/* lzo1a.c -- implementation of the LZO1A 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 "lzo_conf.h"

#include <lzo/lzo1a.h>

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

// The next two defines can be changed to customize LZO1A.

// The default version is LZO1A-5/1.

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

/* run bits (3 - 5) - the compressor and the decompressor

 * must use the same value. */

#if !defined(RBITS)

#  define RBITS     5

#endif

/* compression level (1 - 9) - this only affects the compressor.

 * 1 is fastest, 9 is best compression ratio

 */

#if !defined(CLEVEL)

#  define CLEVEL    1           /* fastest by default */

#endif

/* Collect statistics */

#if 0 && !defined(LZO_COLLECT_STATS)

#  define LZO_COLLECT_STATS 1

#endif

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

// You should not have to change anything below this line.

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

/* check configuration */

#if (RBITS < 3 || RBITS > 5)

#  error "invalid RBITS"

#endif

#if (CLEVEL < 1 || CLEVEL > 9)

#  error "invalid CLEVEL"

#endif

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

// internal configuration

// all of these affect compression only

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

/* choose the hashing strategy */

#ifndef LZO_HASH

#define LZO_HASH    LZO_HASH_LZO_INCREMENTAL_A

#endif

#define D_INDEX1(d,p)       d = DM(DMUL(0x21,DX2(p,5,5)) >> 5)

#define D_INDEX2(d,p)       d = d ^ D_MASK

#include "lzo1a_de.h"

#include "stats1a.h"

/* check other constants */

#if (LBITS < 5 || LBITS > 8)

#  error "invalid LBITS"

#endif

#if (LZO_COLLECT_STATS)

   static lzo1a_stats_t lzo_statistics;

   lzo1a_stats_t *lzo1a_stats = &lzo_statistics;

#  define lzo_stats lzo1a_stats

#endif

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

// get algorithm info, return memory required for compression

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

LZO_EXTERN(lzo_uint) lzo1a_info ( int *rbits, int *clevel );

LZO_PUBLIC(lzo_uint)

lzo1a_info ( int *rbits, int *clevel )

{

    if (rbits)

        *rbits = RBITS;

    if (clevel)

        *clevel = CLEVEL;

    return D_SIZE * lzo_sizeof(lzo_bytep);

}

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

// LZO1A decompress a block of data.

//

// Could be easily translated into assembly code.

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

LZO_PUBLIC(int)

lzo1a_decompress ( const lzo_bytep in , lzo_uint  in_len,

                         lzo_bytep out, lzo_uintp out_len,

                         lzo_voidp wrkmem )

{

    lzo_bytep op;

    const lzo_bytep ip;

    lzo_uint t;

    const lzo_bytep m_pos;

    const lzo_bytep const ip_end = in + in_len;

    LZO_UNUSED(wrkmem);

    op = out;

    ip = in;

    while (ip < ip_end)

    {

        t = *ip++;      /* get marker */

        LZO_STATS(lzo_stats->marker[t]++);

        if (t == 0)             /* a R0 literal run */

        {

            t = *ip++;

            if (t >= R0FAST - R0MIN)            /* a long R0 run */

            {

                t -= R0FAST - R0MIN;

                if (t == 0)

                    t = R0FAST;

                else

                {

#if 0

                    t = 256u << ((unsigned) t);

#else

                    /* help the optimizer */

                    lzo_uint tt = 256;

                    do tt <<= 1; while (--t > 0);

                    t = tt;

#endif

                }

                MEMCPY8_DS(op,ip,t);

                continue;

            }

            t += R0MIN;

            goto literal;

        }

        else if (t < R0MIN)     /* a short literal run */

        {

literal:

            MEMCPY_DS(op,ip,t);

        /* after a literal a match must follow */

            while (ip < ip_end)

            {

                t = *ip++;          /* get R1 marker */

                if (t >= R0MIN)

                    goto match;

            /* R1 match - a context sensitive 3 byte match + 1 byte literal */

                assert((t & OMASK) == t);

                m_pos = op - MIN_OFFSET;

                m_pos -= t | (((lzo_uint) *ip++) << OBITS);

                assert(m_pos >= out); assert(m_pos < op);

