SCI: Refactor relocation code

This groundwork enables an object to look up its static name
separately from the normal process that is used to populate
Object::_variables when an object is first constructed.

(The static name property needs to be able to be retrieved from
objects inside of earlier save games whose name properties may
have already been modified at runtime, so the code cannot simply
pluck the value out of Object::_variables when they are first
initialised and then persisted into the save game, as nice and
easy as that would have been.)

This commit also helps to clarify the situation with relocation
tables in SCI1 games that start with a zero entry.

Refs Trac#9780.

1 files changed, 28 insertions, 5 deletions

diff --git a/engines/sci/engine/script.h b/engines/sci/engine/script.h
index 65f3ffb6ab..b59f87f13a 100644
--- a/engines/sci/engine/script.h
+++ b/engines/sci/engine/script.h
@@ -56,6 +56,10 @@ enum ScriptOffsetEntryTypes {
 	SCI_SCR_OFFSET_TYPE_SAID
 };
 
+enum {
+	kNoRelocation = 0xFFFFFFFF
+};
+
 struct offsetLookupArrayEntry {
 	uint16    type;       // type of entry
 	uint16    id;         // id of this type, first item inside script data is 1, second item is 2, etc.
@@ -105,6 +109,13 @@ public:
 	uint32 getScriptSize() const { return _script.size(); }
 	uint32 getHeapSize() const { return _heap.size(); }
 	uint32 getBufSize() const { return _buf->size(); }
+	inline uint32 getHeapOffset() const {
+		if (getSciVersion() >= SCI_VERSION_1_1 && getSciVersion() <= SCI_VERSION_2_1_LATE) {
+			return _script.size();
+		}
+
+		return 0;
+	}
 
 	const byte *getBuf(uint offset = 0) const { return _buf->getUnsafeDataAt(offset); }
 	SciSpan<const byte> getSpan(uint offset) const { return _buf->subspan(offset); }
@@ -247,7 +258,7 @@ public:
 	 * Finds the pointer where a block of a specific type starts from,
 	 * in SCI0 - SCI1 games
 	 */
-	SciSpan<const byte> findBlockSCI0(ScriptObjectTypes type, bool findLastBlock = false);
+	SciSpan<const byte> findBlockSCI0(ScriptObjectTypes type, bool findLastBlock = false) const;
 
 	/**
 	 * Syncs the string heap of a script. Used when saving/loading.
@@ -276,23 +287,35 @@ public:
 	uint16 getOffsetStringCount() { return _offsetLookupStringCount; };
 	uint16 getOffsetSaidCount() { return _offsetLookupSaidCount; };
 
+	/**
+	 * @returns kNoRelocation if no relocation exists for the given offset,
+	 * otherwise returns a delta for the offset to its relocated position.
+	 */
+	uint32 getRelocationOffset(const uint32 offset) const;
+
 private:
 	/**
+	 * Returns a Span containing the relocation table for a SCI0-SCI2.1 script.
+	 * (The SCI0-SCI2.1 relocation table is simply a list of all of the
+	 * offsets in the script heap whose values should be treated as pointers to
+	 * objects (vs just being numbers).)
+	 */
+	const SciSpan<const uint16> getRelocationTableSci0Sci21() const;
+
+	/**
 	 * Processes a relocation block within a SCI0-SCI2.1 script
 	 *  This function is idempotent, but it must only be called after all
 	 *  objects have been instantiated, or a run-time error will occur.
-	 * @param obj_pos	Location (segment, offset) of the block
 	 */
-	void relocateSci0Sci21(reg_t block);
+	void relocateSci0Sci21(const SegmentId segmentId);
 
 #ifdef ENABLE_SCI32
 	/**
 	 * Processes a relocation block within a SCI3 script
 	 *  This function is idempotent, but it must only be called after all
 	 *  objects have been instantiated, or a run-time error will occur.
-	 * @param obj_pos	Location (segment, offset) of the block
 	 */
-	void relocateSci3(reg_t block);
+	void relocateSci3(const SegmentId segmentId);
 #endif
 
 	bool relocateLocal(SegmentId segment, int location);