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// Unless explicitly stated otherwise all files in this repository are licensed
// under the MIT/Apache-2.0 License, at your convenience
//
// This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2020 Datadog, Inc.
/// Utility methods for working with byte slices/buffers.
pub trait ByteSliceExt {
/// Copies the contents of `self` into the byte-slice `destination`.
///
/// The copy starts at position `offset` into the `source` and copies
/// as many bytes as possible until either we don't have more bytes to copy
/// or `destination` doesn't have more space to hold them.
///
/// ## Returns
///
/// The amount of bytes written.
///
/// # Examples
///
/// ```no_run
/// use glommio::{io::DmaFile, ByteSliceExt, LocalExecutor};
///
/// let ex = LocalExecutor::default();
/// ex.run(async {
/// let file = DmaFile::create("test.txt").await.unwrap();
/// let buf = file.alloc_dma_buffer(4096);
/// let mut vec = vec![0; 64];
/// let n = buf.read_at(0, &mut vec);
/// assert_eq!(n, 64); // read 64 bytes, the size of the buffer
///
/// let n = buf.read_at(4090, &mut vec);
/// assert_eq!(n, 6); // read 6 bytes, as there are only 6 bytes left from this offset
/// file.close().await.unwrap();
/// });
/// ```
fn read_at<D: AsMut<[u8]> + ?Sized>(&self, offset: usize, destination: &mut D) -> usize;
}
/// Utility methods for working with mutable byte slices/buffers.
pub trait ByteSliceMutExt {
/// Writes data to this buffer from a user-provided byte slice, starting at
/// a particular offset
///
/// ## Returns
///
/// The amount of bytes written.
///
/// # Examples
///
/// ```no_run
/// use glommio::{io::DmaFile, ByteSliceMutExt, LocalExecutor};
///
/// let ex = LocalExecutor::default();
/// ex.run(async {
/// let file = DmaFile::create("test.txt").await.unwrap();
/// let mut buf = file.alloc_dma_buffer(4096);
/// let vec = vec![1; 64];
/// let n = buf.write_at(0, &vec);
/// assert_eq!(n, 64); // wrote 64 bytes.
///
/// let n = buf.write_at(4090, &vec);
/// assert_eq!(n, 6); // wrote 6 bytes, as there are only 6 bytes left from this offset
/// file.close().await.unwrap();
/// });
/// ```
fn write_at<S: AsRef<[u8]> + ?Sized>(&mut self, offset: usize, src: &S) -> usize;
/// Writes the specified value into all bytes of this buffer
fn memset(&mut self, value: u8);
}
#[inline]
fn slice_read_at(source: &[u8], offset: usize, destination: &mut [u8]) -> usize {
if offset > source.len() {
0
} else {
let len = core::cmp::min(destination.len(), source.len() - offset);
destination[0..len].copy_from_slice(&source[offset..][..len]);
len
}
}
#[inline]
fn slice_write_at(destination: &mut [u8], offset: usize, source: &[u8]) -> usize {
if offset > destination.len() {
0
} else {
let len = std::cmp::min(source.len(), destination.len() - offset);
destination[offset..offset + len].copy_from_slice(&source[0..len]);
len
}
}
#[inline]
fn slice_memset(destination: &mut [u8], value: u8) {
for b in destination.iter_mut() {
*b = value;
}
}
// A NOTE about `#[inline]`: rustc currently only inlines code *across crate
// boundaries* if it is marked with `#[inline]`.
impl<T: AsRef<[u8]> + ?Sized> ByteSliceExt for T {
#[inline]
fn read_at<D: AsMut<[u8]> + ?Sized>(&self, offset: usize, destination: &mut D) -> usize {
slice_read_at(self.as_ref(), offset, destination.as_mut())
}
}
impl<T: AsMut<[u8]> + ?Sized> ByteSliceMutExt for T {
#[inline]
fn write_at<S: AsRef<[u8]> + ?Sized>(&mut self, offset: usize, src: &S) -> usize {
slice_write_at(self.as_mut(), offset, src.as_ref())
}
#[inline]
fn memset(&mut self, value: u8) {
slice_memset(self.as_mut(), value)
}
}