/* lzo2a_9x.c -- implementation of the LZO2A-999 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 "config2a.h"

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

//

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

#define SWD_THRESHOLD       1           /* lower limit for match length */

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

#define LZO2A 1

#define LZO_COMPRESS_T  lzo2a_999_t

#define lzo_swd_t       lzo2a_999_swd_t

#include "lzo_mchw.ch"

#if (LZO_CC_BORLANDC && LZO_MM_FLAT)

#  if ((__BORLANDC__) >= 0x0450 && (__BORLANDC__) < 0x0460)

     /* avoid internal compiler error */

#    pragma option -Od

#  endif

#endif

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

//

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

#define putbyte(x)      *op++ = LZO_BYTE(x)

#define putbits(j,x) \

    if (k == 0) bitp = op++; \

    SETBITS(j,x); \

    if (k >= 8) { *bitp = LZO_BYTE(MASKBITS(8)); DUMPBITS(8); \

                    if (k > 0) bitp = op++; }

#define putbit(x)       putbits(1,x)

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

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

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

LZO_EXTERN(int)

lzo2a_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)

lzo2a_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;

    lzo_bytep bitp = 0;

    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;

    lzo_uint32_t b = 0;     /* bit buffer */

    unsigned k = 0;         /* bits in bit buffer */

    /* sanity check */

    LZO_COMPILE_TIME_ASSERT(LZO2A_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->m1 = c->m2 = c->m3 = c->m4 = 0;

    op = out;

    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)

    {

        lzo_uint lazy_match_min_gain = 0;

#if (SWD_N >= 8192)

        lzo_uint extra1 = 0;

#endif

        lzo_uint extra2 = 0;

        lzo_uint ahead = 0;

        m_len = c->m_len;

        m_off = c->m_off;

#if (SWD_N >= 8192)

        if (m_off >= 8192)

        {

            if (m_len < M3_MIN_LEN)

                m_len = 0;

            else

                lazy_match_min_gain = 1;

        }

        else

#endif

        if (m_len >= M1_MIN_LEN && m_len <= M1_MAX_LEN && m_off <= 256)

        {

            lazy_match_min_gain = 2;

#if (SWD_N >= 8192)

            extra1 = 3;

#endif

            extra2 = 2;

        }

        else if (m_len >= 10)

            lazy_match_min_gain = 1;

        else if (m_len >= 3)

        {

            lazy_match_min_gain = 1;

#if (SWD_N >= 8192)

            extra1 = 1;

#endif

        }

        else

            m_len = 0;

        /* try a lazy match */

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

        {

            unsigned char lit = LZO_BYTE(swd->b_char);

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

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

            assert(c->look > 0);

#if (SWD_N >= 8192)

            if (m_off < 8192 && c->m_off >= 8192)

                lazy_match_min_gain += extra1;

            else

#endif

            if (m_len >= M1_MIN_LEN && m_len <= M1_MAX_LEN && m_off <= 256)

            {

                if (!(c->m_len >= M1_MIN_LEN &&

                      c->m_len <= M1_MAX_LEN && c->m_off <= 256))

                    lazy_match_min_gain += extra2;

            }

            if (c->m_len >= M1_MIN_LEN &&

                c->m_len <= M1_MAX_LEN && c->m_off <= 256)

            {

                    lazy_match_min_gain -= 1;

            }

            if ((lzo_int) lazy_match_min_gain < 1)

                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);

                assert(m_len >= 3 || (m_len >= 2 && m_off <= 256));

#endif

                /* code literal */

                putbit(0);

                putbyte(lit);

                c->lit_bytes++;

                continue;

            }

            else

                ahead = 1;

            assert(m_len > 0);

        }

        if (m_len == 0)

        {

            /* a literal */

            putbit(0);

            putbyte(swd->b_char);

            c->lit_bytes++;

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

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

        }

        else

        {

            assert(m_len >= M1_MIN_LEN);

            assert(m_off > 0);

            assert(m_off <= SWD_N);

            /* 2 - code match */

            if (m_len >= M1_MIN_LEN && m_len <= M1_MAX_LEN && m_off <= 256)

            {

                putbit(1);

                putbit(0);

                putbits(2,m_len - M1_MIN_LEN);

                putbyte(m_off - 1);

                c->m1++;

            }

#if (SWD_N >= 8192)

            else if (m_off >= 8192)

            {

                unsigned len = m_len;

                assert(m_len >= M3_MIN_LEN);

                putbit(1);

                putbit(1);

                putbyte(m_off & 31);

                putbyte(m_off >> 5);

                putbit(1);

                len -= M3_MIN_LEN - 1;

                while (len > 255)

                {

                    len -= 255;

                    putbyte(0);

                }

                putbyte(len);

                c->m4++;

            }

#endif

            else

            {

                assert(m_len >= 3);

                putbit(1);

                putbit(1);

                if (m_len <= 9)

                {

                    putbyte(((m_len - 2) << 5) | (m_off & 31));

                    putbyte(m_off >> 5);

                    c->m2++;

                }

                else

                {

                    lzo_uint len = m_len;

                    putbyte(m_off & 31);

                    putbyte(m_off >> 5);

#if (SWD_N >= 8192)

                    putbit(0);

#endif

                    len -= 10 - 1;

                    while (len > 255)

                    {

                        len -= 255;

                        putbyte(0);

                    }

                    putbyte(len);

                    c->m3++;

                }

            }

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

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

        }

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

    }

#if defined(LZO_EOF_CODE)

    /* code EOF code */

    putbit(1);

    putbit(1);

    putbyte(1 << 5);

    putbyte(0);

#endif

    /* flush remaining bits */

    assert(k < CHAR_BIT);

    if (k > 0)

    {

        assert(b == MASKBITS(k));

        assert(op - bitp > 1);

        *bitp = LZO_BYTE(MASKBITS(k));

        DUMPBITS(k);

        assert(b == 0);

        assert(k == 0);

    }

    assert(c->textsize == in_len);

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

    *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) c->codesize,

        c->lit_bytes, c->m1, c->m2, c->m3, c->m4, c->lazy);

#endif

    return LZO_E_OK;

}

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

//

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

LZO_PUBLIC(int)

lzo2a_999_compress  ( const lzo_bytep in , lzo_uint  in_len,

                            lzo_bytep out, lzo_uintp out_len,

                            lzo_voidp wrkmem )

{

    return lzo2a_999_compress_callback(in,in_len,out,out_len,wrkmem,

                                       (lzo_callback_p) 0, 0);

}

/* vim:set ts=4 sw=4 et: */