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script.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2004-2006 The ScummVM project
 *
 * 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: https://svn.sourceforge.net/svnroot/scummvm/scummvm/tags/release-0-9-1/engines/kyra/script.cpp $
 * $Id: script.cpp 22558 2006-05-21 15:41:32Z lordhoto $
 *
 */

#include "common/stdafx.h"
#include "common/endian.h"
#include "common/stream.h"
#include "common/util.h"
#include "common/system.h"
#include "kyra/kyra.h"
#include "kyra/resource.h"
#include "kyra/script.h"

#define FORM_CHUNK 0x4D524F46
#define TEXT_CHUNK 0x54584554
#define DATA_CHUNK 0x41544144
#define ORDR_CHUNK 0x5244524F

namespace Kyra {
ScriptHelper::ScriptHelper(KyraEngine *vm) : _vm(vm) {
#define COMMAND(x) { &ScriptHelper::x, #x }
      // now we create a list of all Command/Opcode procs and so
      static CommandEntry commandProcs[] = {
            // 0x00
            COMMAND(c1_jmpTo),
            COMMAND(c1_setRetValue),
            COMMAND(c1_pushRetOrPos),
            COMMAND(c1_push),
            // 0x04
            COMMAND(c1_push),
            COMMAND(c1_pushVar),
            COMMAND(c1_pushBPNeg),
            COMMAND(c1_pushBPAdd),
            // 0x08
            COMMAND(c1_popRetOrPos),
            COMMAND(c1_popVar),
            COMMAND(c1_popBPNeg),
            COMMAND(c1_popBPAdd),
            // 0x0C
            COMMAND(c1_addSP),
            COMMAND(c1_subSP),
            COMMAND(c1_execOpcode),
            COMMAND(c1_ifNotJmp),
            // 0x10
            COMMAND(c1_negate),
            COMMAND(c1_eval),
            COMMAND(c1_setRetAndJmp)
      };
      _commands = commandProcs;
#undef COMMAND
}

ScriptHelper::~ScriptHelper() {
}

bool ScriptHelper::loadScript(const char *filename, ScriptData *scriptData, KyraEngine::OpcodeProc *opcodes, int opcodeSize, byte *specialPtr) {
      uint32 size = 0;
      uint8 *data = _vm->resource()->fileData(filename, &size);   
      byte *curData = data;
      
      uint32 formBlockSize = getFORMBlockSize(curData);
      if (formBlockSize == (uint32)-1) {
            delete [] data;
            error("No FORM chunk found in file: '%s'", filename);
            return false;
      }
      
      uint32 chunkSize = getIFFBlockSize(data, curData, size, TEXT_CHUNK);
      if (chunkSize != (uint32)-1) {
            if (specialPtr) {
                  scriptData->mustBeFreed = 0;
                  scriptData->text = specialPtr;
                  specialPtr += chunkSize;
            } else {
                  scriptData->mustBeFreed = 1;
                  scriptData->text = new byte[chunkSize];
            }
            if (!loadIFFBlock(data, curData, size, TEXT_CHUNK, scriptData->text, chunkSize)) {
                  delete [] data;
                  unloadScript(scriptData);
                  error("Couldn't load TEXT chunk from file: '%s'", filename);
                  return false;
            }
      }
      
      chunkSize = getIFFBlockSize(data, curData, size, ORDR_CHUNK);
      if (chunkSize == (uint32)-1) {
            delete [] data;
            unloadScript(scriptData);
            error("No ORDR chunk found in file: '%s'", filename);
            return false;
      }
      if (specialPtr) {
            scriptData->mustBeFreed = 0;
            scriptData->ordr = specialPtr;
            specialPtr += chunkSize;
      } else {
            scriptData->mustBeFreed = 1;
            scriptData->ordr = new byte[chunkSize];
      }
      if (!loadIFFBlock(data, curData, size, ORDR_CHUNK, scriptData->ordr, chunkSize)) {
            delete [] data;
            unloadScript(scriptData);
            error("Couldn't load ORDR chunk from file: '%s'", filename);
            return false;
      }
      chunkSize = chunkSize / 2;
      while (chunkSize--) {
            ((uint16*)scriptData->ordr)[chunkSize] = READ_BE_UINT16(&((uint16*)scriptData->ordr)[chunkSize]);
      }
      