                *op++ = m_pos[0];

                *op++ = m_pos[1];

                *op++ = m_pos[2];

                *op++ = *ip++;

            }

        }

        else                    /* a match */

        {

match:

            /* get match offset */

            m_pos = op - MIN_OFFSET;

            m_pos -= (t & OMASK) | (((lzo_uint) *ip++) << OBITS);

            assert(m_pos >= out); assert(m_pos < op);

            /* get match len */

            if (t < ((MSIZE - 1) << OBITS))         /* a short match */

            {

                t >>= OBITS;

                *op++ = *m_pos++;

                *op++ = *m_pos++;

                MEMCPY_DS(op,m_pos,t);

            }

            else                                     /* a long match */

            {

#if (LBITS < 8)

                t = (MIN_MATCH_LONG - THRESHOLD) + ((lzo_uint)(*ip++) & LMASK);

#else

                t = (MIN_MATCH_LONG - THRESHOLD) + (lzo_uint)(*ip++);

#endif

                *op++ = *m_pos++;

                *op++ = *m_pos++;

                MEMCPY_DS(op,m_pos,t);

#if (LBITS < 8)

                /* a very short literal following a long match */

                t = ip[-1] >> LBITS;

                if (t) do

                    *op++ = *ip++;

                while (--t);

#endif

            }

        }

    }

    *out_len = pd(op, out);

    /* the next line is the only check in the decompressor */

    return (ip == ip_end ? LZO_E_OK :

           (ip < ip_end  ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));

}

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

// LZO1A compress a block of data.

//

// I apologize for the spaghetti code, but it really helps the optimizer.

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

#include "lzo1a_cr.ch"

static int

do_compress    ( const lzo_bytep in , lzo_uint  in_len,

                       lzo_bytep out, lzo_uintp out_len,

                       lzo_voidp wrkmem )

{

    const lzo_bytep ip;

#if defined(__LZO_HASH_INCREMENTAL)

    lzo_xint dv;

#endif

    const lzo_bytep m_pos;

    lzo_bytep op;

    const lzo_bytep const ip_end = in+in_len - DVAL_LEN - MIN_MATCH_LONG;

    const lzo_bytep const in_end = in+in_len - DVAL_LEN;

    const lzo_bytep ii;

    lzo_dict_p const dict = (lzo_dict_p) wrkmem;

    const lzo_bytep r1 = ip_end;    /* pointer for R1 match (none yet) */

#if (LBITS < 8)

    const lzo_bytep im = ip_end;    /* pointer to last match start */

#endif

#if !defined(NDEBUG)

    const lzo_bytep m_pos_sav;

#endif

    op = out;

    ip = in;

    ii = ip;            /* point to start of current literal run */

    /* init dictionary */

#if (LZO_DETERMINISTIC)

    BZERO8_PTR(wrkmem,sizeof(lzo_dict_t),D_SIZE);

#endif

    DVAL_FIRST(dv,ip); UPDATE_D(dict,0,dv,ip,in); ip++;

    DVAL_NEXT(dv,ip);

    do {

        LZO_DEFINE_UNINITIALIZED_VAR(lzo_uint, m_off, 0);

        lzo_uint dindex;

        DINDEX1(dindex,ip);

        GINDEX(m_pos,m_off,dict,dindex,in);

        if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,MAX_OFFSET))

            goto literal;

        if (m_pos[0] == ip[0] && m_pos[1] == ip[1] && m_pos[2] == ip[2])

            goto match;

        DINDEX2(dindex,ip);

        GINDEX(m_pos,m_off,dict,dindex,in);

        if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,MAX_OFFSET))

            goto literal;

        if (m_pos[0] == ip[0] && m_pos[1] == ip[1] && m_pos[2] == ip[2])

            goto match;

        goto literal;

literal:

        UPDATE_I(dict,0,dindex,ip,in);

        if (++ip >= ip_end)

            break;

        continue;

match:

