From 5b401215d9e0a31687c27b8b56ba3d651b89e000 Mon Sep 17 00:00:00 2001
From: Filippos Karapetis
Date: Fri, 30 Jul 2010 14:56:38 +0000
Subject: SCI: Added handling of negative numbers to op_mod for SCI01 and newer
 games. Fixes the battlecruiser mini-game in SQ5. Many thanks to lskovlun, wjp
 and m_kiewitz for their joined effort on this issue

svn-id: r51508
---
 engines/sci/engine/vm.cpp | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

(limited to 'engines/sci')

diff --git a/engines/sci/engine/vm.cpp b/engines/sci/engine/vm.cpp
index b7f6896a48..0ab66419c0 100644
--- a/engines/sci/engine/vm.cpp
+++ b/engines/sci/engine/vm.cpp
@@ -1069,11 +1069,17 @@ void run_vm(EngineState *s) {
 
 		case op_mod: { // 0x05 (05)
 			r_temp = POP32();
-			int16 modulo, value;
-			if (validate_signedInteger(s->r_acc, modulo) && validate_signedInteger(r_temp, value))
-				s->r_acc = make_reg(0, (modulo != 0 ? value % modulo : 0));
-			else
+			int16 modulo, value, result;
+			if (validate_signedInteger(s->r_acc, modulo) && validate_signedInteger(r_temp, value)) {
+				modulo = ABS(modulo);
+				result = (modulo != 0 ? value % modulo : 0);
+				// In SCI01, handling for negative numbers was added
+				if (getSciVersion() >= SCI_VERSION_01 && result < 0)
+					result += modulo;
+				s->r_acc = make_reg(0, result);
+			} else {
 				s->r_acc = arithmetic_lookForWorkaround(opcode, NULL, s->r_acc, r_temp);
+			}
 			break;
 		}
 
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