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/*! [`BitSlice`] view adapters for memory regions. The [`&BitSlice`][`BitSlice`] type is a referential view over existing memory. The inherent constructor functions are awkward to call, as they require function syntax rather than method syntax, and must provide a token for the memory type argument even though this is informed by the already-existing reference being used. This module provides an extension trait, [`BitView`], which provides methods on many memory types (all [`BitRegister`] integers, and slices and arrays of them) to construct [`BitSlice`] over those values. In addition, the traits [`AsBits`] and [`AsBitsMut`] are analogues of [`AsRef`] and [`AsMut`], respectively. These traits have a blanket implementation for all `A: As{Ref,Mut}<[T: BitRegister]>`, so that any type that implements a view to a suitable memory region automatically implements a view to that region’s bits. These traits are distinct because [`BitView`] combines the im/mutable view functions into one trait, and can provide specialized implementations with a slight performance increase over the generic, but `AsBits{,Mut}` can fit in the generic type system of any library without undue effort. [`AsBits`]: crate::view::AsBits [`AsBitsMut`]: crate::view::AsBitsMut [`AsMut`]: core::convert::AsMut [`AsRef`]: core::convert::AsRef [`BitRegister`]: crate::mem::BitRegister [`BitSlice`]: crate::slice::BitSlice [`BitView`]: crate::view::BitView !*/ use funty::IsNumber; use crate::{ order::BitOrder, slice::BitSlice, store::BitStore, }; /** Creates a [`BitSlice`] view over some type that supports it. This trait is implemented on all [`BitRegister`] types, and the arrays and slices of them that are supported by the standard library. This means that until type-level integers are stabilized, only arrays in `[T: BitRegister; 0 ..= 64]` will implement the trait; wider arrays will need to reborrow as slices `[T]` in order to use the slice implementation. If you have a type that contains a [`BitRegister`] type that can be viewed with this trait, then you can implement this trait by forwarding to the interior view. [`BitSlice`]: crate::slice::BitSlice [`BitRegister`]: crate::mem::BitRegister **/ pub trait BitView { /// The region’s storage type. type Store: BitStore; /// Views a memory region as a [`BitSlice`]. /// /// # Type Parameters /// /// - `O`: The bit ordering used for the region. /// /// # Parameters /// /// - `&self`: The region to view as individual bits. /// /// # Returns /// /// A `&BitSlice` view over the region at `*self`. /// /// [`BitSlice`]: crate::slice::BitSlice fn view_bits<O>(&self) -> &BitSlice<O, Self::Store> where O: BitOrder; /// Views a memory region as a mutable [`BitSlice`]. /// /// # Type Parameters /// /// - `O`: The bit ordering used for the region. /// /// # Parameters /// /// - `&mut self`: The region to view as individual mutable bits. /// /// # Returns /// /// A `&mut BitSlice` view over the region at `*self`. /// /// [`BitSlice`]: crate::slice::BitSlice fn view_bits_mut<O>(&mut self) -> &mut BitSlice<O, Self::Store> where O: BitOrder; } #[cfg(not(tarpaulin_include))] impl<T> BitView for T where T: BitStore { type Store = T; #[inline(always)] fn view_bits<O>(&self) -> &BitSlice<O, T> where O: BitOrder { BitSlice::from_element(self) } #[inline(always)] fn view_bits_mut<O>(&mut self) -> &mut BitSlice<O, T> where O: BitOrder { BitSlice::from_element_mut(self) } } impl<T> BitView for [T] where T: BitStore { type Store = T; #[inline] fn view_bits<O>(&self) -> &BitSlice<O, T> where O: BitOrder { BitSlice::from_slice(self).expect("slice was too long to view as bits") } #[inline] fn view_bits_mut<O>(&mut self) -> &mut BitSlice<O, T> where O: BitOrder { BitSlice::from_slice_mut(self) .expect("slice was too long to view as bits") } } impl<T, const N: usize> BitView for [T; N] where T: BitStore { type Store = T; #[inline] fn view_bits<O>(&self) -> &BitSlice<O, T> where O: BitOrder { BitSlice::from_slice(&self[..]) .expect("array was too long to view as bits") } #[inline] fn view_bits_mut<O>(&mut self) -> &mut BitSlice<O, T> where O: BitOrder { BitSlice::from_slice_mut(&mut self[..]) .expect("array was too long to view as bits") } } /// Helper for size awareness on `Sized` storage regions. pub trait BitViewSized: BitView + Sized { /// Counts the number of elements `T` contained in the