        UPDATE_I(dict,0,dindex,ip,in);

#if !defined(NDEBUG) && (LZO_DICT_USE_PTR)

        assert(m_pos == NULL || m_pos >= in);

        m_pos_sav = m_pos;

#endif

        m_pos += 3;

        {

    /* we have found a match (of at least length 3) */

#if !defined(NDEBUG) && !(LZO_DICT_USE_PTR)

            assert((m_pos_sav = ip - m_off) == (m_pos - 3));

#endif

            assert(m_pos >= in);

            assert(ip < ip_end);

            /* 1) store the current literal run */

            if (pd(ip,ii) > 0)

            {

                lzo_uint t = pd(ip,ii);

                if (ip - r1 == MIN_MATCH + 1)

                {

                /* Code a context sensitive R1 match.

                 * This is tricky and somewhat difficult to explain:

                 * multiplex a literal run of length 1 into the previous

                 * short match of length MIN_MATCH.

                 * The key idea is:

                 *  - after a short run a match MUST follow

                 *  - therefore the value m = 000 in the mmmooooo marker is free

                 *  - use 000ooooo to indicate a MIN_MATCH match (this

                 *    is already coded) plus a 1 byte literal

                 */

                    assert(t == 1);

                    /* modify marker byte */

                    assert((op[-2] >> OBITS) == (MIN_MATCH - THRESHOLD));

                    op[-2] &= OMASK;

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

                    /* copy 1 literal */

                    *op++ = *ii;

                    LZO_STATS(lzo_stats->r1_matches++);

                    r1 = ip;                /* set new R1 pointer */

                }

                else if (t < R0MIN)

                {

                    /* inline the copying of a short run */

#if (LBITS < 8)

                    if (t < (1 << (8-LBITS)) && ii - im >= MIN_MATCH_LONG)

                    {

                    /* Code a very short literal run into the

                     * previous long match length byte.

                     */

                        LZO_STATS(lzo_stats->lit_runs_after_long_match++);

                        LZO_STATS(lzo_stats->lit_run_after_long_match[t]++);

                        assert(ii - im <= MAX_MATCH_LONG);

                        assert((op[-1] >> LBITS) == 0);

                        op[-1] = LZO_BYTE(op[-1] | (t << LBITS));

                        MEMCPY_DS(op, ii, t);

                    }

                    else

#endif

                    {

                        LZO_STATS(lzo_stats->lit_runs++);

                        LZO_STATS(lzo_stats->lit_run[t]++);

                        *op++ = LZO_BYTE(t);

                        MEMCPY_DS(op, ii, t);

                        r1 = ip;                /* set new R1 pointer */

                    }

                }

                else if (t < R0FAST)

                {

                    /* inline the copying of a short R0 run */

                    LZO_STATS(lzo_stats->r0short_runs++);

                    *op++ = 0; *op++ = LZO_BYTE(t - R0MIN);

                    MEMCPY_DS(op, ii, t);

                    r1 = ip;                /* set new R1 pointer */

                }

                else

                    op = store_run(op,ii,t);

            }

#if (LBITS < 8)

            im = ip;

#endif

            /* 2) compute match len */

            ii = ip;        /* point to start of current match */

            /* we already matched MIN_MATCH bytes,

             * m_pos also already advanced MIN_MATCH bytes */

            ip += MIN_MATCH;

            assert(m_pos < ip);

            /* try to match another MIN_MATCH_LONG - MIN_MATCH bytes

             * to see if we get a long match */

#define PS  *m_pos++ != *ip++

#if (MIN_MATCH_LONG - MIN_MATCH == 2)                   /* MBITS == 2 */

            if (PS || PS)

#elif (MIN_MATCH_LONG - MIN_MATCH == 6)                 /* MBITS == 3 */

            if (PS || PS || PS || PS || PS || PS)

#elif (MIN_MATCH_LONG - MIN_MATCH == 14)                /* MBITS == 4 */

            if (PS || PS || PS || PS || PS || PS || PS ||

                PS || PS || PS || PS || PS || PS || PS)

