AR# 2363: 1.5i MAP: How can I estimate the total number of packed CLBs in my design?
1.5i MAP: How can I estimate the total number of packed CLBs in my design?
Keywords: CLB, FMAP, LUT, MAP
General Description: The number of PACKED CLBs required by a design gives the user an idea of how many CLBs would be required if the Mapper were to pack the logic into the CLBs for maximum density. (Note that doing this can adversely affect the routability of the design.)
The M1.3 mapping report does not report this parameter. It only reports the number of LUTs, Flip Flops, Latches, and occupied CLBs needed by the design.
If the number of LUTs (FMAPs) is greater or equal to the total number of flip flops and latches, a close enough approximation of the number of PACKED CLBs can be obtained by dividing the number of 4-Input LUTs by two:
Number of packed CLBs = (4_Input_LUTs) / 2
Alternatively, if the total number of non-IOB latches and flip flops is greater than then total number of LUTs then use the following formula:
Number of Packed CLBs = (Flip Flops + Latches) / 2