Some cleanup for the script debugger code:

- Renamed struct DebugState to ScriptState and r_amp_rest to restAdjust inside EngineState. Changed restAdjust to be a uint16 (actually it is a uint16, but it was being casted back and forth from an unsigned integer, so this clears up its type and size)
- Moved the script state variables from inside the run_vm() into the ScriptState struct, so that they can be accessed by the console commands and the script debugger all the time, and removed the weird isValid code

svn-id: r42260

8 files changed, 197 insertions, 251 deletions

diff --git a/engines/sci/engine/game.cpp b/engines/sci/engine/game.cpp
index 861294cfa6..5b4c30f6b3 100644
--- a/engines/sci/engine/game.cpp
+++ b/engines/sci/engine/game.cpp
@@ -365,7 +365,7 @@ int script_init_engine(EngineState *s) {
 
 
 	s->r_acc = s->r_prev = NULL_REG;
-	s->r_amp_rest = 0;
+	s->restAdjust = 0;
 
 	s->_executionStack.clear();    // Start without any execution stack
 	s->execution_stack_base = -1; // No vm is running yet
diff --git a/engines/sci/engine/kevent.cpp b/engines/sci/engine/kevent.cpp
index 744a965ef3..c4b3f5d71a 100644
--- a/engines/sci/engine/kevent.cpp
+++ b/engines/sci/engine/kevent.cpp
@@ -88,12 +88,12 @@ reg_t kGetEvent(EngineState *s, int funct_nr, int argc, reg_t *argv) {
 	case SCI_EVT_KEYBOARD:
 		if ((e.buckybits & SCI_EVM_LSHIFT) && (e.buckybits & SCI_EVM_RSHIFT) && (e.data == '-')) {
 			printf("Debug mode activated\n");
-			debugState.seeking = kDebugSeekNothing;
-			debugState.runningStep = 0;
+			scriptState.seeking = kDebugSeekNothing;
+			scriptState.runningStep = 0;
 		} else if ((e.buckybits & SCI_EVM_CTRL) && (e.data == '`')) {
 			printf("Debug mode activated\n");
-			debugState.seeking = kDebugSeekNothing;
-			debugState.runningStep = 0;
+			scriptState.seeking = kDebugSeekNothing;
+			scriptState.runningStep = 0;
 		} else {
 			PUT_SEL32V(obj, type, SCI_EVT_KEYBOARD); // Keyboard event
 			s->r_acc = make_reg(0, 1);
@@ -137,8 +137,8 @@ reg_t kGetEvent(EngineState *s, int funct_nr, int argc, reg_t *argv) {
 		s->r_acc = NULL_REG; // Unknown or no event
 	}
 
-	if ((s->r_acc.offset) && (debugState.stopOnEvent)) {
-		debugState.stopOnEvent = false;
+	if ((s->r_acc.offset) && (scriptState.stopOnEvent)) {
+		scriptState.stopOnEvent = false;
 
 		// A SCI event occured, and we have been asked to stop, so open the debug console
 		Console *con = ((Sci::SciEngine*)g_engine)->getSciDebugger();
diff --git a/engines/sci/engine/kmisc.cpp b/engines/sci/engine/kmisc.cpp
index 8381bc2e13..7e0aca5b7a 100644
--- a/engines/sci/engine/kmisc.cpp
+++ b/engines/sci/engine/kmisc.cpp
@@ -96,8 +96,8 @@ reg_t kFlushResources(EngineState *s, int funct_nr, int argc, reg_t *argv) {
 reg_t kSetDebug(EngineState *s, int funct_nr, int argc, reg_t *argv) {
 	printf("Debug mode activated\n");
 
-	debugState.seeking = kDebugSeekNothing;
-	debugState.runningStep = 0;
+	scriptState.seeking = kDebugSeekNothing;
+	scriptState.runningStep = 0;
 	return s->r_acc;
 }
 
diff --git a/engines/sci/engine/scriptdebug.cpp b/engines/sci/engine/scriptdebug.cpp
index d5f0a21385..9f69d21e2a 100644
--- a/engines/sci/engine/scriptdebug.cpp
+++ b/engines/sci/engine/scriptdebug.cpp
@@ -34,7 +34,7 @@ namespace Sci {
 
 extern const char *selector_name(EngineState *s, int selector);
 
-DebugState debugState;
+ScriptState scriptState;
 
 int propertyOffsetToId(EngineState *s, int prop_ofs, reg_t objp) {
 	Object *obj = obj_get(s, objp);
@@ -97,11 +97,6 @@ reg_t disassemble(EngineState *s, reg_t pos, int print_bw_tag, int print_bytecod
 	opsize = scr[pos.offset];
 	opcode = opsize >> 1;
 
-	if (!debugState.isValid) {
-		warning("Not in debug state");
-		return retval;
-	}
-
 	opsize &= 1; // byte if true, word if false
 
 	printf("%04x:%04x: ", PRINT_REG(pos));
@@ -226,11 +221,11 @@ reg_t disassemble(EngineState *s, reg_t pos, int print_bw_tag, int print_bytecod
 		}
 	}
 
-	if (pos == *debugState.p_pc) { // Extra information if debugging the current opcode
+	if (pos == scriptState.xs->addr.pc) { // Extra information if debugging the current opcode
 		if ((opcode == op_pTos) || (opcode == op_sTop) || (opcode == op_pToa) || (opcode == op_aTop) ||
 		        (opcode == op_dpToa) || (opcode == op_ipToa) || (opcode == op_dpTos) || (opcode == op_ipTos)) {
 			int prop_ofs = scr[pos.offset + 1];
-			int prop_id = propertyOffsetToId(s, prop_ofs, *debugState.p_objp);
+			int prop_id = propertyOffsetToId(s, prop_ofs, scriptState.xs->objp);
 
 			printf("	(%s)", selector_name(s, prop_id));
 		}
@@ -238,38 +233,38 @@ reg_t disassemble(EngineState *s, reg_t pos, int print_bw_tag, int print_bytecod
 
 	printf("\n");
 
