src/core/console.c

   1 #include "stddef.h"
   2 #include <ipxe/console.h>
   3 #include <ipxe/process.h>
   4 #include <ipxe/nap.h>
   5
   6 /** @file */
   7
   8 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
   9
  10 /** Current console usage */
  11 int console_usage = CONSOLE_USAGE_STDOUT;
  12
  13 /** Console width */
  14 unsigned int console_width = CONSOLE_DEFAULT_WIDTH;
  15
  16 /** Console height */
  17 unsigned int console_height = CONSOLE_DEFAULT_HEIGHT;
  18
  19 /**
  20  * Write a single character to each console device
  21  *
  22  * @v character         Character to be written
  23  *
  24  * The character is written out to all enabled console devices, using
  25  * each device's console_driver::putchar() method.
  26  */
  27 void putchar ( int character ) {
  28         struct console_driver *console;
  29
  30         /* Automatic LF -> CR,LF translation */
  31         if ( character == '\n' )
  32                 putchar ( '\r' );
  33
  34         for_each_table_entry ( console, CONSOLES ) {
  35                 if ( ( ! ( console->disabled & CONSOLE_DISABLED_OUTPUT ) ) &&
  36                      ( console_usage & console->usage ) &&
  37                      console->putchar )
  38                         console->putchar ( character );
  39         }
  40 }
  41
  42 /**
  43  * Check to see if any input is available on any console
  44  *
  45  * @ret console         Console device that has input available, or NULL
  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 static struct console_driver * has_input ( void ) {
  52         struct console_driver *console;
  53
  54         for_each_table_entry ( console, CONSOLES ) {
  55                 if ( ( ! ( console->disabled & CONSOLE_DISABLED_INPUT ) ) &&
  56                      console->iskey ) {
  57                         if ( console->iskey () )
  58                                 return console;
  59                 }
  60         }
  61         return NULL;
  62 }
  63
  64 /**
  65  * Read a single character from any console
  66  *
  67  * @ret character       Character read from a console.
  68  *
  69  * A character will be read from the first enabled console device that
  70  * has input available using that console's console_driver::getchar()
  71  * method.  If no console has input available to be read, this method
  72  * will block.  To perform a non-blocking read, use something like
  73  *
  74  * @code
  75  *
  76  *   int key = iskey() ? getchar() : -1;
  77  *
  78  * @endcode
  79  *
  80  * The character read will not be echoed back to any console.
  81  */
  82 int getchar ( void ) {
  83         struct console_driver *console;
  84         int character;
  85
  86         while ( 1 ) {
  87                 console = has_input();
  88                 if ( console && console->getchar ) {
  89                         character = console->getchar ();
  90                         break;
  91                 }
  92
  93                 /* Doze for a while (until the next interrupt).  This works
  94                  * fine, because the keyboard is interrupt-driven, and the
  95                  * timer interrupt (approx. every 50msec) takes care of the
  96                  * serial port, which is read by polling.  This reduces the
  97                  * power dissipation of a modern CPU considerably, and also
  98                  * makes Etherboot waiting for user interaction waste a lot
  99                  * less CPU time in a VMware session.
 100                  */
 101                 cpu_nap();
 102
 103                 /* Keep processing background tasks while we wait for
 104                  * input.
 105                  */
 106                 step();
 107         }
 108
 109         /* CR -> LF translation */
 110         if ( character == '\r' )
 111                 character = '\n';
 112
 113         return character;
 114 }
 115
 116 /**
 117  * Check for available input on any console
 118  *
 119  * @ret is_available    Input is available on a console
 120  *
 121  * All enabled console devices are checked once for available input
 122  * using each device's console_driver::iskey() method.  If any console
 123  * device has input available, this call will return true.  If this
 124  * call returns true, you can then safely call getchar() without
 125  * blocking.
 126  */
 127 int iskey ( void ) {
 128         return has_input() ? 1 : 0;
 129 }
 130
 131 /**
 132  * Configure console
 133  *
 134  * @v config            Console configuration
 135  * @ret rc              Return status code
 136  *
 137  * The configuration is passed to all configurable consoles, including
 138  * those which are currently disabled.  Consoles may choose to enable
 139  * or disable themselves depending upon the configuration.
 140  *
 141  * If configuration fails, then all consoles will be reset.
 142  */
 143 int console_configure ( struct console_configuration *config ) {
 144         struct console_driver *console;
 145         int rc;
 146
 147         /* Reset console width and height */
 148         console_set_size ( CONSOLE_DEFAULT_WIDTH, CONSOLE_DEFAULT_HEIGHT );
 149
 150         /* Try to configure each console */
 151         for_each_table_entry ( console, CONSOLES ) {
 152                 if ( ( console->configure ) &&
 153                      ( ( rc = console->configure ( config ) ) != 0 ) )
 154                                 goto err;
 155         }
 156
 157         return 0;
 158
 159  err:
 160         /* Reset all consoles, avoiding a potential infinite loop */
 161         if ( config )
 162                 console_reset();
 163         return rc;
 164 }