type. const ELTS: usize; /// Counts the number of bits contained in the type. const BITS: usize = Self::ELTS * <<Self::Store as BitStore>::Mem as IsNumber>::BITS as usize; } /// Elements are equivalent to `[T; 1]`. impl<T> BitViewSized for T where T: BitStore { const ELTS: usize = 1; } impl<T, const N: usize> BitViewSized for [T; N] where T: BitStore { const ELTS: usize = N; } /** Views a region as an immutable [`BitSlice`] only. This trait is an analogue to the [`AsRef`] trait, in that it enables any type to provide an immutable-only view of a bit slice. It does not require an `AsRef<[T: BitStore]>` implementation, and a blanket implementation for all such types is provided. This allows you to choose whether to implement only one of `AsBits<T>` or `AsRef<[T]>`, and gain a [`BitSlice`] view with either choice. # Type Parameters - `T`: The underlying storage region. # Notes You are not *forbidden* from creating multiple views with different element types to the same region, but doing so is likely to cause inconsistent and surprising behavior. Refrain from implementing this trait with more than one storage argument unless you are sure that you can uphold the memory region requirements of all of them, and are aware of the behavior conflicts that may arise. [`AsRef`]: core::convert::AsRef [`BitSlice`]: crate::slice::BitSlice **/ pub trait AsBits<T> where T: BitStore { /// Views memory as a slice of immutable bits. /// /// # Type Parameters /// /// - `O`: The bit ordering used for the region. /// /// # Parameters /// /// - `&self`: The value that is providing a [`BitSlice`] view. /// /// # Returns /// /// An immutable view into some bits. /// /// [`BitSlice`]: crate::slice::BitSlice fn as_bits<O>(&self) -> &BitSlice<O, T> where O: BitOrder; } /** Views a region as a mutable [`BitSlice`]. This trait is an analogue to the [`AsMut`] trait, in that it enables any type to provide a mutable view of a bit slice. It does not require an `AsMut<[T: BitStore]>` implementation, and a blanket implementation for all such types is provided. This allows you to choose whether to implement only one of `AsBitsMut<T>` or `AsMut<[T]>`, and gain a [`BitSlice`] view with either choice. # Type Parameters - `T`: The underlying storage region. # Notes You are not *forbidden* from creating multiple views with different element types to the same region, but doing so is likely to cause inconsistent and surprising behavior. Refrain from implementing this trait with more than one storage argument unless you are sure that you can uphold the memory region requirements of all of them, and are aware of the behavior conflicts that may arise. [`AsMut`]: core::convert::AsMut [`BitSlice`]: crate::slice::BitSlice **/ pub trait AsBitsMut<T> where T: BitStore { /// Views memory as a slice of mutable bits. /// /// # Type Parameters /// /// - `O`: The bit ordering used for the region. /// /// # Parameters /// /// - `&mut self`: The value that is providing a [`BitSlice`] view. /// /// # Returns /// /// A mutable view into some bits. /// /// [`BitSlice`]: crate::slice::BitSlice fn as_bits_mut<O>(&mut self) -> &mut BitSlice<O, T> where O: BitOrder; } #[cfg(not(tarpaulin_include))] impl<A, T> AsBits<T> for A where A: AsRef<[T]>, T: BitStore, { #[inline] fn as_bits<O>(&self) -> &BitSlice<O, T> where O: BitOrder { self.as_ref().view_bits::<O>() } } #[cfg(not(tarpaulin_include))] impl<A, T> AsBitsMut<T> for A where A: AsMut<[T]>, T: BitStore, { #[inline] fn as_bits_mut<O>(&mut self) -> &mut BitSlice<O, T> where O: BitOrder { self.as_mut().view_bits_mut::<O>() } } #[cfg(test)] mod tests { use crate::{ prelude::*, view::BitViewSized, }; #[test] fn impls() { let mut byte = 0u8; let mut bytes = [0u8; 2]; assert!(byte.view_bits::<LocalBits>().not_any()); assert!(byte.view_bits_mut::<LocalBits>().not_any()); assert!(bytes.view_bits::<LocalBits>().not_any()); assert!(bytes.view_bits_mut::<LocalBits>().not_any()); assert!(bytes[..].view_bits::<LocalBits>().not_any()); assert!(bytes[..].view_bits_mut::<LocalBits>().not_any()); let mut blank: [u8; 0] = []; assert!(blank.view_bits::<LocalBits>().is_empty()); assert!(blank.view_bits_mut::<LocalBits>().is_empty()); assert_eq!(<u8 as BitViewSized>::BITS, 8); assert_eq!(<u16 as BitViewSized>::BITS, 16); assert_eq!(<u32 as BitViewSized>::BITS, 32); #[cfg(target_pointer_width = "64")] { assert_eq!(<u64 as BitViewSized>::BITS, 64); } } }