1 files changed, 72 insertions, 0 deletions
diff --git a/third_party/rust/deflate/src/checksum.rs b/third_party/rust/deflate/src/checksum.rs
new file mode 100644
index 0000000000..e1885a210f
--- /dev/null
+++ b/third_party/rust/deflate/src/checksum.rs
@@ -0,0 +1,72 @@
+use adler32::RollingAdler32;
+
+pub trait RollingChecksum {
+    fn update(&mut self, byte: u8);
+    fn update_from_slice(&mut self, data: &[u8]);
+    fn current_hash(&self) -> u32;
+}
+
+pub struct NoChecksum {}
+
+impl NoChecksum {
+    pub fn new() -> NoChecksum {
+        NoChecksum {}
+    }
+}
+
+impl RollingChecksum for NoChecksum {
+    fn update(&mut self, _: u8) {}
+    fn update_from_slice(&mut self, _: &[u8]) {}
+    fn current_hash(&self) -> u32 {
+        1
+    }
+}
+
+impl<'a> RollingChecksum for &'a mut NoChecksum {
+    fn update(&mut self, _: u8) {}
+    fn update_from_slice(&mut self, _: &[u8]) {}
+    fn current_hash(&self) -> u32 {
+        1
+    }
+}
+
+pub struct Adler32Checksum {
+    adler32: RollingAdler32,
+}
+
+impl Adler32Checksum {
+    pub fn new() -> Adler32Checksum {
+        Adler32Checksum {
+            adler32: RollingAdler32::new(),
+        }
+    }
+}
+
+impl RollingChecksum for Adler32Checksum {
+    fn update(&mut self, byte: u8) {
+        self.adler32.update(byte);
+    }
+
+    fn update_from_slice(&mut self, data: &[u8]) {
+        self.adler32.update_buffer(data);
+    }
+
+    fn current_hash(&self) -> u32 {
+        self.adler32.hash()
+    }
+}
+
+
+impl<'a> RollingChecksum for &'a mut Adler32Checksum {
+    fn update(&mut self, byte: u8) {
+        self.adler32.update(byte);
+    }
+
+    fn update_from_slice(&mut self, data: &[u8]) {
+        self.adler32.update_buffer(data);
+    }
+
+    fn current_hash(&self) -> u32 {
+        self.adler32.hash()
+    }
+}