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//! Best-effort safe wrapper for progmem.
//!
//! This module offers the [`ProgMem`] struct that wraps pointers into progmem,
//! and only gives access to that value via methods that first load the value
//! into the normal data memory domain.
//! This is also the reason why the value must be `Copy` and is always returned
//! by-value instead of by-reference (since the value is not in the data memory
//! where it could be referenced).
//!
//! Since the `ProgMem` struct loads the value using special instructions,
//! it really must be in progmem, otherwise it would be **undefined behavior**
//! to use any of its methods.
//! Therefore, its constructor is `unsafe` where the
//! caller must guarantee that the given pointer truly points to a valid value
//! stored in progmem.
//!
//! As convenience, the [`progmem`] macro is offered that will create
//! a `static` in progmem with the given value and wrap a pointer to it in the
//! [`ProgMem`] struct for you.
use derivative::Derivative;
#[cfg(doc)]
use crate::progmem;
use crate::raw::read_value;
/// Best-effort safe wrapper around a value in program memory.
///
/// This type wraps a pointer to a value that is stored in program memory,
/// and offers safe functions to [`load`](ProgMem::load) that value from
/// program memory into the data memory domain from where it can be normally
/// used.
///
/// Since its constructor is the single most critical point in its API,
/// it is `unsafe`, despite it is supposed to be a safe wrapper (hence the
/// 'best-effort' notation).
/// The caller of the constructor therefore must ensure that the supplied
/// pointer points to a valid value stored in program memory.
///
/// Consequently, the only way to use this struct soundly is to define a
/// `static` with the `#[link_section = ".progmem.data"]` attribute on it and
/// pass a pointer to that `static` to `ProgMem::new`.
/// However, having an accessible `static` around that is stored in progmem
/// is a very dangerous endeavor.
///
/// In order to make working with progmem safer and more convenient,
/// consider using the [`progmem`] macro, that will put the given data
/// into a hidden `static` in progmem and provide you with an accessible static
/// containing the pointer to it wrapped in `ProgMem`.
///
/// Since this is just a fancy immutable pointer type, it can always be
/// copied/cloned (just copies the address). It also implements `Debug`,
/// which simply prints the address (into progmem) of the wrapped value.
/// And you can even coerce the pointed-to type e.g. from an statically sized
/// array to a dynamically sized slice type (it also allow to coerce to a trait
/// object, but those will not be useful at all), either using the
/// [`as_slice`][ProgMem::as_slice] method, or by enabling the "unsize" crate
/// feature that allows normal Rust coercing.
///
///
/// # Safety
///
/// The `target` pointer in this struct must point to a valid object of type
/// `T` that is stored in the program memory domain.
/// The object must be initialized, readable, and immutable (i.e. it must not
/// be changed).
/// Also the `target` pointer must be valid for the `'static` lifetime.
///
/// However, the requirement about the program memory domain only applies
/// to the AVR architecture (`#[cfg(target_arch = "avr")]`),
/// otherwise normal data access primitives are used.
/// This means that the value must be stored in the
/// regular data memory domain for ALL OTHER architectures! This still
/// holds, even if such other architecture is of the Harvard architecture,
/// because this is an AVR-only crate, not a general Harvard architecture
/// crate!
///
//
//
// SAFETY: Must not be publicly creatable
#[non_exhaustive]
//
// We use Derivative here to get rid of the constraint on the impls, which
// a normal derive would add.
#[derive(Derivative)]
// This is just a pointer type/wrapper thus it is safe & sound to just copy it.
// Notice, it will just copy the pointer (i.e. the address), thus `T` doesn't
// even need to implement any of these traits.
#[derivative(Copy(bound = ""), Clone(bound = ""), Debug(bound = ""))]
pub struct ProgMem<T: ?Sized> {
/// Points to some `T` in progmem.
///
/// # Safety
///
/// See the struct doc.
target: *const T,
}
/// Implement `uDebug` by hand, because the derive variant adds a sized constraint.
///
#[cfg(feature = "ufmt")]
impl<T: ?Sized> ufmt::uDebug for ProgMem<T> {
fn fmt<W>(&self, fmt: &mut ufmt::Formatter<'_, W>) -> Result<(), W::Error>
where
W: ufmt::uWrite + ?Sized,
{
fmt.debug_struct("ProgMem")?
