promisor-remote: skip move_to_tail when no-op
[git/git.git] / ewah / ewah_io.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 "strbuf.h"
22
23 int ewah_serialize_to(struct ewah_bitmap *self,
24 int (*write_fun)(void *, const void *, size_t),
25 void *data)
26 {
27 size_t i;
28 eword_t dump[2048];
29 const size_t words_per_dump = sizeof(dump) / sizeof(eword_t);
30 uint32_t bitsize, word_count, rlw_pos;
31
32 const eword_t *buffer;
33 size_t words_left;
34
35 /* 32 bit -- bit size for the map */
36 bitsize = htonl((uint32_t)self->bit_size);
37 if (write_fun(data, &bitsize, 4) != 4)
38 return -1;
39
40 /** 32 bit -- number of compressed 64-bit words */
41 word_count = htonl((uint32_t)self->buffer_size);
42 if (write_fun(data, &word_count, 4) != 4)
43 return -1;
44
45 /** 64 bit x N -- compressed words */
46 buffer = self->buffer;
47 words_left = self->buffer_size;
48
49 while (words_left >= words_per_dump) {
50 for (i = 0; i < words_per_dump; ++i, ++buffer)
51 dump[i] = htonll(*buffer);
52
53 if (write_fun(data, dump, sizeof(dump)) != sizeof(dump))
54 return -1;
55
56 words_left -= words_per_dump;
57 }
58
59 if (words_left) {
60 for (i = 0; i < words_left; ++i, ++buffer)
61 dump[i] = htonll(*buffer);
62
63 if (write_fun(data, dump, words_left * 8) != words_left * 8)
64 return -1;
65 }
66
67 /** 32 bit -- position for the RLW */
68 rlw_pos = (uint8_t*)self->rlw - (uint8_t *)self->buffer;
69 rlw_pos = htonl(rlw_pos / sizeof(eword_t));
70
71 if (write_fun(data, &rlw_pos, 4) != 4)
72 return -1;
73
74 return (3 * 4) + (self->buffer_size * 8);
75 }
76
77 static int write_strbuf(void *user_data, const void *data, size_t len)
78 {
79 struct strbuf *sb = user_data;
80 strbuf_add(sb, data, len);
81 return len;
82 }
83
84 int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *sb)
85 {
86 return ewah_serialize_to(self, write_strbuf, sb);
87 }
88
89 ssize_t ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len)
90 {
91 const uint8_t *ptr = map;
92 size_t data_len;
93 size_t i;
94
95 if (len < sizeof(uint32_t))
96 return error("corrupt ewah bitmap: eof before bit size");
97 self->bit_size = get_be32(ptr);
98 ptr += sizeof(uint32_t);
99 len -= sizeof(uint32_t);
100
101 if (len < sizeof(uint32_t))
102 return error("corrupt ewah bitmap: eof before length");
103 self->buffer_size = self->alloc_size = get_be32(ptr);
104 ptr += sizeof(uint32_t);
105 len -= sizeof(uint32_t);
106
107 REALLOC_ARRAY(self->buffer, self->alloc_size);
108
109 /*
110 * Copy the raw data for the bitmap as a whole chunk;
111 * if we're in a little-endian platform, we'll perform
112 * the endianness conversion in a separate pass to ensure
113 * we're loading 8-byte aligned words.
114 */
115 data_len = st_mult(self->buffer_size, sizeof(eword_t));
116 if (len < data_len)
117 return error("corrupt ewah bitmap: eof in data "
118 "(%"PRIuMAX" bytes short)",
119 (uintmax_t)(data_len - len));
120 memcpy(self->buffer, ptr, data_len);
121 ptr += data_len;
122 len -= data_len;
123
124 for (i = 0; i < self->buffer_size; ++i)
125 self->buffer[i] = ntohll(self->buffer[i]);
126
127 if (len < sizeof(uint32_t))
128 return error("corrupt ewah bitmap: eof before rlw");
129 self->rlw = self->buffer + get_be32(ptr);
130 ptr += sizeof(uint32_t);
131 len -= sizeof(uint32_t);
132
133 return ptr - (const uint8_t *)map;
134 }