Add nonblocking RNG trait

Author: austinbes

src/lib.rs

@@ -687,6 +687,7 @@ extern crate nb;
 pub mod blocking;
 pub mod digital;
 pub mod prelude;
+pub mod rng;
 pub mod serial;
 pub mod spi;
 pub mod timer;

src/prelude.rs

@@ -26,6 +26,8 @@ pub use ::blocking::spi::{
 pub use ::digital::OutputPin as _embedded_hal_digital_OutputPin;
 #[cfg(feature = "unproven")]
 pub use ::digital::InputPin as _embedded_hal_digital_InputPin;
+#[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 +1,17 @@
+//! Random Number Generator Interface
+
+#[cfg(feature = "unproven")]
+use nb;
+
+/// Nonblocking stream of random bytes.
+#[cfg(feature = "unproven")]
+// reason: No implementations or users yet
+pub trait Read {
+    /// An enumeration of RNG errors
+    ///
+    /// May be `!` (`never_type`) for infallible implementations; i.e. software PRNGs
+    type Error;
+
+    /// Get a single byte from the RNG
+    fn read(&mut self) -> nb::Result<u8, Self::Error>;
+}