-	if (pos == *debugState.p_pc) { // Extra information if debugging the current opcode
+	if (pos == scriptState.xs->addr.pc) { // Extra information if debugging the current opcode
 		if (opcode == op_callk) {
-			int stackframe = (scr[pos.offset + 2] >> 1) + (*debugState.p_restadjust);
-			int argc = ((*debugState.p_sp)[- stackframe - 1]).offset;
+			int stackframe = (scr[pos.offset + 2] >> 1) + (scriptState.restadjust);
+			int argc = ((scriptState.xs->sp)[- stackframe - 1]).offset;
 
 			if (!s->_kernel->hasOldScriptHeader())
-				argc += (*debugState.p_restadjust);
+				argc += (scriptState.restadjust);
 
 			printf(" Kernel params: (");
 
 			for (int j = 0; j < argc; j++) {
-				printf("%04x:%04x", PRINT_REG((*debugState.p_sp)[j - stackframe]));
+				printf("%04x:%04x", PRINT_REG((scriptState.xs->sp)[j - stackframe]));
 				if (j + 1 < argc)
 					printf(", ");
 			}
 			printf(")\n");
 		} else if ((opcode == op_send) || (opcode == op_self)) {
-			int restmod = *debugState.p_restadjust;
+			int restmod = scriptState.restadjust;
 			int stackframe = (scr[pos.offset + 1] >> 1) + restmod;
-			reg_t *sb = *debugState.p_sp;
+			reg_t *sb = scriptState.xs->sp;
 			uint16 selector;
 			reg_t fun_ref;
 
 			while (stackframe > 0) {
 				int argc = sb[- stackframe + 1].offset;
 				const char *name = NULL;
-				reg_t called_obj_addr = *debugState.p_objp;
+				reg_t called_obj_addr = scriptState.xs->objp;
 
 				if (opcode == op_send)
 					called_obj_addr = s->r_acc;
 				else if (opcode == op_self)
-					called_obj_addr = *debugState.p_objp;
+					called_obj_addr = scriptState.xs->objp;
 
 				selector = sb[- stackframe].offset;
 
@@ -313,45 +308,30 @@ reg_t disassemble(EngineState *s, reg_t pos, int print_bw_tag, int print_bytecod
 }
 
 
-void script_debug(EngineState *s, reg_t *pc, StackPtr *sp, StackPtr *pp, reg_t *objp, int *restadjust,
-	SegmentId *segids, reg_t **variables, reg_t **variables_base, int *variables_nr, int bp) {
+void script_debug(EngineState *s, bool bp) {
 	// Do we support a separate console?
 
-	bool old_debugstate = debugState.isValid;
-
-	debugState.p_var_segs = segids;
-	debugState.p_vars = variables;
-	debugState.p_var_max = variables_nr;
-	debugState.p_var_base = variables_base;
-	debugState.p_pc = pc;
-	debugState.p_sp = sp;
-	debugState.p_pp = pp;
-	debugState.p_objp = objp;
-	debugState.p_restadjust = restadjust;
 	printf("%d: acc=%04x:%04x  ", script_step_counter, PRINT_REG(s->r_acc));
-	debugState.isValid = true;
-	disassemble(s, *pc, 0, 1);
-	if (debugState.seeking == kDebugSeekGlobal)
-		printf("Global %d (0x%x) = %04x:%04x\n", debugState.seekSpecial,
-		          debugState.seekSpecial, PRINT_REG(s->script_000->locals_block->_locals[debugState.seekSpecial]));
-
-	debugState.isValid = old_debugstate;
+	disassemble(s, scriptState.xs->addr.pc, 0, 1);
+	if (scriptState.seeking == kDebugSeekGlobal)
+		printf("Global %d (0x%x) = %04x:%04x\n", scriptState.seekSpecial,
+		          scriptState.seekSpecial, PRINT_REG(s->script_000->locals_block->_locals[scriptState.seekSpecial]));
 
-	if (debugState.seeking && !bp) { // Are we looking for something special?
-		MemObject *mobj = GET_SEGMENT(*s->seg_manager, pc->segment, MEM_OBJ_SCRIPT);
+	if (scriptState.seeking && !bp) { // Are we looking for something special?
+		MemObject *mobj = GET_SEGMENT(*s->seg_manager, scriptState.xs->addr.pc.segment, MEM_OBJ_SCRIPT);
 
 		if (mobj) {
 			Script *scr = (Script *)mobj;
 			byte *code_buf = scr->buf;
 			int code_buf_size = scr->buf_size;
-			int opcode = pc->offset >= code_buf_size ? 0 : code_buf[pc->offset];
+			int opcode = scriptState.xs->addr.pc.offset >= code_buf_size ? 0 : code_buf[scriptState.xs->addr.pc.offset];
 			int op = opcode >> 1;
-			int paramb1 = pc->offset + 1 >= code_buf_size ? 0 : code_buf[pc->offset + 1];
-			int paramf1 = (opcode & 1) ? paramb1 : (pc->offset + 2 >= code_buf_size ? 0 : (int16)READ_LE_UINT16(code_buf + pc->offset + 1));
+			int paramb1 = scriptState.xs->addr.pc.offset + 1 >= code_buf_size ? 0 : code_buf[scriptState.xs->addr.pc.offset + 1];
+			int paramf1 = (opcode & 1) ? paramb1 : (scriptState.xs->addr.pc.offset + 2 >= code_buf_size ? 0 : (int16)READ_LE_UINT16(code_buf + scriptState.xs->addr.pc.offset + 1));
 
-			switch (debugState.seeking) {
+			switch (scriptState.seeking) {
 			case kDebugSeekSpecialCallk:
-				if (paramb1 != debugState.seekSpecial)
+				if (paramb1 != scriptState.seekSpecial)
 					return;
 
 			case kDebugSeekCallk: {
@@ -361,7 +341,7 @@ void script_debug(EngineState *s, reg_t *pc, StackPtr *sp, StackPtr *pp, reg_t *
 			}
 
 			case kDebugSeekLevelRet: {
-				if ((op != op_ret) || (debugState.seekLevel < (int)s->_executionStack.size()-1))
+				if ((op != op_ret) || (scriptState.seekLevel < (int)s->_executionStack.size()-1))
 					return;
 				break;
 			}
@@ -373,7 +353,7 @@ void script_debug(EngineState *s, reg_t *pc, StackPtr *sp, StackPtr *pp, reg_t *
 					return; // param or temp
 				if ((op & 0x3) && s->_executionStack.back().local_segment > 0)
 					return; // locals and not running in script.000
-				if (paramf1 != debugState.seekSpecial)
+				if (paramf1 != scriptState.seekSpecial)
 					return; // CORRECT global?
 				break;
 
