| 1 | //! Port of LLVM's APFloat software floating-point implementation from the |
| 2 | //! following C++ sources (please update commit hash when backporting): |
| 3 | //! <https://github.com/llvm/llvm-project/commit/462a31f5a5abb905869ea93cc49b096079b11aa4> |
| 4 | //! * `llvm/include/llvm/ADT/APFloat.h` -> `Float` and `FloatConvert` traits |
| 5 | //! * `llvm/lib/Support/APFloat.cpp` -> `ieee` and `ppc` modules |
| 6 | //! * `llvm/unittests/ADT/APFloatTest.cpp` -> `tests` directory |
| 7 | //! |
| 8 | //! The port contains no unsafe code, global state, or side-effects in general, |
| 9 | //! and the only allocations are in the conversion to/from decimal strings. |
| 10 | //! |
| 11 | //! Most of the API and the testcases are intact in some form or another, |
| 12 | //! with some ergonomic changes, such as idiomatic short names, returning |
| 13 | //! new values instead of mutating the receiver, and having separate method |
| 14 | //! variants that take a non-default rounding mode (with the suffix `_r`). |
| 15 | //! Comments have been preserved where possible, only slightly adapted. |
| 16 | //! |
| 17 | //! Instead of keeping a pointer to a configuration struct and inspecting it |
| 18 | //! dynamically on every operation, types (e.g. `ieee::Double`), traits |
| 19 | //! (e.g. `ieee::Semantics`) and associated constants are employed for |
| 20 | //! increased type safety and performance. |
| 21 | //! |
| 22 | //! On-heap bigints are replaced everywhere (except in decimal conversion), |
| 23 | //! with short arrays of `type Limb = u128` elements (instead of `u64`), |
| 24 | //! This allows fitting the largest supported significands in one integer |
| 25 | //! (`ieee::Quad` and `ppc::Fallback` use slightly less than 128 bits). |
| 26 | //! All of the functions in the `ieee::sig` module operate on slices. |
| 27 | //! |
| 28 | //! # Note |
| 29 | //! |
| 30 | //! This API is completely unstable and subject to change. |
| 31 | |
| 32 | #![no_std ] |
| 33 | #![deny (warnings)] |
| 34 | #![forbid (unsafe_code)] |
| 35 | |
| 36 | #[macro_use ] |
| 37 | extern crate bitflags; |
| 38 | |
| 39 | extern crate alloc; |
| 40 | |
| 41 | use core::cmp::Ordering; |
| 42 | use core::fmt; |
| 43 | use core::ops::{Add, Div, Mul, Neg, Rem, Sub}; |
| 44 | use core::ops::{AddAssign, DivAssign, MulAssign, RemAssign, SubAssign}; |
| 45 | use core::str::FromStr; |
| 46 | |
| 47 | bitflags! { |
| 48 | /// IEEE-754R 7: Default exception handling. |
| 49 | /// |
| 50 | /// UNDERFLOW or OVERFLOW are always returned or-ed with INEXACT. |
| 51 | /// |
| 52 | /// APFloat models this behavior specified by IEEE-754: |
| 53 | /// "For operations producing results in floating-point format, the default |
| 54 | /// result of an operation that signals the invalid operation exception |
| 55 | /// shall be a quiet NaN." |
| 56 | #[must_use ] |
| 57 | #[derive (Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)] |
| 58 | pub struct Status: u8 { |
| 59 | const OK = 0x00; |
| 60 | const INVALID_OP = 0x01; |
| 61 | const DIV_BY_ZERO = 0x02; |
| 62 | const OVERFLOW = 0x04; |
| 63 | const UNDERFLOW = 0x08; |
| 64 | const INEXACT = 0x10; |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | /// The result of a computation consisting of the output value and the exceptions, if any. |
| 69 | #[must_use ] |
| 70 | #[derive (Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)] |
| 71 | pub struct StatusAnd<T> { |
| 72 | pub status: Status, |
| 73 | pub value: T, |
| 74 | } |
| 75 | |
| 76 | impl Status { |
| 77 | /// Add a value to this status to create a [`StatusAnd`]. |
| 78 | pub fn and<T>(self, value: T) -> StatusAnd<T> { |
