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//! # Bounded Registers //! //! A high-assurance memory-mapped register code generation and //! interaction library. //! //! ## Install //! //! ```not_rust //! $ git clone git@github.com:auxoncorp/registers.git //! $ cd registers && cargo install //! ``` //! //! ## Use //! //! There are two core pieces to `bounded-registers`: //! //! ### I. The macro //! //! ``` //! # #[macro_use] //! # extern crate bounded_registers; //! # #[macro_use] //! # extern crate typenum; //! register! { //! Status, //! u8, //! RW, //! Fields [ //! On WIDTH(U1) OFFSET(U0), //! Dead WIDTH(U1) OFFSET(U1), //! Color WIDTH(U3) OFFSET(U2) [ //! Red = U1, //! Blue = U2, //! Green = U3, //! Yellow = U4 //! ] //! ] //! } //! # fn main() {} //! ``` //! //! The `register!` macro generates the code necessary for ergonomic //! register access and manipulation. The expected input for the macro is //! as follows: //! 1. The register name. //! 1. Its numeric type. //! 1. Its mode, either `RO` (read only), `RW` (read write), or `WO` //! (write only). //! 1. The register's fields, beginning with `Fields [`, and then a //! closing `]` at the end. //! //! A field constists of its name, its width, and its offset within the //! register. Optionally, one may also state enum-like key/value pairs for //! the values of the field, nested within the field declaration with //! `[]`'s //! //! The code which this macro generates is a tree of nested modules where //! the root is a module called `$register_name`. Within `$register_name`, //! there will be the register itself, as `$register_name::Register`, as //! well as a child module for each field. //! //! Within each field module, one can find the field itself, as //! `$register_name::$field_name::Field`, as well as a few helpful aliases //! and constants. //! //! * `$register_name::$field_name::Read`: In order to read a field, an //! instance of that field must be given to have access to its mask and //! offset. `Read` can be used as an argument to `get_field` so one does //! not have to construct an arbitrary one when doing a read. //! * `$register_name::$field_name::Clear`: A field whose value is //! zero. Passing it to `modify` will clear that field in the register. //! * `$register_name::$field_name::Set`: A field whose value is //! `$field_max`. Passing it to `modify` will set that field to its max //! value in the register. This is useful particularly in the case of //! single-bit wide fields. //! * `$register_name::$field_name::$enum_kvs`: constants mapping the enum //! like field names to values. //! //! ### II. Interacting with registers //! //! #### Through a constructor //! //! ``` //! # #[macro_use] // register! leans on typenum's op! macro. //! # extern crate typenum; //! # #[macro_use] //! # extern crate bounded_registers; //! # register! { //! # Status, //! # u8, //! # RW, //! # Fields [ //! # On WIDTH(U1) OFFSET(U0), //! # Dead WIDTH(U1) OFFSET(U1), //! # Color WIDTH(U3) OFFSET(U2) [ //! # Red = U1, //! # Blue = U2, //! # Green = U3, //! # Yellow = U4 //! # ] //! # ] //! # } //! fn main() { //! let mut reg = Status::Register::new(0); //! reg.modify(Status::Dead::Set); //! assert_eq!(reg.read(), 2); //! } //! ``` //! //! In this example, we initialize a register with the value `0` and then //! set the `Dead` bit—the second field—which should produce the value `2` //! when interpreting this word-sized register as a `u32`. //! //! #### Through a register block //! //! Here we take a known address, one we may find in a developer's manual, //! and interpret that address as a register block. We can then //! dereference that pointer and use the register API to access the //! registers in the block. //! //! You can then implement `Deref` and `DerefMut` for a type which holds //! onto the address of such a register block. This fills in the gaps for //! method lookup (during typechecking) so that you can ergonomically use //! this type to interact with the register block: //! //! ``` //! #[macro_use] //! extern crate bounded_registers; //! #[macro_use] //! extern crate typenum; //! //! use core::ops::{Deref, DerefMut}; //! //! register! { //! UartRX, //! u32, //! RO, //! Fields [ //! Data WIDTH(U8) OFFSET(U0), //! ParityError WIDTH(U1) OFFSET(U10), //! Brk WIDTH(U1) OFFSET(U11), //! FrameError WIDTH(U1) OFFSET(U12), //! Overrrun WIDTH(U1) OFFSET(U13), //! Error WIDTH(U1) OFFSET(U14), //! ChrRdy WIDTH(U1) OFFSET(U15) //! ] //! } //! //! register! { //! UartTX, //! u32, //! WO, //! Fields [ //! Data WIDTH(U8) OFFSET(U0) //! ] //! } //! //! register! { //! UartControl1, //! u32, //! RW, //! Fields [ //! Enable WIDTH(U1) OFFSET(U0), //! Doze WIDTH(U1) OFFSET(U1), //! AgingDMATimerEnable WIDTH(U1) OFFSET(U2), //! TxRdyDMAENable WIDTH(U1) OFFSET(U3), //! SendBreak WIDTH(U1) OFFSET(U4), //! RTSDeltaInterrupt WIDTH(U1) OFFSET(U5), //! TxEmptyInterrupt WIDTH(U1) OFFSET(U6), //! Infrared