HMAP

H Function Generator Partitioning Control Symbol

The HMAP symbol is used to control logic partitioning into 3-input H function generators for XC4000 and Spartans. It is usually used with FMAP, which partitions logic into F and G function generators. You can implement a portion of logic using gates, latches, and flip-flops and specify the logic to be grouped into F, G, and H function generators by naming logic signals and HMAP/FMAP signals correspondingly. These symbols are used for mapping control in addition to the actual gates, latches, and flip-flops and not as a substitute for them. The following figure gives an example of how logic can be placed using HMAP and FMAP symbols.

Figure 6.2 Partitioning Logic Using FMAP and HMAP Symbols

The MAP=type parameter can only be set to the default value, PUC, for the HMAP symbol. PUC means pins are not locked to the signals but the CLB is closed to addition or removal of logic.

The HMAP symbol can be assigned to specific CLB locations using LOC attributes. Refer to the “LOC” section of the “Attributes, Constraints, and Carry Logic” chapter for more information on assigning LOC attributes.