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