HPAVC/HPAVC CD-ROM.iso/TUT18.ZIP/TUT18.TXT

Text File | 1995-02-21 | 12KB | 344 lines

                   ╒═══════════════════════════════╕
                   │         W E L C O M E         │
                   │  To the VGA Trainer Program   │ │
                   │              By               │ │
                   │      DENTHOR of ASPHYXIA      │ │ │
                   ╘═══════════════════════════════╛ │ │
                     ────────────────────────────────┘ │
                       ────────────────────────────────┘

                           --==[ PART 18 ]==--



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■ Introduction

Welcome back! I know, I know, you all all shocked that this tut is out so
soon after the last one, but the reason for this is that I want to have Tut
20 out by the time PCGPE ][ is released. I probably won't get that far, but
I'll try! ;)

This tut is on file packing, and putting everything into one executeable
file. For tut 19, I am thinking of doing a bit more on explaining
assembler, and perhaps demonstrating with a fire effect or something.

My mailserver is back up, thanks to Nobody (that's his handle). You write
to [e-mail] with the subject line request-list. The
mailserver checks each incoming letter for this subject line, and if it
finds one of the specific strings, it mails you back a certain file. I
never get to see these messages! If you want to mail me personally, give
your message a unique subject name! Anyway, you can request all the tuts
through this mailserver.

I hope you are all subscribed to the Demuan List! If not, ftp it off
ftp.eng.ufl.edu every sunday. I am writing a "humor" column there until
someone can figure out something else I could write ;-).

Pipsy wants mail! She is at [e-mail] and wants to chat :)
Go on, mail her. The co-founder of ctrl-alt-del, she is also a good
graphics coder.


If you would like to contact me, or the team, there are many ways you
can do it : 1) Write a message to Grant Smith/Denthor/Asphyxia in private mail
                  on the ASPHYXIA BBS.
            2) Write to :  Grant Smith
                           P.O.Box 270 Kloof
                           3640
                           Natal
                           South Africa
            3) Call me (Grant Smith) at (031) 73 2129 (leave a message if you
                  call during varsity). Call [phone] if you call
                  from outside South Africa. (It's YOUR phone bill ;-))
            4) Write to [e-mail] in E-Mail.
            5) Write to [e-mail] to get to all of
               us at once.

NB : If you are a representative of a company or BBS, and want ASPHYXIA
       to do you a demo, leave mail to me; we can discuss it.
NNB : If you have done/attempted a demo, SEND IT TO ME! We are feeling
        quite lonely and want to meet/help out/exchange code with other demo
        groups. What do you have to lose? Leave a message here and we can work
        out how to transfer it. We really want to hear from you!

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■ Loading a PCX file

This is actually quite easy. The PCX file is divided into three sections,
mainly a 128 byte header, a data section, and a 768 byte pallette.

You can usually ignore the 128 byte header, but here it is :

0  Manufacturer     10 = ZSoft .PCX file
1  Version
2  Encoding
3  Bits Per Pixel
4  XMin, Ymin, XMax, YMax  (2 bytes each)
12 Horizontal Resolution (2 bytes)
14 Verticle Resolution (2 bytes)
16 Color pallette setting (48 bytes)
64 Reserved
65 Number of color planes
66 Bytes per line (2 bytes)
68 1 = Color    2 = Grayscale  (2 bytes)
70 Blank (58 bytes)

That makes 128 bytes.

The pallette file, which is 768 bytes, is situated at the very end of the
PCX file. The 769'th byte back should be the decimal 12, which indicates
that a VGA color pallette is to follow.

There is one thing that we have to do to get the pallette correct in VGA ...
the PCX pallette values for R,G,B are 0 to 255 respectively. To convert this
to our standard (VGA) pallette, we must divide the R,G,B values by 4, to get
them into a range of 0 to 63.

Actually decoding the image is very simple. Starting after the 128 byte
header, we read a byte.

