jma.cpp

linux下的任天堂模拟器代码。供大家参考。

      unsigned char int4_buffer[UINT_SIZE];
      size_t size = get_total_size(files);

      //For each chunk in the file...
      for (size_t remaining_size = size; remaining_size; remaining_size -= chunk_size)
      {
        //Read the compressed size
        stream.read((char *)int4_buffer, UINT_SIZE);
        size_t compressed_size = charp_to_uint(int4_buffer);

        //Allocate memory of the correct size to hold the compressed data in the JMA
        //Throw error on failure as that is unrecoverable from
        try
        {
          compressed_buffer = new unsigned char[compressed_size];
        }
        catch (bad_alloc xa)
        {
          throw(JMA_NO_MEM_ALLOC);
        }

        //Read all the compressed data in
        stream.read((char *)compressed_buffer, compressed_size);

        //Read the expected CRC of compressed data from the file
        stream.read((char *)int4_buffer, UINT_SIZE);

        //If it doesn't match, throw error and cleanup memory
        if (CRC32lib::CRC32(compressed_buffer, compressed_size) != charp_to_uint(int4_buffer))
        {
          delete[] compressed_buffer;
          throw(JMA_BAD_FILE);
        }

        //Decompress the data, cleanup memory on failure
        if (!decompress_lzma_7z(compressed_buffer, compressed_size,
                                decompressed_buffer+size-remaining_size,
                                (remaining_size > chunk_size) ? chunk_size : remaining_size))
        {
          delete[] compressed_buffer;
          throw(JMA_DECOMPRESS_FAILED);
        }
        delete[] compressed_buffer;

        if (remaining_size <= chunk_size) //If we just decompressed the remainder
        {
          break;
        }
      }
    }
    else //Solidly compressed JMA
    {
      unsigned char int4_buffer[UINT_SIZE];

      //Read the size of the compressed data
      stream.read((char *)int4_buffer, UINT_SIZE);
      size_t compressed_size = charp_to_uint(int4_buffer);

      //Get decompressed size
      size_t size = get_total_size(files);

      //Setup access methods for decompression
      ISequentialInStream_Istream compressed_data(stream);
      ISequentialOutStream_Array decompressed_data(reinterpret_cast<char*>(decompressed_buffer), size);

      //Decompress the data
      if (!decompress_lzma_7z(compressed_data, compressed_size, decompressed_data, size))
      {
        throw(JMA_DECOMPRESS_FAILED);
      }

      /*
      //Allocate memory of the right size to hold the compressed data in the JMA
      try
      {
        compressed_buffer = new unsigned char[compressed_size];
      }
      catch (bad_alloc xa)
      {
        throw(JMA_NO_MEM_ALLOC);
      }

      //Copy the compressed data into memory
      stream.read((char *)compressed_buffer, compressed_size);
      size_t size = get_total_size(files);

      //Read the CRC of the compressed data
      stream.read((char *)int4_buffer, UINT_SIZE);

      //If it doesn't match, complain
      if (CRC32lib::CRC32(compressed_buffer, compressed_size) != charp_to_uint(int4_buffer))
      {
        delete[] compressed_buffer;
        throw(JMA_BAD_FILE);
      }

      //Decompress the data
      if (!decompress_lzma_7z(compressed_buffer, compressed_size, decompressed_buffer, size))
      {
        delete[] compressed_buffer;
        throw(JMA_DECOMPRESS_FAILED);
      }
      delete[] compressed_buffer;
      */
    }

    vector<unsigned char *> file_pointers;
    size_t size = 0;

    //For each file, add it's pointer to the vector, size is pointer offset in the buffer
    for (vector<jma_file_info>::iterator i = files.begin(); i != files.end(); i++)
    {
      i->buffer = decompressed_buffer+size;
      file_pointers.push_back(decompressed_buffer+size);
      size += i->size;
    }

    //Return the vector of pointers
    return(file_pointers);
  }

  //Extracts the file with a given name found in the archive to the given buffer
  void jma_open::extract_file(string& name, unsigned char *buffer) throw(jma_errors)
  {
    if (!stream.is_open())
    {
      throw(JMA_NO_OPEN);
    }

    size_t size_to_skip = 0;
    size_t our_file_size = 0;

