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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) } }