WIDTH(U1) OFFSET(U7), //! RecvReadyDMA WIDTH(U1) OFFSET(U8), //! RecvReadyInterrupt WIDTH(U1) OFFSET(U9), //! IdleCondition WIDTH(U2) OFFSET(U10), //! IdleInterrupt WIDTH(U1) OFFSET(U12), //! TxReadyInterrupt WIDTH(U1) OFFSET(U13), //! AutoBaud WIDTH(U1) OFFSET(U14), //! AutoBaudInterrupt WIDTH(U1) OFFSET(U15) //! ] //! } //! //! #[repr(C)] //! pub struct UartBlock { //! rx: UartRX::Register, //! _padding1: [u32; 15], //! tx: UartTX::Register, //! _padding2: [u32; 15], //! control1: UartControl1::Register, //! } //! //! pub struct Regs { //! addr: usize, //! } //! //! impl Deref for Regs { //! type Target = UartBlock; //! //! fn deref(&self) -> &UartBlock { //! unsafe { &*(self.addr as *const UartBlock) } //! } //! } //! //! impl DerefMut for Regs { //! fn deref_mut(&mut self) -> &mut UartBlock { //! unsafe { &mut *(self.addr as *mut UartBlock) } //! } //! } //! //! fn main() { //! let mut x = [0_u32; 33]; //! let mut regs = Regs { //! // Some shenanigans to get at `x` as though it were a //! // pointer. Normally you'd be given some address like //! // `0xDEADBEEF` over which you'd instantiate a `Regs`. //! addr: &mut x as *mut [u32; 33] as usize, //! }; //! //! assert_eq!(regs.rx.read(), 0); //! regs.control1 //! .modify(UartControl1::Enable::Set + UartControl1::RecvReadyInterrupt::Set); //! //! // The first bit and the 10th bit should be set. //! assert_eq!(regs.control1.read(), 0b_10_0000_0001); //! } //! ``` //! //! # The Register API //! //! The register API code is generated with docs, but you'll have to build //! the rustdoc documentation for your library that uses //! `bounded-registers` to be able to see it. For convenience, I've //! extrapolated it here: //! //! ``` //! # extern crate bounded_registers; //! # extern crate typenum; //! # use bounded_registers::*; //! # use bounded_registers::bounds::*; //! # use typenum::*; //! # type Width = u8; //! # struct Register; //! # trait R { //! /// `new` constructs a read-write register around the //! /// given pointer. //! fn new(init: Width) -> Self; //! //! /// `get_field` takes a field and sets the value of that //! /// field to its value in the register. //! fn get_field<M: Unsigned, O: Unsigned, U: Unsigned>( //! &self, //! f: Field<Width, M, O, U, Register>, //! ) -> Option<Field<Width, M, O, U, Register>> //! where //! U: IsGreater<U0, Output = True> + ReifyTo<Width>, //! M: ReifyTo<Width>, //! O: ReifyTo<Width>, //! U0: ReifyTo<Width>; //! //! /// `read` returns the current state of the register as a `Width`. //! fn read(&self) -> Width; //! //! /// `extract` pulls the state of a register out into a wrapped //! /// read-only register. //! fn extract(&self) -> ReadOnlyCopy<Width, Register>; //! //! /// `is_set` takes a field and returns true if that field's value //! /// is equal to its upper bound or not. This is of particular use //! /// in single-bit fields. //! fn is_set<M: Unsigned, O: Unsigned, U: Unsigned>( //! &self, //! f: Field<Width, M, O, U, Register>, //! ) -> bool //! where //! U: IsGreater<U0, Output = True>, //! U: ReifyTo<Width>, //! M: ReifyTo<Width>, //! O: ReifyTo<Width>; //! //! // `Positioned` is a special trait that all fields implement, as //! // well as a type used as an accumulator when reading from or //! // writing to multiple fields. To use these functions with //! // multiple fields, join them together with `+`. An `Add` //! // implementation for fields has been provided for this purpose. //! //! /// `matches_any` returns whether or not any of the given fields //! /// match those fields values inside the register. //! fn matches_any<V: Positioned<Width = Width>>(&self, val: V) -> bool; //! //! /// `matches_all` returns whether or not all of the given fields //! /// match those fields values inside the register. //! fn matches_all<V: Positioned<Width = Width>>(&self, val: V) -> bool; //! //! /// `modify` takes one or more fields, joined by `+`, and //! /// sets those fields in the register, leaving the others //! /// as they were. //! fn modify<V: Positioned<Width = Width>>(&mut self, val: V); //! //! /// `write` sets the value of the whole register to the //! /// given `Width` value. //! fn write(&mut self, val: Width); //! # } //! # fn main() {} //! ``` //! //! ## Theory //! //! `bounded-registers` employs values—specifically numbers—at the //! type-level in order to get compile time assertions on interactions //! with a register. Each field's width is used to determine a maximum //! value, and then reading from and writing to those fields is either //! checked at compile time, through the `checked` function, or is //! expected to _carry_ a proof, which uses the aforementioned bound //! to construct a value at runtime which is known to not contravene //! it. #![no_std] #![feature(const_fn)] #[allow(unused)] #[macro_use] extern crate typenum; pub mod bounds; pub mod macros; mod register; pub use crate::register::*;