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a310d434 NP |
1 | /* |
2 | * diff-delta.c: generate a delta between two buffers | |
3 | * | |
4 | * Many parts of this file have been lifted from LibXDiff version 0.10. | |
5 | * http://www.xmailserver.org/xdiff-lib.html | |
6 | * | |
7 | * LibXDiff was written by Davide Libenzi <davidel@xmailserver.org> | |
8 | * Copyright (C) 2003 Davide Libenzi | |
9 | * | |
10 | * Many mods for GIT usage by Nicolas Pitre <nico@cam.org>, (C) 2005. | |
11 | * | |
12 | * This file is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU Lesser General Public | |
14 | * License as published by the Free Software Foundation; either | |
15 | * version 2.1 of the License, or (at your option) any later version. | |
16 | * | |
17 | * Use of this within git automatically means that the LGPL | |
18 | * licensing gets turned into GPLv2 within this project. | |
19 | */ | |
20 | ||
21 | #include <stdlib.h> | |
8e1454b5 | 22 | #include <string.h> |
a310d434 NP |
23 | #include "delta.h" |
24 | ||
63f17569 | 25 | #include "git-compat-util.h" |
a310d434 | 26 | |
08abe669 NP |
27 | /* maximum hash entry list for the same hash bucket */ |
28 | #define HASH_LIMIT 64 | |
a310d434 | 29 | |
3dc5a9e4 NP |
30 | #define RABIN_SHIFT 23 |
31 | #define RABIN_WINDOW 16 | |
32 | ||
33 | static const unsigned int T[256] = { | |
34 | 0x00000000, 0xab59b4d1, 0x56b369a2, 0xfdeadd73, 0x063f6795, 0xad66d344, | |
35 | 0x508c0e37, 0xfbd5bae6, 0x0c7ecf2a, 0xa7277bfb, 0x5acda688, 0xf1941259, | |
36 | 0x0a41a8bf, 0xa1181c6e, 0x5cf2c11d, 0xf7ab75cc, 0x18fd9e54, 0xb3a42a85, | |
37 | 0x4e4ef7f6, 0xe5174327, 0x1ec2f9c1, 0xb59b4d10, 0x48719063, 0xe32824b2, | |
38 | 0x1483517e, 0xbfdae5af, 0x423038dc, 0xe9698c0d, 0x12bc36eb, 0xb9e5823a, | |
39 | 0x440f5f49, 0xef56eb98, 0x31fb3ca8, 0x9aa28879, 0x6748550a, 0xcc11e1db, | |
40 | 0x37c45b3d, 0x9c9defec, 0x6177329f, 0xca2e864e, 0x3d85f382, 0x96dc4753, | |
41 | 0x6b369a20, 0xc06f2ef1, 0x3bba9417, 0x90e320c6, 0x6d09fdb5, 0xc6504964, | |
42 | 0x2906a2fc, 0x825f162d, 0x7fb5cb5e, 0xd4ec7f8f, 0x2f39c569, 0x846071b8, | |
43 | 0x798aaccb, 0xd2d3181a, 0x25786dd6, 0x8e21d907, 0x73cb0474, 0xd892b0a5, | |
44 | 0x23470a43, 0x881ebe92, 0x75f463e1, 0xdeadd730, 0x63f67950, 0xc8afcd81, | |
45 | 0x354510f2, 0x9e1ca423, 0x65c91ec5, 0xce90aa14, 0x337a7767, 0x9823c3b6, | |
46 | 0x6f88b67a, 0xc4d102ab, 0x393bdfd8, 0x92626b09, 0x69b7d1ef, 0xc2ee653e, | |
47 | 0x3f04b84d, 0x945d0c9c, 0x7b0be704, 0xd05253d5, 0x2db88ea6, 0x86e13a77, | |
48 | 0x7d348091, 0xd66d3440, 0x2b87e933, 0x80de5de2, 0x7775282e, 0xdc2c9cff, | |
49 | 0x21c6418c, 0x8a9ff55d, 0x714a4fbb, 0xda13fb6a, 0x27f92619, 0x8ca092c8, | |
