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119 | -----------------------------------------------------------------------
-- util-encoders-base16 -- Encode/Decode a stream in hexadecimal
-- Copyright (C) 2009, 2010, 2011, 2017, 2022 Stephane Carrez
-- Written by Stephane Carrez (Stephane.Carrez@gmail.com)
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
-- http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
-----------------------------------------------------------------------
with Ada.Streams;
-- The <b>Util.Encodes.Base16</b> packages encodes and decodes streams
-- in hexadecimal.
package Util.Encoders.Base16 is
pragma Preelaborate;
use type Interfaces.Unsigned_8;
Conversion : constant String (1 .. 16) := "0123456789ABCDEF";
function From_Hex (C : in Character) return Interfaces.Unsigned_8 is
(if C >= '0' and then C <= '9' then Character'Pos (C) - Character'Pos ('0')
elsif C >= 'A' and then C <= 'F' then Character'Pos (C) - Character'Pos ('A') + 10
else 0);
function From_Hex (C1, C2 : in Character) return Character is
(Character'Val (From_Hex (C2) + Interfaces.Shift_Left (From_Hex (C1), 4)));
function To_Hex_Low (C : in Character) return Character is
(Conversion (1 + (Character'Pos (C) mod 16)));
function To_Hex_High (C : in Character) return Character is
(Conversion (1 + (Character'Pos (C) / 16)));
-- ------------------------------
-- Base16 encoder
-- ------------------------------
-- This <b>Encoder</b> translates the (binary) input stream into
-- an ascii hexadecimal stream. The encoding alphabet is: 0123456789ABCDEF.
type Encoder is new Util.Encoders.Transformer with private;
-- Encodes the binary input stream represented by <b>Data</b> into
-- the a base16 (hexadecimal) output stream <b>Into</b>.
--
-- If the transformer does not have enough room to write the result,
-- it must return in <b>Encoded</b> the index of the last encoded
-- position in the <b>Data</b> stream.
--
-- The transformer returns in <b>Last</b> the last valid position
-- in the output stream <b>Into</b>.
--
-- The <b>Encoding_Error</b> exception is raised if the input
-- stream cannot be transformed.
overriding
procedure Transform (E : in out Encoder;
Data : in Ada.Streams.Stream_Element_Array;
Into : out Ada.Streams.Stream_Element_Array;
Last : out Ada.Streams.Stream_Element_Offset;
Encoded : out Ada.Streams.Stream_Element_Offset);
-- ------------------------------
-- Base16 decoder
-- ------------------------------
-- The <b>Decoder</b> decodes an hexadecimal stream into a binary stream.
type Decoder is new Util.Encoders.Transformer with private;
-- Decodes the base16 input stream represented by <b>Data</b> into
-- the binary output stream <b>Into</b>.
--
-- If the transformer does not have enough room to write the result,
-- it must return in <b>Encoded</b> the index of the last encoded
-- position in the <b>Data</b> stream.
--
-- The transformer returns in <b>Last</b> the last valid position
-- in the output stream <b>Into</b>.
--
-- The <b>Encoding_Error</b> exception is raised if the input
-- stream cannot be transformed.
overriding
procedure Transform (E : in out Decoder;
Data : in Ada.Streams.Stream_Element_Array;
Into : out Ada.Streams.Stream_Element_Array;
Last : out Ada.Streams.Stream_Element_Offset;
Encoded : out Ada.Streams.Stream_Element_Offset);
private
type Encoder is new Util.Encoders.Transformer with null record;
type Decoder is new Util.Encoders.Transformer with null record;
generic
type Input_Char is (<>);
type Output_Char is (<>);
type Index is range <>;
type Output_Index is range <>;
type Input is array (Index range <>) of Input_Char;
type Output is array (Output_Index range <>) of Output_Char;
package Encoding is
procedure Encode (From : in Input;
Into : in out Output;
Last : out Output_Index;
Encoded : out Index);
procedure Decode (From : in Input;
Into : in out Output;
Last : out Output_Index;
Encoded : out Index);
end Encoding;
end Util.Encoders.Base16;
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