text: /* lzo1f_1.c -- implementation of the LZO1F-1 compression algorithm
  
     This file is part of the LZO real-time data compression library.
  
     Copyright (C) 1996-2015 Markus Franz Xaver Johannes Oberhumer
     All Rights Reserved.
  
     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.
  
     Markus F.X.J. Oberhumer
     <markus@oberhumer.com>
     http://www.oberhumer.com/opensource/lzo/
   */
  
  
  #include "lzo_conf.h"
  #include <lzo/lzo1f.h>
  
  
  /***********************************************************************
  //
  ************************************************************************/
  
  #define M2_MAX_OFFSET   0x0800
  #define M3_MAX_OFFSET   0x3fff
  #define M3_MARKER       224
  
  
  #ifndef LZO_HASH
  #define LZO_HASH        LZO_HASH_LZO_INCREMENTAL_A
  #endif
  #define D_BITS          14
  #define D_INDEX1(d,p)   d = DM(DMUL(0x21,DX3(p,5,5,6)) >> 5)
  #define D_INDEX2(d,p)   d = (d & (D_MASK & 0x7ff)) ^ (D_HIGH | 0x1f)
  #include "lzo_dict.h"
  
  
  /***********************************************************************
  // compress a block of data.
  ************************************************************************/
  
  static __lzo_noinline
  int do_compress          ( const lzo_bytep in , lzo_uint  in_len,
                                   lzo_bytep out, lzo_uintp out_len,
                                   lzo_voidp wrkmem )
  {
      const lzo_bytep ip;
      lzo_bytep op;
      const lzo_bytep const in_end = in + in_len;
      const lzo_bytep const ip_end = in + in_len - 9;
      const lzo_bytep ii;
      lzo_dict_p const dict = (lzo_dict_p) wrkmem;
  
      op = out;
      ip = in;
      ii = ip;
  
      ip++;
      for (;;)
      {
          const lzo_bytep m_pos;
          LZO_DEFINE_UNINITIALIZED_VAR(lzo_uint, m_off, 0);
          lzo_uint m_len;
          lzo_uint dindex;
          lzo_uint lit;
  
          DINDEX1(dindex,ip);
          GINDEX(m_pos,m_off,dict,dindex,in);
          if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M3_MAX_OFFSET))
              goto literal;
  #if 1
          if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
              goto try_match;
          DINDEX2(dindex,ip);
  #endif
          GINDEX(m_pos,m_off,dict,dindex,in);
          if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M3_MAX_OFFSET))
              goto literal;
          if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
              goto try_match;
          goto literal;
  
  
  try_match:
  #if 0 && (LZO_OPT_UNALIGNED16)
          if (UA_GET_NE16(m_pos) != UA_GET_NE16(ip))
  #else
          if (m_pos[0] != ip[0] || m_pos[1] != ip[1])
  #endif
          {
          }
          else
          {
              if (m_pos[2] == ip[2])
              {
                  m_pos += 3;
  #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] |= LZO_BYTE(3);
                      *op++ = *ii++; *op++ = *ii++; *op++ = *ii++;
                      goto code_match;
                  }
                  if (*m_pos == ip[3])
  #endif
                      goto match;
              }
          }
  
  
      /* a literal */
  literal:
          UPDATE_I(dict,0,dindex,ip,in);
          if (++ip >= ip_end)
              break;
          continue;
  
  
      /* a match */
  match:
          UPDATE_I(dict,0,dindex,ip,in);
          /* store current literal run */
          lit = pd(ip,ii);
          if (lit > 0)
          {
              lzo_uint t = lit;
  
              if (t < 4 && op > out)
                  op[-2] = LZO_BYTE(op[-2] | t);
              else if (t <= 31)
                  *op++ = LZO_BYTE(t);
              else
              {
                  lzo_uint tt = t - 31;
  
                  *op++ = 0;
                  while (tt > 255)
                  {
                      tt -= 255;
                      UA_SET1(op, 0);
                      op++;
                  }
                  assert(tt > 0);
                  *op++ = LZO_BYTE(tt);
              }
              do *op++ = *ii++; while (--t > 0);
          }
          assert(ii == ip);
  
