🚀 go-pugleaf

cwilkins@irscscm.UUCP (Charlie Wilkinson) writes:

>bbrown@infonode.ingr.com (Bailey Brown) writes:
>: I am writing a program and I want to use the CTRL_P key combination
>: in it.  I am using bioskey() to read keys.  When I press "ctrl-p"
>: my program does not see it, and when I exit my program, I get an
>: "abort retry fail ignore" message because the printer isn't turned
>: on.  At first I thought 4dos was up to something, but the docs say
>: that ctrl-p is intercepted by the bios and has something to do
>: with printscreen.  I there any way to get around this behavior?
> 
>If you aren't too squeamish, you could write an new keyboard interrupt,
>or at least enough to grab the ^P and notify your program, and then
>chain to the original keyboard interrupt(?). -or you could convert the
>^P to some more harmless character, feed it to the original kbd int and
>let your program detect the character at that point by more conventional
>means.  No, I've never done it before either, but it should be a piece of
>cake.  ;-)

>Hope this can at least be loosely construed as "help".

Well, while looking for some sample code to install a keyboard
interrupt handler, I came across the following code that lets
you detect and read any key combo, including ctrl+p, without 
starting the "printer not ready" monkey business.

To detect a keypress:

    int flags;
    union REGS reg;

    reg.x.ax = 0x4406;
    reg.x.bx = 0;
    int86(0x21,&reg,&reg);
    flags = reg.h.al;
    if (flags & 1)
        return TRUE;
    else
        return FALSE;


and to read the key:


    int c;

    union REGS reg;
    reg.h.ah = 0x10;
    int86(0x16, &reg, &reg);
    c = reg.x.ax;

    if ((c & 0xff) == 0 || (c & 0xff) == 0xe0)
        c = (c >> 8) | 0x1080;
    else
        c &= 0xff;
    c = c & 0x10ff;
    return c;

Is this code general?  Will it work on any (386 AT or better) dos box?
How does it work?  It looks like it is getting the key from dos.  I
thought dos was higher level than the bios, and therefore would
have as least as much bad ctrl+p type behavior as the bios.
Please shed some light.  All I know is this works on my machine.

------------
Bailey Brown                               "Above all else, confusion reigns."
Intergraph Corporation                                  
bbrown@casca.b11.ingr.com                              Procol Harum