FILTER7: CLR A MOV R2,A MOV R3,A MOV R6,A MOV R7,A MOV R4,#3FH MOV R5,#OFFH MOV R0,#4 DAVI: ;输人采样值到寄存器B,A中 MOV Rl,A ADD A, R7 MOV R7,A MOV A, B ADDC A,R6 MOV R6,A CLR C MOV A,R3 SUBB A,R1 MOV A,R2 SUBB A,B JNC DAV2 MOV A,R1 MOV R3,A MOV R2 ,B DAV2: CLR C MOV A, R1 SUBB A,R5 MOV A,B SUBB A,R4 JNC DAV3 MOV A,R1 MOV RS,A MOV R4,B DAV3: DJNZ R0,DAVI CLR C MOV A,R7 SUBB A,R3 XCH A, R6 SUBB A,R2 XCH A,R6 SUBB A,RS XCH A,R6 SUBB A,R4 CLR C RRC A XCH A,R6 RRC A MOV R7,A RET