#elif (MIN_MATCH_LONG - MIN_MATCH == 30)                /* MBITS == 5 */

            if (PS || PS || PS || PS || PS || PS || PS || PS ||

                PS || PS || PS || PS || PS || PS || PS || PS ||

                PS || PS || PS || PS || PS || PS || PS || PS ||

                PS || PS || PS || PS || PS || PS)

#else

#  error "MBITS not yet implemented"

#endif

            {

            /* we've found a short match */

                lzo_uint m_len;

            /* 2a) compute match parameters */

                    assert(ip-m_pos == (int)m_off);

                --ip;   /* ran one too far, point back to non-match */

                m_len = pd(ip, ii);

                    assert(m_len >= MIN_MATCH_SHORT);

                    assert(m_len <= MAX_MATCH_SHORT);

                    assert(m_off >= MIN_OFFSET);

                    assert(m_off <= MAX_OFFSET);

                    assert(ii-m_off == m_pos_sav);

                    assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0);

                m_off -= MIN_OFFSET;

            /* 2b) code a short match */

                /* code short match len + low offset bits */

                *op++ = LZO_BYTE(((m_len - THRESHOLD) << OBITS) |

                                 (m_off & OMASK));

                /* code high offset bits */

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

#if (LZO_COLLECT_STATS)

                lzo_stats->short_matches++;

                lzo_stats->short_match[m_len]++;

                if (m_off < OSIZE)

                    lzo_stats->short_match_offset_osize[m_len]++;

                if (m_off < 256)

                    lzo_stats->short_match_offset_256[m_len]++;

                if (m_off < 1024)

                    lzo_stats->short_match_offset_1024[m_len]++;

#endif

            /* 2c) Insert phrases (beginning with ii+1) into the dictionary. */

#define SI      /* nothing */

#define DI      ++ii; DVAL_NEXT(dv,ii); UPDATE_D(dict,0,dv,ii,in);

#define XI      assert(ii < ip); ii = ip; DVAL_FIRST(dv,(ip));

#if (CLEVEL == 9) || (CLEVEL >= 7 && MBITS <= 4) || (CLEVEL >= 5 && MBITS <= 3)

            /* Insert the whole match (ii+1)..(ip-1) into dictionary.  */

                ++ii;

                do {

                    DVAL_NEXT(dv,ii);

                    UPDATE_D(dict,0,dv,ii,in);

                } while (++ii < ip);

                DVAL_NEXT(dv,ii);

                assert(ii == ip);

                DVAL_ASSERT(dv,ip);

#elif (CLEVEL >= 3)

                SI   DI DI   XI

#elif (CLEVEL >= 2)

                SI   DI      XI

#else

                             XI

#endif

            }

            else

            {

            /* we've found a long match - see how far we can still go */

                const lzo_bytep end;

                lzo_uint m_len;

                assert(ip <= in_end);

                assert(ii == ip - MIN_MATCH_LONG);

                if (pd(in_end,ip) <= (MAX_MATCH_LONG - MIN_MATCH_LONG))

                    end = in_end;

                else

                {

                    end = ip + (MAX_MATCH_LONG - MIN_MATCH_LONG);

                    assert(end < in_end);

                }

                while (ip < end && *m_pos == *ip)

                    { m_pos++; ip++; }

                assert(ip <= in_end);

            /* 2a) compute match parameters */

                m_len = pd(ip, ii);

                    assert(m_len >= MIN_MATCH_LONG);

                    assert(m_len <= MAX_MATCH_LONG);

                    assert(m_off >= MIN_OFFSET);

                    assert(m_off <= MAX_OFFSET);

                    assert(ii-m_off == m_pos_sav);

                    assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0);

                    assert(pd(ip,m_pos) == m_off);

                m_off -= MIN_OFFSET;

            /* 2b) code the long match */

                /* code long match flag + low offset bits */

                *op++ = LZO_BYTE(((MSIZE - 1) << OBITS) | (m_off & OMASK));

                /* code high offset bits */

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

                /* code match len */

                *op++ = LZO_BYTE(m_len - MIN_MATCH_LONG);

