1 files changed, 20 insertions, 0 deletions
diff --git a/serialize/packbits-write.hpp b/serialize/packbits-write.hpp
index 4741a462..7b69069a 100644
--- a/serialize/packbits-write.hpp
+++ b/serialize/packbits-write.hpp
@@ -3,6 +3,26 @@
 
 namespace floormat::detail_Pack {
 
+template<std::unsigned_integral T, size_t CAPACITY>
+struct output
+{
+    static_assert(CAPACITY <= sizeof(T)*8);
+    static constexpr size_t Capacity = CAPACITY;
+    T value;
 
+    template<size_t N>
+    constexpr void set(T x) const
+    {
+        static_assert(N > 0);
+        static_assert(N <= sizeof(T)*8);
+        static_assert(N <= Capacity);
+        if constexpr(CAPACITY < sizeof(T)*8)
+            value <<= CAPACITY;
+        T x_ = T(x & (1 << N)-1);
+        fm_assert(x_ == x);
+        value |= x;
+    }
+    template<size_t N> using next = output<T, CAPACITY - N>;
+};
 
 } // namespace floormat::detail_Pack