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/**
* Copyright (C) 2015 Topology LP
* Copyright (C) 2013 Adam Rudd (bit calculations)
* Copyright (C) 2018 Jakob Petsovits
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
* Bit calculations adapted from https://github.com/adamvr/arduino-base64,
* commit 999595783185a0afcba156d7276dfeaa9cb5382f.
*/
#ifndef CPPCODEC_DETAIL_BASE64
#define CPPCODEC_DETAIL_BASE64
#include <stdexcept>
#include <stdint.h>
#include "../data/access.hpp"
#include "../parse_error.hpp"
#include "config.hpp"
#include "stream_codec.hpp"
namespace cppcodec {
namespace detail {
template <typename CodecVariant>
class base64 : public CodecVariant::template codec_impl<base64<CodecVariant>>
{
public:
static inline constexpr uint8_t binary_block_size() { return 3; }
static inline constexpr uint8_t encoded_block_size() { return 4; }
static CPPCODEC_ALWAYS_INLINE constexpr uint8_t num_encoded_tail_symbols(uint8_t num_bytes)
{
return (num_bytes == 1) ? 2 // 2 symbols, 2 padding characters
: (num_bytes == 2) ? 3 // 3 symbols, 1 padding character
: throw std::domain_error("invalid number of bytes in a tail block");
}
template <uint8_t I>
static CPPCODEC_ALWAYS_INLINE constexpr uint8_t index(
const uint8_t* b /*binary block*/) noexcept
{
static_assert(I >= 0 && I < encoded_block_size(),
"invalid encoding symbol index in a block");
return (I == 0) ? (b[0] >> 2) // first 6 bits
: (I == 1) ? (((b[0] & 0x3) << 4) | (b[1] >> 4))
: (I == 2) ? (((b[1] & 0xF) << 2) | (b[2] >> 6))
: /*I == 3*/ (b[2] & 0x3F); // last 6 bits
}
template <bool B>
using uint8_if = typename std::enable_if<B, uint8_t>::type;
template <uint8_t I>
static CPPCODEC_ALWAYS_INLINE constexpr uint8_if<I == 1 || I == 2> index_last(
const uint8_t* b /*binary block*/) noexcept
{
return (I == 1) ? ((b[0] & 0x3) << 4) // abbreviated 2nd symbol
: /*I == 2*/ ((b[1] & 0xF) << 2); // abbreviated 3rd symbol
}
template <uint8_t I>
static CPPCODEC_ALWAYS_INLINE uint8_if<I != 1 && I != 2> index_last(
const uint8_t* /*binary block*/)
{
throw std::domain_error("invalid last encoding symbol index in a tail");
}
template <typename Result, typename ResultState>
static CPPCODEC_ALWAYS_INLINE void decode_block(
Result& decoded, ResultState&, const alphabet_index_t* idx);
template <typename Result, typename ResultState>
static CPPCODEC_ALWAYS_INLINE void decode_tail(
Result& decoded, ResultState&, const alphabet_index_t* idx, size_t idx_len);
};
template <typename CodecVariant>
template <typename Result, typename ResultState>
CPPCODEC_ALWAYS_INLINE void base64<CodecVariant>::decode_block(
Result& decoded, ResultState& state, const alphabet_index_t* idx)
{
uint_fast32_t dec = (idx[0] << 18) | (idx[1] << 12) | (idx[2] << 6) | idx[3];
data::put(decoded, state, static_cast<uint8_t>(dec >> 16));
data::put(decoded, state, static_cast<uint8_t>((dec >> 8) & 0xFF));
data::put(decoded, state, static_cast<uint8_t>(dec & 0xFF));
}
template <typename CodecVariant>
template <typename Result, typename ResultState>
CPPCODEC_ALWAYS_INLINE void base64<CodecVariant>::decode_tail(
Result& decoded, ResultState& state, const alphabet_index_t* idx, size_t idx_len)
{
if (idx_len == 1) {
throw invalid_input_length(
"invalid number of symbols in last base64 block: found 1, expected 2 or 3");
}
// idx_len == 2: decoded size 1
data::put(decoded, state, static_cast<uint8_t>((idx[0] << 2) + ((idx[1] & 0x30) >> 4)));
if (idx_len == 2) {
return;
}
// idx_len == 3: decoded size 2
data::put(decoded, state, static_cast<uint8_t>(((idx[1] & 0xF) << 4) + ((idx[2] & 0x3C) >> 2)));
}
} // namespace detail
} // namespace cppcodec
#endif // CPPCODEC_DETAIL_BASE64
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