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/*
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/>.
*/
/**
* @file channels.h
* @brief I/O channels.
* @details This header defines abstract interfaces useful to access generic
* I/O resources in a standardized way.
*
* @addtogroup io_channels
* @{
*/
#ifndef _CHANNELS_H_
#define _CHANNELS_H_
/**
* @brief @p BaseChannel specific methods.
*/
#define _base_channel_methods \
_base_sequental_stream_methods \
/* Channel output check.*/ \
bool_t (*putwouldblock)(void *instance); \
/* Channel input check.*/ \
bool_t (*getwouldblock)(void *instance); \
/* Channel put method with timeout specification.*/ \
msg_t (*put)(void *instance, uint8_t b, systime_t time); \
/* Channel get method with timeout specification.*/ \
msg_t (*get)(void *instance, systime_t time); \
/* Channel write method with timeout specification.*/ \
size_t (*writet)(void *instance, const uint8_t *bp, \
size_t n, systime_t time); \
/* Channel read method with timeout specification.*/ \
size_t (*readt)(void *instance, uint8_t *bp, size_t n, systime_t time);
/**
* @brief @p BaseChannel specific data.
* @note It is empty because @p BaseChannel is only an interface without
* implementation.
*/
#define _base_channel_data \
_base_sequental_stream_data
/**
* @brief @p BaseChannel virtual methods table.
*/
struct BaseChannelVMT { \
_base_channel_methods \
};
/**
* @extends BaseSequentialStream
*
* @brief Base channel class.
* @details This class represents a generic, byte-wide, I/O channel. This class
* introduces generic I/O primitives with timeout specification.
*/
typedef struct {
/** @brief Virtual Methods Table.*/
const struct BaseChannelVMT *vmt;
_base_channel_data
} BaseChannel;
/**
* @brief Channel output check.
* @details This function verifies if a subsequent put/write operation would
* block.
*
* @param[in] ip pointer to a @p BaseChannel or derived class
* @return The output queue status:
* @retval FALSE if the output queue has space and would not block a
* write operation.
* @retval TRUE if the output queue is full and would block a write
* operation.
*/
#define chIOPutWouldBlock(ip) ((ip)->vmt->putwouldblock(ip))
/**
* @brief Channel input check.
* @details This function verifies if a subsequent get/read operation would
* block.
*
* @param[in] ip pointer to a @p BaseChannel or derived class
* @return The input queue status:
* @retval FALSE if the input queue contains data and would not block a
* read operation.
* @retval TRUE if the input queue is empty and would block a read
* operation.
*/
#define chIOGetWouldBlock(ip) ((ip)->vmt->getwouldblock(ip))
/**
* @brief Channel 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 BaseChannel or derived class
* @param[in] b the byte value to be written to the channel
* @return The operation status:
* @retval Q_OK if the operation succeeded.
* @retval Q_RESET if the channel associated queue (if any) was reset.
*/
#define chIOPut(ip, b) ((ip)->vmt->put(ip, b, TIME_INFINITE))
/**
* @brief Channel blocking byte write with timeout.
* @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 BaseChannel or derived class
* @param[in] b the byte value to be written to the channel
* @param[in] time the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return The operation status:
* @retval Q_OK if the operation succeeded.
* @retval Q_TIMEOUT if the specified time expired.
* @retval Q_RESET if the channel associated queue (if any) was reset.
*/
#define chIOPutTimeout(ip, b, time) ((ip)->vmt->put(ip, b, time))
/**
* @brief Channel 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 BaseChannel or derived class
* @return A byte value from the queue or:
* @retval Q_RESET if the channel associated queue (if any) was reset.
*/
#define chIOGet(ip) ((ip)->vmt->get(ip, TIME_INFINITE))
/**
* @brief Channel blocking byte read with timeout.
* @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 BaseChannel or derived class
* @param[in] time the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return A byte value from the queue or:
* @retval Q_TIMEOUT if the specified time expired.
* @retval Q_RESET if the channel associated queue (if any) was reset.
*/
#define chIOGetTimeout(ip, time) ((ip)->vmt->get(ip, time))
/**
* @brief Channel blocking write with timeout.
* @details The function writes data from a buffer 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 BaseChannel or derived class
* @param[out] bp pointer to the data buffer
* @param[in] n the maximum amount of data to be transferred
* @param[in] time the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return The number of bytes transferred.
*/
#define chIOWriteTimeout(ip, bp, n, time) \
((ip)->vmt->write(ip, bp, n, time))
/**
* @brief Channel blocking read with timeout.
* @details The function reads data from a channel into a buffer. If the data
* is not available then the calling thread is suspended.
*
* @param[in] ip pointer to a @p BaseChannel or derived class
* @param[in] bp pointer to the data buffer
* @param[in] n the maximum amount of data to be transferred
* @param[in] time the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return The number of bytes transferred.
*/
#define chIOReadTimeout(ip, bp, n, time) \
((ip)->vmt->read(ip, bp, n, time))
#if CH_USE_EVENTS
/**
* @brief @p BaseAsynchronousChannel specific methods.
*/
#define _base_asynchronous_channel_methods \
_base_channel_methods
/**
* @brief @p BaseAsynchronousChannel specific data.
*/
#define _base_asynchronous_channel_data \
_base_channel_data \
/* Data Available EventSource.*/ \
EventSource ievent; \
/* Data Transmitted EventSource.*/ \
EventSource oevent;
/**
* @brief @p BaseAsynchronousChannel virtual methods table.
*/
struct BaseAsynchronousChannelVMT {
_base_asynchronous_channel_methods
};
/**
* @extends BaseChannel
*
* @brief Base asynchronous channel class.
* @details This class extends @p BaseChannel by adding event sources fields
* for asynchronous I/O for use in an event-driven environment.
*/
typedef struct {
/** @brief Virtual Methods Table.*/
const struct BaseAsynchronousChannelVMT *vmt;
_base_asynchronous_channel_data
} BaseAsynchronousChannel;
/**
* @brief Returns the write event source.
* @details The write event source is broadcasted when the channel is ready
* for write operations. This usually happens when the internal
* output queue becomes empty.
*
* @param[in] ip pointer to a @p BaseAsynchronousChannel or derived
* class
* @return A pointer to an @p EventSource object.
*/
#define chIOGetWriteEventSource(ip) (&((ip)->vmt->oevent))
/**
* @brief Returns the read event source.
* @details The read event source is broadcasted when the channel is ready
* for read operations. This usually happens when the internal
* input queue becomes non-empty.
*
* @param[in] ip pointer to a @p BaseAsynchronousChannel or derived
* class
* @return A pointer to an @p EventSource object.
*/
#define chIOGetReadEventSource(ip) (&((ip)->vmt->ievent))
#endif /* CH_USE_EVENTS */
#endif /* _CHANNELS_H_ */
/** @} */
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