[POWERPC] Add documentation for the zImage's gunzip convenience functions

[linux-2.6-omap-h63xx.git] / arch / powerpc / boot / gunzip_util.h

diff --git a/arch/powerpc/boot/gunzip_util.h b/arch/powerpc/boot/gunzip_util.h
index 950f62fe0a6df82e4ce512e7bf54330546932d2c..b3dfa6e87b3a07cb43545c3d77a073d588ae551f 100644 (file)
--- a/arch/powerpc/boot/gunzip_util.h
+++ b/arch/powerpc/boot/gunzip_util.h
@@ -12,6 +12,22 @@
 
 #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
 
@@ -27,4 +43,3 @@ 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_ */
-