patch-2.1.66 linux/drivers/char/ftape/compressor/zftape-compress.h

• Lines: 84
• Date: Tue Nov 25 14:45:27 1997
• Orig file: v2.1.65/linux/drivers/char/ftape/compressor/zftape-compress.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.65/linux/drivers/char/ftape/compressor/zftape-compress.h linux/drivers/char/ftape/compressor/zftape-compress.h
@@ -0,0 +1,83 @@
+#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 */