approach 2

Author: grisumbras

include/boost/json/detail/digest.hpp

@@ -32,21 +32,17 @@ digest(
 #endif
     hash += salt;
 
-    constexpr std::size_t step = sizeof(std::size_t);
-    std::size_t const m = n - (n % step);
-    n -= m;
-
-    char const* const end = s + m;
-    for(; s < end; s += step)
+    char const* const end = s + n;
+    for(;s < end;)
     {
-        std::size_t batch;
+        std::size_t step = (std::min)(sizeof(std::size_t),
+            static_cast<std::size_t>(end - s));
+        std::size_t batch = 0;
         std::memcpy(&batch, s, step);
         hash = (batch ^ hash) * prime;
+        s += step;
     }
 
-    for (; s < end + n; ++s)
-        hash = (*s ^ hash) * prime;
-
     return hash;
 }