Hi David, On 8 June 2018 at 04:27, David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote: > On Wed, Jun 06, 2018 at 03:37:02PM -0600, Simon Glass wrote: >> Export all of these through Python. >> >> Signed-off-by: Simon Glass <sjg@xxxxxxxxxxxx> >> --- >> >> Changes in v2: >> - Drop use of check_err() since these functions cannot fail >> - Update existing header functions to also drop check_err() >> >> pylibfdt/libfdt.i | 71 +++++++++++++++++++++++++++++++++++++++-- >> tests/pylibfdt_tests.py | 8 +++++ >> 2 files changed, 76 insertions(+), 3 deletions(-) >> >> diff --git a/pylibfdt/libfdt.i b/pylibfdt/libfdt.i >> index 94c3d00..f33e2ab 100644 >> --- a/pylibfdt/libfdt.i >> +++ b/pylibfdt/libfdt.i >> @@ -252,21 +252,86 @@ class Fdt: >> """ >> return check_err(fdt_next_subnode(self._fdt, nodeoffset), quiet) >> >> + def magic(self): >> + """Return the magic word from the header >> + >> + Returns: >> + Magic word >> + """ >> + # Use a mask to ensure that this does not return a -ve number >> + return fdt_magic(self._fdt) & 0xffffffff > > You still have the mask here for no clear reason. Python's numbers are a little strange. If the top bit of a 32-bit number is set, this means it is a negative number in two-complement arithmetic, as you know. Python will then use a negative value instead of positive. To force it to regard the number as unsigned, we must mask it. This is how I have learned to do it in Python, but maybe there is a better way? To see the impact, try removing the mask. You will see that magic() will return a -ve number, rather than unsigned. Regards, Simon -- To unsubscribe from this list: send the line "unsubscribe devicetree-compiler" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
