cannam@128: This is a patched version of zlib, modified to use
cannam@128: Pentium-Pro-optimized assembly code in the deflation algorithm. The
cannam@128: files changed/added by this patch are:
cannam@128: 
cannam@128: README.686
cannam@128: match.S
cannam@128: 
cannam@128: The speedup that this patch provides varies, depending on whether the
cannam@128: compiler used to build the original version of zlib falls afoul of the
cannam@128: PPro's speed traps. My own tests show a speedup of around 10-20% at
cannam@128: the default compression level, and 20-30% using -9, against a version
cannam@128: compiled using gcc 2.7.2.3. Your mileage may vary.
cannam@128: 
cannam@128: Note that this code has been tailored for the PPro/PII in particular,
cannam@128: and will not perform particuarly well on a Pentium.
cannam@128: 
cannam@128: If you are using an assembler other than GNU as, you will have to
cannam@128: translate match.S to use your assembler's syntax. (Have fun.)
cannam@128: 
cannam@128: Brian Raiter
cannam@128: breadbox@muppetlabs.com
cannam@128: April, 1998
cannam@128: 
cannam@128: 
cannam@128: Added for zlib 1.1.3:
cannam@128: 
cannam@128: The patches come from
cannam@128: http://www.muppetlabs.com/~breadbox/software/assembly.html
cannam@128: 
cannam@128: To compile zlib with this asm file, copy match.S to the zlib directory
cannam@128: then do:
cannam@128: 
cannam@128: CFLAGS="-O3 -DASMV" ./configure
cannam@128: make OBJA=match.o
cannam@128: 
cannam@128: 
cannam@128: Update:
cannam@128: 
cannam@128: I've been ignoring these assembly routines for years, believing that
cannam@128: gcc's generated code had caught up with it sometime around gcc 2.95
cannam@128: and the major rearchitecting of the Pentium 4. However, I recently
cannam@128: learned that, despite what I believed, this code still has some life
cannam@128: in it. On the Pentium 4 and AMD64 chips, it continues to run about 8%
cannam@128: faster than the code produced by gcc 4.1.
cannam@128: 
cannam@128: In acknowledgement of its continuing usefulness, I've altered the
cannam@128: license to match that of the rest of zlib. Share and Enjoy!
cannam@128: 
cannam@128: Brian Raiter
cannam@128: breadbox@muppetlabs.com
cannam@128: April, 2007