Add interrupt based timer and test code

hw/efinix_fpga/test_programs/timer_irq.s

@@ -0,0 +1,39 @@
+.code
+
+LEDS = $efff
+TIMER_BASE = $eff8
+TIMER_DIVISOR = 2
+TIMER_CL = 0
+TIMER_LL = 0
+TIMER_CH = 1
+TIMER_LH = 1
+TIMER_STATUS = 3
+TIMER_CONTROL = 3
+TIMER_OLD = $10
+
+main:
+    lda #$ff
+    sta TIMER_BASE+TIMER_DIVISOR
+    lda #$01
+    sta TIMER_BASE+TIMER_CONTROL
+    lda #$00
+    sta TIMER_BASE+TIMER_LH
+    lda #$10
+    sta TIMER_BASE+TIMER_LL
+    cli
+
+loop:
+    wai
+    bra loop
+
+irq:
+    lda TIMER_BASE
+    inc LEDS
+    rti
+
+    
+.segment "VECTORS"
+
+.addr main
+.addr main
+.addr irq