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SubjectRe: Being more anal about iospace accesses..
Jörn Engel wrote:
> On Wed, 15 September 2004 09:30:42 -0700, Linus Torvalds wrote:
>>For example, if you don't know (or, more importantly - don't care) what
>>kind of IO interface you use, you can now do something like
>> void __iomem * map = pci_iomap(dev, bar, maxbytes);
>> ...
>> status = ioread32(map + DRIVER_STATUS_OFFSET);
> C now supports pointer arithmetic with void*? I hope the width of a
> void is not architecture dependent, that would introduce more subtle
> bugs.
> Jörn

5.18 Arithmetic on void- and Function-Pointers

In GNU C, addition and subtraction operations are supported on pointers
to void and on pointers to functions. This is done by treating the size
of a void or of a function as 1.

A consequence of this is that sizeof is also allowed on void and on
function types, and returns 1.

The option -Wpointer-arith requests a warning if these extensions are used.

Brian Gerst
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