// It be better to just pass the pointer as is,
// however `ufmt` has - for what ever reason - a size constraint,
// so we first cast it down to a sized type.
.field("target", &self.target.cast::<()>())?
.finish()
}
}
unsafe impl<T: ?Sized> Send for ProgMem<T> {
// SAFETY: pointers per-se are sound to send & share.
// Further more, we will never mutate the underling value, thus `ProgMem`
// can be considered as some sort of sharable `'static` "reference".
// Thus it can be shared and transferred between threads.
}
unsafe impl<T: ?Sized> Sync for ProgMem<T> {
// SAFETY: pointers per-se are sound to send & share.
// Further more, we will never mutate the underling value, thus `ProgMem`
// can be considered as some sort of sharable `'static` "reference".
// Thus it can be shared and transferred between threads.
}
impl<T: ?Sized> ProgMem<T> {
/// Return the raw pointer to the inner value.
///
/// Notice that the returned pointer is indeed a pointer into the progmem
/// domain! It may **never** be dereferenced via the default Rust operations.
/// That means a `unsafe{*pm.as_ptr()}` is **undefined behavior**!
///
/// Instead, if you want to use the pointer, you may want to use one of
/// the "raw" functions, see the [raw](crate::raw) module.
///
pub fn as_ptr(&self) -> *const T {
self.target
}
}
impl<T> ProgMem<T> {
/// Construct a new instance of this type.
///
/// This struct is a pointer wrapper for data in the program memory domain.
/// Therefore when constructing this struct, it must be guaranteed
/// that the pointed data is stored in progmem!
/// This contract is expressed by the fact that this function is `unsafe`.
/// See the Safety section for details.
///
/// You should not need to call this function directly.
/// It is recommended to use the [`progmem`] macro instead (which calls
/// this constructor for you, while enforcing its contract.
///
///
/// # Safety
///
/// The `ProgMem` wrapper is build around the invariant that the wrapped
/// pointer is stored in the program code memory domain (on the AVR
/// architecture).
///
/// That means that this function is only sound to call, if the value to
/// which `target` points is stored in a `static` that is stored in progmem,
/// e.g. by using the attribute `#[link_section = ".progmem.data"]`.
///
/// However, the above requirement about the program memory domain only
/// applies to the AVR architecture (`#[cfg(target_arch = "avr")]`),
/// otherwise normal data access primitives are used,
/// and thus the `target` pointer needs to point to normal data on those
/// architectures.
///
pub const unsafe fn new(target: *const T) -> Self {
ProgMem {
target,
}
}
}
impl<T: Copy> ProgMem<T> {
/// Read the inner value from progmem and return a regular value.
///
/// # Panics
///
/// This method panics, if the size of the value (i.e. `size_of::<T>()`)
/// is beyond 255 bytes.
/// However, this is currently just a implementation limitation, which may
/// be lifted in the future.
///
/// Also notice, if you really hit this limit, you would need 256+ bytes on
/// your stack, on the Arduino Uno (at least) that means that you might be
/// close to a stack overflow. Thus it might be better to restructure your
/// data, so you can store it as an array of something, than you can use
/// the [`load_at`] and [`load_sub_array`] methods instead.
///
/// [`load_at`]: struct.ProgMem.html#method.load_at
/// [`load_sub_array`]: struct.ProgMem.html#method.load_sub_array
///
pub fn load(&self) -> T {
// This is safe, because the invariant of this struct guarantees that
// this value (i.e. target) is stored in the progmem domain,
// which is what `read_value` requires from us.
unsafe { read_value(self.target) }
}
}
/// Utilities to work with an array in progmem.
impl<T, const N: usize> ProgMem<[T; N]> {
/// Get a reference to an element from the array, without loading it.
///
/// # Panics
///
/// This method panics, if the given index `idx` is grater or equal to the
/// length `N` of the array.
pub fn at(&self, idx: usize) -> ProgMem<T> {
// Just use the slice impl
let slice: ProgMem<[T]> = self.as_slice();
slice.at(idx)
}
/// Iterate over all elements as wrappers.
