ORG  1000H
;MEMORIA
NUM DB ?
ROTA DB ?
RES  DB ?

;PROGRAMA PRINCIPAL
ORG 2000H
MOV AX,NUM
PUSH AX
MOV AX,ROTA
PUSH AX
MOV AX,OFFSET RES
PUSH AX
CALL ROTARIZQ
POP AX
POP AX
POP AX
HLT
END

;SUBRUTINAS
ORG 3000H
ROTARIZQ: PUSH BX
    MOV BX,SP
    PUSH AX
    PUSH CX
    PUSH DX
    ADD BX,6
    MOV CX,[BX]
    ADD BX,2
    MOV AX,[BX]
    CMP CX,0
    JZ FIN
ROTAR:  ADD AX,AX
  ADC AX
  DEC CX
  JNZ ROTAR
FIN: SUB BX,4
  MOV BYTE PTR [BX],AL
  POP DX
  POP CX
  POP AX
  POP BX
  RET