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), bits = 1, length = 3, transfer_cap = false
	# ptr: (any)
	syscall (1<<14 | 0<<8 | 3<<1 | 0), 0
	addi	t0, t0, 1
	j	.loop
.yield:
	# msg: label = Yield(2), bits = 1, length = 2, transfer_cap = false
	# ptr: (any)
	syscall (2<<14 | 0<<8 | 2<<1 | 0), 0
	j	_start

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