arch/powerpc/boot/gunzip_util.h

   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_ */