The Axcelerator Family offers fast carry-chain cores for a compact design of Arithmetic Macros and Counters. Fast Carry cores for Axcelerator are available in the Variations drop-down menu.
Fast Carry Chain Macros in Variations Drop-Down Menu
You can generate FC cores via the SmartGen module generator or infer them via Actel's Synopsys Designware (DWACT). FC cores are always the most area-efficient way to implement these modules. They are superior in performance for up to 32-bit designs, although some modules may be inferior beyond 32-bit (incrementors, for example). Though SmartGen offers both architecture types (FC cores and non-FC cores), Actel recommends you use FC cores to guarantee area efficiency.
In the SmartGen GUI, you can distinguish the FC cores from non-FC cores by the prefix “FC” or "Fast Carry" (e.g. “FC High Speed” versus “High Speed”). The GUI also lists a description of the macro in the Details column in the Variety View.
The core parameters used in the GEN file also use “FC” for distinction. For example the “High Speed” Adder using fast carry chains is specified by:
LPMTYPE:LPM_FC_ADD_SUB
LPM_HINT:FC_FADD
whereas the corresponding non-FC version is specified by:
LPMTYPE:LPM_ADD_SUB
LPM_HINT:FADD