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-/* overlap.c -- example program: overlapping (de)compression
-
- 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
- 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 how to do overlapping compression and
-// in-place decompression.
-//
-// Please study LZO.FAQ and simple.c first.
-**************************************************************************/
-
-#include "lzo/lzoconf.h"
-#include "lzo/lzo1x.h"
-
-/* portability layer */
-static const char *progname = NULL;
-#define WANT_LZO_MALLOC 1
-#define WANT_LZO_FREAD 1
-#define WANT_LZO_WILDARGV 1
-#define WANT_XMALLOC 1
-#include "examples/portab.h"
-
-
-/* Overhead (in bytes) for the in-place decompression buffer.
- * Most files need only 16 !
- * (try 'overlap -16 file' or even 'overlap -8 file')
- *
- * Worst case (for files that are compressible by only a few bytes)
- * is 'in_len / 16 + 64 + 3'. See step 5a) below.
- *
- * For overlapping compression '0xbfff + in_len / 16 + 64 + 3' bytes
- * will be needed. See step 4a) below.
- */
-
-static long opt_overhead = 0; /* assume worst case */
-
-static unsigned long total_files = 0;
-static unsigned long total_in = 0;
-
-
-/*************************************************************************
-//
-**************************************************************************/
-
-static int do_file(const char *in_name)
-{
- int r;
- FILE *fp = NULL;
- long l;
-
- lzo_voidp wrkmem = NULL;
-
- lzo_bytep in = NULL;
- lzo_uint in_len; /* uncompressed length */
-
- lzo_bytep out = NULL;
- lzo_uint out_len; /* compressed length */
-
- lzo_bytep overlap = NULL;
- lzo_uint overhead;
- lzo_uint offset;
-
- lzo_uint new_len = 0;
-
-/*
- * Step 1: open the input file
- */
- fp = fopen(in_name, "rb");
- if (fp == NULL)
- {
- printf("%s: %s: cannot open file\n", progname, in_name);
- goto next_file;
- }
- fseek(fp, 0, SEEK_END);
- l = ftell(fp);
- fseek(fp, 0, SEEK_SET);
- if (l <= 0)
- {
- printf("%s: %s: empty file -- skipping\n", progname, in_name);
- goto next_file;
- }
- in_len = (lzo_uint) l;
- if ((long) in_len != l || l > 256L * 1024L * 1024L)
- {
- printf("%s: %s: file is too big -- skipping\n", progname, in_name);
- goto next_file;
- }
-
-/*
- * Step 2: allocate compression buffers and read the file
- */
- in = (lzo_bytep) xmalloc(in_len);
- out = (lzo_bytep) xmalloc(in_len + in_len / 16 + 64 + 3);
- wrkmem = (lzo_voidp) xmalloc(LZO1X_1_MEM_COMPRESS);
- in_len = (lzo_uint) lzo_fread(fp, in, in_len);
- fclose(fp); fp = NULL;
- printf("%s: %s: read %lu bytes\n", progname, in_name, (unsigned long) in_len);
-
- total_files++;
- total_in += (unsigned long) in_len;
-
-/*
- * Step 3: compress from 'in' to 'out' with LZO1X-1
- */
- r = lzo1x_1_compress(in, in_len, out, &out_len, wrkmem);
- if (r != LZO_E_OK || out_len > in_len + in_len / 16 + 64 + 3)
- {
- /* this should NEVER happen */
- printf("internal error - compression failed: %d\n", r);
- exit(1);
- }
- printf("%-25s %8lu -> %8lu\n", "LZO1X-1:", (unsigned long) in_len, (unsigned long) out_len);
-
-
-/***** Step 4: overlapping compression *****/
-
-/*
- * Step 4a: allocate the 'overlap' buffer for overlapping compression
- */
- overhead = in_len > 0xbfff ? 0xbfff : in_len;
- overhead += in_len / 16 + 64 + 3;
- overlap = (lzo_bytep) xmalloc(in_len + overhead);
-
-/*
- * Step 4b: prepare data in 'overlap' buffer.
