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Why is READ-CHAR so blindingly slow?
Date: Thu, 23 Feb 89 07:38 PST
From: rsk@SAMSON.cadr.dialnet.symbolics.com (Robert S. Kirk)
I'm writing a special file parser and discovered that READ-CHAR is
*much* slower than READ-LINE, even though it does little consing.
Theoretically, READ-CHAR create its own buffer, so it sould be only
slightly slower than READ-LINE due to extra function invocations.
MANY extra function invocations, plus a lot of extra error checking.
I thought I could be smart by creating my own buffer and filling it with
READ-CHAR. Oh, well!
It seems a waste to be creating a buffer of your own when the underlying stream
is most likely buffered anyway. Have you tried processing the data in the
system's buffers by using :READ-INPUT-BUFFER and :ADVANCE-INPUT-BUFFER. I
think you'll find that is the most efficient way to process file data.