QA·C Help - 3305

	3305	Pointer cast to stricter alignment.

Pointers

A pointer is being cast to a pointer type which has a "stricter" alignment requirement.

The alignment of types in memory is implementation-defined. In a typical implementation, it could be a requirement of the architecture that a 4 byte int would always be allocated on a 4 byte boundary in memory while a char could be allocated at any memory address. In such circumstances, it would be safe to cast an "int *" to a "char *", but it would be dangerous to cast a "char *" to an "int *" unless the address happens to be located on a 4 byte boundary

QA·C provides the -align option to specify the implemented alignment constraint for a particular type. Message 3305 will be generated whenever a pointer is being converted to a type with a stricter alignment requirement, i.e. a larger alignment setting.

Default size and alignment settings are as follows:

TYPE	SIZE (bits)	ALIGNMENT (bytes)
char	8	1
short	16	2
int	32	4
long	32	4
long long	64	8
float	32	4
double	64	8
long double	64	8
code pointer	32	4
data pointer	32	4

For example:


/*PRQA S 310,2017,3210,3408,3447,3625,3631 ++*/

extern char  *pc;               /* one  byte aligned */
extern short *ps;               /* two  byte aligned */
extern int   *pi;               /* four byte aligned */

extern void foo(void)
{
    pi = (int*)pc;              /* Message 3305 */
    pc = (char *)pi;            /* OK */
}

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