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pad the buffer to simplify read logic

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Robin Appelman 2020-01-06 18:44:25 +01:00
commit ccc48f1bdb
1 changed files with 8 additions and 12 deletions
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20
src/buffer.rs
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@ -61,8 +61,11 @@ where
/// ]; /// ];
/// let buffer = BitBuffer::new(bytes, LittleEndian); /// let buffer = BitBuffer::new(bytes, LittleEndian);
/// ``` /// ```
pub fn new(bytes: Vec<u8>, _endianness: E) -> Self { pub fn new(mut bytes: Vec<u8>, _endianness: E) -> Self {
let byte_len = bytes.len(); let byte_len = bytes.len();
// pad with usize worth of bytes to ensure we can always read a full usize
bytes.extend_from_slice(&0usize.to_le_bytes());
BitBuffer { BitBuffer {
bytes: Rc::new(bytes), bytes: Rc::new(bytes),
bit_len: byte_len * 8, bit_len: byte_len * 8,
@ -86,16 +89,9 @@ where
} }
fn read_usize_bytes(&self, byte_index: usize) -> [u8; USIZE_SIZE] { fn read_usize_bytes(&self, byte_index: usize) -> [u8; USIZE_SIZE] {
if byte_index + USIZE_SIZE <= self.bytes.len() { self.bytes[byte_index..byte_index + USIZE_SIZE]
self.bytes[byte_index..byte_index + USIZE_SIZE] .try_into()
.try_into() .unwrap()
.unwrap()
} else {
let mut bytes = [0; USIZE_SIZE];
let copy_bytes = self.bytes.len() - byte_index;
bytes[0..copy_bytes].copy_from_slice(&self.bytes[byte_index..byte_index + copy_bytes]);
bytes
}
} }
/// note that only the bottom USIZE - 1 bytes are usable /// note that only the bottom USIZE - 1 bytes are usable
@ -424,7 +420,7 @@ where
fn find_null_byte(&self, byte_index: usize) -> usize { fn find_null_byte(&self, byte_index: usize) -> usize {
memchr::memchr(0, &self.bytes[byte_index..]) memchr::memchr(0, &self.bytes[byte_index..])
.map(|index| index + byte_index) .map(|index| index + byte_index)
.unwrap_or(self.byte_len()) .unwrap() // due to padding we always have 0 bytes at the end
} }
#[inline] #[inline]