summaryrefslogtreecommitdiffstats
path: root/lib/lz4/lz4_compress.c
blob: 28321d8f75eff530ca6832f67f0418cf0abad936 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
/*
 * LZ4 - Fast LZ compression algorithm
 * Copyright (C) 2011-2012, Yann Collet.
 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)

 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * You can contact the author at :
 * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
 * - LZ4 source repository : http://code.google.com/p/lz4/
 *
 *  Changed for kernel use by:
 *  Chanho Min <chanho.min@lge.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/lz4.h>
#include <asm/unaligned.h>
#include "lz4defs.h"

/*
 * LZ4_compressCtx :
 * -----------------
 * Compress 'isize' bytes from 'source' into an output buffer 'dest' of
 * maximum size 'maxOutputSize'.  * If it cannot achieve it, compression
 * will stop, and result of the function will be zero.
 * return : the number of bytes written in buffer 'dest', or 0 if the
 * compression fails
 */
static inline int lz4_compressctx(void *ctx,
		const char *source,
		char *dest,
		int isize,
		int maxoutputsize)
{
	HTYPE *hashtable = (HTYPE *)ctx;
	const u8 *ip = (u8 *)source;
#if LZ4_ARCH64
	const BYTE * const base = ip;
#else
	const int base = 0;
#endif
	const u8 *anchor = ip;
	const u8 *const iend = ip + isize;
	const u8 *const mflimit = iend - MFLIMIT;
	#define MATCHLIMIT (iend - LASTLITERALS)

	u8 *op = (u8 *) dest;
	u8 *const oend = op + maxoutputsize;
	int length;
	const int skipstrength = SKIPSTRENGTH;
	u32 forwardh;
	int lastrun;

	/* Init */
	if (isize < MINLENGTH)
		goto _last_literals;

	memset((void *)hashtable, 0, LZ4_MEM_COMPRESS);

	/* First Byte */
	hashtable[LZ4_HASH_VALUE(ip)] = ip - base;
	ip++;
	forwardh = LZ4_HASH_VALUE(ip);

	/* Main Loop */
	for (;;) {
		int findmatchattempts = (1U << skipstrength) + 3;
		const u8 *forwardip = ip;
		const u8 *ref;
		u8 *token;

		/* Find a match */
		do {
			u32 h = forwardh;
			int step = findmatchattempts++ >> skipstrength;
			ip = forwardip;
			forwardip = ip + step;

			if (unlikely(forwardip > mflimit))
				goto _last_literals;

			forwardh = LZ4_HASH_VALUE(forwardip);
			ref = base + hashtable[h];
			hashtable[h] = ip - base;
		} while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));

		/* Catch up */
		while ((ip > anchor) && (ref > (u8 *)source) &&
			unlikely(ip[-1] == ref[-1])) {
			ip--;
			ref--;
		}

		/* Encode Literal length */
		length = (int)(ip - anchor);
		token = op++;
		/* check output limit */
		if (unlikely(op + length + (2 + 1 + LASTLITERALS) +
			(length >> 8) > oend))
			return 0;

		if (length >= (int)RUN_MASK) {
			int len;
			*token = (RUN_MASK << ML_BITS);
			len = length - RUN_MASK;
			for (; len > 254 ; len -= 255)
				*op++ = 255;
			*op++ = (u8)len;
		} else
			*token = (length << ML_BITS);

		/* Copy Literals */
		LZ4_BLINDCOPY(anchor, op, length);
_next_match:
		/* Encode Offset */
		LZ4_WRITE_LITTLEENDIAN_16(op, (u16)(ip - ref));

