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//! Bit-level packing and unpacking for Rust //! =========================================== //! //! [](https://travis-ci.org/hashmismatch/packed_struct.rs) //! //! [](https://docs.rs/packed_struct) //! //! # Introduction //! //! Packing and unpacking bit-level structures is usually a programming tasks that needlessly reinvents the wheel. This library provides //! a meta-programming approach, using attributes to define fields and how they should be packed. The resulting trait implementations //! provide safe packing, unpacking and runtime debugging formatters with per-field documentation generated for each structure. //! //! # Features //! //! * Plain Rust structures, decorated with attributes //! * MSB or LSB integers of user-defined bit widths //! * Primitive enum code generation helper //! * MSB0 or LSB0 bit positioning //! * Documents the field's packing table //! * Runtime packing visualization //! * Nested packed types //! * Arrays of packed structures as fields //! * Reserved fields, their bits are always 0 or 1 //! //! # Sample usage //! //! ## Cargo.toml //! //! ```toml //! [dependencies] //! packed_struct = "0.3" //! packed_struct_codegen = "0.3" //! ``` //! ## Including the library and the code generator //! //! ```rust //! extern crate packed_struct; //! #[macro_use] //! extern crate packed_struct_codegen; //! # fn main() { //! # } //! ``` //! //! ## Example of a single-byte structure, with a 3 bit integer, primitive enum and a bool field. //! //! ```rust //! extern crate packed_struct; //! #[macro_use] extern crate packed_struct_codegen; //! //! use packed_struct::prelude::*; //! //! #[derive(PackedStruct)] //! #[packed_struct(bit_numbering="msb0")] //! pub struct TestPack { //! #[packed_field(bits="0..=2")] //! tiny_int: Integer<u8, packed_bits::Bits3>, //! #[packed_field(bits="3..=4", ty="enum")] //! mode: SelfTestMode, //! #[packed_field(bits="7")] //! enabled: bool //! } //! //! #[derive(PrimitiveEnum_u8, Clone, Copy, Debug, PartialEq)] //! pub enum SelfTestMode { //! NormalMode = 0, //! PositiveSignSelfTest = 1, //! NegativeSignSelfTest = 2, //! DebugMode = 3, //! } //! //! fn main() { //! let test = TestPack { //! tiny_int: 5.into(), //! mode: SelfTestMode::DebugMode, //! enabled: true //! }; //! //! let packed = test.pack(); //! assert_eq!([0b10111001], packed); //! //! let unpacked = TestPack::unpack(&packed).unwrap(); //! assert_eq!(*unpacked.tiny_int, 5); //! assert_eq!(unpacked.mode, SelfTestMode::DebugMode); //! assert_eq!(unpacked.enabled, true); //! } //! ``` //! //! # Packing attributes //! //! ## Syntax //! //! ```rust //! extern crate packed_struct; //! #[macro_use] extern crate packed_struct_codegen; //! //! #[derive(PackedStruct)] //! #[packed_struct(attr1="val", attr2="val")] //! pub struct Structure { //! #[packed_field(attr1="val", attr2="val")] //! field: u8 //! } //! # fn main() { //! # } //! ``` //! //! ## Per-structure attributes //! //! Attribute | Values | Comment //! :--|:--|:-- //! ```size_bytes``` | ```1``` ... n | Size of the packed byte stream //! ```bit_numbering``` | ```msb0``` or ```lsb0``` | Bit numbering for bit positioning of fields. Required if the bits attribute field is used. //! ```endian``` | ```msb``` or ```lsb``` | Default integer endianness //! //! ## Per-field attributes //! //! Attribute | Values | Comment //! :--|:--|:-- //! ```bits``` | ```0```, ```0..1```, ... | Position of the field in the packed structure. Three modes are supported: a single bit, the starting bit, or a range of bits. See details below. //! ```bytes``` | ```0```, ```0..1```, ... | Same as above, multiplied by 8. //! ```size_bits``` | ```1```, ... | Specifies the size of the packed structure. Mandatory for certain types. Specifying a range of bits like ```bits="0..2"``` can substite the required usage of ```size_bits```. //! ```size_bytes``` | ```1```, ... | Same as above, multiplied by 8. //! ```element_size_bits``` | ```1```, ... | For packed arrays, specifies the size of a single element of the array. Explicitly stating the size of the entire array can substite the usage of this attribute. //! ```element_size_bytes``` | ```1```, ... | Same as above, multiplied by 8. //! ```ty``` | ```enum``` | Packing helper for primitive enums. //! ```endian``` | ```msb``` or ```lsb``` | Integer endianness. Applies to u16/i16 and larger types. //! //! ## Bit and byte positioning //! //! Used for either ```bits``` or ```bytes``` on fields. The examples are for MSB0 positioning. //! //! Value | Comment //! :--|:-- //! ```0``` | A single bit or byte //! ```0..```, ```0:``` | The field starts at bit zero //! ```0..2``` | Exclusive range, bits zero and one //! ```0:1```, ```0..