CO_STREAM_EOS

int co_stream_eos(co_stream stream);

Header File

co.h

Description

This function checks if a stream is at an end-of-stream condition. This function must be called from within a process run function.

Arguments

The argument for co_stream_eos is as follows :

co_stream stream

A pointer to a stream as passed on the process argument list.

Return Value

Returns an integer value: 0 if no end-of-stream is detected , and 1 if there is an end-of-stream.

Notes

When co_stream_eos returns 1 (true), subsequent calls to co_stream_eos continue to return 1 until the reader closes the stream.

CO_STREAM_OPEN

co_error co_stream_open(co_stream stream,
                        mode_t mode,
                        co_type type);

Header File

co.h

Description

This function opens a stream. It must be called from within a process run function.

Arguments

The arguments for co_stream_open are as follows :

`co_stream stream`	A pointer to a stream as passed on the process argument list.
`mode_t mode`	The stream's read/write mode. Valid modes are `O_RDONLY` and `O_WRONLY` . (There are no bidirectional streams.)
`co_type type`	The stream's data type. The type is normally expressed as a signed or unsigned integer of a specific width using the `INT_TYPE(n)` , `UINT_TYPE(n)` , or `CHAR_TYPE` macros.

Return Value

Possible return values are listed, with the resulting value of co_errno shown in parentheses:

`co_err_none`	Success ( `CO_ENOERROR` ).
`co_err_invalid_arg`	The `stream` argument is `NULL` ( `CO_ENULL_PTR` ) or the `mode` argument is neither `O_RDONLY nor O_WRONLY` ( `CO_EINVALID_MODE` ).
`co_err_already_open`	The stream is already open in this mode ( `CO_EALREADY_OPEN` ).

CO_STREAM_READ

co_error co_stream_read(co_stream stream,
                        void *buffer,
                        size_t buffersize);

Header File

co.h

Description

This function reads a data packet from a previously opened stream. This function must be called from within a process run function.

Arguments

The arguments for co_stream_read are as follows :

`co_stream stream`	A pointer to a stream as passed on the process argument list.
`void *buffer`	A pointer to the destination variable, where read data will be stored. The destination is typically a local variable or array element.
`size_t buffersize`	The size of the destination buffer in bytes. This number must be at least as large as the stream's packet width (in bytes), as specified by `co_stream_create` .

Return Value

Possible return values are listed, with the resulting value of co_errno shown in parentheses:

`co_err_none`	Success ( `CO_ENOERROR` ).
`co_err_eos`	Encountered an end-of-stream token ( `CO_EEOS` ).
`co_err_invalid_arg`	The `stream` argument is `NULL` ( `CO_ENULL_PTR` ) or the `buffersize` argument is smaller than the stream's packet width in bytes ( `CO_EINVALID_STREAM_WIDTH` ).
`co_err_not_open`	The stream is not open for read ( `CO_ENOT_OPEN` ).

Notes

The co_stream_read function must be used only on streams that have been opened with mode O_RDONLY .

The co_stream_read function blocks (waits) if the stream is empty or until the writer closes the stream.

CO_STREAM_READ_NB

co_error co_stream_read_nb(co_stream stream,
                           void *buffer,
                           size_t buffersize);

Header File

co.h

Description

This function reads a data packet from a previously opened stream but does not block if the stream is empty. This function must be called from within a process run function.

Arguments

The arguments for co_stream_read_nb are as follows :

`co_stream stream`	A pointer to a stream as passed on the process argument list.
`void *buffer`	A pointer to the destination variable where read data will be stored. The destination address is typically a local variable or array element.
`size_t buffersize`	The size of the destination buffer, in bytes. This number must be at least as large as the stream's packet width (in bytes), as specified by `co_stream_create` .

Return Value

Possible return values are listed, with the resulting value of co_errno shown in parentheses:

`co_err_none`	Success ( `CO_ENOERROR` ).
`co_err_eos`	Encountered an end-of-stream token ( `CO_EEOS` ).
`co_err_invalid_arg`	The `stream` argument is `NULL` ( `CO_ENULL_PTR` ) or the `buffersize` argument is smaller than the stream's packet width in bytes ( `CO_EINVALID_STREAM_WIDTH` ).
`co_err_not_open`	The stream is not open for reading ( `CO_ENOT_OPEN` ).

Notes

The co_stream_read_nb function must be used only on streams that have been opened with mode O_RDONLY .

The co_stream_read_nb function does not block if the stream is empty. You must therefore check for a co_err_none return value to determine that a data value has been successfully read from the stream.

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Pellerin D., Thibault S.

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