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Commit | Line | Data |
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a310d434 NP |
1 | /* |
2 | * diff-delta.c: generate a delta between two buffers | |
3 | * | |
366b53c1 NP |
4 | * This code was greatly inspired by parts of LibXDiff from Davide Libenzi |
5 | * http://www.xmailserver.org/xdiff-lib.html | |
a310d434 | 6 | * |
03aa8ff3 | 7 | * Rewritten for GIT by Nicolas Pitre <nico@fluxnic.net>, (C) 2005-2007 |
a310d434 | 8 | * |
366b53c1 NP |
9 | * This code is free software; you can redistribute it and/or modify |
10 | * it under the terms of the GNU General Public License version 2 as | |
11 | * published by the Free Software Foundation. | |
a310d434 NP |
12 | */ |
13 | ||
63f17569 | 14 | #include "git-compat-util.h" |
85023577 | 15 | #include "delta.h" |
a310d434 | 16 | |
08abe669 NP |
17 | /* maximum hash entry list for the same hash bucket */ |
18 | #define HASH_LIMIT 64 | |
a310d434 | 19 | |
3dc5a9e4 NP |
20 | #define RABIN_SHIFT 23 |
21 | #define RABIN_WINDOW 16 | |
22 | ||
23 | static const unsigned int T[256] = { | |
24 | 0x00000000, 0xab59b4d1, 0x56b369a2, 0xfdeadd73, 0x063f6795, 0xad66d344, | |
25 | 0x508c0e37, 0xfbd5bae6, 0x0c7ecf2a, 0xa7277bfb, 0x5acda688, 0xf1941259, | |
26 | 0x0a41a8bf, 0xa1181c6e, 0x5cf2c11d, 0xf7ab75cc, 0x18fd9e54, 0xb3a42a85, | |
27 | 0x4e4ef7f6, 0xe5174327, 0x1ec2f9c1, 0xb59b4d10, 0x48719063, 0xe32824b2, | |
28 | 0x1483517e, 0xbfdae5af, 0x423038dc, 0xe9698c0d, 0x12bc36eb, 0xb9e5823a, | |
29 | 0x440f5f49, 0xef56eb98, 0x31fb3ca8, 0x9aa28879, 0x6748550a, 0xcc11e1db, | |
30 | 0x37c45b3d, 0x9c9defec, 0x6177329f, 0xca2e864e, 0x3d85f382, 0x96dc4753, | |
31 | 0x6b369a20, 0xc06f2ef1, 0x3bba9417, 0x90e320c6, 0x6d09fdb5, 0xc6504964, | |
32 | 0x2906a2fc, 0x825f162d, 0x7fb5cb5e, 0xd4ec7f8f, 0x2f39c569, 0x846071b8, | |
33 | 0x798aaccb, 0xd2d3181a, 0x25786dd6, 0x8e21d907, 0x73cb0474, 0xd892b0a5, | |
34 | 0x23470a43, 0x881ebe92, 0x75f463e1, 0xdeadd730, 0x63f67950, 0xc8afcd81, | |
35 | 0x354510f2, 0x9e1ca423, 0x65c91ec5, 0xce90aa14, 0x337a7767, 0x9823c3b6, | |
36 | 0x6f88b67a, 0xc4d102ab, 0x393bdfd8, 0x92626b09, 0x69b7d1ef, 0xc2ee653e, | |
37 | 0x3f04b84d, 0x945d0c9c, 0x7b0be704, 0xd05253d5, 0x2db88ea6, 0x86e13a77, | |
38 | 0x7d348091, 0xd66d3440, 0x2b87e933, 0x80de5de2, 0x7775282e, 0xdc2c9cff, | |
39 | 0x21c6418c, 0x8a9ff55d, 0x714a4fbb, 0xda13fb6a, 0x27f92619, 0x8ca092c8, | |
40 | 0x520d45f8, 0xf954f129, 0x04be2c5a, 0xafe7988b, 0x5432226d, 0xff6b96bc, | |
41 | 0x02814bcf, 0xa9d8ff1e, 0x5e738ad2, 0xf52a3e03, 0x08c0e370, 0xa39957a1, | |
42 | 0x584ced47, 0xf3155996, 0x0eff84e5, 0xa5a63034, 0x4af0dbac, 0xe1a96f7d, | |
43 | 0x1c43b20e, 0xb71a06df, 0x4ccfbc39, 0xe79608e8, 0x1a7cd59b, 0xb125614a, | |
44 | 0x468e1486, 0xedd7a057, 0x103d7d24, 0xbb64c9f5, 0x40b17313, 0xebe8c7c2, | |
45 | 0x16021ab1, 0xbd5bae60, 0x6cb54671, 0xc7ecf2a0, 0x3a062fd3, 0x915f9b02, | |
46 | 0x6a8a21e4, 0xc1d39535, 0x3c394846, 0x9760fc97, 0x60cb895b, 0xcb923d8a, | |
47 | 0x3678e0f9, 0x9d215428, 0x66f4eece, 0xcdad5a1f, 0x3047876c, 0x9b1e33bd, | |
48 | 0x7448d825, 0xdf116cf4, 0x22fbb187, 0x89a20556, 0x7277bfb0, 0xd92e0b61, | |
49 | 0x24c4d612, 0x8f9d62c3, 0x7836170f, 0xd36fa3de, 0x2e857ead, 0x85dcca7c, | |
50 | 0x7e09709a, 0xd550c44b, 0x28ba1938, 0x83e3ade9, 0x5d4e7ad9, 0xf617ce08, | |
51 | 0x0bfd137b, 0xa0a4a7aa, 0x5b711d4c, 0xf028a99d, 0x0dc274ee, 0xa69bc03f, | |
52 | 0x5130b5f3, 0xfa690122, 0x0783dc51, 0xacda6880, 0x570fd266, 0xfc5666b7, | |
53 | 0x01bcbbc4, 0xaae50f15, 0x45b3e48d, 0xeeea505c, 0x13008d2f, 0xb85939fe, | |
54 | 0x438c8318, 0xe8d537c9, 0x153feaba, 0xbe665e6b, 0x49cd2ba7, 0xe2949f76, | |
55 | 0x1f7e4205, 0xb427f6d4, 0x4ff24c32, 0xe4abf8e3, 0x19412590, 0xb2189141, | |
56 | 0x0f433f21, 0xa41a8bf0, 0x59f05683, 0xf2a9e252, 0x097c58b4, 0xa225ec65, | |
57 | 0x5fcf3116, 0xf49685c7, 0x033df00b, 0xa86444da, 0x558e99a9, 0xfed72d78, | |
58 | 0x0502979e, 0xae5b234f, 0x53b1fe3c, 0xf8e84aed, 0x17bea175, 0xbce715a4, | |
59 | 0x410dc8d7, 0xea547c06, 0x1181c6e0, 0xbad87231, 0x4732af42, 0xec6b1b93, | |
60 | 0x1bc06e5f, 0xb099da8e, 0x4d7307fd, 0xe62ab32c, 0x1dff09ca, 0xb6a6bd1b, | |
61 | 0x4b4c6068, 0xe015d4b9, 0x3eb80389, 0x95e1b758, 0x680b6a2b, 0xc352defa, | |
62 | 0x3887641c, 0x93ded0cd, 0x6e340dbe, 0xc56db96f, 0x32c6cca3, 0x999f7872, | |
63 | 0x6475a501, 0xcf2c11d0, 0x34f9ab36, 0x9fa01fe7, 0x624ac294, 0xc9137645, | |
64 | 0x26459ddd, 0x8d1c290c, 0x70f6f47f, 0xdbaf40ae, 0x207afa48, 0x8b234e99, | |
65 | 0x76c993ea, 0xdd90273b, 0x2a3b52f7, 0x8162e626, 0x7c883b55, 0xd7d18f84, | |
66 | 0x2c043562, 0x875d81b3, 0x7ab75cc0, 0xd1eee811 | |
67 | }; | |
68 | ||
69 | static const unsigned int U[256] = { | |
70 | 0x00000000, 0x7eb5200d, 0x5633f4cb, 0x2886d4c6, 0x073e5d47, 0x798b7d4a, | |
71 | 0x510da98c, 0x2fb88981, 0x0e7cba8e, 0x70c99a83, 0x584f4e45, 0x26fa6e48, | |
72 | 0x0942e7c9, 0x77f7c7c4, 0x5f711302, 0x21c4330f, 0x1cf9751c, 0x624c5511, | |
73 | 0x4aca81d7, 0x347fa1da, 0x1bc7285b, 0x65720856, 0x4df4dc90, 0x3341fc9d, | |
74 | 0x1285cf92, 0x6c30ef9f, 0x44b63b59, 0x3a031b54, 0x15bb92d5, 0x6b0eb2d8, | |
75 | 0x4388661e, 0x3d3d4613, 0x39f2ea38, 0x4747ca35, 0x6fc11ef3, 0x11743efe, | |
76 | 0x3eccb77f, 0x40799772, 0x68ff43b4, 0x164a63b9, 0x378e50b6, 0x493b70bb, | |
77 | 0x61bda47d, 0x1f088470, 0x30b00df1, 0x4e052dfc, 0x6683f93a, 0x1836d937, | |
