Visible to Intel only — GUID: mtr1430270823011
Ixiasoft
Visible to Intel only — GUID: mtr1430270823011
Ixiasoft
2.4.2.7. Counters and Accumulators
Performance-limiting loops occur rarely in small, simple counters. Counters with unnatural rollover conditions (not a power of two), or irregular increments, are more likely to have a performance-limiting critical chain. When a performance-limiting loop occurs in a small counter (roughly 8 bits or less), write the counter as a fully decoded state machine, depending on all the inputs that control the counter. The counter still contains loops, but they are smaller, and not performance-limiting. When the counter is small (roughly 8 bits or less), the Fitter implements the counter in a single LAB. This implementation makes the counter fast because all the logic is placed close together.
You can also use loop unrolling to improve counter performance.