/* 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*/ }