/* lzo1x_oo.ch -- LZO1X compressed data optimizer

   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></markus@oberhumer.com>

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

 */

#define TEST_IP     (ip < ip_end)

#define TEST_OP     (op <= op_end)

#define NO_LIT      LZO_UINT_MAX

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

//

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

static void copy2(lzo_bytep ip, const lzo_bytep m_pos, lzo_uint off)

{

    assert(off > 0);

    ip[0] = m_pos[0];

    if (off == 1)

        ip[1] = m_pos[0];

    else

        ip[1] = m_pos[1];

}

static void copy3(lzo_bytep ip, const lzo_bytep m_pos, lzo_uint off)

{

    assert(off > 0);

    ip[0] = m_pos[0];

    if (off == 1)

    {

        ip[2] = ip[1] = m_pos[0];

    }

    else if (off == 2)

    {

        ip[1] = m_pos[1];

        ip[2] = m_pos[0];

    }

    else

    {

        ip[1] = m_pos[1];

        ip[2] = m_pos[2];

    }

}

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

// optimize a block of data.

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

LZO_PUBLIC(int)

DO_OPTIMIZE          (       lzo_bytep in , lzo_uint  in_len,

                             lzo_bytep out, lzo_uintp out_len,

                             lzo_voidp wrkmem )

{

    lzo_bytep op;

    lzo_bytep ip;

    lzo_uint t;

    lzo_bytep m_pos;

    lzo_bytep const ip_end = in + in_len;

    lzo_bytep const op_end = out + *out_len;

    lzo_bytep litp = NULL;

    lzo_uint lit = 0;

    lzo_uint next_lit = NO_LIT;

    lzo_uint nl;

    unsigned long o_m1_a = 0, o_m1_b = 0, o_m2 = 0, o_m3_a = 0, o_m3_b = 0;

    LZO_UNUSED(wrkmem);

    *out_len = 0;

    op = out;

    ip = in;

    assert(in_len >= 3);

    if (*ip > 17)

    {

        t = *ip++ - 17;

        if (t < 4)

            goto match_next;

        goto first_literal_run;

    }

    assert(*ip < 16 || (*ip == 17 && in_len == 3));

    while (TEST_IP && TEST_OP)

    {

        t = *ip++;

        if (t >= 16)

            goto match;

        /* a literal run */

        litp = ip - 1;

        if (t == 0)

        {

            t = 15;

            while (*ip == 0)

                t += 255, ip++;

            t += *ip++;

        }

        lit = t + 3;

        /* copy literals */

copy_literal_run:

        *op++ = *ip++; *op++ = *ip++; *op++ = *ip++;

first_literal_run:

        do *op++ = *ip++; while (--t > 0);

        t = *ip++;

        if (t >= 16)

            goto match;

#if defined(LZO1X)

        m_pos = op - 1 - 0x800;

#elif defined(LZO1Y)

        m_pos = op - 1 - 0x400;

#endif

        m_pos -= t >> 2;

        m_pos -= *ip++ << 2;

        *op++ = *m_pos++; *op++ = *m_pos++; *op++ = *m_pos++;

        lit = 0;

        goto match_done;

        /* handle matches */

        do {

            if (t < 16)                     /* a M1 match */

            {

                m_pos = op - 1;

                m_pos -= t >> 2;

                m_pos -= *ip++ << 2;

                if (litp == NULL)

                    goto copy_m1;

                /* assert that there was a match just before */

                assert(lit >= 1 && lit <= 3);

                assert(litp == ip - 2 - lit - 2);

                assert((lzo_uint)(*litp & 3) == lit);

                nl = ip[-2] & 3;

                /* test if a match follows */

                if (nl == 0 && lit == 1 && ip[0] >= 16)

                {

                    next_lit = nl;

                    /* adjust length of previous short run */

                    lit += 2;

                    *litp = LZO_BYTE((*litp & ~3) | lit);

                    /* copy over the 2 literals that replace the match */

                    copy2(ip-2,m_pos,pd(op,m_pos));

                    o_m1_a++;

                }

                /* test if a literal run follows */

                else if (nl == 0 && ip[0] < 16 && ip[0] != 0 &&

                         (lit + 2 + ip[0] < 16))

                {

                    t = *ip++;

                    /* remove short run */

                    *litp &= ~3;

                    /* copy over the 2 literals that replace the match */

                    copy2(ip-3+1,m_pos,pd(op,m_pos));

                    /* move literals 1 byte ahead */

                    litp += 2;

                    if (lit > 0)

                        lzo_memmove(litp+1,litp,lit);

                    /* insert new length of long literal run */

                    lit += 2 + t + 3; assert(lit <= 18);

                    *litp = LZO_BYTE(lit - 3);

                    o_m1_b++;

                    *op++ = *m_pos++; *op++ = *m_pos++;

                    goto copy_literal_run;

                }

copy_m1:

                *op++ = *m_pos++; *op++ = *m_pos++;

            }

            else

            {

match:

                if (t >= 64)                /* a M2 match */

                {

                    m_pos = op - 1;

