From f8cc0d73afe12cc1c8dd1600a28ff4634decf617 Mon Sep 17 00:00:00 2001
From: cheapie <cheapiephp@gmail.com>
Date: Sun, 8 Nov 2026 07:38:17 -0600
Subject: Add Smrnmi

---
 rvcontroller.lua | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 55 insertions(+), 3 deletions(-)

(limited to 'rvcontroller.lua')

diff --git a/rvcontroller.lua b/rvcontroller.lua
index c4e27d6..bf9877f 100644
--- a/rvcontroller.lua
+++ b/rvcontroller.lua
@@ -640,6 +640,13 @@ local function writecsr(address,data)
 	elseif address == 0x722 then --minstretcfgh
 		mem.instretminh = explodebits(data,32)[30]
 		return
+	elseif address == 0x744 then --mnstatus
+		local oldbits = explodebits(mem.csr[0x744],32)
+		local newbits = explodebits(data,32)
+		oldbits[9] = newbits[9]
+		oldbits[3] = oldbits[3] or newbits[3]
+		mem.csr[0x744] = implodebits(oldbits,32)
+		return
 	elseif address == 0xb00 or address == 0xb02 or address == 0xb80 or address == 0xb82 then --mcycle(h)/minstret(h)
 		--Transform into cycle(h)/instret(h) (but allow the write)
 		address = address + 0x100
@@ -710,6 +717,20 @@ local function writecsr(address,data)
 	mem.csr[address] = data
 end
 
+local function rnmi(reason)
+	mem.rnmi = true
+	local mnstatusbits = explodebits(mem.csr[0x744],32)
+	writecsr(0x741,mem.registers.pc) --mnepc
+	writecsr(0x742,reason) --mncause
+	mnstatusbits[11] = 1 --mnpp[0]
+	mnstatusbits[12] = 1 --mnpp[1]
+	mnstatusbits[9] = mem.elp --mnpelp
+	mem.elp = false
+	mnstatusbits[3] = false --nmie
+	mem.registers.pc = mem.csr[0xbc0] --mnvec
+	mem.csr[0x744] = implodebits(mnstatusbits,32)
+end
+
 local function trap(reason,val)
 	if reason >= 0x8000000 then
 		--Interrupt
@@ -725,7 +746,7 @@ local function trap(reason,val)
 		end
 	end
 	local oldreason = reason
-	if mem.mdt then
+	if mem.mdt and not mem.rnmi then
 		writecsr(0x34b,reason) --mtval2
 		reason = 0x10
 	end
@@ -753,8 +774,15 @@ local function trap(reason,val)
 			mem.registers.pc = mem.trapbase
 			return true,false
 		end
+	elseif mem.csr[0x744]%16 >= 8 and not mem.rnmi then
+		rnmi(oldreason)
+		return true,false
 	else
-		digiline_send("monitordisp","Unexpected trap!")
+		if mem.rnmi then
+			digiline_send("monitordisp","Trap during NMI!")
+		else
+			digiline_send("monitordisp","Unexpected trap!")
+		end
 		if not mem.mtvecwritten then
 			digiline_send("monitordisp",traptypes[oldreason] or "Unknown reason")
 			if oldreason == 18 then
@@ -783,6 +811,7 @@ local function trap(reason,val)
 end
 
 local function checkinterrupts()
+	local mnstatusbits = explodebits(mem.csr[0x744],32)
 	local miebits = explodebits(mem.csr[0x304],32)
 	local mipbits = explodebits(mem.csr[0x344],32)
 	if mem.mtimecmphigh == mem.csr[0xc81] and (os.time() - mem.starttime) >= mem.mtimecmplow then
@@ -794,6 +823,7 @@ local function checkinterrupts()
 	end
 	mem.csr[0x344] = implodebits(mipbits,32)
 	if not mem.mie then return end
+	if not mnstatusbits[3] then return end --nmie
 	local order = {11,3,7,9,1,5,13,16,17,18}
 	for _,i in ipairs(order) do
 		if miebits[i] and mipbits[i] then
@@ -2062,6 +2092,15 @@ local operations = {
 		checkinterrupts()
 		return true
 	end,
+	mnret = function()
+		mem.registers.pc = readcsr(0x741)
+		local mnstatusbits = explodebits(mem.csr[0x744],32)
+		mnstatusbits[3] = 1 --nmie
+		mem.elp = mem.mlpe and mnstatusbits[9] --mnpelp
+		mem.csr[0x741] = implodebits(mnstatusbits,32)
+		mem.rnmi = false
+		return true
+	end,
 	wfi = function()
 		mem.interruptwaiting = true
 		mem.running = false
@@ -2524,6 +2563,8 @@ local function runinst(instruction)
 					return operations.wrssto()
 				elseif imm == 0x302 and rd == 0 and rs1 == 0 then
 					return operations.mret()
+				elseif imm == 0x702 and rd == 0 and rs1 == 0 then
+					return operations.mnret()
 				elseif imm == 0x105 and rd == 0 and rs1 == 0 then
 					return operations.wfi()
 				else
@@ -2820,7 +2861,7 @@ local function runinst(instruction)
 			return trap(2,instruction)
 		end
 	else
-		trap(2,instruction)
+		return trap(2,instruction)
 	end
 end
 
@@ -3405,6 +3446,11 @@ local csraliases = {
 	minstretcfg = 0x322,
 	mcyclecfgh = 0x721,
 	minstretcfgh = 0x722,
+	mnscratch = 0x740,
+	mnepc = 0x741,
+	mncause = 0x742,
+	mnstatus = 0x744,
+	mnvec = 0xbc0,
 }
 
 if event.type == "program" or event.iid == "reset" then
@@ -3458,6 +3504,11 @@ if event.type == "program" or event.iid == "reset" then
 			[0xc84] = 0, --hpmcounter4h
 			[0xc85] = 0, --hpmcounter5h
 			[0xc86] = 0, --hpmcounter6h
+			[0x740] = 0, --mnscratch
+			[0x741] = 0, --mnepc
+			[0x742] = 0, --mncause
+			[0x744] = 0, --mnstatus
+			[0xbc0] = 0x8000, --mnvec
 	}
 	for i=1,6 do mem.stdout[i] = "" end
 	local mdisp = event.type == "program" and "\nReset: Cold" or "\nReset: Warm"
@@ -3497,6 +3548,7 @@ if event.type == "program" or event.iid == "reset" then
 	mem.mcountinhibit = {}
 	mem.cycleminh = false
 	mem.instretminh = false
+	mem.rnmi = false
 elseif event.type == "on" or event.type == "off" then
 	local pname = string.lower(event.pin.name)
 	local pstate = pin[pname]
-- 
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