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

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

   Copyright (C) 2008 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2007 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2006 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1996 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 )
{
    register 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 (;;)
    {
        register const lzo_bytep m_pos;
        lzo_uint m_off;
        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 && defined(LZO_UNALIGNED_OK_2)
        if (* (const lzo_ushortp) m_pos != * (const lzo_ushortp) 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)
        {
            register lzo_uint t = lit;

            if (t < 4 && op > out)
                op[-2] |= LZO_BYTE(t);
            else if (t <= 31)
                *op++ = LZO_BYTE(t);
            else
            {
                register lzo_uint tt = t - 31;

                *op++ = 0;
                while (tt > 255)
                {
                    tt -= 255;
                    *op++ = 0;
                }
                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;
                    *op++ = 0;
                }
                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)
    {
        register lzo_uint t = pd(in_end,ii);

        if (t < 4 && op > out)
            op[-2] |= LZO_BYTE(t);
        else if (t <= 31)
            *op++ = LZO_BYTE(t);
        else
        {
            register lzo_uint tt = t - 31;

            *op++ = 0;
            while (tt > 255)
            {
                tt -= 255;
                *op++ = 0;
            }
            assert(tt > 0);
            *op++ = LZO_BYTE(tt);
        }
        do *op++ = *ii++; while (--t > 0);
    }

    *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++ = M3_MARKER | 1;
        *op++ = 0;
        *op++ = 0;
        *out_len += 3;
    }

    return r;
}


/*
vi:ts=4:et
*/