///
/// Returns an iterator, which yields each element as a `ProgMem<T>`,
/// which can be subsequently loaded.
pub fn wrapper_iter(&self) -> PmWrapperIter<T> {
PmWrapperIter::new(self.as_slice())
}
/// Returns the length of the array (i.e. `N`)
pub fn len(&self) -> usize {
N
}
/// Coerce this array wrapper into a slice wrapper.
///
/// Notice, if you enable the "unsize" crate feature, you can directly
/// coerce the `ProgMem` struct, otherwise you have to use this function
/// instead.
///
/// This analog to normal Rust coercing of arrays to slices.
/// Indeed, if you enable the crate feature "unsize", you can use normal
/// Rust coercing to get the same result.
///
/// # Examples
///
/// ```rust
/// use avr_progmem::wrapper::ProgMem;
/// use avr_progmem::progmem;
///
/// progmem!{
/// static progmem ARR: [u8; 3] = [1,2,3];
/// }
///
/// // The array wrapper
/// let arr: ProgMem<[u8; 3]> = ARR;
/// // Coerced to a slice wrapper.
/// let s: ProgMem<[u8]> = arr.as_slice();
///
/// // If you enable the "unsize" crate feature, you can just coerce like that:
/// #[cfg(feature = "unsize")]
/// let s: ProgMem<[u8]> = arr;
/// ```
///
pub fn as_slice(&self) -> ProgMem<[T]> {
ProgMem {
target: self.target,
}
}
}
/// Loading elements of an array in progmem.
impl<T: Copy, const N: usize> ProgMem<[T; N]> {
/// Load a single element from the inner array.
///
/// This method is analog to a slice indexing `self.load()[idx]`, so the
/// same requirements apply, like the index `idx` should be less then the
/// length `N` of the array, otherwise a panic will be risen.
///
///
/// # Panics
///
/// This method panics, if the given index `idx` is grater or equal to the
/// length `N` of the inner type.
///
/// This method also panics, if the size of the value (i.e. `size_of::<T>()`)
/// is beyond 255 bytes.
/// However, this is currently just a implementation limitation, which may
/// be lifted in the future.
///
/// Notice, that here `T` is the type of the elements not the entire array
/// as it would be with [`load`](Self::load).
///
pub fn load_at(&self, idx: usize) -> T {
// Just get the element wrapper and load it
self.at(idx).load()
}
/// Loads a sub array from the inner array.
///
/// This method is analog to a sub-slicing `self.load()[idx..(idx+M)]` but
/// returning an owned array instead of a slice, simply because it has to
/// copy the data anyway from the progmem into the data domain (i.e. the
/// stack).
///
/// Also notice, that since this crate is intended for AVR
/// micro-controllers, static arrays are generally preferred over
/// dynamically allocated types such as a `Vec`.
///
///
/// # Panics
///
/// This method panics, if the given index `idx` is grater or equal to the
/// length `N` of the inner array, or the end index `idx+M` is grater than
/// the length `N` of the inner array.
///
/// This method also panics, if the size of the value
/// (i.e. `size_of::<[T;M]>()`) is beyond 255 bytes.
/// However, this is currently just a implementation limitation, which may
/// be lifted in the future.
///
pub fn load_sub_array<const M: usize>(&self, start_idx: usize) -> [T; M] {
// Just a check to give a nicer panic message
assert!(
M <= N,
"The sub array can not be grater than the source array"
);
// SAFETY: bounds check, the last element of the sub array must
// still be within the source array (i.e. self)
assert!(
start_idx + M <= N,
"The sub array goes beyond the end of the source array"
);
let first_source_element_ptr: *const T = self.target.cast();
// Get a point to the selected element
let first_output_element_ptr = first_source_element_ptr.wrapping_add(start_idx);
// Pointer into as sub array into the source
let sub_array_ptr: *const [T; M] = first_output_element_ptr.cast();
// SAFETY: This is safe, because the invariant of this struct demands
// that this value (i.e. self and thus also its inner value) are stored
// in the progmem domain, which is what `read_value` requires from us.
unsafe { read_value(sub_array_ptr) }
}
/// Lazily iterate over all elements
///
/// Returns an iterator which lazily loads the elements one at a time
/// from progmem.
/// This means this iterator can be used to access huge arrays while
/// only requiring `size_of::<T>()` amount of stack memory.
///
/// # Panics
///
/// The returned iterator will panic, if the size of an element (i.e. `size_of::<T>()`)
/// is beyond 255 bytes.
