Messages in this thread | | | Date | Sun, 26 Nov 2006 14:20:10 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [PATCH] Avoid truncating to 'long' in ALIGN() macro |
| |
On Sun, 26 Nov 2006, Roland Dreier wrote: > > > +#define ALIGN(x,a) __ALIGN_MASK(x,(typeof(x))(a)-1) > > +#define __ALIGN_MASK(x,mask) (((x)+(mask))&~(mask)) > > Fine by me, but it loses the extra (typeof(x)) cast that Al wanted to > make sure that the result of ALIGN() is not wider than x.
Well, since "mask" is now made to be of the same type as "x", every sub-expression actually has the same type, modulo the normal C behaviour of "expand to at least "int".
So arguably, the result is _more_ like a normal C operation this way. Type-wise, the "ALIGN()" macro acts like any other C operation (ie if you feed it an "unsigned char", the end result is an "int" due to the normal C type widening that happens for all C operations).
But I don't care horribly much. Al may have some other reasons to _not_ want the normal C type expansion to happen (ie maybe he does something unnatural with sparse ;)
Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |