[prompt] Replace shell_banner() with a generic prompt() function

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/usr/prompt.c

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2011 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * Prompt for keypress
+ *
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <console.h>
+#include <ipxe/timer.h>
+#include <usr/prompt.h>
+
+/**
+ * Prompt for keypress
+ *
+ * @v text		Prompt string
+ * @v wait_ms		Time to wait, in milliseconds (0=indefinite)
+ * @v key		Key to wait for (0=any key)
+ * @ret rc		Return status code
+ *
+ * Returns success if the specified key was pressed within the
+ * specified timeout period.
+ */
+int prompt ( const char *text, unsigned int wait_ms, int key ) {
+	int key_pressed;
+
+	/* Display prompt */
+	printf ( "%s", text );
+
+	/* Wait for key */
+	key_pressed = getkey ( ( wait_ms * TICKS_PER_SEC ) / 1000 );
+
+	/* Clear the prompt line */
+	while ( *(text++) )
+		printf ( "\b \b" );
+
+	/* Check for timeout */
+	if ( key_pressed < 0 )
+		return -ETIMEDOUT;
+
+	/* Check for correct key pressed */
+	if ( key && ( key_pressed != key ) )
+		return -ECANCELED;
+
+	return 0;
+}