Chris@43: This is a patched version of zlib, modified to use
Chris@43: Pentium-Pro-optimized assembly code in the deflation algorithm. The
Chris@43: files changed/added by this patch are:
Chris@43: 
Chris@43: README.686
Chris@43: match.S
Chris@43: 
Chris@43: The speedup that this patch provides varies, depending on whether the
Chris@43: compiler used to build the original version of zlib falls afoul of the
Chris@43: PPro's speed traps. My own tests show a speedup of around 10-20% at
Chris@43: the default compression level, and 20-30% using -9, against a version
Chris@43: compiled using gcc 2.7.2.3. Your mileage may vary.
Chris@43: 
Chris@43: Note that this code has been tailored for the PPro/PII in particular,
Chris@43: and will not perform particuarly well on a Pentium.
Chris@43: 
Chris@43: If you are using an assembler other than GNU as, you will have to
Chris@43: translate match.S to use your assembler's syntax. (Have fun.)
Chris@43: 
Chris@43: Brian Raiter
Chris@43: breadbox@muppetlabs.com
Chris@43: April, 1998
Chris@43: 
Chris@43: 
Chris@43: Added for zlib 1.1.3:
Chris@43: 
Chris@43: The patches come from
Chris@43: http://www.muppetlabs.com/~breadbox/software/assembly.html
Chris@43: 
Chris@43: To compile zlib with this asm file, copy match.S to the zlib directory
Chris@43: then do:
Chris@43: 
Chris@43: CFLAGS="-O3 -DASMV" ./configure
Chris@43: make OBJA=match.o
Chris@43: 
Chris@43: 
Chris@43: Update:
Chris@43: 
Chris@43: I've been ignoring these assembly routines for years, believing that
Chris@43: gcc's generated code had caught up with it sometime around gcc 2.95
Chris@43: and the major rearchitecting of the Pentium 4. However, I recently
Chris@43: learned that, despite what I believed, this code still has some life
Chris@43: in it. On the Pentium 4 and AMD64 chips, it continues to run about 8%
Chris@43: faster than the code produced by gcc 4.1.
Chris@43: 
Chris@43: In acknowledgement of its continuing usefulness, I've altered the
Chris@43: license to match that of the rest of zlib. Share and Enjoy!
Chris@43: 
Chris@43: Brian Raiter
Chris@43: breadbox@muppetlabs.com
Chris@43: April, 2007