Blob Blame History Raw
/* 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) 1996-2014 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
   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

// 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 */
static const char *progname = NULL;
#define WANT_XMALLOC 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)
#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_voidp 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) 1996-2014 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) xmalloc(IN_LEN);
    out = (lzo_bytep) xmalloc(OUT_LEN);
    wrkmem = (lzo_voidp) xmalloc(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;

 * 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);
        /* 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);
        /* this should NEVER happen */
        printf("internal error - decompression failed: %d\n", r);
        return 1;

    printf("Simple compression test passed.\n");
    return 0;

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