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