C: bdata unsigned BUFR16=0; sbit BIT8=BUFR16^8; the assemble language which is compiled by Keil uVision3: C:0x1172 9210 MOV BIT8(0x22.0),C ...... ;BUFR16<<=1; C:0x117D E522 MOV A,0x22 C:0x117F 25E0 ADD A,ACC(0xE0) C:0x1181 F522 MOV 0x22,A C:0x1183 E521 MOV A,BUFR16(0x21) C:0x1185 33 RLC A C:0x1186 F521 MOV BUFR16(0x21),A ......