Impl rand_core::RngCore & support all integers in Rng

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
           - stm32h7b0
           - stm32h735
     env:                        # Peripheral Feature flags
-      FLAGS: rt,xspi,sdmmc,fmc,usb_hs,rtc,ethernet,ltdc,crc
+      FLAGS: rt,xspi,sdmmc,sdmmc-fatfs,fmc,usb_hs,rtc,ethernet,ltdc,crc,rand
 
     steps:
       - uses: actions/checkout@v2

.github/workflows/nightly.yml

@@ -19,7 +19,7 @@ jobs:
           - log-semihost
           - log-rtt
     env:                        # Peripheral Feature flags
-      FLAGS: rt,xspi,sdmmc,fmc,usb_hs,rtc,ethernet,ltdc,crc
+      FLAGS: rt,xspi,sdmmc,sdmmc-fatfs,fmc,usb_hs,rtc,ethernet,ltdc,crc,rand
 
     steps:
       - uses: actions/checkout@v2

Cargo.toml

@@ -51,6 +51,11 @@ version = "0.4"
 default-features = false
 optional = true
 
+[dependencies.rand_core]
+version = "0.6"
+default-features = false
+optional = true
+
 [dev-dependencies]
 cortex-m-rt = ">=0.6.15,<0.8"
 cortex-m-rtic = { version = "0.5.8", default-features = false, features = ["cortex-m-7"] }
@@ -93,6 +98,7 @@ sdmmc-fatfs = ["embedded-sdmmc", "sdmmc"]
 ethernet = ["smoltcp"]
 rtc = ["chrono"]
 crc = []
+rand = ["rand_core"]
 rt = ["stm32h7/rt"]
 usb_hs = ["synopsys-usb-otg", "synopsys-usb-otg/hs"]
 stm32h742 = ["stm32h7/stm32h743", "device-selected", "rm0433"]

src/lib.rs

@@ -31,7 +31,7 @@
 //! External Memory
 //!
 //! * [Flexible Memory Controller (FMC)](crate::fmc) Feature gate `fmc`
-//! * [SD Card (SDMMC)](crate::sdmmc) Feature gate `sdmmc`
+//! * [SD Card (SDMMC)](crate::sdmmc) Feature gate `sdmmc` (FAT16/32 driver is available under the `sdmmc-fatfs` feature gate)
 //!
 //! Timing functions
 //!
@@ -44,7 +44,7 @@
 //! Others
 //!
 //! * [Cyclic Redundancy Check (CRC)](crate::crc) Feature gate `crc`
-//! * [Random Number Generator](crate::rng)
+//! * [Random Number Generator](crate::rng) ([rand_core::RngCore](rand_core::RngCore) is implemented under the`rand` feature gate)
 //! * [System Window Watchdog](crate::watchdog)
 
 #![cfg_attr(not(test), no_std)]

src/rng.rs

@@ -15,8 +15,8 @@ use crate::time::Hertz;
 
 #[derive(Debug)]
 pub enum ErrorKind {
-    ClockError,
-    SeedError,
+    ClockError = 0,
+    SeedError = 1,
 }
 
 trait KerClk {
@@ -131,8 +131,112 @@ macro_rules! rng_core {
     };
 }
 
-rng_core!(u32, u16, u8);
+// Only for types larger than 32 bits
+macro_rules! rng_core_large {
+    ($($type:ty),+) => {
+        $(
+            impl RngCore<$type> for Rng {
+                fn gen(&mut self) -> Result<$type, ErrorKind> {
+                    const WORDS: usize = mem::size_of::<$type>() / mem::size_of::<u32>();
+                    let mut res: $type = 0;
+
+                    for i in 0..WORDS {
+                        res |= (self.value()? as $type) << (i * (mem::size_of::<u32>() * 8))
+                    }
+
+                    Ok(res)
+                }
+
+                fn fill(&mut self, dest: &mut [$type]) -> Result<(), ErrorKind> {
+                    let len = dest.len() * (mem::size_of::<$type>() / mem::size_of::<u32>());
+                    let ptr = dest.as_mut_ptr() as *mut u32;
+                    let slice_u32 = unsafe { core::slice::from_raw_parts_mut(ptr, len) };
+                    self.fill(slice_u32)
+                }
+            }
+        )+
+    };
+}
+
+macro_rules! rng_core_transmute {
+    ($($type:ty = $from:ty),+) => {
+        $(
+            impl RngCore<$type> for Rng {
+                fn gen(&mut self) -> Result<$type, ErrorKind> {
+                    let num = <Self as RngCore<$from>>::gen(self)?;
+                    Ok(unsafe { mem::transmute::<$from, $type>(num) })
+                }
 
-// Test host may have > 32-bit types, which we don't consider.
+                fn fill(&mut self, dest: &mut [$type]) -> Result<(), ErrorKind> {
+                    let unsigned_slice = unsafe { mem::transmute::<&mut [$type], &mut [$from]>(dest) };
+                    <Self as RngCore<$from>>::fill(self, unsigned_slice)
+                }
+            }
+        )+
+    };
+}
+
+rng_core!(u8, u16, u32);
+
+// Alignment of these types must be a multiple of mem::align_of::<32>()
+rng_core_large!(u64, u128);
+
+// A and B must have the same alignment
+// rng_core_transmute!(A = B)
+// assert!(mem::align_of::<A>() == mem::align_of::<B>())
+rng_core_transmute!(
+    i8 = u8,
+    i16 = u16,
+    i32 = u32,
+    i64 = u64,
+    i128 = u128,
+    isize = usize
+);
+
+// If usize is 32 bits, use the rng_core! impl
 #[cfg(target_pointer_width = "32")]
 rng_core!(usize);
+
+// If usize is 64 bits, use the rng_core_large! impl
+#[cfg(target_pointer_width = "64")]
+rng_core_large!(usize);
+
+// rand_core
+#[cfg(feature = "rand")]
+impl rand_core::RngCore for Rng {
+    /// Generate a random u32
+    /// Panics if RNG fails.
+    fn next_u32(&mut self) -> u32 {
+        self.gen().unwrap()
+    }
+
+    /// Generate a random u64
+    /// Panics if RNG fails.
+    fn next_u64(&mut self) -> u64 {
+        self.gen().unwrap()
+    }
+
+    /// Fill a slice with random data.
+    /// Panics if RNG fails.
+    fn fill_bytes(&mut self, dest: &mut [u8]) {
+        self.fill(dest).unwrap()
+    }
+
+    /// Try to fill a slice with random data. Return an error if RNG fails.
+    fn try_fill_bytes(
+        &mut self,
+        dest: &mut [u8],
+    ) -> Result<(), rand_core::Error> {
+        self.fill(dest).map_err(|e| {
+            core::num::NonZeroU32::new(
+                rand_core::Error::CUSTOM_START + e as u32,
+            )
+            // This should never fail as long as no enum variant is equal to 0
+            .expect("Internal hal error")
+            .into()
+        })
+    }
+}
+
+#[cfg(feature = "rand")]
+impl rand_core::CryptoRng for Rng {}