implement asynchronous bulk/control transfers

Cargo.toml

@@ -27,3 +27,4 @@ libc = "0.2"
 [dev-dependencies]
 regex = "1"
 usb-ids = "0.2.2"
+tokio = { version = "1", features = ["full"] }

examples/read_async.rs

@@ -0,0 +1,49 @@
+use rusb::{Context, UsbContext};
+
+use std::str::FromStr;
+use std::sync::Arc;
+use std::time::Duration;
+
+const BUF_SIZE: usize = 64;
+
+fn convert_argument(input: &str) -> u16 {
+    if input.starts_with("0x") {
+        return u16::from_str_radix(input.trim_start_matches("0x"), 16).unwrap();
+    }
+    u16::from_str_radix(input, 10)
+        .expect("Invalid input, be sure to add `0x` for hexadecimal values.")
+}
+
+#[tokio::main]
+async fn main() {
+    let args: Vec<String> = std::env::args().collect();
+
+    if args.len() < 4 {
+        eprintln!("Usage: read_async <base-10/0xbase-16> <base-10/0xbase-16> <endpoint>");
+        return;
+    }
+
+    let vid = convert_argument(args[1].as_ref());
+    let pid = convert_argument(args[2].as_ref());
+    let endpoint: u8 = FromStr::from_str(args[3].as_ref()).unwrap();
+
+    let ctx = Context::new().expect("Could not initialize libusb");
+    let device = Arc::new(
+        ctx.open_device_with_vid_pid(vid, pid)
+            .expect("Could not find device"),
+    );
+
+    let timeout = Duration::from_secs(10);
+    let mut buffer = Vec::with_capacity(BUF_SIZE);
+
+    loop {
+        let (bytes, n) = device
+            .read_bulk_async(endpoint, buffer, timeout)
+            .await
+            .expect("Failed to submit transfer");
+
+        println!("Got data: {} {:?}", n, &bytes[..n]);
+
+        buffer = bytes;
+    }
+}