/* lzo1b_9x.c -- implementation of the LZO1B-999 compression algorithm

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

   Copyright (C) 1996-2014 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 "config1b.h"

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

//

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

#define SWD_N          0xffffL          /* size of ring buffer */

#define SWD_THRESHOLD       2           /* lower limit for match length */

#define SWD_F            2048           /* upper limit for match length */

#define LZO1B 1

#define LZO_COMPRESS_T  lzo1b_999_t

#define lzo_swd_t       lzo1b_999_swd_t

#include "lzo_mchw.ch"

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

//

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

static lzo_bytep

code_match ( LZO_COMPRESS_T *c, lzo_bytep op, lzo_uint m_len, lzo_uint m_off )

{

    if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET)

    {

        assert(m_len >= M2_MIN_LEN);

        assert(m_off >= M2_MIN_OFFSET);

        m_off -= M2_MIN_OFFSET;

        /* code match len + low offset bits */

        *op++ = LZO_BYTE(((m_len - (M2_MIN_LEN - 2)) << M2O_BITS) |

                          (m_off & M2O_MASK));

        /* code high offset bits */

        *op++ = LZO_BYTE(m_off >> M2O_BITS);

        c->m2_m++;

    }

    else

    {

        assert(m_len >= M3_MIN_LEN);

        assert(m_off <= M3_MAX_OFFSET);

        m_off -= M3_MIN_OFFSET - M3_EOF_OFFSET;

        /* code match len */

        if (m_len <= M3_MAX_LEN)

            *op++ = LZO_BYTE(M3_MARKER | (m_len - (M3_MIN_LEN - 1)));

        else

        {

            assert(m_len >= M4_MIN_LEN);

            /* code M4 match len flag */

            *op++ = M4_MARKER;

            /* code match len */

            m_len -= M4_MIN_LEN - 1;

            while (m_len > 255)

            {

                m_len -= 255;

                *op++ = 0;

            }

            assert(m_len > 0);

            *op++ = LZO_BYTE(m_len);

        }

        /* code low offset bits */

        *op++ = LZO_BYTE(m_off & M3O_MASK);

        /* code high offset bits */

        *op++ = LZO_BYTE(m_off >> M3O_BITS);

        c->r1_m_len = 0;

        c->m3_m++;

    }

    return op;

}

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

// this is a public function, but there is no prototype in a header file

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

LZO_EXTERN(int)

lzo1b_999_compress_callback ( const lzo_bytep in , lzo_uint  in_len,

                                    lzo_bytep out, lzo_uintp out_len,

                                    lzo_voidp wrkmem,

                                    lzo_callback_p cb,

                                    lzo_uint max_chain );

LZO_PUBLIC(int)

lzo1b_999_compress_callback ( const lzo_bytep in , lzo_uint  in_len,

                                    lzo_bytep out, lzo_uintp out_len,

                                    lzo_voidp wrkmem,

                                    lzo_callback_p cb,

                                    lzo_uint max_chain )

{

    lzo_bytep op;

    const lzo_bytep ii;

    lzo_uint lit;

    lzo_uint m_len, m_off;

    LZO_COMPRESS_T cc;

    LZO_COMPRESS_T * const c = &cc;

    lzo_swd_p const swd = (lzo_swd_p) wrkmem;

    int r;

    /* sanity check */

    LZO_COMPILE_TIME_ASSERT(LZO1B_999_MEM_COMPRESS >= SIZEOF_LZO_SWD_T)

    c->init = 0;

    c->ip = c->in = in;

    c->in_end = in + in_len;

    c->cb = cb;

    c->r1_r = c->m3_r = c->m2_m = c->m3_m = 0;

    op = out;

    ii = c->ip;             /* point to start of literal run */

    lit = 0;

    c->r1_m_len = 0;

    r = init_match(c,swd,NULL,0,0);

    if (r != 0)

        return r;

    if (max_chain > 0)

        swd->max_chain = max_chain;

    r = find_match(c,swd,0,0);

    if (r != 0)

        return r;

    while (c->look > 0)

    {

        int lazy_match_min_gain = -1;

        lzo_uint ahead = 0;

        m_len = c->m_len;

        m_off = c->m_off;

#if 0

        printf("%5ld: %5d len:%3d off:%5d\n", (c->ip-c->look)-in, c->look,

                m_len, m_off);

#endif

        assert(c->ip - c->look >= in);

        if (lit == 0)

            ii = c->ip - c->look;

        assert(ii + lit == c->ip - c->look);

        assert(swd->b_char == *(c->ip - c->look));

        if ((m_len < M2_MIN_LEN) ||

            (m_len < M3_MIN_LEN && m_off > M2_MAX_OFFSET))

        {

            m_len = 0;