  
          /* code the match */
          ip += 3;
          if (*m_pos++ != *ip++ || *m_pos++ != *ip++ || *m_pos++ != *ip++ ||
              *m_pos++ != *ip++ || *m_pos++ != *ip++ || *m_pos++ != *ip++)
          {
              --ip;
              m_len = pd(ip, ii);
              assert(m_len >= 3); assert(m_len <= 8);
  
              if (m_off <= M2_MAX_OFFSET)
              {
                  m_off -= 1;
                  *op++ = LZO_BYTE(((m_len - 2) << 5) | ((m_off & 7) << 2));
                  *op++ = LZO_BYTE(m_off >> 3);
              }
              else if (m_len == 3 && m_off <= 2*M2_MAX_OFFSET && lit > 0)
              {
                  m_off -= 1;
                  /* m_off -= M2_MAX_OFFSET; */
                  *op++ = LZO_BYTE(((m_off & 7) << 2));
                  *op++ = LZO_BYTE(m_off >> 3);
              }
              else
              {
                  *op++ = LZO_BYTE(M3_MARKER | (m_len - 2));
                  *op++ = LZO_BYTE((m_off & 63) << 2);
                  *op++ = LZO_BYTE(m_off >> 6);
              }
          }
          else
          {
              {
                  const lzo_bytep end;
                  end = in_end;
                  while (ip < end && *m_pos == *ip)
                      m_pos++, ip++;
                  m_len = pd(ip, ii);
              }
              assert(m_len >= 3);
  
              if (m_len <= 33)
                  *op++ = LZO_BYTE(M3_MARKER | (m_len - 2));
              else
              {
                  m_len -= 33;
                  *op++ = M3_MARKER | 0;
                  while (m_len > 255)
                  {
                      m_len -= 255;
                      UA_SET1(op, 0);
                      op++;
                  }
                  assert(m_len > 0);
                  *op++ = LZO_BYTE(m_len);
              }
              *op++ = LZO_BYTE((m_off & 63) << 2);
              *op++ = LZO_BYTE(m_off >> 6);
          }
  
          ii = ip;
          if (ip >= ip_end)
              break;
      }
  
  
      /* store final literal run */
      if (pd(in_end,ii) > 0)
      {
          lzo_uint t = pd(in_end,ii);
  
          if (t < 4 && op > out)
              op[-2] = LZO_BYTE(op[-2] | t);
          else if (t <= 31)
              *op++ = LZO_BYTE(t);
          else
          {
              lzo_uint tt = t - 31;
  
              *op++ = 0;
              while (tt > 255)
              {
                  tt -= 255;
                  UA_SET1(op, 0);
                  op++;
              }
              assert(tt > 0);
              *op++ = LZO_BYTE(tt);
          }
          UA_COPYN(op, ii, t);
          op += t;
      }
  
      *out_len = pd(op, out);
      return LZO_E_OK;
  }
  
  
  /***********************************************************************
  // public entry point
  ************************************************************************/
  
  LZO_PUBLIC(int)
  lzo1f_1_compress ( const lzo_bytep in , lzo_uint  in_len,
                           lzo_bytep out, lzo_uintp out_len,
                           lzo_voidp wrkmem )
  {
      lzo_bytep op = out;
      int r = LZO_E_OK;
  
      if (in_len == 0)
          *out_len = 0;
      else if (in_len <= 10)
      {
          *op++ = LZO_BYTE(in_len);
          do *op++ = *in++; while (--in_len > 0);
          *out_len = pd(op, out);
      }
      else
          r = do_compress(in,in_len,out,out_len,wrkmem);
  
      if (r == LZO_E_OK)
      {
          op = out + *out_len;
          op[0] = M3_MARKER | 1;
          op[1] = 0;
          op[2] = 0;
          *out_len += 3;
      }
  
      return r;
  }
  
  
  /* vim:set ts=4 sw=4 et: */
  