stream_send_ushorts :: Quanser C Functions

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stream_send_ushorts

Writes an array of 16-bit unsigned short integers to the stream buffer.

Description

This function writes an array of 16-bit unsigned short integers to the stream buffer. It attempts to store the short integers in the stream buffer. 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_ushort_array function, this function does not require that the stream send buffer be at least num_elements 16-bit integers in length. Hence, it allows smaller stream buffers to be used.

If the stream has been configured to swap bytes using stream_set_swap_bytes or stream_set_byte_order then this function will swap the order of the bytes within each short integer when they are 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 the total number of short integers sent 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 the number of short integers sent successfully, which will be between 1 and num_elements (unless num_elements is zero). If no short integers could 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_ushorts(t_stream stream, const t_ushort * elements, t_uint num_elements);

Parameters

t_stream stream

A client stream established using stream_connect or stream_accept.

const t_ushort * elements

The array to be sent.

t_uint num_elements

The number of elements in the array to send.

Return value

The number of short integers sent, which may be less than the number requested for non-blocking streams. 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