promisor-remote: skip move_to_tail when no-op
[git/git.git] / ewah / ewah_rlw.c
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
17 * along with this program; if not, see <http://www.gnu.org/licenses/>.
18 */
19 #include "git-compat-util.h"
20 #include "ewok.h"
21 #include "ewok_rlw.h"
22
23 static inline int next_word(struct rlw_iterator *it)
24 {
25 if (it->pointer >= it->size)
26 return 0;
27
28 it->rlw.word = &it->buffer[it->pointer];
29 it->pointer += rlw_get_literal_words(it->rlw.word) + 1;
30
31 it->rlw.literal_words = rlw_get_literal_words(it->rlw.word);
32 it->rlw.running_len = rlw_get_running_len(it->rlw.word);
33 it->rlw.running_bit = rlw_get_run_bit(it->rlw.word);
34 it->rlw.literal_word_offset = 0;
35
36 return 1;
37 }
38
39 void rlwit_init(struct rlw_iterator *it, struct ewah_bitmap *from_ewah)
40 {
41 it->buffer = from_ewah->buffer;
42 it->size = from_ewah->buffer_size;
43 it->pointer = 0;
44
45 next_word(it);
46
47 it->literal_word_start = rlwit_literal_words(it) +
48 it->rlw.literal_word_offset;
49 }
50
51 void rlwit_discard_first_words(struct rlw_iterator *it, size_t x)
52 {
53 while (x > 0) {
54 size_t discard;
55
56 if (it->rlw.running_len > x) {
57 it->rlw.running_len -= x;
58 return;
59 }
60
61 x -= it->rlw.running_len;
62 it->rlw.running_len = 0;
63
64 discard = (x > it->rlw.literal_words) ? it->rlw.literal_words : x;
65
66 it->literal_word_start += discard;
67 it->rlw.literal_words -= discard;
68 x -= discard;
69
70 if (x > 0 || rlwit_word_size(it) == 0) {
71 if (!next_word(it))
72 break;
73
74 it->literal_word_start =
75 rlwit_literal_words(it) + it->rlw.literal_word_offset;
76 }
77 }
78 }
79
80 size_t rlwit_discharge(
81 struct rlw_iterator *it, struct ewah_bitmap *out, size_t max, int negate)
82 {
83 size_t index = 0;
84
85 while (index < max && rlwit_word_size(it) > 0) {
86 size_t pd, pl = it->rlw.running_len;
87
88 if (index + pl > max)
89 pl = max - index;
90
91 ewah_add_empty_words(out, it->rlw.running_bit ^ negate, pl);
92 index += pl;
93
94 pd = it->rlw.literal_words;
95 if (pd + index > max)
96 pd = max - index;
97
98 ewah_add_dirty_words(out,
99 it->buffer + it->literal_word_start, pd, negate);
100
101 rlwit_discard_first_words(it, pd + pl);
102 index += pd;
103 }
104
105 return index;
106 }