Add work-in-progress rrxing2 program

1 files changed, 43 insertions, 0 deletions

diff --git a/assembly/rrxing2/util.S b/assembly/rrxing2/util.S
new file mode 100644
index 0000000..9dda1ab
--- /dev/null
+++ b/assembly/rrxing2/util.S
@@ -0,0 +1,43 @@
+.macro digiline_send channel msg
+	la a0,(\channel)
+	la a1,(\msg)
+	li a7,129
+	ecall
+.endm
+
+.macro set_timeri time
+	li t0,0x80
+	csrs mie,t0 # unmask timer interrupt
+	ld t1,2(gp) # read mtime
+	li t0,(\time)
+	add t1,t1,t0 # calculate target value (lower half)
+	sltu t0,t1,t0 # check if it overflowed
+	add t2,t2,t0 # add the overflow into the high half if there was any
+	sd t1,10(gp) # set mtimecmp to the target value
+.endm
+
+.macro stop_timer
+	li t1,0xffffffff
+	li t2,0xffffffff
+	sd t1,10(gp) # set mtime to far in the future
+	li t1,0x80
+	csrc mie,t1 # mask timer interrupt
+.endm
+
+.macro set_timer_to label
+	cm.push {ra},-16
+	la a0,(\label)
+	lbu a0,0(a0)
+	call set_timer
+	cm.pop {ra},16
+.endm
+
+set_timer:
+li t0,0x80
+csrs mie,t0 # unmask timer interrupt
+ld t1,2(gp) # read mtime
+add t1,t1,a0 # calculate target value (lower half)
+sltu t0,t1,a0 # check if it overflowed
+add t2,t2,t0 # add the overflow into the high half if there was any
+sd t1,10(gp) # set mtimecmp to the target value
+ret