advanced/common/usb/lib.rs: cleanup– rm GET_DESCRIPTOR handling, suggest outline

advanced/common/usb/src/lib.rs

@@ -52,27 +52,17 @@ impl Request {
     ) -> Result<Self, ()> {
         // see table 9-4 (USB specification)
         const SET_ADDRESS: u8 = 5;
-        const GET_DESCRIPTOR: u8 = 6; // todo deleteme
 
-        // TODO löschen und durch instructions ersetzen
+        /* TODO implement another branch handling GET_DESCRIPTOR requests: */
-        if bmrequesttype == 0b10000000 && brequest == GET_DESCRIPTOR {
-            // see table 9-5
-            const DEVICE: u8 = 1;
 
-            let desc_ty = (wvalue >> 8) as u8;
+        /* 1. get descriptor type and descriptor index from wValue */
-            let desc_index = wvalue as u8;
-            let langid = windex;
-
-            if desc_ty == DEVICE && desc_index == 0 && langid == 0 {
-                Ok(Request::GetDescriptor {
-                    descriptor: Descriptor::Device,
-                    length: wlength,
-                })
-            } else {
-                Err(())
-            }
-        } else if bmrequesttype == 0b00000000 && brequest == SET_ADDRESS {
 
+        /* 2. confirm that the descriptor
+            - is of type DEVICE and
+            - has descriptor index 0 (i.e. it is the first implemented descriptor for this type) and
+            - has wIndex 0 (i.e. no language ID since it's not a string descriptor)
+        */
+        if bmrequesttype == 0b00000000 && brequest == SET_ADDRESS {
             // Set the device address for all future accesses.
             // Needed to successfully init when using Apple devices.
             if wvalue < 128 && windex == 0 && wlength == 0 {
@@ -85,7 +75,6 @@ impl Request {
         } else {
             Err(())
         }
-
     }
 }