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#ifndef _ZFTAPE_COMPRESS_H
#define _ZFTAPE_COMPRESS_H
/*
* Copyright (c) 1994-1997 Claus-Justus Heine
This program 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, or (at
your option) any later version.
This program 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 this program; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
USA.
*
* $Source: /homes/cvs/ftape-stacked/ftape/compressor/zftape-compress.h,v $
* $Revision: 1.1 $
* $Date: 1997/10/05 19:12:32 $
*
* This file contains macros and definitions for zftape's
* builtin compression code.
*
*/
#include "../zftape/zftape-buffers.h"
#include "../zftape/zftape-vtbl.h"
#include "../compressor/lzrw3.h"
/* CMPR_WRK_MEM_SIZE gives the size of the compression wrk_mem */
/* I got these out of lzrw3.c */
#define U(X) ((__u32) X)
#define SIZE_P_BYTE (U(sizeof(__u8 *)))
#define ALIGNMENT_FUDGE (U(16))
#define CMPR_WRK_MEM_SIZE (U(4096)*(SIZE_P_BYTE) + ALIGNMENT_FUDGE)
/* the maximum number of bytes the size of the "compressed" data can
* exceed the uncompressed data. As it is quite useless to compress
* data twice it is sometimes the case that it is more efficient to
* copy a block of data but to feed it to the "compression"
* algorithm. In this case there are some flag bytes or the like
* proceding the "compressed" data. THAT MUST NOT BE THE CASE for the
* algorithm we use for this driver. Instead, the high bit 15 of
* compressed_size:
*
* compressed_size = ftape_compress()
*
* must be set in such a case.
*
* Nevertheless, it might also be as for lzrw3 that there is an
* "intermediate" overrun that exceeds the amount of the compressed
* data that is actually produced. During the algorithm we need in the
* worst case MAX_CMP_GROUP bytes more than the input-size.
*/
#define MAX_CMP_GROUP (2+16*2) /* from lzrw3.c */
#define CMPR_OVERRUN MAX_CMP_GROUP /* during compression */
/****************************************************/
#define CMPR_BUFFER_SIZE (MAX_BLOCK_SIZE + CMPR_OVERRUN)
/* the compression map stores the byte offset compressed blocks within
* the current volume for catridges with format code 2,3 and 5
* (and old versions of zftape) and the offset measured in kilobytes for
* format code 4 and 6. This gives us a possible max. size of a
* compressed volume of 1024*4GIG which should be enough.
*/
typedef __u32 CmprMap;
/* globals
*/
/* exported functions
*/
#endif /* _ZFTAPE_COMPRESS_H */
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