Fixed descriptors when device has no input or output jacks

Author: sourcebox

src/class.rs

@@ -150,10 +150,16 @@ impl<B: UsbBus> UsbClass<B> for UsbMidiClass<'_, B> {
         let midi_streaming_total_length = 7
             + (self.n_in_jacks + self.n_out_jacks) as usize
                 * (MIDI_IN_SIZE + MIDI_OUT_SIZE) as usize
-            + 9
-            + (4 + self.n_out_jacks as usize)
-            + 9
-            + (4 + self.n_in_jacks as usize);
+            + if self.n_out_jacks > 0 {
+                9 + (4 + self.n_out_jacks as usize)
+            } else {
+                0
+            }
+            + if self.n_in_jacks > 0 {
+                9 + 4 + self.n_in_jacks as usize
+            } else {
+                0
+            };
 
         // Streaming extra info
         writer.write(
@@ -233,37 +239,41 @@ impl<B: UsbBus> UsbClass<B> for UsbMidiClass<'_, B> {
             0, // jack mappings. must be filled in and cropped.
         ];
 
-        writer.endpoint_ex(&self.standard_bulkout, |data| {
-            data[0] = 0; // bRefresh
-            data[1] = 0; // bSynchAddress
-            Ok(2)
-        })?; // len = 9
-
-        endpoint_data[1] = self.n_out_jacks;
-        for i in 0..self.n_out_jacks {
-            endpoint_data[2 + i as usize] = self.in_jack_id_emb(i);
+        if self.n_out_jacks > 0 {
+            writer.endpoint_ex(&self.standard_bulkout, |data| {
+                data[0] = 0; // bRefresh
+                data[1] = 0; // bSynchAddress
+                Ok(2)
+            })?; // len = 9
+
+            endpoint_data[1] = self.n_out_jacks;
+            for i in 0..self.n_out_jacks {
+                endpoint_data[2 + i as usize] = self.in_jack_id_emb(i);
+            }
+            writer.write(
+                // len = 4 + self.n_out_jacks
+                CS_ENDPOINT,
+                &endpoint_data[0..2 + self.n_out_jacks as usize],
+            )?;
         }
-        writer.write(
-            // len = 4 + self.n_out_jacks
-            CS_ENDPOINT,
-            &endpoint_data[0..2 + self.n_out_jacks as usize],
-        )?;
 
-        writer.endpoint_ex(&self.standard_bulkin, |data| {
-            data[0] = 0; // bRefresh
-            data[1] = 0; // bSynchAddress
-            Ok(2)
-        })?; // len = 9
-
-        endpoint_data[1] = self.n_in_jacks;
-        for i in 0..self.n_in_jacks {
-            endpoint_data[2 + i as usize] = self.out_jack_id_emb(i);
+        if self.n_in_jacks > 0 {
+            writer.endpoint_ex(&self.standard_bulkin, |data| {
+                data[0] = 0; // bRefresh
+                data[1] = 0; // bSynchAddress
+                Ok(2)
+            })?; // len = 9
+
+            endpoint_data[1] = self.n_in_jacks;
+            for i in 0..self.n_in_jacks {
+                endpoint_data[2 + i as usize] = self.out_jack_id_emb(i);
+            }
+            writer.write(
+                // len = 4 + self.n_in_jacks
+                CS_ENDPOINT,
+                &endpoint_data[0..2 + self.n_in_jacks as usize],
+            )?;
         }
-        writer.write(
-            // len = 4 + self.n_in_jacks
-            CS_ENDPOINT,
-            &endpoint_data[0..2 + self.n_in_jacks as usize],
-        )?;
 
         let midi_streaming_end_byte = writer.position();
         assert!(midi_streaming_end_byte - midi_streaming_start_byte == midi_streaming_total_length);