50 | 0x520d45f8, 0xf954f129, 0x04be2c5a, 0xafe7988b, 0x5432226d, 0xff6b96bc, | |
51 | 0x02814bcf, 0xa9d8ff1e, 0x5e738ad2, 0xf52a3e03, 0x08c0e370, 0xa39957a1, | |
52 | 0x584ced47, 0xf3155996, 0x0eff84e5, 0xa5a63034, 0x4af0dbac, 0xe1a96f7d, | |
53 | 0x1c43b20e, 0xb71a06df, 0x4ccfbc39, 0xe79608e8, 0x1a7cd59b, 0xb125614a, | |
54 | 0x468e1486, 0xedd7a057, 0x103d7d24, 0xbb64c9f5, 0x40b17313, 0xebe8c7c2, | |
55 | 0x16021ab1, 0xbd5bae60, 0x6cb54671, 0xc7ecf2a0, 0x3a062fd3, 0x915f9b02, | |
56 | 0x6a8a21e4, 0xc1d39535, 0x3c394846, 0x9760fc97, 0x60cb895b, 0xcb923d8a, | |
57 | 0x3678e0f9, 0x9d215428, 0x66f4eece, 0xcdad5a1f, 0x3047876c, 0x9b1e33bd, | |
58 | 0x7448d825, 0xdf116cf4, 0x22fbb187, 0x89a20556, 0x7277bfb0, 0xd92e0b61, | |
59 | 0x24c4d612, 0x8f9d62c3, 0x7836170f, 0xd36fa3de, 0x2e857ead, 0x85dcca7c, | |
60 | 0x7e09709a, 0xd550c44b, 0x28ba1938, 0x83e3ade9, 0x5d4e7ad9, 0xf617ce08, | |
61 | 0x0bfd137b, 0xa0a4a7aa, 0x5b711d4c, 0xf028a99d, 0x0dc274ee, 0xa69bc03f, | |
62 | 0x5130b5f3, 0xfa690122, 0x0783dc51, 0xacda6880, 0x570fd266, 0xfc5666b7, | |
63 | 0x01bcbbc4, 0xaae50f15, 0x45b3e48d, 0xeeea505c, 0x13008d2f, 0xb85939fe, | |
64 | 0x438c8318, 0xe8d537c9, 0x153feaba, 0xbe665e6b, 0x49cd2ba7, 0xe2949f76, | |
65 | 0x1f7e4205, 0xb427f6d4, 0x4ff24c32, 0xe4abf8e3, 0x19412590, 0xb2189141, | |
66 | 0x0f433f21, 0xa41a8bf0, 0x59f05683, 0xf2a9e252, 0x097c58b4, 0xa225ec65, | |
67 | 0x5fcf3116, 0xf49685c7, 0x033df00b, 0xa86444da, 0x558e99a9, 0xfed72d78, | |
68 | 0x0502979e, 0xae5b234f, 0x53b1fe3c, 0xf8e84aed, 0x17bea175, 0xbce715a4, | |
69 | 0x410dc8d7, 0xea547c06, 0x1181c6e0, 0xbad87231, 0x4732af42, 0xec6b1b93, | |
70 | 0x1bc06e5f, 0xb099da8e, 0x4d7307fd, 0xe62ab32c, 0x1dff09ca, 0xb6a6bd1b, | |
71 | 0x4b4c6068, 0xe015d4b9, 0x3eb80389, 0x95e1b758, 0x680b6a2b, 0xc352defa, | |
72 | 0x3887641c, 0x93ded0cd, 0x6e340dbe, 0xc56db96f, 0x32c6cca3, 0x999f7872, | |
73 | 0x6475a501, 0xcf2c11d0, 0x34f9ab36, 0x9fa01fe7, 0x624ac294, 0xc9137645, | |
74 | 0x26459ddd, 0x8d1c290c, 0x70f6f47f, 0xdbaf40ae, 0x207afa48, 0x8b234e99, | |
75 | 0x76c993ea, 0xdd90273b, 0x2a3b52f7, 0x8162e626, 0x7c883b55, 0xd7d18f84, | |
76 | 0x2c043562, 0x875d81b3, 0x7ab75cc0, 0xd1eee811 | |
77 | }; | |
78 | ||
79 | static const unsigned int U[256] = { | |
80 | 0x00000000, 0x7eb5200d, 0x5633f4cb, 0x2886d4c6, 0x073e5d47, 0x798b7d4a, | |
81 | 0x510da98c, 0x2fb88981, 0x0e7cba8e, 0x70c99a83, 0x584f4e45, 0x26fa6e48, | |
82 | 0x0942e7c9, 0x77f7c7c4, 0x5f711302, 0x21c4330f, 0x1cf9751c, 0x624c5511, | |
83 | 0x4aca81d7, 0x347fa1da, 0x1bc7285b, 0x65720856, 0x4df4dc90, 0x3341fc9d, | |
84 | 0x1285cf92, 0x6c30ef9f, 0x44b63b59, 0x3a031b54, 0x15bb92d5, 0x6b0eb2d8, | |
85 | 0x4388661e, 0x3d3d4613, 0x39f2ea38, 0x4747ca35, 0x6fc11ef3, 0x11743efe, | |
