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18.104.22.168. Multicycle Clock Hold
By default, the Timing Analyzer performs a single-cycle path analysis. When analyzing a path, the Timing Analyzer performs two hold checks. The first hold check determines that the data that launches from the current launch edge is not captured by the previous latch edge. The second hold check determines that the data that launches from the next launch edge is not captured by the current latch edge. The Timing Analyzer reports only the most restrictive hold check. The Timing Analyzer calculates the hold check by comparing launch and latch edges.
A start multicycle hold assignment modifies the launch edge of the source clock by moving the launch edge the number of clock periods you specify to the right of the default launch edge. The following figure shows various values of the start multicycle hold (SMH) assignment and the resulting launch edge.
An end multicycle hold assignment modifies the latch edge of the destination clock by moving the latch edge the specific number of clock periods to the left of the default latch edge. The following figure shows various values of the end multicycle hold (EMH) assignment and the resulting latch edge.
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