Add nonblocking RNG trait

Author: austinbes

Cargo.toml

@@ -20,6 +20,9 @@ version = "1.0.2"
 [dependencies.nb]
 version = "0.1.1"
 
+[dependencies.generic-array]
+version = "0.11.0"
+
 [dev-dependencies]
 stm32f30x = "0.6.0"
 futures = "0.1.17"
@@ -28,4 +31,4 @@ futures = "0.1.17"
 unproven = ["nb/unstable"]
 
 [package.metadata.docs.rs]
-features = ["unproven"]
+features = ["unproven"]

src/lib.rs

@@ -688,10 +688,13 @@
 #[macro_use]
 extern crate nb;
 extern crate void;
+extern crate generic_array;
 
 pub mod blocking;
 pub mod digital;
 pub mod prelude;
+#[cfg(feature = "unproven")]
+pub mod rng;
 pub mod serial;
 pub mod spi;
 pub mod timer;

src/prelude.rs

@@ -20,6 +20,8 @@ pub use digital::InputPin as _embedded_hal_digital_InputPin;
 pub use digital::OutputPin as _embedded_hal_digital_OutputPin;
 #[cfg(feature = "unproven")]
 pub use digital::ToggleableOutputPin as _embedded_hal_digital_ToggleableOutputPin;
+#[cfg(feature = "unproven")]
+pub use rng::Read as _embedded_hal_rng_Read;
 pub use serial::Read as _embedded_hal_serial_Read;
 pub use serial::Write as _embedded_hal_serial_Write;
 pub use spi::FullDuplex as _embedded_hal_spi_FullDuplex;

src/rng.rs

@@ -0,0 +1,20 @@
+//! Random Number Generator Interface
+
+use generic_array::{ArrayLength, GenericArray};
+use nb;
+
+/// Nonblocking stream of random bytes.
+#[cfg(feature = "unproven")]
+// reason: No implementation or users yet
+pub trait Read<N>
+where
+    N: ArrayLength<u8>
+{
+    /// An enumeration of RNG errors.
+    ///
+    /// For infallible implementations, will be `Void`
+    type Error;
+
+    /// Get a number of bytes from the RNG.
+    fn read(&mut self) -> nb::Result<GenericArray<u8, N>, Self::Error>;
+}