      chunkSize = getIFFBlockSize(data, curData, size, DATA_CHUNK);
      if (chunkSize == (uint32)-1) {
            delete [] data;
            unloadScript(scriptData);
            error("No DATA chunk found in file: '%s'", filename);
            return false;
      }
      if (specialPtr) {
            scriptData->mustBeFreed = 0;
            scriptData->data = specialPtr;
            specialPtr += chunkSize;
      } else {
            scriptData->mustBeFreed = 1;
            scriptData->data = new byte[chunkSize];
      }
      if (!loadIFFBlock(data, curData, size, DATA_CHUNK, scriptData->data, chunkSize)) {
            delete [] data;
            unloadScript(scriptData);
            error("Couldn't load DATA chunk from file: '%s'", filename);
            return false;
      }
      scriptData->dataSize = chunkSize / 2;
      scriptData->opcodes = opcodes;
      scriptData->opcodeSize = opcodeSize;
      
      delete [] data;
      return true;
}

void ScriptHelper::unloadScript(ScriptData *data) {
      if (!data)
            return;

      if (data->mustBeFreed) {
            delete [] data->text;
            delete [] data->ordr;
            delete [] data->data;
      }
      
      data->mustBeFreed = 0;
      data->text = data->ordr = data->data = 0;
}

void ScriptHelper::initScript(ScriptState *scriptStat, ScriptData *data) {
      scriptStat->dataPtr = data;
      scriptStat->ip = 0;
      scriptStat->stack[60] = 0;
      scriptStat->bp = 62;
      scriptStat->sp = 60;
}

bool ScriptHelper::startScript(ScriptState *script, int function) {
      if (!script->dataPtr) {
            return false;
      }
      uint16 functionOffset = ((uint16*)script->dataPtr->ordr)[function];
      if (functionOffset == (uint16)-1) {
            return false;
      }
      script->ip = &script->dataPtr->data[functionOffset*2];
      return true;
}

bool ScriptHelper::validScript(ScriptState *script) {
      if (!script->ip || !script->dataPtr || _vm->quit())
            return false;
      return true;
}

bool ScriptHelper::runScript(ScriptState *script) {
      _parameter = 0;
      _continue = true;
      
      if (!script->ip) {
            return false;
      }
      
      int16 code = READ_BE_UINT16(script->ip); script->ip += 2;
      int16 opcode = (code >> 8) & 0x1F;

      if (code & 0x8000) {
            opcode = 0;
            _parameter = code & 0x7FFF;
      } else if (code & 0x4000) {
            _parameter = (int8)(code);
      } else if (code & 0x2000) {
            _parameter = READ_BE_UINT16(script->ip); script->ip += 2;
      } else {
            _parameter = 0;
      }
      
      if (opcode > 18) {
            error("Script unknown command: %d", opcode);
      } else {
            debugC(5, kDebugLevelScript, "%s([%d/%u])", _commands[opcode].desc, _parameter, (uint)_parameter);
            (this->*(_commands[opcode].proc))(script);
      }
      
      return _continue;
}

uint32 ScriptHelper::getFORMBlockSize(byte *&data) const {
      static const uint32 chunkName = FORM_CHUNK;
      if (READ_LE_UINT32(data) != chunkName) {
            return (uint32)-1;
      }
      data += 4;
      uint32 retValue = READ_BE_UINT32(data); data += 4;
      return retValue;
}

uint32 ScriptHelper::getIFFBlockSize(byte *start, byte *&data, uint32 maxSize, const uint32 chunkName) const {
      uint32 size = (uint32)-1;
      bool special = false;
      
