.set GPTCR, 0x53FA0000
.set GPTPR, 0x53FA0004
.set GPTOCR, 0x53FA0010
.set GPTIR, 0x53FA000C
.set GPTSR, 0x53FA0008
.set GDIR, 0x53F84004
.set DR, 0x53F84000
.set PSR, 0x53F84008
.set USERCODE, 0x77812000
.set MAX_ALARMS, 8
.set MAX_CALLBACKS, 8

.set TIME_SZ, 0x4E20


.org 0x0
.section .iv,"a"

_start:

interrupt_vector:

    b RESET_HANDLER
.org 0x08
    b SVC_HANDLER
.org 0x18
    b IRQ_HANDLER


.org 0x100
.text

RESET_HANDLER:

    @ Zera o contador
    ldr r2, =CONTADOR
    mov r0, #0
    str r0, [r2]

    @Faz o registrador que aponta para a tabela de interrupções apontar para a tabela interrupt_vector
    ldr r0, =interrupt_vector
    mcr p15, 0, r0, c12, c0, 0


    @Inicializa Pilha IRQ, interrupcoes desativadas

    msr CPSR_C, #0x92
    ldr r13, =pilhairq

    @Inicializa Pilha do Usuário, interrupções desativadas

    msr CPSR_C, #0x9F
    ldr r13, =pilhauser


    @Configura o GPT

    ldr r0, =GPTCR
    mov r1, #0x41
    str r1, [r0]

    ldr r0, =GPTPR
    mov r1, #0x0
    str r1, [r0]

    ldr r0, =GPTOCR
    ldr r1, =TIME_SZ
    str r1, [r0]

    ldr r0, =GPTIR
    mov r1, #0x10x77812000
    str r1, [r0]


    @CONFIGURA O TZIC


    SET_TZIC:
    @ Constantes para os enderecos do TZIC
    .set TZIC_BASE,             0x0FFFC000
    .set TZIC_INTCTRL,          0x0
    .set TZIC_INTSEC1,          0x84
    .set TZIC_ENSET1,           0x104
    .set TZIC_PRIOMASK,         0xC
    .set TZIC_PRIORITY9,        0x424

    @ Liga o controlador de interrupcoes
    @ R1 <= TZIC_BASE

    ldr r1, =TZIC_BASE

    @ Configura interrupcao 39 do GPT como nao segura
    mov r0, #(1 << 7)
    str r0, [r1, #TZIC_INTSEC1]

    @ Habilita interrupcao 39 (GPT)
    @ reg1 bit 7 (gpt)

    mov r0, #(1 << 7)
    str r0, [r1, #TZIC_ENSET1]

    @ Configure interrupt39 priority as 1
    @ reg9, byte 3

    ldr r0, [r1, #TZIC_PRIORITY9]
    bic r0, r0, #0xFF000000
    mov r2, #1
    orr r0, r0, r2, lsl #24
    str r0, [r1, #TZIC_PRIORITY9]

    @ Configure PRIOMASK as 0
    eor r0, r0, r0
    str r0, [r1, #TZIC_PRIOMASK]

    @ Habilita o controlador de interrupcoes
    mov r0, #1
    str r0, [r1, #TZIC_INTCTRL]


    @Inicializa Pilha do Supervisor

    msr  CPSR_c, #0x93       @ SUPERVISOR mode, IRQ/FIQ disabled
    ldr r13, =pilhasup


    @Transfere para o modo usuario, interrupcoes IRQ ativadas

    msr CPSR_C, #0x10

    @Salta para codigo de usuario

    ldr pc, =USERCODE

.align 4

IRQ_HANDLER:

   ldr r0, =GPTSR
   mov r1, #1
   str r1, [r0]
   ldr r0, =CONTADOR
   add r0, r0, #1
   str r0, =CONTADOR
   sub lr, lr, #4
   movs pc, lr

.align 4

SVC_HANDLER:

   msr  CPSR_c, #0x93    @Modo Supervisor, interrupções FIQ desativadas
   sub lr, lr, #4
   cmp r7, #16
   beq read_sonar
   cmp r7, #17
   beq register_proximity_callbacks
   cmp r7, #18
   beq set_motor_speed
   cmp r7, #19
   beq set_motors_speed
   cmp r7, #20
   beq get_time
   cmp r7, #21
   beq set_time
   cmp r7, #22
   beq set_alarm


@Tratamento das chamadas de sistema

.align 4

read_sonar:



