; t2_5 CALL CMUL
       ORG 2000H
       MOV R0,#20H
       MOV R1,#40H
       MOV R3,#02H
       MOV SP,#07H
       LCALL CMUL
       ORGD 20H
DATA1: DB 01H,25H
       ORGD 40H
DATA2: DB 00H,25H
; CMUL
       ORG 3000H
; 2.5  P_55     CMUL
CMUL:  MOV     A,R3
       MOV     R6,A
       ADD     A,R3
       MOV     R2,A
       MOV     A,R3
       ADD     A,R0
       MOV     R0,A
       MOV     A,R1
       ADD     A,R3
       DEC     A
       MOV     R1,A
       CLR     A
 CMUL1: MOV    @R0,A
       INC     R0
       DJNZ    R6,CMUL1
       MOV     A,R2
       MOV     R6,A
       DEC     R0
CMUL2: CLR     A
CMUL3: XCH     A,@R0
       SWAP    A
       XCHD    A,@R0
       XCH     A,@R0
       DEC     R0
       DJNZ    R2,CMUL3
       MOV     R7,A
       JZ      CMUL7
CMUL4: MOV     A,R3
       MOV     R2,A
       ADD     A,R3
       ADD     A,R0
       MOV     R0,A
       CLR     C
CMUL5: MOV     A,@R0
       ADDC    A,@R1
       DA      A
       MOV     @R0,A
       DEC     R0
       DEC     R1
       DJNZ    R2,CMUL5
       MOV     A,R3
       MOV     R2,A
CMUL6: CLR     A
       ADDC    A,@R0
       DA      A
       MOV     @R0,A
       DEC     R0
       DJNZ    R2,CMUL6
       MOV     A,R3
       ADD     A,R1
       MOV     R1,A
       DJNZ    R7,CMUL4
CMUL7: MOV     A,R3
       ADD     A,R3
       MOV     R2,A
       ADD     A,R0
       MOV     R0,A
       DJNZ    R6,CMUL2
       RET
       END