/// However, this is currently just a implementation limitation, which may
/// be lifted in the future.
///
/// Notice, that here `T` is the type of the elements not the entire array
/// as it would be with [`load`](Self::load).
///
pub fn iter(&self) -> PmIter<T, N> {
PmIter::new(self)
}
}
/// Utilities to work with an slice wrapper.
///
/// You can obtain a slice wrapper by coercing an array wrapper.
impl<T> ProgMem<[T]> {
/// Get a reference to an element from the array, without loading it.
///
/// # Panics
///
/// This method panics, if the given index `idx` is grater or equal to the
/// length of the slice.
pub fn at(&self, idx: usize) -> ProgMem<T> {
// SAFETY: check that `idx` is in bounds
assert!(idx < self.target.len(), "Given index is out of bounds");
let first_element_ptr: *const T = self.target.cast();
// Get a point to the selected element
let element_ptr = first_element_ptr.wrapping_add(idx);
// This sound, because `self.target` is in program domain and we checked
// above that `idx` is in bound, thus that element pointer is also
// valid and pointing into the program domain.
ProgMem {
target: element_ptr,
}
}
/// Iterate over all elements as wrappers.
///
/// Returns an iterator, which yields each element as a `ProgMem<T>`,
/// which can be subsequently loaded.
pub fn wrapper_iter(&self) -> PmWrapperIter<T> {
PmWrapperIter::new(*self)
}
/// Returns the length of the slice
pub fn len(&self) -> usize {
self.target.len()
}
}
/// Loading elements of an array in progmem.
impl<T: Copy> ProgMem<[T]> {
/// Load a single element from the slice.
///
/// This method is analog to a slice indexing, thus the same requirements
/// apply: the index `idx` should be less then the length of the slice,
/// otherwise a panic will be risen.
///
///
/// # Panics
///
/// This method panics, if the given index `idx` is grater or equal to the
/// length of the slice.
///
/// This method also panics, if the size of the value (i.e. `size_of::<T>()`)
/// is beyond 255 bytes.
/// However, this is currently just a implementation limitation, which may
/// be lifted in the future.
///
/// Notice, that here `T` is the type of the elements not the entire slice.
///
pub fn load_at(&self, idx: usize) -> T {
// Just get the element wrapper and load it
self.at(idx).load()
}
}
/// Allows coercing a `ProgMem<T>` to a `ProgMem<U>`, where U might be unsized.
///
/// A classic example of this is coercing an array `ProgMem<[T; N]>` into a
/// slice `ProgMem<[T]>`. Thus this impl is a generalization of the
/// [`as_slice`][ProgMem::as_slice] method.
///
/// # Examples
///
/// ```rust
/// use avr_progmem::wrapper::ProgMem;
/// use avr_progmem::progmem;
///
/// progmem!{
/// static progmem ARR: [u8; 3] = [1,2,3];
/// }
///
/// // The array wrapper
/// let arr: ProgMem<[u8; 3]> = ARR;
/// // Coerced to a slice wrapper, just like that.
/// let s: ProgMem<[u8]> = arr;
/// ```
#[cfg(feature = "unsize")]
impl<T: ?Sized, U: ?Sized> core::ops::CoerceUnsized<ProgMem<U>> for ProgMem<T> where
T: core::marker::Unsize<U>
{
}
/// An iterator over an array in progmem.
///
/// Can be acquired via [`ProgMem::iter`].
pub struct PmIter<'a, T, const N: usize> {
progmem: &'a ProgMem<[T; N]>,
current_idx: usize,
}
impl<'a, T, const N: usize> PmIter<'a, T, N> {
/// Creates a new iterator over the given progmem array.
pub const fn new(pm: &'a ProgMem<[T; N]>) -> Self {
Self {
progmem: pm,
current_idx: 0,
}
}
}
impl<'a, T: Copy, const N: usize> Iterator for PmIter<'a, T, N> {
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
// Check for iterator end
if self.current_idx < N {
// Load next item from progmem
let b = self.progmem.load_at(self.current_idx);
self.current_idx += 1;
Some(b)
} else {
None
}
}
}
/// Same as [`ProgMem::iter`]
impl<'a, T: Copy, const N: usize> IntoIterator for &'a ProgMem<[T; N]> {
type IntoIter = PmIter<'a, T, N>;
type Item = T;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
/// An iterator over an array in progmem, without loading elements
///
/// Can be acquired via [`ProgMem::wrapper_iter`].
