From 14d7c1147fc7485920460e99498ca26489e3ccbc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?MrSm=C3=B6r?= <66489839+MrSmoer@users.noreply.github.com>
Date: Mon, 10 Nov 2025 19:25:25 +0100
Subject: [PATCH] Fix: Ignore lower z bits when erasing flash for
 page-alignment

Previously it was possible to erase the size of a page not page aligend.
Documentation of atmega328 and atmega2560 states that for the erase operation
the lower bits of z are ignored. (I guess it wouldn't make sense to not erase
page aligned as well :)
---
 simavr/sim/avr_flash.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/simavr/sim/avr_flash.c b/simavr/sim/avr_flash.c
index 0d67787e..ec5b8aeb 100644
--- a/simavr/sim/avr_flash.c
+++ b/simavr/sim/avr_flash.c
@@ -127,7 +127,7 @@ avr_flash_ioctl(
 				avr_cycle_timer_cancel(avr, avr_progen_clear, p);
 
 				if (avr_regbit_get(avr, p->pgers)) {
-					z &= ~1;
+					z &= ~(p->spm_pagesize - 1);
 					AVR_LOG(avr, LOG_TRACE, "FLASH: Erasing page %04x (%d)\n", (z / p->spm_pagesize), p->spm_pagesize);
 					for (int i = 0; i < p->spm_pagesize; i++)
 						avr->flash[z++] = 0xff;