opthash 0.1.2

Rust implementations of Elastic Hashing and Funnel Hashing
Documentation 
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use super::config::{DEFAULT_RESERVE_FRACTION, MAX_RESERVE_FRACTION, MIN_RESERVE_FRACTION};
use super::layout::GROUP_SIZE;

#[allow(clippy::cast_precision_loss)]
#[inline]
pub(crate) fn usize_to_f64(value: usize) -> f64 {
    value as f64
}

#[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
#[inline]
pub(crate) fn floor_to_usize(value: f64) -> usize {
    value.floor() as usize
}

#[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
#[inline]
pub(crate) fn ceil_to_usize(value: f64) -> usize {
    value.ceil() as usize
}

#[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
#[inline]
pub(crate) fn round_to_usize(value: f64) -> usize {
    value.round() as usize
}

#[inline]
pub(crate) fn max_insertions(capacity: usize, reserve_fraction: f64) -> usize {
    capacity.saturating_sub(floor_to_usize(reserve_fraction * usize_to_f64(capacity)))
}

pub(crate) fn sanitize_reserve_fraction(reserve_fraction: f64) -> f64 {
    if reserve_fraction.is_finite() {
        reserve_fraction.clamp(MIN_RESERVE_FRACTION, MAX_RESERVE_FRACTION)
    } else {
        DEFAULT_RESERVE_FRACTION
    }
}

pub(crate) fn ceil_three_quarters(value: usize) -> usize {
    (value.saturating_mul(3).saturating_add(3)) / 4
}

pub(crate) fn floor_half_reserve_slots(reserve_fraction: f64, value: usize) -> usize {
    floor_to_usize((reserve_fraction * usize_to_f64(value)) / 2.0)
}

pub(crate) fn greatest_common_divisor(mut a: usize, mut b: usize) -> usize {
    while b != 0 {
        let remainder = a % b;
        a = b;
        b = remainder;
    }
    a
}

#[inline]
pub(crate) fn advance_wrapping_index(current: usize, step: usize, len: usize) -> usize {
    let next = current + step;
    if next >= len { next - len } else { next }
}

#[inline]
pub(crate) fn round_up_to_group(value: usize) -> usize {
    if value == 0 {
        0
    } else {
        value.div_ceil(GROUP_SIZE) * GROUP_SIZE
    }
}