source: buchla-68k/iolib/waitcr.c

/*
   =============================================================================
        waitcr.c -- wait for a CR from the console and allow for debugging
        Version 3 -- 1987-07-15 -- D.N. Lynx Crowe
   =============================================================================
*/

#include "ram.h"

/*
   =============================================================================
        waitcr() -- wait for a CR or a CTL-G.  CR returns control to the
        caller, CTL-G invokes xtrap15(), which if it returns, returns to
        the caller.  The xtrap15() escape is to allow a convenient debug
        point whenever we wait on the console.  The character that caused
        the return  (CR or CTL-G) is returned as the value of the function.
   =============================================================================
*/

int16_t waitcr(void)
{
        int16_t c;

        BIOS(B_PUTC, CON_DEV, '\007');          /* wake up the operator */

        /* await a CR, in which case we just exit */

        while ('\r' NE (c = (0x007F & (int16_t)BIOS(B_GETC, CON_DEV))))
                if (c EQ '\007')        /* ... or a control-G */
                        xtrap15();      /* ... in which case we trap first */

        return(c);      /* return the character that caused us to exit */
}