#if defined(LZO1X)

                    m_pos -= (t >> 2) & 7;

                    m_pos -= *ip++ << 3;

                    t = (t >> 5) - 1;

#elif defined(LZO1Y)

                    m_pos -= (t >> 2) & 3;

                    m_pos -= *ip++ << 2;

                    t = (t >> 4) - 3;

#endif

                    if (litp == NULL)

                        goto copy_m;

                    nl = ip[-2] & 3;

                    /* test if in beetween two long literal runs */

                    if (t == 1 && lit > 3 && nl == 0 &&

                        ip[0] < 16 && ip[0] != 0 && (lit + 3 + ip[0] < 16))

                    {

                        assert(*litp == lit - 3);

                        t = *ip++;

                        /* copy over the 3 literals that replace the match */

                        copy3(ip-1-2,m_pos,pd(op,m_pos));

                        /* set new length of previous literal run */

                        lit += 3 + t + 3; assert(lit <= 18);

                        *litp = LZO_BYTE(lit - 3);

                        o_m2++;

                        *op++ = *m_pos++; *op++ = *m_pos++; *op++ = *m_pos++;

                        goto copy_literal_run;

                    }

                }

                else

                {

                    if (t >= 32)            /* a M3 match */

                    {

                        t &= 31;

                        if (t == 0)

                        {

                            t = 31;

                            while (*ip == 0)

                                t += 255, ip++;

                            t += *ip++;

                        }

                        m_pos = op - 1;

                        m_pos -= *ip++ >> 2;

                        m_pos -= *ip++ << 6;

                    }

                    else                    /* a M4 match */

                    {

                        m_pos = op;

                        m_pos -= (t & 8) << 11;

                        t &= 7;

                        if (t == 0)

                        {

                            t = 7;

                            while (*ip == 0)

                                t += 255, ip++;

                            t += *ip++;

                        }

                        m_pos -= *ip++ >> 2;

                        m_pos -= *ip++ << 6;

                        if (m_pos == op)

                            goto eof_found;

                        m_pos -= 0x4000;

                    }

                    if (litp == NULL)

                        goto copy_m;

                    nl = ip[-2] & 3;

                    /* test if in beetween two matches */

                    if (t == 1 && lit == 0 && nl == 0 && ip[0] >= 16)

                    {

                        assert(litp == ip - 3 - lit - 2);

                        assert((lzo_uint)(*litp & 3) == lit);

                        next_lit = nl;

                        /* make a previous short run */

                        lit += 3;

                        *litp = LZO_BYTE((*litp & ~3) | lit);

                        /* copy over the 3 literals that replace the match */

                        copy3(ip-3,m_pos,pd(op,m_pos));

                        o_m3_a++;

                    }

                    /* test if a literal run follows */

                    else if (t == 1 && lit <= 3 && nl == 0 &&

                             ip[0] < 16 && ip[0] != 0 && (lit + 3 + ip[0] < 16))

                    {

                        assert(litp == ip - 3 - lit - 2);

                        assert((lzo_uint)(*litp & 3) == lit);

                        t = *ip++;

                        /* remove short run */

                        *litp &= ~3;

                        /* copy over the 3 literals that replace the match */

                        copy3(ip-4+1,m_pos,pd(op,m_pos));

                        /* move literals 1 byte ahead */

                        litp += 2;

                        if (lit > 0)

                            lzo_memmove(litp+1,litp,lit);

                        /* insert new length of long literal run */

                        lit += 3 + t + 3; assert(lit <= 18);

                        *litp = LZO_BYTE(lit - 3);

                        o_m3_b++;

                        *op++ = *m_pos++; *op++ = *m_pos++; *op++ = *m_pos++;

                        goto copy_literal_run;

                    }

                }

copy_m:

                *op++ = *m_pos++; *op++ = *m_pos++;

                do *op++ = *m_pos++; while (--t > 0);

            }

match_done:

            if (next_lit == NO_LIT)

            {

                t = ip[-2] & 3;

                lit = t;

                litp = ip - 2;

            }

            else

                t = next_lit;

            assert(t <= 3);

            next_lit = NO_LIT;

            if (t == 0)

                break;

            /* copy literals */

match_next:

            do *op++ = *ip++; while (--t > 0);

            t = *ip++;

        } while (TEST_IP && TEST_OP);

    }

    /* no EOF code was found */

    *out_len = pd(op, out);

    return LZO_E_EOF_NOT_FOUND;

eof_found:

    assert(t == 1);

#if 0

    printf("optimize: %5lu %5lu   %5lu   %5lu %5lu\n",

           o_m1_a, o_m1_b, o_m2, o_m3_a, o_m3_b);

#endif

    LZO_UNUSED(o_m1_a); LZO_UNUSED(o_m1_b); LZO_UNUSED(o_m2);

    LZO_UNUSED(o_m3_a); LZO_UNUSED(o_m3_b);

    *out_len = pd(op, out);

    return (ip == ip_end ? LZO_E_OK :

           (ip < ip_end  ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));

}

/*

vi:ts=4:et

*/