1/*
2 * LZ4 - Fast LZ compression algorithm
3 * Copyright (C) 2011-2012, Yann Collet.
4 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
5
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met:
9 *
10 *     * Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *     * Redistributions in binary form must reproduce the above
13 * copyright notice, this list of conditions and the following disclaimer
14 * in the documentation and/or other materials provided with the
15 * distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * You can contact the author at :
30 * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
31 * - LZ4 source repository : http://code.google.com/p/lz4/
32 *
33 *  Changed for kernel use by:
34 *  Chanho Min <chanho.min@lge.com>
35 */
36
37#include <linux/module.h>
38#include <linux/kernel.h>
39#include <linux/lz4.h>
40#include <asm/unaligned.h>
41#include "lz4defs.h"
42
43/*
44 * LZ4_compressCtx :
45 * -----------------
46 * Compress 'isize' bytes from 'source' into an output buffer 'dest' of
47 * maximum size 'maxOutputSize'.  * If it cannot achieve it, compression
48 * will stop, and result of the function will be zero.
49 * return : the number of bytes written in buffer 'dest', or 0 if the
50 * compression fails
51 */
52static inline int lz4_compressctx(void *ctx,
53		const char *source,
54		char *dest,
55		int isize,
56		int maxoutputsize)
57{
58	HTYPE *hashtable = (HTYPE *)ctx;
59	const u8 *ip = (u8 *)source;
60#if LZ4_ARCH64
61	const BYTE * const base = ip;
62#else
63	const int base = 0;
64#endif
65	const u8 *anchor = ip;
66	const u8 *const iend = ip + isize;
67	const u8 *const mflimit = iend - MFLIMIT;
68	#define MATCHLIMIT (iend - LASTLITERALS)
69
70	u8 *op = (u8 *) dest;
71	u8 *const oend = op + maxoutputsize;
72	int length;
73	const int skipstrength = SKIPSTRENGTH;
74	u32 forwardh;
75	int lastrun;
76
77	/* Init */
78	if (isize < MINLENGTH)
79		goto _last_literals;
80
81	memset((void *)hashtable, 0, LZ4_MEM_COMPRESS);
82
83	/* First Byte */
84	hashtable[LZ4_HASH_VALUE(ip)] = ip - base;
85	ip++;
86	forwardh = LZ4_HASH_VALUE(ip);
87
88	/* Main Loop */
89	for (;;) {
90		int findmatchattempts = (1U << skipstrength) + 3;
91		const u8 *forwardip = ip;
92		const u8 *ref;
93		u8 *token;
94
95		/* Find a match */
96		do {
97			u32 h = forwardh;
98			int step = findmatchattempts++ >> skipstrength;
99			ip = forwardip;
100			forwardip = ip + step;
101
102			if (unlikely(forwardip > mflimit))
103				goto _last_literals;
104
105			forwardh = LZ4_HASH_VALUE(forwardip);
106			ref = base + hashtable[h];
107			hashtable[h] = ip - base;
108		} while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));
109
110		/* Catch up */
111		while ((ip > anchor) && (ref > (u8 *)source) &&
112			unlikely(ip[-1] == ref[-1])) {
113			ip--;
114			ref--;
115		}
116
117		/* Encode Literal length */
118		length = (int)(ip - anchor);
119		token = op++;
120		/* check output limit */
121		if (unlikely(op + length + (2 + 1 + LASTLITERALS) +
122			(length >> 8) > oend))
123			return 0;
124
125		if (length >= (int)RUN_MASK) {
126			int len;
127			*token = (RUN_MASK << ML_BITS);
128			len = length - RUN_MASK;
129			for (; len > 254 ; len -= 255)
130				*op++ = 255;
131			*op++ = (u8)len;
132		} else
133			*token = (length << ML_BITS);
134
135		/* Copy Literals */
136		LZ4_BLINDCOPY(anchor, op, length);
137_next_match:
138		/* Encode Offset */
139		LZ4_WRITE_LITTLEENDIAN_16(op, (u16)(ip - ref));
140
141		/* Start Counting */
142		ip += MINMATCH;
143		/* MinMatch verified */
144		ref += MINMATCH;
145		anchor = ip;
146		while (likely(ip < MATCHLIMIT - (STEPSIZE - 1))) {
