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  • Committer: Chuck Short
  • Date: 2010-09-28 20:38:39 UTC
  • Revision ID: zulcss@ubuntu.com-20100928203839-pgjulytsi9ue63x1
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lib/compression/lzxpress.c
 
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
 
 
59
ssize_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
 
 
233
ssize_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
}