File: lzo1x_c.c

package info (click to toggle)
busybox 1:1.22.0-19
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 16,504 kB
  • sloc: ansic: 187,199; sh: 6,812; cpp: 1,428; makefile: 1,052; yacc: 570; lex: 355; perl: 312; python: 255; awk: 29
file content (296 lines) | stat: -rw-r--r-- 7,045 bytes parent folder | download | duplicates (3)
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
/* implementation of the LZO1[XY]-1 compression algorithm

   This file is part of the LZO real-time data compression library.

   Copyright (C) 1996..2008 Markus Franz Xaver Johannes Oberhumer
   All Rights Reserved.

   Markus F.X.J. Oberhumer <markus@oberhumer.com>
   http://www.oberhumer.com/opensource/lzo/

   The LZO library is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of
   the License, or (at your option) any later version.

   The LZO library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with the LZO library; see the file COPYING.
   If not, write to the Free Software Foundation, Inc.,
   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

/***********************************************************************
// compress a block of data.
************************************************************************/
static NOINLINE unsigned
do_compress(const uint8_t* in, unsigned in_len,
		uint8_t* out, unsigned* out_len,
		void* wrkmem)
{
	register const uint8_t* ip;
	uint8_t* op;
	const uint8_t* const in_end = in + in_len;
	const uint8_t* const ip_end = in + in_len - M2_MAX_LEN - 5;
	const uint8_t* ii;
	const void* *const dict = (const void**) wrkmem;

	op = out;
	ip = in;
	ii = ip;

	ip += 4;
	for (;;) {
		register const uint8_t* m_pos;
		unsigned m_off;
		unsigned m_len;
		unsigned dindex;

		D_INDEX1(dindex,ip);
		GINDEX(m_pos,m_off,dict,dindex,in);
		if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
			goto literal;
#if 1
		if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
			goto try_match;
		D_INDEX2(dindex,ip);
#endif
		GINDEX(m_pos,m_off,dict,dindex,in);
		if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
			goto literal;
		if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
			goto try_match;
		goto literal;

 try_match:
#if 1 && defined(LZO_UNALIGNED_OK_2)
		if (* (const lzo_ushortp) m_pos != * (const lzo_ushortp) ip)
#else
		if (m_pos[0] != ip[0] || m_pos[1] != ip[1])
#endif
		{
		} else {
			if (m_pos[2] == ip[2]) {
#if 0
				if (m_off <= M2_MAX_OFFSET)
					goto match;
				if (lit <= 3)
					goto match;
				if (lit == 3) {			  /* better compression, but slower */
					assert(op - 2 > out); op[-2] |= (uint8_t)(3);
					*op++ = *ii++; *op++ = *ii++; *op++ = *ii++;
					goto code_match;
				}
				if (m_pos[3] == ip[3])
#endif
					goto match;
			}
			else {
				/* still need a better way for finding M1 matches */
#if 0
				/* a M1 match */
#if 0
				if (m_off <= M1_MAX_OFFSET && lit > 0 && lit <= 3)
#else
				if (m_off <= M1_MAX_OFFSET && lit == 3)
#endif
				{
					register unsigned t;

					t = lit;
					assert(op - 2 > out); op[-2] |= (uint8_t)(t);
					do *op++ = *ii++; while (--t > 0);
					assert(ii == ip);
					m_off -= 1;
					*op++ = (uint8_t)(M1_MARKER | ((m_off & 3) << 2));
					*op++ = (uint8_t)(m_off >> 2);
					ip += 2;
					goto match_done;
				}
#endif
			}
		}

		/* a literal */
 literal:
		UPDATE_I(dict, 0, dindex, ip, in);
		++ip;
		if (ip >= ip_end)
			break;
		continue;

		/* a match */
match:
		UPDATE_I(dict, 0, dindex, ip, in);
		/* store current literal run */
		if (pd(ip, ii) > 0) {
			register unsigned t = pd(ip, ii);

			if (t <= 3) {
				assert(op - 2 > out);
				op[-2] |= (uint8_t)(t);
			}
			else if (t <= 18)
				*op++ = (uint8_t)(t - 3);
			else {
				register unsigned tt = t - 18;

				*op++ = 0;
				while (tt > 255) {
					tt -= 255;
					*op++ = 0;
				}
				assert(tt > 0);
				*op++ = (uint8_t)(tt);
			}
			do *op++ = *ii++; while (--t > 0);
		}

