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// -*- mode:objc -*-
/*
** DVRBuffer.h
**
** Copyright 20101
**
** Author: George Nachman
**
** Project: iTerm2
**
** Description: Implements a circular in-memory buffer for storing
** screen images plus some metadata associated with each frame.
**
** 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#import <Cocoa/Cocoa.h>
#import "DVRIndexEntry.h"
// Sequences in a diff frame begin with one byte indicating the type of content
// that follows. The values come from this enum:
enum {
kSameSequence,
kDiffSequence
};
// Types of frames that DVREncoder and DVRDecoder use.
struct timeval;
typedef enum {
DVRFrameTypeKeyFrame,
DVRFrameTypeDiffFrame
} DVRFrameType;
@interface DVRBuffer : NSObject
{
@private
// Points to start of large circular buffer.
char* store_;
// Points into store_ after -[reserve:] is called.
char* scratch_;
// Total size of storage in bytes.
long long capacity_;
// Maps a frame key number to DVRIndexEntry*.
NSMutableDictionary* index_;
// First key in index.
long long firstKey_;
// Next key number to add to index.
long long nextKey_;
// begin may be before or after end. If "-" is an allocated byte and "." is
// a free byte then you can have one of two cases:
//
// begin------end.....
// ----end....begin---
// Beginning of circular buffer's used region.
long long begin_;
// Non-inclusive end of circular buffer's used regino.
long long end_;
// this must always equal index_.
id sanityCheck; // TODO(georgen): remove this after the source of corruption of index_ is found
}
- (id)initWithBufferCapacity:(long long)capacity;
- (void)dealloc;
// Reserve a chunk of memory. Returns true if blocks had to be freed to make room.
// You can get a pointer to the reserved memory with -[scratch].
- (BOOL)reserve:(long long)length;
- (char*)scratch;
// Allocate a block. Returns the assigned key. You must have called -[reserve] first.
// length may less than reserved amount.
- (long long)allocateBlock:(long long)length;
// Free the first block.
- (void)deallocateBlock;
// Return a pointer to the memory for some key or null if it doesn't exist.
- (void*)blockForKey:(long long)key;
// Returns true if there's enough free space without deallocating a block.
- (BOOL)hasSpaceAvailable:(long long)length;
// Returns first/last used keys.
- (long long)firstKey;
- (long long)lastKey;
// Look up an index entry by key.
- (DVRIndexEntry*)entryForKey:(long long)key;
// Total size of storage.
- (long long)capacity;
// Are there no frames?
- (BOOL)isEmpty;
@end
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