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}
313