General

Libraries

File - Struct defined in std::fs

Keywords

mut - Mutable, variable can be changed after initially set. Variables are immutable by default. Indicating mutability helps prevent bugs at compile time

&mut - Create mutable reference to a value, whether or not variable can be reassigned.

Types

Option<T> - All types are either Some(T) (an element of type T exists) or N (No element of type T exists)

Result<T,E> - Similar to option, but takes in result of computation. Can output either Ok(T) (success) or Err(E) (fail)

Methods

.unwrap() - Can be called on Option or Result type. If Option is None or Result is Err(E), then the program will panic

Traits

#![feature(never_type)] - Indicating that the function will never return

Other Weird things

• ! delineates macros and not functions
• Adding b at the beginning of a println or stdout, makes your output a byte string instead of a Unicode scalar value. Most of the time this doesn't super matter as long as you are consistent, but u8 values can be preferred because they are always 8 bits, vs Unicode scalar values can be up to 32 bits
• usize used for any indices
• If you don't use & when referencing a value, you are taking ownership of it

Embedded Systems

General Information

• #![no_std] and #![no_main] aren't available, use libcore instead

  • Still have access to primitive types (u8, i32, f64), string slices, time, arrays, and iterators
  • Not pulling in other libraries at least means compile times are fast

• You usually don't have memory allocation, your code is the only thing running

• No threads, no networking, no std::fs

• Using generic HALs to apply functionality to known characteristics like Input and Output, and then using chip specific libraries to plug into generic HAL for interoperability

• Within USBs, there are different classes. Eg for keyboards it is the HID (Human Interface Device) class