Re: C programming on ARM

On 2008-01-30, Wilco Dijkstra <Wilco_dot_Dijkstra@xxxxxxxxxxxx> wrote:

"Hans-Bernhard Bröker" <HBBroeker@xxxxxxxxxxx> wrote in message news:fnr0vs$mp6$00$1@xxxxxxxxxxxxxxxxxxxx
Wilco Dijkstra wrote:

With any byte addressable architecture, a pointer is just a pointer.

But there are quite a few non-byte addressable architectures out there.
Including ARM, last I checked.

Actually most architectures are byte addressable, including ARM,

Depends on what exactly you mean by the term.

AFAIK ARM7 is byte-addressable only for bytes, but not for larger objects. Well, may be it's just me, but I wouldn't
call what happens when an ARM7 accesses a 32-bit integer without 4-byte alignment "addressing".

Obviously not all possible pointer values are valid for all types. This doesn't
affect byte addressability as casting between char* and int* doesn't lose
information. Accessing a misaligned pointer will result in an exception

On some systems. On others you just get garbage values.

(which is a good way to detect corrupted pointers). However if
you use the correct type (eg. __packed int *p rather than int
*p), the compiler will generate an unaligned access.

I tried to figure out how to do that using gcc, but never I
seemed to get the declarations or typedefs right...

--
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