manually implement addition-by-one

The int conversion is quite costly, so this is a lot faster (especially
in the non-simd build).

1 files changed, 4 insertions, 4 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 919e91b..f327959 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -705,17 +705,17 @@ fn aez_hash(aez: &Aez, tweaks: Tweak) -> Block {
 
 /// XOR's the result of aez_prf into the given buffer
 fn aez_prf(aez: &Aez, tweaks: Tweak, buffer: &mut [u8]) {
-    let mut index = 0u128;
+    let mut index = Block::null();
     let delta = aez_hash(aez, tweaks);
     for chunk in buffer.chunks_exact_mut(16) {
         let chunk: &mut [u8; 16] = chunk.try_into().unwrap();
-        let block = e(-1, 3, aez, delta ^ Block::from_int(index));
+        let block = e(-1, 3, aez, delta ^ index);
         (block ^ Block::from(*chunk)).write_to(chunk);
-        index += 1;
+        index.count_up();
     }
     let suffix_start = buffer.len() - buffer.len() % 16;
     let chunk = &mut buffer[suffix_start..];
-    let block = e(-1, 3, aez, delta ^ Block::from_int(index));
+    let block = e(-1, 3, aez, delta ^ index);
     for (a, b) in chunk.iter_mut().zip(block.bytes().iter()) {
         *a ^= *b;
     }