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fix writing larger int types in big endian

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This commit is contained in:
Robin Appelman 2024-04-04 19:39:30 +02:00
commit b46bc881f0
3 changed files with 69 additions and 23 deletions
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72
src/num_traits.rs
View file

@ -277,7 +277,7 @@ impl_is_signed!(isize, true);
pub trait SplitFitUsize {
type Iter: Iterator<Item = (usize, u8)> + ExactSizeIterator + DoubleEndedIterator;
fn split_fit_usize<E: Endianness>(self) -> Self::Iter;
fn split_fit_usize<E: Endianness>(self, count: u8) -> Self::Iter;
}
use std::array;
@ -288,7 +288,7 @@ macro_rules! impl_split_fit {
impl SplitFitUsize for $type {
type Iter = array::IntoIter<(usize, u8), 1>;
fn split_fit_usize<E: Endianness>(self) -> Self::Iter {
fn split_fit_usize<E: Endianness>(self, _count: u8) -> Self::Iter {
assert!(size_of::<Self>() < size_of::<usize>());
[(self as usize, size_of::<Self>() as u8 * 8)].into_iter()
}
@ -301,9 +301,9 @@ macro_rules! impl_split_fit_signed {
impl SplitFitUsize for $signed_type {
type Iter = <$unsigned_type as SplitFitUsize>::Iter;
fn split_fit_usize<E: Endianness>(self) -> Self::Iter {
fn split_fit_usize<E: Endianness>(self, count: u8) -> Self::Iter {
let unsigned = <$unsigned_type>::from_ne_bytes(self.to_ne_bytes());
unsigned.split_fit_usize::<E>()
unsigned.split_fit_usize::<E>(count)
}
}
};
@ -320,16 +320,20 @@ impl_split_fit!(u32);
impl SplitFitUsize for u32 {
type Iter = array::IntoIter<(usize, u8), 2>;
fn split_fit_usize<E: Endianness>(self) -> Self::Iter {
fn split_fit_usize<E: Endianness>(self, count: u8) -> Self::Iter {
Self::Iter::new(if E::is_le() {
[
((self & (Self::MAX >> 8)) as usize, 24),
((self >> 24) as usize, 8),
]
} else {
let offset = Self::BITS as u8 - count;
[
((self >> 24) as usize, 8),
((self & (Self::MAX >> 8)) as usize, 24),
((self >> 24) as usize, 8u8.saturating_sub(offset)),
(
(self & (Self::MAX >> 8)) as usize,
24u8.saturating_sub(offset.saturating_sub(8)),
),
]
})
}
@ -340,7 +344,7 @@ impl_split_fit_signed!(i32, u32);
impl SplitFitUsize for u64 {
type Iter = array::IntoIter<(usize, u8), 3>;
fn split_fit_usize<E: Endianness>(self) -> Self::Iter {
fn split_fit_usize<E: Endianness>(self, count: u8) -> Self::Iter {
(if E::is_le() {
[
((self & (Self::MAX >> 40)) as usize, 24),
@ -348,10 +352,17 @@ impl SplitFitUsize for u64 {
((self >> 48) as usize, 16),
]
} else {
let offset = Self::BITS as u8 - count;
[
((self >> 48) as usize, 16),
((self >> 24 & (Self::MAX >> 16)) as usize, 24),
((self & (Self::MAX >> 40)) as usize, 24),
((self >> 48) as usize, 16u8.saturating_sub(offset)),
(
(self >> 24 & (Self::MAX >> 16)) as usize,
24u8.saturating_sub(offset.saturating_sub(16)),
),
(
(self & (Self::MAX >> 40)) as usize,
24u8.saturating_sub(offset.saturating_sub(40)),
),
]
})
.into_iter()
@ -363,7 +374,7 @@ impl_split_fit_signed!(i64, u64);
impl SplitFitUsize for u128 {
type Iter = array::IntoIter<(usize, u8), 6>;
fn split_fit_usize<E: Endianness>(self) -> Self::Iter {
fn split_fit_usize<E: Endianness>(self, count: u8) -> Self::Iter {
(if E::is_le() {
[
((self & (Self::MAX >> 104)) as usize, 24),
@ -374,13 +385,29 @@ impl SplitFitUsize for u128 {
((self >> 120) as usize, 8),
]
} else {
let offset = Self::BITS as u8 - count;
[
((self >> 120) as usize, 8),
((self >> 96 & (Self::MAX >> 8)) as usize, 24),
((self >> 72 & (Self::MAX >> 32)) as usize, 24),
((self >> 48 & (Self::MAX >> 56)) as usize, 24),
((self >> 24 & (Self::MAX >> 80)) as usize, 24),
((self & (Self::MAX >> 104)) as usize, 24),
((self >> 120) as usize, 8u8.saturating_sub(offset)),
(
(self >> 96 & (Self::MAX >> 8)) as usize,
24u8.saturating_sub(offset.saturating_sub(8)),
),
(
(self >> 72 & (Self::MAX >> 32)) as usize,
24u8.saturating_sub(offset.saturating_sub(32)),
),
(
(self >> 48 & (Self::MAX >> 56)) as usize,
24u8.saturating_sub(offset.saturating_sub(56)),
),
(
(self >> 24 & (Self::MAX >> 80)) as usize,
24u8.saturating_sub(offset.saturating_sub(80)),
),
(
(self & (Self::MAX >> 104)) as usize,
24u8.saturating_sub(offset.saturating_sub(104)),
),
]
})
.into_iter()
@ -392,7 +419,7 @@ impl_split_fit_signed!(i128, u128);
impl SplitFitUsize for usize {
type Iter = array::IntoIter<(usize, u8), 2>;
fn split_fit_usize<E: Endianness>(self) -> Self::Iter {
fn split_fit_usize<E: Endianness>(self, count: u8) -> Self::Iter {
(if E::is_le() {
[
(
@ -402,11 +429,12 @@ impl SplitFitUsize for usize {
(self >> (usize::BITS - 8), 8),
]
} else {
let offset = Self::BITS as u8 - count;
[
(self >> (usize::BITS - 8), 8),
(self >> (usize::BITS - 8), 8u8.saturating_sub(offset)),
(
self & (Self::MAX >> (usize::BITS - 8)),
usize::BITS as u8 - 8,
self & (Self::MAX >> 8),
(usize::BITS as u8 - 8).saturating_sub(offset.saturating_sub(8)),
),
]
})

2
src/writestream.rs
View file

@ -193,7 +193,7 @@ where
if type_bit_size < USIZE_BITS || count <= (USIZE_BITS - (self.bit_len() % 8)) {
self.push_bits(value.into_usize_unchecked(), count);
} else {
self.push_non_fit_bits(value.split_fit_usize::<E>(), count)
self.push_non_fit_bits(value.split_fit_usize::<E>(count as u8), count)
}
Ok(())

18
tests/write_tests.rs
View file

@ -243,3 +243,21 @@ fn test_write_last_slice() {
assert_eq!(0b1000, read.read_int::<u8>(4).unwrap());
assert!(read.read_bool().unwrap());
}
#[test]
fn test_write_be_long() {
let mut bytes = vec![];
let mut writer = BitWriteStream::new(&mut bytes, BigEndian);
let num1 = 0b11000_00111110usize;
let num2 = 0b1111111_11100100_00100100_11011101_00000011_11100000_01100111_11011011usize;
writer.write_int(num1, 13).unwrap();
writer.write_int(num2, 63).unwrap();
let buffer = BitReadBuffer::new(&bytes, BigEndian);
let mut reader = BitReadStream::new(buffer);
let num1actual = reader.read_int::<usize>(13).unwrap();
let num2actual = reader.read_int::<usize>(63).unwrap();
assert_eq!(num1actual, num1);
assert_eq!(num2actual, num2);
}