SCI32: Read byte/string array values as signed in SCI2.1early-

KQ7 1.51 writes int16s from the save game catalogue into a Str
object, then retrieves byte 0 from the string and compares it to
-1. This happens to work out because (1) characters were treated
as signed in SCI2.1early and earlier, and (2) int16s in the save
game catalogue were little-endian.

In SCI2.1mid and later, this trick no longer works because
characters are treated as unsigned and get zero-extended instead.

Fixes Trac#9632.

1 files changed, 11 insertions, 2 deletions

diff --git a/engines/sci/engine/segment.h b/engines/sci/engine/segment.h
index 361c1cb895..e8f0be3a79 100644
--- a/engines/sci/engine/segment.h
+++ b/engines/sci/engine/segment.h
@@ -552,8 +552,17 @@ public:
 		case kArrayTypeID:
 			return ((reg_t *)_data)[index];
 		case kArrayTypeByte:
-		case kArrayTypeString:
-			return make_reg(0, ((byte *)_data)[index]);
+		case kArrayTypeString: {
+			int16 value;
+
+			if (getSciVersion() < SCI_VERSION_2_1_MIDDLE) {
+				value = ((int8 *)_data)[index];
+			} else {
+				value = ((uint8 *)_data)[index];
+			}
+
+			return make_reg(0, value);
+		}
 		default:
 			error("Invalid array type %d", _type);
 		}