Higher level: Behavioural or Logical ?

There are two primary, higher levels we can consider:

• Behavioural Expression: Using software-like code, where threads have stacks and pass between modules, and so on...
• Declarative/Logical Expression: Constraining assertions about the allowable behaviour are given.

There is a related subject of back-end synthesis: netlist generation, re-encoding and re-pipelining to meet timing closure and power budgets.