		/* code the match */
		assert(ii == ip);
		ip += 3;
		if (m_pos[3] != *ip++ || m_pos[4] != *ip++ || m_pos[5] != *ip++
		 || m_pos[6] != *ip++ || m_pos[7] != *ip++ || m_pos[8] != *ip++
#ifdef LZO1Y
		 || m_pos[ 9] != *ip++ || m_pos[10] != *ip++ || m_pos[11] != *ip++
		 || m_pos[12] != *ip++ || m_pos[13] != *ip++ || m_pos[14] != *ip++
#endif
		) {
			--ip;
			m_len = pd(ip, ii);
			assert(m_len >= 3);
			assert(m_len <= M2_MAX_LEN);

			if (m_off <= M2_MAX_OFFSET) {
				m_off -= 1;
#if defined(LZO1X)
				*op++ = (uint8_t)(((m_len - 1) << 5) | ((m_off & 7) << 2));
				*op++ = (uint8_t)(m_off >> 3);
#elif defined(LZO1Y)
				*op++ = (uint8_t)(((m_len + 1) << 4) | ((m_off & 3) << 2));
				*op++ = (uint8_t)(m_off >> 2);
#endif
			}
			else if (m_off <= M3_MAX_OFFSET) {
				m_off -= 1;
				*op++ = (uint8_t)(M3_MARKER | (m_len - 2));
				goto m3_m4_offset;
			} else {
#if defined(LZO1X)
				m_off -= 0x4000;
				assert(m_off > 0);
				assert(m_off <= 0x7fff);
				*op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
				goto m3_m4_offset;
#elif defined(LZO1Y)
				goto m4_match;
#endif
			}
		}
		else {
			{
				const uint8_t* end = in_end;
				const uint8_t* m = m_pos + M2_MAX_LEN + 1;
				while (ip < end && *m == *ip)
					m++, ip++;
				m_len = pd(ip, ii);
			}
			assert(m_len > M2_MAX_LEN);

			if (m_off <= M3_MAX_OFFSET) {
				m_off -= 1;
				if (m_len <= 33)
					*op++ = (uint8_t)(M3_MARKER | (m_len - 2));
				else {
					m_len -= 33;
					*op++ = M3_MARKER | 0;
					goto m3_m4_len;
				}
			} else {
#if defined(LZO1Y)
 m4_match:
#endif
				m_off -= 0x4000;
				assert(m_off > 0);
				assert(m_off <= 0x7fff);
				if (m_len <= M4_MAX_LEN)
					*op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
				else {
					m_len -= M4_MAX_LEN;
					*op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11));
 m3_m4_len:
					while (m_len > 255) {
						m_len -= 255;
						*op++ = 0;
					}
					assert(m_len > 0);
					*op++ = (uint8_t)(m_len);
				}
			}
 m3_m4_offset:
			*op++ = (uint8_t)((m_off & 63) << 2);
			*op++ = (uint8_t)(m_off >> 6);
		}
#if 0
 match_done:
#endif
		ii = ip;
		if (ip >= ip_end)
			break;
	}

	*out_len = pd(op, out);
	return pd(in_end, ii);
}

/***********************************************************************
// public entry point
************************************************************************/
int DO_COMPRESS(const uint8_t* in, unsigned in_len,
		uint8_t* out, unsigned* out_len,
		void* wrkmem)
{
	uint8_t* op = out;
	unsigned t;

	if (in_len <= M2_MAX_LEN + 5)
		t = in_len;
	else {
		t = do_compress(in,in_len,op,out_len,wrkmem);
		op += *out_len;
	}

	if (t > 0) {
		const uint8_t* ii = in + in_len - t;

		if (op == out && t <= 238)
			*op++ = (uint8_t)(17 + t);
		else if (t <= 3)
			op[-2] |= (uint8_t)(t);
		else if (t <= 18)
			*op++ = (uint8_t)(t - 3);
		else {
			unsigned tt = t - 18;

			*op++ = 0;
			while (tt > 255) {
				tt -= 255;
				*op++ = 0;
			}
			assert(tt > 0);
			*op++ = (uint8_t)(tt);
		}
		do *op++ = *ii++; while (--t > 0);
	}

	*op++ = M4_MARKER | 1;
	*op++ = 0;
	*op++ = 0;

	*out_len = pd(op, out);
	return 0; /*LZO_E_OK*/
}