – a type Restrictions: This attribute is allowed only as a prefix of the name of another attribute; T’BASE’LEFT Example: BIT’BASE’LEFT is ‘0’  Base Type: The base type of a type is the type itself

6. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU6 Attributes that relate to TYPES  ATTRIBUTE: T’LEFT Kind: Value Prefix: Any scalar type or subtype T Result Type: Same type a T Result: The left bound of T Example: BIT’LEFT has value ‘0’ Scalar type consist of enumeration, integer, physical, and floating point types.

7. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU7 Attributes that relate to TYPES  ATTRIBUTE: T’RIGHT Kind: Value Prefix: Any scalar type or subtype T Result Type: Same type a T Result: The right bound of T Example: BIT’RIGHT has value ‘1’

8. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU8 Attributes that relate to TYPES  ATTRIBUTE: T’HIGH Kind: Value Prefix: Any scalar type or subtype T Result Type: Same type a T Result: The upper bound of T Example: BIT’ HIGH has value ‘1’

9. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU9 Attributes that relate to TYPES  ATTRIBUTE: T’LOW Kind: Value Prefix: Any scalar type or subtype T Result Type: Same type a T Result: The lower bound of T Example: BIT’LOW has value ‘0’

10. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU10 Attributes that relate to TYPES  ATTRIBUTE: T’POS(X) Kind: Function Prefix: Any discrete or physical type or subtype T  A discrete type is an enumeration or intger type. Parameter: Any expression whose type is the base type of T Result Type: Universal Integer  Universal integer is an integer of an anonymous predefined integer type. An integer. Result: The position number of the value of the parameter. Example:  type operations is (OPADD, OPSUB, OPAND, OPOR);  signal oper : operations;  Then operations’POS(OPSUB) has value 2  operations’POS(OPOR) has value 4

11. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU11 Attributes that relate to TYPES  ATTRIBUTE: T’VAL(X) Kind: Function Prefix: Any discrete or physical type or subtype T Parameter: Any expression of any integer type Result Type: The base type of T Result: The value from the type whose position number is the universal integer value corresponding to X Example:  type operations is (OPADD, OPSUB, OPAND, OPOR);  signal oper : operations;  Then operations’VAL(2) has value OPSUB  operations’VAL(4) has value OPOR

12. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU12 Attributes that relate to TYPES  ATTRIBUTE: T’SUCC(X) Kind: Function Prefix: Any discrete or physical type or subtype T Parameter: Any expression whose type is the base type of T Result Type: The base type of T Result: The value whose position number is one greater than that of the parameter. Restricitons: An error occurs if X equals T’BASE’HIGH Example:  type operations is (OPADD, OPSUB, OPAND, OPOR);  signal oper : operations;  Then operations’SUCC(OPSUB) has value OPAND  operations’SUCC(OPAND) has value OPOR

13. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU13 Attributes that relate to TYPES  ATTRIBUTE: T’PRED(X) Kind: Function Prefix: Any discrete or physical type or subtype T Parameter: Any expression whose type is the base type of T Result Type: The base type of T Result: The value whose position number is one less than that of the parameter. Restricitons: An error occurs if X equals T’BASE’LOW Example:  type operations is (OPADD, OPSUB, OPAND, OPOR);  signal oper : operations;  Then operations’PRED(OPSUB) has value OPADD  operations’PRED(OPAND) has value OPSUB

14. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU14 Attributes that relate to TYPES  ATTRIBUTE: T’LEFTOF(X) Kind: Function Prefix: Any discrete or physical type or subtype T Parameter: Any expression whose type is the base type of T Result Type: The base type of T Result: The value which is to the left of the parameter in the range of T. Restricitons: An error occurs if X equals T’BASE’LEFT Example:  type operations is (OPADD, OPSUB, OPAND, OPOR);  signal oper : operations;  Then operations’LEFTOF(OPSUB) has value OPADD

15. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU15 Attributes that relate to TYPES  ATTRIBUTE: T’RIGHTOF(X) Kind: Function Prefix: Any discrete or physical type or subtype T Parameter: Any expression whose type is the base type of T Result Type: The base type of T Result: The value which is to the right of the parameter in the range of T. Restricitons: An error occurs if X equals T’BASE’RIGHT Example:  type operations is (OPADD, OPSUB, OPAND, OPOR);  signal oper : operations;  Then operations’RIGHTOF(OPSUB) has value OPAND

16. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU16 Attributes that relate to ARRAYS  ATTRIBUTE: A’LEFT[(N)] Kind: Function Prefix: Any prefix A that is an array object Parameter: Locally static expression of type integer. Defaults to 1. Result Type: Type of the Nth index range of A Result: Left bound of the Nth index range of A.  ATTRIBUTE: A’RIGHT[(N)] Kind: Function Prefix: Any prefix A that is an array object Parameter: Locally static expression of type integer. Defaults to 1. Result Type: Type of the Nth index range of A Result: Right bound of the Nth index range of A.

17. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU17 Attributes that relate to ARRAYS  ATTRIBUTE: A’HIGH[(N)] Kind: Function Prefix: Any prefix A that is an array object Parameter: Locally static expression of type integer. Defaults to 1. Result Type: Type of the Nth index range of A Result: Upper bound of the Nth index range of A.  ATTRIBUTE: A’LOW[(N)] Kind: Function Prefix: Any prefix A that is an array object Parameter: Locally static expression of type integer. Defaults to 1. Result Type: Type of the Nth index range of A Result: Lower bound of the Nth index range of A.

18. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU18 Attributes that relate to ARRAYS  ATTRIBUTE: A’RANGE[(N)] Kind: Range Prefix: Any prefix A that is an array object Parameter: Locally static expression of type integer. Defaults to 1. Result Type: Type of the Nth index range of A Result: The range A’LEFT(N) to A’RIGHT(N) or A’LEFT(N) downto A’RIGHT(N)  ATTRIBUTE: A’REVERSE_RANGE[(N)] Kind: Range Prefix: Any prefix A that is an array object Parameter: Locally static expression of type integer. Defaults to 1. Result Type: Type of the Nth index range of A Result:. The range A’ RIGHT(N) to A’ LEFT(N) or A’ RIGHT(N) downto A’ LEFT(N)

19. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU19 Attributes that relate to ARRAYS  ATTRIBUTE: A’LENGHT[(N)] Kind: Range Prefix: Any prefix A that is an array object Parameter: Locally static expression of type integer. Defaults to 1. Result Type: Universal Integer Result: Number of values in the Nth index range, i.e., A’HIGH(N) – A’LOW(N) +1

20. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU20 Attributes that relate to ARRAYS  EXAMPLE: signal mydt : bit_vector (31 downto 0); signal myto : bit_vector ( 0 to 15);  Then the

21. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU21 Attributes that relate to ARRAYS  EXAMPLE: signal mydt : bit_vector (31 downto 0); signal myto : bit_vector ( 0 to 15);  Then the

22. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU22 Attributes that relate to ARRAYS  EXAMPLE: signal mydt : bit_vector (31 downto 0); signal myto : bit_vector ( 0 to 15);  Then the

23. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU23 Attributes that relate to ARRAYS  EXAMPLE: signal mydt : bit_vector (31 downto 0); signal myto : bit_vector ( 0 to 15);  Then the

24. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU24 Attributes that relate to ARRAYS  EXAMPLE: signal mydt : bit_vector (31 downto 0); signal myto : bit_vector ( 0 to 15);  Then the

25. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU25 Attributes that relate to ARRAYS  EXAMPLE: signal mydt : bit_vector (31 downto 0); signal myto : bit_vector ( 0 to 15);  Then the

26. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU26 Attributes that relate to ARRAYS  EXAMPLE: signal mydt : bit_vector (31 downto 0); signal myto : bit_vector ( 0 to 15);  Then the

27. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU27 Attributes that relate to ARRAYS  EXAMPLE: signal mydt : bit_vector (31 downto 0); signal myto : bit_vector ( 0 to 15);  Then the

28. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU28 Attributes that relate to SIGNALS  ATTRIBUTE: S’DELAYED[(T)] Kind: Signal Prefix: Any signal Parameter: Any static expression of type TIME that evaluates to a non-negative value. Result Type: Base type of S Result: A signal equivalent to S delayed T units of time. The value of S’DELAYED(t) is always equal to the value of S t units of time previous.

29. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU29 Attributes that relate to SIGNALS  ATTRIBUTE: S’STABLE[(T)] Kind: Signal Prefix: Any signal Parameter: Any static expression of type TIME that evaluates to a non-negative value. Defaults to 0 if omitted. Result Type: Boolean Result: A signal that has value TRUE when an event has not occurred on signal S for T units of time, and the value FALSE otherwise.

30. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU30 Attributes that relate to SIGNALS  ATTRIBUTE: S’QUIET[(T)] Kind: Signal Prefix: Any signal Parameter: Any static expression of type TIME that evaluates to a non-negative value. Defaults to 0 if omitted. Result Type: Boolean Result: A signal that has value TRUE when the signal has been quiet (not had a change in value) for T units of time.

31. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU31 Attributes that relate to SIGNALS  ATTRIBUTE: S’TRANSACTION Kind: Signal Prefix: Any signal Result Type: Type BIT Result: A signal that toggles to the inverse of its previous value in each simulation cycle in which the signal S becomes active.  ATTRIBUTE: S’EVENT Kind: Signal Prefix: Any signal Result Type: Type BOOLEAN Result: A value that indicates whether an event has just occurred on signal S.

32. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU32 Attributes that relate to SIGNALS  ATTRIBUTE: S’ACTIVE Kind: Function Prefix: Any signal Result Type: Type BOOLEAN Result: A value that indicated whether S is active, i.e., has a new value generated for it this simulation cycle.  ATTRIBUTE: S’LAST_EVENT Kind: Function Prefix: Any signal Result Type: Type TIME Result: The amount of time that has elapsed since the last event on signal S.

33. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU33 Attributes that relate to SIGNALS  ATTRIBUTE: S’LAST_ACTIVE Kind: Function Prefix: Any signal Result Type: Type TIME Result: The amount of time that has elapsed since the last time the signal S was active.  ATTRIBUTE: S’LAST_VALUE Kind: Function Prefix: Any signal Result Type: Base type of S Result: The previous value of S.

34. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU34 Attributes that relate to Design Units  ATTRIBUTE: B’BEHAVIOR Kind: Value Prefix: Any block denoted by a label or entity denoted by its architecture name. Result Type: BOOLEAN Result: The value if TRUE if the block defined by the block statement or entity does not contain a component instantiation statement.  ATTRIBUTE: B’STRUCTURE The same except that TRUE when the block/entity contains only component instantiations

35. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU35 Package STANDARD

36. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU36 Package Standard (cont.)

37. 1/8/2007 - L10 AttributesCopyright 2006 - Joanne DeGroat, ECE, OSU37 Package Standard (completed)