1 /*
2  * Decompression convenience functions
3  *
4  * Copyright 2007 David Gibson, IBM Corporation.
5  *
6  * This file is licensed under the terms of the GNU General Public
7  * License version 2.  This program is licensed "as is" without any
8  * warranty of any kind, whether express or implied.
9  */
10 #ifndef _PPC_BOOT_GUNZIP_UTIL_H_
11 #define _PPC_BOOT_GUNZIP_UTIL_H_
12 
13 #include "zlib.h"
14 
15 /*
16  * These functions are designed to make life easy for decompressing
17  * kernel images, initrd images or any other gzip compressed image,
18  * particularly if its useful to decompress part of the image (e.g. to
19  * examine headers) before decompressing the remainder.
20  *
21  * To use:
22  *     - declare a gunzip_state structure
23  *     - use gunzip_start() to initialize the state, associating it
24  *       with a stream of compressed data
25  *     - use gunzip_partial(), gunzip_exactly() and gunzip_discard()
26  *       in any combination to extract pieces of data from the stream
27  *     - Finally use gunzip_finish() to extract the tail of the
28  *       compressed stream and wind up zlib
29  */
30 
31 /* scratch space for gunzip; 46912 is from zlib_inflate_workspacesize() */
32 #define GUNZIP_SCRATCH_SIZE	46912
33 
34 struct gunzip_state {
35 	z_stream s;
36 	char scratch[46912];
37 };
38 
39 void gunzip_start(struct gunzip_state *state, void *src, int srclen);
40 int gunzip_partial(struct gunzip_state *state, void *dst, int dstlen);
41 void gunzip_exactly(struct gunzip_state *state, void *dst, int len);
42 void gunzip_discard(struct gunzip_state *state, int len);
43 int gunzip_finish(struct gunzip_state *state, void *dst, int len);
44 
45 #endif /* _PPC_BOOT_GUNZIP_UTIL_H_ */
46