o add gnususb as reference bootloader

o refactor boot loader  cpde
o

tools/gnusb/bootloader/usb_cmds.h

@@ -0,0 +1,38 @@
+/*
+ * =====================================================================================
+ *
+ *       Filename:  usb_cmds.h
+ *
+ *    Description:
+ *
+ *        Version:  1.0
+ *        Created:  05/06/2009 03:06:26 PM
+ *       Revision:  none
+ *       Compiler:  gcc
+ *
+ *         Author:  David Voswinkel (DV), david@optixx.org
+ *        Company:  Optixx
+ *
+ * =====================================================================================
+ */
+// start firmware upload (sets page adress to 0)
+#define SNESRAM_BOOT_CMD_START 	0xf1
+
+// write one word to flash buffer, write page if filled up
+#define SNESRAM_BOOT_CMD_WRITE 	0xf2
+
+// write last page if there's anything left to write tpo flash
+#define SNESRAM_BOOT_CMD_FINISH 	0xf3
+
+// leave bootloader and start main application
+#define SNESRAM_BOOT_CMD_LEAVE 	0xf4
+
+// clear software jumper in EEPROM to prevent bootloader from starting 
+#define SNESRAM_BOOT_CMD_CLEAR_FLAG 	0xf5
+
+// get bootloader version
+#define SNESRAM_BOOT_CMD_GET_VERSION 	0xf6
+
+#define SNESRAM_BOOT_CMD_STATUS 	0xf7
+
+#define SNESRAM_BOOT_CMD_ENTER 	0xf8