        }

        else

        {

            assert(c->ip - c->look - m_off >= in);

            assert(c->ip - c->look - m_off + m_len < c->ip);

            assert(lzo_memcmp(c->ip - c->look, c->ip - c->look - m_off,

                              m_len) == 0);

            if (lit > 0)

            {

                /* we have a current literal run: do not try a lazy match,

                   if the literal could be coded into a r1 match */

                if (lit == 1 && c->r1_m_len == M2_MIN_LEN)

                    lazy_match_min_gain = -1;

                else

                    lazy_match_min_gain = 1;

#if (M2_MIN_LEN == 2)

                if (m_len == 2)

                {

                    /* don't code a match of len 2 if we have to

                       code a literal run. Code a literal instead. */

                    m_len = 0;

                }

#endif

#if (M2_MIN_LEN == M3_MIN_LEN)

                if (m_len == M2_MIN_LEN && m_off > M2_MAX_OFFSET)

                {

                    /* don't code a M3 match of len 3 if we have to

                       code a literal run. Code a literal instead. */

                    m_len = 0;

                }

#endif

            }

            else

            {

                /* no current literal run: only try a lazy match,

                   if the literal could be coded into a r1 match */

                if (c->r1_m_len == M2_MIN_LEN)

                    lazy_match_min_gain = 0;

                else

                    lazy_match_min_gain = -1;

            }

        }

        /* try a lazy match */

        if (m_len == 0)

            lazy_match_min_gain = -1;

        if (lazy_match_min_gain >= 0 && c->look > m_len)

        {

            assert(m_len > 0);

            r = find_match(c,swd,1,0);

            assert(r == 0); LZO_UNUSED(r);

            assert(c->look > 0);

            if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET &&

                c->m_off > M2_MAX_OFFSET)

                lazy_match_min_gain += 1;

            if (c->m_len >= m_len + lazy_match_min_gain)

            {

                c->lazy++;

#if !defined(NDEBUG)

                m_len = c->m_len;

                m_off = c->m_off;

                assert(lzo_memcmp(c->ip - c->look, c->ip - c->look - m_off,

                                  m_len) == 0);

#endif

                lit++;

                assert(ii + lit == c->ip - c->look);

                continue;

            }

            else

            {

                ahead = 1;

                assert(ii + lit + 1 == c->ip - c->look);

            }

            assert(m_len > 0);

        }

        assert(ii + lit + ahead == c->ip - c->look);

        if (m_len == 0)

        {

            /* a literal */

            lit++;

            r = find_match(c,swd,1,0);

            assert(r == 0); LZO_UNUSED(r);

        }

        else

        {

            /* 1 - store run */

            if (lit > 0)

            {

                /* code current literal run */

                if (lit == 1 && c->r1_m_len == M2_MIN_LEN)

                {

                    /* Code a context sensitive R1 match. */

                    assert((op[-2] >> M2O_BITS) == (M2_MARKER >> M2O_BITS));

                    op[-2] &= M2O_MASK;

                    assert((op[-2] >> M2O_BITS) == 0);

                    /* copy 1 literal */

                    *op++ = *ii++;

                    assert(ii + ahead == c->ip - c->look);

                    c->r1_r++;

                }

                else

                {

                    op = STORE_RUN(op,ii,lit);

                }

                if (lit < R0FAST)

                    c->r1_m_len = m_len;

                else

                    c->r1_m_len = 0;

                lit = 0;

            }

            else

                c->r1_m_len = 0;

            /* 2 - code match */

            op = code_match(c,op,m_len,m_off);

            r = find_match(c,swd,m_len,1+ahead);

            assert(r == 0); LZO_UNUSED(r);

        }

        c->codesize = pd(op, out);

    }

    /* store final run */

    if (lit > 0)

        op = STORE_RUN(op,ii,lit);

#if defined(LZO_EOF_CODE)

    *op++ = M3_MARKER | 1;

    *op++ = 0;

    *op++ = 0;

#endif

    c->codesize = pd(op, out);

    assert(c->textsize == in_len);

    *out_len = pd(op, out);

    if (c->cb && c->cb->nprogress)

        (*c->cb->nprogress)(c->cb, c->textsize, c->codesize, 0);

#if 0

    printf("%ld %ld -> %ld: %ld %ld %ld %ld %ld\n",

        (long) c->textsize, (long)in_len, (long) c->codesize,

        c->r1_r, c->m3_r, c->m2_m, c->m3_m, c->lazy);

#endif

    return LZO_E_OK;

}

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

//

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

LZO_PUBLIC(int)

lzo1b_999_compress  ( const lzo_bytep in , lzo_uint  in_len,

                            lzo_bytep out, lzo_uintp out_len,

                            lzo_voidp wrkmem )

{

    return lzo1b_999_compress_callback(in,in_len,out,out_len,wrkmem,

                                       (lzo_callback_p) 0, 0);

}

/*

vi:ts=4:et

*/