Index: src/natools-s_expressions-atom_buffers.adb
==================================================================
--- src/natools-s_expressions-atom_buffers.adb
+++ src/natools-s_expressions-atom_buffers.adb
@@ -216,6 +216,30 @@
    procedure Soft_Reset (Buffer : in out Atom_Buffer) is
    begin
       Buffer.Used := 0;
    end Soft_Reset;
 
+
+   overriding procedure Write
+     (Buffer : in out Atom_Buffer;
+      Item : in Ada.Streams.Stream_Element_Array)
+     renames Append;
+
+
+   overriding procedure Read
+     (Buffer : in out Atom_Buffer;
+      Item : out Ada.Streams.Stream_Element_Array;
+      Last : out Ada.Streams.Stream_Element_Offset) is
+   begin
+      if Item'Length < Buffer.Used then
+         Last := Item'Last;
+         Item := Buffer.Ref.Query.Data.all (1 .. Item'Length);
+         Buffer.Used := Buffer.Used - Item'Length;
+      else
+         Last := Item'First + Buffer.Used - 1;
+         Item (Item'First .. Last)
+           := Buffer.Ref.Query.Data.all (1 .. Buffer.Used);
+         Buffer.Used := 0;
+      end if;
+   end Read;
+
 end Natools.S_Expressions.Atom_Buffers;

Index: src/natools-s_expressions-atom_buffers.ads
==================================================================
--- src/natools-s_expressions-atom_buffers.ads
+++ src/natools-s_expressions-atom_buffers.ads
@@ -25,13 +25,21 @@
 with Natools.S_Expressions.Atom_Refs;
 
 package Natools.S_Expressions.Atom_Buffers is
    pragma Preelaborate (Atom_Buffers);
 
-   type Atom_Buffer is tagged limited private;
+   type Atom_Buffer is new Ada.Streams.Root_Stream_Type with private;
    pragma Preelaborable_Initialization (Atom_Buffer);
 
+   overriding procedure Write
+     (Buffer : in out Atom_Buffer;
+      Item : in Ada.Streams.Stream_Element_Array);
+   overriding procedure Read
+     (Buffer : in out Atom_Buffer;
+      Item : out Ada.Streams.Stream_Element_Array;
+      Last : out Ada.Streams.Stream_Element_Offset);
+
    procedure Preallocate (Buffer : in out Atom_Buffer; Length : in Count);
       --  Preallocate enough memory to append Length octets without
       --  any further allocation.
 
    procedure Append (Buffer : in out Atom_Buffer; Data : in Atom);
@@ -69,11 +77,11 @@
    procedure Soft_Reset (Buffer : in out Atom_Buffer);
       --  Clear buffer keeping internal memory
 
 private
 
-   type Atom_Buffer is tagged limited record
+   type Atom_Buffer is new Ada.Streams.Root_Stream_Type with record
       Ref : Atom_Refs.Reference;
       Available, Used : Count := 0;
    end record;
 
 end Natools.S_Expressions.Atom_Buffers;