| 79 | StatusAnd { status: self, value } |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | impl<T> StatusAnd<T> { |
| 84 | /// Keep the existing status but apply a transformation to `value`. |
| 85 | pub fn map<F: FnOnce(T) -> U, U>(self, f: F) -> StatusAnd<U> { |
| 86 | StatusAnd { |
| 87 | status: self.status, |
| 88 | value: f(self.value), |
| 89 | } |
| 90 | } |
| 91 | } |
| 92 | |
| 93 | impl<T: core::fmt::Debug> StatusAnd<T> { |
| 94 | /// Extract the inner value if there were no errors. If there were errors, panic. |
| 95 | pub fn unwrap(self) -> T { |
| 96 | assert_eq!(self.status, Status::OK, "called `StatusAnd::unwrap()` on an error value. Value: {:?}" , self.value); |
| 97 | self.value |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | #[macro_export ] |
| 102 | macro_rules! unpack { |
| 103 | ($status:ident|=, $e:expr) => { |
| 104 | match $e { |
| 105 | $crate::StatusAnd { status, value } => { |
| 106 | $status |= status; |
| 107 | value |
| 108 | } |
| 109 | } |
| 110 | }; |
| 111 | ($status:ident=, $e:expr) => { |
| 112 | match $e { |
| 113 | $crate::StatusAnd { status, value } => { |
| 114 | $status = status; |
| 115 | value |
| 116 | } |
| 117 | } |
| 118 | }; |
| 119 | } |
| 120 | |
| 121 | /// Category of internally-represented number. |
| 122 | #[derive (Copy, Clone, PartialEq, Eq, Debug)] |
| 123 | pub enum Category { |
| 124 | Infinity, |
| 125 | NaN, |
| 126 | Normal, |
| 127 | Zero, |
| 128 | } |
| 129 | |
| 130 | /// IEEE-754R 4.3: Rounding-direction attributes. |
| 131 | #[derive (Copy, Clone, PartialEq, Eq, Debug)] |
| 132 | pub enum Round { |
| 133 | NearestTiesToEven, |
| 134 | TowardPositive, |
| 135 | TowardNegative, |
| 136 | TowardZero, |
| 137 | NearestTiesToAway, |
| 138 | } |
| 139 | |
| 140 | impl Neg for Round { |
| 141 | type Output = Round; |
| 142 | #[inline ] |
| 143 | fn neg(self) -> Round { |
| 144 | match self { |
| 145 | Round::TowardPositive => Round::TowardNegative, |
| 146 | Round::TowardNegative => Round::TowardPositive, |
| 147 | Round::NearestTiesToEven | Round::TowardZero | Round::NearestTiesToAway => self, |
| 148 | } |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | /// A signed type to represent a floating point number's unbiased exponent. |
| 153 | pub type ExpInt = i32; |
| 154 | |
| 155 | // \c ilogb error results. |
| 156 | pub const IEK_INF: ExpInt = ExpInt::max_value(); |
| 157 | pub const IEK_NAN: ExpInt = ExpInt::min_value(); |
| 158 | pub const IEK_ZERO: ExpInt = ExpInt::min_value() + 1; |
| 159 | |
| 160 | /// An error which can occur when parsing a floating point number from a string. |
| 161 | #[derive (Copy, Clone, PartialEq, Eq, Debug)] |
| 162 | pub struct ParseError(pub &'static str); |
| 163 | |
| 164 | /// A self-contained host- and target-independent arbitrary-precision |
| 165 | /// floating-point software implementation. |
| 166 | /// |
| 167 | /// `apfloat` uses significand bignum integer arithmetic as provided by functions |
| 168 | /// in the `ieee::sig`. |
| 169 | /// |
| 170 | /// Written for clarity rather than speed, in particular with a view to use in |
| 171 | /// the front-end of a cross compiler so that target arithmetic can be correctly |
| 172 | /// performed on the host. Performance should nonetheless be reasonable, |
| 173 | /// particularly for its intended use. It may be useful as a base |
| 174 | /// implementation for a run-time library during development of a faster |
| 175 | /// target-specific one. |
| 176 | /// |
| 177 | /// All 5 rounding modes in the IEEE-754R draft are handled correctly for all |
| 178 | /// implemented operations. Currently implemented operations are add, subtract, |
| 179 | /// multiply, divide, fused-multiply-add, conversion-to-float, |
