text: /*
   * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
   * 
   * Redistribution and use in source and binary forms, with or without modifica-
   * tion, are permitted provided that the following conditions are met:
   * 
   *   1.  Redistributions of source code must retain the above copyright notice,
   *       this list of conditions and the following disclaimer.
   * 
   *   2.  Redistributions in binary form must reproduce the above copyright
   *       notice, this list of conditions and the following disclaimer in the
   *       documentation and/or other materials provided with the distribution.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
   * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
   * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
   * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
   * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
   * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * Alternatively, the contents of this file may be used under the terms of
   * the GNU General Public License ("GPL") version 2 or any later version,
   * in which case the provisions of the GPL are applicable instead of
   * the above. If you wish to allow the use of your version of this file
   * only under the terms of the GPL and not to allow others to use your
   * version of this file under the BSD license, indicate your decision
   * by deleting the provisions above and replace them with the notice
   * and other provisions required by the GPL. If you do not delete the
   * provisions above, a recipient may use your version of this file under
   * either the BSD or the GPL.
   */
  
  #include "lzfP.h"
  
  #define HSIZE (1 << (HLOG))
  
  /*
   * don't play with this unless you benchmark!
   * decompression is not dependent on the hash function
   * the hashing function might seem strange, just believe me
   * it works ;)
   */
  #ifndef FRST
  # define FRST(p) (((p[0]) << 8) | p[1])
  # define NEXT(v,p) (((v) << 8) | p[2])
  # if ULTRA_FAST
  #  define IDX(h) ((( h             >> (3*8 - HLOG)) - h  ) & (HSIZE - 1))
  # elif VERY_FAST
  #  define IDX(h) ((( h             >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
  # else
  #  define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
  # endif
  #endif
  /*
   * IDX works because it is very similar to a multiplicative hash, e.g.
   * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
   * the latter is also quite fast on newer CPUs, and compresses similarly.
   *
   * the next one is also quite good, albeit slow ;)
   * (int)(cos(h & 0xffffff) * 1e6)
   */
  
  #if 0
  /* original lzv-like hash function, much worse and thus slower */
  # define FRST(p) (p[0] << 5) ^ p[1]
  # define NEXT(v,p) ((v) << 5) ^ p[2]
  # define IDX(h) ((h) & (HSIZE - 1))
  #endif
  
  #define        MAX_LIT        (1 <<  5)
  #define        MAX_OFF        (1 << 13)
  #define        MAX_REF        ((1 << 8) + (1 << 3))
  
  #if __GNUC__ >= 3
  # define expect(expr,value)         __builtin_expect ((expr),(value))
  # define inline                     inline
  #else
  # define expect(expr,value)         (expr)
  # define inline                     static
  #endif
  
  #define expect_false(expr) expect ((expr) != 0, 0)
  #define expect_true(expr)  expect ((expr) != 0, 1)
  
  /*
   * compressed format
   *
   * 000LLLLL <L+1>    ; literal
   * LLLooooo oooooooo ; backref L
   * 111ooooo LLLLLLLL oooooooo ; backref L+7
   *
   */
  
  /*
   * lzf 压缩算法
   */
  unsigned int
  lzf_compress (const void *const in_data, unsigned int in_len,
  	      void *out_data, unsigned int out_len
  #if LZF_STATE_ARG
                , LZF_STATE htab
  #endif
                )
  {
  #if !LZF_STATE_ARG
    LZF_STATE htab;
  #endif
    const u8 **hslot;
    const u8 *ip = (const u8 *)in_data;
          u8 *op = (u8 *)out_data;
    const u8 *in_end  = ip + in_len;
          u8 *out_end = op + out_len;
    const u8 *ref;
  
