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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 2
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#include "common/debug.h"
#include "common/stream.h"
#include "common/stack.h"
#include "draci/script.h"
#include "draci/draci.h"
namespace Draci {
// FIXME: Change parameter types to names once I figure out what they are exactly
/** A table of all the commands the game player uses */
GPL2Command gplCommands[] = {
{ 0, 0, "gplend", 0, { 0 } },
{ 0, 1, "exit", 0, { 0 } },
{ 1, 1, "goto", 1, { 3 } },
{ 2, 1, "Let", 2, { 3, 4 } },
{ 3, 1, "if", 2, { 4, 3 } },
{ 4, 1, "Start", 2, { 3, 2 } },
{ 5, 1, "Load", 2, { 3, 2 } },
{ 5, 2, "StartPlay", 2, { 3, 2 } },
{ 5, 3, "JustTalk", 0, { 0 } },
{ 5, 4, "JustStay", 0, { 0 } },
{ 6, 1, "Talk", 2, { 3, 2 } },
{ 7, 1, "ObjStat", 2, { 3, 3 } },
{ 7, 2, "ObjStat_On", 2, { 3, 3 } },
{ 8, 1, "IcoStat", 2, { 3, 3 } },
{ 9, 1, "Dialogue", 1, { 2 } },
{ 9, 2, "ExitDialogue", 0, { 0 } },
{ 9, 3, "ResetDialogue", 0, { 0 } },
{ 9, 4, "ResetDialogueFrom", 0, { 0 } },
{ 9, 5, "ResetBlock", 1, { 3 } },
{ 10, 1, "WalkOn", 3, { 1, 1, 3 } },
{ 10, 2, "StayOn", 3, { 1, 1, 3 } },
{ 10, 3, "WalkOnPlay", 3, { 1, 1, 3 } },
{ 11, 1, "LoadPalette", 1, { 2 } },
{ 12, 1, "SetPalette", 0, { 0 } },
{ 12, 2, "BlackPalette", 0, { 0 } },
{ 13, 1, "FadePalette", 3, { 1, 1, 1 } },
{ 13, 2, "FadePalettePlay", 3, { 1, 1, 1 } },
{ 14, 1, "NewRoom", 2, { 3, 1 } },
{ 15, 1, "ExecInit", 1, { 3 } },
{ 15, 2, "ExecLook", 1, { 3 } },
{ 15, 3, "ExecUse", 1, { 3 } },
{ 16, 1, "RepaintInventory", 0, { 0 } },
{ 16, 2, "ExitInventory", 0, { 0 } },
{ 17, 1, "ExitMap", 0, { 0 } },
{ 18, 1, "LoadMusic", 1, { 2 } },
{ 18, 2, "StartMusic", 0, { 0 } },
{ 18, 3, "StopMusic", 0, { 0 } },
{ 18, 4, "FadeOutMusic", 1, { 1 } },
{ 18, 5, "FadeInMusic", 1, { 1 } },
{ 19, 1, "Mark", 0, { 0 } },
{ 19, 2, "Release", 0, { 0 } },
{ 20, 1, "Play", 0, { 0 } },
{ 21, 1, "LoadMap", 1, { 2 } },
{ 21, 2, "RoomMap", 0, { 0 } },
{ 22, 1, "DisableQuickHero", 0, { 0 } },
{ 22, 2, "EnableQuickHero", 0, { 0 } },
{ 23, 1, "DisableSpeedText", 0, { 0 } },
{ 23, 2, "EnableSpeedText", 0, { 0 } },
{ 24, 1, "QuitGame", 0, { 0 } },
{ 25, 1, "PushNewRoom", 0, { 0 } },
{ 25, 2, "PopNewRoom", 0, { 0 } },
{ 26, 1, "ShowCheat", 0, { 0 } },
{ 26, 2, "HideCheat", 0, { 0 } },
{ 26, 3, "ClearCheat", 1, { 1 } },
{ 27, 1, "FeedPassword", 3, { 1, 1, 1 } }
};
/** Operators used by the mathematical evaluator */
Common::String operators[] = {
"oper_and",
"oper_or",
"oper_xor",
"oper_equals",
"oper_not_equal",
"oper_less_than",
"oper_greater_than",
"oper_less_or_equal",
"oper_greater_or_equal",
"oper_multiply",
"oper_divide",
"oper_remainder",
"oper_plus",
"oper_minus"
};
/** Functions used by the mathematical evaluator */
Common::String functions[] = {
"F_Not",
"F_Random",
"F_IsIcoOn",
"F_IsIcoAct",
"F_IcoStat",
"F_ActIco",
"F_IsObjOn",
"F_IsObjOff",
"F_IsObjAway",
"F_ObjStat",
"F_LastBlock",
"F_AtBegin",
"F_BlockVar",
"F_HasBeen",
"F_MaxLine",
"F_ActPhase",
"F_Cheat"
};
const unsigned int kNumCommands = sizeof gplCommands / sizeof gplCommands[0];
/** Type of mathematical object */
enum mathExpressionObject {
kMathEnd,
kMathNumber,
kMathOperator,
kMathFunctionCall,
kMathVariable
};
// FIXME: The evaluator is now complete but I still need to implement callbacks
/**
* @brief Evaluates mathematical expressions
* @param reader Stream reader set to the beginning of the expression
*/
void Script::handleMathExpression(Common::MemoryReadStream &reader) {
Common::Stack<uint16> stk;
mathExpressionObject obj;
// Read in initial math object
obj = (mathExpressionObject)reader.readUint16LE();
uint16 value;
while (1) {
if (obj == kMathEnd) {
// Check whether the expression was evaluated correctly
// The stack should contain only one value after the evaluation