@@ -382,32 +362,17 @@ void script_debug(EngineState *s, reg_t *pc, StackPtr *sp, StackPtr *pp, reg_t *
 				break;
 
 			case kDebugSeekNothing:
-				// FIXME: Unhandled?
+				// We seek nothing, so just continue
 				break;
 			}
 
-			debugState.seeking = kDebugSeekNothing;
+			scriptState.seeking = kDebugSeekNothing;
 			// OK, found whatever we were looking for
 		}
 	}
-
-	debugState.isValid = (debugState.runningStep == 0);
-
-	if (debugState.isValid) {
-		debugState.p_pc = pc;
-		debugState.p_sp = sp;
-		debugState.p_pp = pp;
-		debugState.p_objp = objp;
-		debugState.p_restadjust = restadjust;
-		debugState.p_var_segs = segids;
-		debugState.p_vars = variables;
-		debugState.p_var_max = variables_nr;
-		debugState.p_var_base = variables_base;
-		
-		printf("Step #%d\n", script_step_counter);
-		disassemble(s, *pc, 0, 1);
-	}
-
+	
+	printf("Step #%d\n", script_step_counter);
+	disassemble(s, scriptState.xs->addr.pc, 0, 1);
 }
 
 } // End of namespace Sci
diff --git a/engines/sci/engine/state.cpp b/engines/sci/engine/state.cpp
index e618077d54..c43fe9b6de 100644
--- a/engines/sci/engine/state.cpp
+++ b/engines/sci/engine/state.cpp
@@ -87,7 +87,7 @@ EngineState::EngineState(ResourceManager *res, sci_version_t version, uint32 fla
 	_executionStackPosChanged = false;
 
 	r_acc = NULL_REG;
-	r_amp_rest = 0;
+	restAdjust = 0;
 	r_prev = NULL_REG;
 
 	stack_segment = 0;
diff --git a/engines/sci/engine/state.h b/engines/sci/engine/state.h
index ecfb9fe6f7..92a5b5e411 100644
--- a/engines/sci/engine/state.h
+++ b/engines/sci/engine/state.h
@@ -208,7 +208,7 @@ public:
 	bool _executionStackPosChanged;   /**< Set to true if the execution stack position should be re-evaluated by the vm */
 
 	reg_t r_acc; /**< Accumulator */
-	unsigned int r_amp_rest; /**< &rest register (only used for save games) */
+	uint16 restAdjust; /**< &rest register (only used for save games) */
 	reg_t r_prev; /**< previous comparison result */
 
 	SegmentId stack_segment; /**< Heap area for the stack to use */
diff --git a/engines/sci/engine/vm.cpp b/engines/sci/engine/vm.cpp
index c6643b8a90..9bbdb90e0c 100644
--- a/engines/sci/engine/vm.cpp
+++ b/engines/sci/engine/vm.cpp
@@ -177,8 +177,8 @@ static void validate_write_var(reg_t *r, reg_t *stack_base, int type, int max, i
 
 #endif
 
-#define READ_VAR(type, index, def) validate_read_var(variables[type], s->stack_base, type, variables_max[type], index, __LINE__, def)
-#define WRITE_VAR(type, index, value) validate_write_var(variables[type], s->stack_base, type, variables_max[type], index, __LINE__, value)
+#define READ_VAR(type, index, def) validate_read_var(scriptState.variables[type], s->stack_base, type, scriptState.variables_max[type], index, __LINE__, def)
+#define WRITE_VAR(type, index, value) validate_write_var(scriptState.variables[type], s->stack_base, type, scriptState.variables_max[type], index, __LINE__, value)
 #define WRITE_VAR16(type, index, value) WRITE_VAR(type, index, make_reg(0, value));
 
 #define ACC_ARITHMETIC_L(op) make_reg(0, (op validate_arithmetic(s->r_acc)))
@@ -220,15 +220,15 @@ reg_t get_class_address(EngineState *s, int classnr, SCRIPT_GET lock, reg_t call
 #define PUSH(v) PUSH32(make_reg(0, v))
 #define POP() (validate_arithmetic(POP32()))
 // 32 bit:
-#define PUSH32(a) (*(validate_stack_addr(s, (xs->sp)++)) = (a))
-#define POP32() (*(validate_stack_addr(s, --(xs->sp))))
+#define PUSH32(a) (*(validate_stack_addr(s, (scriptState.xs->sp)++)) = (a))
+#define POP32() (*(validate_stack_addr(s, --(scriptState.xs->sp))))
 
 // Getting instruction parameters
-#define GET_OP_BYTE() ((uint8)code_buf[(xs->addr.pc.offset)++])
-#define GET_OP_WORD() (READ_LE_UINT16(code_buf + ((xs->addr.pc.offset) += 2) - 2))
+#define GET_OP_BYTE() ((uint8)code_buf[(scriptState.xs->addr.pc.offset)++])
+#define GET_OP_WORD() (READ_LE_UINT16(code_buf + ((scriptState.xs->addr.pc.offset) += 2) - 2))
 #define GET_OP_FLEX() ((opcode & 1)? GET_OP_BYTE() : GET_OP_WORD())
-#define GET_OP_SIGNED_BYTE() ((int8)(code_buf[(xs->addr.pc.offset)++]))
-#define GET_OP_SIGNED_WORD() (((int16)READ_LE_UINT16(code_buf + ((xs->addr.pc.offset) += 2) - 2)))
+#define GET_OP_SIGNED_BYTE() ((int8)(code_buf[(scriptState.xs->addr.pc.offset)++]))
+#define GET_OP_SIGNED_WORD() (((int16)READ_LE_UINT16(code_buf + ((scriptState.xs->addr.pc.offset) += 2) - 2)))
 #define GET_OP_SIGNED_FLEX() ((opcode & 1)? GET_OP_SIGNED_BYTE() : GET_OP_SIGNED_WORD())
 
