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