mozilla-central/third_party/rust/dtoa/src/lib.rs (file symbol)

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//! [![github]](https://github.com/dtolnay/dtoa) [![crates-io]](https://crates.io/crates/dtoa) [![docs-rs]](https://docs.rs/dtoa)
//!
//!
//! <br>
//!
//! This crate provides fast functions for printing floating-point primitives to
//! an [`io::Write`]. The implementation is a straightforward Rust port of [Milo
//! Yip]'s C++ implementation [dtoa.h]. The original C++ code of each function
//! is included in comments.
//!
//! See also [`itoa`] for printing integer primitives.
//!
//! [Milo Yip]: https://github.com/miloyip
//!
//! <br>
//!
//! ## Performance (lower is better)
//!
//!
//! <br>
//!
//! # Examples
//!
//! ```edition2018
//! use std::io;
//!
//! fn main() -> io::Result<()> {
//! // Write to a vector or other io::Write.
//! let mut buf = Vec::new();
//! dtoa::write(&mut buf, 2.71828f64)?;
//! println!("{:?}", buf);
//!
//! // Write to a stack buffer.
//! let mut bytes = [b'\0'; 20];
//! let n = dtoa::write(&mut bytes[..], 2.71828f64)?;
//! println!("{:?}", &bytes[..n]);
//!
//! Ok(())
//! }
//! ```
#![doc(html_root_url = "https://docs.rs/dtoa/0.4.8")]
#![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
#![cfg_attr(
feature = "cargo-clippy",
allow(
cast_lossless,
cast_possible_truncation,
if_not_else,
missing_errors_doc,
range_plus_one,
shadow_unrelated,
transmute_float_to_int,
unreadable_literal,
unseparated_literal_suffix
)
)]
#[macro_use] mod diyfp;
#[macro_use] mod dtoa;
use std::{io, mem, ops, ptr, slice};
/// Write float to an `io::Write`.
#[inline]
pub fn write<W: io::Write, V: Floating>(wr: W, value: V) -> io::Result<usize> {
value.write(wr)
}
/// An floating point number that can be formatted by `dtoa::write`.
pub trait Floating {
fn write<W: io::Write>(self, wr: W) -> io::Result<usize>;
}
impl Floating for f32 {
fn write<W: io::Write>(self, wr: W) -> io::Result<usize> {
dtoa! {
floating_type: f32,
significand_type: u32,
exponent_type: i32,
diy_significand_size: 32,
significand_size: 23,
exponent_bias: 0x7F,
mask_type: u32,
exponent_mask: 0x7F800000,
significand_mask: 0x007FFFFF,
hidden_bit: 0x00800000,
cached_powers_f: CACHED_POWERS_F_32,
cached_powers_e: CACHED_POWERS_E_32,
min_power: (-36),
};
unsafe { dtoa(wr, self) }
}
}
impl Floating for f64 {
fn write<W: io::Write>(self, wr: W) -> io::Result<usize> {
dtoa! {
floating_type: f64,
significand_type: u64,
exponent_type: isize,
diy_significand_size: 64,
significand_size: 52,
exponent_bias: 0x3FF,
mask_type: u64,
exponent_mask: 0x7FF0000000000000,
significand_mask: 0x000FFFFFFFFFFFFF,
hidden_bit: 0x0010000000000000,
cached_powers_f: CACHED_POWERS_F_64,
cached_powers_e: CACHED_POWERS_E_64,
min_power: (-348),
};
unsafe { dtoa(wr, self) }
}
}
////////////////////////////////////////////////////////////////////////////////
const MAX_DECIMAL_PLACES: isize = 324;
