Merged mcb30-realmode-redesign back to HEAD

src/core/console.c

@@ -0,0 +1,102 @@
+/*
+ * Central console switch.  Various console devices can be selected
+ * via the build options CONSOLE_FIRMWARE, CONSOLE_SERIAL etc.
+ * config.c picks up on these definitions and drags in the relevant
+ * objects.  The linker compiles the console_drivers table for us; we
+ * simply delegate to each console_driver that we find in the table.
+ *
+ * Doing it this way allows for changing CONSOLE_XXX without
+ * rebuilding anything other than config.o.  This is extremely useful
+ * for rom-o-matic.
+ */
+
+#include "stddef.h"
+#include "console.h"
+
+/* FIXME: we need a cleaner way to pick up cpu_nap().  It makes a
+ * real-mode call, and so we don't want to use it with LinuxBIOS.
+ */
+#include "bios.h"
+
+extern struct console_driver console_drivers[];
+extern struct console_driver console_drivers_end[];
+
+/*****************************************************************************
+ * putchar : write a single character to each console
+ *****************************************************************************
+ */
+
+void putchar ( int character ) {
+	struct console_driver *console;
+
+	/* Automatic LF -> CR,LF translation */
+	if ( character == '\n' )
+		putchar ( '\r' );
+
+	for ( console = console_drivers; console < console_drivers_end ;
+	      console++ ) {
+		if ( ( ! console->disabled ) && console->putchar )
+			console->putchar ( character );
+	}
+}
+
+/*****************************************************************************
+ * has_input : check to see if any input is available on any console,
+ * and return a pointer to the console device if so
+ *****************************************************************************
+ */
+static struct console_driver * has_input ( void ) {
+	struct console_driver *console;
+
+	for ( console = console_drivers; console < console_drivers_end ;
+	      console++ ) {
+		if ( ( ! console->disabled ) && console->iskey ) {
+			if ( console->iskey () )
+				return console;
+		}
+	}
+	return NULL;
+}
+
+/*****************************************************************************
+ * getchar : read a single character from any console
+ *
+ * NOTE : this function does not echo the character, and it does block
+ *****************************************************************************
+ */
+
+int getchar ( void ) {
+	struct console_driver *console;
+	int character = 256;
+
+	while ( character == 256 ) {
+		/* Doze for a while (until the next interrupt).  This works
+		 * fine, because the keyboard is interrupt-driven, and the
+		 * timer interrupt (approx. every 50msec) takes care of the
+		 * serial port, which is read by polling.  This reduces the
+		 * power dissipation of a modern CPU considerably, and also
+		 * makes Etherboot waiting for user interaction waste a lot
+		 * less CPU time in a VMware session.
+		 */
+		cpu_nap();
+		
+		console = has_input();
+		if ( console && console->getchar )
+			character = console->getchar ();
+	}
+
+	/* CR -> LF translation */
+	if ( character == '\r' )
+		character = '\n';
+
+	return character;
+}
+
+/*****************************************************************************
+ * iskey : check to see if any input is available on any console
+ *****************************************************************************
+ */
+
+int iskey ( void ) {
+	return has_input() ? 1 : 0;
+}