minimal-lexical 0.1.0

Fast float parsing conversion routines.
Documentation 
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//! Bit-shift helpers.

use crate::lib::mem;
use super::float::ExtendedFloat;

// Shift extended-precision float right `shift` bytes.
#[inline]
pub(crate) fn shr(fp: &mut ExtendedFloat, shift: i32)
{
    let bits: u64 = mem::size_of::<u64>() as u64 * 8;
    debug_assert!((shift as u64) < bits, "shr() overflow in shift right.");

    fp.mant >>= shift;
    fp.exp += shift;
}

// Shift extended-precision float right `shift` bytes.
//
// Accepts when the shift is the same as the type size, and
// sets the value to 0.
#[inline]
pub(crate) fn overflowing_shr(fp: &mut ExtendedFloat, shift: i32)
{
    let bits: u64 = mem::size_of::<u64>() as u64 * 8;
    debug_assert!((shift as u64) <= bits, "overflowing_shr() overflow in shift right.");

    fp.mant = match shift as u64 == bits {
        true  => 0,
        false => fp.mant >> shift,
    };
    fp.exp += shift;
}

// Shift extended-precision float left `shift` bytes.
#[inline]
pub(crate) fn shl(fp: &mut ExtendedFloat, shift: i32)
{
    let bits: u64 = mem::size_of::<u64>() as u64 * 8;
    debug_assert!((shift as u64) < bits, "shl() overflow in shift left.");

    fp.mant <<= shift;
    fp.exp -= shift;
}