Added reset_hash

src/cyclic_poly.rs

@@ -84,6 +84,12 @@ impl<T: HashValue> CyclicPoly<T> {
         self.current
     }
 
+    /// Reset the current hash value.
+    /// This does not reset the block size. To reset the block size create a new object.
+    pub fn reset_hash(&mut self) {
+        self.current = T::zero()
+    }
+
     /// Calculate a single hash value from the given block.
     /// This function does not support rolling hashes but saves the initial
     /// setup that is done when calling new().
@@ -161,10 +167,20 @@ impl<T: HashValue> CyclicPoly<T> {
 
 #[cfg(test)]
 mod tests {
-    use crate::{cyclic_poly::CyclicPoly, hash_value::HashValue};
+    use crate::{cyclic_poly::CyclicPoly, hash_value::HashValue, CyclicPoly32};
     use quickcheck::TestResult;
     use quickcheck_macros::quickcheck;
 
+    #[test]
+    fn reset_hash() {
+        let data = vec![0, 1, 2, 3, 4, 5, 6, 7];
+        let mut h = CyclicPoly32::from_block(&data);
+        let expected = h.value();
+        h.reset_hash();
+        let actual = h.update(&data);
+        assert_eq!(expected, actual);
+    }
+
     #[quickcheck]
     fn sensitivity64(data0: Vec<u8>, i: usize) -> TestResult {
         sensitivity_check::<u64>(data0, i)