Initial commit

engines/glk/alan3/state_stack.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "glk/alan3/state_stack.h"
+#include "glk/alan3/syserr.h"
+#include "glk/alan3/memory.h"
+#include "glk/alan3/state.h"
+
+namespace Glk {
+namespace Alan3 {
+
+/* CONSTANTS: */
+#define EXTENT 10
+
+
+/* PRIVATE TYPES: */
+struct StateStackStructure {
+	void **states;
+	char **commands;
+	int stackSize;
+	int stackPointer;   /* Points above used stack, 0 initially */
+	int elementSize;    /* Size of elements in the stack */
+};
+
+
+/*----------------------------------------------------------------------*/
+static void *reallocate(void *from, int newSize) {
+	void *newArea = realloc(from, newSize * sizeof(void *));
+	if (newArea == nullptr)
+		syserr("Out of memory in 'reallocateStack()'");
+	return newArea;
+}
+
+/*======================================================================*/
+StateStackP createStateStack(int elementSize) {
+	StateStackP stack = NEW(StateStackStructure);
+	stack->stackSize = 0;
+	stack->stackPointer = 0;
+	stack->elementSize = elementSize;
+	return stack;
+}
+
+
+/*======================================================================*/
+void deleteStateStack(StateStackP stateStack) {
+	if (stateStack != nullptr) {
+		while (stateStack->stackPointer > 0) {
+			stateStack->stackPointer--;
+			deallocateGameState((GameState *)stateStack->states[stateStack->stackPointer]);
+			deallocate(stateStack->states[stateStack->stackPointer]);
+			deallocate(stateStack->commands[stateStack->stackPointer]);
+		}
+		if (stateStack->stackSize > 0) {
+			deallocate(stateStack->states);
+			deallocate(stateStack->commands);
+		}
+		deallocate(stateStack);
+	}
+}
+
+
+/*======================================================================*/
+bool stateStackIsEmpty(StateStackP stateStack) {
+	return stateStack->stackPointer == 0;
+}
+
+
+/*----------------------------------------------------------------------*/
+static void ensureSpaceForGameState(StateStackP stack) {
+	if (stack->stackPointer == stack->stackSize) {
+		stack->states = (void **)reallocate(stack->states, stack->stackSize + EXTENT);
+		stack->commands = (char **)reallocate(stack->commands, stack->stackSize + EXTENT);
+		stack->stackSize += EXTENT;
+	}
+}
+
+
+/*======================================================================*/
+void pushGameState(StateStackP stateStack, void *gameState) {
+	void *element = allocate(stateStack->elementSize);
+	memcpy(element, gameState, stateStack->elementSize);
+	ensureSpaceForGameState(stateStack);
+	stateStack->commands[stateStack->stackPointer] = nullptr;
+	stateStack->states[stateStack->stackPointer++] = element;
+}
+
+
+/*======================================================================*/
+void attachPlayerCommandsToLastState(StateStackP stateStack, char *playerCommands) {
+	stateStack->commands[stateStack->stackPointer - 1] = scumm_strdup(playerCommands);
+}
+
+
+/*======================================================================*/
+void popGameState(StateStackP stateStack, void *gameState, char **playerCommand) {
+	if (stateStack->stackPointer == 0)
+		syserr("Popping GameState from empty stack");
+	else {
+		stateStack->stackPointer--;
+		memcpy(gameState, stateStack->states[stateStack->stackPointer], stateStack->elementSize);
+		deallocate(stateStack->states[stateStack->stackPointer]);
+		*playerCommand = stateStack->commands[stateStack->stackPointer];
+	}
+}
+
+} // End of namespace Alan3
+} // End of namespace Glk