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/* n2e_d.c -- implementation of the NRV2E decompression algorithm

   This file is part of the UCL data compression library.

   Copyright (C) 1996-2004 Markus Franz Xaver Johannes Oberhumer

   All Rights Reserved.

   The UCL 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 UCL 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 UCL library; see the file COPYING.

   If not, write to the Free Software Foundation, Inc.,

   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   Markus F.X.J. Oberhumer

   <markus@oberhumer.com>

   http://www.oberhumer.com/opensource/ucl/

 */

/***********************************************************************

// actual implementation used by a recursive #include

************************************************************************/

#ifdef getbit

#ifdef SAFE

#define fail(x,r)   if (x) { *dst_len = olen; return r; }

#else

#define fail(x,r)

#endif

{

    ucl_uint32 bb = 0;

#ifdef TEST_OVERLAP

    ucl_uint ilen = src_off, olen = 0, last_m_off = 1;

#else

    ucl_uint ilen = 0, olen = 0, last_m_off = 1;

#endif

#ifdef SAFE

    const ucl_uint oend = *dst_len;

#endif

    ACC_UNUSED(wrkmem);

#ifdef TEST_OVERLAP

    src_len += src_off;

    fail(oend >= src_len, UCL_E_OVERLAP_OVERRUN);

#endif

    for (;;)

    {

        ucl_uint m_off, m_len;

        while (getbit(bb))

        {

            fail(ilen >= src_len, UCL_E_INPUT_OVERRUN);

            fail(olen >= oend, UCL_E_OUTPUT_OVERRUN);

#ifdef TEST_OVERLAP

            fail(olen > ilen, UCL_E_OVERLAP_OVERRUN);

            olen++; ilen++;

#else

            dst[olen++] = src[ilen++];

#endif

        }

        m_off = 1;

        for (;;)

        {

            m_off = m_off*2 + getbit(bb);

            fail(ilen >= src_len, UCL_E_INPUT_OVERRUN);

            fail(m_off > UCL_UINT32_C(0xffffff) + 3, UCL_E_LOOKBEHIND_OVERRUN);

            if (getbit(bb)) break;

            m_off = (m_off-1)*2 + getbit(bb);

        }

        if (m_off == 2)

        {

            m_off = last_m_off;

            m_len = getbit(bb);

        }

        else

        {

            fail(ilen >= src_len, UCL_E_INPUT_OVERRUN);

            m_off = (m_off-3)*256 + src[ilen++];

            if (m_off == UCL_UINT32_C(0xffffffff))

                break;

            m_len = (m_off ^ UCL_UINT32_C(0xffffffff)) & 1;

            m_off >>= 1;

            last_m_off = ++m_off;

        }

        if (m_len)

            m_len = 1 + getbit(bb);

        else if (getbit(bb))

            m_len = 3 + getbit(bb);

        else

        {

            m_len++;

            do {

                m_len = m_len*2 + getbit(bb);

                fail(ilen >= src_len, UCL_E_INPUT_OVERRUN);

                fail(m_len >= oend, UCL_E_OUTPUT_OVERRUN);

            } while (!getbit(bb));

            m_len += 3;

        }

        m_len += (m_off > 0x500);

        fail(olen + m_len > oend, UCL_E_OUTPUT_OVERRUN);

        fail(m_off > olen, UCL_E_LOOKBEHIND_OVERRUN);

#ifdef TEST_OVERLAP

        olen += m_len + 1;

        fail(olen > ilen, UCL_E_OVERLAP_OVERRUN);

#else

        {

            const ucl_bytep m_pos;

            m_pos = dst + olen - m_off;

            dst[olen++] = *m_pos++;

            do dst[olen++] = *m_pos++; while (--m_len > 0);

        }

#endif

    }

    *dst_len = olen;

    return ilen == src_len ? UCL_E_OK : (ilen < src_len ? UCL_E_INPUT_NOT_CONSUMED : UCL_E_INPUT_OVERRUN);

}

#undef fail

#endif /* getbit */

/***********************************************************************

// decompressor entries for the different bit-buffer sizes

************************************************************************/

#ifndef getbit

#include "ucl_conf.h"

#include <ucl/ucl.h>

#include "getbit.h"

UCL_PUBLIC(int)

ucl_nrv2e_decompress_8          ( const ucl_bytep src, ucl_uint  src_len,

                                        ucl_bytep dst, ucl_uintp dst_len,

                                        ucl_voidp wrkmem )

{

#define getbit(bb)      getbit_8(bb,src,ilen)

#include "n2e_d.c"

#undef getbit

}

UCL_PUBLIC(int)

ucl_nrv2e_decompress_le16       ( const ucl_bytep src, ucl_uint  src_len,

                                        ucl_bytep dst, ucl_uintp dst_len,

                                        ucl_voidp wrkmem )

{

#define getbit(bb)      getbit_le16(bb,src,ilen)

#include "n2e_d.c"

#undef getbit

}

UCL_PUBLIC(int)

ucl_nrv2e_decompress_le32       ( const ucl_bytep src, ucl_uint  src_len,

                                        ucl_bytep dst, ucl_uintp dst_len,

                                        ucl_voidp wrkmem )

{

    unsigned bc = 0;

#define getbit(bb)      getbit_le32(bb,bc,src,ilen)

#include "n2e_d.c"

#undef getbit

}

#endif /* !getbit */

/*

vi:ts=4:et

*/