| 180 | /// conversion-to-integer and conversion-from-integer. New rounding modes |
| 181 | /// (e.g. away from zero) can be added with three or four lines of code. |
| 182 | /// |
| 183 | /// Four formats are built-in: IEEE single precision, double precision, |
| 184 | /// quadruple precision, and x87 80-bit extended double (when operating with |
| 185 | /// full extended precision). Adding a new format that obeys IEEE semantics |
| 186 | /// only requires adding two lines of code: a declaration and definition of the |
| 187 | /// format. |
| 188 | /// |
| 189 | /// All operations return the status of that operation as an exception bit-mask, |
| 190 | /// so multiple operations can be done consecutively with their results or-ed |
| 191 | /// together. The returned status can be useful for compiler diagnostics; e.g., |
| 192 | /// inexact, underflow and overflow can be easily diagnosed on constant folding, |
| 193 | /// and compiler optimizers can determine what exceptions would be raised by |
| 194 | /// folding operations and optimize, or perhaps not optimize, accordingly. |
| 195 | /// |
| 196 | /// At present, underflow tininess is detected after rounding; it should be |
| 197 | /// straight forward to add support for the before-rounding case too. |
| 198 | /// |
| 199 | /// The library reads hexadecimal floating point numbers as per C99, and |
| 200 | /// correctly rounds if necessary according to the specified rounding mode. |
| 201 | /// Syntax is required to have been validated by the caller. |
| 202 | /// |
| 203 | /// It also reads decimal floating point numbers and correctly rounds according |
| 204 | /// to the specified rounding mode. |
| 205 | /// |
| 206 | /// Non-zero finite numbers are represented internally as a sign bit, a 16-bit |
| 207 | /// signed exponent, and the significand as an array of integer limbs. After |
| 208 | /// normalization of a number of precision P the exponent is within the range of |
| 209 | /// the format, and if the number is not denormal the P-th bit of the |
| 210 | /// significand is set as an explicit integer bit. For denormals the most |
| 211 | /// significant bit is shifted right so that the exponent is maintained at the |
| 212 | /// format's minimum, so that the smallest denormal has just the least |
| 213 | /// significant bit of the significand set. The sign of zeros and infinities |
| 214 | /// is significant; the exponent and significand of such numbers is not stored, |
| 215 | /// but has a known implicit (deterministic) value: 0 for the significands, 0 |
| 216 | /// for zero exponent, all 1 bits for infinity exponent. For NaNs the sign and |
| 217 | /// significand are deterministic, although not really meaningful, and preserved |
| 218 | /// in non-conversion operations. The exponent is implicitly all 1 bits. |
| 219 | /// |
| 220 | /// `apfloat` does not provide any exception handling beyond default exception |
| 221 | /// handling. We represent Signaling NaNs via IEEE-754R 2008 6.2.1 should clause |
| 222 | /// by encoding Signaling NaNs with the first bit of its trailing significand as |
| 223 | /// 0. |
| 224 | /// |
| 225 | /// Future work |
| 226 | /// =========== |
| 227 | /// |
| 228 | /// Some features that may or may not be worth adding: |
| 229 | /// |
| 230 | /// Optional ability to detect underflow tininess before rounding. |
| 231 | /// |
| 232 | /// New formats: x87 in single and double precision mode (IEEE apart from |
| 233 | /// extended exponent range) (hard). |
| 234 | /// |
| 235 | /// New operations: sqrt, nexttoward. |
| 236 | /// |
| 237 | pub trait Float: |
| 238 | Copy |
| 239 | + Default |
| 240 | + FromStr<Err = ParseError> |
