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-- 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. --
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-- Natools.Smaz_Implementations.Base_64_Tools provides types and primitives --
-- common to both base-64 and base-4096 variants of Smaz. --
------------------------------------------------------------------------------
with Ada.Streams;
package Natools.Smaz_Implementations.Base_64_Tools is
pragma Pure;
use type Ada.Streams.Stream_Element;
type Base_64_Digit is range 0 .. 63;
subtype Single_Byte_Padding is Base_64_Digit range 0 .. 15;
-- Padding after a single-byte partial block
subtype Double_Byte_Padding is Base_64_Digit range 0 .. 3;
-- Padding after a double-byte partial block
subtype Full_Block is String (1 .. 3);
subtype Double_Byte is String (1 .. 2);
subtype Full_Block_Image is Ada.Streams.Stream_Element_Array (1 .. 4);
subtype Double_Byte_Image is Ada.Streams.Stream_Element_Array (1 .. 3);
subtype Single_Byte_Image is Ada.Streams.Stream_Element_Array (1 .. 2);
type Base_64_Array
is array (Ada.Streams.Stream_Element_Offset range <>) of Base_64_Digit;
subtype Base_64_Symbol is Ada.Streams.Stream_Element
with Static_Predicate => Base_64_Symbol in
Character'Pos ('A') .. Character'Pos ('Z')
| Character'Pos ('a') .. Character'Pos ('z')
| Character'Pos ('0') .. Character'Pos ('9')
| Character'Pos ('+') | Character'Pos ('/');
function Image (Digit : in Base_64_Digit) return Ada.Streams.Stream_Element
is (case Digit is
when 0 .. 25
=> Character'Pos ('A') + Ada.Streams.Stream_Element (Digit) - 0,
when 26 .. 51
=> Character'Pos ('a') + Ada.Streams.Stream_Element (Digit) - 26,
when 52 .. 61
=> Character'Pos ('0') + Ada.Streams.Stream_Element (Digit) - 52,
when 62 => Character'Pos ('+'),
when 63 => Character'Pos ('/'));
-- Printable character representation of Digit
function Value (Symbol : in Base_64_Symbol) return Base_64_Digit
is (case Symbol is
when Character'Pos ('A') .. Character'Pos ('Z')
=> Base_64_Digit (Symbol - Character'Pos ('A') + 0),
when Character'Pos ('a') .. Character'Pos ('z')
=> Base_64_Digit (Symbol - Character'Pos ('a') + 26),
when Character'Pos ('0') .. Character'Pos ('9')
=> Base_64_Digit (Symbol - Character'Pos ('0') + 52),
when Character'Pos ('+') => 62,
when Character'Pos ('/') => 63);
-- Value represented by a symbol
function Image_Length (Input_Length : in Natural)
return Ada.Streams.Stream_Element_Count
is (Ada.Streams.Stream_Element_Count
(Input_Length + (Input_Length + 2) / 3));
-- Paddingless encoded length
function Value_Length (Input_Length : in Ada.Streams.Stream_Element_Count)
return Natural
is (Natural (Input_Length) - (Natural (Input_Length) + 3) / 4);
-- Original length of an encoded array
function Symbol_Count (Input : Ada.Streams.Stream_Element_Array)
return Ada.Streams.Stream_Element_Count;
-- Return the number of valid symbols in Input
procedure Encode
(Input : in String;
Output : in out Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset);
-- Paddingless raw encoding of Input data
procedure Decode
(Input : in Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Output : out String);
-- Paddingless raw decoding of Input data
procedure Encode_Block
(Input : in Full_Block;
Output : in out Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset);
procedure Encode_Double
(Input : in Double_Byte;
Padding : in Double_Byte_Padding;
Output : in out Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset);
procedure Encode_Single
(Input : in Character;
Padding : in Single_Byte_Padding;
Output : in out Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset);
-- Encode a complete or partial block into Output at Offset
procedure Decode_Block
(Input : in Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Output : out Full_Block);
procedure Decode_Double
(Input : in Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Output : out Double_Byte;
Padding : out Double_Byte_Padding);
procedure Decode_Single
(Input : in Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Output : out Character;
Padding : out Single_Byte_Padding);
procedure Next_Digit
(Input : in Ada.Streams.Stream_Element_Array;
Offset : in out Ada.Streams.Stream_Element_Offset;
Digit : out Base_64_Digit);
-- Look for the first valid symbol in Input from Offset, and decode it
end Natools.Smaz_Implementations.Base_64_Tools;