.align 4

register_proximity_callbacks:


.align 4

set_motor_speed:

    cmp r1, #0
    blt invalid_speed
    cmp r1, #63
    bhi invalid_speed

    push {r2, r3}
    cmp r0, #1
    beq motor_1
    cmp r0, #0
    beq motor_0
    mov r0, #-1

    movs pc, lr

    invalid_speed:
        mov r0, #-2
        movs pc, lr

    motor_0:
        ldr r2, =GDIR
        and r2, r2, #0xFE03FFFF @ Máscara que zera os bits de 18 a 24
        add r2, r2, #0x1FC0000 @ Máscara que seta os bits de 18 a 24 como saída
        str r2, =GDIR
        ldr r2, =DR
        and r2, r2, #0xFE03FFFF @ Máscara que zera os bits de 18 a 24
        mov r3, #0
        add r3, r1, lsl #19 @ Máscara que coloca os bits de entrada na posição correta
        add r3, r3, #0x40000 @ Seta o bit de write
        orr r2, r2, r3
        str r2, =DR
        pop {r2, r3}
        movs pc, lr

    motor_1:
        ldr r2, =GDIR
        and r2, r2, #0x01FFFFFF @ Máscara que zera os bits de 25 a 31
        add r2, r2, #0xFE000000 @ Máscara que seta os bits de 25 a 31 como saída
        str r2, =GDIR
        ldr r2, =DR
        and r2, r2, #0x01FFFFFF @ Máscara que zera os bits de 25 a 31
        mov r3, #0
        add r3, r1, lsl #26 @ Máscara que coloca os bits de entrada na posição correta
        add r3, r3, #0x2000000 @ Seta o bit de write
        orr r2, r2, r3
        str r2, =DR
        pop {r2, r3}
        movs pc, lr

.align 4

set_motors_speed:

    cmp r1, #0
    blt invalid_1
    cmp r1, #63
    bhi invalid_1
    cmp r0, #0
    blt invalid_0
    cmp r0, #63
    blt invalid_0

    b motors


    invalid_1:
        mov r0, #-2
        movs pc, lr

    invalid_0:
        mov r0, #-1
        movs pc, lr

    motors:

        push {r2, r3}
        ldr r2, =GDIR
        and r2, r2, #0xFE03FFFF @ Máscara que zera os bits de 18 a 24
        add r2, r2, #0x1FC0000 @ Máscara que seta os bits de 18 a 24 como saída
        str r2, =GDIR
        ldr r2, =DR
        and r2, r2, #0xFE03FFFF @ Máscara que zera os bits de 18 a 24
        mov r3, #0
        add r3, r0, lsl #19 @ Máscara que coloca os bits de entrada na posição correta
        add r3, r3, #0x40000 @ Seta o bit de write
        orr r2, r2, r3
        str r2, =DR

        ldr r2, =GDIR
        and r2, r2, #0x01FFFFFF @ Máscara que zera os bits de 25 a 31
        add r2, r2, #0xFE000000 @ Máscara que seta os bits de 25 a 31 como saída
        str r2, =GDIR
        ldr r2, =DR
        and r2, r2, #0x01FFFFFF @ Máscara que zera os bits de 25 a 31
        mov r3, #0
        add r3, r1, lsl #26 @ Máscara que coloca os bits de entrada na posição correta
        add r3, r3, #0x2000000 @ Seta o bit de write
        orr r2, r2, r3
        str r2, =DR
        pop {r2, r3}
        movs pc, lr

.align 4

get_time:
    ldr r0, =CONTADOR
    movs pc, lr

.align 4

set_time:
    str r0, =CONTADOR
    movs pc, lr

.align 4

set_alarm:
    push {r2}
    ldr r2, =ALARMS
    cmp r1, CONTADOR
    blt lower_timer
    cmp r2, MAX_ALARMS
    bhi alarm_overflow
    add r2, r2, #1
    str r2, =ALARMS
    pop {r2}
    mov pc, r0
    movs pc, lr

    alarm_overflow:
        mov r0, #-1
        pop {r2}
        movs pc, lr

    lower_timer:
        mov r0, #-2
        pop {r2}
        movs pc,lr



.data @ Seção de Dados

CONTADOR: .word 0
ALARMS: .word 0
CALLBACKS: .word 0


.skip 500
pilhasup:
.skip 500
pilhauser:
skip 500
pilhairq: