!
!
! MKISM.BAS ... program to build and execute a command file which will
! allocate a new ISAM file.
!
! Utilizes the empty index block calculations outlined in the article:
!	"ISAM: Calculating the Number of Empty Index Blocks"
!				- AMSD Journal, November, 1985
!
! Author: 	Creed Erickson
!		Computer Systems Plus, Inc. 
!		1630 Manheim Pike
!		Lancaster, Pa.    17601
!		(717)-560-0140
!
! This program is released to the public domain on 12-June-1986.
! The author assumes no liability for use of this program for any purpose.
!
! edit history (latest first):
!
!	[001] 	New code. 12-Jun-86 / CAE
!

	program MKISM,1.0(1)

map1 STRINGS
	map2 ISAM'FILE'NAME,	S,6	! name of file to build
	map2 IS'PRIMARY,	S,1	! primary index? (Y/N)
	map2 DATA'FILE'DEVN,	S,7	! data file device and drive
	map2 SECONDARY'INDEX'NAME,S,6	! secondary index file spec
	map2 LOAD'FROM'FILE,	S,30	! sequential load file spec

map1 REALS
	map2 KEY'SIZE,		F,6	! user key size
	map2 KEY'POSITION,	F,6	! position of key within rec
	map2 RECORD'SIZE,	F,6	! size of data file record
	map2 NUMBER'OF'RECS,	F,6,100 ! number of records to allocate
	map2 ACTUAL'KEYSIZ,	F,6	! actual size of key on disk
	map2 DIRECTORY'ENTRY'SIZE,F,6	! size of ISAM directory entry
	map2 BLOCKING'FACTOR,	F,6	! # of ISAM directory entries per disk block
	map2 HALF'FACTOR,	F,6	! one-half of the above number
	map2 N,			F,6	! work variable
	map2 FIRST'LEVEL,	F,6	!--+
 	map2 SECOND'LEVEL,	F,6	!   \
	map2 THIRD'LEVEL,	F,6	!    \
	map2 FILE'SIZE,		F,6	!     >>>--- see referenced article
	map2 TOP'LEVEL,		F,6	!    /
	map2 MIDDLE'LEVEL,	F,6	!   /
	map2 BOTTOM'LEVEL,	F,6	!  /
	map2 SMALL'SIZE,	F,6	!-+
	map2 EMPTY'IDX'BLOCKS,	F,6	! # empty index blocks to allocate 


	print "Make ISAM file utility."

	input line "Name of file to be built ";ISAM'FILE'NAME

	input line "Size of key "; KEY'SIZE

	input line "Position of key ";KEY'POSITION

	input line "Size of record ";RECORD'SIZE

	input line "Number of records to allocate ";NUMBER'OF'RECS

	if (KEY'SIZE/2) = int(KEY'SIZE/2) then &
		     ACTUAL'KEYSIZ = KEY'SIZE &
		else ACTUAL'KEYSIZ = KEY'SIZE + 1

	DIRECTORY'ENTRY'SIZE = ACTUAL'KEYSIZ + 4
	BLOCKING'FACTOR = int(508/DIRECTORY'ENTRY'SIZE)

	HALF'FACTOR = int(BLOCKING'FACTOR/2)

	N =  int((NUMBER'OF'RECS-BLOCKING'FACTOR+1)/HALF'FACTOR)
	THIRD'LEVEL = (N+1) MAX 1
	
	N = int((THIRD'LEVEL-BLOCKING'FACTOR)/HALF'FACTOR)
	SECOND'LEVEL = (N+1) MAX 1

	N = int((SECOND'LEVEL-BLOCKING'FACTOR)/HALF'FACTOR)
	FIRST'LEVEL = (N+1) MAX 1

	FILE'SIZE = FIRST'LEVEL + SECOND'LEVEL + THIRD'LEVEL

	BOTTOM'LEVEL = int(NUMBER'OF'RECS/BLOCKING'FACTOR)
	if BOTTOM'LEVEL <> (NUMBER'OF'RECS/BLOCKING'FACTOR) then &
		BOTTOM'LEVEL = BOTTOM'LEVEL + 1

	MIDDLE'LEVEL = int(BOTTOM'LEVEL/BLOCKING'FACTOR)
	if MIDDLE'LEVEL <> (BOTTOM'LEVEL/BLOCKING'FACTOR) then &
		MIDDLE'LEVEL = MIDDLE'LEVEL + 1

	TOP'LEVEL = int(MIDDLE'LEVEL/BLOCKING'FACTOR)
	if TOP'LEVEL <> (MIDDLE'LEVEL/BLOCKING'FACTOR) then &
		TOP'LEVEL = TOP'LEVEL + 1

	SMALL'SIZE = TOP'LEVEL + MIDDLE'LEVEL + BOTTOM'LEVEL
	
	EMPTY'IDX'BLOCKS = FILE'SIZE - SMALL'SIZE 

	print str(EMPTY'IDX'BLOCKS);" empty index blocks will be allocated"

	input line "Primary directory? ";IS'PRIMARY
	IS'PRIMARY = ucs(IS'PRIMARY)

	input line "Data file device: ";DATA'FILE'DEVN

	if IS'PRIMARY = "N" then &
		input line "Secondary index: ";SECONDARY'INDEX'NAME

	INPUT LINE "Load from file: ";LOAD'FROM'FILE

	open #1, "MKISM.CMD", output
	print #1, ":S"
	print #1, "ERASE MKISM.CMD"
	print #1, "ISMBLD "+ISAM'FILE'NAME
	print #1, str(KEY'SIZE)
	print #1, str(KEY'POSITION)
	print #1, str(RECORD'SIZE)
	print #1, str(NUMBER'OF'RECS)
	print #1, str(EMPTY'IDX'BLOCKS)
	print #1, IS'PRIMARY
	print #1, DATA'FILE'DEVN
	if IS'PRIMARY = "N" then print #1, SECONDARY'INDEX'NAME
	print #1, LOAD'FROM'FILE
	print #1, ":R"
	close #1
	chain "MKISM.CMD"