README.686
1This is a patched version of zlib, modified to use
2Pentium-Pro-optimized assembly code in the deflation algorithm. The
3files changed/added by this patch are:
4
5README.686
6match.S
7
8The speedup that this patch provides varies, depending on whether the
9compiler used to build the original version of zlib falls afoul of the
10PPro's speed traps. My own tests show a speedup of around 10-20% at
11the default compression level, and 20-30% using -9, against a version
12compiled using gcc 2.7.2.3. Your mileage may vary.
13
14Note that this code has been tailored for the PPro/PII in particular,
15and will not perform particuarly well on a Pentium.
16
17If you are using an assembler other than GNU as, you will have to
18translate match.S to use your assembler's syntax. (Have fun.)
19
20Brian Raiter
21breadbox@muppetlabs.com
22April, 1998
23
24
25Added for zlib 1.1.3:
26
27The patches come from
28http://www.muppetlabs.com/~breadbox/software/assembly.html
29
30To compile zlib with this asm file, copy match.S to the zlib directory
31then do:
32
33CFLAGS="-O3 -DASMV" ./configure
34make OBJA=match.o
35
36
37Update:
38
39I've been ignoring these assembly routines for years, believing that
40gcc's generated code had caught up with it sometime around gcc 2.95
41and the major rearchitecting of the Pentium 4. However, I recently
42learned that, despite what I believed, this code still has some life
43in it. On the Pentium 4 and AMD64 chips, it continues to run about 8%
44faster than the code produced by gcc 4.1.
45
46In acknowledgement of its continuing usefulness, I've altered the
47license to match that of the rest of zlib. Share and Enjoy!
48
49Brian Raiter
50breadbox@muppetlabs.com
51April, 2007
52