tiny_os/root/root.S

.macro syscall msg ptr
	li	a0, \msg
	li	a1, \ptr
	ecall
.endm

.text
	.global _start
_start:
	la	t0, msg
.loop:
	lb	a2, 0(t0)
	beqz	a2, .yield
	# msg: label = DebugPutChar(1), length = 3
	# ptr: self-referential to cspace, just to create a valid cptr
	syscall (1<<12 | 3), 0x0202020202020202
	addi	t0, t0, 1
	j	.loop
.yield:
	# msg: label = Yield(2), length = 2
	# ptr: self-referential to cspace, just to create a valid cptr
	syscall (2<<12 | 2), 0x0202020202020202
	j	_start

.data
	msg : .string "Hello, world!\n\0"