1 /* implementation of the LZO1[XY]-1 compression algorithm
3 This file is part of the LZO real-time data compression library.
5 Copyright (C) 1996..2008 Markus Franz Xaver Johannes Oberhumer
8 Markus F.X.J. Oberhumer <markus@oberhumer.com>
9 http://www.oberhumer.com/opensource/lzo/
11 The LZO library is free software; you can redistribute it and/or
12 modify it under the terms of the GNU General Public License as
13 published by the Free Software Foundation; either version 2 of
14 the License, or (at your option) any later version.
16 The LZO library is distributed in the hope that it will be useful,
17 but WITHOUT ANY WARRANTY; without even the implied warranty of
18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 GNU General Public License for more details.
21 You should have received a copy of the GNU General Public License
22 along with the LZO library; see the file COPYING.
23 If not, write to the Free Software Foundation, Inc.,
24 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
27 /***********************************************************************
28 // compress a block of data.
29 ************************************************************************/
30 static NOINLINE unsigned
31 do_compress(const uint8_t* in, unsigned in_len,
32 uint8_t* out, unsigned* out_len,
35 register const uint8_t* ip;
37 const uint8_t* const in_end = in + in_len;
38 const uint8_t* const ip_end = in + in_len - M2_MAX_LEN - 5;
40 const void* *const dict = (const void**) wrkmem;
48 register const uint8_t* m_pos;
54 GINDEX(m_pos,m_off,dict,dindex,in);
55 if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
58 if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
62 GINDEX(m_pos,m_off,dict,dindex,in);
63 if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
65 if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
70 #if 1 && defined(LZO_UNALIGNED_OK_2)
71 if (* (const lzo_ushortp) m_pos != * (const lzo_ushortp) ip)
73 if (m_pos[0] != ip[0] || m_pos[1] != ip[1])
77 if (m_pos[2] == ip[2]) {
79 if (m_off <= M2_MAX_OFFSET)
83 if (lit == 3) { /* better compression, but slower */
84 assert(op - 2 > out); op[-2] |= (uint8_t)(3);
85 *op++ = *ii++; *op++ = *ii++; *op++ = *ii++;
88 if (m_pos[3] == ip[3])
93 /* still need a better way for finding M1 matches */
97 if (m_off <= M1_MAX_OFFSET && lit > 0 && lit <= 3)
99 if (m_off <= M1_MAX_OFFSET && lit == 3)
105 assert(op - 2 > out); op[-2] |= (uint8_t)(t);
106 do *op++ = *ii++; while (--t > 0);
109 *op++ = (uint8_t)(M1_MARKER | ((m_off & 3) << 2));
110 *op++ = (uint8_t)(m_off >> 2);
120 UPDATE_I(dict, 0, dindex, ip, in);
128 UPDATE_I(dict, 0, dindex, ip, in);
129 /* store current literal run */
130 if (pd(ip, ii) > 0) {
131 register unsigned t = pd(ip, ii);
134 assert(op - 2 > out);
135 op[-2] |= (uint8_t)(t);
138 *op++ = (uint8_t)(t - 3);
140 register unsigned tt = t - 18;
148 *op++ = (uint8_t)(tt);
150 do *op++ = *ii++; while (--t > 0);
156 if (m_pos[3] != *ip++ || m_pos[4] != *ip++ || m_pos[5] != *ip++
157 || m_pos[6] != *ip++ || m_pos[7] != *ip++ || m_pos[8] != *ip++
159 || m_pos[ 9] != *ip++ || m_pos[10] != *ip++ || m_pos[11] != *ip++
160 || m_pos[12] != *ip++ || m_pos[13] != *ip++ || m_pos[14] != *ip++
166 assert(m_len <= M2_MAX_LEN);
168 if (m_off <= M2_MAX_OFFSET) {
171 *op++ = (uint8_t)(((m_len - 1) << 5) | ((m_off & 7) << 2));
172 *op++ = (uint8_t)(m_off >> 3);
174 *op++ = (uint8_t)(((m_len + 1) << 4) | ((m_off & 3) << 2));
175 *op++ = (uint8_t)(m_off >> 2);
178 else if (m_off <= M3_MAX_OFFSET) {
180 *op++ = (uint8_t)(M3_MARKER | (m_len - 2));
186 assert(m_off <= 0x7fff);
187 *op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
196 const uint8_t* end = in_end;
197 const uint8_t* m = m_pos + M2_MAX_LEN + 1;
198 while (ip < end && *m == *ip)
202 assert(m_len > M2_MAX_LEN);
204 if (m_off <= M3_MAX_OFFSET) {
207 *op++ = (uint8_t)(M3_MARKER | (m_len - 2));
210 *op++ = M3_MARKER | 0;
219 assert(m_off <= 0x7fff);
220 if (m_len <= M4_MAX_LEN)
221 *op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
224 *op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11));
226 while (m_len > 255) {
231 *op++ = (uint8_t)(m_len);
235 *op++ = (uint8_t)((m_off & 63) << 2);
236 *op++ = (uint8_t)(m_off >> 6);
246 *out_len = pd(op, out);
247 return pd(in_end, ii);
250 /***********************************************************************
251 // public entry point
252 ************************************************************************/
253 int DO_COMPRESS(const uint8_t* in, unsigned in_len,
254 uint8_t* out, unsigned* out_len,
260 if (in_len <= M2_MAX_LEN + 5)
263 t = do_compress(in,in_len,op,out_len,wrkmem);
268 const uint8_t* ii = in + in_len - t;
270 if (op == out && t <= 238)
271 *op++ = (uint8_t)(17 + t);
273 op[-2] |= (uint8_t)(t);
275 *op++ = (uint8_t)(t - 3);
277 unsigned tt = t - 18;
285 *op++ = (uint8_t)(tt);
287 do *op++ = *ii++; while (--t > 0);
290 *op++ = M4_MARKER | 1;
294 *out_len = pd(op, out);
295 return 0; /*LZO_E_OK*/