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engines/tony/mpal/expr.h

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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/>.
+ *
+ */
+/*
+ * This code is based on original Tony Tough source code
+ *
+ * Copyright (c) 1997-2003 Nayma Software
+ */
+
+#ifndef MPAL_EXPR_H
+#define MPAL_EXPR_H
+
+#include "tony/mpal/memory.h"
+
+namespace Tony {
+
+namespace MPAL {
+
+/**
+ * @defgroup Mathematical operations
+ */
+//@{
+
+#define OP_MUL     ((1  << 4) | 0)
+#define OP_DIV     ((1  << 4) | 1)
+#define OP_MODULE  ((1  << 4) | 2)
+#define OP_ADD     ((2  << 4) | 0)
+#define OP_SUB     ((2  << 4) | 1)
+#define OP_SHL     ((3  << 4) | 0)
+#define OP_SHR     ((3  << 4) | 1)
+#define OP_MINOR   ((4  << 4) | 0)
+#define OP_MAJOR   ((4  << 4) | 1)
+#define OP_MINEQ   ((4  << 4) | 2)
+#define OP_MAJEQ   ((4  << 4) | 3)
+#define OP_EQUAL   ((5  << 4) | 0)
+#define OP_NOEQUAL ((5  << 4) | 1)
+#define OP_BITAND  ((6  << 4) | 0)
+#define OP_BITXOR  ((7  << 4) | 0)
+#define OP_BITOR   ((8  << 4) | 0)
+#define OP_AND     ((9  << 4) | 0)
+#define OP_OR      ((10 << 4) | 0)
+
+//@}
+
+/**
+ * @defgroup Structures
+ */
+
+//@{
+/**
+ * Mathematical framework to manage operations
+ */
+typedef struct {
+	byte _type;          // Object Type (see enum ExprListTypes)
+
+	union {
+		int32 _num;      // Identifier (if type == ELT_NUMBER)
+		char *_name;     // Variable name (if type == ELT_VAR)
+		MpalHandle _son; // Handle expressions (if type == ELT_PARENTH)
+		void *_pson;     // Handle lockato (if type == ELT_PARENTH2)
+	} _val;
+
+	byte _symbol;        // Mathematic symbols (see #define OP_*)
+
+} Expression;
+typedef Expression *LpExpression;
+
+//@}
+
+/**
+ * Object types that can be contained in an EXPRESSION structure
+ */
+enum ExprListTypes {
+	ELT_NUMBER   = 1,
+	ELT_VAR      = 2,
+	ELT_PARENTH  = 3,
+	ELT_PARENTH2 = 4
+};
+
+/****************************************************************************\
+*       Function Prototypes
+\****************************************************************************/
+
+/**
+ * Parses a mathematical expression from the MPC file
+ *
+ * @param buf				Buffer containing the expression to evaluate
+ * @param h					Pointer to a handle that, at the end of execution,
+ * will point to the area of memory containing the parsed expression
+ * @returns		Pointer to the buffer immediately after the expression, or NULL if error.
+ */
+const byte *parseExpression(const byte *lpBuf, const Common::UnalignedPtr<MpalHandle> &h);
+
+/**
+ * Calculate the value of a mathematical expression
+ *
+ * @param h					Handle to the expression
+ * @returns		Numeric value
+ */
+int32 evaluateExpression(MpalHandle h);
+
+/**
+ * Compare two mathematical expressions together
+ *
+ * @param h1				Expression to be compared
+ * @param h2				Expression to be compared
+ */
+bool compareExpressions(MpalHandle h1, MpalHandle h2);
+
+/**
+ * Frees an expression that was previously parsed
+ *
+ * @param h					Handle for the expression
+ */
+void freeExpression(MpalHandle h);
+
+} // end of namespace MPAL
+
+} // end of namespace Tony
+
+#endif