147			#if LZ4_ARCH64
148			u64 diff = A64(ref) ^ A64(ip);
149			#else
150			u32 diff = A32(ref) ^ A32(ip);
151			#endif
152			if (!diff) {
153				ip += STEPSIZE;
154				ref += STEPSIZE;
155				continue;
156			}
157			ip += LZ4_NBCOMMONBYTES(diff);
158			goto _endcount;
159		}
160		#if LZ4_ARCH64
161		if ((ip < (MATCHLIMIT - 3)) && (A32(ref) == A32(ip))) {
162			ip += 4;
163			ref += 4;
164		}
165		#endif
166		if ((ip < (MATCHLIMIT - 1)) && (A16(ref) == A16(ip))) {
167			ip += 2;
168			ref += 2;
169		}
170		if ((ip < MATCHLIMIT) && (*ref == *ip))
171			ip++;
172_endcount:
173		/* Encode MatchLength */
174		length = (int)(ip - anchor);
175		/* Check output limit */
176		if (unlikely(op + (1 + LASTLITERALS) + (length >> 8) > oend))
177			return 0;
178		if (length >= (int)ML_MASK) {
179			*token += ML_MASK;
180			length -= ML_MASK;
181			for (; length > 509 ; length -= 510) {
182				*op++ = 255;
183				*op++ = 255;
184			}
185			if (length > 254) {
186				length -= 255;
187				*op++ = 255;
188			}
189			*op++ = (u8)length;
190		} else
191			*token += length;
192
193		/* Test end of chunk */
194		if (ip > mflimit) {
195			anchor = ip;
196			break;
197		}
198
199		/* Fill table */
200		hashtable[LZ4_HASH_VALUE(ip-2)] = ip - 2 - base;
201
202		/* Test next position */
203		ref = base + hashtable[LZ4_HASH_VALUE(ip)];
204		hashtable[LZ4_HASH_VALUE(ip)] = ip - base;
205		if ((ref > ip - (MAX_DISTANCE + 1)) && (A32(ref) == A32(ip))) {
206			token = op++;
207			*token = 0;
208			goto _next_match;
209		}
210
211		/* Prepare next loop */
212		anchor = ip++;
213		forwardh = LZ4_HASH_VALUE(ip);
214	}
215
216_last_literals:
217	/* Encode Last Literals */
218	lastrun = (int)(iend - anchor);
219	if (((char *)op - dest) + lastrun + 1
220		+ ((lastrun + 255 - RUN_MASK) / 255) > (u32)maxoutputsize)
221		return 0;
222
223	if (lastrun >= (int)RUN_MASK) {
224		*op++ = (RUN_MASK << ML_BITS);
225		lastrun -= RUN_MASK;
226		for (; lastrun > 254 ; lastrun -= 255)
227			*op++ = 255;
228		*op++ = (u8)lastrun;
229	} else
230		*op++ = (lastrun << ML_BITS);
231	memcpy(op, anchor, iend - anchor);
232	op += iend - anchor;
233
234	/* End */
235	return (int)(((char *)op) - dest);
236}
237
238static inline int lz4_compress64kctx(void *ctx,
239		const char *source,
240		char *dest,
241		int isize,
242		int maxoutputsize)
243{
244	u16 *hashtable = (u16 *)ctx;
245	const u8 *ip = (u8 *) source;
246	const u8 *anchor = ip;
247	const u8 *const base = ip;
248	const u8 *const iend = ip + isize;
249	const u8 *const mflimit = iend - MFLIMIT;
250	#define MATCHLIMIT (iend - LASTLITERALS)
251
252	u8 *op = (u8 *) dest;
253	u8 *const oend = op + maxoutputsize;
254	int len, length;
255	const int skipstrength = SKIPSTRENGTH;
256	u32 forwardh;
257	int lastrun;
258
259	/* Init */
260	if (isize < MINLENGTH)
261		goto _last_literals;
262
263	memset((void *)hashtable, 0, LZ4_MEM_COMPRESS);
264
265	/* First Byte */
266	ip++;
267	forwardh = LZ4_HASH64K_VALUE(ip);
268
269	/* Main Loop */
270	for (;;) {
271		int findmatchattempts = (1U << skipstrength) + 3;
272		const u8 *forwardip = ip;
273		const u8 *ref;
274		u8 *token;
275
276		/* Find a match */
277		do {
278			u32 h = forwardh;
279			int step = findmatchattempts++ >> skipstrength;
280			ip = forwardip;
281			forwardip = ip + step;
282
283			if (forwardip > mflimit)
284				goto _last_literals;
285
286			forwardh = LZ4_HASH64K_VALUE(forwardip);
287			ref = base + hashtable[h];
288			hashtable[h] = (u16)(ip - base);
289		} while (A32(ref) != A32(ip));
290
291		/* Catch up */
292		while ((ip > anchor) && (ref > (u8 *)source)
