307 lines
9.3 KiB
C++
307 lines
9.3 KiB
C++
/*
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SPDX-License-Identifier: GPL-3.0-or-later
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Copyright © 1991-2022 Amebis
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Copyright © 2016 GÉANT
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*/
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///
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/// \defgroup WinStdBase64 Base64 conversion
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/// Provides Base64 conversion for WinStd classes
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///
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#include "Common.h"
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#include <string>
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#include <vector>
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namespace winstd
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{
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class base64_enc;
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class base64_dec;
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}
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#pragma once
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namespace winstd
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{
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/// \addtogroup WinStdBase64
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/// @{
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///
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/// Base64 encoding session
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///
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class base64_enc
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{
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public:
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///
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/// Constructs blank encoding session
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///
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inline base64_enc() noexcept : num(0)
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{
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buf[0] = 0;
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buf[1] = 0;
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buf[2] = 0;
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}
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///
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/// Encodes one block of information, and _appends_ it to the output
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///
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/// \param[out] out Output
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/// \param[in ] data Data to encode
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/// \param[in ] size Length of `data` in bytes
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/// \param[in ] is_last Is this the last block of data?
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///
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template<class _Elem, class _Traits, class _Ax>
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inline void encode(_Inout_ std::basic_string<_Elem, _Traits, _Ax> &out, _In_bytecount_(size) const void *data, _In_ size_t size, _In_opt_ bool is_last = true)
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{
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assert(data || !size);
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// Preallocate output
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out.reserve(out.size() + enc_size(size));
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// Convert data character by character.
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for (size_t i = 0;; i++) {
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if (num >= 3) {
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encode(out);
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num = 0;
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}
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if (i >= size)
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break;
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buf[num++] = reinterpret_cast<const unsigned char*>(data)[i];
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}
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// If this is the last block, flush the buffer.
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if (is_last && num) {
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encode(out, num);
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num = 0;
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}
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}
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///
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/// Resets encoding session
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///
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inline void clear() noexcept
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{
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num = 0;
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}
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///
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/// Returns maximum encoded size
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///
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/// \param size Number of bytes to encode
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///
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/// \returns Maximum number of bytes for the encoded data of `size` length
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///
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inline size_t enc_size(size_t size) const noexcept
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{
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return ((num + size + 2)/3)*4;
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}
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protected:
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///
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/// Encodes one complete internal buffer of data
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///
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template<class _Elem, class _Traits, class _Ax>
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inline void encode(_Inout_ std::basic_string<_Elem, _Traits, _Ax> &out)
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{
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out += lookup[ buf[0] >> 2 ];
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out += lookup[((buf[0] << 4) | (buf[1] >> 4)) & 0x3f];
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out += lookup[((buf[1] << 2) | (buf[2] >> 6)) & 0x3f];
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out += lookup[ buf[2] & 0x3f];
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}
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///
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/// Encodes partial internal buffer of data
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///
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template<class _Elem, class _Traits, class _Ax>
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inline void encode(_Inout_ std::basic_string<_Elem, _Traits, _Ax> &out, _In_ size_t size)
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{
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if (size > 0) {
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out += lookup[buf[0] >> 2];
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if (size > 1) {
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out += lookup[((buf[0] << 4) | (buf[1] >> 4)) & 0x3f];
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if (size > 2) {
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out += lookup[((buf[1] << 2) | (buf[2] >> 6)) & 0x3f];
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out += lookup[buf[2] & 0x3f];
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} else {
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out += lookup[(buf[1] << 2) & 0x3f];
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out += '=';
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}
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} else {
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out += lookup[(buf[0] << 4) & 0x3f];
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out += '=';
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out += '=';
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}
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} else {
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out += '=';
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out += '=';
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out += '=';
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out += '=';
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}
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}
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protected:
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unsigned char buf[3]; ///< Internal buffer
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size_t num; ///< Number of bytes used in `buf`
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/// \cond internal
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static const char lookup[64];
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/// \endcond
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};
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/// \cond internal
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const char base64_enc::lookup[64] = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
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};
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/// \endcond
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///
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/// Base64 decoding session
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///
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class base64_dec
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{
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public:
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///
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/// Constructs blank decoding session
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///
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inline base64_dec() noexcept : num(0)
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{
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buf[0] = 0;
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buf[1] = 0;
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buf[2] = 0;
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buf[3] = 0;
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}
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///
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/// Decodes one block of information, and _appends_ it to the output
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///
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/// \param[out] out Output
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/// \param[in ] is_last Was this the last block of data?
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/// \param[in ] data Data to decode
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/// \param[in ] size Length of `data` in bytes
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///
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template<class _Ty, class _Ax, class _Tchr>
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inline void decode(_Inout_ std::vector<_Ty, _Ax> &out, _Out_ bool &is_last, _In_z_count_(size) const _Tchr *data, _In_ size_t size)
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{
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is_last = false;
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// Trim data size to first terminator.
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for (size_t k = 0; k < size; k++)
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if (!data[k]) { size = k; break; }
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// Preallocate output
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out.reserve(out.size() + dec_size(size));
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for (size_t i = 0;; i++) {
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if (num >= 4) {
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// Buffer full; decode it.
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size_t nibbles = decode(out);
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num = 0;
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if (nibbles < 3) {
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is_last = true;
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break;
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}
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}
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if (i >= size)
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break;
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int x = data[i];
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if ((buf[num] = x < _countof(lookup) ? lookup[x] : 255) != 255)
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num++;
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}
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}
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///
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/// Resets decoding session
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///
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inline void clear() noexcept
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{
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num = 0;
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}
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///
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/// Returns maximum decoded size
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///
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/// \param size Number of bytes to decode
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///
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/// \returns Maximum number of bytes for the decoded data of `size` length
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///
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inline size_t dec_size(size_t size) const noexcept
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{
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return ((num + size + 3)/4)*3;
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}
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protected:
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///
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/// Decodes one complete internal buffer of data
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///
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template<class _Ty, class _Ax>
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inline size_t decode(_Inout_ std::vector<_Ty, _Ax> &out)
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{
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out.push_back((_Ty)(((buf[0] << 2) | (buf[1] >> 4)) & 0xff));
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if (buf[2] < 64) {
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out.push_back((_Ty)(((buf[1] << 4) | (buf[2] >> 2)) & 0xff));
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if (buf[3] < 64) {
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out.push_back((_Ty)(((buf[2] << 6) | buf[3]) & 0xff));
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return 3;
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} else
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return 2;
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} else
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return 1;
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}
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protected:
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unsigned char buf[4]; ///< Internal buffer
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size_t num; ///< Number of bytes used in `buf`
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/// \cond internal
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static const unsigned char lookup[256];
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/// \endcond
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};
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/// \cond internal
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const unsigned char base64_dec::lookup[256] = {
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/* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
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/* 0 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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/* 1 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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/* 2 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63,
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/* 3 */ 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255, 64, 255, 255,
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/* 4 */ 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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/* 5 */ 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255,
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/* 6 */ 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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/* 7 */ 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 255, 255, 255, 255, 255,
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/* 8 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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/* 9 */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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/* A */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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/* B */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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/* C */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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/* D */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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/* E */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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/* F */ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255
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};
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/// \endcond
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/// @}
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}
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