Thread: problems with the first tutorial :(

  1. #1

    problems with the first tutorial :(

    I'm getting errors with the first graphic tutorial.
    why did it had to contain ASM-language ((

    Anyway, this is what my program looks like:

    void SetMCGA(void);
    void MEMPutpixel(int, int, unsigned char);
    int vga=0xa000;

    void main()
    int x=100, y=100;

    void MEMPutpixel (int x, int y, unsigned char Col)

    void SetText()
    _AX = 0x0003;

    void SetMCGA()
    _AX = 0x0013;
    geninterrupt (0x10);

    I get errors on the MEMPutpixel thing, saying:
    Error BIN\Grap.CPP 60: Cannot convert 'int' to 'void *'
    Error BIN\Grap.CPP 60: Type mismatch in parameter '__s' in call to 'memset(void *,int,unsigned int)'

    I don't understand what's wrong. I used the exact code from the tutorial.
    Anyone could help me out here???

    Thanks in advance,

  2. #2
    Registered User
    Join Date
    May 2002
    instead of

    int vga=0xa000;


    int * vga=0xa000;

  3. #3
    Thanks traveller, I'll try that...

    => Error CODE\GRAPHASM.CPP 20: Cannot convert 'unsigned int' to 'int *'


    Btw, is it ok to post this here or should I have posted this in the DOS C forum instead? I'm rather new to the board (got here today, the board that is) so don't know that good how it goes around here.

  4. #4
    Registered User
    Join Date
    May 2002
    unsigned char *vga=(unsigned char *)0xA000;
    This should work. No, its fine to post this question here. The C++ board is really for generalized questions on C++ programming whereas the other boards get more specialized into areas designated by their names. However its not like you'll be stoned or anything.
    Last edited by Traveller; 07-13-2002 at 07:29 PM.

  5. #5
    Just because ygfperson's Avatar
    Join Date
    Jan 2002
    i might be wrong about this,
    but wouldn't the address be 0xA0000 instead of 0xA000?
    in protected mode flat memory addressing it's 0xA0000.
    0xA000 is used in a real-mode segmented model as a segment:
    0xA000:0x1234 for instance.

    or i could be completely wrong. just fyi, if it doesn't work, something to try.

  6. #6
    Join Date
    Aug 2001
    Besides vga being a unsigned char*
    you really shouldn't use memset just to plot a pixel.

    Try this

    inline void MEMPutpixel (int x, int y, unsigned char color) 
          vga[x + y*320] = color; 

  7. #7
    Hm, yes thanks fellas, not anymore the errors.

    But using it like that, initializing my graphics thru ASM-language.
    I run it and this is what happens:
    I see the screen flash (going to graphic mode) with some -VERY VERY SHORT- color at the top of my screen, centered and then going back to the editor.

    So, I can't get to the part where the pixel are put on screen.
    I've tried this to notice if it actually works:
    -Initialize the graphic mode
    -Put many pixel on
    -Then a delay or sleep that would give me some seconds to see if there's actually a pixel colored or not.

    It does not wait at all. So it just skips till the end of my program???

    Anyway I can compile it now with no errors and run it without any visual errors, but when compiled and maked (so I have the exe),
    and run the exe it pops up, goes back to a standard window format and says in big white letters:
    "BGI Error: Grahpics not initialized (use 'initgraph')"

    But just because BGI has some cons, so says the first graphic tutorial on the site here, I tried with the assembly language.
    So, where might the problem be?
    Or some simple ASM-piece of code that I must use?

    For a newbie to it, I really depent on others. I hope you people can help me out here.

  8. #8
    Anyone??? Please

  9. #9

  10. #10
    Sir Mister Insane Sako Klinerr1's Avatar
    Join Date
    May 2002
    you should get a username if you plan to hang out here. it is just good if people know who you are aftr a while theyll know how you work with c++ and how to answer your questiopns, well thats what happenes to me qwhen ne wpeople come. though i am not to helpful, the only board i was ever helpul was glash 'n smash (a flash 5 board) which is now gone
    Email: || AIM: MisterSako || MSN:

    -the shroom has spoken

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