Merge pull request #6 from Windfisch/arbitrary_number_of_ports

Allow using an arbitrary number of ports

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "usbd-midi"
 version = "0.2.0"
-authors = ["beau trepp <beautrepp@gmail.com>"]
+authors = ["beau trepp <beautrepp@gmail.com>", "Florian Jung <flo@windfis.ch>"]
 edition = "2018"
 description = "A usb-midi implementation for usb-device"
 homepage = "https://github.com/btrepp/usbd-midi"

README.md

@@ -35,7 +35,7 @@ fn main() -> ! {
 
     let usb_bus = UsbBus::new(usb);
 
-    let mut midi = MidiClass::new(&usb_bus);
+    let mut midi = MidiClass::new(&usb_bus, 1, 1);
 
     let mut usb_dev = UsbDeviceBuilder::new(&usb_bus, UsbVidPid(0x16c0, 0x5e4))
         .product("MIDI Test")
@@ -69,3 +69,19 @@ fn main() -> ! {
     }
 }
 ```
+
+## Using more than one MIDI port
+
+Calling `MidiClass::new(&usb_bus, N, M);` with `N, M >= 1` to provide more
+than one input or output port requires the `control-buffer-256` feature of
+the usb-device crate:
+
+Cargo.toml:
+```
+usb-device = { version = ">=0.2.1", features = ["control-buffer-256"] }
+```
+
+Up to 5 in/out pairs can be used this way until we again run out of buffer
+space. Note that exceeding the available buffer space will silently fail
+to send the descriptors correctly, no obvious `panic!` will hint the
+actual problem.

src/data/usb/constants.rs

@@ -7,6 +7,7 @@ pub const USB_MIDISTREAMING_SUBCLASS: u8 =0x03;
 pub const MIDI_IN_JACK_SUBTYPE : u8 = 0x02;
 pub const MIDI_OUT_JACK_SUBTYPE : u8 = 0x03;
 pub const EMBEDDED : u8 = 0x01;
+pub const EXTERNAL : u8 = 0x02;
 pub const CS_INTERFACE: u8 = 0x24;
 pub const CS_ENDPOINT: u8 = 0x25;
 pub const HEADER_SUBTYPE: u8 = 0x01;

src/midi_device.rs

@@ -16,7 +16,9 @@ pub struct MidiClass<'a,B: UsbBus> {
     standard_ac: InterfaceNumber,
     standard_mc: InterfaceNumber,
     standard_bulkout: EndpointOut<'a, B>,
-    standard_bulkin: EndpointIn<'a,B>
+    standard_bulkin: EndpointIn<'a,B>,
+    n_in_jacks: u8,
+    n_out_jacks: u8,
 }
 
 pub enum MidiReadError {
@@ -24,17 +26,30 @@ pub enum MidiReadError {
     UsbError(UsbError)
 }
 
+#[derive(Debug)]
+pub struct InvalidArguments;
+
 impl<B: UsbBus> MidiClass<'_, B> {
-    /// Creates a new MidiClass with the provided UsbBus
+    /// Creates a new MidiClass with the provided UsbBus and `n_in/out_jacks` embedded input/output jacks (or "cables",
-    pub fn new(alloc: &UsbBusAllocator<B>) -> MidiClass<'_, B> {
+    /// depending on the terminology).
-        MidiClass {
+    /// Note that a maximum of 16 in and 16 out jacks are supported.
+    pub fn new(alloc: &UsbBusAllocator<B>, n_in_jacks: u8, n_out_jacks: u8) -> core::result::Result<MidiClass<'_, B>, InvalidArguments>  {
+        if n_in_jacks > 16 || n_out_jacks > 16 {
+            return Err(InvalidArguments);
+        }
+        Ok(MidiClass {
             standard_ac: alloc.interface(),
             standard_mc: alloc.interface(),
             standard_bulkout : alloc.bulk(MAX_PACKET_SIZE as u16),
-            standard_bulkin: alloc.bulk(MAX_PACKET_SIZE as u16)
+            standard_bulkin: alloc.bulk(MAX_PACKET_SIZE as u16),
-        }
+            n_in_jacks,
+            n_out_jacks
+        })
     }
 
+    pub fn send_bytes(&mut self, buffer: [u8; 4]) -> Result<usize> {
+        self.standard_bulkin.write(&buffer)
+    }
     pub fn send_message(&mut self, usb_midi: UsbMidiEventPacket) -> Result<usize> {
         let bytes : [u8;MIDI_PACKET_SIZE] = usb_midi.into();
         self.standard_bulkin.write(&bytes)
@@ -43,14 +58,34 @@ impl<B: UsbBus> MidiClass<'_, B> {
     pub fn read(&mut self, buffer: &mut [u8]) -> Result<usize> {
         self.standard_bulkout.read(buffer)
     }
+
+    /// calculates the index'th external midi in jack id
+    fn in_jack_id_ext(&self, index: u8) -> u8 {
+        debug_assert!(index < self.n_in_jacks);
+        return 2 * index + 1;
+    }
+    /// calculates the index'th embedded midi out jack id
+    fn out_jack_id_emb(&self, index: u8) -> u8 {
+        debug_assert!(index < self.n_in_jacks);
+        return 2 * index + 2;
+    }
+
+    /// calculates the index'th external midi out jack id
+    fn out_jack_id_ext(&self, index: u8) -> u8 {
+        debug_assert!(index < self.n_out_jacks);
+        return 2 * self.n_in_jacks + 2 * index + 1;
+    }
+    /// calculates the index'th embedded midi in jack id
