source: trunk/libtransmission/bitfield.h @ 12918

Last change on this file since 12918 was 12902, checked in by jordan, 10 years ago

#4496 'freeze when having a huge torrent' -- add a bitfield helper function to init the bitfield from an array of flags.

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1/*
2 * This file Copyright (C) Mnemosyne LLC
3 *
4 * This file is licensed by the GPL version 2. Works owned by the
5 * Transmission project are granted a special exemption to clause 2(b)
6 * so that the bulk of its code can remain under the MIT license.
7 * This exemption does not extend to derived works not owned by
8 * the Transmission project.
9 *
10 * $Id: bitfield.h 12902 2011-09-20 23:39:40Z jordan $
11 */
12
13#ifndef __TRANSMISSION__
14 #error only libtransmission should #include this header.
15#endif
16
17#ifndef TR_BITFIELD_H
18#define TR_BITFIELD_H 1
19
20#include "transmission.h"
21
22/** @brief Implementation of the BitTorrent spec's Bitfield array of bits */
23typedef struct tr_bitfield
24{
25    uint8_t *  bits;
26    size_t     alloc_count;
27
28    size_t     bit_count;
29
30    size_t     true_count;
31
32    /* Special cases for when full or empty but we don't know the bitCount.
33       This occurs when a magnet link's peers send have all / have none */
34    bool       have_all_hint;
35    bool       have_none_hint;
36}
37tr_bitfield;
38
39/***
40****
41***/
42
43void   tr_bitfieldSetHasAll( tr_bitfield* );
44
45void   tr_bitfieldSetHasNone( tr_bitfield* );
46
47void   tr_bitfieldAdd( tr_bitfield*, size_t bit );
48
49void   tr_bitfieldRem( tr_bitfield*, size_t bit );
50
51void   tr_bitfieldAddRange( tr_bitfield*, size_t begin, size_t end );
52
53void   tr_bitfieldRemRange( tr_bitfield*, size_t begin, size_t end );
54
55/***
56****  life cycle
57***/
58
59extern const tr_bitfield TR_BITFIELD_INIT;
60
61void   tr_bitfieldConstruct( tr_bitfield*, size_t bit_count );
62
63static inline void
64tr_bitfieldDestruct( tr_bitfield * b )
65{
66    tr_bitfieldSetHasNone( b );
67}
68
69/***
70****
71***/
72
73void   tr_bitfieldSetFromFlags( tr_bitfield*, const bool * bytes, size_t n );
74
75void   tr_bitfieldSetFromBitfield( tr_bitfield*, const tr_bitfield* );
76
77void   tr_bitfieldSetRaw( tr_bitfield*, const void * bits, size_t byte_count );
78
79void*  tr_bitfieldGetRaw( const tr_bitfield * b, size_t * byte_count );
80
81/***
82****
83***/
84
85size_t  tr_bitfieldCountRange( const tr_bitfield*, size_t begin, size_t end );
86
87size_t  tr_bitfieldCountTrueBits( const tr_bitfield * b );
88
89static inline bool
90tr_bitfieldHasAll( const tr_bitfield * b )
91{
92    return b->bit_count ? ( b->true_count == b->bit_count ) : b->have_all_hint;
93}
94
95static inline bool
96tr_bitfieldHasNone( const tr_bitfield * b )
97{
98    return b->bit_count ? ( b->true_count == 0 ) : b->have_none_hint;
99}
100
101static inline bool
102tr_bitfieldHas( const tr_bitfield * b, size_t n )
103{
104    if( tr_bitfieldHasAll( b ) ) return true;
105    if( tr_bitfieldHasNone( b ) ) return false;
106    if( n>>3u >= b->alloc_count ) return false;
107    return ( b->bits[n>>3u] << ( n & 7u ) & 0x80 ) != 0;
108}
109
110#endif
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