gnuk/ChibiOS_2.0.8/os/kernel/include/chstreams.h

/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT 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/RT 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/>.

                                      ---

    A special exception to the GPL can be applied should you wish to distribute
    a combined work that includes ChibiOS/RT, without being obliged to provide
    the source code for any proprietary components. See the file exception.txt
    for full details of how and when the exception can be applied.
*/

/**
 * @file    chstreams.h
 * @brief   Data streams.
 * @details This header defines abstract interfaces useful to access generic
 *          data streams in a standardized way.
 *
 * @addtogroup data_streams
 * @details This module define an abstract interface for generic data streams.
 *          Note that no code is present, streams are just abstract interfaces
 *          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 stream interface can be used as base class for high level
 *          object types such as files, sockets, serial ports, pipes etc.
 * @{
 */

#ifndef _CHSTREAMS_H_
#define _CHSTREAMS_H_

/**
 * @brief   BaseSequentialStream specific methods.
 */
#define _base_sequential_stream_methods                                      \
  /* Stream write buffer method.*/                                          \
  size_t (*write)(void *instance, const uint8_t *bp, size_t n);             \
  /* Stream read buffer method.*/                                           \
  size_t (*read)(void *instance, uint8_t *bp, size_t n);

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

/**
 * @brief   @p BaseSequentialStream virtual methods table.
 */
struct BaseSequentialStreamVMT {
  _base_sequential_stream_methods
};

/**
 * @brief   Base stream class.
 * @details This class represents a generic blocking unbuffered sequential
 *          data stream.
 */
typedef struct {
  /** @brief Virtual Methods Table.*/
  const struct BaseSequentialStreamVMT *vmt;
  _base_sequential_stream_data
} BaseSequentialStream;

/**
 * @brief   Sequential Stream write.
 * @details The function writes data from a buffer to a stream.
 *
 * @param[in] ip        pointer to a @p BaseSequentialStream 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 the
 *                      stream reaches a physical end of file and cannot be
 *                      extended.
 */
#define chSequentialStreamWrite(ip, bp, n) ((ip)->vmt->write(ip, bp, n))

/**
 * @brief   Sequential Stream read.
 * @details The function reads data from a stream into a buffer.
 *
 * @param[in] ip        pointer to a @p BaseSequentialStream 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 the
 *                      stream reaches the end of the available data.
 */
#define chSequentialStreamRead(ip, bp, n) ((ip)->vmt->read(ip, bp, n))

#endif /* _CHSTREAMS_H_ */

/** @} */