- * copy uncompressed data at the top of the overlap buffer
- */
- /*** offset = in_len + overhead - in_len; ***/
- offset = overhead;
- lzo_memcpy(overlap + offset, in, in_len);
-
-/*
- * Step 4c: do an in-place compression within the 'overlap' buffer
- */
- r = lzo1x_1_compress(overlap + offset, in_len, overlap, &new_len, wrkmem);
- if (r != LZO_E_OK)
- {
- /* this should NEVER happen */
- printf("in-place compression failed: %d\n", r);
- exit(1);
- }
-
-/*
- * Step 4d: verify overlapping compression
- */
- if (new_len != out_len || lzo_memcmp(out, overlap, out_len) != 0)
- {
- /* As compression is non-deterministic there can be a difference
- * in the representation of the compressed data (but this usually
- * happens very seldom). So we have to verify the overlapping
- * compression by doing a temporary decompression.
- */
- lzo_uint ll = in_len;
- lzo_bytep tmp = (lzo_bytep) xmalloc(ll);
- r = lzo1x_decompress_safe(overlap, new_len, tmp, &ll, NULL);
- if (r != LZO_E_OK || ll != in_len || lzo_memcmp(in, tmp, ll) != 0)
- {
- /* this should NEVER happen */
- printf("in-place compression data error\n");
- exit(1);
- }
- lzo_free(tmp);
- }
-
- printf(" in-place compression: %8lu -> %8lu overhead: %7lu\n",
- (unsigned long) in_len, (unsigned long) new_len, (unsigned long) overhead);
- lzo_free(overlap); overlap = NULL;
-
-
-/***** Step 5: in-place decompression *****/
-
-/*
- * Step 5a: allocate the 'overlap' buffer for in-place decompression
- */
- if (opt_overhead == 0 || out_len >= in_len)
- overhead = in_len / 16 + 64 + 3;
- else
- overhead = (lzo_uint) opt_overhead;
- overlap = (lzo_bytep) xmalloc(in_len + overhead);
-
-/*
- * Step 5b: prepare data in 'overlap' buffer.
- * copy compressed data at the top of the overlap buffer
- */
- offset = in_len + overhead - out_len;
- lzo_memcpy(overlap + offset, out, out_len);
-
-/*
- * Step 5c: do an in-place decompression within the 'overlap' buffer
- */
- new_len = in_len;
- r = lzo1x_decompress_safe(overlap + offset, out_len, overlap, &new_len, NULL);
- if (r != LZO_E_OK)
- {
- /* this may happen if overhead is too small */
- printf("in-place decompression failed: %d - increase 'opt_overhead'\n", r);
- exit(1);
- }
-
-/*
- * Step 5d: verify decompression
- */
- if (new_len != in_len || lzo_memcmp(in, overlap, in_len) != 0)
- {
- /* this may happen if overhead is too small */
- printf("in-place decompression data error - increase 'opt_overhead'\n");
- exit(1);
- }
- printf(" in-place decompression: %8lu -> %8lu overhead: %7lu\n",
- (unsigned long) out_len, (unsigned long) new_len, (unsigned long) overhead);
- lzo_free(overlap); overlap = NULL;
-
-
-next_file:
- lzo_free(overlap);
- lzo_free(wrkmem);
- lzo_free(out);
- lzo_free(in);
- if (fp) fclose(fp);
-
- return 0;
-}
-
-
-/*************************************************************************
-//
-**************************************************************************/
-
-int __lzo_cdecl_main main(int argc, char *argv[])
-{
- int r;
- int i = 1;
-
- lzo_wildargv(&argc, &argv);
-
- 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");
-
- progname = argv[0];
- if (i < argc && argv[i][0] == '-')
- opt_overhead = atol(&argv[i++][1]);
-#if 1
- if (opt_overhead != 0 && opt_overhead < 4)
- {
- printf("%s: invalid overhead value %ld\n", progname, opt_overhead);
- exit(1);
- }
-#endif
- if (i >= argc)
- {
- printf("usage: %s [-overhead_in_bytes] file..\n", progname);
- exit(1);
- }
-
-/*
- * 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");
- exit(1);
- }
-
-/*
- * Step 2: process files
- */
- for (r = 0; r == 0 && i < argc; i++)
- r = do_file(argv[i]);
-
- printf("\nDone. Successfully processed %lu bytes in %lu files.\n",
- total_in, total_files);
- return r;
-}
-
-
-/* vim:set ts=4 sw=4 et: */
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