promisor-remote: skip move_to_tail when no-op
[git/git.git] / ewah / ewok.h
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1/**
2 * Copyright 2013, GitHub, Inc
3 * Copyright 2009-2013, Daniel Lemire, Cliff Moon,
4 * David McIntosh, Robert Becho, Google Inc. and Veronika Zenz
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version 2
9 * of the License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
48425792 17 * along with this program; if not, see <http://www.gnu.org/licenses/>.
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18 */
19#ifndef __EWOK_BITMAP_H__
20#define __EWOK_BITMAP_H__
21
be0d9d53 22struct strbuf;
e1273106 23typedef uint64_t eword_t;
34b935c0 24#define BITS_IN_EWORD (sizeof(eword_t) * 8)
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25
26/**
27 * Do not use __builtin_popcountll. The GCC implementation
28 * is notoriously slow on all platforms.
29 *
30 * See: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36041
31 */
32static inline uint32_t ewah_bit_popcount64(uint64_t x)
33{
34 x = (x & 0x5555555555555555ULL) + ((x >> 1) & 0x5555555555555555ULL);
35 x = (x & 0x3333333333333333ULL) + ((x >> 2) & 0x3333333333333333ULL);
36 x = (x & 0x0F0F0F0F0F0F0F0FULL) + ((x >> 4) & 0x0F0F0F0F0F0F0F0FULL);
37 return (x * 0x0101010101010101ULL) >> 56;
38}
39
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40/* __builtin_ctzll was not available until 3.4.0 */
41#if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR > 3))
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42#define ewah_bit_ctz64(x) __builtin_ctzll(x)
43#else
44static inline int ewah_bit_ctz64(uint64_t x)
45{
46 int n = 0;
47 if ((x & 0xffffffff) == 0) { x >>= 32; n += 32; }
48 if ((x & 0xffff) == 0) { x >>= 16; n += 16; }
49 if ((x & 0xff) == 0) { x >>= 8; n += 8; }
50 if ((x & 0xf) == 0) { x >>= 4; n += 4; }
51 if ((x & 0x3) == 0) { x >>= 2; n += 2; }
52 if ((x & 0x1) == 0) { x >>= 1; n += 1; }
53 return n + !x;
54}
55#endif
56
57struct ewah_bitmap {
58 eword_t *buffer;
59 size_t buffer_size;
60 size_t alloc_size;
61 size_t bit_size;
62 eword_t *rlw;
63};
64
65typedef void (*ewah_callback)(size_t pos, void *);
66
67struct ewah_bitmap *ewah_pool_new(void);
68void ewah_pool_free(struct ewah_bitmap *self);
69
70/**
71 * Allocate a new EWAH Compressed bitmap
72 */
73struct ewah_bitmap *ewah_new(void);
74
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75/**
76 * Free all the memory of the bitmap
77 */
78void ewah_free(struct ewah_bitmap *self);
79
80int ewah_serialize_to(struct ewah_bitmap *self,
81 int (*write_fun)(void *out, const void *buf, size_t len),
82 void *out);
be0d9d53 83int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *);
e1273106 84
9d2e330b 85ssize_t ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len);
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86
87uint32_t ewah_checksum(struct ewah_bitmap *self);
88
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89/**
90 * Call the given callback with the position of every single bit
91 * that has been set on the bitmap.
92 *
93 * This is an efficient operation that does not fully decompress
94 * the bitmap.
95 */
96void ewah_each_bit(struct ewah_bitmap *self, ewah_callback callback, void *payload);
97
98/**
99 * Set a given bit on the bitmap.
100 *
101 * The bit at position `pos` will be set to true. Because of the
102 * way that the bitmap is compressed, a set bit cannot be unset
103 * later on.
104 *
105 * Furthermore, since the bitmap uses streaming compression, bits
106 * can only set incrementally.
107 *
108 * E.g.
109 * ewah_set(bitmap, 1); // ok
110 * ewah_set(bitmap, 76); // ok
111 * ewah_set(bitmap, 77); // ok
112 * ewah_set(bitmap, 8712800127); // ok
113 * ewah_set(bitmap, 25); // failed, assert raised
114 */
115void ewah_set(struct ewah_bitmap *self, size_t i);
116
117struct ewah_iterator {
118 const eword_t *buffer;
119 size_t buffer_size;
120
121 size_t pointer;
122 eword_t compressed, literals;
123 eword_t rl, lw;
124 int b;
125};
126
127/**
128 * Initialize a new iterator to run through the bitmap in uncompressed form.
129 *
130 * The iterator can be stack allocated. The underlying bitmap must not be freed
131 * before the iteration is over.
132 *
133 * E.g.
134 *
135 * struct ewah_bitmap *bitmap = ewah_new();
136 * struct ewah_iterator it;
137 *
138 * ewah_iterator_init(&it, bitmap);
139 */
140void ewah_iterator_init(struct ewah_iterator *it, struct ewah_bitmap *parent);
141
142/**
143 * Yield every single word in the bitmap in uncompressed form. This is:
144 * yield single words (32-64 bits) where each bit represents an actual
145 * bit from the bitmap.
146 *
147 * Return: true if a word was yield, false if there are no words left
148 */
149int ewah_iterator_next(eword_t *next, struct ewah_iterator *it);
150
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151void ewah_xor(
152 struct ewah_bitmap *ewah_i,
153 struct ewah_bitmap *ewah_j,
154 struct ewah_bitmap *out);
155
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156/**
157 * Direct word access
158 */
159size_t ewah_add_empty_words(struct ewah_bitmap *self, int v, size_t number);
160void ewah_add_dirty_words(
161 struct ewah_bitmap *self, const eword_t *buffer, size_t number, int negate);
162size_t ewah_add(struct ewah_bitmap *self, eword_t word);
163
164
165/**
166 * Uncompressed, old-school bitmap that can be efficiently compressed
167 * into an `ewah_bitmap`.
168 */
169struct bitmap {
170 eword_t *words;
171 size_t word_alloc;
172};
173
174struct bitmap *bitmap_new(void);
175void bitmap_set(struct bitmap *self, size_t pos);
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176int bitmap_get(struct bitmap *self, size_t pos);
177void bitmap_reset(struct bitmap *self);
178void bitmap_free(struct bitmap *self);
179int bitmap_equals(struct bitmap *self, struct bitmap *other);
180int bitmap_is_subset(struct bitmap *self, struct bitmap *super);
181
182struct ewah_bitmap * bitmap_to_ewah(struct bitmap *bitmap);
183struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah);
184
185void bitmap_and_not(struct bitmap *self, struct bitmap *other);
186void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other);
187void bitmap_or(struct bitmap *self, const struct bitmap *other);
188
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189size_t bitmap_popcount(struct bitmap *self);
190
191#endif