167 lines
6.7 KiB
C++
167 lines
6.7 KiB
C++
/**
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* Copyright (C) 2015 Trustifier Inc.
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* Copyright (C) 2015 Ahmed Masud
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* Copyright (C) 2015 Topology LP
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* Copyright (C) 2018 Jakob Petsovits
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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* Adapted from https://github.com/ahmed-masud/libbase32,
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* commit 79761b2b79b0545697945efe0987a8d3004512f9.
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* Quite different now.
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*/
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#ifndef CPPCODEC_DETAIL_BASE32
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#define CPPCODEC_DETAIL_BASE32
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#include <stdint.h>
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#include <stdlib.h> // for abort()
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#include "../data/access.hpp"
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#include "../parse_error.hpp"
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#include "config.hpp"
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#include "stream_codec.hpp"
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namespace cppcodec {
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namespace detail {
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template <typename CodecVariant>
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class base32 : public CodecVariant::template codec_impl<base32<CodecVariant>>
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{
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public:
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static inline constexpr uint8_t binary_block_size() { return 5; }
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static inline constexpr uint8_t encoded_block_size() { return 8; }
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static CPPCODEC_ALWAYS_INLINE constexpr uint8_t num_encoded_tail_symbols(uint8_t num_bytes)
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{
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return (num_bytes == 1) ? 2 // 2 symbols, 6 padding characters
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: (num_bytes == 2) ? 4 // 4 symbols, 4 padding characters
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: (num_bytes == 3) ? 5 // 5 symbols, 3 padding characters
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: (num_bytes == 4) ? 7 // 7 symbols, 1 padding characters
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: throw std::domain_error("invalid number of bytes in a tail block");
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}
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template <uint8_t I>
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static CPPCODEC_ALWAYS_INLINE constexpr uint8_t index(
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const uint8_t* b /*binary block*/) noexcept
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{
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static_assert(I >= 0 && I < encoded_block_size(),
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"invalid encoding symbol index in a block");
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return (I == 0) ? ((b[0] >> 3) & 0x1F) // first 5 bits
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: (I == 1) ? (((b[0] << 2) & 0x1C) | ((b[1] >> 6) & 0x3))
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: (I == 2) ? ((b[1] >> 1) & 0x1F)
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: (I == 3) ? (((b[1] << 4) & 0x10) | ((b[2] >> 4) & 0xF))
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: (I == 4) ? (((b[2] << 1) & 0x1E) | ((b[3] >> 7) & 0x1))
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: (I == 5) ? ((b[3] >> 2) & 0x1F)
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: (I == 6) ? (((b[3] << 3) & 0x18) | ((b[4] >> 5) & 0x7))
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: /*I == 7*/ (b[4] & 0x1F); // last 5 bits;
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}
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template <bool B>
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using uint8_if = typename std::enable_if<B, uint8_t>::type;
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template <uint8_t I>
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static CPPCODEC_ALWAYS_INLINE constexpr
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uint8_if<I == 1 || I == 3 || I == 4 || I == 6> index_last(
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const uint8_t* b /*binary block*/) noexcept
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{
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return (I == 1) ? ((b[0] << 2) & 0x1C) // abbreviated 2nd symbol
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: (I == 3) ? ((b[1] << 4) & 0x10) // abbreviated 4th symbol
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: (I == 4) ? ((b[2] << 1) & 0x1E) // abbreviated 5th symbol
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: /*I == 6*/ ((b[3] << 3) & 0x18); // abbreviated 7th symbol
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}
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template <uint8_t I>
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static CPPCODEC_ALWAYS_INLINE
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uint8_if<I != 1 && I != 3 && I != 4 && I != 6> index_last(
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const uint8_t* /*binary block*/)
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{
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throw std::domain_error("invalid last encoding symbol index in a tail");
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}
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template <typename Result, typename ResultState>
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static CPPCODEC_ALWAYS_INLINE void decode_block(
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Result& decoded, ResultState&, const alphabet_index_t* idx);
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template <typename Result, typename ResultState>
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static CPPCODEC_ALWAYS_INLINE void decode_tail(
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Result& decoded, ResultState&, const alphabet_index_t* idx, size_t idx_len);
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};
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//
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// 11111111 10101010 10110011 10111100 10010100
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// => 11111 11110 10101 01011 00111 01111 00100 10100
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//
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template <typename CodecVariant>
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template <typename Result, typename ResultState>
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CPPCODEC_ALWAYS_INLINE void base32<CodecVariant>::decode_block(
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Result& decoded, ResultState& state, const alphabet_index_t* idx)
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{
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put(decoded, state, static_cast<uint8_t>(((idx[0] << 3) & 0xF8) | ((idx[1] >> 2) & 0x7)));
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put(decoded, state, static_cast<uint8_t>(((idx[1] << 6) & 0xC0) | ((idx[2] << 1) & 0x3E) | ((idx[3] >> 4) & 0x1)));
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put(decoded, state, static_cast<uint8_t>(((idx[3] << 4) & 0xF0) | ((idx[4] >> 1) & 0xF)));
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put(decoded, state, static_cast<uint8_t>(((idx[4] << 7) & 0x80) | ((idx[5] << 2) & 0x7C) | ((idx[6] >> 3) & 0x3)));
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put(decoded, state, static_cast<uint8_t>(((idx[6] << 5) & 0xE0) | (idx[7] & 0x1F)));
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}
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template <typename CodecVariant>
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template <typename Result, typename ResultState>
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CPPCODEC_ALWAYS_INLINE void base32<CodecVariant>::decode_tail(
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Result& decoded, ResultState& state, const alphabet_index_t* idx, size_t idx_len)
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{
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if (idx_len == 1) {
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throw invalid_input_length(
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"invalid number of symbols in last base32 block: found 1, expected 2, 4, 5 or 7");
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}
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if (idx_len == 3) {
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throw invalid_input_length(
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"invalid number of symbols in last base32 block: found 3, expected 2, 4, 5 or 7");
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}
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if (idx_len == 6) {
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throw invalid_input_length(
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"invalid number of symbols in last base32 block: found 6, expected 2, 4, 5 or 7");
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}
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// idx_len == 2: decoded size 1
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put(decoded, state, static_cast<uint8_t>(((idx[0] << 3) & 0xF8) | ((idx[1] >> 2) & 0x7)));
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if (idx_len == 2) {
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return;
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}
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// idx_len == 4: decoded size 2
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put(decoded, state, static_cast<uint8_t>(((idx[1] << 6) & 0xC0) | ((idx[2] << 1) & 0x3E) | ((idx[3] >> 4) & 0x1)));
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if (idx_len == 4) {
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return;
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}
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// idx_len == 5: decoded size 3
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put(decoded, state, static_cast<uint8_t>(((idx[3] << 4) & 0xF0) | ((idx[4] >> 1) & 0xF)));
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if (idx_len == 5) {
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return;
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}
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// idx_len == 7: decoded size 4
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put(decoded, state, static_cast<uint8_t>(((idx[4] << 7) & 0x80) | ((idx[5] << 2) & 0x7C) | ((idx[6] >> 3) & 0x3)));
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}
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} // namespace detail
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} // namespace cppcodec
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#endif // CPPCODEC_DETAIL_BASE32
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