 ExecStack *execute_method(EngineState *s, uint16 script, uint16 pubfunct, StackPtr sp, reg_t calling_obj, uint16 argc, StackPtr argp) {
@@ -388,7 +388,7 @@ ExecStack *send_selector(EngineState *s, reg_t send_obj, reg_t work_obj, StackPt
 				break;
 #ifdef STRICT_SEND
 			default:
-				debugState.seeking = debugState.runningStep = 0;
+				scriptState.seeking = scriptState.runningStep = 0;
 				error("Send error: Variable selector %04x in %04x:%04x called with %04x params", selector, PRINT_REG(send_obj), argc);
 #endif
 			}
@@ -543,11 +543,7 @@ static const byte _fake_return_buffer[2] = {op_ret << 1, op_ret << 1};
 void run_vm(EngineState *s, int restoring) {
 	assert(s);
 
-	reg_t *variables[4]; // global, local, temp, param, as immediate pointers
-	reg_t *variables_base[4]; // Used for referencing VM ops
-	SegmentId variables_seg[4]; // Same as above, contains segment IDs
 #ifndef DISABLE_VALIDATIONS
-	int variables_max[4]; // Max. values for all variables
 	unsigned int code_buf_size = 0 ; // (Avoid spurious warning)
 #endif
 	int temp;
@@ -556,13 +552,13 @@ void run_vm(EngineState *s, int restoring) {
 	StackPtr s_temp; // Temporary stack pointer
 	int16 opparams[4]; // opcode parameters
 
-	int restadjust = s->r_amp_rest;
+	scriptState.restadjust = s->restAdjust;
 	// &rest adjusts the parameter count by this value
 	// Current execution data:
-	ExecStack *xs = &(s->_executionStack.back());
+	scriptState.xs = &(s->_executionStack.back());
 	ExecStack *xs_new = NULL;
-	Object *obj = obj_get(s, xs->objp);
-	Script *local_script = script_locate_by_segment(s, xs->local_segment);
+	Object *obj = obj_get(s, scriptState.xs->objp);
+	Script *local_script = script_locate_by_segment(s, scriptState.xs->local_segment);
 	int old_execution_stack_base = s->execution_stack_base;
 	// Used to detect the stack bottom, for "physical" returns
 	const byte *code_buf = NULL; // (Avoid spurious warning)
@@ -577,22 +573,20 @@ void run_vm(EngineState *s, int restoring) {
 #ifndef DISABLE_VALIDATIONS
 	// Initialize maximum variable count
 	if (s->script_000->locals_block)
-		variables_max[VAR_GLOBAL] = s->script_000->locals_block->_locals.size();
+		scriptState.variables_max[VAR_GLOBAL] = s->script_000->locals_block->_locals.size();
 	else
-		variables_max[VAR_GLOBAL] = 0;
+		scriptState.variables_max[VAR_GLOBAL] = 0;
 #endif
 
-	variables_seg[VAR_GLOBAL] = s->script_000->locals_segment;
-	variables_seg[VAR_TEMP] = variables_seg[VAR_PARAM] = s->stack_segment;
-	variables_base[VAR_TEMP] = variables_base[VAR_PARAM] = s->stack_base;
+	scriptState.variables_seg[VAR_GLOBAL] = s->script_000->locals_segment;
+	scriptState.variables_seg[VAR_TEMP] = scriptState.variables_seg[VAR_PARAM] = s->stack_segment;
+	scriptState.variables_base[VAR_TEMP] = scriptState.variables_base[VAR_PARAM] = s->stack_base;
 
 	// SCI code reads the zeroeth argument to determine argc
 	if (s->script_000->locals_block)
-		variables_base[VAR_GLOBAL] = variables[VAR_GLOBAL] = s->script_000->locals_block->_locals.begin();
+		scriptState.variables_base[VAR_GLOBAL] = scriptState.variables[VAR_GLOBAL] = s->script_000->locals_block->_locals.begin();
 	else
-		variables_base[VAR_GLOBAL] = variables[VAR_GLOBAL] = NULL;
-
-
+		scriptState.variables_base[VAR_GLOBAL] = scriptState.variables[VAR_GLOBAL] = NULL;
 
 	s->_executionStackPosChanged = true; // Force initialization
 
@@ -602,58 +596,58 @@ void run_vm(EngineState *s, int restoring) {
 		int var_type; // See description below
 		int var_number;
 
-		debugState.old_pc_offset = xs->addr.pc.offset;
-		debugState.old_sp = xs->sp;
+		scriptState.old_pc_offset = scriptState.xs->addr.pc.offset;
+		scriptState.old_sp = scriptState.xs->sp;
 
 		if (s->_executionStackPosChanged) {
 			Script *scr;
-			xs = &(s->_executionStack.back());
+			scriptState.xs = &(s->_executionStack.back());
 			s->_executionStackPosChanged = false;
 
-			scr = script_locate_by_segment(s, xs->addr.pc.segment);
+			scr = script_locate_by_segment(s, scriptState.xs->addr.pc.segment);
 			if (!scr) {
 				// No script? Implicit return via fake instruction buffer
-				warning("Running on non-existant script in segment %x", xs->addr.pc.segment);
+				warning("Running on non-existant script in segment %x", scriptState.xs->addr.pc.segment);
 				code_buf = _fake_return_buffer;
 #ifndef DISABLE_VALIDATIONS
 				code_buf_size = 2;
 #endif
-				xs->addr.pc.offset = 1;
+				scriptState.xs->addr.pc.offset = 1;
 
 				scr = NULL;
 				obj = NULL;
 			} else {
-				obj = obj_get(s, xs->objp);
+				obj = obj_get(s, scriptState.xs->objp);
 				code_buf = scr->buf;
 #ifndef DISABLE_VALIDATIONS
 				code_buf_size = scr->buf_size;
 #endif
-				local_script = script_locate_by_segment(s, xs->local_segment);
+				local_script = script_locate_by_segment(s, scriptState.xs->local_segment);
 				if (!local_script) {
-					warning("Could not find local script from segment %x", xs->local_segment);
+					warning("Could not find local script from segment %x", scriptState.xs->local_segment);
 					local_script = NULL;
-					variables_base[VAR_LOCAL] = variables[VAR_LOCAL] = NULL;
+					scriptState.variables_base[VAR_LOCAL] = scriptState.variables[VAR_LOCAL] = NULL;
 #ifndef DISABLE_VALIDATIONS
-					variables_max[VAR_LOCAL] = 0;
+					scriptState.variables_max[VAR_LOCAL] = 0;
 #endif
 				} else {
 
