103 lines
3.2 KiB
C
103 lines
3.2 KiB
C
/*
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* Central console switch. Various console devices can be selected
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* via the build options CONSOLE_FIRMWARE, CONSOLE_SERIAL etc.
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* config.c picks up on these definitions and drags in the relevant
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* objects. The linker compiles the console_drivers table for us; we
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* simply delegate to each console_driver that we find in the table.
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*
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* Doing it this way allows for changing CONSOLE_XXX without
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* rebuilding anything other than config.o. This is extremely useful
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* for rom-o-matic.
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*/
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#include "stddef.h"
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#include "console.h"
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/* FIXME: we need a cleaner way to pick up cpu_nap(). It makes a
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* real-mode call, and so we don't want to use it with LinuxBIOS.
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*/
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#include "bios.h"
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extern struct console_driver console_drivers[];
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extern struct console_driver console_drivers_end[];
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/*****************************************************************************
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* putchar : write a single character to each console
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*****************************************************************************
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*/
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void putchar ( int character ) {
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struct console_driver *console;
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/* Automatic LF -> CR,LF translation */
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if ( character == '\n' )
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putchar ( '\r' );
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for ( console = console_drivers; console < console_drivers_end ;
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console++ ) {
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if ( ( ! console->disabled ) && console->putchar )
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console->putchar ( character );
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}
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}
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/*****************************************************************************
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* has_input : check to see if any input is available on any console,
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* and return a pointer to the console device if so
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*****************************************************************************
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*/
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static struct console_driver * has_input ( void ) {
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struct console_driver *console;
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for ( console = console_drivers; console < console_drivers_end ;
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console++ ) {
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if ( ( ! console->disabled ) && console->iskey ) {
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if ( console->iskey () )
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return console;
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}
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}
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return NULL;
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}
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/*****************************************************************************
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* getchar : read a single character from any console
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*
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* NOTE : this function does not echo the character, and it does block
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*****************************************************************************
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*/
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int getchar ( void ) {
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struct console_driver *console;
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int character = 256;
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while ( character == 256 ) {
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/* Doze for a while (until the next interrupt). This works
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* fine, because the keyboard is interrupt-driven, and the
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* timer interrupt (approx. every 50msec) takes care of the
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* serial port, which is read by polling. This reduces the
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* power dissipation of a modern CPU considerably, and also
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* makes Etherboot waiting for user interaction waste a lot
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* less CPU time in a VMware session.
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*/
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cpu_nap();
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console = has_input();
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if ( console && console->getchar )
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character = console->getchar ();
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}
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/* CR -> LF translation */
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if ( character == '\r' )
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character = '\n';
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return character;
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}
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/*****************************************************************************
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* iskey : check to see if any input is available on any console
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*****************************************************************************
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*/
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int iskey ( void ) {
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return has_input() ? 1 : 0;
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}
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