Problems with libdivecomputer under OSX

[Pascal Manchon]

Actually, it looks like it comes from a cast from the defined TIOCMBIS/TIOCMBIC to signed int then back to unsigned long. The compiler believes we ask him to keep the integer value and not the bytes :

  printf("%ld %ld\n", sizeof(int), sizeof(unsigned long));
>>>> 4 8

  printf("%lx %lx\n", TIOCMBIS, TIOCMBIC);
>>>> 8004746c 8004746b

  unsigned long a = TIOCMBIS;
  unsigned long b = TIOCMBIC;
  printf("%lx %lx\n", a, b);
>>>> 8004746c 8004746b

  int c = TIOCMBIS;
  int d = TIOCMBIC;
  printf("%x %x\n", c, d);
  printf("%lx %lx\n", (unsigned long)c, (unsigned long)d);
>>>> 8004746c 8004746b
>>>> ffffffff8004746c ffffffff8004746b

  unsigned int e = TIOCMBIS;
  unsigned int f = TIOCMBIC;
  printf("%x %x\n", e, f);
  printf("%lx %lx\n", (unsigned long)e, (unsigned long)f);
>>>> 8004746c 8004746b
>>>> 8004746c 8004746b


Linux has much lower values (sticking to 2 bytes) for these constants (0x5416 and 0x5417), so this unwanted conversion should not happen in 64bit, so we should not have the same issue with a Linux 64bit.

Pascal

On 07 Jul 2012, at 11:09, Henrik wrote:

> On 07.07.12 10:59, Jef Driesen wrote:
>> I'm not seeing any problems on 64bit linux, but maybe the actual value fits into
>> an int, and on macosx it does not? Can someone check the actual values for
>> TIOCMBIC and TIOCMBIS on 32 and 64bit macosx (using unsigned long of course).
> 
> Is this the way to do it?
> 
>    printf("%ld %ld\n", TIOCMBIS, TIOCMBIC);
> 
> In that case, I've got this for 32bit:
> 
>    -2147191700 -2147191701
> 
> ... and this for 64bit:
> 
>    2147775596 2147775595
> 
> Henrik