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kernel/linux-rt-4.4.41/arch/powerpc/boot/gunzip_util.h 1.57 KB
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  /*
   * Decompression convenience functions
   *
   * Copyright 2007 David Gibson, IBM Corporation.
   *
   * This file is licensed under the terms of the GNU General Public
   * License version 2.  This program is licensed "as is" without any
   * warranty of any kind, whether express or implied.
   */
  #ifndef _PPC_BOOT_GUNZIP_UTIL_H_
  #define _PPC_BOOT_GUNZIP_UTIL_H_
  
  #include "zlib.h"
  
  /*
   * These functions are designed to make life easy for decompressing
   * kernel images, initrd images or any other gzip compressed image,
   * particularly if its useful to decompress part of the image (e.g. to
   * examine headers) before decompressing the remainder.
   *
   * To use:
   *     - declare a gunzip_state structure
   *     - use gunzip_start() to initialize the state, associating it
   *       with a stream of compressed data
   *     - use gunzip_partial(), gunzip_exactly() and gunzip_discard()
   *       in any combination to extract pieces of data from the stream
   *     - Finally use gunzip_finish() to extract the tail of the
   *       compressed stream and wind up zlib
   */
  
  /* scratch space for gunzip; 46912 is from zlib_inflate_workspacesize() */
  #define GUNZIP_SCRATCH_SIZE	46912
  
  struct gunzip_state {
  	z_stream s;
  	char scratch[46912];
  };
  
  void gunzip_start(struct gunzip_state *state, void *src, int srclen);
  int gunzip_partial(struct gunzip_state *state, void *dst, int dstlen);
  void gunzip_exactly(struct gunzip_state *state, void *dst, int len);
  void gunzip_discard(struct gunzip_state *state, int len);
  int gunzip_finish(struct gunzip_state *state, void *dst, int len);
  
  #endif /* _PPC_BOOT_GUNZIP_UTIL_H_ */