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; CALLING A ROUTINE AND PREPARE A MEMORY ADDRESS
; ROUTINE WILL REQUIRE 3 BYTES FIRST NUMBER -> SECOND NUMBER -> RESULT STORAGE
; ROUTINE WILL MULTIPLY M WITH M+1 AND STORE RESULT IN M+2
JMP START
; DEFINE A LIST TO STORE OUR REQUIRED BYTES
; DB = DEFINE BYTE
; DS = DEFINE STORAGE. OPERAND IS NUMBER OF BYTES
MULTI1: DB 05H ; MULTIPLICAND
DB 03H ; MULTIPLIER
DS 01H ; RESERVES "ONE BYTE OF STORAGE
START: LXI H,MULTI1 ; LOAD HL AS POINTER TO MULTI1 LIST MEMORY ADDRESS
MVI A,0 ; CLEAR A
MOV D,M ; STORE MULTIPLICAND IN D
INX H ; INCREASE MEMORY POINTER TO GET MULTIPLIER
MOV E,M ; STORE MULTIPLIER IN E
MVI C,00H ; COUNTER SET TO 0
CALL MULT ; CALL MULTIPLY FUNCTION
INX H ; INCREASE MEMORY POINTER TO RESULT STORAGE
MOV M,A ; STORE RESULT
HLT ; HALT
MULT: MOV B,A ; STORE A
MOV A,C ; MOVE COUNTER INTO A
CMP E ; COMPARE MULTIPLIER TO COUNTER
MOV A,B ; MOVE B STORAGE BACK INTO A
RZ ; RETURN IF ZERO FLAG SET (COUNTER == MULTIPLIER)
INR C ; INCREASE COUNTER
ADD D ; ADD MULTIPLICAND TO A
JMP MULT ; JUMP TO MULT
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