path: root/src/lzo2a_9x.c

/* lzo2a_9x.c -- implementation of the LZO2A-999 compression algorithm

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

   Copyright (C) 1996-2015 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: */