# This Code derived from xv6-riscv (64bit)
# -- https://github.com/mit-pdos/xv6-riscv/blob/riscv/kernel/swtch.S

.globl sys_timer
.align 4
sys_timer:
	# call the C timer_handler(reg_t epc, reg_t cause)
	csrr	a0, mepc
	csrr	a1, mcause
	call	timer_handler

	# timer_handler will return the return address via a0.
	csrw	mepc, a0

	mret # back to interrupt location (pc=mepc)