		/* Start Counting */
		ip += MINMATCH;
		/* MinMatch verified */
		ref += MINMATCH;
		anchor = ip;
		while (likely(ip < MATCHLIMIT - (STEPSIZE - 1))) {
			#if LZ4_ARCH64
			u64 diff = A64(ref) ^ A64(ip);
			#else
			u32 diff = A32(ref) ^ A32(ip);
			#endif
			if (!diff) {
				ip += STEPSIZE;
				ref += STEPSIZE;
				continue;
			}
			ip += LZ4_NBCOMMONBYTES(diff);
			goto _endcount;
		}
		#if LZ4_ARCH64
		if ((ip < (MATCHLIMIT - 3)) && (A32(ref) == A32(ip))) {
			ip += 4;
			ref += 4;
		}
		#endif
		if ((ip < (MATCHLIMIT - 1)) && (A16(ref) == A16(ip))) {
			ip += 2;
			ref += 2;
		}
		if ((ip < MATCHLIMIT) && (*ref == *ip))
			ip++;
_endcount:
		/* Encode MatchLength */
		length = (int)(ip - anchor);
		/* Check output limit */
		if (unlikely(op + (1 + LASTLITERALS) + (length >> 8) > oend))
			return 0;
		if (length >= (int)ML_MASK) {
			*token += ML_MASK;
			length -= ML_MASK;
			for (; length > 509 ; length -= 510) {
				*op++ = 255;
				*op++ = 255;
			}
			if (length > 254) {
				length -= 255;
				*op++ = 255;
			}
			*op++ = (u8)length;
		} else
			*token += length;

		/* Test end of chunk */
		if (ip > mflimit) {
			anchor = ip;
			break;
		}

		/* Fill table */
		hashtable[LZ4_HASH_VALUE(ip-2)] = ip - 2 - base;

		/* Test next position */
		ref = base + hashtable[LZ4_HASH_VALUE(ip)];
		hashtable[LZ4_HASH_VALUE(ip)] = ip - base;
		if ((ref > ip - (MAX_DISTANCE + 1)) && (A32(ref) == A32(ip))) {
			token = op++;
			*token = 0;
			goto _next_match;
		}

		/* Prepare next loop */
		anchor = ip++;
		forwardh = LZ4_HASH_VALUE(ip);
	}

_last_literals:
	/* Encode Last Literals */
	lastrun = (int)(iend - anchor);
	if (((char *)op - dest) + lastrun + 1
		+ ((lastrun + 255 - RUN_MASK) / 255) > (u32)maxoutputsize)
		return 0;

	if (lastrun >= (int)RUN_MASK) {
		*op++ = (RUN_MASK << ML_BITS);
		lastrun -= RUN_MASK;
		for (; lastrun > 254 ; lastrun -= 255)
			*op++ = 255;
		*op++ = (u8)lastrun;
	} else
		*op++ = (lastrun << ML_BITS);
	memcpy(op, anchor, iend - anchor);
	op += iend - anchor;

	/* End */
	return (int)(((char *)op) - dest);
}

static inline int lz4_compress64kctx(void *ctx,
		const char *source,
		char *dest,
		int isize,
		int maxoutputsize)
{
	u16 *hashtable = (u16 *)ctx;
	const u8 *ip = (u8 *) source;
	const u8 *anchor = ip;
	const u8 *const base = ip;
	const u8 *const iend = ip + isize;
	const u8 *const mflimit = iend - MFLIMIT;
	#define MATCHLIMIT (iend - LASTLITERALS)

	u8 *op = (u8 *) dest;
	u8 *const oend = op + maxoutputsize;
	int len, length;
	const int skipstrength = SKIPSTRENGTH;
	u32 forwardh;
	int lastrun;

	/* Init */
	if (isize < MINLENGTH)
		goto _last_literals;

	memset((void *)hashtable, 0, LZ4_MEM_COMPRESS);

	/* First Byte */
	ip++;
	forwardh = LZ4_HASH64K_VALUE(ip);

	/* Main Loop */
	for (;;) {
		int findmatchattempts = (1U << skipstrength) + 3;
		const u8 *forwardip = ip;
		const u8 *ref;
		u8 *token;

		/* Find a match */
		do {
			u32 h = forwardh;
			int step = findmatchattempts++ >> skipstrength;
			ip = forwardip;
			forwardip = ip + step;

			if (forwardip > mflimit)
				goto _last_literals;

			forwardh = LZ4_HASH64K_VALUE(forwardip);
			ref = base + hashtable[h];
			hashtable[h] = (u16)(ip - base);
		} while (A32(ref) != A32(ip));

		/* Catch up */
		while ((ip > anchor) && (ref > (u8 *)source)
			&& (ip[-1] == ref[-1])) {
			ip--;
			ref--;
		}

