SCI: Adapt the segment and offset getters/setters for SCI3

This is by no means complete, but it's a good start. It is based on an
earlier discussion on the subject, and it allows us to use the highest
two bits from the segment for offset addresses

2 files changed, 44 insertions, 18 deletions

diff --git a/engines/sci/engine/vm_types.cpp b/engines/sci/engine/vm_types.cpp
index 5327dd1a2e..00b55c64b3 100644
--- a/engines/sci/engine/vm_types.cpp
+++ b/engines/sci/engine/vm_types.cpp
@@ -28,6 +28,43 @@
 
 namespace Sci {
 
+SegmentId reg_t::getSegment() const {
+	if (getSciVersion() <= SCI_VERSION_2_1) {
+		return _segment;
+	} else {
+		// Return the lower 14 bits of the segment
+		return (_segment & 0x3FFF);
+	}
+}
+
+void reg_t::setSegment(SegmentId segment) {
+	if (getSciVersion() <= SCI_VERSION_2_1) {
+		_segment = segment;
+	} else {
+		// Set the lower 14 bits of the segment, and preserve the upper 2 ones for the offset
+		_segment = (_segment & 0xC000) | (segment & 0x3FFF);
+	}
+}
+
+uint32 reg_t::getOffset() const {
+	if (getSciVersion() <= SCI_VERSION_2_1) {
+		return _offset;
+	} else {
+		// Return the lower 16 bits from the offset, and the 17th and 18th bits from the segment
+		return ((_segment & 0xC000) << 2) | _offset;
+	}
+}
+
+void reg_t::setOffset(uint32 offset) {
+	if (getSciVersion() <= SCI_VERSION_2_1) {
+		_offset = offset;
+	} else {
+		// Store the lower 16 bits in the offset, and the 17th and 18th bits in the segment
+		_offset = offset & 0xFFFF;
+		_segment = ((offset & 0x30000) >> 2) | (_segment & 0x3FFF);
+	}
+}
+
 reg_t reg_t::lookForWorkaround(const reg_t right, const char *operation) const {
 	SciTrackOriginReply originReply;
 	SciWorkaroundSolution solution = trackOriginAndFindWorkaround(0, arithmeticWorkarounds, &originReply);
diff --git a/engines/sci/engine/vm_types.h b/engines/sci/engine/vm_types.h
index 22bd8beaa1..a181bf19cd 100644
--- a/engines/sci/engine/vm_types.h
+++ b/engines/sci/engine/vm_types.h
@@ -35,36 +35,25 @@ struct reg_t {
 	SegmentId _segment;
 	uint16 _offset;
 
-	inline SegmentId getSegment() const {
-		return _segment;
-	}
-
-	inline void setSegment(SegmentId segment) {
-		_segment = segment;
-	}
-
-	inline uint16 getOffset() const {
-		return _offset;
-	}
-
-	inline void setOffset(uint16 offset) {
-		_offset = offset;
-	}
+	SegmentId getSegment() const;
+	void setSegment(SegmentId segment);
+	uint32 getOffset() const;
+	void setOffset(uint32 offset);
 
 	inline void incOffset(int16 offset) {
 		setOffset(getOffset() + offset);
 	}
 
 	inline bool isNull() const {
-		return (_offset | getSegment()) == 0;
+		return (getOffset() | getSegment()) == 0;
 	}
 
 	inline uint16 toUint16() const {
-		return _offset;
+		return (uint16)getOffset();
 	}
 
 	inline int16 toSint16() const {
-		return (int16)_offset;
+		return (int16)getOffset();
 	}
 
 	bool isNumber() const {