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 delay()             Delay execution while waiting for a key press
------------------------------------------------------------------------------
 Declaration
   io.hdr

 Syntax
   func uint delay extern
   param value uint uSeconds

 Arguments
   uSeconds is the number of seconds to wait for a key press.

 Return
   The code of the pressed key, or zero if no key has been pressed.

 Description
   The delay() function waits uSeconds seconds for a key stroke. If no key
   is pressed within that time, delay() returns 0, else the keycode. The
   keycode is removed from the keyboard buffer.

 Example
   #define EXAMPLE_IO
   #include example.hdr

   func int ScreenSaver
   param const char cMessage
   // Clears the screen and then prints a moving message while waiting for
   // a key. Similar to the noburnkey() library function.
   vardef
      _HSCR nScreen
      uint  nRow, nCol
      uint  uKey
   enddef
   // if there is a key in buffer, just return without saving screen
   if iskey() != 0
      return( getkey() )
   endif
   // save the screen and initialize screen coordinates to 0
   nScreen := savescrn( 0, 0, __max_row, __max_col )
   store 0 to nRow, nCol
   // move the message around while waiting for a key
   repeat
      @ nRow, nCol ?? cMessage
      uKey := delay( 1 )          // delay a second
      @ nRow, nCol ?? space( len( cMessage ) )
   
      // increment row/column positions
      nRow++
      if nRow > __max_row
         nRow := 0
      endif
      if nCol + len( cMessage ) > __max_col
         nCol := 0
      endif
   until uKey != 0
   restorescrn( nScreen )
   return( uKey )
   endproc
   
   proc Test_delay
   vardef
      char cVar
      uint uKey
   enddef
   wait "Press a key to switch on screen saver" to cVar
   uKey := ScreenSaver( "You typed " + cVar )
   wait "You typed " + chr( uKey ) + ". Press a key to quit."
   endproc

   proc main
   Test_delay()
   endproc