Intel 8080 - B4_Page_30

Chapter 6. Programming Techniques
6-10
The following reentrant program uses the Band C registers to hold the dividend and quotient, and the D and E
register
to hold the divisor and remainder. The Hand L registers are used to store data temporarily.
DIV:
MOV
CMA
MOV
MOV
CMA
MOV
INX
LXI
MVI
DVO:
PUSH
DAD
INC
XTHL
DVl:
POP
PUSH
MOV
RAL
MOV
MOV
RAL
MOV
MOV
RAL
MOV
MOV
RAL
MOV
POP
DCR
JNZ
;POST-DIVIDE CLEAN UP
A,D
D,A
A,E
E,A
D
H,O
A,I7
H
D
DVI
H
PSW
A,C
C,A
A,B
B,A
A,L
L,A
A,H
H,A
PSW
A
DVO
;NEGATE THE DIVISOR
;FOR TWO'S COMPLEMENT
;INITIAL VALUE FOR REMAINDER
;INITIALIZE LOOP COUNTER
;SAVE REMAINDER
;SUBTRACT DIVISOR (ADD NEGATIVE)
;UNDER FLOW, RESTORE HL
;SAVE LOOP COUNTER (A)
;4 REGISTER LEFT SHIFT
;WITH
CARRY
;CY->C>B >L->H
;RESTORE LOOP COUNTER (A)
;DECREMENT
IT
;KEEP LOOPING
;SHIFT
REMAINDER RIGHT AND RETURN IN DE
ORA
A
MOV
A,H
RAR
MOV
D,A
MOV
A,L
RAR
MOV
E,A
RET
END