    //Search through the vector of file information
    for (vector<jma_file_info>::iterator i = files.begin(); i != files.end(); i++)
    {
      if (i->name == name)
      {
        //Set the variable so we can tell we found it
        our_file_size = i->size;
        break;
      }

      //Keep a running total of size
      size_to_skip += i->size;
    }

    if (!our_file_size) //File with the specified name was not found in the archive
    {
      throw(JMA_FILE_NOT_FOUND);
    }

    //If the JMA only contains one file, we can skip a lot of overhead
    if (files.size() == 1)
    {
      get_all_files(buffer);
      return;
    }

    if (chunk_size) //we are using non-solid archive..
    {
      unsigned int chunks_to_skip = size_to_skip / chunk_size;

      //skip over requisite number of chunks
      chunk_seek(chunks_to_skip);

      //Allocate memory for compressed and decompressed data
      unsigned char *comp_buffer = 0, *decomp_buffer = 0;
      try
      {
        //Compressed data size is <= non compressed size
        unsigned char *combined_buffer = new unsigned char[chunk_size*2];
        comp_buffer = combined_buffer;
        decomp_buffer = combined_buffer+chunk_size;
      }
      catch (bad_alloc xa)
      {
        throw(JMA_NO_MEM_ALLOC);
      }

      size_t first_chunk_offset = size_to_skip % chunk_size;
      unsigned char int4_buffer[UINT_SIZE];
      for (size_t i = 0; i < our_file_size;)
      {
        //Get size
        stream.read((char *)int4_buffer, UINT_SIZE);
        size_t compressed_size = charp_to_uint(int4_buffer);

        //Read all the compressed data in
        stream.read((char *)comp_buffer, compressed_size);

        //Read the CRC of the compressed data
        stream.read((char *)int4_buffer, UINT_SIZE);

        //If it doesn't match, complain
        if (CRC32lib::CRC32(comp_buffer, compressed_size) != charp_to_uint(int4_buffer))
        {
          delete[] comp_buffer;
          throw(JMA_BAD_FILE);
        }

        //Decompress chunk
        if (!decompress_lzma_7z(comp_buffer, compressed_size, decomp_buffer, chunk_size))
        {
          delete[] comp_buffer;
          throw(JMA_DECOMPRESS_FAILED);
        }

        size_t copy_amount = our_file_size-i > chunk_size-first_chunk_offset ? chunk_size-first_chunk_offset : our_file_size-i;

        memcpy(buffer+i, decomp_buffer+first_chunk_offset, copy_amount);
        first_chunk_offset = 0; //Set to zero since this is only for the first iteration
        i += copy_amount;
      }
      delete[] comp_buffer;
    }
    else //Solid JMA
    {
      unsigned char *decomp_buffer = 0;
      try
      {
        decomp_buffer = new unsigned char[get_total_size(files)];
      }
      catch (bad_alloc xa)
      {
        throw(JMA_NO_MEM_ALLOC);
      }

      get_all_files(decomp_buffer);

      memcpy(buffer, decomp_buffer+size_to_skip, our_file_size);

      delete[] decomp_buffer;
    }
  }

  bool jma_open::is_solid()
  {
    return(chunk_size ? false : true);
  }

  const char *jma_error_text(jma_errors error)
  {
    switch (error)
    {
      case JMA_NO_CREATE:
        return("JMA could not be created");

      case JMA_NO_MEM_ALLOC:
        return("Memory for JMA could be allocated");

      case JMA_NO_OPEN:
        return("JMA could not be opened");

      case JMA_BAD_FILE:
        return("Invalid/Corrupt JMA");

      case JMA_UNSUPPORTED_VERSION:
        return("JMA version not supported");

      case JMA_COMPRESS_FAILED:
        return("JMA compression failed");

      case JMA_DECOMPRESS_FAILED:
        return("JMA decompression failed");

      case JMA_FILE_NOT_FOUND:
        return("File not found in JMA");
    }
    return("Unknown error");
  }

}