Returns the old length of an async-io-state.
The function async-io-state-old-length
is used to get the old length of async-io-state. old-length is an integer specifying the length of the old part in the buffer, that is the part that was seen in the previous invocation of the callback in async-io-state-read-with-checking.
LispWorks User Guide and Reference Manual - 20 Sep 2017