ex5.s

.include "configuration.inc"
.include "inter.inc"

mov r0, #0
ADDEXC 0x18, irq_handler
ADDEXC 0x1C, fiq_handler

main:

    mov r0, #0b11010010
    msr cpsr_c, r0
    mov sp, #0x8000

    mov r0, #0b11010001
    msr cpsr_c, r0
    mov sp, #0x4000

    mov r0, #0b11010011
    msr cpsr_c, r0
    mov sp, #0x8000000


    ldr r0, =STBASE
    ldr r1, [r0, #STCLO]
    add r1, #4000
    str r1, [r0, #STC1]

    ldr r0, =INTBASE
    ldr r2, =0b0010
    str r2, [r0, #INTENIRQ1]

    mov r1, #0b01010011
    msr cpsr_c, r1

    ldr r3, =0
    ldr r4, =0x010

end:    b end

fiq_handler:

irq_handler:
    ldr r0, =GPBASE
    eors r3, r3, #0b01
    streq r4, [r0, #GPSET0]
    strne r4, [r0, #GPCLR0]


    ldr r0, =STBASE
    mov r1, #0b0010
    str r1, [r0, #STCS]

    ldr r0, =STBASE
    ldr r1, [r0, #STCLO]
    add r1, #4000
    str r1, [r0, #STC1]

    subs pc, lr, #4