timers: don't reconfigure for minor changes

Prevents the timer to be reset when changing non important
bits, like the edge detector etc

Signed-off-by: Michel Pollet <buserror@gmail.com>

diff --git a/simavr/sim/avr_timer.c b/simavr/sim/avr_timer.c
index 3912e59..a218a67 100644 (file)
--- a/simavr/sim/avr_timer.c
+++ b/simavr/sim/avr_timer.c
@@ -295,8 +295,21 @@ static void avr_timer_write_ocr(struct avr_t * avr, avr_io_addr_t addr, uint8_t
 static void avr_timer_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t v, void * param)
 {
        avr_timer_t * p = (avr_timer_t *)param;
+
+       uint8_t as2 = avr_regbit_get(avr, p->as2);
+       uint8_t cs = avr_regbit_get_array(avr, p->cs, ARRAY_SIZE(p->cs));
+       uint8_t mode = avr_regbit_get_array(avr, p->wgm, ARRAY_SIZE(p->wgm));
+
        avr_core_watch_write(avr, addr, v);
-       avr_timer_reconfigure(p);
+
+       // only reconfigure the timer if "relevant" bits have changed
+       // this prevent the timer reset when changing the edge detector
+       // or other minor bits
+       if (avr_regbit_get_array(avr, p->cs, ARRAY_SIZE(p->cs)) != cs ||
+                       avr_regbit_get_array(avr, p->wgm, ARRAY_SIZE(p->wgm)) != mode ||
+                                       avr_regbit_get(avr, p->as2) != as2) {
+               avr_timer_reconfigure(p);
+       }
 }
 
 /*