blob: 09c56454f0c8e7f50f4152915198a8ab42b6907b (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
#include <zencore/zencore.h>
namespace zen {
/** Content-defined chunking helper
*/
class ZenChunkHelper
{
public:
void SetChunkSize(size_t MinSize, size_t MaxSize, size_t AvgSize);
size_t ScanChunk(const void* DataBytes, size_t ByteCount);
void Reset();
// This controls which chunking approach is used - threshold or
// modulo based. Threshold is faster and generates similarly sized
// chunks
void SetUseThreshold(bool NewState) { m_UseThreshold = NewState; }
inline size_t ChunkSizeMin() const { return m_ChunkSizeMin; }
inline size_t ChunkSizeMax() const { return m_ChunkSizeMax; }
inline size_t ChunkSizeAvg() const { return m_ChunkSizeAvg; }
inline uint64_t BytesScanned() const { return m_BytesScanned; }
static constexpr size_t kNoBoundaryFound = size_t(~0ull);
private:
size_t m_ChunkSizeMin = 0;
size_t m_ChunkSizeMax = 0;
size_t m_ChunkSizeAvg = 0;
uint32_t m_Discriminator = 0; // Computed in SetChunkSize()
uint32_t m_Threshold = 0; // Computed in SetChunkSize()
bool m_UseThreshold = true;
static constexpr size_t kChunkSizeLimitMax = 64 * 1024 * 1024;
static constexpr size_t kChunkSizeLimitMin = 1024;
static constexpr size_t kDefaultAverageChunkSize = 64 * 1024;
static constexpr int kWindowSize = 48;
uint8_t m_Window[kWindowSize];
uint32_t m_WindowSize = 0;
uint32_t m_CurrentHash = 0;
uint32_t m_CurrentChunkSize = 0;
uint64_t m_BytesScanned = 0;
size_t InternalScanChunk(const void* DataBytes, size_t ByteCount);
void InternalReset();
};
} // namespace zen
|