The CPLD Fitter offers three Implementation Templates, each with a preset combination of optimization settings targeting a particular fitting strategy.
Optimize Balanced template is the suggested starting point for new designs, and is the default. The optimization parameters are:
Use Local Macrocell Feedback = On (XC9500 only)
Use Pin Feedback = On (XC9500 only)
Optimize Speed template can be used to trade off density for more speed when design are not completely flattened. The optimization parameters are:
Use Local Macrocell Feedback = On (XC9500 only)
Use Pin Feedback = On (XC9500 only)
Optimize Density template is used to fit a design to a target device when flattening uses up too many resources and when performance is not critical. The optimization parameters are:
Use Timing Optimization = Off (Collapsing occurs only when
it results in a net reduction in p-terms.)
Collapsing p-term limit = 90 (no absolute limit)
Use Local Macrocell Feedback = Off
Use Pin Feedback = Off
When any of the above 3 templates are selected, the remaining optimization parameters are set as follows:
Use Multi-level Logic Optimization = On
Use Advanced Fitting = On
Enable D/T Type Transformation Optimization = On
Collapsing input limit = 36 for XC9500, 54 for XC9500XL and XC9500XV