293			&& (ip[-1] == ref[-1])) {
294			ip--;
295			ref--;
296		}
297
298		/* Encode Literal length */
299		length = (int)(ip - anchor);
300		token = op++;
301		/* Check output limit */
302		if (unlikely(op + length + (2 + 1 + LASTLITERALS)
303			+ (length >> 8) > oend))
304			return 0;
305		if (length >= (int)RUN_MASK) {
306			*token = (RUN_MASK << ML_BITS);
307			len = length - RUN_MASK;
308			for (; len > 254 ; len -= 255)
309				*op++ = 255;
310			*op++ = (u8)len;
311		} else
312			*token = (length << ML_BITS);
313
314		/* Copy Literals */
315		LZ4_BLINDCOPY(anchor, op, length);
316
317_next_match:
318		/* Encode Offset */
319		LZ4_WRITE_LITTLEENDIAN_16(op, (u16)(ip - ref));
320
321		/* Start Counting */
322		ip += MINMATCH;
323		/* MinMatch verified */
324		ref += MINMATCH;
325		anchor = ip;
326
327		while (ip < MATCHLIMIT - (STEPSIZE - 1)) {
328			#if LZ4_ARCH64
329			u64 diff = A64(ref) ^ A64(ip);
330			#else
331			u32 diff = A32(ref) ^ A32(ip);
332			#endif
333
334			if (!diff) {
335				ip += STEPSIZE;
336				ref += STEPSIZE;
337				continue;
338			}
339			ip += LZ4_NBCOMMONBYTES(diff);
340			goto _endcount;
341		}
342		#if LZ4_ARCH64
343		if ((ip < (MATCHLIMIT - 3)) && (A32(ref) == A32(ip))) {
344			ip += 4;
345			ref += 4;
346		}
347		#endif
348		if ((ip < (MATCHLIMIT - 1)) && (A16(ref) == A16(ip))) {
349			ip += 2;
350			ref += 2;
351		}
352		if ((ip < MATCHLIMIT) && (*ref == *ip))
353			ip++;
354_endcount:
355
356		/* Encode MatchLength */
357		len = (int)(ip - anchor);
358		/* Check output limit */
359		if (unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend))
360			return 0;
361		if (len >= (int)ML_MASK) {
362			*token += ML_MASK;
363			len -= ML_MASK;
364			for (; len > 509 ; len -= 510) {
365				*op++ = 255;
366				*op++ = 255;
367			}
368			if (len > 254) {
369				len -= 255;
370				*op++ = 255;
371			}
372			*op++ = (u8)len;
373		} else
374			*token += len;
375
376		/* Test end of chunk */
377		if (ip > mflimit) {
378			anchor = ip;
379			break;
380		}
381
382		/* Fill table */
383		hashtable[LZ4_HASH64K_VALUE(ip-2)] = (u16)(ip - 2 - base);
384
385		/* Test next position */
386		ref = base + hashtable[LZ4_HASH64K_VALUE(ip)];
387		hashtable[LZ4_HASH64K_VALUE(ip)] = (u16)(ip - base);
388		if (A32(ref) == A32(ip)) {
389			token = op++;
390			*token = 0;
391			goto _next_match;
392		}
393
394		/* Prepare next loop */
395		anchor = ip++;
396		forwardh = LZ4_HASH64K_VALUE(ip);
397	}
398
399_last_literals:
400	/* Encode Last Literals */
401	lastrun = (int)(iend - anchor);
402	if (op + lastrun + 1 + (lastrun - RUN_MASK + 255) / 255 > oend)
403		return 0;
404	if (lastrun >= (int)RUN_MASK) {
405		*op++ = (RUN_MASK << ML_BITS);
406		lastrun -= RUN_MASK;
407		for (; lastrun > 254 ; lastrun -= 255)
408			*op++ = 255;
409		*op++ = (u8)lastrun;
410	} else
411		*op++ = (lastrun << ML_BITS);
412	memcpy(op, anchor, iend - anchor);
413	op += iend - anchor;
414	/* End */
415	return (int)(((char *)op) - dest);
416}
417
418int lz4_compress(const unsigned char *src, size_t src_len,
419			unsigned char *dst, size_t *dst_len, void *wrkmem)
420{
421	int ret = -1;
422	int out_len = 0;
423
424	if (src_len < LZ4_64KLIMIT)
425		out_len = lz4_compress64kctx(wrkmem, src, dst, src_len,
426				lz4_compressbound(src_len));
427	else
428		out_len = lz4_compressctx(wrkmem, src, dst, src_len,
429				lz4_compressbound(src_len));
430
431	if (out_len < 0)
432		goto exit;
433
434	*dst_len = out_len;
435
436	return 0;
437exit:
438	return ret;
439}
440EXPORT_SYMBOL(lz4_compress);
441
442MODULE_LICENSE("Dual BSD/GPL");
443MODULE_DESCRIPTION("LZ4 compressor");
444