#if (LZO_COLLECT_STATS)

                lzo_stats->long_matches++;

                lzo_stats->long_match[m_len]++;

#endif

            /* 2c) Insert phrases (beginning with ii+1) into the dictionary. */

#if (CLEVEL == 9)

            /* Insert the whole match (ii+1)..(ip-1) into dictionary.  */

            /* This is not recommended because it is slow. */

                ++ii;

                do {

                    DVAL_NEXT(dv,ii);

                    UPDATE_D(dict,0,dv,ii,in);

                } while (++ii < ip);

                DVAL_NEXT(dv,ii);

                assert(ii == ip);

                DVAL_ASSERT(dv,ip);

#elif (CLEVEL >= 8)

                SI   DI DI DI DI DI DI DI DI   XI

#elif (CLEVEL >= 7)

                SI   DI DI DI DI DI DI DI      XI

#elif (CLEVEL >= 6)

                SI   DI DI DI DI DI DI         XI

#elif (CLEVEL >= 5)

                SI   DI DI DI DI               XI

#elif (CLEVEL >= 4)

                SI   DI DI DI                  XI

#elif (CLEVEL >= 3)

                SI   DI DI                     XI

#elif (CLEVEL >= 2)

                SI   DI                        XI

#else

                                               XI

#endif

            }

            /* ii now points to the start of the next literal run */

            assert(ii == ip);

        }

    } while (ip < ip_end);

    assert(ip <= in_end);

#if defined(LZO_RETURN_IF_NOT_COMPRESSIBLE)

    /* return -1 if op == out to indicate that we

     * couldn't compress and didn't copy anything.

     */

    if (op == out)

    {

        *out_len = 0;

        return LZO_E_NOT_COMPRESSIBLE;

    }

#endif

    /* store the final literal run */

    if (pd(in_end+DVAL_LEN,ii) > 0)

        op = store_run(op,ii,pd(in_end+DVAL_LEN,ii));

    *out_len = pd(op, out);

    return 0;               /* compression went ok */

}

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

// LZO1A compress public entry point.

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

LZO_PUBLIC(int)

lzo1a_compress ( const lzo_bytep in , lzo_uint  in_len,

                       lzo_bytep out, lzo_uintp out_len,

                       lzo_voidp wrkmem )

{

    int r = LZO_E_OK;

#if (LZO_COLLECT_STATS)

    lzo_memset(lzo_stats,0,sizeof(*lzo_stats));

    lzo_stats->rbits  = RBITS;

    lzo_stats->clevel = CLEVEL;

    lzo_stats->dbits  = DBITS;

    lzo_stats->lbits  = LBITS;

    lzo_stats->min_match_short = MIN_MATCH_SHORT;

    lzo_stats->max_match_short = MAX_MATCH_SHORT;

    lzo_stats->min_match_long  = MIN_MATCH_LONG;

    lzo_stats->max_match_long  = MAX_MATCH_LONG;

    lzo_stats->min_offset      = MIN_OFFSET;

    lzo_stats->max_offset      = MAX_OFFSET;

    lzo_stats->r0min  = R0MIN;

    lzo_stats->r0fast = R0FAST;

    lzo_stats->r0max  = R0MAX;

    lzo_stats->in_len = in_len;

#endif

    /* don't try to compress a block that's too short */

    if (in_len == 0)

        *out_len = 0;

    else if (in_len <= MIN_MATCH_LONG + DVAL_LEN + 1)

    {

#if defined(LZO_RETURN_IF_NOT_COMPRESSIBLE)

        r = LZO_E_NOT_COMPRESSIBLE;

#else

        *out_len = pd(store_run(out,in,in_len), out);

#endif

    }

    else

        r = do_compress(in,in_len,out,out_len,wrkmem);

#if (LZO_COLLECT_STATS)

    lzo_stats->short_matches -= lzo_stats->r1_matches;

    lzo_stats->short_match[MIN_MATCH] -= lzo_stats->r1_matches;

    lzo_stats->out_len = *out_len;

#endif

    return r;

}

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