| 241 | + PartialOrd |
| 242 | + fmt::Display |
| 243 | + Neg<Output = Self> |
| 244 | + AddAssign |
| 245 | + SubAssign |
| 246 | + MulAssign |
| 247 | + DivAssign |
| 248 | + RemAssign |
| 249 | + Add<Output = StatusAnd<Self>> |
| 250 | + Sub<Output = StatusAnd<Self>> |
| 251 | + Mul<Output = StatusAnd<Self>> |
| 252 | + Div<Output = StatusAnd<Self>> |
| 253 | + Rem<Output = StatusAnd<Self>> |
| 254 | { |
| 255 | /// Total number of bits in the in-memory format. |
| 256 | const BITS: usize; |
| 257 | |
| 258 | /// Number of bits in the significand. This includes the integer bit. |
| 259 | const PRECISION: usize; |
| 260 | |
| 261 | /// The largest E such that 2^E is representable; this matches the |
| 262 | /// definition of IEEE 754. |
| 263 | const MAX_EXP: ExpInt; |
| 264 | |
| 265 | /// The smallest E such that 2^E is a normalized number; this |
| 266 | /// matches the definition of IEEE 754. |
| 267 | const MIN_EXP: ExpInt; |
| 268 | |
| 269 | /// Positive Zero. |
| 270 | const ZERO: Self; |
| 271 | |
| 272 | /// Positive Infinity. |
| 273 | const INFINITY: Self; |
| 274 | |
| 275 | /// NaN (Not a Number). |
| 276 | // FIXME(eddyb) provide a default when qnan becomes const fn. |
| 277 | const NAN: Self; |
| 278 | |
| 279 | /// Factory for QNaN values. |
| 280 | // FIXME(eddyb) should be const fn. |
| 281 | fn qnan(payload: Option<u128>) -> Self; |
| 282 | |
| 283 | /// Factory for SNaN values. |
| 284 | // FIXME(eddyb) should be const fn. |
| 285 | fn snan(payload: Option<u128>) -> Self; |
| 286 | |
| 287 | /// Largest finite number. |
| 288 | // FIXME(eddyb) should be const (but FloatPair::largest is nontrivial). |
| 289 | fn largest() -> Self; |
| 290 | |
| 291 | /// Smallest (by magnitude) finite number. |
| 292 | /// Might be denormalized, which implies a relative loss of precision. |
| 293 | const SMALLEST: Self; |
| 294 | |
| 295 | /// Smallest (by magnitude) normalized finite number. |
| 296 | // FIXME(eddyb) should be const (but FloatPair::smallest_normalized is nontrivial). |
| 297 | fn smallest_normalized() -> Self; |
| 298 | |
| 299 | // Arithmetic |
| 300 | |
| 301 | fn add_r(self, rhs: Self, round: Round) -> StatusAnd<Self>; |
| 302 | fn sub_r(self, rhs: Self, round: Round) -> StatusAnd<Self> { |
| 303 | self.add_r(-rhs, round) |
| 304 | } |
| 305 | fn mul_r(self, rhs: Self, round: Round) -> StatusAnd<Self>; |
| 306 | fn mul_add_r(self, multiplicand: Self, addend: Self, round: Round) -> StatusAnd<Self>; |
| 307 | fn mul_add(self, multiplicand: Self, addend: Self) -> StatusAnd<Self> { |
| 308 | self.mul_add_r(multiplicand, addend, Round::NearestTiesToEven) |
| 309 | } |
| 310 | fn div_r(self, rhs: Self, round: Round) -> StatusAnd<Self>; |
| 311 | /// IEEE remainder. |
| 312 | fn ieee_rem(self, rhs: Self) -> StatusAnd<Self>; |
| 313 | /// C fmod, or llvm frem. |
| 314 | fn c_fmod(self, rhs: Self) -> StatusAnd<Self>; |
| 315 | fn round_to_integral(self, round: Round) -> StatusAnd<Self>; |
| 316 | |
| 317 | /// IEEE-754R 2008 5.3.1: nextUp. |
| 318 | fn next_up(self) -> StatusAnd<Self>; |
| 319 | |
| 320 | /// IEEE-754R 2008 5.3.1: nextDown. |
| 321 | /// |
| 322 | /// *NOTE* since nextDown(x) = -nextUp(-x), we only implement nextUp with |
| 323 | /// appropriate sign switching before/after the computation. |
| 324 | fn next_down(self) -> StatusAnd<Self> { |
| 325 | (-self).next_up().map(|r| -r) |
| 326 | } |
| 327 | |
| 328 | fn abs(self) -> Self { |
| 329 | if self.is_negative() { |
| 330 | -self |
| 331 | } else { |
| 332 | self |
| 333 | } |
| 334 | } |
| 335 | fn copy_sign(self, rhs: Self) -> Self { |
| 336 | if self.is_negative() != rhs.is_negative() { |
| 337 | -self |
| 338 | } else { |
| 339 | self |
| 340 | } |
