From: Vince Bridgers
> On Mon, Mar 10, 2014 at 7:40 PM, Stephen Hemminger
> <stephen@xxxxxxxxxxxxxxxxxx> wrote:
> > On Mon, 10 Mar 2014 18:14:36 -0500
> > Vince Bridgers <vbridgers2013@xxxxxxxxx> wrote:
> >
> >> +
> >> + buf[0] = (u64) ioread32(&mac->frames_transmitted_ok);
> >
> > The cast to u64 is not really necessary, C will do it for you.
> > You do need the cast to do the shift for the 64 bit values.
>
> Ok, understood. I generally add the cast so it's explicit, but I'll modify.
The problem is that the cast will allow incorrect code to compile.
eg, you might have a pointer, not an integer.
Many years ago I got caught out by a #define like the following:
#define foo(ptr) { int s = splhi(); do_foo((void *)ptr); splx(s); }
My code crashed because I'd called foo(s).
Now that #define is broken in so many ways, but the (void *) cast
stopped the compiler erroring one of them.
David
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