// i.e. the result of the expression
assert(stk.size() == 1 && "Mathematical expression error");
break;
}
switch (obj) {
// If the object type is not known, assume that it's a number
default:
case kMathNumber:
value = reader.readUint16LE();
stk.push(value);
debugC(3, kDraciBytecodeDebugLevel, "\t\t-number %hu", value);
break;
case kMathOperator:
value = reader.readUint16LE();
stk.pop();
stk.pop();
// FIXME: Pushing dummy value for now, but should push return value
stk.push(0);
debugC(3, kDraciBytecodeDebugLevel, "\t\t-operator %s",
operators[value-1].c_str());
break;
case kMathVariable:
value = reader.readUint16LE();
stk.push(value);
debugC(3, kDraciBytecodeDebugLevel, "\t\t-variable %hu", value);
break;
case kMathFunctionCall:
value = reader.readUint16LE();
stk.pop();
// FIXME: Pushing dummy value for now, but should push return value
stk.push(0);
debugC(3, kDraciBytecodeDebugLevel, "\t\t-functioncall %s",
functions[value-1].c_str());
break;
}
obj = (mathExpressionObject) reader.readUint16LE();
}
return;
}
/**
* @brief Find the current command in the internal table
*
* @param num Command number
* @param subnum Command subnumer
*
* @return NULL if command is not found. Otherwise, a pointer to a GPL2Command
* struct representing the command.
*/
GPL2Command *Script::findCommand(byte num, byte subnum) {
unsigned int i = 0;
while (1) {
// Command not found
if (i >= kNumCommands) {
break;
}
// Return found command
if (gplCommands[i]._number == num &&
gplCommands[i]._subNumber == subnum) {
return &gplCommands[i];
}
++i;
}
return NULL;
}
/**
* @brief GPL2 bytecode disassembler
* @param gplcode A pointer to the bytecode
* @param len Length of the bytecode
*
* GPL2 is short for Game Programming Language 2 which is the script language
* used by Draci Historie. This is a simple disassembler for the language.
*
* A compiled GPL2 program consists of a stream of bytes representing commands
* and their parameters. The syntax is as follows:
*
* Syntax of a command:
* <name of the command> <number> <sub-number> <list of parameters...>
*
* Syntax of a parameter:
* - 1: integer number literally passed to the program
* - 2-1: string stored in the reservouir of game strings (i.e. something to be
* displayed) and stored as an index in this list
* - 2-2: string resolved by the compiler (i.e., a path to another file) and
* replaced by an integer index of this entity in the appropriate namespace
* (e.g., the index of the palette, location, ...)
* - 3-0: relative jump to a label defined in this code. Each label must be
* first declared in the beginning of the program.
* - 3-1 .. 3-9: index of an entity in several namespaces, defined in file ident
* - 4: mathematical expression compiled into a postfix format
*
* In the compiled program, parameters of type 1..3 are represented by a single
* 16-bit integer. The called command knows by its definition what namespace the
* value comes from.
*/
int Script::run(byte *gplcode, uint16 len) {
Common::MemoryReadStream reader(gplcode, len);
while (!reader.eos()) {
// read in command pair
uint16 cmdpair = reader.readUint16BE();
// extract high byte, i.e. the command number
byte num = (cmdpair >> 8) & 0xFF;
// extract low byte, i.e. the command subnumber
byte subnum = cmdpair & 0xFF;
GPL2Command *cmd;
if ((cmd = findCommand(num, subnum))) {
// Print command name
debugC(2, kDraciBytecodeDebugLevel, "%s", cmd->_name.c_str());
for (uint16 i = 0; i < cmd->_numParams; ++i) {
if (cmd->_paramTypes[i] == 4) {
debugC(3, kDraciBytecodeDebugLevel, "\t<MATHEXPR>");
handleMathExpression(reader);
}
else {
debugC(3, kDraciBytecodeDebugLevel, "\t%hu", reader.readUint16LE());
}
}
}
else {
debugC(2, kDraciBytecodeDebugLevel, "Unknown opcode %hu, %hu",
num, subnum);
}
}
return 0;
}
}
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