/* This macro shifts a marked block of text left or right. You can do */
/* the same thing my marking the area to indent, using the 'indent' */
/* block command, and using the arrow keys. */

shift()
{
  int line1, line2;
  int n, j;

  /* Prompt the user for the indent width, and check for a bad number. */
  n = atoi(get_tty_str("How many spaces (default 2) ?"));
  if (n == 0)  n = 2;

  line1 = marked_line();    /* get the marked range */
  line2 = currlinenum();
  goline(line1);            /* set the cursor to the start of the area */
  gobol();

  while (currlinenum() <= line2)
  {
    if (n >= 0)         /* shift rightwards - insert n spaces */
    {
      gobol();
      insert(repstr(" ", n));
    }
    else                /* a negative amount means to shift leftwards */
    {
      j = -n;
      while (j > 0)     /* delete 'n' characters */
      {
        delchar();
        j = j - 1;
      }
    }
    down();             /* move down to the next line */
  }

  clear_mark();         /* remove any existing marks */
}