+    fn in_jack_id_emb(&self, index: u8) -> u8 {
+        debug_assert!(index < self.n_out_jacks);
+        return 2 * self.n_in_jacks + 2 * index + 2;
+    }
 }
 
 impl<B: UsbBus> UsbClass<B> for MidiClass<'_, B> {
 
      fn get_configuration_descriptors(&self, writer: &mut DescriptorWriter) -> Result<()> {
-        
         //AUDIO CONTROL STANDARD
-
         writer.interface(
             self.standard_ac,
             USB_AUDIO_CLASS,
@@ -79,63 +114,106 @@ impl<B: UsbBus> UsbClass<B> for MidiClass<'_, B> {
             0, //no protocol
         )?; //Num endpoints?
 
-        //Streaming extra info
+        let midi_streaming_start_byte = writer.position();
+        let midi_streaming_total_length =
+            7 + (self.n_in_jacks + self.n_out_jacks) as usize * (MIDI_IN_SIZE + MIDI_OUT_SIZE) as usize
+            + 7 + (4+self.n_out_jacks as usize) + 7 + (4+self.n_in_jacks as usize);
 
-        writer.write(
+        //Streaming extra info
+        writer.write( // len = 7
             CS_INTERFACE,
             &[
                 MS_HEADER_SUBTYPE,
                 0x00,0x01, //REVISION
-                (0x07 + MIDI_OUT_SIZE),0x00 //Total size of class specific descriptors? (little endian?)
+                (midi_streaming_total_length & 0xFF) as u8, ((midi_streaming_total_length >> 8) & 0xFF) as u8
             ]
         )?;
 
         //JACKS
+        for i in 0..self.n_in_jacks {
+            writer.write( // len = 6 = MIDI_IN_SIZE
+                CS_INTERFACE,
+                &[
+                    MIDI_IN_JACK_SUBTYPE,
+                    EXTERNAL,
+                    self.in_jack_id_ext(i), // id
+                    0x00
+                ]
+            )?;
+        }
 
-        writer.write(
+        for i in 0..self.n_out_jacks {
+            writer.write( // len = 6 = MIDI_IN_SIZE
                 CS_INTERFACE,
                 &[
                     MIDI_IN_JACK_SUBTYPE,
                     EMBEDDED,
-                0x01, // id
+                    self.in_jack_id_emb(i), // id
                     0x00
                 ]
             )?;
+        }
 
-        writer.write (
+        for i in 0..self.n_out_jacks {
+            writer.write ( // len = 9 = MIDI_OUT_SIZE
+                CS_INTERFACE,
+                &[
+                    MIDI_OUT_JACK_SUBTYPE,
+                    EXTERNAL,
+                    self.out_jack_id_ext(i), //id
+                    0x01, // 1 pin
+                    self.in_jack_id_emb(i), // pin is connected to this entity...
+                    0x01, // ...to the first pin
+                    0x00
+                ]
+            )?;
+        }
+
+        for i in 0..self.n_in_jacks {
+            writer.write ( // len = 9 = MIDI_OUT_SIZE
                 CS_INTERFACE,
                 &[
                     MIDI_OUT_JACK_SUBTYPE,
                     EMBEDDED,
-                0x01,//id
+                    self.out_jack_id_emb(i), //id
                     0x01, // 1 pin
-                0x01, // pin 1
+                    self.in_jack_id_ext(i), // pin is connected to this entity...
-                0x01, //sorta vague source pin?
+                    0x01, // ...to the first pin
                     0x00
                 ]
             )?;
+        }
 
-        writer.endpoint(&self.standard_bulkout)?;
+        let mut endpoint_data = [
-
-        writer.write(
-            CS_ENDPOINT,
-            &[
             MS_GENERAL,
-                0x01,
+            0, // number of jacks. must be filled in!
-                0x01
+            0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 // jack mappings. must be filled in and cropped.
-            ]
+        ];
+
+        writer.endpoint(&self.standard_bulkout)?; // len = 7
+
+        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.endpoint(&self.standard_bulkin)?;
+        writer.endpoint(&self.standard_bulkin)?; // len = 7
-
+        endpoint_data[1] = self.n_in_jacks;
-        writer.write(
+        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]
-                MS_GENERAL,
-                0x01,
-                0x01
-            ]
         )?;
+
+        let midi_streaming_end_byte = writer.position();
+        assert!(midi_streaming_end_byte - midi_streaming_start_byte == midi_streaming_total_length);
+
         Ok(())
     }