/* lzo1f_d.ch -- implementation of the LZO1F decompression 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 "lzo1_d.ch"

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

// decompress a block of data.

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

LZO_PUBLIC(int)

DO_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;

#if defined(HAVE_ANY_OP)

    lzo_bytep const op_end = out + *out_len;

#endif

    LZO_UNUSED(wrkmem);

    *out_len = 0;

    op = out;

    ip = in;

    while (TEST_IP_AND_TEST_OP)

    {

        t = *ip++;

        if (t > 31)

            goto match;

        /* a literal run */

        if (t == 0)

        {

            NEED_IP(1);

            while (*ip == 0)

            {

                t += 255;

                ip++;

                TEST_IV(t);

                NEED_IP(1);

            }

            t += 31 + *ip++;

        }

        /* copy literals */

        assert(t > 0); NEED_OP(t); NEED_IP(t+1);

#if (LZO_OPT_UNALIGNED32)

        if (t >= 4)

        {

            do {

                UA_COPY4(op, ip);

                op += 4; ip += 4; t -= 4;

            } while (t >= 4);

            if (t > 0) do *op++ = *ip++; while (--t > 0);

        }

        else

#endif

        do *op++ = *ip++; while (--t > 0);

        t = *ip++;

        while (TEST_IP_AND_TEST_OP)

        {

            /* handle matches */

            if (t < 32)

            {

                m_pos = op - 1 - 0x800;

                m_pos -= (t >> 2) & 7;

                m_pos -= *ip++ << 3;

                TEST_LB(m_pos); NEED_OP(3);

                *op++ = *m_pos++; *op++ = *m_pos++; *op++ = *m_pos++;

            }

            else

            {

match:

                if (t < M3_MARKER)

                {

                    m_pos = op - 1;

                    m_pos -= (t >> 2) & 7;

                    m_pos -= *ip++ << 3;

                    t >>= 5;

                    TEST_LB(m_pos); assert(t > 0); NEED_OP(t+3-1);

                    goto copy_match;

                }

                else

                {

                    t &= 31;

                    if (t == 0)

                    {

                        NEED_IP(1);

                        while (*ip == 0)

                        {

                            t += 255;

                            ip++;

                            TEST_OV(t);

                            NEED_IP(1);

                        }

                        t += 31 + *ip++;

                    }

                    NEED_IP(2);

                    m_pos = op;

#if (LZO_OPT_UNALIGNED16) && (LZO_ABI_LITTLE_ENDIAN)

                    m_pos -= UA_GET_LE16(ip) >> 2;

                    ip += 2;

#else

                    m_pos -= *ip++ >> 2;

                    m_pos -= *ip++ << 6;

#endif

                    if (m_pos == op)

                        goto eof_found;

                }

                /* copy match */

                TEST_LB(m_pos); assert(t > 0); NEED_OP(t+3-1);

#if (LZO_OPT_UNALIGNED32)

                if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4)

                {

                    UA_COPY4(op, m_pos);

                    op += 4; m_pos += 4; t -= 4 - (3 - 1);

                    do {

                        UA_COPY4(op, m_pos);

                        op += 4; m_pos += 4; t -= 4;

                    } while (t >= 4);

                    if (t > 0) do *op++ = *m_pos++; while (--t > 0);

                }

                else

#endif

                {

copy_match:

                *op++ = *m_pos++; *op++ = *m_pos++;

                do *op++ = *m_pos++; while (--t > 0);

                }

            }

            t = ip[-2] & 3;

            if (t == 0)

                break;

            /* copy literals */

            assert(t > 0); NEED_OP(t); NEED_IP(t+1);

            do *op++ = *ip++; while (--t > 0);

            t = *ip++;

        }

    }

#if defined(HAVE_TEST_IP) || defined(HAVE_TEST_OP)

    /* no EOF code was found */

    *out_len = pd(op, out);

    return LZO_E_EOF_NOT_FOUND;

#endif

eof_found:

    assert(t == 1);

    *out_len = pd(op, out);

    return (ip == ip_end ? LZO_E_OK :

           (ip < ip_end  ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));

#if defined(HAVE_NEED_IP)

input_overrun:

    *out_len = pd(op, out);

    return LZO_E_INPUT_OVERRUN;

#endif

#if defined(HAVE_NEED_OP)

output_overrun:

    *out_len = pd(op, out);

    return LZO_E_OUTPUT_OVERRUN;

#endif

#if defined(LZO_TEST_OVERRUN_LOOKBEHIND)

lookbehind_overrun:

    *out_len = pd(op, out);

    return LZO_E_LOOKBEHIND_OVERRUN;

#endif

}

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