Merge 0031abcebd into 4ec3be8bfa

reference_impl/reference_impl.rs

@@ -78,23 +78,14 @@ fn compress(
     block_len: u32,
     flags: u32,
 ) -> [u32; 16] {
+    let counter_low = counter as u32;
+    let counter_high = (counter >> 32) as u32;
+    #[rustfmt::skip]
     let mut state = [
-        chaining_value[0],
-        chaining_value[1],
-        chaining_value[2],
-        chaining_value[3],
-        chaining_value[4],
-        chaining_value[5],
-        chaining_value[6],
-        chaining_value[7],
-        IV[0],
-        IV[1],
-        IV[2],
-        IV[3],
-        counter as u32,
-        (counter >> 32) as u32,
-        block_len,
-        flags,
+        chaining_value[0], chaining_value[1], chaining_value[2], chaining_value[3],
+        chaining_value[4], chaining_value[5], chaining_value[6], chaining_value[7],
+        IV[0],             IV[1],             IV[2],             IV[3],
+        counter_low,       counter_high,      block_len,         flags,
     ];
     let mut block = *block_words;
 

src/lib.rs

@@ -221,6 +221,12 @@ fn counter_high(counter: u64) -> u32 {
 #[derive(Clone, Copy, Hash)]
 pub struct Hash([u8; OUT_LEN]);
 
+
+/// Provided to allow for construction of magic hash values (eg null commit in git as [0; OUT_LEN])
+pub const fn construct_magic_hash(bytes: [u8; OUT_LEN]) -> Hash {
+    Hash(bytes)
+}
+
 impl Hash {
     /// The raw bytes of the `Hash`. Note that byte arrays don't provide
     /// constant-time equality checking, so if  you need to compare hashes,