static DEC_DIGITS_LUT: [u8; 200] = *b"\
0001020304050607080910111213141516171819\
2021222324252627282930313233343536373839\
4041424344454647484950515253545556575859\
6061626364656667686970717273747576777879\
8081828384858687888990919293949596979899";
// 10^-36, 10^-28, ..., 10^52
static CACHED_POWERS_F_32: [u32; 12] = [
0xaa242499, 0xfd87b5f3, 0xbce50865, 0x8cbccc09,
0xd1b71759, 0x9c400000, 0xe8d4a510, 0xad78ebc6,
0x813f3979, 0xc097ce7c, 0x8f7e32ce, 0xd5d238a5,
];
static CACHED_POWERS_E_32: [i16; 12] = [
-151, -125, -98, -71, -45, -18, 8, 35, 62, 88, 115, 141,
];
// 10^-348, 10^-340, ..., 10^340
static CACHED_POWERS_F_64: [u64; 87] = [
0xfa8fd5a0081c0288, 0xbaaee17fa23ebf76,
0x8b16fb203055ac76, 0xcf42894a5dce35ea,
0x9a6bb0aa55653b2d, 0xe61acf033d1a45df,
0xab70fe17c79ac6ca, 0xff77b1fcbebcdc4f,
0xbe5691ef416bd60c, 0x8dd01fad907ffc3c,
0xd3515c2831559a83, 0x9d71ac8fada6c9b5,
0xea9c227723ee8bcb, 0xaecc49914078536d,
0x823c12795db6ce57, 0xc21094364dfb5637,
0x9096ea6f3848984f, 0xd77485cb25823ac7,
0xa086cfcd97bf97f4, 0xef340a98172aace5,
0xb23867fb2a35b28e, 0x84c8d4dfd2c63f3b,
0xc5dd44271ad3cdba, 0x936b9fcebb25c996,
0xdbac6c247d62a584, 0xa3ab66580d5fdaf6,
0xf3e2f893dec3f126, 0xb5b5ada8aaff80b8,
0x87625f056c7c4a8b, 0xc9bcff6034c13053,
0x964e858c91ba2655, 0xdff9772470297ebd,
0xa6dfbd9fb8e5b88f, 0xf8a95fcf88747d94,
0xb94470938fa89bcf, 0x8a08f0f8bf0f156b,
0xcdb02555653131b6, 0x993fe2c6d07b7fac,
0xe45c10c42a2b3b06, 0xaa242499697392d3,
0xfd87b5f28300ca0e, 0xbce5086492111aeb,
0x8cbccc096f5088cc, 0xd1b71758e219652c,
0x9c40000000000000, 0xe8d4a51000000000,
0xad78ebc5ac620000, 0x813f3978f8940984,
0xc097ce7bc90715b3, 0x8f7e32ce7bea5c70,
0xd5d238a4abe98068, 0x9f4f2726179a2245,
0xed63a231d4c4fb27, 0xb0de65388cc8ada8,
0x83c7088e1aab65db, 0xc45d1df942711d9a,
0x924d692ca61be758, 0xda01ee641a708dea,
0xa26da3999aef774a, 0xf209787bb47d6b85,
0xb454e4a179dd1877, 0x865b86925b9bc5c2,
0xc83553c5c8965d3d, 0x952ab45cfa97a0b3,
0xde469fbd99a05fe3, 0xa59bc234db398c25,
0xf6c69a72a3989f5c, 0xb7dcbf5354e9bece,
0x88fcf317f22241e2, 0xcc20ce9bd35c78a5,
0x98165af37b2153df, 0xe2a0b5dc971f303a,
0xa8d9d1535ce3b396, 0xfb9b7cd9a4a7443c,
0xbb764c4ca7a44410, 0x8bab8eefb6409c1a,
0xd01fef10a657842c, 0x9b10a4e5e9913129,
0xe7109bfba19c0c9d, 0xac2820d9623bf429,
0x80444b5e7aa7cf85, 0xbf21e44003acdd2d,
0x8e679c2f5e44ff8f, 0xd433179d9c8cb841,
0x9e19db92b4e31ba9, 0xeb96bf6ebadf77d9,
0xaf87023b9bf0ee6b,
];
static CACHED_POWERS_E_64: [i16; 87] = [
-1220, -1193, -1166, -1140, -1113, -1087, -1060, -1034, -1007, -980,
-954, -927, -901, -874, -847, -821, -794, -768, -741, -715,
-688, -661, -635, -608, -582, -555, -529, -502, -475, -449,
-422, -396, -369, -343, -316, -289, -263, -236, -210, -183,
-157, -130, -103, -77, -50, -24, 3, 30, 56, 83,
109, 136, 162, 189, 216, 242, 269, 295, 322, 348,
375, 402, 428, 455, 481, 508, 534, 561, 588, 614,
641, 667, 694, 720, 747, 774, 800, 827, 853, 880,
907, 933, 960, 986, 1013, 1039, 1066,
];