-					variables_seg[VAR_LOCAL] = local_script->locals_segment;
+					scriptState.variables_seg[VAR_LOCAL] = local_script->locals_segment;
 					if (local_script->locals_block)
-						variables_base[VAR_LOCAL] = variables[VAR_LOCAL] = local_script->locals_block->_locals.begin();
+						scriptState.variables_base[VAR_LOCAL] = scriptState.variables[VAR_LOCAL] = local_script->locals_block->_locals.begin();
 					else
-						variables_base[VAR_LOCAL] = variables[VAR_LOCAL] = NULL;
+						scriptState.variables_base[VAR_LOCAL] = scriptState.variables[VAR_LOCAL] = NULL;
 #ifndef DISABLE_VALIDATIONS
 					if (local_script->locals_block)
-						variables_max[VAR_LOCAL] = local_script->locals_block->_locals.size();
+						scriptState.variables_max[VAR_LOCAL] = local_script->locals_block->_locals.size();
 					else
-						variables_max[VAR_LOCAL] = 0;
-					variables_max[VAR_TEMP] = xs->sp - xs->fp;
-					variables_max[VAR_PARAM] = xs->argc + 1;
+						scriptState.variables_max[VAR_LOCAL] = 0;
+					scriptState.variables_max[VAR_TEMP] = scriptState.xs->sp - scriptState.xs->fp;
+					scriptState.variables_max[VAR_PARAM] = scriptState.xs->argc + 1;
 #endif
 				}
-				variables[VAR_TEMP] = xs->fp;
-				variables[VAR_PARAM] = xs->variables_argp;
+				scriptState.variables[VAR_TEMP] = scriptState.xs->fp;
+				scriptState.variables[VAR_PARAM] = scriptState.xs->variables_argp;
 			}
 
 		}
@@ -665,24 +659,18 @@ void run_vm(EngineState *s, int restoring) {
 #if 0
 		// Debug if this has been requested:
 		if (script_debug_flag || sci_debug_flags) {
-			script_debug(s, &(xs->addr.pc), &(xs->sp), &(xs->fp), &(xs->objp), &restadjust, variables_seg, variables, variables_base,
-#ifdef DISABLE_VALIDATIONS
-			             NULL,
-#else
-			             variables_max,
-#endif
-			             breakpointFlag);
+			script_debug(s, breakpointFlag);
 			breakpointFlag = false;
 		}
 #endif
 
 #ifndef DISABLE_VALIDATIONS
-		if (xs->sp < xs->fp)
+		if (scriptState.xs->sp < scriptState.xs->fp)
 			error("run_vm(): stack underflow");
 
-		variables_max[VAR_TEMP] = xs->sp - xs->fp;
+		scriptState.variables_max[VAR_TEMP] = scriptState.xs->sp - scriptState.xs->fp;
 
-		if (xs->addr.pc.offset >= code_buf_size)
+		if (scriptState.xs->addr.pc.offset >= code_buf_size)
 			error("run_vm(): program counter gone astray");
 #endif
 
@@ -900,16 +888,16 @@ void run_vm(EngineState *s, int restoring) {
 
 		case 0x17: // bt
 			if (s->r_acc.offset || s->r_acc.segment)
-				xs->addr.pc.offset += opparams[0];
+				scriptState.xs->addr.pc.offset += opparams[0];
 			break;
 
 		case 0x18: // bnt
 			if (!(s->r_acc.offset || s->r_acc.segment))
-				xs->addr.pc.offset += opparams[0];
+				scriptState.xs->addr.pc.offset += opparams[0];
 			break;
 
 		case 0x19: // jmp
-			xs->addr.pc.offset += opparams[0];
+			scriptState.xs->addr.pc.offset += opparams[0];
 			break;
 
 		case 0x1a: // ldi
@@ -925,33 +913,36 @@ void run_vm(EngineState *s, int restoring) {
 			break;
 
 		case 0x1d: // toss
-			xs->sp--;
+			scriptState.xs->sp--;
 			break;
 
 		case 0x1e: // dup
-			r_temp = xs->sp[-1];
+			r_temp = scriptState.xs->sp[-1];
 			PUSH32(r_temp);
 			break;
 
 		case 0x1f: { // link
 			int i;
 			for (i = 0; i < opparams[0]; i++)
-				xs->sp[i] = NULL_REG;
-			xs->sp += opparams[0];
+				scriptState.xs->sp[i] = NULL_REG;
+			scriptState.xs->sp += opparams[0];
 			break;
 		}
 
 		case 0x20: { // call
 			int argc = (opparams[1] >> 1) // Given as offset, but we need count
-			           + 1 + restadjust;
-			StackPtr call_base = xs->sp - argc;
-			xs->sp[1].offset += restadjust;
-
-			xs_new = add_exec_stack_entry(s, make_reg(xs->addr.pc.segment, xs->addr.pc.offset + opparams[0]),
-			                              xs->sp, xs->objp, (validate_arithmetic(*call_base)) + restadjust,
-			                              call_base, NULL_SELECTOR, xs->objp, s->_executionStack.size()-1, xs->local_segment);
-			restadjust = 0; // Used up the &rest adjustment
-			xs->sp = call_base;
+			           + 1 + scriptState.restadjust;
+			StackPtr call_base = scriptState.xs->sp - argc;
+			scriptState.xs->sp[1].offset += scriptState.restadjust;
+
+			xs_new = add_exec_stack_entry(s, make_reg(scriptState.xs->addr.pc.segment, 
+										  scriptState.xs->addr.pc.offset + opparams[0]),
+			                              scriptState.xs->sp, scriptState.xs->objp,
+										  (validate_arithmetic(*call_base)) + scriptState.restadjust,
+			                              call_base, NULL_SELECTOR, scriptState.xs->objp, 
+										  s->_executionStack.size()-1, scriptState.xs->local_segment);
+			scriptState.restadjust = 0; // Used up the &rest adjustment
+			scriptState.xs->sp = call_base;
 
 			s->_executionStackPosChanged = true;
 			break;
@@ -960,25 +951,28 @@ void run_vm(EngineState *s, int restoring) {
 		case 0x21: // callk
 			gc_countdown(s);
 
