/* overlap.c -- example program: overlapping (de)compression   This file is part of the LZO real-time data compression library.   Copyright (C) 1996-2002 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.,   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.   Markus F.X.J. Oberhumer   <markus@oberhumer.com> *//*************************************************************************// This program shows how to do overlapping compression and// in-place decompression.//// Please study LZO.FAQ and simple.c first.**************************************************************************/#include <lzo1x.h>#include "lutil.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 / 64 + 16 + 3'. See step 5a) below. * * For overlapping compression '0xbfff + in_len / 64 + 16 + 3' bytes * will be needed. See step 4a) below. */static lzo_uint opt_overhead = 0;	/* assume worst case */#if 0 && defined(__GNUC__) && defined(__i386__)/* used for test purposes only */LZO_EXTERN_CDECL(int)lzo1x_decompress_asm_fast ( const lzo_byte *src, lzo_uint  src_len,                                  lzo_byte *dst, lzo_uintp dst_len,                                  lzo_voidp wrkmem /* NOT USED */ )                           __asm__("_lzo1x_decompress_asm_fast");#endif/*************************************************************************//**************************************************************************/static const char *progname = NULL;static unsigned long total_files = 0;static unsigned long total_in = 0;static lzo_byte *xmalloc(lzo_uint len){	lzo_byte *p;	p = (lzo_bytep) lzo_malloc(len > 0 ? len : 1);	if (p == NULL)	{		printf("%s: out of memory\n", progname);		exit(1);	}	return p;}/*************************************************************************//**************************************************************************/int do_file ( const char *in_name ){	int r;	FILE *f = NULL;	long l;	lzo_byte *wrkmem = NULL;	lzo_byte *in = NULL;	lzo_uint in_len;				/* uncompressed length */	lzo_byte *out = NULL;	lzo_uint out_len;				/* compressed length */	lzo_byte *overlap = NULL;	lzo_uint overhead;	lzo_uint offset;	lzo_uint new_len = 0;/* * Step 1: open the input file */ 	f = fopen(in_name,"rb");	if (f == NULL)	{		printf("%s: %s: cannot open file\n", progname, in_name);		goto next_file;	}	fseek(f,0,SEEK_END);	l = ftell(f);	fseek(f,0,SEEK_SET);	if (l <= 0)	{		printf("%s: %s: empty file -- skipping\n", progname, in_name);		goto next_file;	}	in_len = (lzo_uint) l;/* * Step 2: allocate compression buffers and read the file */	in = xmalloc(in_len);	out = xmalloc(in_len + in_len / 64 + 16 + 3);	wrkmem = xmalloc(LZO1X_1_MEM_COMPRESS);	in_len = lzo_fread(f,in,in_len);	fclose(f); f = NULL;	printf("%s: %s: read %ld bytes\n", progname, in_name, (long) in_len);	total_files++;	total_in += 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 / 64 + 16 + 3)	{		/* this should NEVER happen */		printf("internal error - compression failed: %d\n", r);		exit(1);	}	printf("%-26s %8lu -> %8lu\n", "LZO1X-1:", (long) in_len, (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 / 64 + 16 + 3;	overlap = 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("overlapping 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 l = in_len;		lzo_byte *tmp = xmalloc(l);		r = lzo1x_decompress_safe(overlap,new_len,tmp,&l,NULL); 		if (r != LZO_E_OK || l != in_len || lzo_memcmp(in,tmp,l) != 0)		{			/* this should NEVER happen */			printf("overlapping compression data error\n");			exit(1);		}		lzo_free(tmp);	}	printf("overlapping compression:   %8lu -> %8lu    overhead: %7ld\n",			(long) in_len, (long) new_len, (long) overhead);	lzo_free(overlap); overlap = NULL;/***** Step 5: overlapping decompression *****//* * Step 5a: allocate the `overlap' buffer for in-place decompression */ 	if (opt_overhead == 0 || out_len >= in_len)		overhead = in_len / 64 + 16 + 3;	else 		overhead = opt_overhead;	overlap = 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;#if 1	r = lzo1x_decompress(overlap+offset,out_len,overlap,&new_len,NULL);#else	r = lzo1x_decompress_asm_fast(overlap+offset,out_len,overlap,&new_len,NULL);#endif	if (r != LZO_E_OK)	{		/* this may happen if overhead is too small */		printf("overlapping 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("overlapping decompression data error - increase `opt_overhead'\n");		exit(1);	}	printf("overlapping decompression: %8lu -> %8lu    overhead: %7ld\n",			(long) out_len, (long) new_len, (long) overhead);	lzo_free(overlap); overlap = NULL;next_file:	lzo_free(overlap);	lzo_free(wrkmem);	lzo_free(out);	lzo_free(in);	if (f) fclose(f);	return 0;}/*************************************************************************//**************************************************************************/int main(int argc, char *argv[]){	int r;	int i = 1;#if defined(__EMX__)	_response(&argc,&argv);	_wildcard(&argc,&argv);#endif	printf("\nLZO real-time data compression library (v%s, %s).\n",	        lzo_version_string(), lzo_version_date());	printf("Copyright (C) 1996-2002 Markus Franz Xaver Johannes Oberhumer\n\n");	progname = argv[0];	if (i < argc && argv[i][0] == '-')		opt_overhead = atoi(&argv[i++][1]);#if 1	if (opt_overhead != 0 && opt_overhead < 8)	{		printf("%s: invalid overhead value %ld\n", progname, (long)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("lzo_init() failed !!!\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;}/*vi:ts=4*/