      if (data == (start + maxSize)) {
            data = start + 0x0C;
      }
      while (data < (start + maxSize)) {
            uint32 chunk = READ_LE_UINT32(data); data += 4;
            uint32 size_temp = READ_BE_UINT32(data); data += 4;
            if (chunk != chunkName) {
                  if (special) {
                        data += (size_temp + 1) & 0xFFFFFFFE;
                  } else {
                        data = start + 0x0C;
                        special = true;
                  }
            } else {
                  // kill our data
                  data = start;
                  size = size_temp;
                  break;
            }
      }
      return size;
}

bool ScriptHelper::loadIFFBlock(byte *start, byte *&data, uint32 maxSize, const uint32 chunkName, byte *loadTo, uint32 ptrSize) const {
      bool special = false;
      
      if (data == (start + maxSize)) {
            data = start + 0x0C;
      }
      while (data < (start + maxSize)) {
            uint32 chunk = READ_LE_UINT32(data); data += 4;
            uint32 chunkSize = READ_BE_UINT32(data); data += 4;
            if (chunk != chunkName) {
                  if (special) {
                        data += (chunkSize + 1) & 0xFFFFFFFE;
                  } else {
                        data = start + 0x0C;
                        special = true;
                  }
            } else {
                  uint32 loadSize = 0;
                  if (chunkSize < ptrSize)
                        loadSize = chunkSize;
                  else
                        loadSize = ptrSize;
                  memcpy(loadTo, data, loadSize);
                  chunkSize = (chunkSize + 1) & 0xFFFFFFFE;
                  if (chunkSize > loadSize) {
                        data += (chunkSize - loadSize);
                  }
                  return true;
            }
      }
      return false;
}

#pragma mark -
#pragma mark - Command implementations
#pragma mark -

void ScriptHelper::c1_jmpTo(ScriptState* script) {
      script->ip = script->dataPtr->data + (_parameter << 1);
}

void ScriptHelper::c1_setRetValue(ScriptState* script) {
      script->retValue = _parameter;
}

void ScriptHelper::c1_pushRetOrPos(ScriptState* script) {
      switch (_parameter) {
      case 0:
            script->stack[--script->sp] = script->retValue;
            break;

      case 1:
            script->stack[--script->sp] = (script->ip - script->dataPtr->data) / 2 + 1;
            script->stack[--script->sp] = script->bp;
            script->bp = script->sp + 2;
            break;

      default:
            _continue = false;
            script->ip = 0;
            break;
      }
}

void ScriptHelper::c1_push(ScriptState* script) {
      script->stack[--script->sp] = _parameter;
}

void ScriptHelper::c1_pushVar(ScriptState* script) {
      script->stack[--script->sp] = script->variables[_parameter];
}

void ScriptHelper::c1_pushBPNeg(ScriptState* script) {
      script->stack[--script->sp] = script->stack[(-(int32)(_parameter + 2)) + script->bp];
}

void ScriptHelper::c1_pushBPAdd(ScriptState* script) {
      script->stack[--script->sp] = script->stack[(_parameter - 1) + script->bp];
}

void ScriptHelper::c1_popRetOrPos(ScriptState* script) {
      switch (_parameter) {
      case 0:
            script->retValue = script->stack[script->sp++];
            break;

      case 1:
            if (script->sp >= 60) {
                  _continue = false;
                  script->ip = 0;
            } else {
                  script->bp = script->stack[script->sp++];
                  script->ip = script->dataPtr->data + (script->stack[script->sp++] << 1);
            }
            break;

      default:
            _continue = false;
            script->ip = 0;
            break;
      }
}

void ScriptHelper::c1_popVar(ScriptState* script) {
      script->variables[_parameter] = script->stack[script->sp++];
}

void ScriptHelper::c1_popBPNeg(ScriptState* script) {
      script->stack[(-(int32)(_parameter + 2)) + script->bp] = script->stack[script->sp++];
}

