source: branches/samba-3.5.x/lib/compression/lzxpress.c@ 1075

Last change on this file since 1075 was 414, checked in by Herwig Bauernfeind, 15 years ago

Samba 3.5.0: Initial import
File size: 8.6 KB
Line 
1/*
2 * Copyright (C) Matthieu Suiche 2008
3 *
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the author nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 */
34
35#include "replace.h"
36#include "lzxpress.h"
37
38
39#define __BUF_POS_CONST(buf,ofs)(((const uint8_t *)buf)+(ofs))
40#define __PULL_BYTE(buf,ofs) \
41 ((uint8_t)((*__BUF_POS_CONST(buf,ofs)) & 0xFF))
42
43#ifndef PULL_LE_UINT16
44#define PULL_LE_UINT16(buf,ofs) ((uint16_t)( \
45 ((uint16_t)(((uint16_t)(__PULL_BYTE(buf,(ofs)+0))) << 0)) | \
46 ((uint16_t)(((uint16_t)(__PULL_BYTE(buf,(ofs)+1))) << 8)) \
47))
48#endif
49
50#ifndef PULL_LE_UINT32
51#define PULL_LE_UINT32(buf,ofs) ((uint32_t)( \
52 ((uint32_t)(((uint32_t)(__PULL_BYTE(buf,(ofs)+0))) << 0)) | \
53 ((uint32_t)(((uint32_t)(__PULL_BYTE(buf,(ofs)+1))) << 8)) | \
54 ((uint32_t)(((uint32_t)(__PULL_BYTE(buf,(ofs)+2))) << 16)) | \
55 ((uint32_t)(((uint32_t)(__PULL_BYTE(buf,(ofs)+3))) << 24)) \
56))
57#endif
58
59ssize_t lzxpress_compress(const uint8_t *uncompressed,
60 uint32_t uncompressed_size,
61 uint8_t *compressed,
62 uint32_t max_compressed_size)
63{
64 uint32_t uncompressed_pos, compressed_pos, byte_left;
65 uint32_t max_offset, best_offset;
66 int32_t offset;
67 uint32_t max_len, len, best_len;
68 const uint8_t *str1, *str2;
69 uint32_t indic;
70 uint8_t *indic_pos;
71 uint32_t indic_bit, nibble_index;
72
73 uint32_t metadata_size;
74 uint16_t metadata;
75 uint16_t *dest;
76
77 if (!uncompressed_size) {
78 return 0;
79 }
80
81 uncompressed_pos = 0;
82 indic = 0;
83 compressed_pos = sizeof(uint32_t);
84 indic_pos = &compressed[0];
85
86 byte_left = uncompressed_size;
87 indic_bit = 0;
88 nibble_index = 0;
89
90 if (uncompressed_pos > XPRESS_BLOCK_SIZE)
91 return 0;
92
93 do {
94 bool found = false;
95
96 max_offset = uncompressed_pos;
97
98 str1 = &uncompressed[uncompressed_pos];
99
100 best_len = 2;
101 best_offset = 0;
102
103 max_offset = MIN(0x1FFF, max_offset);
104
105 /* search for the longest match in the window for the lookahead buffer */
106 for (offset = 1; (uint32_t)offset <= max_offset; offset++) {
107 str2 = &str1[-offset];
108
109 /* maximum len we can encode into metadata */
110 max_len = MIN((255 + 15 + 7 + 3), byte_left);
111
112 for (len = 0; (len < max_len) && (str1[len] == str2[len]); len++);
113
114 /*
115 * We check if len is better than the value found before, including the
116 * sequence of identical bytes
117 */
118 if (len > best_len) {
119 found = true;
120 best_len = len;
121 best_offset = offset;
122 }
123 }
124
125 if (found) {
126 metadata_size = 0;
127 dest = (uint16_t *)&compressed[compressed_pos];
128
129 if (best_len < 10) {
130 /* Classical meta-data */
131 metadata = (uint16_t)(((best_offset - 1) << 3) | (best_len - 3));
132 dest[metadata_size / sizeof(uint16_t)] = metadata;
133 metadata_size += sizeof(uint16_t);
134 } else {
135 metadata = (uint16_t)(((best_offset - 1) << 3) | 7);
136 dest[metadata_size / sizeof(uint16_t)] = metadata;
137 metadata_size = sizeof(uint16_t);
138
139 if (best_len < (15 + 7 + 3)) {
140 /* Shared byte */
141 if (!nibble_index) {
142 compressed[compressed_pos + metadata_size] = (best_len - (3 + 7)) & 0xF;
143 metadata_size += sizeof(uint8_t);
144 } else {
145 compressed[nibble_index] &= 0xF;
146 compressed[nibble_index] |= (best_len - (3 + 7)) * 16;
147 }
148 } else if (best_len < (3 + 7 + 15 + 255)) {
149 /* Shared byte */
150 if (!nibble_index) {
151 compressed[compressed_pos + metadata_size] = 15;
152 metadata_size += sizeof(uint8_t);
153 } else {
154 compressed[nibble_index] &= 0xF;
155 compressed[nibble_index] |= (15 * 16);
156 }
157
158 /* Additionnal best_len */
159 compressed[compressed_pos + metadata_size] = (best_len - (3 + 7 + 15)) & 0xFF;
160 metadata_size += sizeof(uint8_t);
161 } else {