| 341 | } |
| 342 | |
| 343 | // Conversions |
| 344 | fn from_bits(input: u128) -> Self; |
| 345 | fn from_i128_r(input: i128, round: Round) -> StatusAnd<Self> { |
| 346 | if input < 0 { |
| 347 | Self::from_u128_r(input.wrapping_neg() as u128, -round).map(|r| -r) |
| 348 | } else { |
| 349 | Self::from_u128_r(input as u128, round) |
| 350 | } |
| 351 | } |
| 352 | fn from_i128(input: i128) -> StatusAnd<Self> { |
| 353 | Self::from_i128_r(input, Round::NearestTiesToEven) |
| 354 | } |
| 355 | fn from_u128_r(input: u128, round: Round) -> StatusAnd<Self>; |
| 356 | fn from_u128(input: u128) -> StatusAnd<Self> { |
| 357 | Self::from_u128_r(input, Round::NearestTiesToEven) |
| 358 | } |
| 359 | fn from_str_r(s: &str, round: Round) -> Result<StatusAnd<Self>, ParseError>; |
| 360 | fn to_bits(self) -> u128; |
| 361 | |
| 362 | /// Convert a floating point number to an integer according to the |
| 363 | /// rounding mode. In case of an invalid operation exception, |
| 364 | /// deterministic values are returned, namely zero for NaNs and the |
| 365 | /// minimal or maximal value respectively for underflow or overflow. |
| 366 | /// If the rounded value is in range but the floating point number is |
| 367 | /// not the exact integer, the C standard doesn't require an inexact |
| 368 | /// exception to be raised. IEEE-854 does require it so we do that. |
| 369 | /// |
| 370 | /// Note that for conversions to integer type the C standard requires |
| 371 | /// round-to-zero to always be used. |
| 372 | /// |
| 373 | /// The *is_exact output tells whether the result is exact, in the sense |
| 374 | /// that converting it back to the original floating point type produces |
| 375 | /// the original value. This is almost equivalent to result==Status::OK, |
| 376 | /// except for negative zeroes. |
| 377 | fn to_i128_r(self, width: usize, round: Round, is_exact: &mut bool) -> StatusAnd<i128> { |
| 378 | let status; |
| 379 | if self.is_negative() { |
| 380 | if self.is_zero() { |
| 381 | // Negative zero can't be represented as an int. |
| 382 | *is_exact = false; |
| 383 | } |
| 384 | let r = unpack!(status=, (-self).to_u128_r(width, -round, is_exact)); |
| 385 | |
| 386 | // Check for values that don't fit in the signed integer. |
| 387 | if r > (1 << (width - 1)) { |
| 388 | // Return the most negative integer for the given width. |
| 389 | *is_exact = false; |
| 390 | Status::INVALID_OP.and(-1 << (width - 1)) |
| 391 | } else { |
| 392 | status.and(r.wrapping_neg() as i128) |
| 393 | } |
| 394 | } else { |
| 395 | // Positive case is simpler, can pretend it's a smaller unsigned |
| 396 | // integer, and `to_u128` will take care of all the edge cases. |
| 397 | self.to_u128_r(width - 1, round, is_exact).map(|r| r as i128) |
| 398 | } |
| 399 | } |
| 400 | fn to_i128(self, width: usize) -> StatusAnd<i128> { |
| 401 | self.to_i128_r(width, Round::TowardZero, &mut true) |
| 402 | } |
| 403 | fn to_u128_r(self, width: usize, round: Round, is_exact: &mut bool) -> StatusAnd<u128>; |
| 404 | fn to_u128(self, width: usize) -> StatusAnd<u128> { |
| 405 | self.to_u128_r(width, Round::TowardZero, &mut true) |
| 406 | } |
| 407 | |
| 408 | fn cmp_abs_normal(self, rhs: Self) -> Ordering; |
| 409 | |
| 410 | /// Bitwise comparison for equality (QNaNs compare equal, 0!=-0). |
| 411 | fn bitwise_eq(self, rhs: Self) -> bool; |
| 412 | |
| 413 | // IEEE-754R 5.7.2 General operations. |
| 414 | |
| 415 | /// Implements IEEE minNum semantics. Returns the smaller of the 2 arguments if |
| 416 | /// both are not NaN. If either argument is a NaN, returns the other argument. |
| 417 | fn min(self, other: Self) -> Self { |
| 418 | if self.is_nan() { |
| 419 | other |
