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construct/include/ircd/b64.h

119 lines
2.4 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_B64_H
namespace ircd::b64
{
IRCD_EXCEPTION(ircd::error, error)
IRCD_EXCEPTION(error, invalid_encoding)
using dictionary_element = int;
using dictionary = dictionary_element[64];
extern const dictionary
dict_rfc1421, // [62] = '+', [63] = '/'
dict_rfc3501, // [62] = '+', [63] = ','
dict_rfc4648; // [62] = '-', [63] = '_'
static const auto
&standard { dict_rfc1421 },
&mailbox { dict_rfc3501 },
&urlsafe { dict_rfc4648 };
constexpr size_t decode_size(const size_t) noexcept;
constexpr size_t encode_size(const size_t) noexcept;
constexpr size_t encode_unpadded_size(const size_t) noexcept;
size_t decode_size(const string_view &in) noexcept;
size_t encode_size(const const_buffer &in) noexcept;
size_t encode_unpadded_size(const const_buffer &in) noexcept;
const_buffer decode(const mutable_buffer &out, const string_view &in);
template<const dictionary & = dict_rfc1421>
string_view encode(const mutable_buffer &out, const const_buffer &in) noexcept;
template<const dictionary & = dict_rfc1421>
string_view encode_unpadded(const mutable_buffer &out, const const_buffer &in) noexcept;
}
inline size_t
ircd::b64::encode_unpadded_size(const const_buffer &in)
noexcept
{
return encode_unpadded_size(size(in));
}
inline size_t
ircd::b64::encode_size(const const_buffer &in)
noexcept
{
return encode_size(size(in));
}
inline size_t
ircd::b64::decode_size(const string_view &in)
noexcept
{
const size_t pads
{
endswith_count(in, '=')
};
return decode_size(size(in) - pads);
}
constexpr size_t
ircd::b64::encode_unpadded_size(const size_t in)
noexcept
{
constexpr long double A
{
4.0L / 3.0L
};
const auto e
{
in % 3 != 0
};
return A * in + e;
}
constexpr size_t
ircd::b64::encode_size(const size_t in)
noexcept
{
const auto base
{
encode_unpadded_size(in)
};
const size_t pads
{
(3 - in % 3) % 3
};
return base + pads;
}
constexpr size_t
ircd::b64::decode_size(const size_t in)
noexcept
{
constexpr long double A
{
3.0L / 4.0L
};
return A * in;
}