PAC Designer: Why do the post-fit equations differ from my design equations using PAC-Designer?
Sometimes the relationship between input equations and post-synthesis/fit equations developed by PAC-Designer are not intuitively obvious. The synthesis and fitter systems are designed to optimally utilize the CPLD hardware. Some of the types of operations performed include creating shared intermediate nodes, combining common expressions, and reorganizing the forms (e.g. converting sum-of-products form to product-of-sum form). The post-synthesis/fit equations should be functionally equivalent to the design equations users entered.