On 03-Oct-16 16:35, Michael Felt wrote:
I'd alias the type instead of defining a struct, e.g. `time_t =
c_long`. This preserves automatic conversion of the simple type.
The reason for the not using alias is because a) I was trying to be
more inline with the text of the include file.
I will have to check the sizeof c_long (i.e., sizeof(long) in both 32
and 64-bit modes
Also, sys.maxsize is based on the platform's size_t type. That's
generally the same size as a pointer, but C doesn't require this.
Instead use sizeof(c_void_p), which will be 8 on a 64-bit platform and
4 on a 32-bit platform.
I had checked this before - I shall have to try a 32-bit python to see
what _ctypes is doing with c_long on AIX - is it 4, or is it 8.
michael@x071:[/data/prj/python/cloud-init/aix-cloud-init-0.7.8.1/new]cat
xxx.c
#include <libperfstat.h>
time_t
lbolt()
{
perfstat_cpu_total_t cpu_totals;
void *p1, *p2;
printf("int_size:%d\n", sizeof(int));
printf("long_size:%d\n", sizeof(long));
printf("timet_size:%d\n", sizeof(time_t));
printf("void_ptr_size:%d\n", sizeof(void *));
printf("lbolt_size:%d\n", sizeof(cpu_totals.lbolt));
p1 = &cpu_totals;
p2 = &cpu_totals.lbolt;
printf("lbolt offset:%d\n", p2 - p1);
}
main()
{
lbolt();
}
michael@x071:[/data/prj/python/cloud-init/aix-cloud-init-0.7.8.1/new]cc
-q32 >
int_size:4
long_size:4
timet_size:4
void_ptr_size:4
lbolt_size:4
lbolt offset:192
michael@x071:[/data/prj/python/cloud-init/aix-cloud-init-0.7.8.1/new]cc
-q64 >
int_size:4
long_size:8
timet_size:8
void_ptr_size:8
lbolt_size:8
lbolt offset:192
I think 4 and 8 because of problems I have with this block when not in
the right "mode", i.e. SIZEOF_LONG changes
#if LONG_BIT != 8 * SIZEOF_LONG
/* 04-Oct-2000 LONG_BIT is apparently (mis)defined as 64 on some recent
* 32-bit platforms using gcc. We try to catch that here at compile-time
* rather than waiting for integer multiplication to trigger bogus
* overflows.
*/
#error "LONG_BIT definition appears wrong for platform (bad gcc/glibc
config?)."
#endif
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