------------------------------------------------------------------------------
-- Copyright (c) 2016, Natacha Porté --
-- --
-- Permission to use, copy, modify, and distribute this software for any --
-- purpose with or without fee is hereby granted, provided that the above --
-- copyright notice and this permission notice appear in all copies. --
-- --
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES --
-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF --
-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR --
-- ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES --
-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN --
-- ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF --
-- OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. --
------------------------------------------------------------------------------
package body Natools.Smaz_Implementations.Base_256 is
use type Ada.Streams.Stream_Element;
use type Ada.Streams.Stream_Element_Offset;
procedure Read_Code
(Input : in Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Code : out Ada.Streams.Stream_Element;
Verbatim_Length : out Natural;
Last_Code : in Ada.Streams.Stream_Element;
Variable_Length_Verbatim : in Boolean)
is
Input_Byte : constant Ada.Streams.Stream_Element := Input (Offset);
begin
if Input_Byte <= Last_Code then
Code := Input_Byte;
Verbatim_Length := 0;
else
Code := 0;
if not Variable_Length_Verbatim then
Verbatim_Length
:= Positive (Ada.Streams.Stream_Element'Last - Input_Byte) + 1;
elsif Input_Byte < Ada.Streams.Stream_Element'Last then
Verbatim_Length
:= Positive (Ada.Streams.Stream_Element'Last - Input_Byte);
else
Offset := Offset + 1;
Verbatim_Length
:= Positive (Input (Offset))
+ Natural (Ada.Streams.Stream_Element'Last - Last_Code)
- 1;
end if;
end if;
Offset := Offset + 1;
end Read_Code;
procedure Read_Verbatim
(Input : in Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Output : out String) is
begin
for I in Output'Range loop
Output (I) := Character'Val (Input (Offset));
Offset := Offset + 1;
end loop;
end Read_Verbatim;
procedure Skip_Verbatim
(Input : in Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Verbatim_Length : in Positive)
is
pragma Unreferenced (Input);
begin
Offset := Offset + Ada.Streams.Stream_Element_Offset (Verbatim_Length);
end Skip_Verbatim;
function Verbatim_Size
(Input_Length : in Positive;
Last_Code : in Ada.Streams.Stream_Element;
Variable_Length_Verbatim : in Boolean)
return Ada.Streams.Stream_Element_Count
is
Verbatim1_Max_Size : constant Ada.Streams.Stream_Element_Count
:= Ada.Streams.Stream_Element_Count
(Ada.Streams.Stream_Element'Last - Last_Code)
- Boolean'Pos (Variable_Length_Verbatim);
Verbatim2_Max_Size : constant Ada.Streams.Stream_Element_Count
:= Ada.Streams.Stream_Element_Count (Ada.Streams.Stream_Element'Last)
+ Verbatim1_Max_Size;
Remaining : Ada.Streams.Stream_Element_Count
:= Ada.Streams.Stream_Element_Count (Input_Length);
Overhead : Ada.Streams.Stream_Element_Count := 0;
begin
if Variable_Length_Verbatim then
if Remaining >= Verbatim2_Max_Size then
declare
Full_Blocks : constant Ada.Streams.Stream_Element_Count
:= Remaining / Verbatim2_Max_Size;
begin
Overhead := Overhead + 2 * Full_Blocks;
Remaining := Remaining - Verbatim2_Max_Size * Full_Blocks;
end;
end if;
if Remaining > Verbatim1_Max_Size then
Overhead := Overhead + 2;
Remaining := 0;
end if;
end if;
declare
Full_Blocks : constant Ada.Streams.Stream_Element_Count
:= Remaining / Verbatim1_Max_Size;
begin
Overhead := Overhead + Full_Blocks;
end;
return Overhead + Ada.Streams.Stream_Element_Count (Input_Length);
end Verbatim_Size;
procedure Write_Code
(Output : in out Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Code : in Ada.Streams.Stream_Element) is
begin
Output (Offset) := Code;
Offset := Offset + 1;
end Write_Code;
procedure Write_Verbatim
(Output : in out Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Input : in String;
Last_Code : in Ada.Streams.Stream_Element;
Variable_Length_Verbatim : in Boolean)
is
Verbatim1_Max_Size : constant Natural
:= Natural (Ada.Streams.Stream_Element'Last - Last_Code)
- Boolean'Pos (Variable_Length_Verbatim);
Verbatim2_Max_Size : constant Natural
:= Natural (Ada.Streams.Stream_Element'Last)
+ Verbatim1_Max_Size;
Input_Index : Positive := Input'First;
Remaining_Length, Block_Length : Positive;
begin
while Input_Index in Input'Range loop
Remaining_Length := Input'Last - Input_Index + 1;
if Variable_Length_Verbatim
and then Remaining_Length > Verbatim1_Max_Size
then
Block_Length := Positive'Min
(Remaining_Length, Verbatim2_Max_Size);
Output (Offset) := Ada.Streams.Stream_Element'Last;
Output (Offset + 1) := Ada.Streams.Stream_Element
(Block_Length - Verbatim1_Max_Size);
Offset := Offset + 2;
else
Block_Length := Positive'Min
(Remaining_Length, Verbatim1_Max_Size);
Output (Offset)
:= Ada.Streams.Stream_Element'Last
- Ada.Streams.Stream_Element
(Block_Length - 1 + Boolean'Pos (Variable_Length_Verbatim));
Offset := Offset + 1;
end if;
Verbatim_Copy :
for I in 1 .. Block_Length loop
Output (Offset) := Character'Pos (Input (Input_Index));
Offset := Offset + 1;
Input_Index := Input_Index + 1;
end loop Verbatim_Copy;
end loop;
end Write_Verbatim;
end Natools.Smaz_Implementations.Base_256;