pub struct PmWrapperIter<T> {
progmem: ProgMem<[T]>,
current_idx: usize,
}
impl<T> PmWrapperIter<T> {
/// Creates a new iterator over the given progmem array.
pub const fn new(pm: ProgMem<[T]>) -> Self {
Self {
progmem: pm,
current_idx: 0,
}
}
}
impl<T> Iterator for PmWrapperIter<T> {
type Item = ProgMem<T>;
fn next(&mut self) -> Option<Self::Item> {
// Check for iterator end
if self.current_idx < self.progmem.len() {
// Get next element wrapper
let b = self.progmem.at(self.current_idx);
self.current_idx += 1;
Some(b)
} else {
None
}
}
}
/// Define a static in progmem.
///
/// This is a helper macro to simplify the definition of statics that are valid
/// to be wrapped in the `ProgMem` struct thus providing a safe way to work
/// with data in progmem.
///
/// Thus this macro essentially takes a user static definition and emits a
/// definition that is defined to be stored in the progmem section and then is
/// wrap in the `ProgMem` wrapper for safe access.
///
/// There are essentially three types of statics that you can created:
///
/// * ordinary fixed-size data, e.g. a `u8`, `(u16,u32)`, or your own struct.
/// * "auto-sized" arrays, essentially any kind of array `[T; N]`
/// * strings, i.e. anything `str`-ish such as string literals
///
///
/// # Ordinary Data
///
/// You can store any `Copy + Sized` data in progmem and load it at your
/// leisure.
///
/// ## Example
///
/// ```
/// use avr_progmem::progmem;
///
/// #[derive(Copy, Clone)]
/// struct Foo {
/// a: u16,
/// b: u32,
/// }
///
/// progmem!{
/// /// Static data stored in progmem!
/// pub static progmem BYTE: u8 = b'a';
///
/// /// Anything that is `Copy + Sized`
/// pub static progmem FOO: Foo = Foo { a: 42, b: 42 * 42 };
/// }
///
/// // Loading the byte from progmem onto the stack
/// let data: u8 = BYTE.load();
/// assert_eq!(b'a', data);
///
/// // Loading the arbitrary data
/// let foo: Foo = FOO.load();
/// assert_eq!(42, foo.a);
/// assert_eq!(1764, foo.b);
/// ```
///
///
/// # Arrays
///
/// Notice, that to access ordinary data from the progmem you have to load it
/// as whole before you can do anything with it.
/// In other words you can't just load `foo.a`, you have to first load the
/// entire struct into RAM.
///
/// When we have arrays, stuff can get hugh quickly, therefore,
/// specifically for arrays, we have additionally accessors to access elements
/// individually, without the burden to load the entire array first.
///
/// ```
/// use avr_progmem::progmem;
///
/// progmem!{
/// /// A simple array using ordinary syntax
/// pub static progmem ARRAY: [u16; 4] = [1, 2, 3, 4];
/// }
///
/// // We can still load the entire array (but you shouldn't do this with
/// // big arrays)
/// let array: [u16; 4] = ARRAY.load();
/// assert_eq!([1,2,3,4], array);
///
/// // We can also load individual elements
/// let last_elem: u16 = ARRAY.load_at(3);
/// assert_eq!(4, last_elem);
///
/// // And even arbitrary sub-arrays (tho they need to be statically sized)
/// let middle_stuff: [u16; 2] = ARRAY.load_sub_array(1);
/// assert_eq!([2, 3], middle_stuff);
///
/// // Finally, we can iterate the array lazily loading one byte after another
/// // so we need only just enough RAM for to handle a single element
/// let mut elem_iter = ARRAY.iter();
/// assert_eq!(Some(1), elem_iter.next());
/// assert_eq!(Some(2), elem_iter.next());
/// assert_eq!(Some(3), elem_iter.next());
/// assert_eq!(Some(4), elem_iter.next());
/// assert_eq!(None, elem_iter.next());
/// ```
///
/// ## Auto-Sizing
///
/// While we could use arrays with the syntax from above, we get also use an
/// alternative syntax, where the array size is gets inferred which is
/// particularly useful if you include external data (e.g. form a file).
