text: /*************************************************************************/
  /*  file_access_buffered.cpp                                             */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
  /*                                                                       */
  /* Permission is hereby granted, free of charge, to any person obtaining */
  /* a copy of this software and associated documentation files (the       */
  /* "Software"), to deal in the Software without restriction, including   */
  /* without limitation the rights to use, copy, modify, merge, publish,   */
  /* distribute, sublicense, and/or sell copies of the Software, and to    */
  /* permit persons to whom the Software is furnished to do so, subject to */
  /* the following conditions:                                             */
  /*                                                                       */
  /* The above copyright notice and this permission notice shall be        */
  /* included in all copies or substantial portions of the Software.       */
  /*                                                                       */
  /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
  /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
  /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
  /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
  /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
  /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
  /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
  /*************************************************************************/
  
  #include "file_access_buffered.h"
  
  #include "core/error_macros.h"
  
  Error FileAccessBuffered::set_error(Error p_error) const {
  
  	return (last_error = p_error);
  }
  
  void FileAccessBuffered::set_cache_size(int p_size) {
  
  	cache_size = p_size;
  }
  
  int FileAccessBuffered::get_cache_size() {
  
  	return cache_size;
  }
  
  int FileAccessBuffered::cache_data_left() const {
  
  	if (file.offset >= file.size) {
  		return 0;
  	}
  
  	if (cache.offset == -1 || file.offset < cache.offset || file.offset >= cache.offset + cache.buffer.size()) {
  
  		return read_data_block(file.offset, cache_size);
  	}
  
  	return cache.buffer.size() - (file.offset - cache.offset);
  }
  
  void FileAccessBuffered::seek(size_t p_position) {
  
  	file.offset = p_position;
  }
  
  void FileAccessBuffered::seek_end(int64_t p_position) {
  
  	file.offset = file.size + p_position;
  }
  
  size_t FileAccessBuffered::get_position() const {
  
  	return file.offset;
  }
  
  size_t FileAccessBuffered::get_len() const {
  
  	return file.size;
  }
  
  bool FileAccessBuffered::eof_reached() const {
  
  	return file.offset > file.size;
  }
  
  uint8_t FileAccessBuffered::get_8() const {
  
  	ERR_FAIL_COND_V_MSG(!file.open, 0, "Can't get data, when file is not opened.");
  
  	uint8_t byte = 0;
  	if (cache_data_left() >= 1) {
  
  		byte = cache.buffer[file.offset - cache.offset];
  	}
  
  	++file.offset;
  
  	return byte;
  }
  
  int FileAccessBuffered::get_buffer(uint8_t *p_dest, int p_length) const {
  
  	ERR_FAIL_COND_V_MSG(!file.open, -1, "Can't get buffer, when file is not opened.");
  
  	if (p_length > cache_size) {
  
  		int total_read = 0;
  
  		if (!(cache.offset == -1 || file.offset < cache.offset || file.offset >= cache.offset + cache.buffer.size())) {
  
  			int size = (cache.buffer.size() - (file.offset - cache.offset));
  			size = size - (size % 4);
  			//const uint8_t* read = cache.buffer.ptr();
  			//memcpy(p_dest, read.ptr() + (file.offset - cache.offset), size);
  			memcpy(p_dest, cache.buffer.ptr() + (file.offset - cache.offset), size);
  			p_dest += size;
  			p_length -= size;
  			file.offset += size;
  			total_read += size;
  		}
  
  		int err = read_data_block(file.offset, p_length, p_dest);
  		if (err >= 0) {
  			total_read += err;
  			file.offset += err;
  		}
  
  		return total_read;
  	}
  
  	int to_read = p_length;
  	int total_read = 0;
  	while (to_read > 0) {
  
  		int left = cache_data_left();
  		if (left == 0) {
  			file.offset += to_read;
  			return total_read;
  		}
  		if (left < 0) {
  			return left;
  		}
  
  		int r = MIN(left, to_read);
  		//const uint8_t* read = cache.buffer.ptr();
  		//memcpy(p_dest+total_read, &read.ptr()[file.offset - cache.offset], r);
  		memcpy(p_dest + total_read, cache.buffer.ptr() + (file.offset - cache.offset), r);
  
  		file.offset += r;
  		total_read += r;
  		to_read -= r;
  	}
  
  	return p_length;
  }
  
  bool FileAccessBuffered::is_open() const {
  
  	return file.open;
  }
  
  Error FileAccessBuffered::get_error() const {
  
  	return last_error;
  }
  