diff options
Diffstat (limited to 'src/streams.h')
| -rw-r--r-- | src/streams.h | 174 |
1 files changed, 171 insertions, 3 deletions
diff --git a/src/streams.h b/src/streams.h index ed2e985d76..d5565fe61f 100644 --- a/src/streams.h +++ b/src/streams.h @@ -1,5 +1,5 @@ // Copyright (c) 2009-2010 Satoshi Nakamoto -// Copyright (c) 2009-2017 The Bitcoin Core developers +// Copyright (c) 2009-2018 The Bitcoin Core developers // Distributed under the MIT software license, see the accompanying // file COPYING or http://www.opensource.org/licenses/mit-license.php. @@ -61,6 +61,7 @@ public: int GetVersion() const { return nVersion; } int GetType() const { return nType; } + size_t size() const { return stream->size(); } }; template<typename S> @@ -138,6 +139,80 @@ private: size_t nPos; }; +/** Minimal stream for reading from an existing vector by reference + */ +class VectorReader +{ +private: + const int m_type; + const int m_version; + const std::vector<unsigned char>& m_data; + size_t m_pos = 0; + +public: + + /* + * @param[in] type Serialization Type + * @param[in] version Serialization Version (including any flags) + * @param[in] data Referenced byte vector to overwrite/append + * @param[in] pos Starting position. Vector index where reads should start. + */ + VectorReader(int type, int version, const std::vector<unsigned char>& data, size_t pos) + : m_type(type), m_version(version), m_data(data) + { + seek(pos); + } + + /* + * (other params same as above) + * @param[in] args A list of items to deserialize starting at pos. + */ + template <typename... Args> + VectorReader(int type, int version, const std::vector<unsigned char>& data, size_t pos, + Args&&... args) + : VectorReader(type, version, data, pos) + { + ::UnserializeMany(*this, std::forward<Args>(args)...); + } + + template<typename T> + VectorReader& operator>>(T& obj) + { + // Unserialize from this stream + ::Unserialize(*this, obj); + return (*this); + } + + int GetVersion() const { return m_version; } + int GetType() const { return m_type; } + + size_t size() const { return m_data.size() - m_pos; } + bool empty() const { return m_data.size() == m_pos; } + + void read(char* dst, size_t n) + { + if (n == 0) { + return; + } + + // Read from the beginning of the buffer + size_t pos_next = m_pos + n; + if (pos_next > m_data.size()) { + throw std::ios_base::failure("VectorReader::read(): end of data"); + } + memcpy(dst, m_data.data() + m_pos, n); + m_pos = pos_next; + } + + void seek(size_t n) + { + m_pos += n; + if (m_pos > m_data.size()) { + throw std::ios_base::failure("VectorReader::seek(): end of data"); + } + } +}; + /** Double ended buffer combining vector and stream-like interfaces. * * >> and << read and write unformatted data using the above serialization templates. @@ -435,12 +510,105 @@ public: } }; +template <typename IStream> +class BitStreamReader +{ +private: + IStream& m_istream; + + /// Buffered byte read in from the input stream. A new byte is read into the + /// buffer when m_offset reaches 8. + uint8_t m_buffer{0}; + + /// Number of high order bits in m_buffer already returned by previous + /// Read() calls. The next bit to be returned is at this offset from the + /// most significant bit position. + int m_offset{8}; + +public: + explicit BitStreamReader(IStream& istream) : m_istream(istream) {} + + /** Read the specified number of bits from the stream. The data is returned + * in the nbits least significant bits of a 64-bit uint. + */ + uint64_t Read(int nbits) { + if (nbits < 0 || nbits > 64) { + throw std::out_of_range("nbits must be between 0 and 64"); + } + + uint64_t data = 0; + while (nbits > 0) { + if (m_offset == 8) { + m_istream >> m_buffer; + m_offset = 0; + } + int bits = std::min(8 - m_offset, nbits); + data <<= bits; + data |= static_cast<uint8_t>(m_buffer << m_offset) >> (8 - bits); + m_offset += bits; + nbits -= bits; + } + return data; + } +}; +template <typename OStream> +class BitStreamWriter +{ +private: + OStream& m_ostream; + /// Buffered byte waiting to be written to the output stream. The byte is + /// written buffer when m_offset reaches 8 or Flush() is called. + uint8_t m_buffer{0}; + /// Number of high order bits in m_buffer already written by previous + /// Write() calls and not yet flushed to the stream. The next bit to be + /// written to is at this offset from the most significant bit position. + int m_offset{0}; +public: + explicit BitStreamWriter(OStream& ostream) : m_ostream(ostream) {} + ~BitStreamWriter() + { + Flush(); + } + + /** Write the nbits least significant bits of a 64-bit int to the output + * stream. Data is buffered until it completes an octet. + */ + void Write(uint64_t data, int nbits) { + if (nbits < 0 || nbits > 64) { + throw std::out_of_range("nbits must be between 0 and 64"); + } + + while (nbits > 0) { + int bits = std::min(8 - m_offset, nbits); + m_buffer |= (data << (64 - nbits)) >> (64 - 8 + m_offset); + m_offset += bits; + nbits -= bits; + + if (m_offset == 8) { + Flush(); + } + } + } + + /** Flush any unwritten bits to the output stream, padding with 0's to the + * next byte boundary. + */ + void Flush() { + if (m_offset == 0) { + return; + } + + m_ostream << m_buffer; + m_buffer = 0; + m_offset = 0; + } +}; @@ -593,7 +761,7 @@ protected: public: CBufferedFile(FILE *fileIn, uint64_t nBufSize, uint64_t nRewindIn, int nTypeIn, int nVersionIn) : - nType(nTypeIn), nVersion(nVersionIn), nSrcPos(0), nReadPos(0), nReadLimit((uint64_t)(-1)), nRewind(nRewindIn), vchBuf(nBufSize, 0) + nType(nTypeIn), nVersion(nVersionIn), nSrcPos(0), nReadPos(0), nReadLimit(std::numeric_limits<uint64_t>::max()), nRewind(nRewindIn), vchBuf(nBufSize, 0) { src = fileIn; } @@ -678,7 +846,7 @@ public: // prevent reading beyond a certain position // no argument removes the limit - bool SetLimit(uint64_t nPos = (uint64_t)(-1)) { + bool SetLimit(uint64_t nPos = std::numeric_limits<uint64_t>::max()) { if (nPos < nReadPos) return false; nReadLimit = nPos; |