-			xs->sp -= (opparams[1] >> 1) + 1;
+			scriptState.xs->sp -= (opparams[1] >> 1) + 1;
 			if (!s->_kernel->hasOldScriptHeader()) {
-				xs->sp -= restadjust;
-				s->r_amp_rest = 0; // We just used up the restadjust, remember?
+				scriptState.xs->sp -= scriptState.restadjust;
+				s->restAdjust = 0; // We just used up the restadjust, remember?
 			}
 
 			if (opparams[0] >= (int)s->_kernel->_kernelFuncs.size()) {
 				error("Invalid kernel function 0x%x requested\n", opparams[0]);
 			} else {
-				int argc = ASSERT_ARITHMETIC(xs->sp[0]);
+				int argc = ASSERT_ARITHMETIC(scriptState.xs->sp[0]);
 
 				if (!s->_kernel->hasOldScriptHeader())
-					argc += restadjust;
+					argc += scriptState.restadjust;
 
 				if (s->_kernel->_kernelFuncs[opparams[0]].signature
-				        && !kernel_matches_signature(s, s->_kernel->_kernelFuncs[opparams[0]].signature, argc, xs->sp + 1)) {
+				        && !kernel_matches_signature(s, 
+							s->_kernel->_kernelFuncs[opparams[0]].signature, argc, 
+							scriptState.xs->sp + 1)) {
 					error("[VM] Invalid arguments to kernel call %x\n", opparams[0]);
 				} else {
-					s->r_acc = s->_kernel->_kernelFuncs[opparams[0]].fun(s, opparams[0], argc, xs->sp + 1);
+					s->r_acc = s->_kernel->_kernelFuncs[opparams[0]].fun(s, opparams[0], 
+														argc, scriptState.xs->sp + 1);
 				}
 				// Call kernel function
 
@@ -989,31 +983,33 @@ void run_vm(EngineState *s, int restoring) {
 				s->_executionStackPosChanged = true;
 
 				if (!s->_kernel->hasOldScriptHeader())
-					restadjust = s->r_amp_rest;
+					scriptState.restadjust = s->restAdjust;
 
 			}
 			break;
 
 		case 0x22: // callb
-			temp = ((opparams[1] >> 1) + restadjust + 1);
-			s_temp = xs->sp;
-			xs->sp -= temp;
-
-			xs->sp[0].offset += restadjust;
-			xs_new = execute_method(s, 0, opparams[0], s_temp, xs->objp, xs->sp[0].offset, xs->sp);
-			restadjust = 0; // Used up the &rest adjustment
+			temp = ((opparams[1] >> 1) + scriptState.restadjust + 1);
+			s_temp = scriptState.xs->sp;
+			scriptState.xs->sp -= temp;
+
+			scriptState.xs->sp[0].offset += scriptState.restadjust;
+			xs_new = execute_method(s, 0, opparams[0], s_temp, scriptState.xs->objp, 
+									scriptState.xs->sp[0].offset, scriptState.xs->sp);
+			scriptState.restadjust = 0; // Used up the &rest adjustment
 			if (xs_new)    // in case of error, keep old stack
 				s->_executionStackPosChanged = true;
 			break;
 
 		case 0x23: // calle
-			temp = ((opparams[2] >> 1) + restadjust + 1);
-			s_temp = xs->sp;
-			xs->sp -= temp;
+			temp = ((opparams[2] >> 1) + scriptState.restadjust + 1);
+			s_temp = scriptState.xs->sp;
+			scriptState.xs->sp -= temp;
 
-			xs->sp[0].offset += restadjust;
-			xs_new = execute_method(s, opparams[0], opparams[1], s_temp, xs->objp, xs->sp[0].offset, xs->sp);
-			restadjust = 0; // Used up the &rest adjustment
+			scriptState.xs->sp[0].offset += scriptState.restadjust;
+			xs_new = execute_method(s, opparams[0], opparams[1], s_temp, scriptState.xs->objp, 
+									scriptState.xs->sp[0].offset, scriptState.xs->sp);
+			scriptState.restadjust = 0; // Used up the &rest adjustment
 
 			if (xs_new)  // in case of error, keep old stack
 				s->_executionStackPosChanged = true;
@@ -1021,8 +1017,8 @@ void run_vm(EngineState *s, int restoring) {
 
 		case 0x24: // ret
 			do {
-				StackPtr old_sp2 = xs->sp;
-				StackPtr old_fp = xs->fp;
+				StackPtr old_sp2 = scriptState.xs->sp;
+				StackPtr old_fp = scriptState.xs->fp;
 				ExecStack *old_xs = &(s->_executionStack.back());
 
 				if ((int)s->_executionStack.size()-1 == s->execution_stack_base) { // Have we reached the base?
@@ -1031,7 +1027,7 @@ void run_vm(EngineState *s, int restoring) {
 					s->_executionStack.pop_back();
 
 					s->_executionStackPosChanged = true;
-					s->r_amp_rest = restadjust; // Update &rest
+					s->restAdjust = scriptState.restadjust; // Update &rest
 					return; // "Hard" return
 				}
 
@@ -1046,80 +1042,84 @@ void run_vm(EngineState *s, int restoring) {
 				// Not reached the base, so let's do a soft return
 				s->_executionStack.pop_back();
 				s->_executionStackPosChanged = true;
-				xs = &(s->_executionStack.back());
+				scriptState.xs = &(s->_executionStack.back());
 
-				if (xs->sp == CALL_SP_CARRY // Used in sends to 'carry' the stack pointer
-				        || xs->type != EXEC_STACK_TYPE_CALL) {
-					xs->sp = old_sp2;
-					xs->fp = old_fp;
+				if (scriptState.xs->sp == CALL_SP_CARRY // Used in sends to 'carry' the stack pointer
+				        || scriptState.xs->type != EXEC_STACK_TYPE_CALL) {
+					scriptState.xs->sp = old_sp2;
+					scriptState.xs->fp = old_fp;
 				}
 
