function to detect keyboard hit

[kenneth kahn]

Here's a variation of the code already given; I've tried it with success on
AIX, Solaris, HP-UX, Linux and WinXP:

/* get_char.c */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <termios.h>

int getch(void);   // wait for next keystroke (no echo)
int getchp(void);  // check for pending keystrokes (no echo)

int main () {
   int key;
   /*----------------------------------------------------------*
    ! Continue waiting for keystrokes until ESC is pressed     !
    *----------------------------------------------------------*/
   while (!(((key = getch()) == 0x1b) && (getchp() < 0))) {
     printf("key=%04x",key);
     /*--------------------------------------------------------*
      ! search for any pending keystrokes (e.g. function keys) !
      *--------------------------------------------------------*/
     while ((key = getchp()) > 0) {
       printf(" %04x",key);
     }
     printf("\n");
   }
   /*----------------------------------------------------------*
    ! ESC pressed; exit program                                !
    *----------------------------------------------------------*/
   printf("Escape Pressed\n");
   return 0;
}

/*----------------------------------------------------------*
  ! Wait for the next keypress (no echo)                     !
  *----------------------------------------------------------*/
int getch(void) {
   struct termios term_settings,term_settings_saved;
   int x;
   if (tcgetattr(STDIN_FILENO,&term_settings))
     return -1;
   term_settings_saved=term_settings;
   term_settings.c_lflag &= ~ICANON ;
   term_settings.c_lflag &= ~ECHO ;
   term_settings.c_cc[VMIN]=1 ;
   term_settings.c_cc[VTIME]=0;
   if (tcsetattr (STDIN_FILENO, TCSANOW, &term_settings) < 0)
   x=getchar();
   tcsetattr (STDIN_FILENO, TCSANOW, &term_settings_saved);
   return x;
}

/*----------------------------------------------------------*
  ! Check for pending keystrokes (no echo)                   !
  *----------------------------------------------------------*/
int getchp(void) {
   struct termios term_settings,term_settings_saved;
   char c;
   int x;
   if (tcgetattr(STDIN_FILENO,&term_settings))
     return -2;
   term_settings_saved=term_settings;
   term_settings.c_lflag &= ~ICANON ;
   term_settings.c_lflag &= ~ECHO ;
   term_settings.c_cc[VMIN]=0;
   term_settings.c_cc[VTIME]=0;
   if (tcsetattr (STDIN_FILENO, TCSANOW, &term_settings) < 0)
     return -2;
   x = getchar();
   tcsetattr (STDIN_FILENO, TCSANOW, &term_settings_saved);
   return x;
}

-----------------------------------
Kenneth Kahn
Senior Member of Consulting Staff
CVA R&D Hardware Emulation
Cadence Design Systems
Lake Katrine, NY