If the top two bits of this byte are not set, we dump the value to the screen.

We check bits as follows :

if ((temp and $c0) = $c0) then ...(bits are set)... else ...(bits are not set)

C0 in hex = 11000000 in binary = 192 in decimal

Let's look at that more closely...

  temp  and  c0h
  temp  and  11000000b

That means, when represented in bit format, both corresponding bits have
to be set to one for the result to be one.

0 and 0 = 0     1 and 0 = 0    0 and 1 = 0    1 and 1 = 1

In the above case then, both of the top two bits of temp have to be set for
the result to equal 11000000b. If it does not equal that, the top two bits
are not both set, and we can put the pixel.

So

  if ((temp and $c0) = $c0) then BEGIN
  END else BEGIN
    putpixel (screenpos,0,temp,vga);
    inc (screenpos);
  END;

If the top two bits _are_ set, things change. The bottom six bits become
a loop counter, which the next byte is repeated.

  if ((temp and $c0) = $c0) then BEGIN
{    Read in next byte, temp2 here.}
    for loop1:=1 to (temp and $3f) do BEGIN
      putpixel (screenpos,0,temp2,vga);
      inc (screenpos);
    END;
  END else BEGIN
    putpixel (screenpos,0,temp,vga);
    inc (screenpos);
  END;

There is our PCX loader. You will note that by and'ing temp by $3f, I am
and'ing it by 00111111b ... in other words, clearing the top two bits.

The sample program has the above in assembler, but it is the same procedure...
and you can read tut 19 for more info on how to code in assembler.

In the sample I assume that the pic is 320x200, with a maximum size of 66432
bytes.


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■  File packing

The question is simple .. how do I get all my files into one executeable?
Having many small data files can start to look unprofessional.

An easy way to have one .exe and one .dat file when dealing with many
cel's etc. is easy .... you would alter your load procedure, which looks
as follows :

VAR temp : Array [1..5,1..256] of byte;
Procedure Init;
BEGIN
  loadcel ('pic1.cel',temp[1]);
  loadcel ('pic2.cel',temp[2]);
  loadcel ('pic3.cel',temp[3]);
  loadcel ('pic4.cel',temp[4]);
  loadcel ('pic5.cel',temp[5]);
END;

For one complile you would do this :

VAR temp : Array [1..5,1..256] of byte;
Procedure Init;
VAR f:File;
BEGIN
  loadcel ('pic1.cel',temp[1]);
  loadcel ('pic2.cel',temp[2]);
  loadcel ('pic3.cel',temp[3]);
  loadcel ('pic4.cel',temp[4]);
  loadcel ('pic5.cel',temp[5]);
  assign (f,'pic.dat');
  rewrite (f,1);
  blockwrite (f,temp,sizeof(temp));
  close (f);
END;

From then on, you would do :

VAR temp : Array [1..5,1..256] of byte;
Procedure Init;
VAR f:File;
BEGIN
  assign (f,'pic.dat');
  reset (f,1);
  blockread (f,temp,sizeof(temp));
  close (f);
END;

This means that instead of five data files, you now have one! You have also
stripped the 800 byte cel header too :) ... note that this will work for any
form of data, not just cel files.

The next logical step is to include this data in the .exe file, but the
question is how?  In an earlier tutorial, I converted my data file to
constants and placed it inside my main program. This is not good mainly
because of space restrictions ... you can only have so many constants, and
what if your data file is two megs big?

Attached with this tutorial is a solution. I have written a program that
combines your data files with your executeable file, no matter how big
the data is. The only thing you have to worry about is a small change in
your data loading methods. Lets find out what.


