[Zlib-devel] Some inflate_fast() statistics

[Mark Adler]

On Nov 1, 2006, at 1:20 PM, Steve Snyder wrote:
> (A mystery: according to the comments in the original code, 3 bytes
> is the minimum data size to copy.  Yet there appears to be copies
> of 1- and 2-byte lengths.  Hmm.....)

In fact, the deflate format only provides for matches of lengths 3  
through 258.

You are counting only some of the bytes being copied based on the  
piece of code that you cut out.  That part of inflate_fast() copies  
bytes from the output buffer (to the output buffer), which isn't  
always where they come from.  Sometimes they come from a saved  
sliding window.  So you are seeing a small number of cases where some  
number of bytes were copied from the sliding window, and only one or  
two are left to copy from the output buffer.

mark