Born Dead #08 19 апреля 1999

Программирование     Графика     Самиздат

Coding - compression of images (screen to text).

                             CODING


(C) UnBEL! EVER ^ Speed ​​co. ^ XTM

This material has little to do with CODING'u as such and
more directed at those who care for each sector of the disk
space. If you are really willing to spend hours thinking about
how to win a couple of sectors, use the following
helpful advice.

So, imagine a situation where pakuemy code block
contains within normal screen length 6912 bytes. The easiest
option would be to simply pack HRUST'om or HRUM'om. Can
try skompresirovat screen LASER COMPACT'om or other
program focuses on the screens. This will give a
benefit, but often unpacker Long at 100-200 bytes eat
all your achievements. If the screen is more than one, then we 
can safely use a single extractor, which again for

part does not solve the problem.

How could still save in this case sector? The solution is
at the root of the problem; have a picture pack with the 
structure screen, but on the other hand need to have a single 
decompressor to code and a picture. Take the picture is inside 
the code block and perekodiruem her columns like this as it is 
done progressive packers.


Here's a version of the program:


              SCREEN TO FONT FONT TO SCREEN

       ---------------------- ---------------------
        SCR_BUF EQU # C000 ....... ... .....


          LD DE, SCR_BUF .. ..........

          LD L, # 00 .. .....

          LD C, # 20 .. .....

  CNV_M3 LD H, # 40 .. .....

          LD B, # C0 .. .....

  CNV_M1 LD A, (HL) LD A, (DE)

          LD (DE), A LD (HL), A

          INC DE ... ..

          INC H ... .

          LD A, H .. ...

          AND # 07 ... ...

          JR NZ, CNV_M2 .. .........

          LD A, L .. ...

          ADD A, # 20 ... .....

          LD L, A .. ...

          JR C, CNV_M2 .. ........

          LD A, H .. ...

          SUB # 08 ... ...

          LD H, A .. ...

  CNV_M2 DJNZ CNV_M1 .... ......

          INC L ... .

          DEC C ... .

          JR NZ, CNV_M3 .. .........

                                    EX DE, HL

          LD HL, # 5800 LD DE, # 5800

          LD BC, # 0300 .. ........

          LDIR ....

          RET ...

Now packs the resulting block all the same HRUST / HRUM and
enjoy the savings. True poser that should be like that
This coded screen print. There is sort of like ldir'om
can not do ... Again, will have to implement back to the first
program, or decode the screen directly in memory. In any
if this or similar decoder takes place much
less than the standard LC4.0/5.0 depacker.

It may seem that this is a perversion and should not be so tense
for the sake of a sector (and sometimes two!). But there are 
situations when this same sector is simply necessary as air. 
Lastly I note that this method was successfully tested at 
MAXSOFT'om alteration few easy pieces to a FA, and MMCM'om on 
the final version Pro Tracker'a which was now to hold exactly 
100 sektrov. Presented in this paper, the program does not in 
any way yavlyayutsya ideal and if desired, depending on the 
specific situation, they certainly can prooptimizirovat both in 
size and in the run-time.