Merge pull request #121 from eZioPan/StringIndex-and-IAD

let `.iad()` accept a `Option<StringIndex>`

Author: ryan-summers

CHANGELOG.md

@@ -13,6 +13,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 * Added support for alternate settings on interfaces ([#114](https://github.com/rust-embedded-community/usb-device/pull/114)).
 * Added support for architectures without atomics ([#115](https://github.com/rust-embedded-community/usb-device/pull/115)).
 
+### Breaking
+* `DescriptorWriter::iad()` now requires a `Option<StringIndex>` to optionally specify a string for describing the function ([#121](https://github.com/rust-embedded-community/usb-device/pull/121))
+
 ### Changed
 * `EndpointType` enum now has fields for isochronous synchronization and usage ([#60](https://github.com/rust-embedded-community/usb-device/pull/60)).
 

src/descriptor.rs

@@ -178,18 +178,22 @@ impl DescriptorWriter<'_> {
     ///   that do not conform to any class.
     /// * `function_sub_class` - Sub-class code. Depends on class.
     /// * `function_protocol` - Protocol code. Depends on class and sub-class.
+    /// * `function_string` - Index of string descriptor describing this function
     pub fn iad(
         &mut self,
         first_interface: InterfaceNumber,
         interface_count: u8,
         function_class: u8,
         function_sub_class: u8,
         function_protocol: u8,
+        function_string: Option<StringIndex>,
     ) -> Result<()> {
         if !self.write_iads {
             return Ok(());
         }
 
+        let str_index = function_string.map_or(0, Into::into);
+
         self.write(
             descriptor_type::IAD,
             &[
@@ -198,7 +202,7 @@ impl DescriptorWriter<'_> {
                 function_class,
                 function_sub_class,
                 function_protocol,
-                0,
+                str_index,
             ],
         )?;