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[ossec-hids.git] / src / external / zlib-1.2.8 / contrib / asm686 / README.686

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+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