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Diffstat (limited to 'third_party/cachunker/src/lib.rs')
-rw-r--r-- | third_party/cachunker/src/lib.rs | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/third_party/cachunker/src/lib.rs b/third_party/cachunker/src/lib.rs new file mode 100644 index 0000000..10c7f00 --- /dev/null +++ b/third_party/cachunker/src/lib.rs @@ -0,0 +1,81 @@ +// SPDX-FileCopyrightText: edef <edef@unfathomable.blue> +// SPDX-License-Identifier: LGPL-2.1-or-later + +use std::mem; + +pub struct Chunker<'a> { + state: sys::CaChunker, + buffer: &'a [u8], +} + +impl<'a> Chunker<'a> { + pub fn from(buffer: &'a [u8]) -> Self { + Self { + state: sys::CaChunker::new(), + buffer, + } + } + + /// SAFETY: `idx` must be an in-bounds index for `self.buffer` + unsafe fn cut(&mut self, idx: usize) -> &'a [u8] { + let ret; + (ret, self.buffer) = ( + self.buffer.get_unchecked(..idx), + self.buffer.get_unchecked(idx..), + ); + ret + } +} + +impl<'a> Iterator for Chunker<'a> { + type Item = &'a [u8]; + fn next(&mut self) -> Option<Self::Item> { + if self.buffer.is_empty() { + return None; + } + + Some(match self.state.scan(self.buffer) { + Some(n) => unsafe { self.cut(n) }, + None => mem::take(&mut self.buffer), + }) + } +} + +mod sys { + #[repr(C)] + #[derive(Clone)] + pub struct CaChunker { + h: u32, + + window_size: usize, + chunk_size: usize, + + chunk_size_min: usize, + chunk_size_max: usize, + chunk_size_avg: usize, + + discriminator: usize, + + window: [u8; 48], + } + + impl CaChunker { + pub fn new() -> CaChunker { + unsafe { &ca_chunker_init }.clone() + } + + pub fn scan(&mut self, data: &[u8]) -> Option<usize> { + unsafe { + match ca_chunker_scan(self, data.as_ptr(), data.len()) { + usize::MAX => None, + n => Some(n), + } + } + } + } + + extern "C" { + static ca_chunker_init: CaChunker; + fn ca_chunker_scan(c: *mut CaChunker, p: *const u8, n: usize) -> usize; + } +} |