atmega: esercizio 1

.include "8535def.inc"  ;nomi registri

.CSEG           ;mem prog
.ORG 0x000
    rjmp    RESET       ;reset  0x000
    rjmp    int_0_int   ;int0   0x001
    reti                ;int1   0x002
    reti                ;tim2 comp  0x003
    reti                ;tim2 ovf   0x004
    reti                ;tim1 capt  0x005
    reti                ;tim1 compB 0x006
    reti                ;tim1 compA 0x007
    reti                ;tim1 ovf   0x008
    reti                ;tim0 ovf   0x009
    reti                ;SPI STC    0x00A
    reti                ;UART RX    0x00B
    reti                ;UART UDRE  0x00C
    reti                ;UART TX    0x00D
    reti                ;ADC    0x00E
    reti                ;EE_RDY 0x00F
    reti                ;ANA_COMP   0x010

DOVE:.DW 0b0010010100110010

RESET:
    ldi r16, LOW(RAMEND)
    out SPL, r16
    ldi r16, HIGH(RAMEND)
    out SPH, r16

MAIN:
    sei
    push r17
    ;configuro int0 e sleep mode
    in r17, MCUCR
    ori r17, 0b01000011     ;set SE & int0 rising
    out MCUCR, r17
    in r17, GIMSK
    ori r17, 0b01000000     ;enable int0
    out GIMSK, r17
    ;configuro porte A e B
    ser r17
    out DDRA, r17
    out DDRB, r17
    out DDRC, r17
    ;wait
    sleep
    pop r17
    ret

int_0_int:  ;devo contare coppie di '10'
    push r17
    push r18
    push r19
    push r20
    push r21
    push r22
    ;indirizzo in z per lpm
    ldi ZL, low(DOVE*2) ;Word addressing
    ldi ZH, high(DOVE*2)
    lpm
    mov r17, r0
    ;resetto tutto
    clr r18     ;contatore loop
    clr r19     ;contatore coppie
    clr r20     ;res
    clr r21     ;temp
    clr r22     ;res
    out PORTA, r18
    out PORTB, r18
    ;via al conteggio
    mov r21 ,r17
    mov r22, ZL
    inc r22
    loop:
        andi r21, 0x03  ;considero solo ultimi due bit
        cpi r21, 0x02   ;uguale 10?
        breq n_inc      ;n++
    ritorna:
        lsr r17         ;shift right
        inc r18         ;contatore++
        cpi r18, 0x08   ;7 confronti
        brne loop
    cp r22, ZL
    breq fattoriale
    inc ZL          ;parte alta di Z
    lpm     ;carico parte alta di DOVE
    mov r17, r0
    mov r21 ,r17
    clr r18
    rjmp loop

n_inc:
    cpi r19, 0xFF       ;se contatore pieno err
    breq err
    inc r19
    rjmp ritorna


fattoriale:
    mov r17, r19    ;r17 contatore loop temp
    mov r18, r19    ;r18 contatore loop
    mov r21, r19    ;r21 somma
    mov r22, r19    ;r22 valore attuale
    loopL:
        add r19, r21
        adc r20, r22        ;sommo i riporti
        dec r17
        cpi r17, 0x00
        breq loopH
        brlt err
        rjmp loopL
    loopH:
        mov r21, r19
        dec r18
        cpi r18, 0x01
        breq print
        mov r17, r18                ;fattoriale fa 5+5+5+5=20+20+20=60+60

print:
    out PORTA, r19
    out PORTB, r20



    pop r22
    pop r21
    pop r20
    pop r19
    pop r18
    pop r17
    rjmp RESET

err:
    ldi r17, 0xFF
    out PORTC, r17
    pop r22
    pop r21
    pop r20
    pop r19
    pop r18
    pop r17
    rjmp RESET