From f533290e855dcdb9d266f147716b10e9a6268058 Mon Sep 17 00:00:00 2001
From: Ember Cold <embercold@outlook.com>
Date: Wed, 21 Jul 2021 15:04:23 +0300
Subject: [PATCH] Handle DIV overflow in lightrec and the interpreter

---
 deps/lightrec/interpreter.c  |  3 +++
 libpcsxcore/psxinterpreter.c | 22 ++++++++++++++--------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/deps/lightrec/interpreter.c b/deps/lightrec/interpreter.c
index f586685c..ff609a45 100644
--- a/deps/lightrec/interpreter.c
+++ b/deps/lightrec/interpreter.c
@@ -801,6 +801,9 @@ static u32 int_special_DIV(struct interpreter *inter)
 	if (rt == 0) {
 		hi = rs;
 		lo = (rs < 0) * 2 - 1;
+	} else if ((rs == 0x80000000) && (rt == 0xFFFFFFFF)) {
+		lo = rs;
+		hi = 0;
 	} else {
 		lo = rs / rt;
 		hi = rs % rt;
diff --git a/libpcsxcore/psxinterpreter.c b/libpcsxcore/psxinterpreter.c
index d3e42e9f..db8e73b0 100644
--- a/libpcsxcore/psxinterpreter.c
+++ b/libpcsxcore/psxinterpreter.c
@@ -507,14 +507,20 @@ void psxSLTU() 	{ if (!_Rd_) return; _rRd_ = _u32(_rRs_) < _u32(_rRt_); }	// Rd
 * Format:  OP rs, rt                                     *
 *********************************************************/
 void psxDIV() {
-	if (_i32(_rRt_) != 0) {
-		_i32(_rLo_) = _i32(_rRs_) / _i32(_rRt_);
-		_i32(_rHi_) = _i32(_rRs_) % _i32(_rRt_);
-	}
-	else {
-		_i32(_rLo_) = _i32(_rRs_) >= 0 ? 0xffffffff : 1;
-		_i32(_rHi_) = _i32(_rRs_);
-	}
+    if (!_i32(_rRt_)) {
+        _i32(_rHi_) = _i32(_rRs_);
+        if (_i32(_rRs_) & 0x80000000) {
+            _i32(_rLo_) = 1;
+        } else {
+            _i32(_rLo_) = 0xFFFFFFFF;
+        }
+    } else if (_i32(_rRs_) == 0x80000000 && _i32(_rRt_) == 0xFFFFFFFF) {
+        _i32(_rLo_) = 0x80000000;
+        _i32(_rHi_) = 0;
+    } else {
+        _i32(_rLo_) = _i32(_rRs_) / _i32(_rRt_);
+        _i32(_rHi_) = _i32(_rRs_) % _i32(_rRt_);
+    }
 }
 
 void psxDIVU() {
-- 
2.39.5