///
/// ```
/// use avr_progmem::progmem;
///
/// progmem!{
/// /// An "auto-sized" array (the size is inferred and made accessible by
/// /// a constant named `DATA_LEN`, tho any name would do)
/// pub static progmem<const DATA_LEN: usize> DATA: [u8; DATA_LEN] =
/// *include_bytes!("../examples/test_text.txt"); // assume it's binary
/// }
///
/// // "auto-sized" array can be accessed in the exactly same way as ordinary
/// // arrays, we just don't need to hardcode the size, and even get this nice
/// // constant at our disposal.
/// let middle: u8 = DATA.load_at(DATA_LEN / 2);
/// assert_eq!(32, middle);
/// ```
///
/// # Strings
///
/// Strings are complicated, partially, because in Rust strings such as `str`
/// are unsized making storing them a nightmare (normally the compiler somehow
/// manages to automagically put all your string literals into static memory,
/// but you can't have a `static` that stores a `str` by-value, that is without
/// the `&`).
/// The next best thing that one can do to store a "string" is to store some
/// fix-size array either of `char`s or of UTF-8 encoded `u8`s, which aren't
/// exactly `str` and thus much more cumbersome to use.
/// Therefore, this crate has dedicated an entire
/// [module to strings](crate::string).
///
/// Consequently, this macro also has some special syntax to make string
/// literals, which are given as some `&str` and are automagically converted
/// into something more manageable
/// (i.e. a [`PmString`](crate::string::PmString)) and are put in this format
/// into a progmem `static`.
///
/// ## Examples
///
/// ```rust
/// use avr_progmem::progmem;
///
/// progmem! {
/// /// A static string stored in program memory as a `PmString`.
/// /// Notice the `string` keyword.
/// static progmem string TEXT = "Unicode text: 大賢者";
/// }
///
/// let text = TEXT.load();
/// assert_eq!("Unicode text: 大賢者", &*text);
/// ```
///
#[macro_export]
macro_rules! progmem {
// Special string rule
(
$( #[ $attr:meta ] )*
$vis:vis static progmem string $name:ident = $value:expr ;
$($rest:tt)*
) => {
// Just forward to internal rule
$crate::progmem_internal!{
$(#[$attr])*
$vis static progmem string $name = $value ;
}
// Recursive call to allow multiple items in macro invocation
$crate::progmem!{
$($rest)*
}
};
// Catch "hand" strings rule, use the above special rule instead
(
$( #[ $attr:meta ] )*
$vis:vis static progmem $name:ident : $( avr_progmem::string:: )? LoadedString < $ty:literal > = $( avr_progmem::string:: )? LoadedString :: new ( $value:expr ) $( . unwrap () $(@ $unwrapped:ident)? )? ;
$($rest:tt)*
) => {
// Make this a hard compile-time error.
::core::compile_error!("Prefer using the special `PmString` rule with the `string` keyword.");
::core::compile_error!(concat!("Use instead: ", stringify!($vis), " static progmem string ", stringify!($name), " = ..."));
// Emit a dummy to suppress errors where `$name` is used
static $name : $crate::wrapper::ProgMem< $crate::string::LoadedString< $ty > > = todo!();
// Recursive call to allow multiple items in macro invocation
$crate::progmem!{
$($rest)*
}
};
// Catch references rule, reference are evil!
// (well actually they are not, but most likely using them *is* a mistake)
(
$( #[ $attr:meta ] )*
$vis:vis static progmem $name:ident : & $ty:ty = $value:expr ;
$($rest:tt)*
) => {
// Make this a hard compile-time error
::core::compile_error!("Do not use a reference type for progmem, because this way only the reference itself would be in progmem, whereas the underlying data would still be in the normal data domain!");
// Emit a dummy to suppress errors where `$name` is used
static $name : & $ty = todo!();
// Recursive call to allow multiple items in macro invocation
$crate::progmem!{
$($rest)*
}
};
// Standard rule
(
$( #[ $attr:meta ] )*
$vis:vis static progmem $( < const $size_name:ident : usize > )? $name:ident : $ty:ty = $value:expr ;
$($rest:tt)*
) => {
// Crate the progmem static via internal macro
$crate::progmem_internal!{
$(#[$attr])* $vis static progmem $( < const $size_name : usize > )? $name : $ty = $value;
}
// Recursive call to allow multiple items in macro invocation
$crate::progmem!{
$($rest)*
}
};
// Empty rule
() => ()
}
#[doc(hidden)]
pub const fn array_from_str<const N: usize>(s: &str) -> [u8; N] {
let array_ref = crate::string::from_slice::array_ref_try_from_slice(s.as_bytes());
match array_ref {
Ok(r) => *r,
Err(_) => panic!("Invalid array size"),
}
}
/// Only for internal use. Use the `progmem!` macro instead.
