tree_hash WIP

beacon_chain/utils/ssz/src/tree_hash.rs

@@ -0,0 +1,36 @@
+extern crate blake2_rfc;
+
+use self::blake2_rfc::blake2s::blake2s;
+
+/**
+ * Extends data length to a power of 2 by minimally right-zero-padding
+ */
+fn extend_to_power_of_2(data: &mut Vec<u8>) {
+    let len = data.len();
+    let new_len = len.next_power_of_two();
+    if new_len > len {
+        data.append(&mut vec![0; new_len - len]);
+    }
+}
+
+fn hash(data: Vec<u8>) -> Vec<u8> {
+    let result = blake2s(32, &[], data.as_slice());
+    result.as_bytes().to_vec()
+}
+
+// fn list_to_glob() {}
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_extend_to_power_of_2() {
+        let mut data = vec![1, 2, 3, 4, 5];
+
+        // an array length of 5 should be extended to
+        // a length of 8 (the next power of 2) by right
+        // padding it with 3 zeros
+        extend_to_power_of_2(&mut data);
+        assert_eq!(data, [1, 2, 3, 4, 5, 0, 0, 0]);
+    }
+}