162 /* Shared byte */
163 if (!nibble_index) {
164 compressed[compressed_pos + metadata_size] |= 15;
165 metadata_size += sizeof(uint8_t);
166 } else {
167 compressed[nibble_index] |= 15 << 4;
168 }
169
170 /* Additionnal best_len */
171 compressed[compressed_pos + metadata_size] = 255;
172
173 metadata_size += sizeof(uint8_t);
174
175 compressed[compressed_pos + metadata_size] = (best_len - 3) & 0xFF;
176 compressed[compressed_pos + metadata_size + 1] = ((best_len - 3) >> 8) & 0xFF;
177 metadata_size += sizeof(uint16_t);
178 }
179 }
180
181 indic |= 1 << (32 - ((indic_bit % 32) + 1));
182
183 if (best_len > 9) {
184 if (nibble_index == 0) {
185 nibble_index = compressed_pos + sizeof(uint16_t);
186 } else {
187 nibble_index = 0;
188 }
189 }
190
191 compressed_pos += metadata_size;
192 uncompressed_pos += best_len;
193 byte_left -= best_len;
194 } else {
195 compressed[compressed_pos++] = uncompressed[uncompressed_pos++];
196 byte_left--;
197 }
198 indic_bit++;
199
200 if ((indic_bit - 1) % 32 > (indic_bit % 32)) {
201 *(uint32_t *)indic_pos = indic;
202 indic = 0;
203 indic_pos = &compressed[compressed_pos];
204 compressed_pos += sizeof(uint32_t);
205 }
206 } while (byte_left > 3);
207
208 do {
209 compressed[compressed_pos] = uncompressed[uncompressed_pos];
210 indic_bit++;
211
212 uncompressed_pos++;
213 compressed_pos++;
214 if (((indic_bit - 1) % 32) > (indic_bit % 32)){
215 *(uint32_t *)indic_pos = indic;
216 indic = 0;
217 indic_pos = &compressed[compressed_pos];
218 compressed_pos += sizeof(uint32_t);
219 }
220 } while (uncompressed_pos < uncompressed_size);
221
222 if ((indic_bit % 32) > 0) {
223 for (; (indic_bit % 32) != 0; indic_bit++)
224 indic |= 0 << (32 - ((indic_bit % 32) + 1));
225
226 *(uint32_t *)indic_pos = indic;
227 compressed_pos += sizeof(uint32_t);
228 }
229
230 return compressed_pos;
231}
232
233ssize_t lzxpress_decompress(const uint8_t *input,
234 uint32_t input_size,
235 uint8_t *output,
236 uint32_t max_output_size)
237{
238 uint32_t output_index, input_index;
239 uint32_t indicator, indicator_bit;
240 uint32_t length;
241 uint32_t offset;
242 uint32_t nibble_index;
243
244 output_index = 0;
245 input_index = 0;
246 indicator = 0;
247 indicator_bit = 0;
248 length = 0;
249 offset = 0;
250 nibble_index = 0;
251
252 do {
253 if (indicator_bit == 0) {
254 indicator = PULL_LE_UINT32(input, input_index);
255 input_index += sizeof(uint32_t);
256 indicator_bit = 32;
257 }
258 indicator_bit--;
259
260 /*
261 * check whether the bit specified by indicator_bit is set or not
262 * set in indicator. For example, if indicator_bit has value 4
263 * check whether the 4th bit of the value in indicator is set
264 */
265 if (((indicator >> indicator_bit) & 1) == 0) {
266 output[output_index] = input[input_index];
267 input_index += sizeof(uint8_t);
268 output_index += sizeof(uint8_t);
269 } else {
270 length = PULL_LE_UINT16(input, input_index);
271 input_index += sizeof(uint16_t);
272 offset = length / 8;
273 length = length % 8;
274
275 if (length == 7) {
276 if (nibble_index == 0) {
277 nibble_index = input_index;
278 length = input[input_index] % 16;
279 input_index += sizeof(uint8_t);
280 } else {
281 length = input[nibble_index] / 16;
282 nibble_index = 0;
283 }
284
285 if (length == 15) {
286 length = input[input_index];
287 input_index += sizeof(uint8_t);
288 if (length == 255) {
289 length = PULL_LE_UINT16(input, input_index);
290 input_index += sizeof(uint16_t);
291 length -= (15 + 7);
292 }
293 length += 15;
294 }
295 length += 7;
296 }
297
298 length += 3;
299
300 do {
301 if ((output_index >= max_output_size) || ((offset + 1) > output_index)) break;
302
303 output[output_index] = output[output_index - offset - 1];
304
305 output_index += sizeof(uint8_t);
306 length -= sizeof(uint8_t);
307 } while (length != 0);
308 }
309 } while ((output_index < max_output_size) && (input_index < (input_size)));
310
311 return output_index;
312}
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