1/*
2 *  LZO1X Compressor from MiniLZO
3 *
4 *  Copyright (C) 1996-2005 Markus F.X.J. Oberhumer <markus@oberhumer.com>
5 *
6 *  The full LZO package can be found at:
7 *  http://www.oberhumer.com/opensource/lzo/
8 *
9 *  Changed for kernel use by:
10 *  Nitin Gupta <nitingupta910@gmail.com>
11 *  Richard Purdie <rpurdie@openedhand.com>
12 */
13
14#include <linux/module.h>
15#include <linux/kernel.h>
16#include <linux/lzo.h>
17#include <asm/unaligned.h>
18#include "lzodefs.h"
19
20static noinline size_t
21_lzo1x_1_do_compress(const unsigned char *in, size_t in_len,
22		unsigned char *out, size_t *out_len, void *wrkmem)
23{
24	const unsigned char * const in_end = in + in_len;
25	const unsigned char * const ip_end = in + in_len - M2_MAX_LEN - 5;
26	const unsigned char ** const dict = wrkmem;
27	const unsigned char *ip = in, *ii = ip;
28	const unsigned char *end, *m, *m_pos;
29	size_t m_off, m_len, dindex;
30	unsigned char *op = out;
31
32	ip += 4;
33
34	for (;;) {
35		dindex = ((size_t)(0x21 * DX3(ip, 5, 5, 6)) >> 5) & D_MASK;
36		m_pos = dict[dindex];
37
38		if (m_pos < in)
39			goto literal;
40
41		if (ip == m_pos || ((size_t)(ip - m_pos) > M4_MAX_OFFSET))
42			goto literal;
43
44		m_off = ip - m_pos;
45		if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
46			goto try_match;
47
48		dindex = (dindex & (D_MASK & 0x7ff)) ^ (D_HIGH | 0x1f);
49		m_pos = dict[dindex];
50
51		if (m_pos < in)
52			goto literal;
53
54		if (ip == m_pos || ((size_t)(ip - m_pos) > M4_MAX_OFFSET))
55			goto literal;
56
57		m_off = ip - m_pos;
58		if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
59			goto try_match;
60
61		goto literal;
62
63try_match:
64		if (get_unaligned((const unsigned short *)m_pos)
65				== get_unaligned((const unsigned short *)ip)) {
66			if (likely(m_pos[2] == ip[2]))
67					goto match;
68		}
69
70literal:
71		dict[dindex] = ip;
72		++ip;
73		if (unlikely(ip >= ip_end))
74			break;
75		continue;
76
77match:
78		dict[dindex] = ip;
79		if (ip != ii) {
80			size_t t = ip - ii;
81
82			if (t <= 3) {
83				op[-2] |= t;
84			} else if (t <= 18) {
85				*op++ = (t - 3);
86			} else {
87				size_t tt = t - 18;
88
89				*op++ = 0;
90				while (tt > 255) {
91					tt -= 255;
92					*op++ = 0;
93				}
94				*op++ = tt;
95			}
96			do {
97				*op++ = *ii++;
98			} while (--t > 0);
99		}
100
101		ip += 3;
102		if (m_pos[3] != *ip++ || m_pos[4] != *ip++
103				|| m_pos[5] != *ip++ || m_pos[6] != *ip++
104				|| m_pos[7] != *ip++ || m_pos[8] != *ip++) {
105			--ip;
106			m_len = ip - ii;
107
108			if (m_off <= M2_MAX_OFFSET) {
109				m_off -= 1;
110				*op++ = (((m_len - 1) << 5)
111						| ((m_off & 7) << 2));
112				*op++ = (m_off >> 3);
113			} else if (m_off <= M3_MAX_OFFSET) {
114				m_off -= 1;
115				*op++ = (M3_MARKER | (m_len - 2));
116				goto m3_m4_offset;
117			} else {
118				m_off -= 0x4000;
119
120				*op++ = (M4_MARKER | ((m_off & 0x4000) >> 11)
121						| (m_len - 2));
122				goto m3_m4_offset;
123			}
124		} else {
125			end = in_end;
126			m = m_pos + M2_MAX_LEN + 1;
127
128			while (ip < end && *m == *ip) {
129				m++;
130				ip++;
131			}
132			m_len = ip - ii;
133
134			if (m_off <= M3_MAX_OFFSET) {
135				m_off -= 1;
136				if (m_len <= 33) {
137					*op++ = (M3_MARKER | (m_len - 2));
138				} else {
139					m_len -= 33;
140					*op++ = M3_MARKER | 0;
141					goto m3_m4_len;
142				}
143			} else {
144				m_off -= 0x4000;
145				if (m_len <= M4_MAX_LEN) {
146					*op++ = (M4_MARKER
147						| ((m_off & 0x4000) >> 11)
148						| (m_len - 2));
149				} else {
150					m_len -= M4_MAX_LEN;
151					*op++ = (M4_MARKER
152						| ((m_off & 0x4000) >> 11));
153m3_m4_len:
154					while (m_len > 255) {
155						m_len -= 255;
156						*op++ = 0;
157					}
158
159					*op++ = (m_len);
160				}
161			}
162m3_m4_offset:
163			*op++ = ((m_off & 63) << 2);
164			*op++ = (m_off >> 6);
165		}
166
167		ii = ip;
168		if (unlikely(ip >= ip_end))
169			break;
170	}
171
172	*out_len = op - out;
173	return in_end - ii;
174}
175
176int lzo1x_1_compress(const unsigned char *in, size_t in_len, unsigned char *out,
177			size_t *out_len, void *wrkmem)
178{
179	const unsigned char *ii;
180	unsigned char *op = out;
181	size_t t;
182
183	if (unlikely(in_len <= M2_MAX_LEN + 5)) {
184		t = in_len;
185	} else {
186		t = _lzo1x_1_do_compress(in, in_len, op, out_len, wrkmem);
187		op += *out_len;
188	}
189
190	if (t > 0) {
191		ii = in + in_len - t;
192
193		if (op == out && t <= 238) {
194			*op++ = (17 + t);
195		} else if (t <= 3) {
196			op[-2] |= t;
197		} else if (t <= 18) {
198			*op++ = (t - 3);
199		} else {
200			size_t tt = t - 18;
201
202			*op++ = 0;
203			while (tt > 255) {
204				tt -= 255;
205				*op++ = 0;
206			}
207
208			*op++ = tt;
209		}
210		do {
211			*op++ = *ii++;
212		} while (--t > 0);
213	}
214
215	*op++ = M4_MARKER | 1;
216	*op++ = 0;
217	*op++ = 0;
218
219	*out_len = op - out;
220	return LZO_E_OK;
221}
222EXPORT_SYMBOL_GPL(lzo1x_1_compress);
223
224MODULE_LICENSE("GPL");
225MODULE_DESCRIPTION("LZO1X-1 Compressor");
226