Intel i960 - Natural Alignment

i960 Processor Compiler User's Guide
7-8
7
Figure 7-1 Natural Alignment
Byte 0
8
4
00 7 0 7
7
0 7
OSD829
b
a
XXXXXXXX
c
d
XXXX
Specifying a user-constrained alignment changes both the tail padding and
the padding between structure members, which can also affect the
structure size. A user-constrained alignment smaller than the natural
alignment of a structure can result in a more tightly packed structure,
saving space but slowing execution.
The example in Figure 7-2 compares the layouts in memory of the
following structure under two different user-constrained alignments:
struct strc1 /* Alignment is 2: Alignment is 1: */
{ /* --------------- --------------- */
char a; /* byte 0 byte 0 */
short b; /* bytes 2 and 3 bytes 1 and 2 */
char c; /* byte 4 byte 5 */
int d; /* bytes 6 through 9 bytes 4 through 7 */
};