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