78 | 0x250b9f24, 0x5bbebf29, 0x73386bef, 0x0d8d4be2, 0x2235c263, 0x5c80e26e, | |
79 | 0x740636a8, 0x0ab316a5, 0x2b7725aa, 0x55c205a7, 0x7d44d161, 0x03f1f16c, | |
80 | 0x2c4978ed, 0x52fc58e0, 0x7a7a8c26, 0x04cfac2b, 0x73e5d470, 0x0d50f47d, | |
81 | 0x25d620bb, 0x5b6300b6, 0x74db8937, 0x0a6ea93a, 0x22e87dfc, 0x5c5d5df1, | |
82 | 0x7d996efe, 0x032c4ef3, 0x2baa9a35, 0x551fba38, 0x7aa733b9, 0x041213b4, | |
83 | 0x2c94c772, 0x5221e77f, 0x6f1ca16c, 0x11a98161, 0x392f55a7, 0x479a75aa, | |
84 | 0x6822fc2b, 0x1697dc26, 0x3e1108e0, 0x40a428ed, 0x61601be2, 0x1fd53bef, | |
85 | 0x3753ef29, 0x49e6cf24, 0x665e46a5, 0x18eb66a8, 0x306db26e, 0x4ed89263, | |
86 | 0x4a173e48, 0x34a21e45, 0x1c24ca83, 0x6291ea8e, 0x4d29630f, 0x339c4302, | |
87 | 0x1b1a97c4, 0x65afb7c9, 0x446b84c6, 0x3adea4cb, 0x1258700d, 0x6ced5000, | |
88 | 0x4355d981, 0x3de0f98c, 0x15662d4a, 0x6bd30d47, 0x56ee4b54, 0x285b6b59, | |
89 | 0x00ddbf9f, 0x7e689f92, 0x51d01613, 0x2f65361e, 0x07e3e2d8, 0x7956c2d5, | |
90 | 0x5892f1da, 0x2627d1d7, 0x0ea10511, 0x7014251c, 0x5facac9d, 0x21198c90, | |
91 | 0x099f5856, 0x772a785b, 0x4c921c31, 0x32273c3c, 0x1aa1e8fa, 0x6414c8f7, | |
92 | 0x4bac4176, 0x3519617b, 0x1d9fb5bd, 0x632a95b0, 0x42eea6bf, 0x3c5b86b2, | |
93 | 0x14dd5274, 0x6a687279, 0x45d0fbf8, 0x3b65dbf5, 0x13e30f33, 0x6d562f3e, | |
94 | 0x506b692d, 0x2ede4920, 0x06589de6, 0x78edbdeb, 0x5755346a, 0x29e01467, | |
95 | 0x0166c0a1, 0x7fd3e0ac, 0x5e17d3a3, 0x20a2f3ae, 0x08242768, 0x76910765, | |
96 | 0x59298ee4, 0x279caee9, 0x0f1a7a2f, 0x71af5a22, 0x7560f609, 0x0bd5d604, | |
97 | 0x235302c2, 0x5de622cf, 0x725eab4e, 0x0ceb8b43, 0x246d5f85, 0x5ad87f88, | |
98 | 0x7b1c4c87, 0x05a96c8a, 0x2d2fb84c, 0x539a9841, 0x7c2211c0, 0x029731cd, | |
99 | 0x2a11e50b, 0x54a4c506, 0x69998315, 0x172ca318, 0x3faa77de, 0x411f57d3, | |
100 | 0x6ea7de52, 0x1012fe5f, 0x38942a99, 0x46210a94, 0x67e5399b, 0x19501996, | |
101 | 0x31d6cd50, 0x4f63ed5d, 0x60db64dc, 0x1e6e44d1, 0x36e89017, 0x485db01a, | |
102 | 0x3f77c841, 0x41c2e84c, 0x69443c8a, 0x17f11c87, 0x38499506, 0x46fcb50b, | |
103 | 0x6e7a61cd, 0x10cf41c0, 0x310b72cf, 0x4fbe52c2, 0x67388604, 0x198da609, | |
104 | 0x36352f88, 0x48800f85, 0x6006db43, 0x1eb3fb4e, 0x238ebd5d, 0x5d3b9d50, | |
105 | 0x75bd4996, 0x0b08699b, 0x24b0e01a, 0x5a05c017, 0x728314d1, 0x0c3634dc, | |
106 | 0x2df207d3, 0x534727de, 0x7bc1f318, 0x0574d315, 0x2acc5a94, 0x54797a99, | |
107 | 0x7cffae5f, 0x024a8e52, 0x06852279, 0x78300274, 0x50b6d6b2, 0x2e03f6bf, | |
108 | 0x01bb7f3e, 0x7f0e5f33, 0x57888bf5, 0x293dabf8, 0x08f998f7, 0x764cb8fa, | |
109 | 0x5eca6c3c, 0x207f4c31, 0x0fc7c5b0, 0x7172e5bd, 0x59f4317b, 0x27411176, | |
110 | 0x1a7c5765, 0x64c97768, 0x4c4fa3ae, 0x32fa83a3, 0x1d420a22, 0x63f72a2f, | |
