The X 86 Microprocessors: Architecture, Programming and Interfacing (8086 to Pentium) 2nd Edition by Pearson

PROGRAMMING CONCEPTS–III 4-35

L DB -9

QUO DB?

.CODE

.STARTUP

MOV AL, X ;copy X to AL

MOV BL, Y ;copy Y to BL

CALL MULT ;call the procedure to multiply X and Y

MOV CX, AX ;copy the product to CX

MOV AL, Z ;copy Z to AL

MOV BL, AL ;copy Z to BL as well

CALL MULT ;call the procedure to get Z

2

SUB CX, AX ;compute XY—Z

2

XCHG CX, AX ;exchange CX and AX, to get dividend in AX

IDIV L ;signed division by L

MOV QUO, AL ;copy the quotient to memory

.EXIT

MULT PROC NEAR ;define the MULT procedure

IMUL BL ;multiply AL by BL, product in AX

RET ;return to calling program

MULT ENDP ;end the procedure

END

In this program, the operands are positive as w ...