Merge pull request #68 from jhpratt/master

Optimize 128-bit integer formatting

Author: dtolnay

src/lib.rs

@@ -410,7 +410,7 @@ fn enc_16lsd<const OFFSET: usize>(buf: &mut [MaybeUninit<u8>], n: u64) {
     let mut remain = n;
 
     // Format per four digits from the lookup table.
-    for quad_index in (0..4).rev() {
+    for quad_index in (1..4).rev() {
         // pull two pairs
         let quad = remain % 1_00_00;
         remain /= 1_00_00;
@@ -426,6 +426,15 @@ fn enc_16lsd<const OFFSET: usize>(buf: &mut [MaybeUninit<u8>], n: u64) {
                 .write(*DECIMAL_PAIRS.0.get_unchecked(pair2 as usize * 2 + 1));
         }
     }
+
+    // final two pairs
+    let (pair1, pair2) = divmod100(remain as u32);
+    unsafe {
+        buf[OFFSET + 0].write(*DECIMAL_PAIRS.0.get_unchecked(pair1 as usize * 2 + 0));
+        buf[OFFSET + 1].write(*DECIMAL_PAIRS.0.get_unchecked(pair1 as usize * 2 + 1));
+        buf[OFFSET + 2].write(*DECIMAL_PAIRS.0.get_unchecked(pair2 as usize * 2 + 0));
+        buf[OFFSET + 3].write(*DECIMAL_PAIRS.0.get_unchecked(pair2 as usize * 2 + 1));
+    }
 }
 
 // Euclidean division plus remainder with constant 1E16 basically consumes 16