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/*
Copyright (C) 2009 Red Hat, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _H_GLZ_DECODER_WINDOW
#define _H_GLZ_DECODER_WINDOW
#include "glz_decoder_config.h"
#include "glz_decoded_image.h"
#include <list>
#include "read_write_mutex.h"
typedef int DecodedImageWinId;
/*
The class represents the lz window of images, which is shared among the glz decoders
*/
class GlzDecoderWindow {
public:
GlzDecoderWindow(GlzDecoderDebug &debug_calls);
virtual ~GlzDecoderWindow();
DecodedImageWinId pre_decode(uint64_t image_id, uint64_t relative_head_id);
void post_decode(GlzDecodedImage *image);
/* NOTE - get_ref_pixel should be called only after pre_decode was called and
before post decode was called */
uint8_t *get_ref_pixel(DecodedImageWinId decoded_image_win_id, int dist_from_ref_image,
int pixel_offset);
void abort();
/* NOTE - clear mustn't be called if the window is currently used by a decoder*/
void clear();
private:
void wait_for_image(int index);
void add_image(GlzDecodedImage *image);
uint8_t* get_pixel_after_image_entered(int image_index, int pixel_offset);
bool will_overflow(uint64_t image_id, uint64_t relative_head_id);
bool is_empty();
DecodedImageWinId pre_decode_update_window(uint64_t image_id, uint64_t relative_head_id);
void pre_decode_finalize();
void post_decode_intialize();
void post_decode_update_window(GlzDecodedImage *image);
void add_pre_decoded_image(uint64_t image_id);
void add_decoded_image(GlzDecodedImage *image);
void narrow_window(GlzDecodedImage *last_added);
void remove_head(uint64_t new_head_image_id);
int calc_image_win_idx(uint64_t image_id);
int calc_realloc_size(uint64_t new_tail_image_id);
void realloc(int size);
void init();
void release_images();
private:
GlzDecodedImage **_images; // cyclic window
int _head_idx; // index in images array (not image id)
uint64_t _tail_image_id;
int _images_capacity;
int _n_images; // _n_images counts all the images in
// the window, including the missing ones
std::list<uint64_t> _missing_list;
Mutex _win_modifiers_mutex;
ReadWriteMutex _win_alloc_rw_mutex;
Mutex _new_image_mutex;
Condition _new_image_cond; // when get_pixel_ref waits for an image
Condition _release_image_cond; // when waiting for the window to narrow.
Condition _win_alloc_cond;
bool _aborting;
GlzDecoderDebug &_debug_calls;
};
inline uint8_t* GlzDecoderWindow::get_pixel_after_image_entered(int image_index,
int pixel_offset)
{
return _images[image_index]->get_pixel_ref(pixel_offset);
}
/* should be called only between pre and post (when realloc mutex is write-locked).
Note that it can't use calc_image_win_idx, since the window is not locked for changes
(that are not reallocation) during decoding.*/
inline uint8_t *GlzDecoderWindow::get_ref_pixel(DecodedImageWinId decoded_image_win_id,
int dist_from_ref_image, int pixel_offset)
{
int ref_image_index = (dist_from_ref_image <= decoded_image_win_id) ?
(decoded_image_win_id - dist_from_ref_image) :
_images_capacity + (decoded_image_win_id - dist_from_ref_image);
if (_images[ref_image_index] == NULL) { // reading image is atomic
wait_for_image(ref_image_index);
}
// after image entered - it won't leave the window till no decoder needs it
return get_pixel_after_image_entered(ref_image_index, pixel_offset);
}
#endif // _H_GLZ_DECODER_WINDOW
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