The Android Open Source Project | 9e38dfa | 2009-03-03 19:31:38 -0800 | [diff] [blame] | 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 |
Elliott Hughes | 381716e | 2010-04-19 17:17:14 -0700 | [diff] [blame] | 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 |