Richard Anderson <[EMAIL PROTECTED]> wrote:
> On the pointer front:
>
> I dont expect the compiler to change the pointer but take this
example
> (psudo addresses):
>
> I receive 3 bytes of serial data and place them at address 0x100
>
> if my data is infact:
>
> struct {
> char a;
> word b;
> } mystruct;
>
> And I have a pointer to mystruct overlayed on my serial data
>
> mystruct *ptr = 0x100;
>
> and do : word c = *mystruct->b then you get a bus error as
the
> compiler does a move.w over a odd boundary.
> What it should do is 2 * move.b and recombine the result
transparently to
> the C user. Other 68K compiler I have used do this.
Ah, okay. Are you sure about the two move.b instructions? Most
compilers I've seen that are targetted to architectures requiring even
address for multi-byte accesses accomplish such safety by adding a byte
of padding as necessary within structs, so that multi-byte elements are
on even addresses. There should be an option somewhere in the CW
settings to make it do this.
--
Roger Chaplin
<[EMAIL PROTECTED]>
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