[maemo-developers] DSP vs. ARM endianness and struct packing

[From: Bob Lees]

Simon

What happens if you pack the structure as in

typedef struct __attribute__ ((packed)) endian_test_struct {

Bob

On Friday 14 September 2007 12:08, Simon Pickering wrote:
> > Using the following struct on the DSP-side:
> >
> > typedef struct endian_test_struct {
> >     unsigned long iamulong1;
> >     unsigned int iamuint1;
> >     unsigned int iamuint2;
> >     unsigned long iamulong2;
> >     unsigned int iamuint3;
> >     unsigned long iamulong3;
> > } endian_test_struct;
>
> I should qualify this:
>
> On the DSP the types have the following sizes:
>
> Char = short = int = 16bit
> Long = 32bit
>
> > For comparison here's the same struct filled and viewed on
> > the ARM (with no
> > optimisation flags):
>
> Ah, my mistake, I thought I'd altered the types of the struct members on
> the ARM side to be the same sizes as on the DSP side; I was going to email
> and give the correct struct for the ARM side, but it looks like I copied
> the wrong one (i.e. the same member types which are all 32bit on the ARM).
> So ignore the ARM results for now, I'll re-do those.
>
> /me slopes away slightly embarrassed
>
>
> Simon
>
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