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Diffstat (limited to 'examples/simple.c')
| -rw-r--r-- | examples/simple.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/examples/simple.c b/examples/simple.c new file mode 100644 index 0000000..15611c9 --- /dev/null +++ b/examples/simple.c @@ -0,0 +1,168 @@ +/* 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 +*/ + |