86 | 0x3eccb77f, 0x40799772, 0x68ff43b4, 0x164a63b9, 0x378e50b6, 0x493b70bb, | |
87 | 0x61bda47d, 0x1f088470, 0x30b00df1, 0x4e052dfc, 0x6683f93a, 0x1836d937, | |
88 | 0x250b9f24, 0x5bbebf29, 0x73386bef, 0x0d8d4be2, 0x2235c263, 0x5c80e26e, | |
89 | 0x740636a8, 0x0ab316a5, 0x2b7725aa, 0x55c205a7, 0x7d44d161, 0x03f1f16c, | |
90 | 0x2c4978ed, 0x52fc58e0, 0x7a7a8c26, 0x04cfac2b, 0x73e5d470, 0x0d50f47d, | |
91 | 0x25d620bb, 0x5b6300b6, 0x74db8937, 0x0a6ea93a, 0x22e87dfc, 0x5c5d5df1, | |
92 | 0x7d996efe, 0x032c4ef3, 0x2baa9a35, 0x551fba38, 0x7aa733b9, 0x041213b4, | |
93 | 0x2c94c772, 0x5221e77f, 0x6f1ca16c, 0x11a98161, 0x392f55a7, 0x479a75aa, | |
94 | 0x6822fc2b, 0x1697dc26, 0x3e1108e0, 0x40a428ed, 0x61601be2, 0x1fd53bef, | |
95 | 0x3753ef29, 0x49e6cf24, 0x665e46a5, 0x18eb66a8, 0x306db26e, 0x4ed89263, | |
96 | 0x4a173e48, 0x34a21e45, 0x1c24ca83, 0x6291ea8e, 0x4d29630f, 0x339c4302, | |
97 | 0x1b1a97c4, 0x65afb7c9, 0x446b84c6, 0x3adea4cb, 0x1258700d, 0x6ced5000, | |
98 | 0x4355d981, 0x3de0f98c, 0x15662d4a, 0x6bd30d47, 0x56ee4b54, 0x285b6b59, | |
99 | 0x00ddbf9f, 0x7e689f92, 0x51d01613, 0x2f65361e, 0x07e3e2d8, 0x7956c2d5, | |
100 | 0x5892f1da, 0x2627d1d7, 0x0ea10511, 0x7014251c, 0x5facac9d, 0x21198c90, | |
101 | 0x099f5856, 0x772a785b, 0x4c921c31, 0x32273c3c, 0x1aa1e8fa, 0x6414c8f7, | |
102 | 0x4bac4176, 0x3519617b, 0x1d9fb5bd, 0x632a95b0, 0x42eea6bf, 0x3c5b86b2, | |
103 | 0x14dd5274, 0x6a687279, 0x45d0fbf8, 0x3b65dbf5, 0x13e30f33, 0x6d562f3e, | |
104 | 0x506b692d, 0x2ede4920, 0x06589de6, 0x78edbdeb, 0x5755346a, 0x29e01467, | |
105 | 0x0166c0a1, 0x7fd3e0ac, 0x5e17d3a3, 0x20a2f3ae, 0x08242768, 0x76910765, | |
106 | 0x59298ee4, 0x279caee9, 0x0f1a7a2f, 0x71af5a22, 0x7560f609, 0x0bd5d604, | |
107 | 0x235302c2, 0x5de622cf, 0x725eab4e, 0x0ceb8b43, 0x246d5f85, 0x5ad87f88, | |
108 | 0x7b1c4c87, 0x05a96c8a, 0x2d2fb84c, 0x539a9841, 0x7c2211c0, 0x029731cd, | |
109 | 0x2a11e50b, 0x54a4c506, 0x69998315, 0x172ca318, 0x3faa77de, 0x411f57d3, | |
110 | 0x6ea7de52, 0x1012fe5f, 0x38942a99, 0x46210a94, 0x67e5399b, 0x19501996, | |
111 | 0x31d6cd50, 0x4f63ed5d, 0x60db64dc, 0x1e6e44d1, 0x36e89017, 0x485db01a, | |
112 | 0x3f77c841, 0x41c2e84c, 0x69443c8a, 0x17f11c87, 0x38499506, 0x46fcb50b, | |
113 | 0x6e7a61cd, 0x10cf41c0, 0x310b72cf, 0x4fbe52c2, 0x67388604, 0x198da609, | |
114 | 0x36352f88, 0x48800f85, 0x6006db43, 0x1eb3fb4e, 0x238ebd5d, 0x5d3b9d50, | |
115 | 0x75bd4996, 0x0b08699b, 0x24b0e01a, 0x5a05c017, 0x728314d1, 0x0c3634dc, | |
116 | 0x2df207d3, 0x534727de, 0x7bc1f318, 0x0574d315, 0x2acc5a94, 0x54797a99, | |
117 | 0x7cffae5f, 0x024a8e52, 0x06852279, 0x78300274, 0x50b6d6b2, 0x2e03f6bf, | |
