Faster bmp.cfg for zpaq

[Karhunen]

I removed some models from the comp section in bmp_j4.cfg, and attach the file here for your consideration. My goal was faster compression for "hi color" images
i.e. 24-bit bitmaps that have 64k or fewer colors. Speed is about 2x faster on my Win32 machine sacrificing about 20% greater file size. Roughly filesize ends up
between the lpaq and paq8 compressors.
Since I barely understand the ZPAQL syntax I am sure there must be some redundacies left in the cfg file. Constructive comments welcome.

[Matt Mahoney]

Thanks. Quick test with maxcomp/rafale.bmp. Compression times are on a 2.0 GHz T3200 (32 bit Windows) using zpaq -m1 ... -m5 and zpaqd.

1,418,810 m1.zpaq 0.7s
1,282,590 m2.zpaq 1.7s
766,644 m3.zpaq 3.1s
740,732 m4.zpaq 8.6s
704,757 m5.zpaq 33.4s
616,762 bmp_k0.zpaq 15.1s
522,053 bmp_j4.zpaq 30.4s

[Karhunen]

I bundled up some more experiments plus a test image that was rendered, and clearly public domain. Although I cannot explain how they work, the hierarchy of compression is
bmp_k0.........bmp_k9.cfg, highest to lowest and therefore slowest to fastest. All of these are modifications of bmp_j4.cfg and are useful to me for less memory per thread and
decompression times. Best performance seems to be on images with 8k <= x <= 256k colors in a 24 bit bmp file.

[Jan Ondrus]

Constructive comments welcome.

Try shufflling these lines - each line prepares context for individual model with help of r1 to r18 variables prepared above:

  d++
  a=r 3 b=r 4 a-=b b=r 2 a+=b hashd d++
  a=r 2 b=r 3 a-=b b=r 5 a+=b hashd d++
  a=r 2 a*= 2 b=r 12 a-=b hashd d++
  a=r 3 a*= 2 b=r 13 a-=b hashd d++
  a=r 4 a*= 2 b=r 16 a-=b hashd d++
  a=r 5 a*= 2 b=r 14 a-=b hashd d++
  a=r 9 b=r 18 a-=b b=r 5 a+=b hashd d++
  a=r 3 b=r 15 a-=b b=r 5 a+=b hashd d++
  a= 24 a*= 16 b=a a=r 8 a<<= 1 a&=b b=a a=r 6 a>>= 1 a|=b hashd d++

  b=r 11 a=r 9 a-=b b=r 2 a+=b hashd d++
  b=r 17 a=r 9 a-=b b=r 3 a+=b hashd d++
  a=r 2 hashd b=r 11 a=r 9 a-=b hashd d++
  a=r 9 hashd a=r 10 hashd d++
  a=r 3 hashd b=r 17 a=r 9 a-=b hashd d++
  b=r 2 a=r 3 a+=b a>>= 3 hashd a=r 9 a>>= 4 hashd a=r 10 a>>= 4 hashd d++
  a=r 6 hashd a=r 8 a>>= 4 hashd d++
  a=r 2 hashd a=r 9 hashd a=r 10 hashd d++
  a=r 3 hashd d++
  a=r 3 hashd a=r 9 hashd a=r 10 hashd d++
  a=r 2 hashd d++
  a=r 2 hashd a=r 9 hashd d++
  a=r 3 hashd a=r 9 hashd d++

for example:

line:

  a=r 3 a*= 2 b=r 13 a-=b hashd d++

means
Take variable r3, multiply it by 2 and subtract r13 from it (r3*2-r13). Use result as part of context for that model.

[Karhunen]

( zpaq 3.00+ config file for generic files version 11 {B} )
( Karhunen changed some models from -m 6 comp and hcomp from mid.cfg )
( comp isse chain decreased for speed. n=21 to n=13 result. )
( Approximately ln($1+2)*15 + 2^($1+2) MiB per thread required )

comp 7 6 0 0 13 (hh hm ph pm n) ( hh array -> 7 and hm -> 6 also reduced )
0 icm $1+10
1 cm $1+18 255
2 isse $1+14 1
3 isse 16 2
4 isse $1+13 3
5 isse $1+12 4
6 sse $1+13 3 32 255
7 match $1+16 $1+17
8 mix 12 0 7 8 255
9 mix 14 0 8 12 255
10 mix2 14 8 9 16 255
11 sse 14 1 64 255
12 mix2 10 10 11 32 255

hcomp
c++ *c=a b=c a=0 (save in rotating buffer M)
d= 1 hash *d=a
b-- d++ hash *d=a
b-- d++ hash *d=a
b-- d++ hash *d=a
b-- d++ hash *d=a
b-- d++ hash b-- hash *d=a
d++ a=*c a<<= 8 *d=a
halt
end