reset:
br always >main
nop
hardfault:
reti
nop
memfault:
reti
nop

.align
segment_addr: .word 0x000F00A0

w_cnt_top:  .word 0xFFC000
// w_cnt_top:    .word 0x100 //for simulation only

write_and_shift:
    .word 0x01000100

main:
    ldr r8, >w_cnt_top
    ldr r0, >segment_addr
    ldr r1, >write_and_shift

number_loop:
    // 0 1 2 3 4 5 6 7
    clr r4
    addi r4, 0x0
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0x1
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0x2
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0x3
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0x4
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0x5
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0x6
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0x7
    or r4, r4, r1
    st32 r0, r4

    call >wait
    nop

    // 8 9 A B C D E F
    clr r4
    addi r4, 0x8
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0x9
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xA
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xB
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xC
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xD
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xE
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xF
    or r4, r4, r1
    st32 r0, r4

    call >wait
    nop

    // 0xDEADBEEF pattern:
    clr r4
    addi r4, 0xF
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xE
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xE
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xB
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xD
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xA
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xE
    or r4, r4, r1
    st32 r0, r4

    clr r4
    addi r4, 0xD
    or r4, r4, r1
    st32 r0, r4

    call >wait
    nop

    br always >number_loop
    nop


//subroutine to iterate until counter overflow
wait:
    clr r7                //inititalize inner counter
    inc_i:
    cmp neq r7,r8
    br true >inc_i        //if i=cnt_top
    addi r7,1
    ret                    //else
    nop