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dont store byte_len separatly

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bit_len actually makes a performance difference
This commit is contained in:
Robin Appelman 2019-07-24 12:53:45 +02:00
commit af93d0917e
2 changed files with 24 additions and 50 deletions
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53
src/buffer.rs
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@ -40,7 +40,6 @@ where
{
bytes: Rc<Vec<u8>>,
bit_len: usize,
byte_len: usize,
endianness: PhantomData<E>,
}
@ -65,7 +64,6 @@ where
let byte_len = bytes.len();
BitBuffer {
bytes: Rc::new(bytes),
byte_len,
bit_len: byte_len * 8,
endianness: PhantomData,
}
@ -83,7 +81,7 @@ where
/// The available number of bytes in the buffer
pub fn byte_len(&self) -> usize {
self.byte_len
self.bytes.len()
}
/// Panics:
@ -93,7 +91,7 @@ where
// panic instead of accessing out of bounds data when the caller didn't do it's job bounds checking
// due to the magic of branch prediction and this check "always" passing, the cost for this
// is below the point of being measurable by `cargo bench`
assert!(position + count <= self.bit_len);
assert!(position + count <= self.bit_len());
let byte_index = position / 8;
let bit_offset = position & 7;
@ -150,7 +148,7 @@ where
.get(byte_index)
.ok_or_else(|| ReadError::NotEnoughData {
requested: 1,
bits_left: self.bit_len - position,
bits_left: self.bit_len() - position,
})
.map(|byte| {
let shifted = byte >> bit_offset;
@ -199,16 +197,16 @@ where
});
}
if position + count > self.bit_len {
if position > self.bit_len {
if position + count > self.bit_len() {
if position > self.bit_len() {
return Err(ReadError::IndexOutOfBounds {
pos: position,
size: self.bit_len,
size: self.bit_len(),
});
} else {
return Err(ReadError::NotEnoughData {
requested: count,
bits_left: self.bit_len - position,
bits_left: self.bit_len() - position,
});
}
}
@ -257,7 +255,7 @@ where
where
T: PrimInt + BitOrAssign + IsSigned + UncheckedPrimitiveInt,
{
debug_assert!(position + count <= self.bit_len);
debug_assert!(position + count <= self.bit_len());
let type_bit_size = size_of::<T>() * 8;
let usize_bit_size = size_of::<usize>() * 8;
@ -286,7 +284,7 @@ where
where
T: PrimInt + BitOrAssign + IsSigned + UncheckedPrimitiveInt,
{
debug_assert!(position + count <= self.bit_len);
debug_assert!(position + count <= self.bit_len());
let type_bit_size = size_of::<T>() * 8;
let raw = self.read_usize(position, count);
@ -305,7 +303,7 @@ where
where
T: PrimInt + BitOrAssign + IsSigned + UncheckedPrimitiveInt,
{
debug_assert!(position + count <= self.bit_len);
debug_assert!(position + count <= self.bit_len());
let mut left_to_read = count;
let mut acc = T::zero();
@ -313,7 +311,7 @@ where
let mut read_pos = position;
let mut bit_offset = 0;
while left_to_read > 0 {
let bits_left = self.bit_len - read_pos;
let bits_left = self.bit_len() - read_pos;
let read = min(min(left_to_read, max_read), bits_left);
let data = T::from_unchecked(self.read_usize(read_pos, read));
if E::is_le() {
@ -373,16 +371,16 @@ where
///
/// [`ReadError::NotEnoughData`]: enum.ReadError.html#variant.NotEnoughData
pub fn read_bytes(&self, position: usize, byte_count: usize) -> Result<Vec<u8>> {
if position + byte_count * 8 > self.bit_len {
if position > self.bit_len {
if position + byte_count * 8 > self.bit_len() {
if position > self.bit_len() {
return Err(ReadError::IndexOutOfBounds {
pos: position,
size: self.bit_len,
size: self.bit_len(),
});
} else {
return Err(ReadError::NotEnoughData {
requested: byte_count * 8,
bits_left: self.bit_len - position,
bits_left: self.bit_len() - position,
});
}
}
@ -475,7 +473,7 @@ where
let mut acc = Vec::with_capacity(32);
let mut pos = position;
loop {
let read = min((USIZE_SIZE - 1) * 8, self.bit_len - pos);
let read = min((USIZE_SIZE - 1) * 8, self.bit_len() - pos);
let raw_bytes = self.read_usize(pos, read);
let bytes: [u8; USIZE_SIZE] = if E::is_le() {
raw_bytes.to_le_bytes()
@ -536,16 +534,16 @@ where
T: Float + UncheckedPrimitiveFloat,
{
let type_bit_size = size_of::<T>() * 8;
if position + type_bit_size > self.bit_len {
if position > self.bit_len {
if position + type_bit_size > self.bit_len() {
if position > self.bit_len() {
return Err(ReadError::IndexOutOfBounds {
pos: position,
size: self.bit_len,
size: self.bit_len(),
});
} else {
return Err(ReadError::NotEnoughData {
requested: size_of::<T>() * 8,
bits_left: self.bit_len - position,
bits_left: self.bit_len() - position,
});
}
}
@ -564,16 +562,15 @@ where
}
pub(crate) fn get_sub_buffer(&self, bit_len: usize) -> Result<Self> {
if bit_len > self.bit_len {
if bit_len > self.bit_len() {
return Err(ReadError::NotEnoughData {
requested: bit_len,
bits_left: self.bit_len,
bits_left: self.bit_len(),
});
}
Ok(BitBuffer {
bytes: Rc::clone(&self.bytes),
byte_len: bit_len / 8,
bit_len,
endianness: PhantomData,
})
@ -585,7 +582,6 @@ impl<E: Endianness> From<Vec<u8>> for BitBuffer<E> {
let byte_len = bytes.len();
BitBuffer {
bytes: Rc::new(bytes),
byte_len,
bit_len: byte_len * 8,
endianness: PhantomData,
}
@ -596,8 +592,7 @@ impl<E: Endianness> Clone for BitBuffer<E> {
fn clone(&self) -> Self {
BitBuffer {
bytes: Rc::clone(&self.bytes),
byte_len: self.byte_len,
bit_len: self.bit_len,
bit_len: self.bit_len(),
endianness: PhantomData,
}
}
@ -608,7 +603,7 @@ impl<E: Endianness> Debug for BitBuffer<E> {
write!(
f,
"BitBuffer {{ bit_len: {}, endianness: {} }}",
self.bit_len,
self.bit_len(),
if E::is_le() {
"LittleEndian"
} else {