		/* Encode Literal length */
		length = (int)(ip - anchor);
		token = op++;
		/* Check output limit */
		if (unlikely(op + length + (2 + 1 + LASTLITERALS)
			+ (length >> 8) > oend))
			return 0;
		if (length >= (int)RUN_MASK) {
			*token = (RUN_MASK << ML_BITS);
			len = length - RUN_MASK;
			for (; len > 254 ; len -= 255)
				*op++ = 255;
			*op++ = (u8)len;
		} else
			*token = (length << ML_BITS);

		/* Copy Literals */
		LZ4_BLINDCOPY(anchor, op, length);

_next_match:
		/* Encode Offset */
		LZ4_WRITE_LITTLEENDIAN_16(op, (u16)(ip - ref));

		/* Start Counting */
		ip += MINMATCH;
		/* MinMatch verified */
		ref += MINMATCH;
		anchor = ip;

		while (ip < MATCHLIMIT - (STEPSIZE - 1)) {
			#if LZ4_ARCH64
			u64 diff = A64(ref) ^ A64(ip);
			#else
			u32 diff = A32(ref) ^ A32(ip);
			#endif

			if (!diff) {
				ip += STEPSIZE;
				ref += STEPSIZE;
				continue;
			}
			ip += LZ4_NBCOMMONBYTES(diff);
			goto _endcount;
		}
		#if LZ4_ARCH64
		if ((ip < (MATCHLIMIT - 3)) && (A32(ref) == A32(ip))) {
			ip += 4;
			ref += 4;
		}
		#endif
		if ((ip < (MATCHLIMIT - 1)) && (A16(ref) == A16(ip))) {
			ip += 2;
			ref += 2;
		}
		if ((ip < MATCHLIMIT) && (*ref == *ip))
			ip++;
_endcount:

		/* Encode MatchLength */
		len = (int)(ip - anchor);
		/* Check output limit */
		if (unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend))
			return 0;
		if (len >= (int)ML_MASK) {
			*token += ML_MASK;
			len -= ML_MASK;
			for (; len > 509 ; len -= 510) {
				*op++ = 255;
				*op++ = 255;
			}
			if (len > 254) {
				len -= 255;
				*op++ = 255;
			}
			*op++ = (u8)len;
		} else
			*token += len;

		/* Test end of chunk */
		if (ip > mflimit) {
			anchor = ip;
			break;
		}

		/* Fill table */
		hashtable[LZ4_HASH64K_VALUE(ip-2)] = (u16)(ip - 2 - base);

		/* Test next position */
		ref = base + hashtable[LZ4_HASH64K_VALUE(ip)];
		hashtable[LZ4_HASH64K_VALUE(ip)] = (u16)(ip - base);
		if (A32(ref) == A32(ip)) {
			token = op++;
			*token = 0;
			goto _next_match;
		}

		/* Prepare next loop */
		anchor = ip++;
		forwardh = LZ4_HASH64K_VALUE(ip);
	}

_last_literals:
	/* Encode Last Literals */
	lastrun = (int)(iend - anchor);
	if (op + lastrun + 1 + (lastrun - RUN_MASK + 255) / 255 > oend)
		return 0;
	if (lastrun >= (int)RUN_MASK) {
		*op++ = (RUN_MASK << ML_BITS);
		lastrun -= RUN_MASK;
		for (; lastrun > 254 ; lastrun -= 255)
			*op++ = 255;
		*op++ = (u8)lastrun;
	} else
		*op++ = (lastrun << ML_BITS);
	memcpy(op, anchor, iend - anchor);
	op += iend - anchor;
	/* End */
	return (int)(((char *)op) - dest);
}

int lz4_compress(const unsigned char *src, size_t src_len,
			unsigned char *dst, size_t *dst_len, void *wrkmem)
{
	int ret = -1;
	int out_len = 0;

	if (src_len < LZ4_64KLIMIT)
		out_len = lz4_compress64kctx(wrkmem, src, dst, src_len,
				lz4_compressbound(src_len));
	else
		out_len = lz4_compressctx(wrkmem, src, dst, src_len,
				lz4_compressbound(src_len));

	if (out_len < 0)
		goto exit;

	*dst_len = out_len;

	return 0;
exit:
	return ret;
}
EXPORT_SYMBOL(lz4_compress);

MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION("LZ4 compressor");