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+Puff -- A Simple Inflate
+3 Mar 2003
+Mark Adler
+madler@alumni.caltech.edu
+
+What this is --
+
+puff.c provides the routine puff() to decompress the deflate data format.  It
+does so more slowly than zlib, but the code is about one-fifth the size of the
+inflate code in zlib, and written to be very easy to read.
+
+Why I wrote this --
+
+puff.c was written to document the deflate format unambiguously, by virtue of
+being working C code.  It is meant to supplement RFC 1951, which formally
+describes the deflate format.  I have received many questions on details of the
+deflate format, and I hope that reading this code will answer those questions.
+puff.c is heavily commented with details of the deflate format, especially
+those little nooks and cranies of the format that might not be obvious from a
+specification.
+
+puff.c may also be useful in applications where code size or memory usage is a
+very limited resource, and speed is not as important.
+
+How to use it --
+
+Well, most likely you should just be reading puff.c and using zlib for actual
+applications, but if you must ...
+
+Include puff.h in your code, which provides this prototype:
+
+int puff(unsigned char *dest,           /* pointer to destination pointer */
+         unsigned long *destlen,        /* amount of output space */
+         unsigned char *source,         /* pointer to source data pointer */
+         unsigned long *sourcelen);     /* amount of input available */
+
+Then you can call puff() to decompress a deflate stream that is in memory in
+its entirety at source, to a sufficiently sized block of memory for the
+decompressed data at dest.  puff() is the only external symbol in puff.c  The
+only C library functions that puff.c needs are setjmp() and longjmp(), which
+are used to simplify error checking in the code to improve readabilty.  puff.c
+does no memory allocation, and uses less than 2K bytes off of the stack.
+
+If destlen is not enough space for the uncompressed data, then inflate will
+return an error without writing more than destlen bytes.  Note that this means
+that in order to decompress the deflate data successfully, you need to know
+the size of the uncompressed data ahead of time.
+
+If needed, puff() can determine the size of the uncompressed data with no
+output space.  This is done by passing dest equal to (unsigned char *)0.  Then
+the initial value of *destlen is ignored and *destlen is set to the length of
+the uncompressed data.  So if the size of the uncompressed data is not known,
+then two passes of puff() can be used--first to determine the size, and second
+to do the actual inflation after allocating the appropriate memory.  Not
+pretty, but it works.  (This is one of the reasons you should be using zlib.)
+
+The deflate format is self-terminating.  If the deflate stream does not end
+in *sourcelen bytes, puff() will return an error without reading at or past
+endsource.
+
+On return, *sourcelen is updated to the amount of input data consumed, and
+*destlen is updated to the size of the uncompressed data.  See the comments
+in puff.c for the possible return codes for puff().