Jan Roelens schrieb: > Dear python experts, > > How can I change the alignment of types in the ctypes package? I have > a library that was built with gcc using the -malign-double option. I > also have python code that can create ctypes wrapper code from the > include files for that library. The problem is that structs that > contain fields of type double are not correctly wrapped half of the > time. This is because ctypes assumes an alignment of 4 (on a 32-bit > platform) for the double type, while the library I'm wrapping uses an > alignment of 8 for these doubles.
To force an alignment that is smaller than the native alignment, you can use the _pack_ attribute in your Structure definitions. http://docs.python.org/library/ctypes.html?highlight=_pack_#ctypes.Structure._pack_ To force an alignment that is larger than the native alignment, you must use padding. > Is there a way to change the alignment of a ctypes type without > recompiling the whole ctypes package? If I can't change it, is there a > way to define my own type based on c_double but with a different > alignment? No. Thomas -- http://mail.python.org/mailman/listinfo/python-list
