getline.c

rtl exmple program for keil

/*----------------------------------------------------------------------------
 *      R T L   K e r n e l   E x a m p l e
 *----------------------------------------------------------------------------
 *      Name:    GETLINE.C
 *      Purpose: Line Edited Character Input
 *      Rev.:    V3.40
 *----------------------------------------------------------------------------
 *      This code is part of the RealView Run-Time Library.
 *      Copyright (c) 2004-2008 KEIL - An ARM Company. All rights reserved.
 *---------------------------------------------------------------------------*/

#include <stdio.h>

#define CNTLQ      0x11
#define CNTLS      0x13
#define DEL        0x7F
#define BACKSPACE  0x08
#define CR         0x0D
#define LF         0x0A

extern int getkey (void);             /* external function:  input character */

/*----------------------------------------------------------------------------
 *      Line Editor
 *---------------------------------------------------------------------------*/
void getline (char *line, int n) {
  int  cnt = 0;
  char c;

  do {
    if ((c = getkey ()) == CR)  c = LF;    /* read character                 */
    if (c == BACKSPACE  ||  c == DEL) {    /* process backspace              */
      if (cnt != 0)  {            
        cnt--;                             /* decrement count                */
        line--;                            /* and line pointer               */
        putchar (BACKSPACE);               /* echo backspace                 */
        putchar (' ');
        putchar (BACKSPACE);
      }
    }
    else if (c != CNTLQ && c != CNTLS) {   /* ignore Control S/Q             */
      putchar (*line = c);                 /* echo and store character       */
      line++;                              /* increment line pointer         */
      cnt++;                               /* and count                      */
    }
  } while (cnt < n - 1  &&  c != LF);      /* check limit and line feed      */
  *(line - 1) = 0;                         /* mark end of string             */
}

/*----------------------------------------------------------------------------
 * end of file
 *---------------------------------------------------------------------------*/