| 420 | } else if other.is_nan() { |
| 421 | self |
| 422 | } else if other < self { |
| 423 | other |
| 424 | } else { |
| 425 | self |
| 426 | } |
| 427 | } |
| 428 | |
| 429 | /// Implements IEEE maxNum semantics. Returns the larger of the 2 arguments if |
| 430 | /// both are not NaN. If either argument is a NaN, returns the other argument. |
| 431 | fn max(self, other: Self) -> Self { |
| 432 | if self.is_nan() { |
| 433 | other |
| 434 | } else if other.is_nan() { |
| 435 | self |
| 436 | } else if self < other { |
| 437 | other |
| 438 | } else { |
| 439 | self |
| 440 | } |
| 441 | } |
| 442 | |
| 443 | /// Implements IEEE 754-2018 minimum semantics. Returns the smaller of 2 |
| 444 | /// arguments, propagating NaNs and treating -0 as less than +0. |
| 445 | fn minimum(self, other: Self) -> Self { |
| 446 | if self.is_nan() { |
| 447 | self |
| 448 | } else if other.is_nan() { |
| 449 | other |
| 450 | } else if self.is_zero() && other.is_zero() && self.is_negative() != other.is_negative() { |
| 451 | if self.is_negative() { |
| 452 | self |
| 453 | } else { |
| 454 | other |
| 455 | } |
| 456 | } else if other < self { |
| 457 | other |
| 458 | } else { |
| 459 | self |
| 460 | } |
| 461 | } |
| 462 | |
| 463 | /// Implements IEEE 754-2018 maximum semantics. Returns the larger of 2 |
| 464 | /// arguments, propagating NaNs and treating -0 as less than +0. |
| 465 | fn maximum(self, other: Self) -> Self { |
| 466 | if self.is_nan() { |
| 467 | self |
| 468 | } else if other.is_nan() { |
| 469 | other |
| 470 | } else if self.is_zero() && other.is_zero() && self.is_negative() != other.is_negative() { |
| 471 | if self.is_negative() { |
| 472 | other |
| 473 | } else { |
| 474 | self |
| 475 | } |
| 476 | } else if self < other { |
| 477 | other |
| 478 | } else { |
| 479 | self |
| 480 | } |
| 481 | } |
| 482 | |
| 483 | /// IEEE-754R isSignMinus: Returns true if and only if the current value is |
| 484 | /// negative. |
| 485 | /// |
| 486 | /// This applies to zeros and NaNs as well. |
| 487 | fn is_negative(self) -> bool; |
| 488 | |
| 489 | /// IEEE-754R isNormal: Returns true if and only if the current value is normal. |
| 490 | /// |
| 491 | /// This implies that the current value of the float is not zero, subnormal, |
| 492 | /// infinite, or NaN following the definition of normality from IEEE-754R. |
| 493 | fn is_normal(self) -> bool { |
| 494 | !self.is_denormal() && self.is_finite_non_zero() |
| 495 | } |
| 496 | |
| 497 | /// Returns true if and only if the current value is zero, subnormal, or |
| 498 | /// normal. |
| 499 | /// |
| 500 | /// This means that the value is not infinite or NaN. |
| 501 | fn is_finite(self) -> bool { |
| 502 | !self.is_nan() && !self.is_infinite() |
| 503 | } |
| 504 | |
| 505 | /// Returns true if and only if the float is plus or minus zero. |
| 506 | fn is_zero(self) -> bool { |
| 507 | self.category() == Category::Zero |
| 508 | } |
| 509 | |
| 510 | /// IEEE-754R isSubnormal(): Returns true if and only if the float is a |
| 511 | /// denormal. |
| 512 | fn is_denormal(self) -> bool; |
| 513 | |
| 514 | /// IEEE-754R isInfinite(): Returns true if and only if the float is infinity. |
| 515 | fn is_infinite(self) -> bool { |
| 516 | self.category() == Category::Infinity |
| 517 | } |
| 518 | |
| 519 | /// Returns true if and only if the float is a quiet or signaling NaN. |
| 520 | fn is_nan(self) -> bool { |
| 521 | self.category() == Category::NaN |
| 522 | } |
| 523 | |
| 524 | /// Returns true if and only if the float is a signaling NaN. |
| 525 | fn is_signaling(self) -> bool; |
| 526 | |
| 527 | // Simple Queries |
| 528 | |
| 529 | fn category(self) -> Category; |
