On actual hardware, memory accesses seem to wrap.

Author: dgeelen

simavr/sim/sim_core.c

@@ -124,12 +124,11 @@ _avr_flash_read16le(
 void avr_core_watch_write(avr_t *avr, uint16_t addr, uint8_t v)
 {
 	if (addr > avr->ramend) {
-		AVR_LOG(avr, LOG_ERROR, FONT_RED
-				"CORE: *** Invalid write address "
-				"PC=%04x SP=%04x O=%04x Address %04x=%02x out of ram\n"
-				FONT_DEFAULT,
-				avr->pc, _avr_sp_get(avr), _avr_flash_read16le(avr, avr->pc), addr, v);
-		crash(avr);
+		AVR_LOG(avr, LOG_WARNING,
+				"CORE: *** Wrapping write address "
+				"PC=%04x SP=%04x O=%04x v=%02x Address %04x %% %04x --> %04x\n",
+				avr->pc, _avr_sp_get(avr), _avr_flash_read16le(avr, avr->pc), v, addr, (avr->ramend+1), addr % (avr->ramend+1));
+		addr = addr % (avr->ramend+1);
 	}
 	if (addr < 32) {
 		AVR_LOG(avr, LOG_ERROR, FONT_RED
@@ -161,12 +160,12 @@ void avr_core_watch_write(avr_t *avr, uint16_t addr, uint8_t v)
 uint8_t avr_core_watch_read(avr_t *avr, uint16_t addr)
 {
 	if (addr > avr->ramend) {
-		AVR_LOG(avr, LOG_ERROR, FONT_RED
-				"CORE: *** Invalid read address "
-				"PC=%04x SP=%04x O=%04x Address %04x out of ram (%04x)\n"
+		AVR_LOG(avr, LOG_WARNING,
+				"CORE: *** Wrapping read address "
+				"PC=%04x SP=%04x O=%04x Address %04x %% %04x --> %04x\n"
 				FONT_DEFAULT,
-				avr->pc, _avr_sp_get(avr), _avr_flash_read16le(avr, avr->pc), addr, avr->ramend);
-		crash(avr);
+				avr->pc, _avr_sp_get(avr), _avr_flash_read16le(avr, avr->pc), addr, (avr->ramend+1), addr % (avr->ramend+1));
+		addr = addr % (avr->ramend+1);
 	}
 
 	if (avr->gdb) {