For the socket based I/O stream implementations (IrDA and bluetooth) the
serial communication specific functions are meaningless. Implementing
them as no-ops allows the dive computer backends the call the I/O stream
functions unconditionally.
This is important for the bluetooth implementation, because bluetooth
enabled dive computers will be able to use both the native bluetooth
communication and the legacy bluetooth serial port emulation.
The dummy IrDA implementation is integrated in the main file. The
appropriate implementation is selected using conditional compilation
based on the features detect by the autotools build system.
The select system call modifies the file descriptor set, and depending
on the underlying implementation also the timeout. Therefore these
parameters should be re-initialized before every call.
The existing code also didn't handle EINTR and EAGAIN correct.
Errors reported by system calls are now converted to the corresponding
libdivecomputer status code. This results in a more descriptive and
meaningfull return value.
The low level serial and IrDA functions are modified to:
- Use the libdivecomputer namespace prefix.
- Return a more detailed status code instead of the zero on success and
negative on error return value. This will allow to return more
fine-grained error codes.
- The read and write functions have an additional output parameter to
return the actual number of bytes transferred. Since these functions
are not atomic, some data might still be transferred successfully if
an error occurs.
The dive computer backends are updated to use the new api.
Unlike the other socket functions, the WSAStartup() function returns the
extended error code directly. A call to the WSAGetLastError() function
is not needed and should not be used.
When the close function returns, all resources should be freed,
regardless of whether an error has occured or not. The error code is
purely informative.
However, in order to return the first error code, which is usually the
most interesting one, the current implementation is unnecessary
complicated. If an error occurs, there is no need to exit immediately.
Simply store the error code unless there is already a previous one, and
then continue.
This is only a cosmetic change, to make the IrDA device address on
Windows consistent with the address Linux. There is no functional
difference because the address is always serialized and deserialized
internally, and applications shouldn't care about the actual number.
Anyway, the difference in endianness is easy to notice because the
Uwatec Smart family of devices use the serial number as the IrDA device
address. On Linux, the address was identical to the serial number, while
on Windows the byte order was reversed.
Apparantly, the windows wingdi.h header file already defines the
ERROR macro. By defining the NOGDI macro before including the
windows.h header file, we can prevent the wingdi.h file from being
included and thus avoid the warning. We don't need that header for
anything anyway.
Because the libusb header file includes the windows.h file
explicitly, it needs the same fix.
The Windows WSAStartup() and WSACleanup() functions are now called
automatically when opening and closing IrDA sockets. This causes no
problems because these functions are reference counted and can be called
multiple times.
In practice nothing changes because the Uwatec Smart backend already
called these functions for every connection.
The public header files are moved to a new subdirectory, to separate
the definition of the public interface from the actual implementation.
Using an identical directory layout as the final installation has the
advantage that the example code can be build outside the project tree
without any modifications to the #include statements.