| 530 | fn is_non_zero(self) -> bool { |
| 531 | !self.is_zero() |
| 532 | } |
| 533 | fn is_finite_non_zero(self) -> bool { |
| 534 | self.is_finite() && !self.is_zero() |
| 535 | } |
| 536 | fn is_pos_zero(self) -> bool { |
| 537 | self.is_zero() && !self.is_negative() |
| 538 | } |
| 539 | fn is_neg_zero(self) -> bool { |
| 540 | self.is_zero() && self.is_negative() |
| 541 | } |
| 542 | fn is_pos_infinity(self) -> bool { |
| 543 | self.is_infinite() && !self.is_negative() |
| 544 | } |
| 545 | fn is_neg_infinity(self) -> bool { |
| 546 | self.is_infinite() && self.is_negative() |
| 547 | } |
| 548 | |
| 549 | /// Returns true if and only if the number has the smallest possible non-zero |
| 550 | /// magnitude in the current semantics. |
| 551 | fn is_smallest(self) -> bool { |
| 552 | Self::SMALLEST.copy_sign(self).bitwise_eq(self) |
| 553 | } |
| 554 | |
| 555 | /// Returns true if this is the smallest (by magnitude) normalized finite |
| 556 | /// number in the given semantics. |
| 557 | fn is_smallest_normalized(self) -> bool { |
| 558 | Self::smallest_normalized().copy_sign(self).bitwise_eq(self) |
| 559 | } |
| 560 | |
| 561 | /// Returns true if and only if the number has the largest possible finite |
| 562 | /// magnitude in the current semantics. |
| 563 | fn is_largest(self) -> bool { |
| 564 | Self::largest().copy_sign(self).bitwise_eq(self) |
| 565 | } |
| 566 | |
| 567 | /// Returns true if and only if the number is an exact integer. |
| 568 | fn is_integer(self) -> bool { |
| 569 | // This could be made more efficient; I'm going for obviously correct. |
| 570 | if !self.is_finite() { |
| 571 | return false; |
| 572 | } |
| 573 | self.round_to_integral(Round::TowardZero).value.bitwise_eq(self) |
| 574 | } |
| 575 | |
| 576 | /// If this value has an exact multiplicative inverse, return it. |
| 577 | fn get_exact_inverse(self) -> Option<Self>; |
| 578 | |
| 579 | /// Returns the exponent of the internal representation of the Float. |
| 580 | /// |
| 581 | /// Because the radix of Float is 2, this is equivalent to floor(log2(x)). |
| 582 | /// For special Float values, this returns special error codes: |
| 583 | /// |
| 584 | /// NaN -> \c IEK_NAN |
| 585 | /// 0 -> \c IEK_ZERO |
| 586 | /// Inf -> \c IEK_INF |
| 587 | /// |
| 588 | fn ilogb(self) -> ExpInt; |
| 589 | |
| 590 | /// Returns: self * 2^exp for integral exponents. |
| 591 | fn scalbn_r(self, exp: ExpInt, round: Round) -> Self; |
| 592 | fn scalbn(self, exp: ExpInt) -> Self { |
| 593 | self.scalbn_r(exp, Round::NearestTiesToEven) |
| 594 | } |
| 595 | |
| 596 | /// Equivalent of C standard library function. |
| 597 | /// |
| 598 | /// While the C standard says exp is an unspecified value for infinity and nan, |
| 599 | /// this returns INT_MAX for infinities, and INT_MIN for NaNs (see `ilogb`). |
| 600 | fn frexp_r(self, exp: &mut ExpInt, round: Round) -> Self; |
| 601 | fn frexp(self, exp: &mut ExpInt) -> Self { |
| 602 | self.frexp_r(exp, Round::NearestTiesToEven) |
| 603 | } |
| 604 | } |
| 605 | |
| 606 | /// Convert between floating point types. |
| 607 | pub trait FloatConvert<T: Float>: Float { |
| 608 | /// Convert a value of one floating point type to another. |
| 609 | /// The return value corresponds to the IEEE754 exceptions. *loses_info |
| 610 | /// records whether the transformation lost information, i.e. whether |
| 611 | /// converting the result back to the original type will produce the |
| 612 | /// original value (this is almost the same as return value==Status::OK, |
| 613 | /// but there are edge cases where this is not so). |
| 614 | fn convert_r(self, round: Round, loses_info: &mut bool) -> StatusAnd<T>; |
| 615 | |
