/* REXX EXEC ********************************************** */
/* TRACE ALL */
/************************************************************/
/*REXX EXEC: CHECKSUM */
/*WRITTEN BY: JIM LEONE  DATE: 8/22/95 */
/*PURPOSE: TO CALCULATE THE CHECKSUM VALUE FOR ZAPS */
/*USAGE:	EDIT MACRO COMMAND IN EDIT MODE, */
/*	COMMAND:  CHECKSUM BEG END         */
/*	BEG = FIRST REP/VER STATEMENT */
/*	END = LAST REP/VER STATEMENT */
/*	FOLLOW  THE LAST REP/VER STATEMENT WITH A CHECKSUM STATEMENT AND THE MACRO WILL PUT THE CALCULATION ON THAT STATEMENT */
/*	*/
/*SPECIAL NOTE: HEX CHARACTERS MUST NOT BE SEPARATED BY COMMAS!! */
/*SPECIAL NOTE: YOU MUST REMOVE THE COMMAS FOR THE MACRO TO WORK! */
/************************************************************/
NUMERIC DIGITS 15
ADDRESS "ISREDIT" "MACRO (BEGL,ENDL)"
LOOPCTRL = ENDL - BEGL + 1
ALLVALUES = ‘’
 DO LOOPCTRL
	"ISREDIT (DATAL) = LINE" BEGL
	PARSE VAR DATAL OPER BASE HEXES .
	ALLVALUES = ALLVALUES || BASE || HEXES
 /* SAY "ALLVALUES = "ALLVALUES  */
	BEGL = BEGL + 1
 END
DONE =’NO’
HEXTOT = 0
DO UNTIL DONE = ‘YES’
	HEXLENGTH = LENGTH(ALLVALUES)
  IF HEXLENGTH < 16
	THEN
	DO
	DONE = ‘YES’
	CALL LASTONE
	HEXTOTAL = "‘CHECKSUM " || HEXTOT || "‘ .HERE .HERE"
	"ISREDIT RESET LABEL"
	"ISREDIT LABEL "ENDL + 1" = .HERE"
	ADDRESS "ISREDIT "
	"CHANGE ‘CHECKSUM’ " HEXTOTAL
	EXIT
	END
  ELSE
	DO  /* DO SUB1 */
	FIRST8 = SUBSTR(ALLVALUES,1,8)
	NEXT8 = SUBSTR(ALLVALUES,9,8)
	DEC1 = X2D(FIRST8)
	DEC2 = X2D(NEXT8)
	DECNUM = DEC1 + DEC2
	HEXSUB = D2X(DECNUM)
	IF LENGTH(HEXSUB) > 8
	THEN HEXSUB = SUBSTR(HEXSUB,2,8)
	DECTOT = X2D(HEXTOT) + X2D(HEXSUB)
	HEXTOT = D2X(DECTOT)
	IF LENGTH(HEXTOT) > 8
	THEN HEXTOT = SUBSTR(HEXTOT,2,8)
	ALLVALUES = SUBSTR(ALLVALUES,17)
	END /* DO SUB1 */
END  /* MAIN DO */
	HEXTOTAL = "‘CHECKSUM " || HEXTOT || "‘ .HERE .HERE"
	ADDRESS "ISREDIT "
	"ISREDIT RESET LABEL"
	"ISREDIT LABEL "ENDL + 1" = .HERE"
	"CHANGE ‘CHECKSUM’ " HEXTOTAL
EXIT
LASTONE:
  IF HEXLENGTH = 4
	THEN
	CALL LAST4
  IF HEXLENGTH = 8
	THEN
	CALL LAST8
  IF HEXLENGTH = 12
	THEN
	CALL LAST12
RETURN ‘’
LAST4:
	DO
	FIRST8 = ALLVALUES
	FIRST8 = FIRST8 || ‘0000’
	DEC1 = X2D(FIRST8)
	DECT1 = X2D(HEXTOT)
	DECNUM = DEC1 + DECT1
	HEXTOT = D2X(DECNUM)
	IF LENGTH(HEXTOT) > 8
	THEN HEXTOT = SUBSTR(HEXTOT,2,8)
	END
RETURN ‘’
LAST8:
	DO
	FIRST8 = ALLVALUES
	DEC1 = X2D(FIRST8)
	DECT1 = X2D(HEXTOT)
	DECNUM = DEC1 + DECT1
	HEXTOT = D2X(DECNUM)
	IF LENGTH(HEXTOT) > 8
	THEN HEXTOT = SUBSTR(HEXTOT,2,8)
	END
RETURN ‘’
LAST12:
	DO
	FIRST8 = SUBSTR(ALLVALUES,1,8)
	NEXT8 = SUBSTR(ALLVALUES,9,4)
	NEXT8 = NEXT8 || ‘0000’
	DEC1 = X2D(FIRST8)
	DEC2 = X2D(NEXT8)
	DECNUM = DEC1 + DEC2
	HEXSUB = D2X(DECNUM)
	IF LENGTH(HEXSUB) > 8
	THEN HEXSUB = SUBSTR(HEXSUB,2,8)
	DECT1 = X2D(HEXTOT)
	DECT2 = X2D(HEXSUB)
	DECTOT = DECT1 + DECT2
	HEXTOT = D2X(DECTOT)
	IF LENGTH(HEXTOT) > 8
	THEN HEXTOT = SUBSTR(HEXTOT,2,8)
	END
RETURN ‘’
 EXIT