The main logging function isn't really suitable for generating inline
hexdumps directly from the binary data. There is simply no format string
available for converting array data types with just a single printf
call.
A possible solution would be to require the caller to perform the string
conversion before calling the standard logging function. But that's not
acceptable, because it doesn't play well with the ability to disable the
logging at compile time, requires extra memory and clutters the calling
code unneccessary.
The new function is a compromise which sacrifices flexibility for
simplicity, by using a hardcoded output format with a custom prefix.
It's not a perfect solution, but it works well enough for the intended
purpose.
Pseudo terminals are very convenient for testing purposes, but they are
not fully compatible with real serial (or even usb-serial) hardware.
With the new option, some workarounds can be enabled to hide the
differences and increase compatibility. Although these workarounds
shouldn't cause any problems in production builds, the advise is to
disable this feature.
A few ioctl's are not supported for pseudo terminals. They fail with
EINVAL (Linux) or ENOTTY (Mac OS X). Since these specific error codes
should not occur under normal conditions, they are simply ignored when
pseudo terminal support is enabled.
The TIOCEXCL ioctl (exclusive access) is also problematic. The TIOCEXCL
setting is shared between the master and slave side of the pty. When the
setting is applied on the slave side, it persists for as long as the
master side remains open. The result is that re-opening the slave side
will fail with EBUSY, unless the process has root priviliges. Since this
is very inconvenient, the TIOCEXCL setting is not used when pseudo
terminal support is enabled.
With exclusive access mode, no further open() operations on the terminal
are permitted, except for a process with root priviliges. Non-root
processes will fail with EBUSY. This change will prevent other processes
from accidentally messing up the communication. It also makes the
behaviour similar to Windows, where serial ports are always opened with
exclusive access.
I forgot to update the device and parser initialization functions to
store the context pointer into the objects. As a result, the internal
context pointers were always NULL.
I forgot to update the dummy IrDA backend with the latest changes. The
error, init and cleanup functions have been removed, and the
irda_socket_open function now takes a context pointer.
The status codes in the new EXITCODE macro were not updated to use the
new constants with the namespace prefix. As a result building fails when
compiling with libusb support.
The non-standard vsnprintf implementation provided by MSVC doesn't
matches the C99 function. The wrapper function provides a consistent
interface on top of the native functions.
When the logging is disabling, several compiler warnings regarding
unused variables appear. With the cast to void and sizeof trick the
warnings are silenced without causing any side effects.
With the new option, the library can be compiled with the entire
logging infrastructure disabled. The public api remains unchanged, but
the internal logging functions will have no effect anymore.
In practice the overhead of the logging functions should be quite
small, and disabling the logging at runtime might be more convenient.
Especially because troubleshooting will become much harder without any
logging.
The public api is changed to require a context object for all
operations. Because other library objects store the context pointer
internally, only the constructor functions need an explicit context
object as a parameter.
The new convenience function provides a centralized and threadsafe
function for logging system errors. The previous functions are
deprecated and will be removed after the transition to the new context
based logging.
An application can now register an application defined callback
function, which will perform the actual logging. This provides
additional flexibility compared to logging to stderr with a hardcoded
format. Applications can now easily display the messages in their user
interface, customize the format, etc.
Although the internal logging function is a printf like function, the
arguments are converted into a plain string before being passed to the
callback function. This greatly improves interoperability with
programming languages which don't support C style variadic functions
(e.g. Python, C#, etc).
With the introduction of a context object, library initialization and
shutdown can be performed without requiring any global state. A single
process can use multiple independent contexts without any problems. The
lack of a global state also improves the thread-safety of the library.
At the moment, the new context object is primary used to implement an
improved logging system.
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.
Due to the use of the convenience functions, the device specific header
files are no longer necessary, and can be replaced with the high-level
header files.
A bulk transfer of more than 8K of data takes about one second with the
Cobalt. Because we use a one second timeout combined with a 10K buffer,
such a transfer can easily exceed the timeout. Normally this shouldn't
be a problem because the leftover data is supposed to be received with
the next transfer. However to break out of the loop we check the actual
number of bytes received, and ignore the libusb LIBUSB_ERROR_TIMEOUT
return code.
To fix this problem, the internal buffer is reduced to 8K, and the
timeout is increased to 2 seconds. This should avoid hitting the timeout
and allows to consider LIBUSB_ERROR_TIMEOUT a fatal error.
On Mac OS X (and probably the other BSD's too), the ioctl() syscall
takes an 'unsigned long' integer as the request parameter. On 64bit
systems this is a 64bit type, while on 32bit systems it's a 32bit type.
Some of the request constants are defined as 32 bit negative numbers.
Casting it to a 64bit value will perform a sign extension operation to
preserve the negative value. Because this results in a different request
code when interpreted as an unsigned integer, the ioctl() call fails
with ENOTTY. For example TIOCMBIS is defined as 0x8004746c and becomes
0xffffffff8004746 after the sign extension.
Linux 64bit is unaffected by this problem. None of the request constants
has the sign bit set, and thus the sign extension has no effect. For
example TIOCMBIS is defined as 0x5416.
By using an unsigned integer type, the sign extension can be avoided. We
use the 'unsigned long' type in case one of the request constants
happens to be defined as a 64bit number.
Since automake 1.12, the warnings in the category 'extra-portability'
are now enabled by '-Wall'. Because of this change, linking libtool
archives requires the new AM_PROG_AR macro.
The devinfo and clock event data is now cached internally at the device layer.
This allows the new dc_parser_new() convenience function to retrieve the event
data directly from the device handle, and applications don't have to deal with
the events anymore to create a parser.
With the introduction of the device descriptors, the new dc_device_open()
convenience function can take care of the mapping from a particular model to
the corresponding backend internally, without needing any device specific
knowledge in the application. An application can simply query the list of
supported devices, and the library will automatically do the right thing.
Applications can now enumerate all the supported devices at runtime,
and don't have to maintain their own list anymore. The internal list
does include only those devices that have been confirmed to work at
least once without any major problems.
As the name already indicates, a device descriptor is lightweight
object which describes a single device. Currently, the api supports
getting the device name (vendor and product) and model number. But
this can extended with other features when necessary.
Adding the "dc_" namespace prefix (which is of course an abbreviation
for libdivecomputer) should avoid conflicts with other libraries. For
the time being, only the high-level device and parser layers are
changed.
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.
It looks like the Icon HD erases old dives partially with 0xFF bytes
before overwriting them with new dives. If the head of the oldest dive
has been erased, the length field which is stored in the first 4 bytes
is erased as well, and we can use it to detect the last dive.
For development snapshots, a 'devel' suffix is added to distinguish from
the final release. If necessary, the suffix can also be used for 'alpha'
and 'beta' releases.
For development snapshots, a 'devel' suffix is added to distinguish from
the final release. If necessary, the suffix can also be used for 'alpha'
and 'beta' releases.
The Veo 1.0 has very limited memory and doesn't have a logbook and
profile ringbuffer. Hence downloading dives isn't really supported, but
even this limited amount of data might be useful for someone.
