Epson S5U1C17001C, Руководство пользователя

Страница: 376 / 742

6-10
EPSOn
S5U1C17001C ManUal
(C COMPilEr PaCkagE fOr S1C17 faMily) (Ver. 1.5.0)
6 C COMPilEr
The C compiler in this package is adjusted to yield even-number bytes for the size of a structure or union as an
implementation defined feature.
accessing bit fields
Bit fields with an 8-bit or less bit width will be accessed in byte size as shown below due to the compiler
optimization processing even if the bit field is defined as an
unsigned short
type. Take this into
consideration when accessing a device or I/O memory that needs to be accessed in 16-bit size.
Program
struct IFtag {
volatile union {
volatile struct {
unsigned short DATA : 1; /* 1bit */
unsigned short Dummy : 15;
} bCTL;
unsigned short usCTL;
} rOUT;
};
struct g_GAtag {
volatile struct IFtag g_IF;
};
volatile struct g_GAtag *pg_GAtag;
main()
{
pg_GAtag = (struct g_GAtag *)0x8300;
pg_GAtag->g_IF.rOUT.bCTL.DATA = 1;
(
*
)
return;
}
Code compiled from the source line (
*
)
pg_GAtag->g_IF.rOUT.bCTL.DATA = 1;
ld.b %r3,[%r2] ;
Byte access
or %r3,0x1
ld.b [%r2],%r3 ;
Byte access