lzo-2.03/examples/simple.c

/* simple.c -- the annotated simple example program for the LZO library

   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/
 */


/*************************************************************************
// This program shows the basic usage of the LZO library.
// We will compress a block of data and decompress again.
//
// See also LZO.FAQ
**************************************************************************/

/* We will be using the LZO1X-1 algorithm, so we have
 * to include <lzo1x.h>
 */

#include "lzo/lzoconf.h"
#include "lzo/lzo1x.h"

/* portability layer */
#define WANT_LZO_MALLOC 1
#include "examples/portab.h"


/* We want to compress the data block at `in' with length `IN_LEN' to
 * the block at `out'. Because the input block may be incompressible,
 * we must provide a little more output space in case that compression
 * is not possible.
 */

#ifndef IN_LEN
#define IN_LEN      (128*1024L)
#endif
#define OUT_LEN     (IN_LEN + IN_LEN / 16 + 64 + 3)


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

int __lzo_cdecl_main main(int argc, char *argv[])
{
    int r;
    lzo_bytep in;
    lzo_bytep out;
    lzo_bytep wrkmem;
    lzo_uint in_len;
    lzo_uint out_len;
    lzo_uint new_len;

    if (argc < 0 && argv == NULL)   /* avoid warning about unused args */
        return 0;

    printf("\nLZO real-time data compression library (v%s, %s).\n",
           lzo_version_string(), lzo_version_date());
    printf("Copyright (C) 1996-2008 Markus Franz Xaver Johannes Oberhumer\nAll Rights Reserved.\n\n");

/*
 * Step 1: initialize the LZO library
 */
    if (lzo_init() != LZO_E_OK)
    {
        printf("internal error - lzo_init() failed !!!\n");
        printf("(this usually indicates a compiler bug - try recompiling\nwithout optimizations, and enable `-DLZO_DEBUG' for diagnostics)\n");
        return 4;
    }

/*
 * Step 2: allocate blocks and the work-memory
 */
    in = (lzo_bytep) lzo_malloc(IN_LEN);
    out = (lzo_bytep) lzo_malloc(OUT_LEN);
    wrkmem = (lzo_bytep) lzo_malloc(LZO1X_1_MEM_COMPRESS);
    if (in == NULL || out == NULL || wrkmem == NULL)
    {
        printf("out of memory\n");
        return 3;
    }

/*
 * Step 3: prepare the input block that will get compressed.
 *         We just fill it with zeros in this example program,
 *         but you would use your real-world data here.
 */
    in_len = IN_LEN;
    lzo_memset(in,0,in_len);

/*
 * Step 4: compress from `in' to `out' with LZO1X-1
 */
    r = lzo1x_1_compress(in,in_len,out,&out_len,wrkmem);
    if (r == LZO_E_OK)
        printf("compressed %lu bytes into %lu bytes\n",
            (unsigned long) in_len, (unsigned long) out_len);
    else
    {
        /* this should NEVER happen */
        printf("internal error - compression failed: %d\n", r);
        return 2;
    }
    /* check for an incompressible block */
    if (out_len >= in_len)
    {
        printf("This block contains incompressible data.\n");
        return 0;
    }

/*
 * Step 5: decompress again, now going from `out' to `in'
 */
    new_len = in_len;
    r = lzo1x_decompress(out,out_len,in,&new_len,NULL);
    if (r == LZO_E_OK && new_len == in_len)
        printf("decompressed %lu bytes back into %lu bytes\n",
            (unsigned long) out_len, (unsigned long) in_len);
    else
    {
        /* this should NEVER happen */
        printf("internal error - decompression failed: %d\n", r);
        return 1;
    }

    lzo_free(wrkmem);
    lzo_free(out);
    lzo_free(in);
    printf("Simple compression test passed.\n");
    return 0;
}

/*
vi:ts=4:et
*/