[Numpy-discussion] UInt64 is not supported on 64-bit architecture?

Francesc Alted falted at openlc.org
Tue Mar 18 10:53:32 CST 2003


A Dimarts 18 Març 2003 18:24, Todd Miller va escriure:
> That's great to hear!  Incidentally,  you should probably also set LP64
> to 1.  That asserts that a Python integer (a C long) is 64-bits and
> makes the default array integer type Int64 rather than Int32.  I don't
> know anything about SGI,  but you can determine if LP64 is appropriate
> by looking at sys.maxint:  2-billionish is 32-bit,  9-gazillionish is
> 64-bit.

Well, to say the truth, I've already tested that, but it gave me some weird
errors with the Numeric compatibility tests included in PyTables. In
particular, it seems to make a difference between the "l" (long) and "i"
(int) typecodes, that make the tests to fail (maybe I should investigate
this more, but I'm short of time lately).

Besides, my python on IRIX seems to not support well the 64-bits integers:

nut 432$ python
Python 2.2.2 (#2, Nov 19 2002, 18:46:18)
[GCC 2.95.2 19991024 (release)] on irix646
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.maxint
2147483647

which is the same as an 32-bit machine.

I think this is because I've compiled python with gcc 2.95.2 and it doesn't
support 64-bit integers. From the gcc man pages:

              MIPS Options
              -mcpu=cpu type -mips2 -mips3 -mint64 -mlong64
              -mlonglong128 -mmips-as -mgas -mrnames -mno-rnames
              -mgpopt -mno-gpopt -mstats -mno-stats -mmemcpy
              -mno-memcpy -mno-mips-tfile -mmips-tfile
              -msoft-float -mhard-float -mabicalls -mno-abicalls
              -mhalf-pic -mno-half-pic -G num -nocpp

but later you can read:

       -mint64

       -mlong64

       -mlonglong128
              These options don't work at present.


So it seems like if could be dangerous to force the default integer types to
Int64.

But anyway, this is most probably a limitation of GNU gcc than a flaw on
IRIX. I could test with the MIPSpro C compiler, but I've no time rigth now.

Regards,

-- 
Francesc Alted




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