-			} while (xs->type == EXEC_STACK_TYPE_VARSELECTOR);
+			} while (scriptState.xs->type == EXEC_STACK_TYPE_VARSELECTOR);
 			// Iterate over all varselector accesses
 			s->_executionStackPosChanged = true;
-			xs_new = xs;
+			xs_new = scriptState.xs;
 
 			break;
 
 		case 0x25: // send
-			s_temp = xs->sp;
-			xs->sp -= ((opparams[0] >> 1) + restadjust); // Adjust stack
+			s_temp = scriptState.xs->sp;
+			scriptState.xs->sp -= ((opparams[0] >> 1) + scriptState.restadjust); // Adjust stack
 
-			xs->sp[1].offset += restadjust;
-			xs_new = send_selector(s, s->r_acc, s->r_acc, s_temp, (int)(opparams[0] >> 1) + (uint16)restadjust, xs->sp);
+			scriptState.xs->sp[1].offset += scriptState.restadjust;
+			xs_new = send_selector(s, s->r_acc, s->r_acc, s_temp, 
+					(int)(opparams[0] >> 1) + scriptState.restadjust, scriptState.xs->sp);
 
-			if (xs_new && xs_new != xs)
+			if (xs_new && xs_new != scriptState.xs)
 				s->_executionStackPosChanged = true;
 
-			restadjust = 0;
+			scriptState.restadjust = 0;
 
 			break;
 
 		case 0x28: // class
-			s->r_acc = get_class_address(s, (unsigned)opparams[0], SCRIPT_GET_LOCK, xs->addr.pc);
+			s->r_acc = get_class_address(s, (unsigned)opparams[0], SCRIPT_GET_LOCK, 
+											scriptState.xs->addr.pc);
 			break;
 
 		case 0x2a: // self
-			s_temp = xs->sp;
-			xs->sp -= ((opparams[0] >> 1) + restadjust); // Adjust stack
+			s_temp = scriptState.xs->sp;
+			scriptState.xs->sp -= ((opparams[0] >> 1) + scriptState.restadjust); // Adjust stack
 
-			xs->sp[1].offset += restadjust;
-			xs_new = send_selector(s, xs->objp, xs->objp, s_temp, (int)(opparams[0] >> 1) + (uint16)restadjust, xs->sp);
+			scriptState.xs->sp[1].offset += scriptState.restadjust;
+			xs_new = send_selector(s, scriptState.xs->objp, scriptState.xs->objp, 
+									s_temp, (int)(opparams[0] >> 1) + scriptState.restadjust, 
+									scriptState.xs->sp);
 
-			if (xs_new && xs_new != xs)
+			if (xs_new && xs_new != scriptState.xs)
 				s->_executionStackPosChanged = true;
 
-			restadjust = 0;
+			scriptState.restadjust = 0;
 			break;
 
 		case 0x2b: // super
-			r_temp = get_class_address(s, opparams[0], SCRIPT_GET_LOAD, xs->addr.pc);
+			r_temp = get_class_address(s, opparams[0], SCRIPT_GET_LOAD, scriptState.xs->addr.pc);
 
 			if (!r_temp.segment)
 				error("[VM]: Invalid superclass in object");
 			else {
-				s_temp = xs->sp;
-				xs->sp -= ((opparams[1] >> 1) + restadjust); // Adjust stack
+				s_temp = scriptState.xs->sp;
+				scriptState.xs->sp -= ((opparams[1] >> 1) + scriptState.restadjust); // Adjust stack
 
-				xs->sp[1].offset += restadjust;
-				xs_new = send_selector(s, r_temp, xs->objp, s_temp, (int)(opparams[1] >> 1) + (uint16)restadjust, xs->sp);
+				scriptState.xs->sp[1].offset += scriptState.restadjust;
+				xs_new = send_selector(s, r_temp, scriptState.xs->objp, s_temp, 
+										(int)(opparams[1] >> 1) + scriptState.restadjust, 
+										scriptState.xs->sp);
 
-				if (xs_new && xs_new != xs)
+				if (xs_new && xs_new != scriptState.xs)
 					s->_executionStackPosChanged = true;
 
-				restadjust = 0;
+				scriptState.restadjust = 0;
 			}
 
 			break;
 
 		case 0x2c: // &rest
 			temp = (uint16) opparams[0]; // First argument
-			restadjust = xs->argc - temp + 1; // +1 because temp counts the paramcount while argc doesn't
-			if (restadjust < 0)
-				restadjust = 0;
+			scriptState.restadjust = MAX<uint16>(scriptState.xs->argc - temp + 1, 0); // +1 because temp counts the paramcount while argc doesn't
 
-			for (; temp <= xs->argc; temp++)
-				PUSH32(xs->variables_argp[temp]);
+			for (; temp <= scriptState.xs->argc; temp++)
+				PUSH32(scriptState.xs->variables_argp[temp]);
 
 			break;
 
@@ -1128,8 +1128,8 @@ void run_vm(EngineState *s, int restoring) {
 			var_number = temp & 0x03; // Get variable type
 
 			// Get variable block offset
-			r_temp.segment = variables_seg[var_number];
-			r_temp.offset = variables[var_number] - variables_base[var_number];
+			r_temp.segment = scriptState.variables_seg[var_number];
+			r_temp.offset = scriptState.variables[var_number] - scriptState.variables_base[var_number];
 
 			if (temp & 0x08)  // Add accumulator offset if requested
 				r_temp.offset += signed_validate_arithmetic(s->r_acc);
@@ -1142,7 +1142,7 @@ void run_vm(EngineState *s, int restoring) {
 
 
 		case 0x2e: // selfID
-			s->r_acc = xs->objp;
+			s->r_acc = scriptState.xs->objp;
 			break;
 
 		case 0x30: // pprev
@@ -1189,7 +1189,7 @@ void run_vm(EngineState *s, int restoring) {
 
 
 		case 0x39: // lofsa
-			s->r_acc.segment = xs->addr.pc.segment;
+			s->r_acc.segment = scriptState.xs->addr.pc.segment;
 
 			if (s->_version >= SCI_VERSION_1_1) {
 				s->r_acc.offset = opparams[0] + local_script->script_size;
@@ -1197,7 +1197,7 @@ void run_vm(EngineState *s, int restoring) {
 				if (s->_kernel->hasLofsAbsolute())
 					s->r_acc.offset = opparams[0];
 				else
-					s->r_acc.offset = xs->addr.pc.offset + opparams[0];
+					s->r_acc.offset = scriptState.xs->addr.pc.offset + opparams[0];
 			}
 
