stream_send_ubyte_array :: Quanser C Functions

navigation bar

stream_send_ubyte_array

Writes an array of unsigned bytes to the stream buffer.

Description

This function writes an array of unsigned bytes to the stream buffer. It attempts to store the bytes in the stream buffer. It differs from the stream_send_ubytes function in that it treats the entire array as an atomic unit. It either writes all of the array or none of it. If there is enough room available in the stream buffer then it stores the data in the buffer and returns immediately. The data is not written to the actual communication channel until the stream is flushed using stream_flush or there is no more room available in the stream buffer. If an error occurs, then it returns a negative error code. If the connection is closed it is considered an error condition.

Unlike the stream_send_ubytes function, the size of the stream send buffer must be at least as large as the number of bytes being sent.

If stream_listen or stream_connect was called with the non-blocking flag set to false (0), then this function may block attempting to flush the stream buffer. All the data will be consumed and 1 is returned. Some of the data may remain in the stream buffer and not be sent until the next time stream_flush is called or there is no more room available in the stream buffer. If an error occurs then the error code is returned and the stream should be closed.

If stream_listen or stream_connect was called with the non-blocking flag set to true (1), then this function does not block. It returns 1 if the array is sent successfully. If the array could not be sent without blocking, then -QERR_WOULD_BLOCK is returned. If an error occurs then the error code is returned and the stream should be closed.

This function does not support two threads sending or flushing data at the same time. However, data may be sent or the stream flushed by another thread at the same time as data is being received.

The BSD socket API has no equivalent to this function.

Prototype

        
t_int
stream_send_ubyte_array(t_stream stream, const t_ubyte * elements, t_uint num_elements);

Parameters

t_stream stream

A client stream established using stream_connect or stream_accept.

const t_ubyte * elements

The array to be sent.

t_uint num_elements

The number of elements in the array to send.

Return value

Returns 1 on success. If an error occurs then a negative error code is returned.

Error codes

This function does not return any error code.

Requirements

Include Files	Libraries
quanser_stream.h	quanser_communications.lib;quanser_runtime.lib;quanser_common.lib