fix: logic error in encode_unaligned_chunks

src/arch/generic.rs

@@ -32,16 +32,17 @@ pub(crate) unsafe fn encode_unaligned_chunks<const UPPER: bool, T: Copy>(
     mut encode_chunk: impl FnMut(T) -> (T, T),
 ) {
     let (chunks, remainder) = chunks_unaligned::<T>(input);
-    let remainder_i = chunks.len() * core::mem::size_of::<T>();
+    let n_in_chunks = chunks.len();
     let chunk_output = output.cast::<T>();
     for (i, chunk) in chunks.enumerate() {
         let (lo, hi) = encode_chunk(chunk);
         unsafe {
             chunk_output.add(i * 2).write_unaligned(lo);
-            chunk_output.add((i * 2) + 1).write_unaligned(hi);
+            chunk_output.add(i * 2 + 1).write_unaligned(hi);
         }
     }
-    unsafe { encode::<UPPER>(remainder, unsafe { output.add(remainder_i) }) };
+    let n_out_chunks = n_in_chunks * 2;
+    unsafe { encode::<UPPER>(remainder, unsafe { chunk_output.add(n_out_chunks).cast() }) };
 }
 
 /// Default check function.

src/lib.rs

@@ -719,7 +719,7 @@ pub mod fuzzing {
     use super::*;
     use proptest::test_runner::TestCaseResult;
     use proptest::{prop_assert, prop_assert_eq};
-    use std::io::Write;
+    use std::fmt::Write;
 
     pub fn fuzz(data: &[u8]) -> TestCaseResult {
         self::encode(&data)?;
@@ -754,11 +754,11 @@ pub mod fuzzing {
     }
 
     fn mk_expected(bytes: &[u8]) -> String {
-        let mut s = Vec::with_capacity(bytes.len() * 2);
+        let mut s = String::with_capacity(bytes.len() * 2);
         for i in bytes {
             write!(s, "{i:02x}").unwrap();
         }
-        unsafe { String::from_utf8_unchecked(s) }
+        s
     }
 
     fn test_buffer<const N: usize, const LEN: usize>(bytes: &[u8]) -> TestCaseResult {

tests/test.rs

@@ -112,10 +112,27 @@ fn decode_upper() {
 
 #[test]
 #[cfg(feature = "alloc")]
-fn decode_long() {
-    let s = "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";
-    const_hex::check(s).unwrap();
-    assert_eq!(const_hex::decode(s).unwrap(), hex::decode(s).unwrap());
+fn roundtrips() {
+    test_roundtrip("1234");
+    test_roundtrip("00000000000011");
+    test_roundtrip("0000000000000022");
+    test_roundtrip("000000000000000033");
+    test_roundtrip("00000000000000003344");
+    test_roundtrip("05161049138038061049183398181016");
+}
+
+#[test]
+#[cfg(feature = "alloc")]
+fn roundtrip_long() {
+    test_roundtrip("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");
+}
+
+#[cfg(feature = "alloc")]
+fn test_roundtrip(s: &str) {
+    const_hex::check(s).expect(s);
+    let decoded = const_hex::decode(s).expect(s);
+    assert_eq!(decoded, hex::decode(s).expect(s));
+    assert_eq!(const_hex::encode(&decoded), s);
 }
 
 #[test]