ChibiOS/os/hal/include/hal_files.h

/*
    ChibiOS - Copyright (C) 2006..2015 Giovanni Di Sirio.

    This file is part of ChibiOS.

    ChibiOS is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file    hal_files.h
 * @brief   Data files.
 * @details This header defines abstract interfaces useful to access generic
 *          data files in a standardized way.
 *
 * @addtogroup HAL_FILES
 * @details This module define an abstract interface for generic data files by
 *          extending the @p BaseSequentialStream interface. Note that no code
 *          is present, data files are just abstract interface-like structures,
 *          you should look at the systems as to a set of abstract C++ classes
 *          (even if written in C). This system has the advantage to make the
 *          access to streams independent from the implementation logic.<br>
 *          The data files interface can be used as base class for high level
 *          object types such as an API for a File System implementation.
 * @{
 */

#ifndef _HAL_FILES_H_
#define _HAL_FILES_H_

/**
 * @name    Files return codes
 * @{
 */
/**
 * @brief   No error return code.
 */
#define FILE_OK         STM_OK

/**
 * @brief   Error code from the file stream methods.
 */
#define FILE_ERROR      STM_TIMEOUT

/**
 * @brief   End-of-file condition for file get/put methods.
 */
#define FILE_EOF        STM_RESET
/** @} */

/**
 * @brief   File offset type.
 */
typedef uint32_t fileoffset_t;

/**
 * @brief   FileStream specific methods.
 */
#define _file_stream_methods                                                \
  _base_sequential_stream_methods                                           \
  /* File close method.*/                                                   \
  msg_t (*close)(void *instance);                                           \
  /* Get last error code method.*/                                          \
  msg_t (*geterror)(void *instance);                                        \
  /* File get size method.*/                                                \
  msg_t (*getsize)(void *instance);                                         \
  /* File get current position method.*/                                    \
  msg_t (*getposition)(void *instance);                                     \
  /* File seek method.*/                                                    \
  msg_t (*lseek)(void *instance, fileoffset_t offset);

/**
 * @brief   @p FileStream specific data.
 * @note    It is empty because @p FileStream is only an interface
 *          without implementation.
 */
#define _file_stream_data                                                   \
  _base_sequential_stream_data

/**
 * @extends BaseSequentialStreamVMT
 *
 * @brief   @p FileStream virtual methods table.
 */
struct FileStreamVMT {
  _file_stream_methods
};

/**
 * @extends BaseSequentialStream
 *
 * @brief   Base file stream class.
 * @details This class represents a generic file data stream.
 */
typedef struct {
  /** @brief Virtual Methods Table.*/
  const struct FileStreamVMT *vmt;
  _file_stream_data
} FileStream;

/**
 * @name    Macro Functions (FileStream)
 * @{
 */
/**
 * @brief   File stream write.
 * @details The function writes data from a buffer to a file stream.
 *
 * @param[in] ip        pointer to a @p FileStream or derived class
 * @param[in] bp        pointer to the data buffer
 * @param[in] n         the maximum amount of data to be transferred
 * @return              The number of bytes transferred. The return value can
 *                      be less than the specified number of bytes if an
 *                      end-of-file condition has been met.
 * @retval FILE_ERROR   operation failed.
 *
 * @api
 */
#define fileStreamWrite(ip, bp, n) streamWrite(ip, bp, n)

/**
 * @brief   File stream read.
 * @details The function reads data from a file stream into a buffer.
 *
 * @param[in] ip        pointer to a @p FileStream or derived class
 * @param[out] bp       pointer to the data buffer
 * @param[in] n         the maximum amount of data to be transferred
 * @return              The number of bytes transferred. The return value can
 *                      be less than the specified number of bytes if an
 *                      end-of-file condition has been met.
 * @retval FILE_ERROR   operation failed.
 *
 * @api
 */
#define fileStreamRead(ip, bp, n) streamRead(ip, bp, n)

/**
 * @brief   File stream blocking byte write.
 * @details This function writes a byte value to a channel. If the channel
 *          is not ready to accept data then the calling thread is suspended.
 *
 * @param[in] ip        pointer to a @p FileStream or derived class
 * @param[in] b         the byte value to be written to the channel
 *
 * @return              The operation status.
 * @retval FILE_OK      if the operation succeeded.
 * @retval FILE_ERROR   operation failed.
 * @retval FILE_EOF     if an end-of-file condition has been met.
 *
 * @api
 */
#define fileStreamPut(ip, b) streamPut(ip, b)

/**
 * @brief   File stream blocking byte read.
 * @details This function reads a byte value from a channel. If the data
 *          is not available then the calling thread is suspended.
 *
 * @param[in] ip        pointer to a @p FileStream or derived class
 *
 * @return              A byte value from the queue.
 * @retval FILE_ERROR   operation failed.
 * @retval FILE_EOF     if an end-of-file condition has been met.
 *
 * @api
 */
#define fileStreamGet(ip) streamGet(ip)

/**
 * @brief   File Stream close.
 * @details The function closes a file stream.
 *
 * @param[in] ip        pointer to a @p FileStream or derived class
 * @return              The operation status.
 * @retval FILE_OK      no error.
 * @retval FILE_ERROR   operation failed.
 *
 * @api
 */
#define fileStreamClose(ip) ((ip)->vmt->close(ip))

/**
 * @brief   Returns an implementation dependent error code.
 * @pre     The previously called function must have returned @p FILE_ERROR.
 *
 * @param[in] ip        pointer to a @p FileStream or derived class
 * @return              Implementation dependent error code.
 *
 * @api
 */
#define fileStreamGetError(ip) ((ip)->vmt->geterror(ip))

/**
 * @brief   Returns the current file size.
 *
 * @param[in] ip        pointer to a @p FileStream or derived class
 * @return              The file size.
 * @retval FILE_ERROR   operation failed.
 *
 * @api
 */
#define fileStreamGetSize(ip) ((ip)->vmt->getsize(ip))

/**
 * @brief   Returns the current file pointer position.
 *
 * @param[in] ip        pointer to a @p FileStream or derived class
 * @return              The current position inside the file.
 * @retval FILE_ERROR   operation failed.
 *
 * @api
 */
#define fileStreamGetPosition(ip) ((ip)->vmt->getposition(ip))

/**
 * @brief   Moves the file current pointer to an absolute position.
 *
 * @param[in] ip        pointer to a @p FileStream or derived class
 * @param[in] offset    new absolute position
 * @return              The operation status.
 * @retval FILE_OK      no error.
 * @retval FILE_ERROR   operation failed.
 *
 * @api
 */
#define fileStreamSeek(ip, offset) ((ip)->vmt->lseek(ip, offset))
/** @} */

#endif /* _HAL_FILES_H_ */

/** @} */