CPLD Schematic Design Guide
3-32
Xilinx Development System
You can also specify more than one wildcard character. For example,
*AT? specifies any net names that begin with any series of characters
followed by ``AT" and end with any one character such as BAT1,
CAT2, and THAT5. If you specify *AT??, you would match BAT11,
CAT26, and THAT50.
Pattern Matching Syntax
The syntax for creating a group using pattern matching is shown
below:
group
=
predefined_group
(
pattern
)
where
predefined_group
can only be one of the following predefined
groups--FFS or PADS. The
pattern
is any string of characters used in
conjunction with one or more wildcard characters.
For flip-flops specify the output net name. For pads, specify the name
of the external net connected to the pad.
The following example illustrates creating a group that includes the
flip-flops that source nets whose names begin with $1I3/FRED.
group1=ffs($1I3/FRED*)
The following example illustrates a group that excludes certain flip-
flops whose output net names match the specified pattern:
this_group=ffs:EXCEPT:ffs(a*)
In this example, this_group includes all flip-flops except those whose
output net names begin with the letter ``a."
Additional Pattern Matching Details
In addition to using pattern matching when you create timing
groups, you can specify a predefined group qualified by a pattern any
place you specify a predefined group. The syntax below illustrates
how pattern matching can be used within a timing specification:
TS
identifier
=FROM:
predefined_group
(
pattern
):TO:
predefined_group
(
pattern
):
delay
Instead of specifying just one pattern, you can also specify a list of
patterns separated by a colon (:) as illustrated below:
some_ffs=ffs(a*:b?:c*d)
The group
some_ffs
contains flip-flops whose output net names: