看IAR：
#ifdef __IAR_SYSTEMS_ICC__
#define GET_IO_BITFIELD(addr) (*(( __io volatile bitfield *)(addr)))
#define __GET_IO_BIT(addr,b) GET_IO_BITFIELD(addr).bit##b
#define GET_IO_BIT(addr,b) __GET_IO_BIT(addr,b)
#else
#define GET_IO_BITFIELD(addr) GET_BITFIELD(addr)
#define GET_IO_BIT(addr,b) GET_BIT(addr,b)
#endif
#define TEST_IO GET_IO_BIT(&PORTB,PB0)
看编译出来的汇编代码：
TEST_IO =1;
SBI 0x05, 0x00
TEST_IO =0;
CBI 0x05, 0x00
TEST_IO =!TEST_IO;
IN R16, 0x05
SBRS R16, 0
SBI 0x05, 0x00
SBRC R16, 0
CBI 0x05, 0x00
TEST_IO =~TEST_IO;
IN R16, 0x05
SBRS R16, 0
SBI 0x05, 0x00
SBRC R16, 0
CBI 0x05, 0x00 |
