Assertion System Functions and Tasks - SVA: The Power of Assertions in SystemVerilog - page 155

Table 7.8 Assertion type

Va l u e Assertion type

values

1 Concurrent

2 Simple Immediate

4 Observed Deferred Immediate

Final Deferred Immediate

8

Expect

16

Unique

32

Unique0

64

Priority

128

Table 7.9 Directive type

Va l u e Directive type

values

Assert

1

Cover

2

Assume

4

The second argument assertion_type selects the type of statements on which the
control function is applied. Table 7.8 specifies the statement type options and the
associated argument values. The available statements for selection include assertion
types such as concurrent and immediate, unique, unique0 and priority for runtime
violations of case and if statements, and expect statements. Each argument value for
the selected statement type is specified by a single designated bit in the argument
integer, such that more than one type of statement can be selected by computing the
union of the corresponding values. For example, concurrent assertion statements are
selected by value 1, final deferred immediate type is selected by 8, so value 9 selects
both of them. The argument itself is optional, which defaults to value 255 when the
argument is omitted. Value 255 includes all types.
The third argument directive_type selects the assertion directive types and
is useful only when the selection via argument assertion_type is of assertion
statement types. The directive type options are enumerated in Table 7.9 .Likethe
assertion_type argument, multiple directive types can be selected by computing the
union of the corresponding values. For example, value 3 will select assert and cover
directives. The argument is optional, which defaults to value 7, when the argument
is omitted. Value 7 selects all directive types.
The fourth argument levels specifies levels as described in Sect. 7.3.1 .This
argument is also optional and defaults to level 0 when omitted, selecting full
hierarchies of scopes specified by argument list_of_scopes_or_assertions .
The fifth argument list_of_scopes_or_assertions specifies a list of items on which
the selection of previous arguments is applied as described in Sect. 7.3.1 . Each item
is either an assertion or a scope to control. If the argument is omitted, then the
selections are applied on all top-level scopes.
Although $assertcontrol requires more arguments to specify, the task offers
comprehensive functionality. It simplifies many situations where a manual grouping
of assertions either by name or other means would be necessary for controlling