gpxe/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 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <ctype.h>
  22 #include <console.h>
  23 #include <gpxe/process.h>
  24 #include <gpxe/keys.h>
  25 #include <gpxe/timer.h>
  26
  27 /** @file
  28  *
  29  * Special key interpretation
  30  *
  31  */
  32
  33 #define GETKEY_TIMEOUT ( TICKS_PER_SEC / 4 )
  34
  35 /**
  36  * Read character from console if available within timeout period
  37  *
  38  * @v timeout           Timeout period, in ticks
  39  * @ret character       Character read from console
  40  */
  41 static int getchar_timeout ( unsigned long timeout ) {
  42         unsigned long expiry = ( currticks() + timeout );
  43
  44         while ( currticks() < expiry ) {
  45                 step();
  46                 if ( iskey() )
  47                         return getchar();
  48         }
  49
  50         return -1;
  51 }
  52
  53 /**
  54  * Get single keypress
  55  *
  56  * @ret key             Key pressed
  57  *
  58  * The returned key will be an ASCII value or a KEY_XXX special
  59  * constant.  This function differs from getchar() in that getchar()
  60  * will return "special" keys (e.g. cursor keys) as a series of
  61  * characters forming an ANSI escape sequence.
  62  */
  63 int getkey ( void ) {
  64         int character;
  65         unsigned int n = 0;
  66
  67         character = getchar();
  68         if ( character != ESC )
  69                 return character;
  70
  71         while ( ( character = getchar_timeout ( GETKEY_TIMEOUT ) ) >= 0 ) {
  72                 if ( character == '[' )
  73                         continue;
  74                 if ( isdigit ( character ) ) {
  75                         n = ( ( n * 10 ) + ( character - '0' ) );
  76                         continue;
  77                 }
  78                 if ( character >= 0x40 )
  79                         return KEY_ANSI ( n, character );
  80         }
  81
  82         return ESC;
  83 }