This is a patched version of zlib, modified to use

Pentium-Pro-optimized assembly code in the deflation algorithm. The

files changed/added by this patch are:

README.686

match.S

The speedup that this patch provides varies, depending on whether the

compiler used to build the original version of zlib falls afoul of the

PPro's speed traps. My own tests show a speedup of around 10-20% at

the default compression level, and 20-30% using -9, against a version

compiled using gcc 2.7.2.3. Your mileage may vary.

Note that this code has been tailored for the PPro/PII in particular,

and will not perform particuarly well on a Pentium.

If you are using an assembler other than GNU as, you will have to

translate match.S to use your assembler's syntax. (Have fun.)

Brian Raiter

breadbox@muppetlabs.com

April, 1998

Added for zlib 1.1.3:

The patches come from

http://www.muppetlabs.com/~breadbox/software/assembly.html

To compile zlib with this asm file, copy match.S to the zlib directory

then do:

CFLAGS="-O3 -DASMV" ./configure

make OBJA=match.o

Update:

I've been ignoring these assembly routines for years, believing that

gcc's generated code had caught up with it sometime around gcc 2.95

and the major rearchitecting of the Pentium 4. However, I recently

learned that, despite what I believed, this code still has some life

in it. On the Pentium 4 and AMD64 chips, it continues to run about 8%

faster than the code produced by gcc 4.1.

In acknowledgement of its continuing usefulness, I've altered the

license to match that of the rest of zlib. Share and Enjoy!

Brian Raiter

breadbox@muppetlabs.com

April, 2007