Struct DecimalSeq

impl DecimalSeq

const MAX_DIGITS: usize = 768;

The maximum number of digits required to unambiguously round up to a 64-bit float.

For an IEEE 754 binary64 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))

const MAX_DIGITS_WITHOUT_OVERFLOW: usize = 19;

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

const DECIMAL_POINT_RANGE: i32 = 2047;

fn try_add_digit(&mut self, digit: u8)

Append a digit to the buffer if it fits.

fn trim(&mut self)

Trim trailing zeros from the buffer.

fn round(&self) -> u64

fn left_shift(&mut self, shift: usize)

Computes decimal * 2^shift.

fn right_shift(&mut self, shift: usize)

Computes decimal * 2^-shift.