Add example/xxh128_from_xxh64.cpp

example/Jamfile

@@ -12,3 +12,4 @@ exe hash_with_uint64_seed : hash_with_uint64_seed.cpp ;
 exe hash_with_byte_seed : hash_with_byte_seed.cpp ;
 exe hash_with_any_seed : hash_with_any_seed.cpp ;
 exe hash_32_64 : hash_32_64.cpp ;
+exe xxh128_from_xxh64 : xxh128_from_xxh64.cpp ;

example/xxh128_from_xxh64.cpp

@@ -0,0 +1,43 @@
+// Copyright 2024 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/hash2/xxhash.hpp>
+#include <boost/hash2/digest.hpp>
+#include <boost/endian/conversion.hpp>
+
+class xxhash_128: private boost::hash2::xxhash_64
+{
+public:
+
+    using result_type = boost::hash2::digest<16>;
+
+    using xxhash_64::xxhash_64;
+    using xxhash_64::update;
+
+    result_type result()
+    {
+        std::uint64_t r1 = xxhash_64::result();
+        std::uint64_t r2 = xxhash_64::result();
+
+        result_type r = {};
+
+        boost::endian::store_little_u64( r.data() + 0, r1 );
+        boost::endian::store_little_u64( r.data() + 8, r2 );
+
+        return r;
+    }
+};
+
+#include <string>
+#include <iostream>
+
+int main()
+{
+    std::string tv( "The quick brown fox jumps over the lazy dog" );
+
+    xxhash_128 hash( 43 );
+    hash.update( tv.data(), tv.size() );
+
+    std::cout << hash.result() << std::endl;
+}

test/Jamfile

@@ -170,3 +170,4 @@ link ../example/hash_with_uint64_seed.cpp ;
 link ../example/hash_with_byte_seed.cpp ;
 link ../example/hash_with_any_seed.cpp ;
 link ../example/hash_32_64.cpp ;
+link ../example/xxh128_from_xxh64.cpp ;