1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339
//! Provides macros to support bitfield structs allowing for modular use of bit-enums. //! //! The mainly provided macros are `#[bitfield]` for structs and //! `#[derive(BitfieldSpecifier)]` for enums that shall be usable //! within bitfield structs. //! //! There are preset bitfield specifiers such as `B1`, `B2`,..,`B64` //! that allow for easy bitfield usage in structs very similar to how //! they work in C or C++. //! //! - Performance of the macro generated code is as fast as its hand-written //! alternative. //! - Compile-time checks allow for safe usage of bitfield structs and enums. //! //! ### Showcase //! //! ``` //! use modular_bitfield::prelude::*; //! //! // Works with aliases - just for the showcase. //! type Vitamin = B12; //! //! /// Bitfield struct with 32 bits in total. //! #[bitfield] //! pub struct Example { //! a: bool, // Uses 1 bit //! b: B9, // Uses 9 bits //! c: Vitamin, // Uses 12 bits, works with aliases. //! #[bits = 3] // Optional, asserts at compiletime that `DeliveryMode` uses 3 bits. //! d: DeliveryMode, // Uses 3 bits //! e: B7, // Uses 7 bits //! } //! //! /// Enums that derive from `BitfieldSpecifier` //! /// can also be used within bitfield structs //! /// as shown above. //! #[derive(BitfieldSpecifier, Debug, PartialEq)] //! pub enum DeliveryMode { //! Fixed = 1, //! Lowest, //! SMI, //! RemoteRead, //! NMI, //! Init = 0, //! Startup = 6, //! External, //! } //! //! fn it_works() { //! let mut example = Example::new(); //! //! // Assert that everything is inizialized to 0. //! assert_eq!(example.get_a(), false); //! assert_eq!(example.get_b(), 0); //! assert_eq!(example.get_c(), 0); //! assert_eq!(example.get_d(), DeliveryMode::Init); //! assert_eq!(example.get_e(), 0); //! //! // Modify the bitfields. //! example.set_a(true); //! example.set_b(0b0001_1111_1111_u16); // Uses `u16` //! example.set_c(42_u16); // Uses `u16` //! example.set_d(DeliveryMode::Startup); //! example.set_e(1); // Uses `u8` //! //! // Assert the previous modifications. //! assert_eq!(example.get_a(), true); //! assert_eq!(example.get_b(), 0b0001_1111_1111_u16); //! assert_eq!(example.get_c(), 42); //! assert_eq!(example.get_d(), DeliveryMode::Startup); //! assert_eq!(example.get_e(), 1_u8); //! } //! ``` //! //! ## Generated Structure //! //! From David Tolnay's procedural macro workshop: //! //! The macro conceptualizes given structs as a sequence of bits 0..N. //! The bits are grouped into fields in the order specified by the struct written by the user. //! //! The `#[bitfield]` attribute rewrites the caller's struct into a private byte array representation //! with public getter and setter methods for each field. //! The total number of bits N is required to be a multiple of 8: This is checked at compile time. //! //! ### Example //! //! The following invocation builds a struct with a total size of 32 bits or 4 bytes. //! It places field `a` in the least significant bit of the first byte, //! field `b` in the next three least significant bits, //! field `c` in the remaining four most significant bits of the first byte, //! and field `d` spanning the next three bytes. //! //! ```rust //! use modular_bitfield::prelude::*; //! //! #[bitfield] //! pub struct MyFourBytes { //! a: B1, //! b: B3, //! c: B4, //! d: B24, //! } //! ``` //! ```no_compile //! least significant bit of third byte //! ┊ most significant //! ┊ ┊ //! ┊ ┊ //! ║ first byte ║ second byte ║ third byte ║ fourth byte ║ //! ╟───────────────╫───────────────╫───────────────╫───────────────╢ //! ║▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒║ //! ╟─╫─────╫───────╫───────────────────────────────────────────────╢ //! ║a║ b ║ c ║ d ║ //! ┊ ┊ //! ┊ ┊ //! least significant bit of d most significant //! ``` pub use modular_bitfield_impl::{ bitfield, BitfieldSpecifier, }; /// Preset check types and traits used internally. /// /// # Note /// /// Do not use entities defined in here directly! #[doc(hidden)] pub mod checks; /// The prelude: `use modular_bitfield::prelude::*;` pub mod prelude { pub use super::{ specifiers::*, PopBits, PushBits, bitfield, BitfieldSpecifier, Specifier, SpecifierBase, IntoBits, FromBits, }; } /// The default set of predefined specifiers. pub mod specifiers { modular_bitfield_impl::define_specifiers!