src/core/getkey.c

   1 /*
   2  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #include <console.h>
  20 #include <latch.h>
  21 #include <gpxe/process.h>
  22 #include <gpxe/keys.h>
  23
  24 /** @file
  25  *
  26  * Special key interpretation
  27  *
  28  */
  29
  30 #define GETKEY_TIMEOUT ( TICKS_PER_SEC / 4 )
  31
  32 /**
  33  * Read character from console if available within timeout period
  34  *
  35  * @v timeout           Timeout period, in ticks
  36  * @ret character       Character read from console
  37  */
  38 static int getchar_timeout ( unsigned long timeout ) {
  39         unsigned long expiry = ( currticks() + timeout );
  40
  41         while ( currticks() < expiry ) {
  42                 step();
  43                 if ( iskey() )
  44                         return getchar();
  45         }
  46
  47         return -1;
  48 }
  49
  50 /**
  51  * Get single keypress
  52  *
  53  * @ret key             Key pressed
  54  *
  55  * The returned key will be an ASCII value or a KEY_XXX special
  56  * constant.  This function differs from getchar() in that getchar()
  57  * will return "special" keys (e.g. cursor keys) as a series of
  58  * characters forming an ANSI escape sequence.
  59  */
  60 int getkey ( void ) {
  61         int character;
  62         int key;
  63
  64         character = getchar();
  65         if ( character != ESC )
  66                 return character;
  67
  68         key = 0;
  69         while ( ( character = getchar_timeout ( GETKEY_TIMEOUT ) ) >= 0 ) {
  70                 if ( character == '[' )
  71                         continue;
  72                 if ( ! key )
  73                         key = KEY_ANSI ( character );
  74                 if ( character >= 0x40 )
  75                         break;
  76         }
  77
  78         return ( key ? key : ESC );
  79 }