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■  Using the file packer

Normally you would load your data as follows :

Procedure Init;
BEGIN
  loadcel ('bob.bob',temp);
  loadpcx ('den.pcx',VGA);        { Load a PCX file }
  loaddat ('data.dat',lookup);    { Load raw data into lookup }
END;

Easy, hey? Now, using the file packer, you would change this to :

USES fpack;
Procedure Init;
BEGIN
  total := 3;
  infodat[1] := 'bob.bob';
  infodat[2] := 'den.pcx';
  infodat[3] := 'data.dat';
  loadcel (1,temp);
  loadpcx (2,VGA);
  loaddat (3,lookup);
END;

Not too difficult? Now, this is still using the normal data files on your
hard drive. You would then run PACK.EXE, select the program's .exe as the
base, then select "bob.bob", "den.pcx" and "data.dat", in order (1, 2, 3).
Hit "c" to contine, and it will combine the files. Your programs .exe file
will be able to run independantly of the separate data files on disk,
because the data files are imbedded with the .exe.

Let us take a closer look at the load procedures. Normally a load procedure
would look as follows :

Procedure LoadData (name:string; p:pointer);
VAR f:file;
BEGIN
  assign (f,name);
  reset (f,1);
  blockread (f,p^,filesize(f);
  close (f);
END;

In FPack.pas, we do the following :

Function LoadData (num:integer; p:pointer):Boolean;
VAR f:file;
BEGIN
  If pack then BEGIN
    assign (f,paramstr(0));
    reset (f,1);
    seek (f,infopos[num]);
    blockread (f, p^, infopos[num+1]-infopos[num]);
    close (f);
  END else BEGIN
    assign (f,infodat[num]);
    reset (f,1);
    blockread (f, p^, filesize (f));
    close (f);
  END;
END;

As you can see, we just have two special cases depending on weather or not
the .exe file has been packed yet.

NOTE : After you have packed the file, you CAN NOT pklite it. You can
       however pklite the .exe _before_ you run pack.exe ... in other
       words, you can not use pklite to try pack your data files.

PACK.EXE does have a limitation ... you can only pack 24 data files together.
If you would like it to do more, mail me ... It should be easy to increase the
number.

In the sample program, FINAL.EXE is the same as temp.pas, except it has
it's PCX embedded inside it. I ran pack2.exe, selected final.exe and
eye.pcx, hit "C", and there it was. You will notice that eye.pcx is not
included in the directory ... it is now part of the exe!

eye.pcx was draw by Gary Morton of iCANDi Design. The other pcx is an old
one draw by Fubar.


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■  In closing

Well, that's about it for this trainer... next one (as I have mentioned
twice already ;) will be on assembler, with a flame routine thrown in.

Any good html programmers out there? My web page really needs help ;-)

As soon as I figure out how, I will also be creating a mailing list, in
which people with internet addresses will be able to get all new trainers
dilivered directly into their mailbox's. I hope to announce something in
tut 20.

This tut has been a bit of a departure from normal tuts ... aside from the
PCX loading routines, the rest has been "non programming" oriented ...
don't worry, next weeks one will be back to normal.


Byeeeee....
  - Denthor

The following are official ASPHYXIA distribution sites :

╔══════════════════════════╦════════════════╦═════╗
║BBS Name                  ║Telephone No.   ║Open ║
╠══════════════════════════╬════════════════╬═════╣
║ASPHYXIA BBS #1           ║[phone] ║ALL  ║ *Moving*
║ASPHYXIA BBS #2           ║[phone] ║ALL  ║ *Moving*
║C-Spam BBS                ║410-531-5886    ║ALL  ║
║POP!                      ║[phone] ║ALL  ║
║Soul Asylum               ║[phone]  ║ALL  ║
║Wasted Image              ║407-838-4525    ║ALL  ║
║Reckless Life             ║351-01-716 67 58║ALL  ║
║Mach 5 BBS                ║[phone] ║ALL  ║
║House of Horror           ║[phone] ║ALL  ║
║Zero Level                ║[phone]  ║ALL  ║
╚══════════════════════════╩════════════════╩═════╝

Leave me mail if you want to become an official Asphyxia BBS
distribution site.