[Ada] Add support for returning binary message digest

[Arnaud Charlet]

If a binary digest is needed it is a waste of time to recompute
it from the string encoded digest.

Tested on x86_64-pc-linux-gnu, committed on trunk

2012-10-29  Pascal Obry  <obry@adacore.com>

	* g-sechas.adb, g-sechas.ads: (Binary_Message_Digest): New subtype.
	(Digest): New versions returning a Binary_Message_Digest.
	(Wide_Digest): Likewise.

-------------- next part --------------
Index: g-sechas.adb
===================================================================
--- g-sechas.adb	(revision 192920)
+++ g-sechas.adb	(working copy)
@@ -184,6 +184,30 @@
          return Digest (C);
       end Digest;
 
+      function Digest (C : Context) return Binary_Message_Digest is
+         Hash_Bits : Stream_Element_Array
+                       (1 .. Stream_Element_Offset (Hash_Length));
+      begin
+         Final (C, Hash_Bits);
+         return Hash_Bits;
+      end Digest;
+
+      function Digest (S : String) return Binary_Message_Digest is
+         C : Context;
+      begin
+         Update (C, S);
+         return Digest (C);
+      end Digest;
+
+      function Digest
+        (A : Stream_Element_Array) return Binary_Message_Digest
+      is
+         C : Context;
+      begin
+         Update (C, A);
+         return Digest (C);
+      end Digest;
+
       -----------
       -- Final --
       -----------
@@ -325,6 +349,13 @@
          return Digest (C);
       end Wide_Digest;
 
+      function Wide_Digest (W : Wide_String) return Binary_Message_Digest is
+         C : Context;
+      begin
+         Wide_Update (C, W);
+         return Digest (C);
+      end Wide_Digest;
+
    end H;
 
    -------------------------
Index: g-sechas.ads
===================================================================
--- g-sechas.ads	(revision 192920)
+++ g-sechas.ads	(working copy)
@@ -156,6 +156,22 @@
       Word_Length : constant Natural := Hash_State.Word'Size / 8;
       Hash_Length : constant Natural := Hash_Words * Word_Length;
 
+      subtype Binary_Message_Digest is
+        Stream_Element_Array (1 .. Stream_Element_Offset (Hash_Length));
+      --  The fixed-length byte array returned by Digest, providing
+      --  the hash in binary representation.
+
+      function Digest (C : Context) return Binary_Message_Digest;
+      --  Return hash for the data accumulated with C
+
+      function Digest      (S : String)      return Binary_Message_Digest;
+      function Wide_Digest (W : Wide_String) return Binary_Message_Digest;
+      function Digest
+        (A : Stream_Element_Array) return Binary_Message_Digest;
+      --  These functions are equivalent to the corresponding Update (or
+      --  Wide_Update) on a default initialized Context, followed by Digest
+      --  on the resulting Context.
+
       subtype Message_Digest is String (1 .. 2 * Hash_Length);
       --  The fixed-length string returned by Digest, providing the hash in
       --  hexadecimal representation.