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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
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