111 | 0x4b71fee9, 0x35c4dee4, 0x1400edeb, 0x6ab5cde6, 0x42331920, 0x3c86392d, | |
112 | 0x133eb0ac, 0x6d8b90a1, 0x450d4467, 0x3bb8646a | |
113 | }; | |
a310d434 | 114 | |
08abe669 | 115 | struct index_entry { |
a310d434 | 116 | const unsigned char *ptr; |
8e1454b5 | 117 | unsigned int val; |
d2100860 DK |
118 | }; |
119 | ||
120 | struct unpacked_index_entry { | |
121 | struct index_entry entry; | |
122 | struct unpacked_index_entry *next; | |
8e1454b5 | 123 | }; |
a310d434 | 124 | |
08abe669 | 125 | struct delta_index { |
11779e79 | 126 | unsigned long memsize; |
08abe669 NP |
127 | const void *src_buf; |
128 | unsigned long src_size; | |
3dc5a9e4 | 129 | unsigned int hash_mask; |
63f17569 | 130 | struct index_entry *hash[FLEX_ARRAY]; |
08abe669 NP |
131 | }; |
132 | ||
133 | struct delta_index * create_delta_index(const void *buf, unsigned long bufsize) | |
a310d434 | 134 | { |
06a9f920 | 135 | unsigned int i, hsize, hmask, entries, prev_val, *hash_count; |
08abe669 NP |
136 | const unsigned char *data, *buffer = buf; |
137 | struct delta_index *index; | |
d2100860 DK |
138 | struct unpacked_index_entry *entry, **hash; |
139 | struct index_entry *packed_entry, **packed_hash; | |
8e1454b5 | 140 | void *mem; |
06a9f920 | 141 | unsigned long memsize; |
8e1454b5 | 142 | |
08abe669 NP |
143 | if (!buf || !bufsize) |
144 | return NULL; | |
145 | ||
3dc5a9e4 | 146 | /* Determine index hash size. Note that indexing skips the |
82e5a82f | 147 | first byte to allow for optimizing the Rabin's polynomial |
3dc5a9e4 NP |
148 | initialization in create_delta(). */ |
149 | entries = (bufsize - 1) / RABIN_WINDOW; | |
8e1454b5 | 150 | hsize = entries / 4; |
b05faa2d | 151 | for (i = 4; (1u << i) < hsize && i < 31; i++); |
8e1454b5 | 152 | hsize = 1 << i; |
3dc5a9e4 | 153 | hmask = hsize - 1; |
8e1454b5 NP |
154 | |
155 | /* allocate lookup index */ | |
d2100860 | 156 | memsize = sizeof(*hash) * hsize + |
06a9f920 NP |
157 | sizeof(*entry) * entries; |
158 | mem = malloc(memsize); | |
8e1454b5 NP |
159 | if (!mem) |
160 | return NULL; | |
161 | hash = mem; | |
08abe669 NP |
162 | mem = hash + hsize; |
163 | entry = mem; | |
164 | ||
8e1454b5 NP |
165 | memset(hash, 0, hsize * sizeof(*hash)); |
166 | ||
c13c6bf7 NP |
167 | /* allocate an array to count hash entries */ |
168 | hash_count = calloc(hsize, sizeof(*hash_count)); | |
169 | if (!hash_count) { | |
d2100860 | 170 | free(hash); |
c13c6bf7 NP |
171 | return NULL; |
172 | } | |
173 | ||
174 | /* then populate the index */ | |
06a9f920 NP |
175 | prev_val = ~0; |
176 | for (data = buffer + entries * RABIN_WINDOW - RABIN_WINDOW; | |
177 | data >= buffer; | |
