Allow finding files in the root directory

This allows you to find the cluster number of a file in the root
directory by name. The main program is a simple demo where you can type
in a filename and it will tell you the cluster number.

sw/kernel/main.c

@@ -1,6 +1,7 @@
 #include <stdint.h>
 #include <conio.h>
 #include <string.h>
+#include <stdlib.h>
 
 #include "devices/board_io.h"
 #include "devices/uart.h"
@@ -14,6 +15,7 @@ uint8_t buf[512];
 int main() {
 	int i;
 	uint16_t rca;
+	char* filename;
 
 	clrscr();
 	cprintf("Hello, world!\n");
@@ -34,7 +36,17 @@ int main() {
 	sd_select_card(rca);
 
 	fat_init();
-	exec("/test.o65");
+
+	filename = (char*)malloc(FAT_MAX_FILE_NAME);
+
+	for(;;) {
+		cprintf("Filename: ");
+		cscanf("%s", filename);
+		cprintf("\n");
+		fat_parse_path_to_cluster(filename);
+	}
+
+	//exec("/test.o65");
 
 	cprintf("Done!\n");