src/core/console.c

   1 #include "stddef.h"
   2 #include "console.h"
   3 #include <gpxe/process.h>
   4
   5 /** @file */
   6
   7 #include "bios.h"
   8
   9 static struct console_driver console_drivers[0]
  10         __table_start ( struct console_driver, console );
  11 static struct console_driver console_drivers_end[0]
  12         __table_end ( struct console_driver, console );
  13
  14 /**
  15  * Write a single character to each console device.
  16  *
  17  * @v character         Character to be written
  18  * @ret None            -
  19  * @err None            -
  20  *
  21  * The character is written out to all enabled console devices, using
  22  * each device's console_driver::putchar() method.
  23  *
  24  */
  25 void putchar ( int character ) {
  26         struct console_driver *console;
  27
  28         /* Automatic LF -> CR,LF translation */
  29         if ( character == '\n' )
  30                 putchar ( '\r' );
  31
  32         for ( console = console_drivers; console < console_drivers_end ;
  33               console++ ) {
  34                 if ( ( ! console->disabled ) && console->putchar )
  35                         console->putchar ( character );
  36         }
  37 }
  38
  39 /**
  40  * Check to see if any input is available on any console.
  41  *
  42  * @v None              -
  43  * @ret console         Console device that has input available, if any.
  44  * @ret NULL            No console device has input available.
  45  * @err None            -
  46  *
  47  * All enabled console devices are checked once for available input
  48  * using each device's console_driver::iskey() method.  The first
  49  * console device that has available input will be returned, if any.
  50  *
  51  */
  52 static struct console_driver * has_input ( void ) {
  53         struct console_driver *console;
  54
  55         for ( console = console_drivers; console < console_drivers_end ;
  56               console++ ) {
  57                 if ( ( ! console->disabled ) && console->iskey ) {
  58                         if ( console->iskey () )
  59                                 return console;
  60                 }
  61         }
  62         return NULL;
  63 }
  64
  65 /**
  66  * Read a single character from any console.
  67  *
  68  * @v None              -
  69  * @ret character       Character read from a console.
  70  * @err None            -
  71  *
  72  * A character will be read from the first enabled console device that
  73  * has input available using that console's console_driver::getchar()
  74  * method.  If no console has input available to be read, this method
  75  * will block.  To perform a non-blocking read, use something like
  76  *
  77  * @code
  78  *
  79  *   int key = iskey() ? getchar() : -1;
  80  *
  81  * @endcode
  82  *
  83  * The character read will not be echoed back to any console.
  84  *
  85  * @bug We need a cleaner way to pick up cpu_nap().  It makes a
  86  * real-mode call, and so we don't want to use it with LinuxBIOS.
  87  *
  88  */
  89 int getchar ( void ) {
  90         struct console_driver *console;
  91         int character = 256;
  92
  93         while ( character == 256 ) {
  94                 /* Doze for a while (until the next interrupt).  This works
  95                  * fine, because the keyboard is interrupt-driven, and the
  96                  * timer interrupt (approx. every 50msec) takes care of the
  97                  * serial port, which is read by polling.  This reduces the
  98                  * power dissipation of a modern CPU considerably, and also
  99                  * makes Etherboot waiting for user interaction waste a lot
 100                  * less CPU time in a VMware session.
 101                  */
 102                 cpu_nap();
 103
 104                 /* Keep processing background tasks while we wait for
 105                  * input.
 106                  */
 107                 step();
 108
 109                 console = has_input();
 110                 if ( console && console->getchar )
 111                         character = console->getchar ();
 112         }
 113
 114         /* CR -> LF translation */
 115         if ( character == '\r' )
 116                 character = '\n';
 117
 118         return character;
 119 }
 120
 121 /** Check for available input on any console.
 122  *
 123  * @v None              -
 124  * @ret True            Input is available on a console
 125  * @ret False           Input is not available on any console
 126  * @err None            -
 127  *
 128  * All enabled console devices are checked once for available input
 129  * using each device's console_driver::iskey() method.  If any console
 130  * device has input available, this call will return True.  If this
 131  * call returns True, you can then safely call getchar() without
 132  * blocking.
 133  *
 134  */
 135 int iskey ( void ) {
 136         return has_input() ? 1 : 0;
 137 }