118 | 0x01bb7f3e, 0x7f0e5f33, 0x57888bf5, 0x293dabf8, 0x08f998f7, 0x764cb8fa, | |
119 | 0x5eca6c3c, 0x207f4c31, 0x0fc7c5b0, 0x7172e5bd, 0x59f4317b, 0x27411176, | |
120 | 0x1a7c5765, 0x64c97768, 0x4c4fa3ae, 0x32fa83a3, 0x1d420a22, 0x63f72a2f, | |
121 | 0x4b71fee9, 0x35c4dee4, 0x1400edeb, 0x6ab5cde6, 0x42331920, 0x3c86392d, | |
122 | 0x133eb0ac, 0x6d8b90a1, 0x450d4467, 0x3bb8646a | |
123 | }; | |
a310d434 | 124 | |
08abe669 | 125 | struct index_entry { |
a310d434 | 126 | const unsigned char *ptr; |
8e1454b5 | 127 | unsigned int val; |
08abe669 | 128 | struct index_entry *next; |
8e1454b5 | 129 | }; |
a310d434 | 130 | |
08abe669 NP |
131 | struct delta_index { |
132 | const void *src_buf; | |
133 | unsigned long src_size; | |
3dc5a9e4 | 134 | unsigned int hash_mask; |
63f17569 | 135 | struct index_entry *hash[FLEX_ARRAY]; |
08abe669 NP |
136 | }; |
137 | ||
138 | struct delta_index * create_delta_index(const void *buf, unsigned long bufsize) | |
a310d434 | 139 | { |
06a9f920 | 140 | unsigned int i, hsize, hmask, entries, prev_val, *hash_count; |
08abe669 NP |
141 | const unsigned char *data, *buffer = buf; |
142 | struct delta_index *index; | |
143 | struct index_entry *entry, **hash; | |
8e1454b5 | 144 | void *mem; |
06a9f920 | 145 | unsigned long memsize; |
8e1454b5 | 146 | |
08abe669 NP |
147 | if (!buf || !bufsize) |
148 | return NULL; | |
149 | ||
3dc5a9e4 | 150 | /* Determine index hash size. Note that indexing skips the |
82e5a82f | 151 | first byte to allow for optimizing the Rabin's polynomial |
3dc5a9e4 NP |
152 | initialization in create_delta(). */ |
153 | entries = (bufsize - 1) / RABIN_WINDOW; | |
8e1454b5 | 154 | hsize = entries / 4; |
b05faa2d | 155 | for (i = 4; (1u << i) < hsize && i < 31; i++); |
8e1454b5 | 156 | hsize = 1 << i; |
3dc5a9e4 | 157 | hmask = hsize - 1; |
8e1454b5 NP |
158 | |
159 | /* allocate lookup index */ | |
06a9f920 NP |
160 | memsize = sizeof(*index) + |
161 | sizeof(*hash) * hsize + | |
162 | sizeof(*entry) * entries; | |
163 | mem = malloc(memsize); | |
8e1454b5 NP |
164 | if (!mem) |
165 | return NULL; | |
08abe669 NP |
166 | index = mem; |
167 | mem = index + 1; | |
8e1454b5 | 168 | hash = mem; |
08abe669 NP |
169 | mem = hash + hsize; |
170 | entry = mem; | |
171 | ||
172 | index->src_buf = buf; | |
173 | index->src_size = bufsize; | |
3dc5a9e4 | 174 | index->hash_mask = hmask; |
8e1454b5 NP |
175 | memset(hash, 0, hsize * sizeof(*hash)); |
176 | ||
c13c6bf7 NP |
177 | /* allocate an array to count hash entries */ |
178 | hash_count = calloc(hsize, sizeof(*hash_count)); | |
179 | if (!hash_count) { | |
08abe669 | 180 | free(index); |
c13c6bf7 NP |
181 | return NULL; |
182 | } | |
183 | ||
184 | /* then populate the index */ | |