#[doc(hidden)]
#[macro_export]
macro_rules! progmem_internal {
// The string rule creating the progmem string static via `PmString`
{
$( #[ $attr:meta ] )*
$vis:vis static progmem string $name:ident = $value:expr ;
} => {
// User attributes
$(#[$attr])*
// The facade static definition, this only contains a pointer and thus
// is NOT in progmem, which in turn makes it safe & sound to access this
// facade.
$vis static $name: $crate::string::PmString<{
// This bit runs at compile-time
let s: &str = $value;
s.len()
}> = {
// This inner hidden static contains the actual real raw value.
//
// SAFETY: it must be stored in the progmem or text section!
// The `link_section` lets us define that:
#[cfg_attr(target_arch = "avr", link_section = ".progmem.data")]
static VALUE: [u8; {
// This bit runs at compile-time
let s: &str = $value;
s.len()
}] = $crate::wrapper::array_from_str( $value );
let pm = unsafe {
// SAFETY: This call is sound because we ensure with the above
// `link_section` attribute on `VALUE` that it is indeed
// in the progmem section.
$crate::wrapper::ProgMem::new(
::core::ptr::addr_of!(VALUE)
)
};
// Just return the PmString wrapper around the local static
unsafe {
// SAFETY: This call is sound, because we started out with a
// `&str` thus the conent of `VALUE` must be valid UTF-8
$crate::string::PmString::new(
pm
)
}
};
};
// The rule creating an auto-sized progmem static via `ProgMem`
{
$( #[ $attr:meta ] )*
$vis:vis static progmem < const $size_name:ident : usize > $name:ident : $ty:ty = $value:expr ;
} => {
// Create a constant with the size of the value, which is retrieved
// via `SizedOwned` on the value, assuming it is an array of sorts.
//#[doc = concat!("Size of [", stringify!( $name ))]
$vis const $size_name : usize = {
// This bit is a bit hacky, we just hope that the type of `$value`
// has some `len` method.
$value.len()
};
// Just a normal prgomem static, `$ty` may use the above constant
$crate::progmem_internal!{
$( #[ $attr ] )*
$vis static progmem $name : $ty = $value ;
}
};
// The normal rule creating a progmem static via `ProgMem`
{
$( #[ $attr:meta ] )*
$vis:vis static progmem $name:ident : $ty:ty = $value:expr ;
} => {
// User attributes
$(#[$attr])*
// The facade static definition, this only contains a pointer and thus
// is NOT in progmem, which in turn makes it safe & sound to access this
// facade.
$vis static $name: $crate::wrapper::ProgMem<$ty> = {
// This inner hidden static contains the actual real raw value.
//
// SAFETY: it must be stored in the progmem or text section!
// The `link_section` lets us define that:
#[cfg_attr(target_arch = "avr", link_section = ".progmem.data")]
static VALUE: $ty = $value;
unsafe {
// SAFETY: This call is sound because we ensure with the above
// `link_section` attribute on `VALUE` that it is indeed
// in the progmem section.
$crate::wrapper::ProgMem::new(
::core::ptr::addr_of!(VALUE)
)
}
};
};
}
/// ```compile_fail
/// use avr_progmem::progmem;
/// progmem! {
/// static progmem AREF: &str = "Sometext";
/// }
/// ```
#[cfg(doctest)]
pub struct ProgMemReferenceTest;
/// ```compile_fail
/// use avr_progmem::progmem;
/// progmem! {
/// // Should notify that we should use the `progmem string` rule instead
/// static progmem HAND_STRING: LoadedString<34> =
/// LoadedString::new("hand crafted progmem loaded string").unwrap();
/// }
/// ```
#[cfg(doctest)]
pub struct HandStringTest;