Re: char alignment on ARM

[Michael Eager <eager at eagercon dot com>]

Inder wrote:
> Hi All
> I have similar question as for arm
> http://gcc.gnu.org/ml/gcc/2007-01/msg00691.html
> consider the following program.
> e.g..
> ----------------- align.c -----------------
> int main()
> {
> int bc;
> char a[6];
> int ac;
>
> bc = 0xffffffff;
> /* fill with zeros.  */
> a[0] = 0x00;
> a[1] = 0x01;
>  a[2] = 0x02;
>   a[3] = 0x03;
>    a[4] = 0x04;
>     a[5] = 0x05;
>     
>     ac=0xeeeeeeee;
> make(a);
> }
> void make(char* a)
> {
> *(unsigned long*)a = 0x12345678;
> }

> Is the compiler doing a right thing or is it a bug??

Your code is not Standard C.

If you want to treat the same memory locations as
different data types, use a union:

  union {
    long l;
    char c[4];
  } a;

  a.l = 0x12345678;
  a.c[0] = 0x01;

--
Michael Eager	 eager@eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077