tq multicycles

multicycles

　　1.　　determining multicycle relationship in 5 steps

　　　　1.1　　default setup relationship = set_multicycle_path -setup 1

　　　　1.2　　setup relationship = default_setup_relation + (MC_SETUP_VALUE -1)*clock_period;

　　　　1.3　　source-synchronous interface : MC_SETUP_VALUE maybe 0

　　　　1.4　　-start : launch<-- back, -end : latch--> forward; mutually exclusive

　　　　1.5　　hold relationship is determined from the setup relationship, even if the setup relationship was modified with a multicycle.

　　　　1.6　　the default hold relationship follows the setup relationship with multicycles, is called 0 edge

　　　　1.7　　hold relationship: -start :  launch--> forward, -end : latch<-- back, 

　　2.　　two common sense to use the multicycles

　　　　2.1　　open the window : clock enable

　　　　2.2　　shift the window : pipeline