From d29584ca1361f7268511fda2404f15991ca9c5c9 Mon Sep 17 00:00:00 2001
From: cheapie <cheapiephp@gmail.com>
Date: Sun, 8 Nov 2026 08:12:18 -0600
Subject: Mask mnepc as needed on reads

---
 rvcontroller.lua | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/rvcontroller.lua b/rvcontroller.lua
index bf9877f..801178c 100644
--- a/rvcontroller.lua
+++ b/rvcontroller.lua
@@ -413,6 +413,15 @@ local function readcsr(address)
 			ret = ret - 2
 		end
 		return ret
+	elseif address == 0x741 then --mnepc
+		local ret = mem.csr[0x741]
+		--mnepc[0] must be 0
+		if ret%2 == 1 then ret = ret-1 end
+		--mnepc[1] must be 0 if IALIGN=32
+		if not mem.isa.c and ret%4 >= 2 then
+			ret = ret - 2
+		end
+		return ret
 	elseif address == 0x300 then --mstatus
 		local bits = {}
 		bits[3] = mem.mie
-- 
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