diff options
Diffstat (limited to 'src/lib/util/ioprocs.h')
-rw-r--r-- | src/lib/util/ioprocs.h | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/src/lib/util/ioprocs.h b/src/lib/util/ioprocs.h index 78c06e71318..0a4e5c384f0 100644 --- a/src/lib/util/ioprocs.h +++ b/src/lib/util/ioprocs.h @@ -27,6 +27,14 @@ class osd_file; namespace util { +/// \defgroup ioprocs Generic I/O interfaces +/// \{ + +/// \brief Interface to an input stream +/// +/// Represents a stream producing a sequence of bytes with no further +/// structure. +/// \sa write_stream read_write_stream random_read class read_stream { public: @@ -34,10 +42,29 @@ public: virtual ~read_stream() = default; + /// \brief Read from the current position in the stream + /// + /// Reads up to the specified number of bytes from the stream into + /// the supplied buffer. May read less than the requested number of + /// bytes if the end of the stream is reached or an error occurs. + /// If the stream supports seeking, reading starts at the current + /// position in the stream, and the current position is incremented + /// by the number of bytes read. + /// \param [out] buffer Destination buffer. Must be large enough to + /// hold the requested number of bytes. + /// \param [in] length Maximum number of bytes to read. + /// \param [out] actual Number of bytes actually read. Will always + /// be less than or equal to the requested length. + /// \return An error condition if reading stopped due to an error. virtual std::error_condition read(void *buffer, std::size_t length, std::size_t &actual) noexcept = 0; }; +/// \brief Interface to an output stream +/// +/// Represents a stream that accepts a sequence of bytes with no further +/// structure. +/// \sa read_stream read_write_stream random_write class write_stream { public: @@ -45,12 +72,43 @@ public: virtual ~write_stream() = default; + /// \brief Finish writing data + /// + /// Performs any tasks necessary to finish writing data to the + /// stream and guarantee that the written data can be read in its + /// entirety. Further writes may not be possible. + /// \return An error condition if the operation fails. virtual std::error_condition finalize() noexcept = 0; + + /// \brief Flush application-side caches + /// + /// Flushes any caches to the underlying stream. Success does not + /// guarantee that data has reached persistent storage. + /// \return An error condition if flushing caches fails. virtual std::error_condition flush() noexcept = 0; + + /// \brief Write at the current position in the stream + /// + /// Writes up to the specified number of bytes from the supplied + /// buffer to the stream. May write less than the requested number + /// of bytes if an error occurs. If the stream supports seeking, + /// writing starts at the current position in the stream, and the + /// current position is incremented by the number of bytes written. + /// \param [in] buffer Buffer containing the data to write. Must + /// contain at least the specified number of bytes. + /// \param [in] length Number of bytes to write. + /// \param [out] actual Number of bytes actually written. Will + /// always be less than or equal to the requested length. + /// \return An error condition if writing stopped due to an error. virtual std::error_condition write(void const *buffer, std::size_t length, std::size_t &actual) noexcept = 0; }; +/// \brief Interface to an I/O stream +/// +/// Represents an object that acts as both a source of and sink for byte +/// sequences. +/// \sa read_stream write_stream random_read_write class read_write_stream : public virtual read_stream, public virtual write_stream { public: @@ -58,41 +116,121 @@ public: }; +/// \brief Interface to a byte sequence that supports seeking +/// +/// Provides an interface for controlling the position within a byte +/// sequence that supports seeking. +/// \sa random_read random_write random_read_write class random_access { public: virtual ~random_access() = default; + /// \brief Set the position in the stream + /// + /// Sets the position for the next read or write operation. It may + /// be possible to set the position beyond the end of the stream. + /// \param [in] offset The offset in bytes, relative to the position + /// specified by the whence parameter. + /// \param [in] whence One of SEEK_SET, SEEK_CUR or SEEK_END, to + /// interpret the offset parameter relative to the beginning of + /// the stream, the current position in the stream, or the end of + /// the stream, respectively. + /// \return An error condition of the operation failed. virtual std::error_condition seek(std::int64_t offset, int whence) noexcept = 0; + + /// \brief Get the current position in the stream + /// + /// Gets the position in the stream for the next read or write + /// operation. The position may be beyond the end of the stream. + /// \param [out] result The position in bytes relative to the + /// beginning of the stream. Not valid if the operation fails. + /// \return An error condition if the operation failed. virtual std::error_condition tell(std::uint64_t &result) noexcept = 0; + + /// \brief Get the length of the stream + /// + /// Gets the current length of the stream. + /// \param [out] result The lenght of the stream in bytes. Not + /// valid if the operation fails. + /// \return An error condtion if the operation failed. virtual std::error_condition length(std::uint64_t &result) noexcept = 0; }; +/// \brief Interface to a random-access byte input sequence +/// +/// Provides an interface for reading from aritrary positions within a +/// byte sequence. No further structure is provided. +/// \sa read_stream random_write random_read_write class random_read : public virtual read_stream, public virtual random_access { public: using ptr = std::unique_ptr<random_read>; + /// \brief Read from specified position + /// + /// Reads up to the specified number of bytes into the supplied + /// buffer. If seeking is supported, reading starts at the + /// specified position and the current position is unaffected. May + /// read less than the requested number of bytes if the end of the + /// stream is encountered or an error occurs. + /// \param [in] offset The position to start reading from, specified + /// as a number of bytes from the beginning of the stream. + /// \param [out] buffer Destination buffer. Must be large enough to + /// hold the requested number of bytes. + /// \param [in] length Maximum number of bytes to read. + /// \param [out] actual Number of bytes actually read. Will always + /// be less than or equal to the requested length. + /// \return An error condition if seeking failed or reading stopped + /// due to an error. virtual std::error_condition read_at(std::uint64_t offset, void *buffer, std::size_t length, std::size_t &actual) noexcept = 0; }; +/// \brief Interface to a random-access byte output sequence +/// +/// Provides an interface for writing to arbitrary positions within a +/// byte sequence. No further structure is provided. +/// \sa write_stream random_read random_read_write class random_write : public virtual write_stream, public virtual random_access { public: using ptr = std::unique_ptr<random_write>; + /// \brief Write at specified position + /// + /// Writes up to the specified number of bytes from the supplied + /// buffer. If seeking is supported, writing starts at the + /// specified position and the current position is unaffected. May + /// write less than the requested number of bytes if an error + /// occurs. + /// \param [in] offset The position to start writing at, specified + /// as a number of bytes from the beginning of the stream. + /// \param [in] buffer Buffer containing the data to write. Must + /// contain at least the specified number of bytes. + /// \param [in] length Number of bytes to write. + /// \param [out] actual Number of bytes actually written. Will + /// always be less than or equal to the requested length. + /// \return An error condition if seeking failed or writing stopped + /// due to an error. virtual std::error_condition write_at(std::uint64_t offset, void const *buffer, std::size_t length, std::size_t &actual) noexcept = 0; }; +/// \brief Interface to a random-access read/write byte sequence +/// +/// Provides an interface for reading from and writing to arbitrary +/// positions within a byte sequence. No further structure is provided. +/// \sa random_read random_write read_write_stream class random_read_write : public read_write_stream, public virtual random_read, public virtual random_write { public: using ptr = std::unique_ptr<random_read_write>; }; +/// \} + random_read::ptr ram_read(void const *data, std::size_t size) noexcept; random_read::ptr ram_read(void const *data, std::size_t size, std::uint8_t filler) noexcept; |