=1``` | Inclusive range, bits zero and one //! //! # More examples //! //! ## Mixed endian integers //! //! ```rust //! extern crate packed_struct; //! #[macro_use] extern crate packed_struct_codegen; //! //! use packed_struct::prelude::*; //! //! #[derive(PackedStruct)] //! pub struct EndianExample { //! #[packed_field(endian="lsb")] //! int1: u16, //! #[packed_field(endian="msb")] //! int2: i32 //! } //! //! fn main() { //! let example = EndianExample { //! int1: 0xBBAA, //! int2: 0x11223344 //! }; //! //! let packed = example.pack(); //! assert_eq!([0xAA, 0xBB, 0x11, 0x22, 0x33, 0x44], packed); //! } //! ``` //! //! ## 24 bit LSB integers //! //! ```rust //! extern crate packed_struct; //! #[macro_use] extern crate packed_struct_codegen; //! //! use packed_struct::prelude::*; //! //! #[derive(PackedStruct)] //! #[packed_struct(endian="lsb")] //! pub struct LsbIntExample { //! int1: Integer<u32, packed_bits::Bits24>, //! } //! //! fn main() { //! let example = LsbIntExample { //! int1: 0xCCBBAA.into() //! }; //! //! let packed = example.pack(); //! assert_eq!([0xAA, 0xBB, 0xCC], packed); //! } //! ``` //! //! ## Nested packed types within arrays //! //! ```rust //! extern crate packed_struct; //! #[macro_use] extern crate packed_struct_codegen; //! //! use packed_struct::prelude::*; //! //! #[derive(PackedStruct, Default, Debug, PartialEq)] //! #[packed_struct(bit_numbering="msb0")] //! pub struct TinyFlags { //! _reserved: ReservedZero<packed_bits::Bits4>, //! flag1: bool, //! val1: Integer<u8, packed_bits::Bits2>, //! flag2: bool //! } //! //! #[derive(PackedStruct, Debug, PartialEq)] //! pub struct Settings { //! #[packed_field(element_size_bits="4")] //! values: [TinyFlags; 4] //! } //! //! fn main() { //! let example = Settings { //! values: [ //! TinyFlags { flag1: true, val1: 1.into(), flag2: false, .. TinyFlags::default() }, //! TinyFlags { flag1: true, val1: 2.into(), flag2: true, .. TinyFlags::default() }, //! TinyFlags { flag1: false, val1: 3.into(), flag2: false, .. TinyFlags::default() }, //! TinyFlags { flag1: true, val1: 0.into(), flag2: false, .. TinyFlags::default() }, //! ] //! }; //! //! let packed = example.pack(); //! let unpacked = Settings::unpack(&packed).unwrap(); //! //! assert_eq!(example, unpacked); //! } //! ``` //! //! # Primitive enums with simple discriminants //! //! Supported backing integer types: ```u8```, ```u16```, ```u32```, ```u64```, ```i8```, ```i16```, ```i32```, ```i64```. //! //! Explicit or implicit backing type: //! //! ```rust //! extern crate packed_struct; //! #[macro_use] extern crate packed_struct_codegen; //! //! #[derive(PrimitiveEnum, Clone, Copy)] //! pub enum ImplicitType { //! VariantMin = 0, //! VariantMax = 255 //! } //! //! #[derive(PrimitiveEnum_i16, Clone, Copy)] //! pub enum ExplicitType { //! VariantMin = -32768, //! VariantMax = 32767 //! } //! //! # fn main() {} //! ``` //! //! # Primitive enum packing with support for catch-all unknown values //! //! ```rust //! # use packed_struct::prelude::*; //! extern crate packed_struct; //! #[macro_use] extern crate packed_struct_codegen; //! //! #[derive(PrimitiveEnum_u8, Debug, Clone, Copy)] //! pub enum Field { //! A = 1, //! B = 2, //! C = 3 //! } //! //! #[derive(PackedStruct, Debug, PartialEq)] //! #[packed_struct(bit_numbering="msb0")] //! pub struct Register { //! #[packed_field(bits="0..4", ty="enum")] //! field: EnumCatchAll<Field> //! } //! //! # fn main() {} //! ``` #![cfg_attr(not(feature = "std"), no_std)] #![cfg_attr(feature="alloc", feature(alloc))] #[cfg(feature="alloc")] #[macro_use] extern crate alloc; extern crate serde; #[macro_use] extern crate serde_derive; mod internal_prelude; #[macro_use] mod packing; mod primitive_enum; pub use primitive_enum::*; #[cfg(any(feature="alloc", feature="std"))] pub mod debug_fmt; mod types_array; mod types_basic; mod types_bits; mod types_num; mod types_reserved; /// Implementations and wrappers for various packing types. pub mod types { pub use super::types_basic::*; /// Types that specify the exact number of bits a packed integer should occupy. pub mod bits { pub use super::super::types_bits::*; } pub use super::types_num::*; pub use super::types_array::*; pub use super::types_reserved::*; } pub use self::packing::*; pub mod prelude { //! Re-exports the most useful traits and types. Meant to be glob imported. pub use PackedStruct; pub use PackedStructSlice; pub use PackingError; pub use PrimitiveEnum; #[cfg(any(feature="alloc", feature="std"))] pub use PrimitiveEnumDynamicStr; #[cfg(not(any(feature="alloc", feature="std")))] pub use PrimitiveEnumStaticStr; pub use EnumCatchAll; pub use types::*; pub use types::bits as packed_bits; }