178 | data -= RABIN_WINDOW) { | |
3dc5a9e4 NP |
179 | unsigned int val = 0; |
180 | for (i = 1; i <= RABIN_WINDOW; i++) | |
181 | val = ((val << 8) | data[i]) ^ T[val >> RABIN_SHIFT]; | |
06a9f920 NP |
182 | if (val == prev_val) { |
183 | /* keep the lowest of consecutive identical blocks */ | |
d2100860 DK |
184 | entry[-1].entry.ptr = data + RABIN_WINDOW; |
185 | --entries; | |
06a9f920 NP |
186 | } else { |
187 | prev_val = val; | |
188 | i = val & hmask; | |
d2100860 DK |
189 | entry->entry.ptr = data + RABIN_WINDOW; |
190 | entry->entry.val = val; | |
06a9f920 NP |
191 | entry->next = hash[i]; |
192 | hash[i] = entry++; | |
193 | hash_count[i]++; | |
06a9f920 | 194 | } |
3dc5a9e4 | 195 | } |
a310d434 | 196 | |
c13c6bf7 NP |
197 | /* |
198 | * Determine a limit on the number of entries in the same hash | |
82e5a82f | 199 | * bucket. This guards us against pathological data sets causing |
c13c6bf7 NP |
200 | * really bad hash distribution with most entries in the same hash |
201 | * bucket that would bring us to O(m*n) computing costs (m and n | |
202 | * corresponding to reference and target buffer sizes). | |
203 | * | |
08abe669 | 204 | * Make sure none of the hash buckets has more entries than |
c13c6bf7 NP |
205 | * we're willing to test. Otherwise we cull the entry list |
206 | * uniformly to still preserve a good repartition across | |
207 | * the reference buffer. | |
208 | */ | |
209 | for (i = 0; i < hsize; i++) { | |
02e665ce DK |
210 | int acc; |
211 | ||
212 | if (hash_count[i] <= HASH_LIMIT) | |
c13c6bf7 | 213 | continue; |
02e665ce | 214 | |
02e665ce | 215 | /* We leave exactly HASH_LIMIT entries in the bucket */ |
ce85b053 | 216 | entries -= hash_count[i] - HASH_LIMIT; |
02e665ce | 217 | |
c13c6bf7 | 218 | entry = hash[i]; |
02e665ce | 219 | acc = 0; |
ce85b053 NP |
220 | |
221 | /* | |
222 | * Assume that this loop is gone through exactly | |
223 | * HASH_LIMIT times and is entered and left with | |
224 | * acc==0. So the first statement in the loop | |
225 | * contributes (hash_count[i]-HASH_LIMIT)*HASH_LIMIT | |
226 | * to the accumulator, and the inner loop consequently | |
227 | * is run (hash_count[i]-HASH_LIMIT) times, removing | |
228 | * one element from the list each time. Since acc | |
229 | * balances out to 0 at the final run, the inner loop | |
230 | * body can't be left with entry==NULL. So we indeed | |
231 | * encounter entry==NULL in the outer loop only. | |
232 | */ | |
c13c6bf7 | 233 | do { |
02e665ce DK |
234 | acc += hash_count[i] - HASH_LIMIT; |
235 | if (acc > 0) { | |
236 | struct unpacked_index_entry *keep = entry; | |
237 | do { | |
238 | entry = entry->next; | |
