VHDL Predefined Attributes

 

VHDL Predefined Attributes

 

 

T'BASE                     is the base type of the type T

T'LEFT                     is the leftmost value of type T. (Largest if downto)

T'RIGHT                  is the rightmost value of type T. (Smallest if downto)

T'HIGH                     is the highest value of type T.

T'LOW                     is the lowest value of type T.

T'ASCENDING        is boolean true if range of T defined with to .

 T'IMAGE(X)           is a string representation of X that is of type T.

T'VALUE(X)             is a value of type T converted from the string X.

T'POS(X)                  is the integer position of X in the discrete type T.

T'VAL(X)                 is the value of discrete type T at integer position X.

T'SUCC(X)               is the value of discrete type T that is the successor of X.

T'PRED(X)                is the value of discrete type T that is the predecessor of X.

T'LEFTOF(X)            is the value of discrete type T that is left of X.

T'RIGHTOF(X)         is the value of discrete type T that is right of X.

A'LEFT                      is the leftmost subscript of array A or constrained array type.

A'LEFT(N)                  is the leftmost subscript of dimension N of array A.

A'RIGHT                    is the rightmost subscript of array A or constrained array type.

A'RIGHT(N)              is the rightmost subscript of dimension N of array A.

A'HIGH                       is the highest subscript of array A or constrained array type.

A'HIGH(N)                 is the highest subscript of dimension N of array A.

A'LOW                       is the lowest subscript of array A or constrained array type.

A'LOW(N)                 is the lowest subscript of dimension N of array A.

 

A'RANGE                  is the range A'LEFT to A'RIGHT or A'LEFT downto A'RIGHT .

A'RANGE(N)             is the range of dimension N of A.
 

A'REVERSE_RANGE    is the range of A with to and downto reversed.

A'REVERSE_RANGE(N)     is the REVERSE_RANGE of dimension N of array A.

A'LENGTH                             is the integer value of the number of elements in array A.

A'LENGTH(N)                        is the number of elements of dimension N of array A.

 

A'ASCENDING                       is boolean true if range of A defined with to .

A'ASCENDING(N)                 is boolean true if dimension N of array A defined with to .

S'DELAYED(t)                        is the signal value of S at time now - t .

S'STABLE                                is true if no event is occurring on signal S.

S'STABLE(t)                             is true if no even has occurred on signal S for t units of time.

S'QUIET                                     is true if signal S is quiet. (no event this simulation cycle)

S'QUIET(t)                                is true if signal S has been quiet for t units of time.

S'TRANSACTION                     is a bit signal, the inverse of previous value each cycle S is active.

S'EVENT                                   is true if signal S has had an event this simulation cycle.

S'ACTIVE                                   is true if signal S is active during current simulation cycle.

S'LAST_EVENT                      is the time since the last event on signal S.

S'LAST_ACTIVE                      is the time since signal S was last active.

S'LAST_VALUE                      is the previous value of signal S.

S'DRIVING                               is false only if the current driver of S is a null transaction.

S'DRIVING_VALUE               is the current driving value of signal S.

E'SIMPLE_NAME                    is a string containing the name of entity E.

E'INSTANCE_NAME               is a string containing the design hierarchy including E.

E'PATH_NAME                         is a string containing the design hierarchy of E to design root.