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# output(): Hello, world.\n

# mach(): all

# Emit hello world while switching back and forth between arm/thumb.

# ??? Unfinished

        .macro invalid

# This is "undefined" but it's not properly decoded yet.

        .word 0x07ffffff

# This is stc which isn't recognized yet.

        stc 0,cr0,[r0]

        .endm

        .global _start

_start:

# Run some simple insns to confirm the engine is at least working.

        nop

# Skip over output text.

        bl skip_output

hello_text:

        .asciz "Hello, world.\n"

        .p2align 2

skip_output:

# Prime loop.

        mov r4, r14

output_next:

# Switch arm->thumb to output next chacter.

# At this point r4 must point to the next character to output.

        adr r0, into_thumb + 1

        bx r0

into_thumb:

        .thumb

# Output a character.

        mov r0,#3 @ writec angel call

        mov r1,r4

        swi 0xab @ ??? Confirm number.

# Switch thumb->arm.

        adr r5, back_to_arm

        bx r5

        .p2align 2

back_to_arm:

        .arm

# Load next character, see if done.

        add r4,r4,#1

        sub r3,r3,r3

        ldrb r5,[r4,r3]

        teq r5,#0

        beq done

# Output a character (in arm mode).

        mov r0,#3

        mov r1,r4

        swi #0x123456

# Load next character, see if done.

        add r4,r4,#1

        sub r3,r3,r3

        ldrb r5,[r4,r3]

        teq r5,#0

        bne output_next

done:

        mov r0,#0x18

        ldr r1,exit_code

        swi #0x123456

# If that fails, try to die with an invalid insn.

        invalid

exit_code:

        .word 0x20026