void ScriptHelper::c1_popBPAdd(ScriptState* script) {
      script->stack[(_parameter - 1) + script->bp] = script->stack[script->sp++];
}

void ScriptHelper::c1_addSP(ScriptState* script) {
      script->sp += _parameter;
}

void ScriptHelper::c1_subSP(ScriptState* script) {
      script->sp -= _parameter;
}

void ScriptHelper::c1_execOpcode(ScriptState* script) {
      assert((uint8)_parameter < script->dataPtr->opcodeSize);
      if (script->dataPtr->opcodes[(uint8)_parameter] == &KyraEngine::cmd_dummy)
            warning("calling unimplemented opcode(0x%.02X)", (uint8)_parameter);
      int val = (_vm->*script->dataPtr->opcodes[(uint8)_parameter])(script);
      assert(script);
      script->retValue = val;
}

void ScriptHelper::c1_ifNotJmp(ScriptState* script) {
      if (!script->stack[script->sp++]) {
            _parameter &= 0x7FFF;
            script->ip = script->dataPtr->data + (_parameter << 1);
      }
}

void ScriptHelper::c1_negate(ScriptState* script) {
      int16 value = script->stack[script->sp];
      switch (_parameter) {
      case 0:
            if (!value) {
                  script->stack[script->sp] = 1;
            } else {
                  script->stack[script->sp] = 0;
            }
            break;

      case 1:
            script->stack[script->sp] = -value;
            break;

      case 2:
            script->stack[script->sp] = ~value;
            break;

      default:
            _continue = false;
            break;
      }
}

void ScriptHelper::c1_eval(ScriptState* script) {
      int16 ret = 0;
      bool error = false;
      
      int16 val1 = script->stack[script->sp++];
      int16 val2 = script->stack[script->sp++];
      
      switch (_parameter) {
      case 0:
            if (!val2 || !val1) {
                  ret = 0;
            } else {
                  ret = 1;
            }
            break;

      case 1:
            if (val2 || val1) {
                  ret = 1;
            } else {
                  ret = 0;
            }
            break;

      case 2:
            if (val1 == val2) {
                  ret = 1;
            } else {
                  ret = 0;
            }
            break;

      case 3:
            if (val1 != val2) {
                  ret = 1;
            } else {
                  ret = 0;
            }
            break;

      case 4:
            if (val1 > val2) {
                  ret = 1;
            } else {
                  ret = 0;
            }
            break;

      case 5:
            if (val1 >= val2) {
                  ret = 1;
            } else {
                  ret = 0;
            }
            break;

      case 6:
            if (val1 < val2) {
                  ret = 1;
            } else {
                  ret = 0;
            }
            break;

      case 7:
            if (val1 <= val2) {
                  ret = 1;
            } else {
                  ret = 0;
            }
            break;

      case 8:
            ret = val1 + val2;
            break;

      case 9:
            ret = val2 - val1;
            break;

      case 10:
            ret = val1 * val2;
            break;

      case 11:
            ret = val2 / val1;
            break;

      case 12:
            ret = val2 >> val1;
            break;

      case 13:
            ret = val2 << val1;
            break;

      case 14:
            ret = val1 & val2;
            break;

      case 15:
            ret = val1 | val2;
            break;

      case 16:
            ret = val2 % val1;
            break;

      case 17:
            ret = val1 ^ val2;
            break;

      default:
            warning("Unknown evaluate func: %d", _parameter);
            error = true;
            break;
      }
      
      if (error) {
            script->ip = 0;
            _continue = false;
      } else {
            script->stack[--script->sp] = ret;
      }
}

void ScriptHelper::c1_setRetAndJmp(ScriptState* script) {
      if (script->sp >= 60) {
            _continue = false;
            script->ip = 0;
      } else {
            script->retValue = script->stack[script->sp++];
            uint16 temp = script->stack[script->sp++];
            script->stack[60] = 0;
            script->ip = &script->dataPtr->data[temp*2];
      }
}
} // end of namespace Kyra

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