(); } /// Helper trait for underlying primitives handling of bitfields. /// /// # Note /// /// Must not and cannot be implemented by dependencies. #[doc(hidden)] pub trait PushBits: checks::private::Sealed { fn push_bits(&mut self, amount: u32, bits: u8); } /// Helper trait for underlying primitives handling of bitfields. /// /// # Note /// /// Must not and cannot be implemented by dependencies. #[doc(hidden)] pub trait PopBits: checks::private::Sealed { fn pop_bits(&mut self, amount: u32) -> u8; } macro_rules! impl_sealed_for { ( $($primitive:ty),* ) => { $( impl checks::private::Sealed for $primitive {} )* } } impl_sealed_for!(bool, u8, u16, u32, u64, u128); impl PopBits for u8 { #[inline(always)] fn pop_bits(&mut self, amount: u32) -> u8 { debug_assert!(amount <= 8); let res = *self & ((0x1_u16.wrapping_shl(amount) as u8).wrapping_sub(1)); *self = self.wrapping_shr(amount); res } } macro_rules! impl_push_bits { ( $($type:ty),+ ) => { $( impl PushBits for $type { #[inline(always)] fn push_bits(&mut self, amount: u32, bits: u8) { debug_assert!(amount <= 8); *self <<= amount; *self |= (bits & ((0x1_u16.wrapping_shl(amount) as u8).wrapping_sub(1))) as $type; } } )+ } } impl_push_bits!(u8, u16, u32, u64, u128); macro_rules! impl_pop_bits { ( $($type:ty),+ ) => { $( impl PopBits for $type { #[inline(always)] fn pop_bits(&mut self, amount: u32) -> u8 { debug_assert!(amount <= 8); let res = (*self & ((0x1 << amount) - 1)) as u8; *self >>= amount; res } } )+ }; } impl_pop_bits!(u16, u32, u64, u128); /// Trait implemented by primitives that drive bitfield manipulations generically. #[doc(hidden)] pub trait SpecifierBase: checks::private::Sealed { /// The base type that the specifier is operating on. type Base; } /// Trait implemented by all bitfield specifiers. /// /// Should generally not be implemented directly by users /// but through the macros provided by the crate. /// /// # Note /// /// These can be all unsigned fixed-size primitives, /// represented by `B1, B2, ... B64` and enums that /// derive from `BitfieldSpecifier`. pub trait Specifier { /// The amount of bits used by the specifier. const BITS: usize; /// The base type of the specifier. /// /// # Note /// /// This is the type that is used internally for computations. type Base: Default + PushBits + PopBits; /// The interface type of the specifier. /// /// # Note /// /// This is the type that is used for the getters and setters. type Face: FromBits<Self::Base> + IntoBits<Self::Base>; } /// Helper struct to convert primitives and enum discriminants. #[doc(hidden)] pub struct Bits<T>(pub T); impl<T> Bits<T> { /// Returns the raw underlying representation. #[inline(always)] pub fn into_raw(self) -> T { self.0 } } /// Helper trait to convert to bits. /// /// # Note /// /// Implemented by primitive specifier types. #[doc(hidden)] pub trait IntoBits<T> { fn into_bits(self) -> Bits<T>; } /// Helper trait to convert from bits. /// /// # Note /// /// Implemented by primitive specifier types. #[doc(hidden)] pub trait FromBits<T> { fn from_bits(bits: Bits<T>) -> Self; } impl Specifier for bool { const BITS: usize = 1; type Base = u8; type Face = bool; } impl FromBits<u8> for bool { #[inline(always)] fn from_bits(bits: Bits<u8>) -> Self { bits.into_raw() != 0 } } impl IntoBits<u8> for bool { #[inline(always)] fn into_bits(self) -> Bits<u8> { Bits(self as u8) } } macro_rules! impl_wrapper_from_naive { ( $($type:ty),* ) => { $( impl IntoBits<$type> for $type { #[inline(always)] fn into_bits(self) -> Bits<$type> { Bits(self) } } impl FromBits<$type> for $type { #[inline(always)] fn from_bits(bits: Bits<$type>) -> Self { bits.into_raw() } } )* } } impl_wrapper_from_naive!(bool, u8, u16, u32, u64, u128);