/*
* Copyright (c) 2000-2007 Marc Alexander Lehmann <[email protected]>
*
* 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.
*/

#if defined(_KERNEL) || defined (_STANDALONE)
#include <lib/libkern/libkern.h>
#include <sys/systm.h>
#include "lzfP.h"
#else
#include "lzf.h"
#endif

#ifdef _KERNEL
# define SET_ERRNO(n) panic("lzf decompression failure: %s", #n)
#else
# ifdef AVOID_ERRNO
#  define SET_ERRNO(n)
# else
#  include <errno.h>
#  define SET_ERRNO(n) errno = (n)
# endif
#endif

#if (__i386 || __amd64) && __GNUC__ >= 3
# define lzf_movsb(dst, src, len)                \
  asm ("rep movsb"                              \
       : "=D" (dst), "=S" (src), "=c" (len)     \
       :  "0" (dst),  "1" (src),  "2" (len));
#endif

unsigned int
lzf_decompress (const void *const in_data,  unsigned int in_len,
               void             *out_data, unsigned int out_len)
{
 u8 const *ip = (const u8 *)in_data;
 u8       *op = (u8 *)out_data;
 u8 const *const in_end  = ip + in_len;
 u8       *const out_end = op + out_len;

 do
   {
     unsigned int ctrl = *ip++;

     if (ctrl < (1 << 5)) /* literal run */
       {
         ctrl++;

         if (op + ctrl > out_end)
           {
             SET_ERRNO (E2BIG);
             return 0;
           }

#if CHECK_INPUT
         if (ip + ctrl > in_end)
           {
             SET_ERRNO (EINVAL);
             return 0;
           }
#endif

#ifdef lzf_movsb
         lzf_movsb (op, ip, ctrl);
#else
         do
           *op++ = *ip++;
         while (--ctrl);
#endif
       }
     else /* back reference */
       {
         unsigned int len = ctrl >> 5;

         u8 *ref = op - ((ctrl & 0x1f) << 8) - 1;

#if CHECK_INPUT
         if (ip >= in_end)
           {
             SET_ERRNO (EINVAL);
             return 0;
           }
#endif
         if (len == 7)
           {
             len += *ip++;
#if CHECK_INPUT
             if (ip >= in_end)
               {
                 SET_ERRNO (EINVAL);
                 return 0;
               }
#endif
           }

         ref -= *ip++;

         if (op + len + 2 > out_end)
           {
             SET_ERRNO (E2BIG);
             return 0;
           }

         if (ref < (u8 *)out_data)
           {
             SET_ERRNO (EINVAL);
             return 0;
           }

#ifdef lzf_movsb
         len += 2;
         lzf_movsb (op, ref, len);
#else
         *op++ = *ref++;
         *op++ = *ref++;

         do
           *op++ = *ref++;
         while (--len);
#endif
       }
   }
 while (ip < in_end);

 return (unsigned)(op - (u8 *)out_data);
}