问题
I'm not understanding my professor means when he says the write flag and read flag. Does 0 mean it is triggered? He wants us to draw a state transition diagram but I think I can do that myself if I knew what was going on.
+---------+------------+-----------+----------------+ | Counter | Write flag | Read flag | Interpretation | +---------+------------+-----------+----------------+ | 0 | 0 | 0 | Write locked | | 0 | 0 | 1 | Invalid | | 0 | 1 | 0 | Invalid | | 0 | 1 | 1 | Available | | N | 0 | 0 | Write request | | N | 0 | 1 | Read locked | | N | 1 | 0 | Invalid | | N | 1 | 1 | Invalid | +---------+------------+-----------+----------------+
回答1:
The write flag and the read flag are each a boolean value, meaning it can hold a 0 or a 1. The state appears to be defined by the value of the counter and the two flags. I think your professor is asking that you draw a state diagram that shows transitions between different counter/flag value combinations. (My guess is that the intent is that you collapse all the counter>0 sub-states into a single sub-state labeled counter=N.)
来源：https://stackoverflow.com/questions/6524262/state-transition-diagram-for-reader-writer-problem