239 | acc -= HASH_LIMIT; | |
240 | } while (acc > 0); | |
241 | keep->next = entry->next; | |
242 | } | |
243 | entry = entry->next; | |
244 | } while (entry); | |
c13c6bf7 NP |
245 | } |
246 | free(hash_count); | |
247 | ||
ce85b053 NP |
248 | /* |
249 | * Now create the packed index in array form | |
250 | * rather than linked lists. | |
251 | */ | |
d2100860 DK |
252 | memsize = sizeof(*index) |
253 | + sizeof(*packed_hash) * (hsize+1) | |
254 | + sizeof(*packed_entry) * entries; | |
d2100860 | 255 | mem = malloc(memsize); |
d2100860 DK |
256 | if (!mem) { |
257 | free(hash); | |
258 | return NULL; | |
259 | } | |
260 | ||
261 | index = mem; | |
262 | index->memsize = memsize; | |
263 | index->src_buf = buf; | |
264 | index->src_size = bufsize; | |
265 | index->hash_mask = hmask; | |
266 | ||
f9c5a80c | 267 | mem = index->hash; |
d2100860 DK |
268 | packed_hash = mem; |
269 | mem = packed_hash + (hsize+1); | |
270 | packed_entry = mem; | |
271 | ||
d2100860 | 272 | for (i = 0; i < hsize; i++) { |
ce85b053 NP |
273 | /* |
274 | * Coalesce all entries belonging to one linked list | |
275 | * into consecutive array entries. | |
276 | */ | |
d2100860 DK |
277 | packed_hash[i] = packed_entry; |
278 | for (entry = hash[i]; entry; entry = entry->next) | |
279 | *packed_entry++ = entry->entry; | |
280 | } | |
281 | ||
ce85b053 | 282 | /* Sentinel value to indicate the length of the last hash bucket */ |
d2100860 | 283 | packed_hash[hsize] = packed_entry; |
ce85b053 | 284 | |
d2100860 DK |
285 | assert(packed_entry - (struct index_entry *)mem == entries); |
286 | free(hash); | |
287 | ||
08abe669 NP |
288 | return index; |
289 | } | |
290 | ||
291 | void free_delta_index(struct delta_index *index) | |
292 | { | |
293 | free(index); | |
a310d434 NP |
294 | } |
295 | ||
11779e79 BD |
296 | unsigned long sizeof_delta_index(struct delta_index *index) |
297 | { | |
298 | if (index) | |
299 | return index->memsize; | |
300 | else | |
301 | return 0; | |
302 | } | |
303 | ||
3dc5a9e4 NP |
304 | /* |
305 | * The maximum size for any opcode sequence, including the initial header | |
82e5a82f | 306 | * plus Rabin window plus biggest copy. |
3dc5a9e4 NP |
307 | */ |
308 | #define MAX_OP_SIZE (5 + 5 + 1 + RABIN_WINDOW + 7) | |
fe474b58 | 309 | |
08abe669 NP |
310 | void * |
311 | create_delta(const struct delta_index *index, | |
312 | const void *trg_buf, unsigned long trg_size, | |
313 | unsigned long *delta_size, unsigned long max_size) | |
a310d434 | 314 | { |
84336696 | 315 | unsigned int i, outpos, outsize, moff, msize, val; |
5a1fb2ca | 316 | int inscnt; |
8e1454b5 NP |
317 | const unsigned char *ref_data, *ref_top, *data, *top; |
