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fix 2's-completement encoding for non full with signed ints

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This commit is contained in:
Robin Appelman 2019-08-28 02:44:35 +02:00
commit 2fd2b49810
3 changed files with 22 additions and 44 deletions
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16
src/buffer.rs
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@ -3,7 +3,7 @@ use std::fmt;
use std::fmt::Debug;
use std::marker::PhantomData;
use std::mem::size_of;
use std::ops::BitOrAssign;
use std::ops::{BitOrAssign, BitXor};
use std::rc::Rc;
use num_traits::{Float, PrimInt};
@ -190,7 +190,7 @@ where
#[inline]
pub fn read_int<T>(&self, position: usize, count: usize) -> Result<T>
where
T: PrimInt + BitOrAssign + IsSigned + UncheckedPrimitiveInt,
T: PrimInt + BitOrAssign + IsSigned + UncheckedPrimitiveInt + BitXor,
{
let type_bit_size = size_of::<T>() * 8;
@ -227,7 +227,7 @@ where
self.read_no_fit_usize(position, count)
};
if count == type_bit_size && fit_usize {
if count == type_bit_size {
Ok(value)
} else {
Ok(self.make_signed(value, count))
@ -278,13 +278,15 @@ where
fn make_signed<T>(&self, value: T, count: usize) -> T
where
T: PrimInt + BitOrAssign + IsSigned + UncheckedPrimitiveInt,
T: PrimInt + BitOrAssign + IsSigned + UncheckedPrimitiveInt + BitXor,
{
if T::is_signed() {
let sign_bit = value >> (count - 1) & T::one();
let absolute_value = value & !(T::max_value() << (count - 1));
let sign = T::one() - sign_bit - sign_bit;
absolute_value * sign
if sign_bit == T::one() {
value | (T::zero() - T::one()) ^ ((T::one() << count) - T::one())
} else {
value
}
} else {
value
}