 #ifndef DISABLE_VALIDATIONS
@@ -1209,7 +1209,7 @@ void run_vm(EngineState *s, int restoring) {
 			break;
 
 		case 0x3a: // lofss
-			r_temp.segment = xs->addr.pc.segment;
+			r_temp.segment = scriptState.xs->addr.pc.segment;
 
 			if (s->_version >= SCI_VERSION_1_1) {
 				r_temp.offset = opparams[0] + local_script->script_size;
@@ -1217,7 +1217,7 @@ void run_vm(EngineState *s, int restoring) {
 				if (s->_kernel->hasLofsAbsolute())
 					r_temp.offset = opparams[0];
 				else
-					r_temp.offset = xs->addr.pc.offset + opparams[0];
+					r_temp.offset = scriptState.xs->addr.pc.offset + opparams[0];
 			}
 
 #ifndef DISABLE_VALIDATIONS
@@ -1242,7 +1242,7 @@ void run_vm(EngineState *s, int restoring) {
 			break;
 
 		case 0x3e: // pushSelf
-			PUSH32(xs->objp);
+			PUSH32(scriptState.xs->objp);
 			break;
 
 		case 0x40: // lag
@@ -1410,12 +1410,12 @@ void run_vm(EngineState *s, int restoring) {
 		} // switch(opcode >> 1)
 
 		if (s->_executionStackPosChanged) // Force initialization
-			xs = xs_new;
+			scriptState.xs = xs_new;
 
 //#ifndef DISABLE_VALIDATIONS
-		if (xs != &(s->_executionStack.back())) {
+		if (scriptState.xs != &(s->_executionStack.back())) {
 			warning("xs is stale (%p vs %p); last command was %02x",
-					(void *)xs, (void *)&(s->_executionStack.back()),
+					(void *)scriptState.xs, (void *)&(s->_executionStack.back()),
 					opnumber);
 		}
 //#endif
@@ -2037,9 +2037,8 @@ const char *obj_get_name(EngineState *s, reg_t pos) {
 
 void quit_vm() {
 	script_abort_flag = 1; // Terminate VM
-	debugState.isValid = false;
-	debugState.seeking = kDebugSeekNothing;
-	debugState.runningStep = 0;
+	scriptState.seeking = kDebugSeekNothing;
+	scriptState.runningStep = 0;
 }
 
 void shrink_execution_stack(EngineState *s, uint size) {
diff --git a/engines/sci/engine/vm.h b/engines/sci/engine/vm.h
index a3fabbe44b..1472fae97c 100644
--- a/engines/sci/engine/vm.h
+++ b/engines/sci/engine/vm.h
@@ -243,24 +243,23 @@ enum ExecStackType {
 };
 
 struct ExecStack {
-	reg_t objp;
-	reg_t sendp; /**< Pointer to the object containing the invoked method */
+	reg_t objp;  // Pointer to the beginning of the current object
+	reg_t sendp; // Pointer to the object containing the invoked method
 
 	union {
-		ObjVarRef varp; /**< Variable pointer for r/w access */
-		reg_t pc; /**< Not accurate for the TOS element */
+		ObjVarRef varp; // Variable pointer for r/w access
+		reg_t pc;       // Pointer to the initial program counter. Not accurate for the TOS element
 	} addr;
 
-	StackPtr fp; /**< Frame pointer */
-	StackPtr sp; /**< Stack pointer */
+	StackPtr fp; // Frame pointer
+	StackPtr sp; // Stack pointer
 	int argc;
 
-	/* former variables[4]: [all other values are derived] */
-	StackPtr variables_argp; /**< Argument pointer */
-	SegmentId local_segment; /**< local variables etc. */
+	StackPtr variables_argp; // Argument pointer
+	SegmentId local_segment; // local variables etc
 
-	Selector selector; /**< The selector which was used to call or -1 if not applicable */
-	int origin;   /**< The stack frame position the call was made from, or -1 if it was the initial call.  */
+	Selector selector;      // The selector which was used to call or -1 if not applicable
+	int origin;             // The stack frame position the call was made from, or -1 if it was the initial call
 	ExecStackType type;
 
 	reg_t* getVarPointer(EngineState *s) const;
@@ -409,27 +408,10 @@ void vm_handle_fatal_error(EngineState *s, int line, const char *file);
 
 /**
  * Debugger functionality
- * @param[in] s					The state at which debugging should take
- * 								place
- * @param[in] pc				Pointer to the program counter
- * @param[in] sp				Pointer to the stack pointer
- * @param[in] pp				Pointer to the frame pointer
- * @param[in] objp				Pointer to the object base pointer
- * @param[in] restadjust		Pointer to the &rest adjustment value
- * @param[in] segids			four-element array containing segment IDs
- * 								for locals etc.
- * @param[in] variables			four-element array referencing registers
- * 								for globals etc.
- * @param[in] variables_base	four-element array referencing register 
- * 								bases for temps etc.
- * @param[in] variables_nr		four-element array giving sizes for params
- * 								etc. (may be NULL)
- * @param[in] bp				Flag, set to 1 when a breakpoint is
- * 								triggered
- */
-void script_debug(EngineState *s, reg_t *pc, StackPtr *sp, StackPtr *pp, 
-		reg_t *objp, int *restadjust, SegmentId *segids, reg_t **variables,
-		reg_t **variables_base, int *variables_nr, int bp);
+ * @param[in] s					The state at which debugging should take place
+ * @param[in] bp				Flag, set to true when a breakpoint is triggered
+ */
+void script_debug(EngineState *s, bool bp);
 
 /**
  * Initializes a EngineState block