06a9f920 NP |
185 | prev_val = ~0; |
186 | for (data = buffer + entries * RABIN_WINDOW - RABIN_WINDOW; | |
187 | data >= buffer; | |
188 | data -= RABIN_WINDOW) { | |
3dc5a9e4 NP |
189 | unsigned int val = 0; |
190 | for (i = 1; i <= RABIN_WINDOW; i++) | |
191 | val = ((val << 8) | data[i]) ^ T[val >> RABIN_SHIFT]; | |
06a9f920 NP |
192 | if (val == prev_val) { |
193 | /* keep the lowest of consecutive identical blocks */ | |
194 | entry[-1].ptr = data + RABIN_WINDOW; | |
195 | } else { | |
196 | prev_val = val; | |
197 | i = val & hmask; | |
198 | entry->ptr = data + RABIN_WINDOW; | |
199 | entry->val = val; | |
200 | entry->next = hash[i]; | |
201 | hash[i] = entry++; | |
202 | hash_count[i]++; | |
06a9f920 | 203 | } |
3dc5a9e4 | 204 | } |
a310d434 | 205 | |
c13c6bf7 NP |
206 | /* |
207 | * Determine a limit on the number of entries in the same hash | |
82e5a82f | 208 | * bucket. This guards us against pathological data sets causing |
c13c6bf7 NP |
209 | * really bad hash distribution with most entries in the same hash |
210 | * bucket that would bring us to O(m*n) computing costs (m and n | |
211 | * corresponding to reference and target buffer sizes). | |
212 | * | |
08abe669 | 213 | * Make sure none of the hash buckets has more entries than |
c13c6bf7 NP |
214 | * we're willing to test. Otherwise we cull the entry list |
215 | * uniformly to still preserve a good repartition across | |
216 | * the reference buffer. | |
217 | */ | |
218 | for (i = 0; i < hsize; i++) { | |
08abe669 | 219 | if (hash_count[i] < HASH_LIMIT) |
c13c6bf7 NP |
220 | continue; |
221 | entry = hash[i]; | |
222 | do { | |
08abe669 NP |
223 | struct index_entry *keep = entry; |
224 | int skip = hash_count[i] / HASH_LIMIT / 2; | |
c13c6bf7 NP |
225 | do { |
226 | entry = entry->next; | |
227 | } while(--skip && entry); | |
228 | keep->next = entry; | |
229 | } while(entry); | |
230 | } | |
231 | free(hash_count); | |
232 | ||
08abe669 NP |
233 | return index; |
234 | } | |
235 | ||
236 | void free_delta_index(struct delta_index *index) | |
237 | { | |
238 | free(index); | |
a310d434 NP |
239 | } |
240 | ||
3dc5a9e4 NP |
241 | /* |
242 | * The maximum size for any opcode sequence, including the initial header | |
82e5a82f | 243 | * plus Rabin window plus biggest copy. |
3dc5a9e4 NP |
244 | */ |
245 | #define MAX_OP_SIZE (5 + 5 + 1 + RABIN_WINDOW + 7) | |
fe474b58 | 246 | |
08abe669 NP |
247 | void * |
248 | create_delta(const struct delta_index *index, | |
249 | const void *trg_buf, unsigned long trg_size, | |
250 | unsigned long *delta_size, unsigned long max_size) | |
a310d434 | 251 | { |
2d08e5dd | 252 | unsigned int i, outpos, outsize, val; |
