stm32/spi: add support for all word sizes.

Co-Authored-By: anton smeenk <asmeenk@planet.nl>

embassy-stm32/src/dma/word.rs

@@ -0,0 +1,79 @@
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum WordSize {
+    OneByte,
+    TwoBytes,
+    FourBytes,
+}
+
+impl WordSize {
+    pub fn bytes(&self) -> usize {
+        match self {
+            Self::OneByte => 1,
+            Self::TwoBytes => 2,
+            Self::FourBytes => 4,
+        }
+    }
+}
+
+mod sealed {
+    pub trait Word {}
+}
+
+pub trait Word: sealed::Word + Default + Copy + 'static {
+    fn size() -> WordSize;
+    fn bits() -> usize;
+}
+
+macro_rules! impl_word {
+    (_, $T:ident, $bits:literal, $size:ident) => {
+        impl sealed::Word for $T {}
+        impl Word for $T {
+            fn bits() -> usize {
+                $bits
+            }
+            fn size() -> WordSize {
+                WordSize::$size
+            }
+        }
+    };
+    ($T:ident, $uX:ident, $bits:literal, $size:ident) => {
+        #[repr(transparent)]
+        #[derive(Copy, Clone, Default)]
+        pub struct $T(pub $uX);
+        impl_word!(_, $T, $bits, $size);
+    };
+}
+
+impl_word!(U1, u8, 1, OneByte);
+impl_word!(U2, u8, 2, OneByte);
+impl_word!(U3, u8, 3, OneByte);
+impl_word!(U4, u8, 4, OneByte);
+impl_word!(U5, u8, 5, OneByte);
+impl_word!(U6, u8, 6, OneByte);
+impl_word!(U7, u8, 7, OneByte);
+impl_word!(_, u8, 8, OneByte);
+impl_word!(U9, u16, 9, TwoBytes);
+impl_word!(U10, u16, 10, TwoBytes);
+impl_word!(U11, u16, 11, TwoBytes);
+impl_word!(U12, u16, 12, TwoBytes);
+impl_word!(U13, u16, 13, TwoBytes);
+impl_word!(U14, u16, 14, TwoBytes);
+impl_word!(U15, u16, 15, TwoBytes);
+impl_word!(_, u16, 16, TwoBytes);
+impl_word!(U17, u32, 17, FourBytes);
+impl_word!(U18, u32, 18, FourBytes);
+impl_word!(U19, u32, 19, FourBytes);
+impl_word!(U20, u32, 20, FourBytes);
+impl_word!(U21, u32, 21, FourBytes);
+impl_word!(U22, u32, 22, FourBytes);
+impl_word!(U23, u32, 23, FourBytes);
+impl_word!(U24, u32, 24, FourBytes);
+impl_word!(U25, u32, 25, FourBytes);
+impl_word!(U26, u32, 26, FourBytes);
+impl_word!(U27, u32, 27, FourBytes);
+impl_word!(U28, u32, 28, FourBytes);
+impl_word!(U29, u32, 29, FourBytes);
+impl_word!(U30, u32, 30, FourBytes);
+impl_word!(U31, u32, 31, FourBytes);
+impl_word!(_, u32, 32, FourBytes);