/* lzo1f_1.c -- implementation of the LZO1F-1 compression algorithm

   This file is part of the LZO real-time data compression library.

   Copyright (C) 1996-2017 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: */