From 582b500cd996c96054615870fd13d6ab0ea77428 Mon Sep 17 00:00:00 2001 From: Jay Berkenbilt Date: Sat, 10 Oct 2009 15:10:05 +0000 Subject: start integrating windows port git-svn-id: svn+q:///qpdf/trunk@757 71b93d88-0707-0410-a8cf-f5a4172ac649 --- external-libs/zlib/contrib/asm586/README.586 | 43 ++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 external-libs/zlib/contrib/asm586/README.586 (limited to 'external-libs/zlib/contrib/asm586/README.586') diff --git a/external-libs/zlib/contrib/asm586/README.586 b/external-libs/zlib/contrib/asm586/README.586 new file mode 100644 index 00000000..6bb78f32 --- /dev/null +++ b/external-libs/zlib/contrib/asm586/README.586 @@ -0,0 +1,43 @@ +This is a patched version of zlib modified to use +Pentium-optimized assembly code in the deflation algorithm. The files +changed/added by this patch are: + +README.586 +match.S + +The effectiveness of these modifications is a bit marginal, as the the +program's bottleneck seems to be mostly L1-cache contention, for which +there is no real way to work around without rewriting the basic +algorithm. The speedup on average is around 5-10% (which is generally +less than the amount of variance between subsequent executions). +However, when used at level 9 compression, the cache contention can +drop enough for the assembly version to achieve 10-20% speedup (and +sometimes more, depending on the amount of overall redundancy in the +files). Even here, though, cache contention can still be the limiting +factor, depending on the nature of the program using the zlib library. +This may also mean that better improvements will be seen on a Pentium +with MMX, which suffers much less from L1-cache contention, but I have +not yet verified this. + +Note that this code has been tailored for the Pentium in particular, +and will not perform well on the Pentium Pro (due to the use of a +partial register in the inner loop). + +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 -- cgit v1.2.3-70-g09d2