[email protected] wrote:
Hi,
I've got a problem with msp430-gcc structure sizes / packing:
When compiling the following code with a newer version of mspgcc (e. g.
mspgcc-20081230.exe or a topic cvs-build) the variable xaver is six byte in
memory:
typedef struct {
struct {
unsigned a : 1;
unsigned b : 1;
unsigned c : 1;
unsigned d : 1;
unsigned e : 4;
} BIT;
unsigned char x;
unsigned int y;
} mytype;
mytype xaver;
int main() {
}
When compiling it with an older version (e. g. mspgcc-20080619.exe), xaver has
only a size of four bytes.
Can anybody explain me why?
Because of unsigned int base type of bitfield. It takes 2 bytes. Next field
takes one byte and one byte padded to align y to 2-bytes address boundary.
Can I avoid packing the new way?
use correct type for bitfield:
struct {
unsigned char a : 1;
......
} BIT;
--
Regards,
Sergey A. Borshch mailto: [email protected]
SB ELDI ltd. Riga, Latvia