318 | unsigned char *out; | |
a310d434 | 319 | |
08abe669 | 320 | if (!trg_buf || !trg_size) |
8e1454b5 NP |
321 | return NULL; |
322 | ||
a310d434 NP |
323 | outpos = 0; |
324 | outsize = 8192; | |
fe474b58 NP |
325 | if (max_size && outsize >= max_size) |
326 | outsize = max_size + MAX_OP_SIZE + 1; | |
a310d434 | 327 | out = malloc(outsize); |
08abe669 | 328 | if (!out) |
a310d434 | 329 | return NULL; |
a310d434 NP |
330 | |
331 | /* store reference buffer size */ | |
08abe669 NP |
332 | i = index->src_size; |
333 | while (i >= 0x80) { | |
334 | out[outpos++] = i | 0x80; | |
335 | i >>= 7; | |
69a2d426 | 336 | } |
08abe669 | 337 | out[outpos++] = i; |
a310d434 NP |
338 | |
339 | /* store target buffer size */ | |
08abe669 NP |
340 | i = trg_size; |
341 | while (i >= 0x80) { | |
342 | out[outpos++] = i | 0x80; | |
343 | i >>= 7; | |
69a2d426 | 344 | } |
08abe669 | 345 | out[outpos++] = i; |
a310d434 | 346 | |
08abe669 NP |
347 | ref_data = index->src_buf; |
348 | ref_top = ref_data + index->src_size; | |
349 | data = trg_buf; | |
1d7f171c | 350 | top = (const unsigned char *) trg_buf + trg_size; |
3dc5a9e4 NP |
351 | |
352 | outpos++; | |
353 | val = 0; | |
354 | for (i = 0; i < RABIN_WINDOW && data < top; i++, data++) { | |
355 | out[outpos++] = *data; | |
356 | val = ((val << 8) | *data) ^ T[val >> RABIN_SHIFT]; | |
357 | } | |
358 | inscnt = i; | |
a310d434 | 359 | |
84336696 NP |
360 | moff = 0; |
361 | msize = 0; | |
8e1454b5 | 362 | while (data < top) { |
84336696 NP |
363 | if (msize < 4096) { |
364 | struct index_entry *entry; | |
365 | val ^= U[data[-RABIN_WINDOW]]; | |
366 | val = ((val << 8) | *data) ^ T[val >> RABIN_SHIFT]; | |
367 | i = val & index->hash_mask; | |
d2100860 | 368 | for (entry = index->hash[i]; entry < index->hash[i+1]; entry++) { |
84336696 NP |
369 | const unsigned char *ref = entry->ptr; |
370 | const unsigned char *src = data; | |
371 | unsigned int ref_size = ref_top - ref; | |
372 | if (entry->val != val) | |
373 | continue; | |
374 | if (ref_size > top - src) | |
375 | ref_size = top - src; | |
376 | if (ref_size <= msize) | |
377 | break; | |
378 | while (ref_size-- && *src++ == *ref) | |
379 | ref++; | |
380 | if (msize < ref - entry->ptr) { | |
381 | /* this is our best match so far */ | |
382 | msize = ref - entry->ptr; | |
383 | moff = entry->ptr - ref_data; | |
384 | if (msize >= 4096) /* good enough */ | |
385 | break; | |
386 | } | |
a310d434 NP |
387 | } |
388 | } | |
389 | ||
3dc5a9e4 | 390 | if (msize < 4) { |
a310d434 NP |
391 | if (!inscnt) |
392 | outpos++; | |
393 | out[outpos++] = *data++; | |
394 | inscnt++; | |
395 | if (inscnt == 0x7f) { | |