    /* off requires a type wide enough to hold a general pointer difference.
     * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
     * works for differences within a single object). We also assume that no
     * no bit pattern traps. Since the only platform that is both non-POSIX
     * and fails to support both assumptions is windows 64 bit, we make a
     * special workaround for it.
     */
  #if defined (WIN32) && defined (_M_X64)
    unsigned _int64 off; /* workaround for missing POSIX compliance */
  #else
    unsigned long off;
  #endif
    unsigned int hval;
    int lit;
  
    if (!in_len || !out_len)
      return 0;
  
  #if INIT_HTAB
    memset (htab, 0, sizeof (htab));
  # if 0
    for (hslot = htab; hslot < htab + HSIZE; hslot++)
      *hslot++ = ip;
  # endif
  #endif
  
    lit = 0; op++; /* start run */
  
    hval = FRST (ip);
    while (ip < in_end - 2)
      {
        hval = NEXT (hval, ip);
        hslot = htab + IDX (hval);
        ref = *hslot; *hslot = ip;
  
        if (1
  #if INIT_HTAB
            && ref < ip /* the next test will actually take care of this, but this is faster */
  #endif
            && (off = ip - ref - 1) < MAX_OFF
            && ip + 4 < in_end
            && ref > (u8 *)in_data
  #if STRICT_ALIGN
            && ref[0] == ip[0]
            && ref[1] == ip[1]
            && ref[2] == ip[2]
  #else
            && *(u16 *)ref == *(u16 *)ip
            && ref[2] == ip[2]
  #endif
          )
          {
            /* match found at *ref++ */
            unsigned int len = 2;
            unsigned int maxlen = in_end - ip - len;
            maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
  
            op [- lit - 1] = lit - 1; /* stop run */
            op -= !lit; /* undo run if length is zero */
  
            if (expect_false (op + 3 + 1 >= out_end))
              return 0;
  
            for (;;)
              {
                if (expect_true (maxlen > 16))
                  {
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
  
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
  
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
  
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
                    len++; if (ref [len] != ip [len]) break;
                  }
  
                do
                  len++;
                while (len < maxlen && ref[len] == ip[len]);
  
                break;
              }
  
            len -= 2; /* len is now #octets - 1 */
            ip++;
  
            if (len < 7)
              {
                *op++ = (off >> 8) + (len << 5);
              }
            else
              {
                *op++ = (off >> 8) + (  7 << 5);
                *op++ = len - 7;
              }
  
            *op++ = off;
            lit = 0; op++; /* start run */
  
            ip += len + 1;
  
            if (expect_false (ip >= in_end - 2))
              break;
  
  #if ULTRA_FAST || VERY_FAST
            --ip;
  # if VERY_FAST && !ULTRA_FAST
            --ip;
  # endif
            hval = FRST (ip);
  
            hval = NEXT (hval, ip);
            htab[IDX (hval)] = ip;
            ip++;
  
  # if VERY_FAST && !ULTRA_FAST
            hval = NEXT (hval, ip);
            htab[IDX (hval)] = ip;
            ip++;
  # endif
  #else
            ip -= len + 1;
  
            do
              {
                hval = NEXT (hval, ip);
                htab[IDX (hval)] = ip;
                ip++;
              }
            while (len--);
  #endif
          }
        else
          {
            /* one more literal byte we must copy */
            if (expect_false (op >= out_end))
              return 0;
  
            lit++; *op++ = *ip++;
  
            if (expect_false (lit == MAX_LIT))
              {
                op [- lit - 1] = lit - 1; /* stop run */
                lit = 0; op++; /* start run */
              }
          }
      }
  
    if (op + 3 > out_end) /* at most 3 bytes can be missing here */
      return 0;
  
    while (ip < in_end)
      {
        lit++; *op++ = *ip++;
  
        if (expect_false (lit == MAX_LIT))
          {
            op [- lit - 1] = lit - 1; /* stop run */
            lit = 0; op++; /* start run */
          }
      }
  
    op [- lit - 1] = lit - 1; /* end run */
    op -= !lit; /* undo run if length is zero */
  
    return op - (u8 *)out_data;
  }
  
  