lzo-2.03/src/lzo1b_r.ch

/* lzo1b_r.ch -- literal run handling for the the LZO1B/LZO1C 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/
 */


/***********************************************************************
// store a literal run (internal)
************************************************************************/

LZO_PUBLIC(lzo_bytep )
STORE_RUN ( lzo_bytep const oo, const lzo_bytep const ii, lzo_uint r_len)
{
    register lzo_bytep op;
    register const lzo_bytep ip;
    register lzo_uint t;

    LZO_STATS(lzo_stats->literals += r_len);

    op = oo;
    ip = ii;
    assert(r_len > 0);

    /* code a long R0 run */
    if (r_len >= 512)
    {
        unsigned r_bits = 6;        /* 256 << 6 == 16384 */
        lzo_uint tt = 32768u;

        while (r_len >= (t = tt))
        {
            r_len -= t;
            *op++ = 0; *op++ = (R0FAST - R0MIN) + 7;
            MEMCPY8_DS(op, ip, t);
            LZO_STATS(lzo_stats->r0long_runs++);
        }
        tt >>= 1;
        do {
            if (r_len >= (t = tt))
            {
                r_len -= t;
                *op++ = 0; *op++ = LZO_BYTE((R0FAST - R0MIN) + r_bits);
                MEMCPY8_DS(op, ip, t);
                LZO_STATS(lzo_stats->r0long_runs++);
            }
            tt >>= 1;
        } while (--r_bits > 0);
    }
    assert(r_len < 512);

    while (r_len >= (t = R0FAST))
    {
        r_len -= t;
        *op++ = 0; *op++ = (R0FAST - R0MIN);
        MEMCPY8_DS(op, ip, t);
        LZO_STATS(lzo_stats->r0fast_runs++);
    }

    t = r_len;
    if (t >= R0MIN)
    {
        /* code a short R0 run */
        *op++ = 0; *op++ = LZO_BYTE(t - R0MIN);
        MEMCPY_DS(op, ip, t);
        LZO_STATS(lzo_stats->r0short_runs++);
    }
    else if (t > 0)
    {
        /* code a short literal run */
        LZO_STATS(lzo_stats->lit_runs++);
        LZO_STATS(lzo_stats->lit_run[t]++);
        *op++ = LZO_BYTE(t);
        MEMCPY_DS(op, ip, t);
    }

    return op;
}


/*
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*/