5a1fb2ca | 253 | int inscnt; |
8e1454b5 NP |
254 | const unsigned char *ref_data, *ref_top, *data, *top; |
255 | unsigned char *out; | |
a310d434 | 256 | |
08abe669 | 257 | if (!trg_buf || !trg_size) |
8e1454b5 NP |
258 | return NULL; |
259 | ||
a310d434 NP |
260 | outpos = 0; |
261 | outsize = 8192; | |
fe474b58 NP |
262 | if (max_size && outsize >= max_size) |
263 | outsize = max_size + MAX_OP_SIZE + 1; | |
a310d434 | 264 | out = malloc(outsize); |
08abe669 | 265 | if (!out) |
a310d434 | 266 | return NULL; |
a310d434 NP |
267 | |
268 | /* store reference buffer size */ | |
08abe669 NP |
269 | i = index->src_size; |
270 | while (i >= 0x80) { | |
271 | out[outpos++] = i | 0x80; | |
272 | i >>= 7; | |
69a2d426 | 273 | } |
08abe669 | 274 | out[outpos++] = i; |
a310d434 NP |
275 | |
276 | /* store target buffer size */ | |
08abe669 NP |
277 | i = trg_size; |
278 | while (i >= 0x80) { | |
279 | out[outpos++] = i | 0x80; | |
280 | i >>= 7; | |
69a2d426 | 281 | } |
08abe669 | 282 | out[outpos++] = i; |
a310d434 | 283 | |
08abe669 NP |
284 | ref_data = index->src_buf; |
285 | ref_top = ref_data + index->src_size; | |
286 | data = trg_buf; | |
1d7f171c | 287 | top = (const unsigned char *) trg_buf + trg_size; |
3dc5a9e4 NP |
288 | |
289 | outpos++; | |
290 | val = 0; | |
291 | for (i = 0; i < RABIN_WINDOW && data < top; i++, data++) { | |
292 | out[outpos++] = *data; | |
293 | val = ((val << 8) | *data) ^ T[val >> RABIN_SHIFT]; | |
294 | } | |
295 | inscnt = i; | |
a310d434 | 296 | |
8e1454b5 NP |
297 | while (data < top) { |
298 | unsigned int moff = 0, msize = 0; | |
08abe669 | 299 | struct index_entry *entry; |
3dc5a9e4 NP |
300 | val ^= U[data[-RABIN_WINDOW]]; |
301 | val = ((val << 8) | *data) ^ T[val >> RABIN_SHIFT]; | |
2d08e5dd | 302 | i = val & index->hash_mask; |
08abe669 NP |
303 | for (entry = index->hash[i]; entry; entry = entry->next) { |
304 | const unsigned char *ref = entry->ptr; | |
305 | const unsigned char *src = data; | |
306 | unsigned int ref_size = ref_top - ref; | |
307 | if (entry->val != val) | |
308 | continue; | |
309 | if (ref_size > top - src) | |
310 | ref_size = top - src; | |
29f049a0 JH |
311 | if (ref_size > 0x10000) |
312 | ref_size = 0x10000; | |
08abe669 NP |
313 | if (ref_size <= msize) |
314 | break; | |
315 | while (ref_size-- && *src++ == *ref) | |
316 | ref++; | |
317 | if (msize < ref - entry->ptr) { | |
318 | /* this is our best match so far */ | |
319 | msize = ref - entry->ptr; | |
320 | moff = entry->ptr - ref_data; | |
a310d434 NP |
321 | } |
322 | } | |
323 | ||
3dc5a9e4 | 324 | if (msize < 4) { |
a310d434 NP |
325 | if (!inscnt) |
326 | outpos++; | |
