This package implements a superset of the hsearch and dbm/ndbm libraries.

Contents:

Hashing Package:
	dynahash.c
	page.c
	buf.c
	big.c
	hfunc.c
	log2.c

	hash.h
	page.h
	db.h

Backward Compatibility Routines:
	ndbm.c
	ndbm.h
	hsearch.c
	search.h

Misc
	byte_order.c

Compatibility Files:
	endian.h
	posix.h
	mkstemp.c
	bcopy.c
	cdefs.h

DIFFS:
	These are diffs since the date of the file (i.e. a file labeled
	DIFFS.2.12 are the diffs since the 2.12 version on arpa).  The
	date of the DIFF file indicates when those diffs were installed.

DIFFS.2.25 changes
	Update man page
	Add copyrights 
	Make all bucket and overflow addresses unsigned
	add flag to hash_get for consistency with documentation
	make dbm_fetch set dsize to 0 when elements aren't found for
		backward compatibility
	Add ANSI prototypes for DB structure
	Change HASHINFO element ncached to cachesize for consistency
	Make bitmaps demand loaded rather than load ahead on open
	Fix RDONLY behaviour so meta data is not written out
Test Programs:
	All test programs which need key/data pairs expect them entered
	with key and data on separate lines

	tcreat3.c	
		Takes 
			bucketsize (bsize), 
			fill factor (ffactor), and
			initial number of elements (nelem).  
		Creates a hash table named hashtest containing the 
		keys/data pairs entered from standard in.
	thash4.c
		Takes
			bucketsize (bsize), 
			fill factor (ffactor), 
			initial number of elements (nelem)
			bytes of cache (ncached), and
			file from which to read data  (fname)
		Creates a table from the key/data pairs on standard in and
		then does a read of each key/data in fname
	tdel.c
		Takes
			bucketsize (bsize), and
			fill factor (ffactor).
			file from which to read data (fname)
		Reads each key/data pair from fname and deletes the
		key from the hash table hashtest
	tseq.c
		Reads the key/data pairs in the file hashtest and writes them
		to standard out.
	tread2.c
		Takes
			butes of cache (ncached).
		Reads key/data pairs from standard in and looks them up
		in the file hashtest.
	tverify.c
		Reads key/data pairs from standard in, looks them up
		in the file hashtest, and verifies that the data is
		correct.

NOTES:

The compatibility files should enable you to compile on some number of
machines.  
	endian.h	determine byte ordering (already included on some
			systems via sys/param.h)
	posix.h		Define posix signal handling
	mkstemp.c	On BSD systems, should already be in libc
	bcopy.c		Provided for systems without it.
	cdefs.h		Use for ANSI compatibility on systems that are
			not ANSI compliant.

Be sure to set BYTE_ORDER in endian.h appropriately for your machine.  
If you don't know what "endian" your machine is, compile byte_order.c 
and run it.  It should tell you.

Some known compile time fixes:

BSD4.3 		define "extern int errno" in hash.h
		include posix.h in hash.h


The file search.h is used only for using the hsearch compatible interface on
BSD systems.  On System V derived systems, search.h should appear in 
/usr/include.

The man page db.3 explains the interface to the hashing system.
The file hash.ps is a postscript copy of a paper explaining
the history, implementation, and performance of the hash package.

"bugs" or idiosyncracies

If you have a lot of overflows, it is possible to run out of overflow
pages.  Currently, this will cause a message to be printed on stderr.
Eventually, this will be indicated by a return error code.

If you are using the ndbm interface and exit without flushing or closing the
file, you may lose updates since the package buffers all writes.

There is a fundamental difference between this package and the old hsearch.
Hsearch requires the user to maintain the keys and data in the application's
allocated memory while hash takes care of all storage management.  The down
side is that the byte strings passed in the ENTRY structure must be null
terminated (both the keys and the data).