396 | out[outpos - inscnt - 1] = inscnt; | |
397 | inscnt = 0; | |
398 | } | |
84336696 | 399 | msize = 0; |
a310d434 | 400 | } else { |
84336696 | 401 | unsigned int left; |
8e1454b5 NP |
402 | unsigned char *op; |
403 | ||
a310d434 | 404 | if (inscnt) { |
5a1fb2ca | 405 | while (moff && ref_data[moff-1] == data[-1]) { |
5a1fb2ca NP |
406 | /* we can match one byte back */ |
407 | msize++; | |
408 | moff--; | |
409 | data--; | |
410 | outpos--; | |
411 | if (--inscnt) | |
412 | continue; | |
413 | outpos--; /* remove count slot */ | |
414 | inscnt--; /* make it -1 */ | |
415 | break; | |
416 | } | |
a310d434 NP |
417 | out[outpos - inscnt - 1] = inscnt; |
418 | inscnt = 0; | |
419 | } | |
420 | ||
84336696 NP |
421 | /* A copy op is currently limited to 64KB (pack v2) */ |
422 | left = (msize < 0x10000) ? 0 : (msize - 0x10000); | |
423 | msize -= left; | |
424 | ||
8e1454b5 | 425 | op = out + outpos++; |
a310d434 NP |
426 | i = 0x80; |
427 | ||
84336696 NP |
428 | if (moff & 0x000000ff) |
429 | out[outpos++] = moff >> 0, i |= 0x01; | |
430 | if (moff & 0x0000ff00) | |
431 | out[outpos++] = moff >> 8, i |= 0x02; | |
432 | if (moff & 0x00ff0000) | |
433 | out[outpos++] = moff >> 16, i |= 0x04; | |
434 | if (moff & 0xff000000) | |
435 | out[outpos++] = moff >> 24, i |= 0x08; | |
a310d434 | 436 | |
84336696 NP |
437 | if (msize & 0x00ff) |
438 | out[outpos++] = msize >> 0, i |= 0x10; | |
439 | if (msize & 0xff00) | |
440 | out[outpos++] = msize >> 8, i |= 0x20; | |
a310d434 | 441 | |
8e1454b5 | 442 | *op = i; |
84336696 NP |
443 | |
444 | data += msize; | |
445 | moff += msize; | |
446 | msize = left; | |
447 | ||
448 | if (msize < 4096) { | |
449 | int j; | |
450 | val = 0; | |
451 | for (j = -RABIN_WINDOW; j < 0; j++) | |
452 | val = ((val << 8) | data[j]) | |
453 | ^ T[val >> RABIN_SHIFT]; | |
454 | } | |
a310d434 NP |
455 | } |
456 | ||
fe474b58 | 457 | if (outpos >= outsize - MAX_OP_SIZE) { |
a310d434 NP |
458 | void *tmp = out; |
459 | outsize = outsize * 3 / 2; | |
fe474b58 NP |
460 | if (max_size && outsize >= max_size) |
461 | outsize = max_size + MAX_OP_SIZE + 1; | |
462 | if (max_size && outpos > max_size) | |
3dc5a9e4 | 463 | break; |
b75c6c6d | 464 | out = realloc(out, outsize); |
a310d434 NP |
465 | if (!out) { |
466 | free(tmp); | |
a310d434 NP |
467 | return NULL; |
468 | } | |
469 | } | |
470 | } | |
471 | ||
472 | if (inscnt) | |
473 | out[outpos - inscnt - 1] = inscnt; | |
474 | ||
3dc5a9e4 NP |
475 | if (max_size && outpos > max_size) { |
476 | free(out); | |
477 | return NULL; | |
478 | } | |
479 | ||
a310d434 NP |
480 | *delta_size = outpos; |
481 | return out; | |
482 | } |