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TR : Possible GCC bug on m68k
- Date: Wed, 03 Nov 2004 14:07:14 +0800
- From: paulw at omnitronics.com.au (Paul Whitfield)
- Subject: TR : Possible GCC bug on m68k
Chris Johns wrote:
> Hmmm. What about this example:
> /* m68k-rtems-gcc -g -c -o comp.o comp.c */
> #include <stdio.h>
> int main ()
> unsigned char l = 0xff;
> unsigned char r = 0;
> if (l == ~r)
> printf ("i) yes\n");
> printf ("i) no\n");
> if (l == (unsigned char) ~r)
> printf ("ii) yes\n");
> printf ("ii) no\n");
> return 0;
> The result on Linux is :
> $ ./comp
> i) no
> ii) yes
On windows with gcc ... result the same
On windows with BorlandC ... result the same...
For K&R Version 2: A.7.4.6 One's Complement Operator.
The operand of the ~ operator must have integral type, and the result is
the one's complement of its operand. The integral promotions are
performed. If the operand is unsigned, the result is computed
by subtracting the value from the largest value of the promoted type.
So to me (and I am not a language lawyer)... it would seem that
the operation is correct!