From 71c71783d4efa7f44af910daf015e6972f069472 Mon Sep 17 00:00:00 2001
From: edef <edef@unfathomable.blue>
Date: Mon, 2 May 2022 01:43:33 +0000
Subject: ripple/fossil/chunker: factor out Chunker::cut

Change-Id: I4fed55703cd02833f377ed0bbc659f3fcfdb949f
---
 ripple/fossil/src/chunker/mod.rs | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

(limited to 'ripple/fossil')

diff --git a/ripple/fossil/src/chunker/mod.rs b/ripple/fossil/src/chunker/mod.rs
index 9172a15..16e81a2 100644
--- a/ripple/fossil/src/chunker/mod.rs
+++ b/ripple/fossil/src/chunker/mod.rs
@@ -25,6 +25,16 @@ impl<'a> Chunker<'a> {
 	pub fn from(buffer: &'a [u8]) -> Chunker<'a> {
 		Chunker { 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> {
@@ -39,38 +49,28 @@ impl<'a> Iterator for Chunker<'a> {
 		}
 
 		let bytes = self.buffer.iter().take(MAX_CHUNK_SIZE).skip(MIN_CHUNK_SIZE);
-
 		let mut hasher = buz::Rolling::<WINDOW_SIZE>::from_slice(&self.buffer[..MIN_CHUNK_SIZE]);
-		let chunk;
 		for byte in bytes {
 			let buz::Hash(x) = hasher.sum();
 			if x % DISCRIMINATOR == DISCRIMINATOR.wrapping_sub(1) {
 				// split point
-				(chunk, self.buffer) = unsafe {
+				return Some(unsafe {
 					// SAFETY: `byte` is in bounds of `self.buffer`, so
 					// computing `idx` is safe, and `idx` is in bounds
 					let origin = self.buffer.as_ptr();
 					let ptr = byte as *const u8;
 					let idx = ptr.offset_from(origin) as usize;
-					(
-						self.buffer.get_unchecked(..idx),
-						self.buffer.get_unchecked(idx..),
-					)
-				};
-				return Some(chunk);
+					self.cut(idx)
+				});
 			}
 			hasher.push(*byte);
 		}
 
-		(chunk, self.buffer) = unsafe {
-			// SAFETY: `mid` is clamped to `self.buffer.len()`
-			let mid = MAX_CHUNK_SIZE.min(self.buffer.len());
-			(
-				self.buffer.get_unchecked(..mid),
-				self.buffer.get_unchecked(mid..),
-			)
-		};
-		Some(chunk)
+		Some(unsafe {
+			// SAFETY: `idx` is clamped to `self.buffer.len()`
+			let idx = MAX_CHUNK_SIZE.min(self.buffer.len());
+			self.cut(idx)
+		})
 	}
 
 	fn size_hint(&self) -> (usize, Option<usize>) {
-- 
cgit 1.4.1