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From: black@beno.CSS.GOV (Mike Black)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Checking for a Keystroke (in C)
Message-ID: <49724@seismo.CSS.GOV>
Date: 22 Jun 91 13:56:18 GMT
Article-I.D.: seismo.49724
References: <1991Jun19.131033.14578@schaefer.math.wisc.edu> <2676@winnie.fit.edu>
Sender: usenet@seismo.CSS.GOV
Distribution: usa
Organization: Center for Seismic Studies, Arlington, VA
Lines: 94

In article <1991Jun19.131033.14578@schaefer.math.wisc.edu> mueller@math.wisc.edu writes:
>This question probably will require a somewhat lengthy answer.  I hope that
>someone out there will take the time.
>
>I have the SAS/C compiler for the AMIGA and I want to write a routine that
>I can call that will check for a keypress.  If a key is being pressed, I want
>the routine to report the key being pressed.  If not I want it to return -1
>or some such thing.  Can anyone tell me how to do this (or direct me to some
>source code that does this)?  I have a feeling that I'm going to have to use
>the keyboard device or the input device or the console device.  If so, I'm
>really going to need some help getting started.
>

Here's what I use for Aztec C...I believe it should work on SAS also:

P.S.  This is a little demo that allows the numeric keypad to act like
cursor control until 'q' is pressed at which time you will see a 
stream of periods run across the screen until you press 'q' again.
This demonstrates the use of getchar() under RAW i/o and the small
inkey() function that I added.


#include <stdio.h>
#include <stdlib.h>
#include <sgtty.h>

main()
{
    char c;
    int x,y;

    raw(1); /* turn on raw mode */
    puts("Enter 'q' to quit");
    while((c=getchar()) != 'q') {
        switch (c) {
            case '8': printf("%c%c%c",27,'[','A'); /* cursor up */
                      break;
            case '2': printf("%c%c%c",27,'[','B'); /* cursor down */
                      break;
            case '6': printf("%c%c%c",27,'[','C'); /* cursor right */
                      break;
            case '4': printf("%c%c%c",27,'[','D'); /* cursor left */
                      break;
            case '0': printf("%c%c%c",27,'[','H');       /* cursor home */
                      break;
            case '.': printf("Enter x y:");
                      raw(0); /* turn off so we can see the x y on screen */
                      scanf("%d%d",&x,&y);
                      raw(1);
                      printf("%c[%d;%dH",27,x,y);
                      break;
            case '-': printf("%c",12); /* clear screen */
                      break;
        }
        fflush(stdout);
    }
    /* test inkey function */
    while((c=inkey()) != 'q') {printf("%c.",c);fflush(stdout);}
    raw(0);
    putchar(12); /* just to neaten the screen a little */
    return 0;
}

raw(int flag)
{
    static struct sgttyb stty,sttysave;
    static int saved;

    if (flag && !saved) {
        ioctl(fileno(stdin),TIOCGETP,&sttysave);
        ioctl(fileno(stdin),TIOCGETP,&stty);
        stty.sg_flags |= RAW;
        ioctl(fileno(stdin),TIOCSETP,&stty);
        saved=1;
    }
    else {
        if (saved) {
            ioctl(fileno(stdin),TIOCSETP,&sttysave);
            saved = 0;
        }
    }
}

int inkey(void) /* returns 0 if no key available */
{
    if (WaitForChar(Input(),1)) return getchar();
    else return 0;
}

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