Struct core::num::dec2flt::decimal::Decimal

pub struct Decimal {
    pub num_digits: usize,
    pub decimal_point: i32,
    pub truncated: bool,
    pub digits: [u8; 768],
}

🔬This is a nightly-only experimental API. (dec2flt)

Fields

num_digits: usize

🔬This is a nightly-only experimental API. (dec2flt)

The number of significant digits in the decimal.

decimal_point: i32

🔬This is a nightly-only experimental API. (dec2flt)

The offset of the decimal point in the significant digits.

truncated: bool

🔬This is a nightly-only experimental API. (dec2flt)

If the number of significant digits stored in the decimal is truncated.

digits: [u8; 768]

🔬This is a nightly-only experimental API. (dec2flt)

Buffer of the raw digits, in the range [0, 9].

Implementations

impl Decimal

pub const MAX_DIGITS: usize = 768usize

🔬This is a nightly-only experimental API. (dec2flt)

The maximum number of digits required to unambiguously round a float.

For a double-precision IEEE 754 float, this required 767 digits, so we store the max digits + 1.

We can exactly represent a float in radix b from radix 2 if b is divisible by 2. This function calculates the exact number of digits required to exactly represent that float.

According to the “Handbook of Floating Point Arithmetic”, for IEEE754, with emin being the min exponent, p2 being the precision, and b being the radix, the number of digits follows as:

−emin + p2 + ⌊(emin + 1) log(2, b) − log(1 − 2^(−p2), b)⌋

For f32, this follows as: emin = -126 p2 = 24

For f64, this follows as: emin = -1022 p2 = 53

In Python: -emin + p2 + math.floor((emin+ 1)*math.log(2, b)-math.log(1-2**(-p2), b))

pub const MAX_DIGITS_WITHOUT_OVERFLOW: usize = 19usize

🔬This is a nightly-only experimental API. (dec2flt)

The max digits that can be exactly represented in a 64-bit integer.

pub const DECIMAL_POINT_RANGE: i32 = 2_047i32

🔬This is a nightly-only experimental API. (dec2flt)

pub fn try_add_digit(&mut self, digit: u8)

🔬This is a nightly-only experimental API. (dec2flt)

Append a digit to the buffer.

pub fn trim(&mut self)

🔬This is a nightly-only experimental API. (dec2flt)

Trim trailing zeros from the buffer.

pub fn round(&self) -> u64

🔬This is a nightly-only experimental API. (dec2flt)

pub fn left_shift(&mut self, shift: usize)

🔬This is a nightly-only experimental API. (dec2flt)

Computes decimal * 2^shift.

pub fn right_shift(&mut self, shift: usize)

🔬This is a nightly-only experimental API. (dec2flt)

Computes decimal * 2^-shift.

Trait Implementations

impl Clone for Decimal

fn clone(&self) -> Decimal

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for Decimal

fn default() -> Self

Returns the “default value” for a type.