327 | out[outpos++] = *data++; | |
328 | inscnt++; | |
329 | if (inscnt == 0x7f) { | |
330 | out[outpos - inscnt - 1] = inscnt; | |
331 | inscnt = 0; | |
332 | } | |
333 | } else { | |
8e1454b5 NP |
334 | unsigned char *op; |
335 | ||
3dc5a9e4 NP |
336 | if (msize >= RABIN_WINDOW) { |
337 | const unsigned char *sk; | |
338 | sk = data + msize - RABIN_WINDOW; | |
339 | val = 0; | |
340 | for (i = 0; i < RABIN_WINDOW; i++) | |
341 | val = ((val << 8) | *sk++) ^ T[val >> RABIN_SHIFT]; | |
342 | } else { | |
343 | const unsigned char *sk = data + 1; | |
344 | for (i = 1; i < msize; i++) { | |
345 | val ^= U[sk[-RABIN_WINDOW]]; | |
346 | val = ((val << 8) | *sk++) ^ T[val >> RABIN_SHIFT]; | |
347 | } | |
348 | } | |
349 | ||
a310d434 | 350 | if (inscnt) { |
5a1fb2ca NP |
351 | while (moff && ref_data[moff-1] == data[-1]) { |
352 | if (msize == 0x10000) | |
353 | break; | |
354 | /* we can match one byte back */ | |
355 | msize++; | |
356 | moff--; | |
357 | data--; | |
358 | outpos--; | |
359 | if (--inscnt) | |
360 | continue; | |
361 | outpos--; /* remove count slot */ | |
362 | inscnt--; /* make it -1 */ | |
363 | break; | |
364 | } | |
a310d434 NP |
365 | out[outpos - inscnt - 1] = inscnt; |
366 | inscnt = 0; | |
367 | } | |
368 | ||
369 | data += msize; | |
8e1454b5 | 370 | op = out + outpos++; |
a310d434 NP |
371 | i = 0x80; |
372 | ||
373 | if (moff & 0xff) { out[outpos++] = moff; i |= 0x01; } | |
374 | moff >>= 8; | |
375 | if (moff & 0xff) { out[outpos++] = moff; i |= 0x02; } | |
376 | moff >>= 8; | |
377 | if (moff & 0xff) { out[outpos++] = moff; i |= 0x04; } | |
378 | moff >>= 8; | |
379 | if (moff & 0xff) { out[outpos++] = moff; i |= 0x08; } | |
380 | ||
381 | if (msize & 0xff) { out[outpos++] = msize; i |= 0x10; } | |
382 | msize >>= 8; | |
383 | if (msize & 0xff) { out[outpos++] = msize; i |= 0x20; } | |
384 | ||
8e1454b5 | 385 | *op = i; |
a310d434 NP |
386 | } |
387 | ||
fe474b58 | 388 | if (outpos >= outsize - MAX_OP_SIZE) { |
a310d434 NP |
389 | void *tmp = out; |
390 | outsize = outsize * 3 / 2; | |
fe474b58 NP |
391 | if (max_size && outsize >= max_size) |
392 | outsize = max_size + MAX_OP_SIZE + 1; | |
393 | if (max_size && outpos > max_size) | |
3dc5a9e4 | 394 | break; |
83572c1a | 395 | out = xrealloc(out, outsize); |
a310d434 NP |
396 | if (!out) { |
397 | free(tmp); | |
a310d434 NP |
398 | return NULL; |
399 | } | |
400 | } | |
401 | } | |
402 | ||
403 | if (inscnt) | |
404 | out[outpos - inscnt - 1] = inscnt; | |
405 | ||
3dc5a9e4 NP |
406 | if (max_size && outpos > max_size) { |
407 | free(out); | |
408 | return NULL; | |
409 | } | |
410 | ||
a310d434 NP |
411 | *delta_size = outpos; |
412 | return out; | |
413 | } |