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/****************************************************************************
*
* Copyright (C) 2012 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file hx_stream.h
*
* A simple serial line framing protocol based on HDLC
* with 32-bit CRC protection.
*/
#ifndef _SYSTEMLIB_HX_STREAM_H
#define _SYSTEMLIB_HX_STREAM_H
#include <sys/types.h>
#include "perf_counter.h"
struct hx_stream;
typedef struct hx_stream *hx_stream_t;
#define HX_STREAM_MAX_FRAME 64
typedef void (* hx_stream_rx_callback)(void *arg, const void *data, size_t length);
__BEGIN_DECLS
/**
* Allocate a new hx_stream object.
*
* @param fd The file handle over which the protocol will
* communicate, or -1 if the protocol will use
* hx_stream_start/hx_stream_send_next.
* @param callback Called when a frame is received.
* @param callback_arg Passed to the callback.
* @return A handle to the stream, or NULL if memory could
* not be allocated.
*/
__EXPORT extern hx_stream_t hx_stream_init(int fd,
hx_stream_rx_callback callback,
void *arg);
/**
* Free a hx_stream object.
*
* @param stream A handle returned from hx_stream_init.
*/
__EXPORT extern void hx_stream_free(hx_stream_t stream);
/**
* Set performance counters for the stream.
*
* Any counter may be set to NULL to disable counting that datum.
*
* @param stream A handle returned from hx_stream_init.
* @param tx_frames Counter for transmitted frames.
* @param rx_frames Counter for received frames.
* @param rx_errors Counter for short and corrupt received frames.
*/
__EXPORT extern void hx_stream_set_counters(hx_stream_t stream,
perf_counter_t tx_frames,
perf_counter_t rx_frames,
perf_counter_t rx_errors);
/**
* Reset a stream.
*
* Forces the local stream state to idle.
*
* @param stream A handle returned from hx_stream_init.
*/
__EXPORT extern void hx_stream_reset(hx_stream_t stream);
/**
* Prepare to send a frame.
*
* Use this in conjunction with hx_stream_send_next to
* set the frame to be transmitted.
*
* Use hx_stream_send() to write to the stream fd directly.
*
* @param stream A handle returned from hx_stream_init.
* @param data Pointer to the data to send.
* @param count The number of bytes to send.
* @return Zero on success, -errno on error.
*/
__EXPORT extern int hx_stream_start(hx_stream_t stream,
const void *data,
size_t count);
/**
* Get the next byte to send for a stream.
*
* This requires that the stream be prepared for sending by
* calling hx_stream_start first.
*
* @param stream A handle returned from hx_stream_init.
* @return The byte to send, or -1 if there is
* nothing left to send.
*/
__EXPORT extern int hx_stream_send_next(hx_stream_t stream);
/**
* Send a frame.
*
* This function will block until all frame bytes are sent if
* the descriptor passed to hx_stream_init is marked blocking,
* otherwise it will return -1 (but may transmit a
* runt frame at the same time).
*
* @todo Handling of non-blocking streams needs to be better.
*
* @param stream A handle returned from hx_stream_init.
* @param data Pointer to the data to send.
* @param count The number of bytes to send.
* @return Zero on success, -errno on error.
*/
__EXPORT extern int hx_stream_send(hx_stream_t stream,
const void *data,
size_t count);
/**
* Handle a byte from the stream.
*
* @param stream A handle returned from hx_stream_init.
* @param c The character to process.
*/
__EXPORT extern void hx_stream_rx(hx_stream_t stream,
uint8_t c);
__END_DECLS
#endif
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