| 616 | /// Convert with default [`NearestTiesToEven`](Round::NearestTiesToEven) rounding. |
| 617 | fn convert(self, loses_info: &mut bool) -> StatusAnd<T> { |
| 618 | self.convert_r(Round::NearestTiesToEven, loses_info) |
| 619 | } |
| 620 | } |
| 621 | |
| 622 | macro_rules! float_common_impls { |
| 623 | ($ty:ident<$t:tt>) => { |
| 624 | impl<$t> Default for $ty<$t> |
| 625 | where |
| 626 | Self: Float, |
| 627 | { |
| 628 | #[inline] |
| 629 | fn default() -> Self { |
| 630 | Self::ZERO |
| 631 | } |
| 632 | } |
| 633 | |
| 634 | impl<$t> ::core::str::FromStr for $ty<$t> |
| 635 | where |
| 636 | Self: Float, |
| 637 | { |
| 638 | type Err = ParseError; |
| 639 | #[inline] |
| 640 | fn from_str(s: &str) -> Result<Self, ParseError> { |
| 641 | Self::from_str_r(s, Round::NearestTiesToEven).map(|x| x.value) |
| 642 | } |
| 643 | } |
| 644 | |
| 645 | // Rounding ties to the nearest even, by default. |
| 646 | |
| 647 | impl<$t> ::core::ops::Add for $ty<$t> |
| 648 | where |
| 649 | Self: Float, |
| 650 | { |
| 651 | type Output = StatusAnd<Self>; |
| 652 | #[inline] |
| 653 | fn add(self, rhs: Self) -> StatusAnd<Self> { |
| 654 | self.add_r(rhs, Round::NearestTiesToEven) |
| 655 | } |
| 656 | } |
| 657 | |
| 658 | impl<$t> ::core::ops::Sub for $ty<$t> |
| 659 | where |
| 660 | Self: Float, |
| 661 | { |
| 662 | type Output = StatusAnd<Self>; |
| 663 | #[inline] |
| 664 | fn sub(self, rhs: Self) -> StatusAnd<Self> { |
| 665 | self.sub_r(rhs, Round::NearestTiesToEven) |
| 666 | } |
| 667 | } |
| 668 | |
| 669 | impl<$t> ::core::ops::Mul for $ty<$t> |
| 670 | where |
| 671 | Self: Float, |
| 672 | { |
| 673 | type Output = StatusAnd<Self>; |
| 674 | #[inline] |
| 675 | fn mul(self, rhs: Self) -> StatusAnd<Self> { |
| 676 | self.mul_r(rhs, Round::NearestTiesToEven) |
| 677 | } |
| 678 | } |
| 679 | |
| 680 | impl<$t> ::core::ops::Div for $ty<$t> |
| 681 | where |
| 682 | Self: Float, |
| 683 | { |
| 684 | type Output = StatusAnd<Self>; |
| 685 | #[inline] |
| 686 | fn div(self, rhs: Self) -> StatusAnd<Self> { |
| 687 | self.div_r(rhs, Round::NearestTiesToEven) |
| 688 | } |
| 689 | } |
| 690 | |
| 691 | impl<$t> ::core::ops::Rem for $ty<$t> |
| 692 | where |
| 693 | Self: Float, |
| 694 | { |
| 695 | type Output = StatusAnd<Self>; |
| 696 | #[inline] |
| 697 | fn rem(self, rhs: Self) -> StatusAnd<Self> { |
| 698 | self.c_fmod(rhs) |
| 699 | } |
| 700 | } |
| 701 | |
| 702 | impl<$t> ::core::ops::AddAssign for $ty<$t> |
| 703 | where |
| 704 | Self: Float, |
| 705 | { |
| 706 | #[inline] |
| 707 | fn add_assign(&mut self, rhs: Self) { |
| 708 | *self = (*self + rhs).value; |
| 709 | } |
| 710 | } |
| 711 | |
| 712 | impl<$t> ::core::ops::SubAssign for $ty<$t> |
| 713 | where |
| 714 | Self: Float, |
| 715 | { |
| 716 | #[inline] |
| 717 | fn sub_assign(&mut self, rhs: Self) { |
| 718 | *self = (*self - rhs).value; |
| 719 | } |
| 720 | } |
| 721 | |
| 722 | impl<$t> ::core::ops::MulAssign for $ty<$t> |
| 723 | where |
| 724 | Self: Float, |
| 725 | { |
| 726 | #[inline] |
| 727 | fn mul_assign(&mut self, rhs: Self) { |
| 728 | *self = (*self * rhs).value; |
| 729 | } |
| 730 | } |
| 731 | |
| 732 | impl<$t> ::core::ops::DivAssign for $ty<$t> |
| 733 | where |
| 734 | Self: Float, |
| 735 | { |
| 736 | #[inline] |
| 737 | fn div_assign(&mut self, rhs: Self) { |
| 738 | *self = (*self / rhs).value; |
| 739 | } |
| 740 | } |
| 741 | |
| 742 | impl<$t> ::core::ops::RemAssign for $ty<$t> |
| 743 | where |
| 744 | Self: Float, |
| 745 | { |
| 746 | #[inline] |
| 747 | fn rem_assign(&mut self, rhs: Self) { |
| 748 | *self = (*self % rhs).value; |
| 749 | } |
| 750 | } |
| 751 | }; |
| 752 | } |
| 753 | |
| 754 | pub mod ieee; |
| 755 | pub mod ppc; |
| 756 | |