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


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

#define THRESHOLD       1           /* lower limit for match length */
#define F            2048           /* upper limit for match length */


#define LZO2A
#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 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)
    {
        int lazy_match_min_gain = 0;
        int extra1 = 0;
        int extra2 = 0;
        lzo_uint ahead = 0;

        LZO_UNUSED(extra1);

        m_len = c->m_len;
        m_off = c->m_off;

#if (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;
            extra1 = 3;
            extra2 = 2;
        }
        else if (m_len >= 10)
            lazy_match_min_gain = 1;
        else if (m_len >= 3)
        {
            lazy_match_min_gain = 1;
            extra1 = 1;
        }
        else
            m_len = 0;


        /* try a lazy match */
        if (lazy_match_min_gain > 0 && c->look > m_len)
        {
            int lit = swd->b_char;

            r = find_match(c,swd,1,0);
            assert(r == 0);
            assert(c->look > 0);

#if (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 (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);
        }
        else
        {
            assert(m_len >= M1_MIN_LEN);
            assert(m_off > 0);
            assert(m_off <= 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 (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 (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);
        }

        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);
}


/*
vi:ts=4:et
*/