lzo-2.03/src/lzo1b_d.ch

/* lzo1b_d.ch -- implementation of the LZO1B decompression 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 "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 )
{
    register lzo_bytep op;
    register const lzo_bytep ip;
    register lzo_uint t;
    register 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);

    op = out;
    ip = in;

    while (TEST_IP && TEST_OP)
    {
        t = *ip++;      /* get marker */

        if (t < R0MIN)      /* a literal run */
        {
            if (t == 0)             /* a R0 literal run */
            {
                NEED_IP(1);
                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
                    }

                    NEED_IP(t); NEED_OP(t);
#if 1 && defined(LZO_UNALIGNED_OK_4)
                    do {
                        * (lzo_uint32p) (op+0) = * (const lzo_uint32p) (ip+0);
                        * (lzo_uint32p) (op+4) = * (const lzo_uint32p) (ip+4);
                        op += 8; ip += 8;
                        t -= 8;
                    } while (t > 0);
#else
                    MEMCPY8_DS(op,ip,t);
#endif
                    continue;
                }
                t += R0MIN;                         /* a short R0 run */
            }

            NEED_IP(t); NEED_OP(t);
            /* copy literal run */
#if 1 && defined(LZO_UNALIGNED_OK_4)
            if (t >= 4)
            {
                do {
                    * (lzo_uint32p) op = * (const lzo_uint32p) ip;
                    op += 4; ip += 4; t -= 4;
                } while (t >= 4);
                if (t > 0) do *op++ = *ip++; while (--t > 0);
            }
            else
#endif
            {
#if (M3O_BITS < 7)
literal1:
#endif
                do *op++ = *ip++; while (--t > 0);
            }

#if (M3O_BITS == 7)
literal2:
#endif

            /* after a literal a match must follow */
            while (TEST_IP && TEST_OP)
            {
                t = *ip++;          /* get R1 marker */
                if (t >= R0MIN)
                    goto match;

                NEED_IP(2); NEED_OP(M2_MIN_LEN + 1);

            /* R1 match - a M2_MIN_LEN match + 1 byte literal */
                assert((t & M2O_MASK) == t);
                m_pos = op - M2_MIN_OFFSET;
                m_pos -= t | (((lzo_uint) *ip++) << M2O_BITS);
                assert(m_pos >= out); assert(m_pos < op);
                TEST_LB(m_pos);
                COPY_M2;
                *op++ = *ip++;
            }

#if defined(HAVE_TEST_IP) || defined(HAVE_TEST_OP)
            break;
#endif
        }

match:

        if (t >= M2_MARKER)             /* a M2 match */
        {
            /* get match offset */
            NEED_IP(1);
            m_pos = op - M2_MIN_OFFSET;
            m_pos -= (t & M2O_MASK) | (((lzo_uint) *ip++) << M2O_BITS);
            assert(m_pos >= out); assert(m_pos < op);
            TEST_LB(m_pos);

            /* get match len */
            t = (t >> M2O_BITS) - 1;
            NEED_OP(t + M2_MIN_LEN - 1);
            COPY_M2X;
            MEMCPY_DS(op,m_pos,t);
        }
        else                            /* a M3 or M4 match */
        {
            /* get match len */
            t &= M3L_MASK;
            if (t == 0)         /* a M4 match */
            {
                NEED_IP(1);
                while (*ip == 0)
                {
                    t += 255;
                    ip++;
                    NEED_IP(1);
                }
                t += (M4_MIN_LEN - M3_MIN_LEN) + *ip++;
            }

            /* get match offset */
            NEED_IP(2);
            m_pos = op - (M3_MIN_OFFSET - M3_EOF_OFFSET);
            m_pos -= *ip++ & M3O_MASK;
            m_pos -= (lzo_uint)(*ip++) << M3O_BITS;
#if defined(LZO_EOF_CODE)
            if (m_pos == op)
                goto eof_found;
#endif

            /* copy match */
            assert(m_pos >= out); assert(m_pos < op);
            TEST_LB(m_pos); NEED_OP(t + M3_MIN_LEN - 1);
#if defined(LZO_UNALIGNED_OK_4)
            if (t >= 2 * 4 - (M3_MIN_LEN - 1) && (op - m_pos) >= 4)
            {
                * (lzo_uint32p) op = * (const lzo_uint32p) m_pos;
                op += 4; m_pos += 4; t -= 4 - (M3_MIN_LEN - 1);
                do {
                    * (lzo_uint32p) op = * (const lzo_uint32p) 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_M3X;
            MEMCPY_DS(op,m_pos,t);
            }


#if (M3O_BITS < 7)
            t = ip[-2] >> M3O_BITS;
            if (t)
            {
                NEED_IP(t); NEED_OP(t);
                goto literal1;
            }
#elif (M3O_BITS == 7)
            /* optimized version */
            if (ip[-2] & (1 << M3O_BITS))
            {
                NEED_IP(1); NEED_OP(1);
                *op++ = *ip++;
                goto literal2;
            }
#endif
        }
    }


#if defined(LZO_EOF_CODE)
#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);
#endif
    *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
}


/*
vi:ts=4:et
*/