Greg Hartman | 76d05dc | 2016-11-23 15:51:27 -0800 | [diff] [blame] | 1 | #include "stddef.h" |
| 2 | #include "console.h" |
| 3 | #include <gpxe/process.h> |
| 4 | #include <gpxe/nap.h> |
| 5 | |
| 6 | /** @file */ |
| 7 | |
| 8 | FILE_LICENCE ( GPL2_OR_LATER ); |
| 9 | |
| 10 | /** |
| 11 | * Write a single character to each console device. |
| 12 | * |
| 13 | * @v character Character to be written |
| 14 | * @ret None - |
| 15 | * @err None - |
| 16 | * |
| 17 | * The character is written out to all enabled console devices, using |
| 18 | * each device's console_driver::putchar() method. |
| 19 | * |
| 20 | */ |
| 21 | void putchar ( int character ) { |
| 22 | struct console_driver *console; |
| 23 | |
| 24 | /* Automatic LF -> CR,LF translation */ |
| 25 | if ( character == '\n' ) |
| 26 | putchar ( '\r' ); |
| 27 | |
| 28 | for_each_table_entry ( console, CONSOLES ) { |
| 29 | if ( ( ! console->disabled ) && console->putchar ) |
| 30 | console->putchar ( character ); |
| 31 | } |
| 32 | } |
| 33 | |
| 34 | /** |
| 35 | * Check to see if any input is available on any console. |
| 36 | * |
| 37 | * @v None - |
| 38 | * @ret console Console device that has input available, if any. |
| 39 | * @ret NULL No console device has input available. |
| 40 | * @err None - |
| 41 | * |
| 42 | * All enabled console devices are checked once for available input |
| 43 | * using each device's console_driver::iskey() method. The first |
| 44 | * console device that has available input will be returned, if any. |
| 45 | * |
| 46 | */ |
| 47 | static struct console_driver * has_input ( void ) { |
| 48 | struct console_driver *console; |
| 49 | |
| 50 | for_each_table_entry ( console, CONSOLES ) { |
| 51 | if ( ( ! console->disabled ) && console->iskey ) { |
| 52 | if ( console->iskey () ) |
| 53 | return console; |
| 54 | } |
| 55 | } |
| 56 | return NULL; |
| 57 | } |
| 58 | |
| 59 | /** |
| 60 | * Read a single character from any console. |
| 61 | * |
| 62 | * @v None - |
| 63 | * @ret character Character read from a console. |
| 64 | * @err None - |
| 65 | * |
| 66 | * A character will be read from the first enabled console device that |
| 67 | * has input available using that console's console_driver::getchar() |
| 68 | * method. If no console has input available to be read, this method |
| 69 | * will block. To perform a non-blocking read, use something like |
| 70 | * |
| 71 | * @code |
| 72 | * |
| 73 | * int key = iskey() ? getchar() : -1; |
| 74 | * |
| 75 | * @endcode |
| 76 | * |
| 77 | * The character read will not be echoed back to any console. |
| 78 | * |
| 79 | */ |
| 80 | int getchar ( void ) { |
| 81 | struct console_driver *console; |
| 82 | int character; |
| 83 | |
| 84 | while ( 1 ) { |
| 85 | console = has_input(); |
| 86 | if ( console && console->getchar ) { |
| 87 | character = console->getchar (); |
| 88 | break; |
| 89 | } |
| 90 | |
| 91 | /* Doze for a while (until the next interrupt). This works |
| 92 | * fine, because the keyboard is interrupt-driven, and the |
| 93 | * timer interrupt (approx. every 50msec) takes care of the |
| 94 | * serial port, which is read by polling. This reduces the |
| 95 | * power dissipation of a modern CPU considerably, and also |
| 96 | * makes Etherboot waiting for user interaction waste a lot |
| 97 | * less CPU time in a VMware session. |
| 98 | */ |
| 99 | cpu_nap(); |
| 100 | |
| 101 | /* Keep processing background tasks while we wait for |
| 102 | * input. |
| 103 | */ |
| 104 | step(); |
| 105 | } |
| 106 | |
| 107 | /* CR -> LF translation */ |
| 108 | if ( character == '\r' ) |
| 109 | character = '\n'; |
| 110 | |
| 111 | return character; |
| 112 | } |
| 113 | |
| 114 | /** Check for available input on any console. |
| 115 | * |
| 116 | * @v None - |
| 117 | * @ret True Input is available on a console |
| 118 | * @ret False Input is not available on any console |
| 119 | * @err None - |
| 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 | */ |
| 128 | int iskey ( void ) { |
| 129 | return has_input() ? 1 : 0; |
| 130 | } |