for built-ins gcc takes into account alignement.
So, if gcc knows, that something aligned by 2 it uses world operations,
otherwise byte ones.
Packed does not mean the structure misaligned.
It depends on data types of the structure.
For example:
struct {
char a;
int b;
};
isn't aligned by world boundary.
struct { int a,b}
aligned.
Even more -- if the structure aligned and its size is not even, gcc will use
world operations for thhis structure size()-1 and byte operation for a last
byte of it.
cheers,
~d
On Monday 02 February 2004 15:56, G Halkes wrote:
> The documentation for the msp430 libc mentions a
> problem with memcpy where you copy 2 bytes. This
> problem is caused because the compiler does not take
> the alignment into account when using a builtin for
> this function. Also, when you use structs with the
> attribute 'packed' (causing the data to be misaligned)
> you get problems. These can all be solved by setting
> the STRICT_ALIGNMENT flag.
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