OpenCores
URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [zlib/] [contrib/] [asm586/] [README.586] - Blame information for rev 745

Details | Compare with Previous | View Log

Line No. Rev Author Line
1 745 jeremybenn
This is a patched version of zlib modified to use
2
Pentium-optimized assembly code in the deflation algorithm. The files
3
changed/added by this patch are:
4
 
5
README.586
6
match.S
7
 
8
The effectiveness of these modifications is a bit marginal, as the the
9
program's bottleneck seems to be mostly L1-cache contention, for which
10
there is no real way to work around without rewriting the basic
11
algorithm. The speedup on average is around 5-10% (which is generally
12
less than the amount of variance between subsequent executions).
13
However, when used at level 9 compression, the cache contention can
14
drop enough for the assembly version to achieve 10-20% speedup (and
15
sometimes more, depending on the amount of overall redundancy in the
16
files). Even here, though, cache contention can still be the limiting
17
factor, depending on the nature of the program using the zlib library.
18
This may also mean that better improvements will be seen on a Pentium
19
with MMX, which suffers much less from L1-cache contention, but I have
20
not yet verified this.
21
 
22
Note that this code has been tailored for the Pentium in particular,
23
and will not perform well on the Pentium Pro (due to the use of a
24
partial register in the inner loop).
25
 
26
If you are using an assembler other than GNU as, you will have to
27
translate match.S to use your assembler's syntax. (Have fun.)
28
 
29
Brian Raiter
30
breadbox@muppetlabs.com
31
April, 1998
32
 
33
 
34
Added for zlib 1.1.3:
35
 
36
The patches come from
37
http://www.muppetlabs.com/~breadbox/software/assembly.html
38
 
39
To compile zlib with this asm file, copy match.S to the zlib directory
40
then do:
41
 
42
CFLAGS="-O3 -DASMV" ./configure
43
make OBJA=match.o

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.